JP5206518B2 - Organic electroluminescence device, light emitting device array, exposure head, and image forming apparatus - Google Patents

Description

  The present invention relates to an organic electroluminescent element, a light emitting element array, an exposure head, and an image forming apparatus.

  As the light emitting element, an organic EL element disclosed in Patent Document 1 is known. The organic EL element disclosed in Patent Document 1 is configured as follows for the purpose of realizing long life with high luminance light emission.

  The organic EL element of Patent Document 1 includes a plurality of light emitting units 3-1, 3-2. . . . 3-n, and each light-emitting unit forms a single equipotential surface. . . . It is characterized by being partitioned by 4-n.

JP 2003-45676 A

  An object of the present invention is to improve light emission luminance.

  An organic electroluminescent device according to claim 1 of the present invention is a first electrode, a second electrode that forms a pair with the first electrode, and transmits light, and the gap between the first electrode and the second electrode. A light-emitting layer that emits light when a voltage is applied between the first electrode and the second electrode, and is disposed on the opposite side of the light-emitting layer from the second electrode as viewed from the second electrode; A light shielding portion that shields part of the light emitted from the light emitting layer toward the second electrode.

In the organic electroluminescent element according to claim 1 of the present invention, the light shielding portion further has light reflectivity for reflecting light from the light emitting layer.

In the organic electroluminescent element according to claim 1 of the present invention, the light shielding portion is further made of metal.

In the organic electroluminescent element according to claim 1 of the present invention, the light shielding portion is further made of Al.

In the organic electroluminescent element according to claim 1 of the present invention, the first electrode further has light reflectivity for reflecting light from the light emitting layer.

In the organic electroluminescence device according to claim 1 of the present invention, furthermore, the light shielding member and the first electrode has a resonator structure.

Emitting element array according to claim 2 of the present invention, an organic electroluminescent device according to claim 1 are arranged in a staggered manner.

Exposure head according to claim 3 of the present invention includes a light emitting device array of claim 2, the light generated by the light emitting element array is condensed, and the imaging device array for imaging an irradiated surface, Is provided.

An image forming apparatus according to a fourth aspect of the present invention comprises: a latent image holding body that holds a latent image; and the exposure head according to claim 3 that forms a latent image by irradiating the latent image holding body with light. And a developing device for developing the latent image formed by the exposure head.

  According to the configuration of the first aspect of the present invention, the light emission luminance can be improved as compared with the case where the light shielding portion is not provided.

According to the configuration of the first aspect of the present invention, the light emission luminance can be improved as compared with the case where the light shielding portion does not have light reflectivity.

According to the structure of Claim 1 of this invention, compared with the case where the light shielding part is not formed with the metal, it becomes easy to take the electrical connection of the exterior and the 2nd electrode.

According to the structure of Claim 1 of this invention, compared with the case where the light-shielding part is not formed with Al, light extraction efficiency can be improved.

According to the configuration of the first aspect of the present invention, the directivity (the property that the intensity varies depending on the direction when light or the like is output in the space) compared to the case where the first electrode does not have light reflectivity. improves.

According to the configuration of the first aspect of the present invention, the directivity is improved as compared with the case where the resonator structure is not provided.

According to the configuration of the second aspect of the present invention, a light-emitting array having a high density can be obtained as compared with the case where they are not arranged in a staggered pattern.

According to the configuration of the third aspect of the present invention, high-definition image writing can be performed as compared with the case where this configuration is not provided.

According to the configuration of the fourth aspect of the present invention, a high-definition image can be obtained as compared with the case where the configuration is not provided.

FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present embodiment. FIG. 2 is a schematic view showing the arrangement of the exposure head according to this embodiment. FIG. 3 is a schematic diagram schematically showing a state in which light emitted from the exposure head according to the present embodiment is imaged on the photosensitive drum. FIG. 4 is a schematic view seen from the light emitting surface side, showing the configuration of the exposure head according to the present embodiment. FIG. 5 is a schematic diagram showing the configuration of the organic EL element according to this embodiment. FIG. 6 is a schematic diagram in which the reflective electrode has a concave lens structure in the organic EL element according to the present embodiment. FIG. 7 is a schematic diagram in which the reflective electrode has a concave lens structure in the organic EL element according to the present embodiment. FIG. 8 is a schematic diagram for comparing a configuration having the light shielding mask 74 with a configuration not having the light shielding mask 74. FIG. 9 is a schematic view showing a configuration of an organic EL element according to a modified example having a bottom emission structure. FIG. 10 is a schematic diagram illustrating a configuration of an organic EL element according to Comparative Example 1. FIG. 11 is a table showing the evaluation results of Comparative Example 1 and Examples 1 to 3.

Below, an example of an embodiment concerning the present invention is described based on a drawing.
(Configuration of image forming apparatus according to the present embodiment)
First, the configuration of the image forming apparatus according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present embodiment.

  The image forming apparatus 10 includes a recording medium accommodating unit 12 that accommodates a recording medium P such as paper, an image forming unit 14 that forms a toner image on the recording medium P, and recording from the recording medium accommodating unit 12 to the image forming unit 14. Conveying means 16 that conveys the medium P, a fixing device 18 that fixes the toner image formed by the image forming unit 14 to the recording medium P, and a recording medium P on which the toner image is fixed by the fixing device 18 is discharged. A medium discharge unit (not shown).

  The image forming unit 14 includes image forming units 22C, 22M, 22Y, and 22K that form toner images of cyan (C), magenta (M), yellow (Y), and black (K), and an image forming unit 22C. , 22M, 22Y, 22K, an intermediate transfer belt 24 as an example of an intermediate transfer member to which a toner image is transferred, and a toner image formed by the image forming units 22C, 22M, 22Y, 22K as an intermediate transfer belt 24. A primary transfer roll 26 as an example of a primary transfer member that transfers the toner image to the recording medium P, and a secondary transfer roll 28 as an example of a secondary transfer member that transfers the toner image transferred to the intermediate transfer belt 24 to the recording medium P. ing.

  Each of the image forming units 22C, 22M, 22Y, and 22K has a photosensitive drum 30 that rotates in one direction (clockwise in FIG. 1) as an image carrier on which an electrostatic latent image is formed on the surface. .

  Around each photosensitive drum 30, a charging device 32 for charging the surface of the photosensitive drum 30 in order from the upstream side in the rotation direction of the photosensitive drum 30, and the surface of the charged photosensitive drum 30 are exposed to expose the photosensitive drum 30. An exposure head 34 as an exposure device that forms an electrostatic latent image on the surface of the drum 30; a developing device 36 that develops the electrostatic latent image formed on the surface of the photosensitive drum 30 to form a toner image; and a toner A removing device 40 that removes toner remaining on the surface of the photosensitive drum 30 after the image is transferred to the intermediate transfer belt 24 is provided.

  The intermediate transfer belt 24 is supported by a counter roll 42, a drive roll 44, and a support roll 46 that face the secondary transfer roll 28, and circulates in one direction (counterclockwise in FIG. 1) while being in contact with the photosensitive drum 30. It is supposed to move.

  The primary transfer roll 26 faces the photosensitive drum 30 with the intermediate transfer belt 24 interposed therebetween. Between the primary transfer roll 26 and the photosensitive drum 30, a primary transfer position where the toner image on the photosensitive drum 30 is primarily transferred to the intermediate transfer belt 24 is formed. At the primary transfer position, the primary transfer roll 26 transfers the toner image on the surface of the photoconductive drum 30 to the intermediate transfer belt 24 by a pressing force and an electrostatic force.

  The secondary transfer roll 28 faces the opposing roll 42 with the intermediate transfer belt 24 interposed therebetween. A secondary transfer position where the toner image on the intermediate transfer belt 24 is secondarily transferred to the recording medium P is formed between the secondary transfer roll 28 and the opposing roll 42.

  The conveying means 16 includes a sending roll 50 that sends out the recording medium P accommodated in the recording medium accommodating portion 12, and a conveying roll pair 52 that sandwiches and conveys the recording medium P sent out by the sending roll 50 to the secondary transfer position. I have.

  The fixing device 18 is disposed downstream in the transport direction from the secondary transfer position, and fixes the toner image transferred at the secondary transfer position to the recording medium P.

  A conveyance belt 54 as an example of a conveyance member that conveys the recording medium P to the fixing device 18 is disposed downstream of the secondary transfer position in the conveyance direction and upstream of the fixing device 18 in the conveyance direction.

  With the above configuration, in the image forming apparatus 10 according to the present embodiment, the recording medium P sent out from the recording medium storage unit 12 is first sent to the secondary transfer position by the transport roll pair 52.

  On the other hand, the toner images of the respective colors formed by the image forming units 22C, 22M, 22Y, and 22K are superimposed on the intermediate transfer belt 24 to form a color image. The color image formed on the intermediate transfer belt 24 is transferred to the recording medium P sent to the secondary transfer position.

  The recording medium P to which the toner image is transferred is conveyed to the fixing device 18, and the transferred toner image is fixed by the fixing device 18. The recording medium P on which the toner image is fixed is discharged to a recording medium discharge unit (not shown). As described above, a series of image forming operations are performed.

  The configuration of the image forming apparatus is not limited to the above-described configuration. For example, a direct transfer type image forming apparatus that does not have an intermediate transfer member may be used, and various configurations may be employed.

(Configuration of exposure head)
Next, the configuration of the exposure head will be described. 2 and 3 are schematic views showing the arrangement of the exposure head according to this embodiment.

  As shown in FIGS. 2 and 3, each exposure head 34 includes a substrate 60 formed in an elongated shape in the main scanning direction, an organic EL element array 62 as an example of a light emitting element array, and an organic EL element array 62. And a Selfoc lens array 64 as an example of an imaging element array that collects the light generated by the above and focuses the light on the photosensitive drum 30.

  The organic EL element array 62 includes an organic EL element 70 as an example of an organic electroluminescent element. A plurality of organic EL elements 70 are arranged along the main scanning direction on the substrate 60 according to the number of pixels (number of dots). Specifically, the organic EL elements 70 are arranged in a staggered manner as shown in FIG.

  Specifically, the staggered arrangement is as follows. Two rows in which the organic EL elements 70 are arranged at a predetermined pitch along the main scanning direction are arranged in parallel. The pitch of the organic EL elements 70 in each row is the same, and one row is shifted by about a half pitch in the main scanning direction with respect to the other row. By adopting the staggered arrangement in this way, the number of elements per unit length is increased as compared with the configuration without the staggered arrangement.

  The substrate 60 is provided with a plurality of driver ICs 66 as an example of drive circuits for driving the organic EL elements 70. The driver IC 66 drives the plurality of organic EL elements 70 individually.

  The selfoc lens array 64 is configured by arranging a plurality of rod lenses 64 </ b> A, and is arranged on the light emission side of the plurality of organic EL elements 70.

  In the SELFOC lens array 64, the rod lenses 64A are two-dimensionally arranged so as to form an erecting equal-magnification image with a plurality of rod lenses 64A for one dot. Therefore, the emitted light from each organic EL element 70 is imaged on the surface of the photosensitive drum 30 via the corresponding plurality of selfoc lens arrays 64. As described above, the photosensitive drum 30 is exposed by the light emitted from the organic EL element 70 to form a latent image.

  The optical lens combined with the organic EL element 70 is not limited to the SELFOC lens array 64, and a cylindrical lens may be combined. Further, a microlens may be bonded on each organic EL element 70.

(Configuration of organic EL element)
Next, the configuration of the organic EL element will be described. FIG. 5 is a schematic diagram showing the configuration of the organic EL element according to this embodiment.

  The organic EL (electroluminescent) element 70 includes a reflective electrode 71 as an example of a first electrode, a transparent electrode 73 as an example of a second electrode paired with the first electrode, the first electrode, An organic EL layer 72 as an example of a light emitting layer disposed between the second electrode and an example of a light shielding unit disposed on the opposite side of the light emitting layer from the second electrode. A light-shielding mask 74.

  The reflective electrode 71 is formed on the substrate 60. The reflective electrode 71 is used as an anode when the organic EL element 70 has a top emission structure.

  As described later, in order to form a resonator structure with the light shielding mask 74, the reflective electrode 71 is preferably made of a highly reflective metal or a highly reflective amorphous alloy. Examples of the highly reflective metal include Al, Ag, Mo, W, Ni, and Cr. Examples of the highly reflective amorphous alloy include NiP, NiB, CrP, and CrB. The material of the reflective electrode 71 is not limited to the above material.

  The reflective electrode 71 may have a concave lens structure as shown in FIGS. In this concave lens structure, a base formation layer 76 made of an organic or inorganic material is formed in advance on a substrate 60 formed of glass, and a crystal anisotropic etching method, It is formed by processing a concave pattern using a reactive ion etching method using a density plasma or a micro-imprinting method, and depositing or sputtering an electrode material on the concave pattern. As shown in FIG. 6, the shape of the recess may be configured to be curved in a circular hole shape, or may be configured to be bent in a V shape as illustrated in FIG. 7.

  Thus, by using a concave lens structure, in a later-described resonance structure, the light condensing property to the light extraction portion is improved, and the directivity of light emission and the strength are improved.

  The organic EL layer 72 includes a hole injection layer and a hole transport layer formed on the reflective electrode 71 side, an electron injection layer and an electron transport layer formed on the transparent electrode 73 side, a hole injection layer, a hole transport layer, and an electron injection. And a light emitting layer formed between the layer and the electron transport layer.

  These organic layers are formed by laminating organic thin films made of low-molecular or high-molecular organic materials. Organic thin film formation methods include CVD (Chemical Vapor Deposition), molecular beam deposition, dipping, spin coating, casting, printing, inkjet, and spraying. You may do it.

  Examples of the material for the hole injection layer include low molecular weight materials such as phthalocyanines (including CuPc) or indanthrene compounds, MTDATA (4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine ), Polyaniline, polymer materials such as PEDOT / PSS (polyethylenedioxythiophene / polystyrene sulfonate), and the like.

  Examples of the material for the hole transport layer include triphenyldiamine derivatives, polyphylyl derivatives, stilbene derivatives, oxadiazole derivatives, tetraphenylenediamine derivatives, triphenylamine derivatives, carbazole derivatives, stilbene derivatives, arylhydrazone derivatives, porphyrin compounds, and the like. Can be used.

  As the light-emitting layer, chelate type organometallic complexes, polynuclear or condensed aromatic ring compounds, perylene derivatives, coumarin derivatives, styrylarylene derivatives, silole derivatives, oxazole derivatives, oxathiazole derivatives, oxadiazole derivatives, polyparaphenylene derivatives, poly Paraphenylene vinylene derivatives, polythiophene derivatives, polyacetylene derivatives, and the like can be given.

  As the electron transport layer, oxadiazole derivatives, triazole derivatives, triazine derivatives, phenylquinoxalines, thiophene derivatives, chelate type organometallic complexes, and the like are used.

  As the electron injection layer, an alkali metal, an alkaline earth metal or an alloy containing them, an alkali metal fluoride, or an aluminum quinolinol complex doped with an alkaline earth metal may be used.

The transparent electrode 73 formed on the organic EL layer 72 has a light transmitting property and is used as a cathode. The transparent electrode 73 is laminated by, for example, a sputtering method. The transparent electrode 73 is formed using a conductive metal oxide such as SnO ₂ , In ₂ O ₃ , ITO, or IZO: Al.

  When the transparent electrode 73 is used as a cathode, it is desirable to increase the electron injection efficiency by using the uppermost layer of the organic EL layer 72 as an electron injection layer. The transparent electrode 73 preferably has a transmittance of preferably 50% or more, more preferably 80% or more with respect to light having a wavelength of 400 to 800 nm. The transparent electrode 73 has a thickness of usually 50 nm or more, preferably 50 nm to 1 μm, more preferably 100 to 300 nm.

  As shown in FIG. 4, the transparent electrode 73 and the reflective electrode 71 are each formed in a band shape, and a light emitting portion 78 is formed at the intersection. The reflective electrode 71 is divided for each light emitting unit 78, and the current flowing through the light emitting unit 78 is individually controlled. The transparent electrode 73 is formed in common for all the light emitting portions 78.

  The bank (partition wall) 75 is for element isolation, and is made of a polyimide or acrylic resin. The bank 75 is formed by, for example, photolithography. The bank 75 may be coated with an insulating film after being coated with a reflective metal. In this case, light leakage to the outside of the organic EL element 70 is reduced, and the light emission intensity is increased.

  The light shielding mask 74 blocks part of the light emitted from the organic EL layer 72 toward the transparent electrode 73, and restricts the exit as a light extraction portion from which light is extracted from the transparent electrode 73.

  The light shielding mask 74 is preferably made of a highly reflective metal or a highly reflective amorphous alloy in order to form a resonator structure between the light emitted from the organic EL layer 72 and the reflective electrode 71. Examples of the highly reflective metal include Al, Ag, Mo, W, Ni, and Cr. Examples of the highly reflective amorphous alloy include NiP, NiB, CrP, and CrB. The material of the light shielding mask 74 is not limited to the above materials.

  The light shielding mask 74 is formed with an opening 74A for allowing a part of the light to pass therethrough. Examples of the method of forming the opening 74A of the light shielding mask 74 include a method of forming a holed pattern by vapor deposition and sputtering after covering the hole forming portion with the mask, and etching using photolithography.

  Here, as shown in FIG. 8A, in the configuration without the light shielding mask 74 as described above, the light generated by the organic EL layer having the same area as the light extraction portion 174A for extracting light is irradiated. On the other hand, as shown in FIG. 8B, by providing the light shielding mask 74, light from the organic EL layer 72 having an area larger than the opening 74A (light extraction portion) is irradiated. Luminous brightness (brightness per unit area) is improved.

  In addition, since the light shielding mask 74 has electroconductivity, you may make it contact with the transparent electrode 73 and use it as an electrode collectively. This facilitates electrical connection to the outside.

In the present embodiment, a resonator structure may be formed by the light shielding mask 74 and the reflective electrode 71.
For example, assuming that a light emitting region exists at the interface between the reflective electrode 71 and the organic EL layer 72, the distance L between the light shielding mask 74 and the reflective electrode 71 with respect to the light extraction wavelength λ is L = n (λ / 2): n = 1,2, ...
And it is sufficient.

  In the resonator structure, superposition of waves propagating at a wavelength corresponding to the resonator length of the resonator occurs, and light emission increases and directivity improves when viewed in unit angles and unit spectra. Thereby, even when the irradiation port is made small, high luminance is maintained.

  Further, as shown in FIG. 9, the organic EL element 70 may have a bottom emission structure. In that case, the light shielding mask 74, the transparent electrode 73, the organic EL layer 72, and the reflective electrode 71 are arranged on the transparent substrate 60 in this order. In this case, the transparent electrode 73 is an anode and the reflective electrode 71 is a cathode.

〔Example〕
Next, examples will be described. The present invention is not limited to these examples.

<Example 1 (top emission)>
In Example 1, as shown in FIG. 5, first, a bank 75 is formed on a cleaned glass substrate 60 using photolithography. The formation pattern of the banks 75 is staggered in order to increase the density of the organic EL elements 70. Then, reflective electrode 71 was formed by vapor-depositing 100 nm of Al.

  Next, after ITO is formed by 200 nm sputtering in the pixel formation portion surrounded by the bank 75, an organic functional layer is formed in the order of PEDOT / PSS, a hole transport layer, and a light emitting layer by an ink jet method. It was.

  Next, after forming a transparent electrode 73 (cathode) by sputtering Ca: 30nm and ITO: 250nm, a deposition mask is formed at a position corresponding to the opening 74A, and a perforated pattern is formed by Al deposition. A light-shielding mask 74 having the property was formed.

  A voltage was applied between the transparent electrode 73 and the reflective electrode 71 of the organic EL element according to this example to cause the organic EL layer 72 to emit light, and the light emission intensity was measured on the light extraction surface side of the light shielding mask 74. As a comparison, the light emission intensity of an organic EL element produced on a glass substrate without the light shielding mask 74 was measured.

  As a result, the organic EL element 70 of Example 1 had higher emission intensity than the organic EL element without the light shielding mask 74. That is, it has been found that the light collection efficiency can be increased by the configuration of the organic EL element of Example 1.

<Example 2 (bottom emission)>
First, as shown in FIG. 9, a dot pattern corresponding to the opening 74A is formed on the cleaned glass substrate 60 by photolithography, and then an Al pattern is formed on the pixel forming portion by sputtering. This pattern has a staggered arrangement in order to increase the density of the organic EL element 70. Thereafter, the light shielding mask 74 having reflectivity is formed by lifting off.

  Next, in order to fill the hole of the light shielding mask 74 and make it flat, PMMA (polymethyl methacrylate) was spin-coated to form an insulating film 77.

  Next, a resist (polyimide) was spin-coated, and a bank 75 was formed in accordance with the position of the light shielding mask 74 by photolithography. Next, a transparent electrode 73 (anode) was formed on the pixel formation portion by sputtering ITO.

  Next, the organic EL layer 72 was formed in the order of PEDOT / PSS, the hole transport layer, and the light emitting layer by the inkjet method in the pixel formation portion surrounded by the bank 75.

  Finally, the reflective electrode 71 (cathode) was deposited in the order of Ca and Al to form an organic EL element.

  With this structure, it was found that the aperture ratio is reduced because light is extracted from the substrate side on which the circuit is formed, and the light emission efficiency is reduced as compared with Example 1.

<Example 3 (top emission + lens structure)>
First, as shown in FIG. 6, PMMA was applied onto a cleaned glass substrate 60 by a spin coater, and then heated to 200 ° C. to soften PMMA. Thereafter, a mold mold on which a spherical convex mold was formed was pressed onto the resin and slowly cooled to transfer a hemispherical concave mold shape onto the resin, thereby forming the base forming layer 76. This pattern has a staggered arrangement in order to increase the density of the organic EL elements 70.

  Next, a polyimide bank 75 was formed in a shape surrounding the hemispherical concave mold using photolithography, and then Al was evaporated to 100 nm, and ITO was sputtered to 200 nm to form a lens-type reflective electrode 71 (anode).

  Next, the organic EL layer 72 was formed in the order of PEDOT / PSS, the hole transport layer, and the light emitting layer by the inkjet method in the pixel formation portion surrounded by the bank 75.

  Next, after depositing Ca to 20 nm, ITO was sputtered to 200 nm to form a transparent electrode 73 (cathode), and then Al was deposited on the transparent electrode 73 to form a light-shielding mask 74 having reflectivity.

  In this element structure, it was found that the light emission intensity and directivity were improved by the effect of the lens structure as compared with Example 1.

<Example 4 (top emission + lens structure)>
First, as shown in FIG. 7, PMMA was applied on a cleaned glass substrate 60 by a spin coater, and then heated to 200 ° C. to soften PMMA. Thereafter, a mold mold in which a convex mold having a triangular cross section was pressed onto the resin and slowly cooled to form a base forming layer 76 having a triangular cross section on the resin. This pattern is staggered to increase the density of the organic EL elements 70.

  Next, a polyimide bank 75 was formed in a shape surrounding the hemispherical concave mold using photolithography, and then Al was deposited by 100 nm, and ITO was sputtered by 200 nm to form a reflective electrode 71 (anode).

  Next, the organic EL layer 72 was formed in the order of PEDOT / PSS, the hole transport layer, and the light emitting layer by the inkjet method in the pixel formation portion surrounded by the bank.

  Next, after depositing 20 nm of Ca, ITO is sputtered to 200 nm to form a transparent electrode 73 (cathode), and then an Al pattern with a hole formed in the center is deposited on the top by mask deposition, thereby improving reflectivity. A shading mask 74 having the same was formed.

  In this element structure, it was found that the light emission intensity and directivity were improved by the effect of the lens structure as compared with Example 1.

(Comparative Example 1)
First, as shown in FIG. 10, a bank 75 is formed on a cleaned glass substrate 60 using photolithography. Thereafter, ITO 251 was sputtered to form an electrode 171 (anode).

  Next, the organic EL layer 72 was formed in the order of PEDOT / PSS, the hole transport layer, and the light emitting layer by the inkjet method in the pixel formation portion surrounded by the bank 75.

  Next, after depositing Ca by 20 nm, ITO was sputtered by 200 nm to form a transparent electrode 73 (cathode), thereby obtaining a comparative element.

(Evaluation)
The luminance was measured in the produced top emission type organic electroluminescence device. Table 1 shows the relative luminance when Comparative Example 1 is 1.

As shown in Table 1 of FIG. 11, compared to Comparative Example 1, Example 1 having a light-shielding mask 74 having reflectivity improved the luminance by 1.4 times. Further, in Examples 3 and 4 having a lens structure, the luminance was improved by 1.9 times and 1.8 times, respectively.
The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 30 Photosensitive drum (Image holding body)
34 Exposure Head 36 Developing Device 62 Organic EL Element Array (Light Emitting Element Array)
64 Selfoc lens array (imaging element array)
70 Organic EL element 71 Reflective electrode (first electrode)
72 Organic EL layer (light emitting layer)
73 Transparent electrode (second electrode)
74 Shading mask (light shielding part)

Claims (4)

A first electrode;
A second electrode paired with the first electrode and transmitting light;
A light emitting layer that is disposed between the first electrode and the second electrode, and emits light when a voltage is applied between the first electrode and the second electrode;
A light shielding portion disposed on the side opposite to the light emitting layer arrangement side when viewed from the second electrode, and shielding a part of light emitted from the light emitting layer to the second electrode side;
A substrate,
An underlying layer formed on the substrate and having a plurality of recesses on the surface;
With
The light shielding portion has light reflectivity for reflecting light from the light emitting layer, and has an opening through which light from the light emitting layer is extracted, and is formed of Al as a metal,
The first electrode has a light reflecting property to reflect light from the light emitting layer, and is formed in a concave portion on the surface of the base forming layer , and a concave lens that collects the reflected light to the opening. Has a structure,
The light shielding member and the first electrode have a resonator structure,
A partition is provided between the plurality of recesses on the surface of the foundation forming layer so as to sandwich the first electrode,
A side surface of the partition wall is coated with a reflective material that reflects light from the light emitting layer,
The light emitting layer, the second electrode, and the light shielding part are organic electroluminescent elements formed on the first electrode between the partition walls in this order .   The light emitting element array in which the organic electroluminescent element of Claim 1 is arrange | positioned in zigzag form. The light emitting element array according to claim 2;
An imaging element array for condensing the light generated by the light emitting element array and forming an image on an irradiated surface;
An exposure head comprising: A latent image holding body for holding the latent image;
The exposure head according to claim 3, wherein the latent image holding member is irradiated with light to form a latent image;
A developing device for developing a latent image formed by the exposure head;
An image forming apparatus comprising:

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