JP4238798B2 - Line head, method for manufacturing line head, and image forming apparatus - Google Patents

Description

  The present invention relates to a line head used as exposure means in an image forming apparatus, a method for manufacturing the same, and an image forming apparatus including the line head.

  A line printer (image forming apparatus) is known as an electrophotographic printer. In this line printer, devices such as a charger, a line-shaped printer head (line head), a developing device, and a transfer device are arranged close to each other on the peripheral surface of a photosensitive drum serving as an exposed portion. That is, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum charged by the charger by selective light emission operation of a light emitting element provided in the line head, and this latent image is formed. It is developed with toner supplied from a developing device, and the toner image is transferred onto a sheet by a transfer device.

  By the way, a light emitting diode or the like is generally used as the light emitting element of the line head as described above. However, this has a problem that it is extremely difficult to arrange thousands of light emitting points with high accuracy. Therefore, in recent years, an image forming apparatus including a light emitting element array using an organic electroluminescent element (organic EL element) capable of accurately forming a light emitting point as a light emitting element as an exposure unit has been proposed (for example, Patent Documents). 1).

  Moreover, in the electrophotographic line printer as described above, the radiation from the line head is usually used to convert the SELFOC (registered trademark) lens array (trade name of Nippon Sheet Glass; hereinafter, SELFOC (registered trademark) lens to SL, A system in which an image is formed on a photosensitive drum by passing through a SELFOC (registered trademark) lens array (referred to as an SL array) and exposed is employed. The SL array enables a wide range of images to be formed by arranging a large number of cylindrical SL elements that erect an equal magnification.

By the way, the image made by the SL array is formed by overlapping the images made by each SL element (erecting equal-magnification image formation), and the SL element has a light quantity distribution that halves football. is doing. Therefore, in the SL array, periodic light amount unevenness occurs with the arrangement pitch of each SL element.
However, when there is such periodic unevenness of light quantity, when the line head and the SL array are combined, the uniformity of light intensity in the main scanning direction is deteriorated due to the uneven light quantity of the SL array. The exposure accuracy is lowered, and the quality of the obtained print is impaired.

Against this background, as a technique for removing periodic light amount unevenness due to the imaging principle of the SL array, a technique for changing the thickness of the light emitting layer of the end face light emitting element (see, for example, Patent Document 2) and diffusion A technique for inserting a plate (see, for example, Patent Document 3) has been proposed. In addition, as a method of correcting the light amount period unevenness by the drive control of the light emitting element, a method of measuring the light amount unevenness of the line head in advance, storing the correction data in the memory, and correcting the drive data of the light emitting element with the correction data (for example, , See Patent Document 4).
JP 11-198433 A JP-A-5-330135 JP-A-8-197776 JP-A-9-314897

  However, the technique of changing the thickness of the light emitting layer of the edge light emitting device has problems such as variations in the life and characteristics of each light emitting device. Further, the technique of inserting a diffusion plate has a problem that the resolution of exposure is lowered. Furthermore, in the method of performing correction by driving control of the light emitting element, there is a problem that cost is required for forming a new circuit. As described above, a technology for eliminating the periodic light amount unevenness of the SL array has not been established, and therefore the provision thereof is desired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for eliminating the periodic light amount unevenness of the lens array and to provide an image forming apparatus provided with this line head. It is in.

In order to achieve the above object, a line head of the present invention is a line head in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion through a plurality of lens elements, and the light emitting element and the light emitting element A first microlens and a second microlens that condense light from the light emitting element and make the light incident on the lens element between the lens elements, and are disposed opposite to the periphery of the lens element The radius of curvature of the first microlens formed is smaller than the radius of curvature of the second microlens disposed opposite to the center of the lens element.
In order to achieve the above object, a line head of the present invention is a line head in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion via a plurality of lens elements, On the lens element side, a microlens for condensing light from the light emitting element and making it incident on the lens element is formed, and the curvature of the microlens arranged opposite to the periphery of the lens element is It is characterized by being formed smaller than the curvature of the microlens arranged opposite to the center.
According to this configuration, light emitted from the microlens having a small curvature is narrowed to the vicinity of the optical axis, so that more light can be incident on the peripheral portion of the lens element. Thereby, the light quantity distribution from the center part to the peripheral part of the lens element becomes flat, and the periodic light quantity unevenness of the lens array can be eliminated.

Further, the line head includes a plurality of light emitting elements arranged so as to irradiate light to an exposed portion through the plurality of lens elements, and the light from the light emitting elements is irradiated to the lens element side of the light emitting elements. A microlens that is condensed and incident on the lens element is formed, and a planar area of the microlens disposed opposite to the periphery of the lens element is equal to that of the microlens disposed opposite to the center of the lens element. It is characterized by being formed larger than the plane area.
According to this configuration, since the microlens having a large plane area can allow more light to be incident from the light emitting element, more light can be incident on the peripheral portion of the lens element. Thereby, the light quantity distribution from the center part to the peripheral part of the lens element becomes flat, and the periodic light quantity unevenness of the lens array can be eliminated.

On the other hand, a method for manufacturing a line head according to the present invention is a method for manufacturing a line head, in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion via a plurality of lens elements, Performing a lyophilic treatment on a region corresponding to the light emitting element on a substrate disposed between the lens element and a lyophobic treatment on a region other than the lyophilic treatment region; and the lyophilic treatment A step of applying a liquid material containing a microlens forming material to the region, and a step of curing the liquid material to form a first microlens and a second microlens. In the body applying step, liquid bodies having different volumes are applied to the region corresponding to the light emitting element, and the radius of curvature of the first microlens arranged opposite to the peripheral part of the lens element is the central part of the lens element. Is placed opposite to Than the radius of curvature of said second micro lenses, wherein the reduced form.
On the other hand, a method for manufacturing a line head according to the present invention is a method for manufacturing a line head, in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion via a plurality of lens elements, A step of performing lyophilic treatment on an area corresponding to the light emitting element on a substrate disposed between the lens element and lyophobic treatment on an area other than the lyophilic treatment area; and the lyophilic treatment A step of applying a liquid material containing a microlens forming material to the region, and a step of drying the liquid material to form a microlens. It is characterized by applying.
According to this configuration, microlenses having different curvatures can be easily formed by applying liquid materials having different volumes.

The liquid material applying step is preferably performed by discharging droplets containing the microlens forming material from a droplet discharge head.
According to this configuration, it is possible to accurately form microlenses having different curvatures.

A method of manufacturing a line head in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion via a plurality of lens elements, and is disposed between the light emitting elements and the lens elements. A step of applying a lyophilic process to a region corresponding to the light emitting element on the substrate and a lyophobic process to a region other than the lyophilic process region; A step of applying a liquid material; and a step of drying the liquid material to form a microlens, wherein the lyophilic processing region is formed with the lyophilic processing regions having different sizes. And
According to this configuration, microlenses having different curvatures can be easily formed by forming the lyophilic processing regions having different sizes.

On the other hand, the image forming apparatus of the present invention is characterized in that the line head manufactured using the above-described line head or the above-described method of manufacturing a line head is provided as an exposure unit.
According to this configuration, since it is possible to eliminate the periodic light amount unevenness of the lens array, it is possible to provide an image forming apparatus with excellent drawing quality.
The line head of the present invention is a line head that is formed by arranging a plurality of light emitting elements and irradiates light to an exposed portion through the plurality of lens elements, and is arranged between the lens elements of the light emitting elements. 1 microlens and a second microlens, wherein the radius of curvature of the first microlens arranged to face the periphery of the lens element is arranged to face the center of the lens element It is smaller than the radius of curvature of the second microlens.
The line head according to the present invention is a line head in which a plurality of light emitting elements are arranged and irradiates light to an exposed portion via the plurality of lens elements, and a microlens is disposed on the lens element side of the light emitting element. The curvature of the microlens disposed opposite to the periphery of the lens element is smaller than the curvature of the microlens disposed opposite to the center of the lens element. .

Embodiments of the present invention will be described below with reference to the drawings. In each drawing referred to below, the dimensions and the like of each component are appropriately changed and displayed for easy understanding of the drawing.
[First Embodiment]
First, the line head according to the first embodiment will be described with reference to FIG. The line head according to the first embodiment includes microlenses 13 and 14 that condense light from an organic EL element and enter the SL element 31a, and the curvature of the microlens 14 that is disposed opposite to the periphery of the SL element 31a. However, it is formed smaller than the curvature of the microlens 13 disposed opposite to the central portion of the SL element 31a.

(Line head module)
First, a line head module used as an exposure unit of the image forming apparatus will be described.
FIG. 1 is a side sectional view of a line head module. The line head module 101 according to the present embodiment includes a line head 1 in which a plurality of organic EL elements (not shown) and a microlens 12 are arranged and an SL element 31a that images the light from the line head 1 upright at an equal magnification. The arranged SL array 31 is fixed to the head case 52. In this line head module 101, light from the organic EL elements aligned and arranged on the line head 1 is collected by the microlens 12 and incident on the SL element 31 a constituting the SL array 31, and the outer peripheral surface of the photosensitive drum 41. In this case, the exposure is performed by forming an equal magnification image.

(Line head)
2A and 2B are diagrams schematically showing the line head, in which FIG. 2A is a bottom view and FIG. 2B is a side view. As shown in FIG. 2A, the line head 1 includes a light emitting element array 3A in which a plurality of organic EL elements 3 are arranged on a long and thin rectangular element substrate 2, and driving for driving the organic EL elements 3. A drive element group composed of the elements 4 and a control circuit group 5 that controls driving of these drive elements 4 (drive element groups) are integrally formed. In FIG. 2A, the organic EL elements 3 are arranged in one row, but may be arranged in two rows in a staggered manner. In this case, the pitch of the organic EL elements 3 in the longitudinal direction of the line head 1 can be reduced, and the resolution of the image forming apparatus can be improved.

  The organic EL element 3 includes at least an organic light emitting layer between a pair of electrodes, and emits light by supplying a current from the pair of electrodes to the light emitting layer. A power line 8 is connected to one electrode of the organic EL element 3, and a power line 7 is connected to the other electrode via a drive element 4. The drive element 4 is composed of a switching element such as a thin film transistor (TFT) or a thin film diode (TFD). When a TFT is adopted as the drive element 4, the power supply line 8 is connected to the source region, and the control circuit group 5 is connected to the gate electrode. The control circuit group 5 controls the operation of the drive element 4, and the drive element 4 controls the energization of the organic EL element 3. The detailed structure and manufacturing method of the organic EL element 3 and the driving element 4 will be described later.

As shown in FIG. 2B, the same number of microlenses 12 as the organic EL elements are formed on the bottom surface of the line head 1 in order to collect the light from the organic EL elements and make it incident on the SL elements. .
FIG. 8A is an enlarged view of a side cross section of the line head. As will be described later, the line head of the present embodiment extracts light through the substrate 2 from the organic EL element 3 formed on the upper surface of the substrate 2 (bottom emission method). On the lower surface of the substrate 2, a bank (partition wall) 18 having an opening 18a in an organic EL element formation region is formed. A microlens 12 made of a light transmitting material such as an acrylic resin is formed inside the opening 18a.

  In order to form the microlens 12, first, the inside of the opening 18a corresponding to the formation region of the organic EL element is subjected to a lyophilic process, and the surface of the bank 18 is subjected to a liquid repellent process. The lyophilic treatment can be performed by performing plasma treatment using oxygen gas, and the lyophobic treatment can be performed by performing plasma treatment using CF 4 gas. Next, using a droplet discharge head, a droplet containing a microlens forming material is discharged to the opening 18a. Thereafter, the discharged liquid material is cured to form the microlens 12.

  Here, the liquid droplets ejected from the liquid droplet ejection head do not adhere to the surface of the bank 18 subjected to the liquid repellent treatment, and adhere only to the opening 18a subjected to the lyophilic treatment. Therefore, the microlenses 12 having different plane areas can be formed by forming the lyophilic processing regions having different sizes. Even if droplets are ejected beyond the volume of the opening 18a, the liquid does not spread on the surface of the bank 18 subjected to the liquid repellent treatment, and rises like a dome inside the opening 18a. Therefore, the microlenses 12 having different curvatures can be formed by varying the droplet discharge amount.

  As the above-described droplet discharge head, it is desirable to employ a droplet discharge head that discharges droplets from a nozzle by changing the pressure in the liquid chamber using a piezoelectric element that generates mechanical vibrations when energized. Note that a liquid droplet discharge head that discharges liquid droplets from a nozzle by locally heating the liquid chamber with a heating element to generate bubbles may be adopted. In addition to this, a continuous method such as a charge control type and a pressure vibration type, an electrostatic suction method, and a method in which an electromagnetic wave such as a laser is irradiated to generate heat and a liquid material is discharged by the action of this heat generation are adopted. You can also.

Instead of providing the bank 18 in a region other than the lyophilic processing region, a SAM film containing a fluorine group (self-assembled film) may be formed. Since the surface of this SAM film exhibits liquid repellency, a microlens can be formed in the same manner as described above.
The formation position of the microlens 12 is not limited to the lower surface of the substrate 2 as long as it is on the light emitting side of the organic EL element 3. In particular, in order to allow as much light as possible to enter the microlens from the organic EL element, it is desirable to reduce the distance between the organic EL element and the microlens as much as possible.

(SL array)
FIG. 3 is a perspective view of the SL array. The SL array 31 is an array of SL elements 31a manufactured by Nippon Sheet Glass Co., Ltd. The SL element 31a is formed in a fiber shape having a diameter of about 0.28 mm. The SL elements 31a are arranged in a staggered manner, and the gap between the SL elements 31a is filled with a black silicone resin 32. Further, a frame 34 is arranged around the periphery, and an SL array 31 is formed.

  The SL element 31a has a parabolic refractive index distribution from the center to the periphery. For this reason, the light incident on the SL element 31a travels while meandering through the inside thereof at a constant period. By adjusting the length of the SL element 31a, it is possible to form an image upright at an equal magnification. If the SL elements 31a for erecting equal-magnification imaging are aligned, images formed by the adjacent SL elements 31a can be superimposed, and a wide range of images can be obtained. Therefore, the SL array of FIG. 3 can accurately form light from the entire line head.

(Micro lens)
FIG. 4 is an explanatory diagram of the light flux distribution of the line head and the light amount unevenness of the SL array. 4A is a plan view of the line head, FIG. 4B is a front sectional view of the line head and the SL array, and FIG. 4C is a graph showing the light quantity distribution of the SL array. .
Light emitted radially from an organic EL element (not shown) is collected by the microlens 12 shown in FIG. 4B and emitted to the SL element 31a. When the light is incident on the SL element 31a without being condensed by the microlens 12, the light transmission efficiency of the SL array is about 6% of the total light emission amount of the line head. Thus, the light transmission efficiency can be improved to at least 6% or more by entering the SL element 31a.

  Thus, since the light irradiated radially from the organic EL element is condensed by the microlens 12, the luminous flux distribution 12b of the emitted light from the microlens 12 is substantially spherical. In FIG. 4B, since each microlens 12 is formed in the same shape, the light flux distribution 12b from each microlens 12 has the same shape. On the other hand, one SL element 31 a is disposed opposite to the plurality of microlenses 12. And the emitted light from one SL element 31a has shown light quantity distribution 31b which halved the football.

  Since the SL array 31 is configured by arranging such SL elements 31a, periodic light amount unevenness shown in FIG. 4C occurs in the light emitted from the SL array 31. That is, a state in which the light amount at the center of each SL element 31a is large and the light amount at the peripheral edge is small periodically occurs along the arrangement direction of the SL elements 31a. Note that the level of unevenness in the amount of light in the entire SL array 31 is about ± 5%. If the photosensitive drum 41 shown in FIG. 1 is exposed using such a line head module with uneven light quantity, the drawing quality of the image forming apparatus is degraded.

FIG. 5 is an explanatory diagram of the light flux distribution of the line head and the light amount unevenness of the SL array according to the first embodiment. 5A is a plan view of the line head, FIG. 5B is a front sectional view of the line head and the SL array, and FIG. 5C is a graph showing the light amount distribution of the SL array. .
In the line head of the first embodiment, as shown in FIG. 5B, the curvature of each microlens is continuously changed. That is, the curvature of the microlens 14 disposed opposite to the peripheral portion of the SL element 31a is smaller than the curvature of the microlens 13 disposed opposite to the central portion of the SL element 31a. Note that microlenses having different curvatures can be formed by changing the discharge amounts of droplets containing microlens forming materials.

  FIG. 7A is an explanatory diagram of the relationship between the curvature of the microlens and the light condensing action. As shown in FIG. 7A, the curvature R2 of the microlens 14 is smaller than the curvature R1 of the microlens 13. In this case, the light emitted from the microlens 14 is narrowed near the optical axis as compared with the light emitted from the microlens 13. Therefore, as shown in FIG. 5B, the luminous flux distribution 13b of the outgoing light from the microlens 13 is substantially spherical, whereas the luminous flux distribution 14b of the outgoing light from the microlens 14 is substantially elliptical. It has become. Thereby, compared with the case where the curvature of each micro lens is equal, more light can be entered with respect to the peripheral part of SL element 31a. Therefore, it becomes possible to make the light quantity of the emitted light from the peripheral part of the SL element 31a equal to the light quantity of the emitted light from the center part of the SL element 31a. As a result, as shown in FIG. 5C, the light quantity distribution of the entire SL array 31 becomes flat, and periodic light quantity unevenness can be eliminated. The exposure quality of the image forming apparatus can be improved by exposing the photosensitive drum 41 shown in FIG. 1 using such a line head module having no light amount unevenness.

  The light reading angle of one SL element 31a shown in FIG. 5B is about ± 11 °. Therefore, when the light emitted from the line head 1 enters the SL element 31a beyond the angular range, the light does not contribute to image formation. Therefore, if the light emitted from the microlens 14 is narrowed to the vicinity of the optical axis as described above, the light incident on the SL element 31a within the above angle range can be significantly increased. Since the level of the light amount unevenness in the entire SL array 31 is about ± 5%, the light amount unevenness can be sufficiently eliminated by the configuration of the present embodiment.

[Second Embodiment]
Next, a line head according to a second embodiment will be described with reference to FIG.
FIG. 6 is an explanatory diagram of the light flux distribution of the line head and the light amount unevenness of the SL array according to the second embodiment. 6A is a plan view of the line head, FIG. 6B is a front sectional view of the line head and the SL array, and FIG. 6C is a graph showing the light quantity distribution of the SL array. . The line head according to the second embodiment is formed such that the plane area of the microlens 16 disposed opposite to the periphery of the SL element 31a is larger than the plane area of the microlens 15 disposed opposite to the center of the SL element 31a. It is what.

  In the line head according to the second embodiment, as shown in FIGS. 6A and 6B, the plane area of each microlens is continuously changed. That is, the plane area of the microlens 16 disposed opposite to the peripheral portion of the SL element 31a is larger than the plane area of the microlens 15 disposed opposite to the center of the SL element 31a. Note that microlenses having different plane areas can be formed by changing the areas of the lyophilic processing regions.

  FIG. 7B is an explanatory diagram of the relationship between the plane area of the microlens and the light condensing function. As shown in FIG. 7B, the plane area S2 of the microlens 16 is larger than the plane area S1 of the microlens 15. In this case, the microlens 16 can make more light incident from the organic EL element 3 than the microlens 15. Therefore, as shown in FIG. 6B, the luminous flux distribution 16b of the outgoing light from the microlens 16 has a larger area (stronger light) than the luminous flux distribution 15b of the outgoing light from the microlens 15. Yes. Thereby, compared with the case where the planar area of each microlens is equal, more light can be entered with respect to the peripheral part of SL element 31a. Therefore, it becomes possible to make the light quantity of the emitted light from the peripheral part of the SL element 31a equal to the light quantity of the emitted light from the center part of the SL element 31a. As a result, as shown in FIG. 6C, the light quantity distribution of the entire SL array 31 becomes flat, and periodic light quantity unevenness can be eliminated. The exposure quality of the image forming apparatus can be improved by exposing the photosensitive drum 41 shown in FIG. 1 using such a line head module having no light amount unevenness.

(Organic EL element and driving element)
Next, detailed configurations of the organic EL element and the driving element in the line head will be described with reference to FIGS.
In the case of a so-called bottom emission type in which the light emitted from the light emitting layer 60 is emitted from the pixel electrode 23 side, the light emitting light is extracted from the element substrate 2 side. Therefore, the element substrate 2 is transparent or translucent. Things are adopted. For example, glass, quartz, resin (plastic, plastic film) and the like can be mentioned, and a glass substrate is particularly preferably used.

In the case of a so-called top emission type in which the light emitted from the light emitting layer 60 is emitted from the cathode (counter electrode) 50 side, the emitted light is extracted from the sealing substrate side that is the opposite side of the element substrate 2. Therefore, either a transparent substrate or an opaque substrate can be used. Examples of the opaque substrate include a thermosetting resin and a thermoplastic resin in addition to a ceramic sheet such as alumina and a metal sheet such as stainless steel that has been subjected to an insulation treatment such as surface oxidation.
In the present embodiment, a bottom emission type is adopted, and therefore transparent glass is used for the element substrate 2.

  On the element substrate 2, a circuit unit 11 including a driving TFT 123 (driving element 4) connected to the pixel electrode 23 is formed, and an organic EL element 3 is provided thereon. The organic EL element 3 includes a pixel electrode 23 functioning as an anode, a hole transport layer 70 for injecting / transporting holes from the pixel electrode 23, a light emitting layer 60 made of an organic EL material, and a cathode 50 in this order. It is configured by being formed.

Here, when the organic EL element 3 and the driving TFT 123 (driving element 4) are shown in a schematic view corresponding to FIG. 2A, it is as shown in FIG. 8B. In FIG. 8B, the power supply line 7 is connected to the source / drain electrodes of the drive element 4, and the power supply line 8 is connected to the cathode 50 of the organic EL element 3.
In the organic EL element 3 having such a configuration, the holes injected from the hole transport layer 70 and the electrons from the cathode 50 are combined in the light emitting layer 60 as shown in FIG. By doing so, it emits light.

  In this embodiment, an inorganic partition wall 25 made of a lyophilic insulating material such as SiO 2 is formed on the pixel electrode 23, and an opening 25 a is formed in the inorganic partition wall 25. Here, since the inorganic partition wall 25 is made of an insulating material, in the functional layer provided so as to face the opening 25a as will be described later, no current flows through the portion covered with the inorganic partition wall 25, Therefore, the light emitting region, that is, the light emitting area is determined by the opening 25 a of the inorganic partition wall 25.

The pixel electrode 23 that functions as an anode is formed of a transparent conductive material, particularly in the case of a bottom emission type, and specifically, ITO is preferably used.
As a material for forming the hole transport layer 70, in particular, a dispersion of 3,4-polyethylenediosithiophene / polystyrene sulfonic acid (PEDOT / PSS), that is, 3,4-polyethylenedioxy in polystyrene sulfonic acid as a dispersion medium. A dispersion in which thiophene is dispersed and further dispersed in water is preferably used.
In addition, as a forming material of the positive hole transport layer 70, various things can be used, without being limited to the said thing. For example, a material obtained by dispersing polystyrene, polypyrrole, polyaniline, polyacetylene or a derivative thereof in an appropriate dispersion medium such as the aforementioned polystyrene sulfonic acid can be used.

  As a material for forming the light emitting layer 60, a known light emitting material capable of emitting fluorescence or phosphorescence is used. In this embodiment, for example, a light emitting layer whose emission wavelength band corresponds to red is adopted, but of course, a light emission layer whose emission wavelength band corresponds to green or blue may be adopted.

  Specific examples of the material for forming the light emitting layer 60 include (poly) fluorene derivative (PF), (poly) paraphenylene vinylene derivative (PPV), polyphenylene derivative (PP), polyparaphenylene derivative (PPP), and polyvinylcarbazole (PVK). ), Polythiophene derivatives, and polysilanes such as polymethylphenylsilane (PMPS) are preferably used. In addition, these polymer materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, and quinacridone. It can also be used by doping a low molecular weight material such as.

The cathode 50 is formed so as to cover the light emitting layer 60. For example, Ca is formed to a thickness of about 20 nm, and Al is formed thereon to a thickness of about 200 nm to form an electrode having a laminated structure, and the Al is reflected. It also functions as a layer.
Further, a sealing substrate (not shown) is stuck on the cathode 50 via an adhesive layer.

  In addition, the circuit unit 11 is provided below the organic EL element 3 as described above. The circuit unit 11 is formed on the element substrate 2. That is, a base protective layer 281 mainly composed of SiO 2 is formed on the surface of the element substrate 2 as a base, and a silicon layer 241 is formed thereon. A gate insulating layer 282 mainly composed of SiO 2 and / or SiN is formed on the surface of the silicon layer 241.

  In the silicon layer 241, a region overlapping with the gate electrode 242 with the gate insulating layer 282 interposed therebetween is a channel region 241a. The gate electrode 242 is a part of a scanning line (not shown). On the other hand, a first interlayer insulating layer 283 mainly composed of SiO 2 is formed on the surface of the gate insulating layer 282 that covers the silicon layer 241 and on which the gate electrode 242 is formed.

  Further, in the silicon layer 241, a low concentration source region 241b and a high concentration source region 241S are provided on the source side of the channel region 241a, while a low concentration drain region 241c and a high concentration drain are provided on the drain side of the channel region 241a. The region 241D is provided to form a so-called LDD (Light Doped Drain) structure. Among these, the high-concentration source region 241S is connected to the source electrode 243 through a contact hole 243a that opens over the gate insulating layer 282 and the first interlayer insulating layer 283. The source electrode 243 is configured as a part of a power supply line (not shown). On the other hand, the high-concentration drain region 241D is connected to the drain electrode 244 made of the same layer as the source electrode 243 through a contact hole 244a that opens through the gate insulating layer 282 and the first interlayer insulating layer 283.

  On the first interlayer insulating layer 283 on which the source electrode 243 and the drain electrode 244 are formed, for example, a planarizing film 284 mainly composed of an acrylic resin component is formed. The planarizing film 284 is formed of a heat-resistant insulating resin such as acrylic or polyimide, and has surface irregularities caused by the driving TFT 123 (driving element 4), the source electrode 243, the drain electrode 244, and the like. It is a well-known thing formed in order to eliminate.

  A pixel electrode 23 made of ITO or the like is formed on the surface of the planarizing film 284 and connected to the drain electrode 244 through a contact hole 23a provided in the planarizing film 284. That is, the pixel electrode 23 is connected to the high concentration drain region 241D of the silicon layer 241 through the drain electrode 244.

  On the surface of the planarization film 284 on which the pixel electrode 23 is formed, the pixel electrode 23 and the above-described inorganic partition wall 25 are formed, and on the inorganic partition wall 25, an organic partition wall 221 is formed. On the pixel electrode 23, the hole transport layer 70 and the light emitting layer 60 are formed inside the opening 25 a formed in the inorganic partition wall 25 and the opening 221 a formed in the organic partition wall 221, that is, in the pixel region. Are stacked in this order from the pixel electrode 23 side, thereby forming a functional layer.

  On the other hand, on the lower surface of the element substrate 2, a bank (partition wall) 18 having an opening 18a in an organic EL element formation region is formed. A microlens 12 made of a light transmitting material such as acrylic resin is formed inside the opening 18a.

(Line head manufacturing method)
Next, a manufacturing method of the line head having such a configuration will be described.
First, as shown in FIG. 9A, a base protective layer 281 is formed on the surface of the element substrate 2, and a polysilicon layer or the like is further formed on the base protective layer 281. The circuit unit 11 is formed.
Next, a transparent conductive film to be the pixel electrode 23 is formed of ITO or the like so as to cover the entire surface of the element substrate 2. Then, by patterning this conductive film, the pixel electrode 23 that is electrically connected to the drain electrode 244 through the contact hole 23a of the planarizing film 284 is formed.

  Next, an insulating material such as SiO 2 is formed on the pixel electrode 23 and the planarizing film 284 by a CVD method or the like to form a partition layer (not shown), followed by a known photolithography technique or etching technique. Is used to pattern the partition wall layer. Thereby, as shown in FIG. 9B, the opening 25a is formed for each pixel region of each organic EL element to be formed, and at the same time, the inorganic partition wall 25 is formed.

Next, as shown in FIG. 9C, an organic partition 221 is formed with a resin or the like at a predetermined position of the inorganic partition 25, specifically, a position surrounding the pixel region.
Next, a region showing lyophilicity and a region showing liquid repellency are formed on the surface of the element substrate 2. In the present embodiment, each region is formed by plasma processing. Specifically, the plasma treatment includes a preheating step, a lyophilic step for making the surface of the organic partition wall 221 and the wall surface of the opening 221a, the electrode surface 23c of the pixel electrode 23, and the surface of the inorganic partition wall 25 lyophilic. The liquid barrier layer 221 includes a liquid repellent process for making the upper surface of the organic partition wall 221 and the wall surface of the opening 221a liquid repellent, and a cooling process.

  That is, the base material (element substrate 2 including a bank or the like) is heated to a predetermined temperature, for example, about 70 to 80 ° C., and then a plasma treatment (O 2 plasma treatment) using oxygen as a reaction gas at atmospheric pressure as a lyophilic process. Do. Next, a plasma treatment (CF4 plasma treatment) using methane tetrafluoride as a reaction gas under atmospheric pressure is performed as a lyophobic process, and then the base material heated for the plasma treatment is cooled to room temperature. Liquidity and liquid repellency are imparted to a predetermined location.

  In this CF4 plasma treatment, the electrode surface 23c of the pixel electrode 23 and the inorganic partition wall 25 are somewhat affected, but ITO, which is the material of the pixel electrode 23, and SiO2, TiO2, etc., which are the constituent materials of the inorganic partition wall 25, etc. Has poor affinity for fluorine, so that the hydroxyl group imparted in the lyophilic step is not substituted with the fluorine group, and the lyophilic property is maintained.

  Next, the hole transport layer 70 is formed by a hole transport layer forming step. In this hole transport layer forming step, an inkjet method is particularly preferably employed as the droplet discharge method. That is, by this ink jet method, the hole transport layer forming material is selectively disposed on the electrode surface 23c and applied. Thereafter, drying treatment and heat treatment are performed to form the hole transport layer 70 on the electrode 23. As a material for forming the hole transport layer 70, for example, a material obtained by dissolving the PEDOT: PSS in a polar solvent such as isopropyl alcohol is used.

  Here, in forming the hole transport layer 70 by the ink jet method, first, the ink jet head (not shown) is filled with a hole transport layer forming material, and the discharge nozzle of the ink jet head is formed in the inorganic partition wall 25. Opposite the electrode surface 23c located in the opening 25a, and moving the ink jet head and the base material (element substrate 2) relative to each other, droplets with a controlled liquid amount per droplet from the discharge nozzle are applied to the electrode surface 23c. Discharge. Next, the discharged droplets are dried and the hole transport layer 70 is formed by evaporating the dispersion medium and the solvent contained in the hole transport layer material.

At this time, the droplet discharged from the discharge nozzle spreads on the electrode surface 23c that has been subjected to the lyophilic treatment, fills the opening 25a of the inorganic partition wall 25, and faces the opening 25a. On the other hand, droplets are repelled and do not adhere to the upper surface of the organic barrier 221 that has been subjected to the liquid repellent treatment. Therefore, even if the liquid droplet is displaced from a predetermined discharge position and a part of the liquid droplet is applied to the surface of the organic partition wall 221, the surface is not wetted by the liquid droplet, and the repelled liquid droplet is the inorganic partition wall 25. Into the opening 25a.
In addition, after this positive hole transport layer formation process, it is preferable to carry out in inert gas atmospheres, such as nitrogen atmosphere and argon atmosphere, in order to prevent oxidation and moisture absorption of various formation materials and the formed element.

Next, as shown in FIG. 10A, the light emitting layer 60 is formed by the light emitting layer forming step. In the light emitting layer forming step, as in the formation of the hole transport layer 70, an ink jet method which is a droplet discharge method is suitably employed. That is, the light emitting layer forming material is ejected onto the hole transport layer 70 by an ink jet method, and then subjected to a drying process and a heat treatment, whereby the light emitting layer is formed in the opening 221a formed in the organic partition 221, that is, on the pixel region. 60 is formed.
The functional layer in the present invention can be formed by the formation process of the hole transport layer 70 and the formation process of the light emitting layer 60 described above.

  Next, as shown in FIG. 10B, the cathode 50 is formed by a cathode layer forming step. The cathode 50 generally employs a laminated structure such as an electron injection layer and a conductive layer in order to cause the EL element to emit light efficiently. For example, a metal material such as aluminum can be used. Unlike the formation of the hole transport layer 70 and the light emitting layer 60, the formation of the cathode 50 is performed by vapor deposition or sputtering, so that the formation material is not selectively disposed only in the pixel region. The forming material is provided on almost the entire surface of the element substrate 2. Therefore, in the present embodiment, the element substrate 2 and a metal mask (not shown) are aligned and the cathode 50 is formed by vapor deposition or sputtering, so that the cathode is formed around the substrate as shown in FIG. 50 is not formed.

Thereafter, as shown in FIG. 10C, the sealing substrate 30 is bonded by a sealing process. In this sealing step, a transparent adhesive 40 is applied between the transparent sealing substrate 30 and the element substrate 2, and the sealing substrate 30 and the element substrate 2 are bonded to each other so that bubbles do not enter.
In the above-described embodiment, an example in which an organic EL element is used as the EL element formed in the line head 1 of the present invention has been described. However, an inorganic EL element may be used instead. .

  Next, as shown in FIG. 8A, a bank (partition wall) 18 having an opening 18 a in an organic EL element formation region is formed on the lower surface of the element substrate 2. Then, the microlens 12 is formed inside the opening 18a by a droplet discharge method. Note that the bank 18 and the microlens 12 may be formed on the lower surface of the element substrate 2 before the circuit portion 11 and the like are formed on the upper surface of the element substrate 2.

(Usage of line head module)
Next, the usage pattern of the line head module of this embodiment will be described.
The line head module of this embodiment is used as an exposure device in an image forming apparatus. In this case, the line head module is disposed so as to face the photosensitive drum, and the light from the line head is imaged on the photosensitive drum by the SL array and used at an equal magnification.

(Tandem image forming device)
First, a tandem image forming apparatus will be described.
FIG. 11 is a schematic configuration diagram of a tandem image forming apparatus, and reference numeral 80 in FIG. 11 denotes the image forming apparatus. This image forming apparatus 80 is an exposure apparatus for four photosensitive drums (image carriers) 41K, 41C, 41M, and 41Y having the same configuration corresponding to the line head modules 101K, 101C, 101M, and 101Y of the present invention. Are arranged in a tandem system.

  The image forming apparatus 80 includes a driving roller 91, a driven roller 92, and a tension roller 93. The intermediate transfer belt 90 is stretched around these rollers so as to circulate and drive in the direction of the arrow (counterclockwise) in FIG. Is. Photosensitive drums 41K, 41C, 41M, and 41Y are arranged at predetermined intervals with respect to the intermediate transfer belt 90. These photosensitive drums 41K, 41C, 41M, and 41Y have a photosensitive layer as an image carrier on the outer peripheral surface thereof.

  Here, K, C, M, and Y in the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are for black, cyan, magenta, and yellow, respectively. The meanings of these symbols (K, C, M, Y) are the same for the other members. The photosensitive drums 41K, 41C, 41M, and 41Y are driven to rotate in the arrow direction (clockwise) in FIG. 11 in synchronization with the driving of the intermediate transfer belt 90.

  Around each photosensitive drum 41 (K, C, M, Y), charging means (corona charger) 42 for uniformly charging the outer peripheral surface of the photosensitive drum 41 (K, C, M, Y), respectively. (K, C, M, Y) and rotation of the photosensitive drum 41 (K, C, M, Y) on the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) The line head module 101 (K, C, M, Y) of the present invention that sequentially performs line scanning in synchronism with each other is provided.

  Further, a developing device 44 (K, C) that applies a toner as a developer to the electrostatic latent image formed by the line head module 101 (K, C, M, Y) to form a visible image (toner image). , M, Y) and a primary transfer roller 45 (K) as transfer means for sequentially transferring the toner image developed by the developing device 44 (K, C, M, Y) to the intermediate transfer belt 90 which is a primary transfer target. , C, M, Y) and a cleaning device 46 (K, C, M) as a cleaning means for removing toner remaining on the surface of the photosensitive drum 41 (K, C, M, Y) after being transferred. , Y).

  Here, each line head module 101 (K, C, M, Y) is installed such that the arrangement direction of the organic EL elements is along the bus line of the photosensitive drum 41 (K, C, M, Y). The emission energy peak wavelength of each line head module 101 (K, C, M, Y) and the sensitivity peak wavelength of the photosensitive drum 41 (K, C, M, Y) are set so as to substantially match. Yes.

  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 regulating blade, and the developing roller is brought into contact with or pressed against the photosensitive drum 41 (K, C, M, Y), whereby the photosensitive drum 41 (K, C, M, A developer is attached in accordance with the potential level of Y) and developed as a toner image.

  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). Primary transfer is sequentially performed on the transfer belt 90. The toner images that are sequentially superimposed on the intermediate transfer belt 90 to become a full color are secondarily transferred to the recording medium P such as paper by the secondary transfer roller 66 and further pass through the fixing roller pair 61 that is a fixing unit. Then, the toner image is fixed on the recording medium P and then discharged onto a paper discharge tray 68 formed on the upper part of the apparatus by a pair of paper discharge rollers 62.

  In FIG. 11, 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 that feeds the recording media P from the paper feed cassette 63 one by one, and 65 denotes secondary transfer. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion of the roller 66; a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 90; A cleaning blade 67 serves as a cleaning unit that removes toner remaining on the surface of the intermediate transfer belt 90 after the secondary transfer.

(4-cycle image forming apparatus)
Next, a four-cycle image forming apparatus will be described.
FIG. 12 is a schematic configuration diagram of a four-cycle image forming apparatus image. In FIG. 12, an image forming apparatus 160 includes, as main constituent members, a rotary developing device 161, a photosensitive drum 165 that functions as an image carrier, and a line head according to the present embodiment that functions as an image writing unit (exposure unit). A module 167, an intermediate transfer belt 169, a paper conveyance path 174, a fixing unit heating roller 172, and a paper feed tray 178 are provided.

  The developing device 161 is configured such that the developing rotary 161a rotates in the direction of arrow A about the shaft 161b. The inside of the development rotary 161a is divided into four, and image forming units for four colors of yellow (Y), cyan (C), magenta (M), and black (K) are provided. Reference numerals 162a to 162d are arranged in the image forming units for the four colors. The developing rollers rotate in the direction of the arrow B, and the toner supply rollers 163a to 163d rotate in the direction of the arrow C. Reference numerals 164a to 164d are regulating blades that regulate the toner to a predetermined thickness.

  In FIG. 12, reference numeral 165 denotes a photosensitive drum that functions as an image carrier as described above, 166 a primary transfer member, and 168 a charger. Reference numeral 167 denotes a line head module according to the present embodiment that functions as an image writing unit (exposure unit). The photosensitive drum 165 is rotationally driven in the direction of arrow D, which is the direction opposite to the developing roller 162a, by a drive motor (not shown), for example, a step motor.

  The intermediate transfer belt 169 is stretched between the driving roller 170a and the driven roller 170b. The driving roller 170 a is connected to the driving motor of the photosensitive drum 165 and transmits power to the intermediate transfer belt 169. That is, the drive roller 170a of the intermediate transfer belt 169 is rotated in the direction of arrow E which is the opposite direction to the photosensitive drum 165 by the drive motor.

  The paper transport path 174 is provided with a plurality of transport rollers, a pair of paper discharge rollers 176, and the like, so that the paper is transported. An image (toner image) on one side carried on the intermediate transfer belt 169 is transferred to one side of the paper at the position of the secondary transfer roller 171. The secondary transfer roller 171 is brought into contact with and separated from the intermediate transfer belt 169 by a clutch. When the clutch is turned on, the secondary transfer roller 171 is brought into contact with the intermediate transfer belt 169 so that an image is transferred onto a sheet.

  The sheet on which the image has been transferred as described above is then subjected to a fixing process by a fixing device having a fixing heater H. The fixing device is provided with a heating roller 172 and a pressure roller 173. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. When the paper discharge roller pair 176 rotates in the reverse direction from this state, the paper reverses its direction and advances in the double-sided printing conveyance path 175 in the direction of arrow G. 177 is an electrical component box, 178 is a paper feed tray for storing paper, and 179 is a pickup roller provided at the outlet of the paper feed tray 178.

  For example, a low-speed brushless motor is used as a drive motor for driving the transport roller in the paper transport path. For the intermediate transfer belt 169, a step motor is used because color misregistration correction is required. Each of these motors is controlled by a signal from a control means (not shown).

  In the state shown in FIG. 12, a yellow (Y) electrostatic latent image is formed on the photosensitive drum 165, and a high voltage is applied to the developing roller 162a, whereby a yellow image is formed on the photosensitive drum 165. Is done. When the yellow back side and front side images are all carried on the intermediate transfer belt 169, the development rotary 161a rotates 90 degrees in the direction of arrow A.

  The intermediate transfer belt 169 rotates once and returns to the position of the photosensitive drum 165. Next, two images of cyan (C) are formed on the photosensitive drum 165, and this image is carried on the yellow image carried on the intermediate transfer belt 169. Thereafter, the 90-degree rotation of the development rotary 161 and the one-rotation process after the image is carried on the intermediate transfer belt 169 are repeated in the same manner.

For carrying four color images, the intermediate transfer belt 169 rotates four times, and then the rotation position is further controlled to transfer the image onto the sheet at the position of the secondary transfer roller 171. The sheet fed from the sheet feed tray 178 is conveyed by the conveyance path 174, and the color image is transferred to one side of the sheet at the position of the secondary transfer roller 171. The sheet on which the image is transferred on one side is reversed by the discharge roller pair 176 as described above, and stands by on the conveyance path. Thereafter, the sheet is conveyed to the position of the secondary transfer roller 171 at an appropriate timing, and the color image is transferred to the other side. The housing 180 is provided with an exhaust fan 181.
The image forming apparatus including the line head module of the present invention is not limited to the above, and various modifications can be made.

It is side surface sectional drawing of a line head module. It is the figure which showed the line head typically. It is a perspective view of SL array. It is explanatory drawing of the light beam distribution of a line head, and the light quantity nonuniformity of SL array. It is explanatory drawing of the light beam distribution of the line head which concerns on 1st Embodiment, and the light quantity nonuniformity of SL array. It is explanatory drawing of the light beam distribution of the line head which concerns on 2nd Embodiment, and the light quantity nonuniformity of SL array. It is explanatory drawing of the relationship between the curvature and flat area of a micro lens, and a condensing effect | action. It is explanatory drawing of an organic EL element and a drive element. It is explanatory drawing of the manufacturing process of a line head. It is explanatory drawing of the manufacturing process of a line head. 1 is a schematic configuration diagram of a tandem image forming apparatus. 1 is a schematic configuration diagram of a four-cycle image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Line head 13 ... Micro lens 14 ... Micro lens 31 ... Lens array 31a ... Lens element

Claims (5)

A line head comprising a plurality of light emitting elements arranged and irradiating light to an exposed portion via a plurality of lens elements,
A first microlens and a second microlens that condense light from the light emitting element and enter the lens element between the light emitting element and the lens element ;
The radius of curvature of the first microlens arranged opposite to the periphery of the lens element is smaller than the radius of curvature of the second microlens arranged opposite to the center of the lens element. Line head. A method of manufacturing a line head comprising a plurality of light emitting elements arranged, and irradiating light on an exposed portion via a plurality of lens elements,
On a substrate disposed between said light emitting element and the lens element, together subjected to lyophilic treatment to a region corresponding to the light emitting element, a step of performing liquid-repellent treatment to the region other than the lyophilic processing region,
Applying a liquid containing a microlens forming material to the lyophilic region;
Curing the liquid material to form a first microlens and a second microlens , and
In the liquid material application step, liquid materials having different volumes are applied to regions corresponding to the light-emitting elements, and the radius of curvature of the first microlens disposed opposite to the periphery of the lens element is equal to that of the lens element. A method of manufacturing a line head, wherein the second microlens disposed opposite to the center is formed to have a radius of curvature smaller than that of the second microlens . The method of manufacturing a line head according to claim 2 , wherein the liquid material applying step is performed by discharging a droplet including a material for forming the microlens from a droplet discharge head. An image comprising the line head according to claim 1 or 2 or the line head manufactured by using the line head manufacturing method according to claim 3 as an exposure unit. Forming equipment. A line head comprising a plurality of light emitting elements arranged and irradiating light to an exposed portion via a plurality of lens elements,
A first microlens and a second microlens are provided between the lens elements of the light emitting element ,
The radius of curvature of the first microlens arranged opposite to the periphery of the lens element is smaller than the radius of curvature of the second microlens arranged opposite to the center of the lens element. Line head.

Images