JP2008269792A - Organic electroluminescent device and line head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent device wherein uniform emission having no unevenness is obtained by uniforming the film thickness of an organic functional layer in a pixel region containing a plurality of light emitting elements, and a line head. <P>SOLUTION: This organic electroluminescent device 1 is equipped with the light emitting element 200 containing the organic functional layer 40 held between a pair of electrodes 41, 54, the pixel region 71 formed by disposing a plurality of the light emitting elements 200, and banks 50 partitioning the pixel region 71, on a substrate P. The bank 50 is formed so that the width of the pixel region 71 in its short side direction becomes larger as it goes toward the both end sides from its center part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element and a line head.

  In recent years, an organic electroluminescence element (hereinafter referred to as an organic EL element) having a structure in which a functional layer made of the functional material is sandwiched between a pair of electrodes, particularly an organic EL element using an organic light emitting material as a functional material has been developed. Has been done.

As such a functional material patterning method, there is known a method of patterning a functional material by a droplet discharge method, a dispenser method, or the like in which a functional material such as an organic fluorescent material is made into ink and the ink is discharged onto a substrate. (For example, see Patent Documents 1 to 6). Specifically, a droplet discharge head having a nozzle row in which a plurality of nozzles are arranged is used, and the droplet discharge head is scanned from the nozzle while scanning a substrate having a bank (partition) formed on the surface. A method of forming a functional layer on a substrate by ejecting ink into an area (pixel area) surrounded by a bank is employed. Such a method is more effective than spin coating or the like in terms of material utilization efficiency because micro-order droplets can be arranged in a predetermined region.
JP 2004-130161 A JP 2003-217842 A JP 2001-189192 A JP 2001-76872 A JP 2000-323276 A

  However, a common bank is formed on a substrate having an aspect ratio (ratio of the length of the short side to the length of the long side) of, for example, 2 or more so as to partition a pixel region including a plurality of light emitting elements, and the pixel region When the organic functional layer is formed using the above-described patterning method, the ink (functional material) arranged in the opening region is dried toward the center of the opening region along the long side direction and the opening along the short side direction. A difference in speed occurs with the drying speed toward the center of the part, resulting in uneven drying. As a result, the film thickness of the organic functional layer constituting each light emitting element becomes non-uniform, and there is a problem that uneven light emission occurs.

  The present invention has been made in view of such circumstances, and in a pixel region including a plurality of light-emitting elements, organic electroluminescence that achieves uniform light emission with uniform thickness of the organic functional layer is achieved. An object is to provide an element and a line head.

The present invention employs the following configuration in order to solve the above problems.
That is, the organic electroluminescence element of the present invention includes a light emitting element including an organic functional layer sandwiched between a pair of electrodes on a substrate, a pixel region in which a plurality of the light emitting elements are disposed, and a partition of the pixel region. The bank is formed such that the width of the pixel region in the short side direction increases from the center of the pixel region toward both ends. To do.

  According to the organic electroluminescence element of the present invention, the functional liquid for forming the organic functional layer disposed in the pixel region is held more at both end portions than at the central portion. Thereby, the drying speed in the central part of the pixel area can be relatively increased, the drying speed in the entire planar area of the pixel area becomes constant, and the film thickness of the organic functional layer is made uniform. Therefore, uniform light emission without unevenness in light emission can be obtained with a plurality of light emitting elements arranged in the pixel region.

Moreover, in the said organic electroluminescent element, it is preferable that the said board | substrate becomes rectangular shape and the length of a long side direction is 2 times or more of the length of a short side direction.
Here, when a rectangular substrate whose long side is twice or more the length of the short side is used, there is a possibility that the film thickness uniformity of the organic light emitting layer cannot be obtained in the pixel region. Therefore, if the present invention is adopted, a particularly great effect can be obtained.

In the organic electroluminescence element, it is preferable that the bank is formed so as to gradually widen the width of the pixel region in the short side direction.
According to this configuration, the opening portion continuously changes from the central portion toward both end portions, and the distribution amount of the forming material (functional liquid) of the organic functional layer disposed in the opening shape can be adjusted favorably. The film thickness uniformity of the organic functional layer can be improved.

Moreover, in the said organic electroluminescent element, it is desirable that the said organic functional layer is formed by the liquid phase method.
Moreover, in the said organic electroluminescent element, it is desirable for the said organic functional layer to laminate | stack various functional layers.

  The line head of the present invention is characterized by comprising the above-mentioned organic electroluminescence element.

  According to the line head of the present invention, since the line head is composed of the organic electroluminescence element, uniform light without unevenness in light emission can be obtained and the reliability becomes high.

(Organic electroluminescence device)
Hereinafter, embodiments of the organic electroluminescence element (hereinafter referred to as an organic EL element) of the present invention will be described with reference to the drawings. This embodiment shows a part of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in each figure shown below, in order to make each layer and each member the size which can be recognized on drawing, the scale is varied for each layer and each member.

  FIG. 1 is a circuit configuration diagram of the organic EL element of the present embodiment, and FIG. 2 is a plan view showing a schematic configuration of the organic EL element according to the present embodiment. FIG. 3 is a diagram showing a schematic configuration in a cross section of the organic EL element taken along line AA in FIG. The organic EL element of this embodiment is suitably used as a line head in an image forming apparatus as will be described later.

  As shown in FIG. 1, the organic EL element 1 includes a plurality of scanning lines 31, a plurality of signal lines 32 extending in a direction intersecting with the scanning lines 31, and the signal lines 32 on a transparent substrate. A plurality of common power supply lines 33 extending in parallel are wired, and each light emitting element region A is provided at each intersection of the scanning lines 31 and the signal lines 32.

  For the signal line 32, a data side driving circuit 72 including a shift register, a level shifter, a video line, an analog switch, and the like is provided. On the other hand, a scanning side driving circuit 73 including a shift register, a level shifter, and the like is provided for the scanning line 31. Further, each of the light emitting element regions A is supplied from a switching TFT (thin film transistor) 42 to which a scanning signal (power) is supplied to the gate electrode via the scanning line 31 and from the signal line 32 via the switching TFT 42. The storage capacitor cap that holds the image signal to be stored, the driving TFT 43 to which the image signal held by the holding capacitor cap is supplied to the gate electrode, and the common power supply line 33 are electrically connected via the driving TFT 43 A pixel electrode (a pair of electrodes) 41 into which a driving current sometimes flows from the common power supply line 33, and an organic layer (organic functional layer) 40 sandwiched between the pixel electrode 41 and the cathode (a pair of electrodes) 54, Is provided.

  Under such a configuration, when the scanning line 31 is driven and the switching TFT 42 is turned on, the potential (power) of the signal line 32 at that time is held in the holding capacitor cap, and the state of the holding capacitor cap is reached. Accordingly, the on / off state of the driving TFT 43 is determined. Then, current (power) flows from the common power supply line 33 to the pixel electrode 41 through the channel of the driving TFT 43 and further flows to the cathode 54 through the organic layer 40, so that the organic layer 40 has an amount of current flowing therethrough. Emits light in response to.

  Further, when the planar structure of the organic EL element 1 shown in FIG. 2 is seen, the organic EL element 1 is provided with a common bank 50 that partitions the pixel region 71 on a long and thin rectangular substrate P having an aspect ratio of 2 or more. In the pixel area 71, a plurality of light emitting elements 200 constituting each light emitting element area A are provided. The light emitting element 200 is formed to the vicinity of both ends of the opening 50a of the common bank 50.

(Cross-section structure)
Next, the cross-sectional structure of the organic EL element 1 will be described. As shown in FIG. 3, the driving TFT 43 is provided on the substrate P, and the light emitting element 200 is formed through a plurality of insulating films formed to cover the driving TFT 43. The light emitting element 200 is mainly composed of the organic layer 40 provided in the pixel region 71 defined by the common bank 50, and the organic layer 40 is sandwiched between the pixel electrode 41 and the cathode 54.

In the case of the top emission type organic EL element as in the present embodiment, the substrate P is configured to extract light from the side where the light emitting element 200 is disposed. Therefore, in addition to a transparent substrate such as glass, an opaque substrate is used. Can also be used. Examples of opaque substrates include ceramics such as alumina, metal sheets such as stainless steel that have been subjected to insulation treatment such as surface oxidation, thermosetting resins and thermoplastic resins, and films thereof (plastic films). It is done.
The pixel electrode 41 can be formed of an appropriate conductive material such as a metal material. For example, a Cr film, an Au film, a Ti / ITO laminated film, or the like can be suitably used.

The pixel electrode 41 is electrically connected to the driving TFT 43 through a contact hole formed in the second interlayer insulating film 24.
The driving TFT 43 includes a source region 43, a drain region 43b and a channel region 43c formed in the semiconductor layer 21, and a gate electrode 143A facing the channel region 43c via the gate insulating film 22 formed on the surface of the semiconductor layer. And the main constituent. A first interlayer insulating film 23 covering the semiconductor layer 21 and the gate insulating film 22 is formed, and drain electrodes 36 are respectively formed in contact holes 34 and 35 that penetrate the first interlayer insulating film 23 and reach the semiconductor layer 21. The source electrode 38 is buried, and each electrode is conductively connected to the drain region 43 b and the source region 43. The second interlayer insulating film 24 is formed on the first interlayer insulating film 23, and a part of the pixel electrode 41 is embedded in a contact hole penetrating the second interlayer insulating film 24. Thus, the pixel electrode 41 and the drain electrode 36 are conductively connected, whereby the driving TFT 43 and the pixel electrode 41 are electrically connected.

  An inorganic bank 49 is formed on the pixel electrode 41. In the inorganic bank 49, an opening 49 a is formed on the pixel electrode 41, and the opening 49 a constitutes the light emitting element region A. The inorganic bank 49 separates the plurality of light emitting elements 200 independently. As a material for forming the inorganic bank 49, an insulating inorganic material such as silicon dioxide is used. In addition, as a material which forms the inorganic bank 49, what combined the inorganic substance and the organic substance may be used.

On the inorganic bank 49, the common bank 50 that partitions and forms a pixel region 71 including a plurality of light emitting element regions A is formed.
In the present embodiment, the opening 50 a (pixel region 71) of the common bank 50 is set in an oval shape in a plan view, and like the substrate P, the aspect ratio (with respect to the length in the short side direction) is set. The ratio of the length in the long side direction) is 2 or more. As a material for forming the common bank 50, for example, an insulating organic material such as polyimide or acrylic can be used. The thickness (height) of the common bank 50 can be formed in the range of 1 μm to 4 μm, and preferably about 2 μm. If the thickness is less than 1 μm, the common bank 50 becomes thinner than the thickness of the organic layer 40 and overflows outside the common bank 50 at the time of application, and the organic layer 40 may not be accurately formed in the common bank 50. On the other hand, if the thickness exceeds 4 μm, the step coverage of the cathode 54 may not be ensured. Moreover, the length of the common bank 50 in the longitudinal direction can be formed, for example, in a range of 10 mm to 1000 mm, and particularly preferably about 350 mm.

  The common bank 50 is formed such that the opening 50a increases the width of the pixel region 71 in the short side direction from the center of the pixel region 71 toward both ends. Further, the opening 50a of the common bank 50 gradually increases in width from the central portion toward both end portions. With this configuration, the opening 50a continuously changes from the central portion toward both ends, and by adjusting the amount of the functional liquid as the forming material of the organic layer 40 disposed in the opening 50a, As will be described later, the organic layer 40 is formed with a uniform film thickness by making the speed at which the functional liquid dries substantially constant in the pixel region 71.

  Specifically, in the present embodiment, the length (width) in the short direction of the common bank 50 can be formed in the range of 0.3 mm to 2 mm, and the shortest portion is set to about 0.5 mm. Further, the longest length (width) of the common bank 50 is set to about 2.0 mm.

  The organic layer 40 provided in the pixel region 71 partitioned in such a common bank 50 is formed by a jet dispenser method described later. Although details will be described later, when the functional liquid constituting the organic layer 40 is applied in the opening 50a of the common bank 50, the functional liquid is substantially omitted at the center and both ends of the opening 50a during the drying process. Dry at the same speed. Therefore, the organic layer 40 having very high flatness is formed in the opening 50a defined by the common bank 50.

  The organic layer 40 has a configuration in which a hole injection layer 40A and a light emitting layer 40B are stacked. The hole injection layer 40A is a layer provided for the purpose of improving the charge transport property to the light emitting layer 40B and enhancing the light emission efficiency. As a material for forming the hole injection layer 40A, for example, a polythiophene derivative, a polypyrrole derivative or the like, or a doping thereof The body is used. Specifically, a dispersion of 3,4-polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) or the like is used. Examples of the solvent used in this dispersion include isopropyl alcohol (IPA), n-butyl alcohol, γ-butyrolactone, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI) and derivatives thereof. And polar solvents such as glycols such as carbitol acetate and butyl carbitol acetate.

Further, the light emitting layer 40B combines the holes injected from the pixel electrode 41 through the hole injection layer 40A and the electrons injected from the cathode 54 to generate fluorescence.
Specific examples of the material for forming the light emitting layer 40B include (poly) fluorene derivative (PF), (poly) paraphenylene vinylene derivative (PPV), polyphenylene derivative (PP), polyparaphenylene derivative (PPP), and polyvinylcarbazole (PVK). ), Polythiophene derivatives, polymethylphenylsilane (PMPS), and the like.
Further, these polymer materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, nile red, coumarin 6, quinacridone. It can also be used by doping a low molecular weight material such as.

  The cathode 54 is formed on the substrate P so as to cover the upper surface of the common bank 50 and the wall surface forming the side surface of the common bank 50. As a material for forming the cathode 54, a transparent conductive material such as ITO is used.

  Further, an electron injection layer may be provided between the cathode 54 and the light emitting layer 40B. The electron injection layer serves to inject electrons into the light emitting layer 40B. Materials for forming the electron transport layer include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorenone derivatives , Diphenyldicyanoethylene and derivatives thereof, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline and derivatives thereof, and the like can be used.

  A protective layer may be formed on the upper layer side of the cathode 54. By providing such a protective layer, the effect of preventing the cathode 54 from being corroded during the manufacturing process can be obtained, and it can be formed of an inorganic compound, for example, a silicon compound such as silicon oxide, silicon nitride, or silicon nitride oxide. . By covering the cathode 54 with a protective layer made of an inorganic compound, entry of oxygen or the like into the cathode 54 made of an inorganic oxide can be satisfactorily prevented.

(Manufacturing method of organic EL element)
Here, the manufacturing method of the organic EL element 1 will be described with reference to the drawings, and the reason why the organic EL element 1 includes the organic layer 40 having a uniform film thickness will be described. In the following description, the steps up to the step of forming the pixel electrode 41 are the same as in the prior art, and thus the description thereof is omitted. Further, illustration of the driving TFT 43 and the like formed on the substrate P is omitted.

  First, the inorganic bank 49 is formed on the substrate P made of glass and on the pixel electrode 41 formed in a predetermined pattern as shown in FIG. Specifically, the film is formed by a high-density plasma film forming method such as an ECR sputtering method, an ion plating method, or a vacuum evaporation method. After forming the material for forming the inorganic bank 49, etching is performed through a resist mask to form an opening 49 a on the pixel electrode 41. The light emitting element region A can be defined by the opening 49a.

  Next, the common bank 50 is formed as shown in FIG. Specifically, the material for forming the common bank 50 is applied on the substrate P on which the material for forming the inorganic bank 49 is formed by spin coating, ink jetting, jet dispenser, needle dispenser, or the like. Then, the common bank 50 surrounding the pixel region 71 can be formed by exposing and developing using photolithography technology to form the opening 50a.

  Here, when the organic layer 40 is formed, a lyophilic region showing lyophilicity with respect to the functional liquid constituting the organic layer 40 and a lyophobic region showing lyophobic properties are formed on the substrate P. Specifically, the region showing lyophilicity is the surface of the pixel region 71 and the inorganic bank 49, and lyophilicity is imparted to the surface by plasma treatment using, for example, oxygen as a processing gas. The region exhibiting liquid repellency is the upper surface of the common bank 50 and imparts liquid repellency to the surface by plasma treatment using, for example, tetrafluoromethane (tetrafluoromethane) as a processing gas. When the common bank 50 is formed from a fluorine-containing resin material, plasma treatment for imparting liquid repellency is not necessary.

  Subsequently, the organic layer 40 is formed in the common bank 50. First, the hole injection layer 40A constituting the organic layer 40 is formed by a jet dispenser method.

  Specifically, as shown in FIGS. 5A to 5C, the functional liquid is applied from the dispenser D, and the common bank 50 is scanned from one end to the other end in the longitudinal direction (long side direction). . That is, in the pixel region 71, the liquid droplets F (functional liquid) are applied by a certain amount so as to overlap each other. At this time, the droplet F is repelled by the liquid repellency applied to the upper surface of the common bank 50, and the droplet F fills the entire pixel region 71 surrounded by the common bank 50 as shown in FIG. Become so. In the organic EL element 1 according to the present embodiment, the width in the short side direction of the pixel region 71 increases from the center of the pixel region 71 toward both end sides. Accordingly, a larger amount of the functional liquid is held on both end portions than on the central portion side of the opening 50a.

  In the present embodiment, a dispersion of 3,4-polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) was used as the functional liquid that constitutes the hole injection layer 40A. As an application condition at this time, the nozzle inner diameter of the dispenser D (see FIG. 5) can be in the range of 0.05 to 0.35 mm, and it is particularly preferable to use a nozzle of about 0.25 mm. In addition, the opening time (application time) of the electromagnetic valve of the forming material can be performed in the range of 1.0 to 3.0 msec, particularly preferably about 1.2 msec. Further, the opening / closing stroke of the solenoid valve can be performed in the range of 100 to 350 μm, and particularly preferably about 200 μm. The coating pitch can be in the range of 0.1 to 3 mm, and is preferably about 1.0 mm. The liquid pressure is preferably in the range of 0.002 to 0.02 MPa, particularly preferably about 0.01 MPa.

  Subsequently, the applied functional liquid of the applied hole injection layer 40A is dried. As this drying method, it is possible to carry out by a known method such as natural drying, warm drying, and reduced pressure drying.

  In general, the functional liquid disposed in the opening section partitioned by the bank starts to dry from the end side of the opening section, and gradually becomes dry on the center side. When a difference occurs in the speed at which the functional liquid dries in this way, the solute in the functional liquid (forming material for the hole injection layer) is dispersed in the undried functional liquid (opening central side), so that The amount of solute contained in the functional liquid is relatively increased. Then, the film thickness of the organic layer (hole injection layer 40A) 40 formed after drying becomes thicker at the center than at both ends of the opening, and the organic layer (hole injection layer 40A) 40 becomes thicker. May cause a difference in film thickness. In this case, only the light emitting element formed in the central part of the opening with relatively high flatness can be used effectively, and the light emitting element formed on both ends of the opening may cause uneven light emission. Therefore, it becomes a defective element and cannot contribute to light emission.

  In particular, when the hole injection layer 40A is formed in the pixel region 71 defined by the oval opening 50a having an aspect ratio of 2 or more, like the organic EL element 1 according to the present embodiment, the opening The difference in the drying speed of the functional liquid between the both end portions and the center portion in the long side direction of 50a may increase the film thickness uniformity of the hole injection layer 40A.

  However, in the organic EL element 1 according to the present embodiment, since the width in the short side direction of the pixel region 71 increases from the center of the pixel region 71 toward both ends as described above, the opening 50a in the pixel region 71 is. More functional liquid is held at both end portions than in the central portion. Thereby, the drying speed of the functional liquid in the central part of the pixel area 71 can be relatively increased, and the drying speed in the entire planar area of the pixel area 71 becomes constant. Therefore, in the hole injection layer 40A composed of the functional liquid dried at a constant speed, the solute does not flow in the functional liquid as described above. Therefore, the hole injection layer 40A having a uniform film thickness can be formed in the pixel region 71 (see FIG. 4D).

  Subsequently, the light emitting layer 40B is formed on the hole injection layer 40A. Specifically, the functional liquid droplet F ′ containing the material for forming the light emitting layer 40B is applied in the common bank 50 in the same manner as the hole injection layer 40A described above (see FIG. 4D). Then, the light emitting layer 40B can be formed by performing a drying process. Here, since the hole injection layer 40A formed in the pixel region 71 has a uniform film thickness as described above, the light emitting layer 40B formed thereon also has a film thickness in the pixel region 71. The organic layer 40, which is made uniform and includes the hole injection layer 40A and the light emitting layer 40B, has a uniform film thickness in the pixel region 71 as a whole. In addition, since the common bank 50 that partitions the pixel region 71 is formed as described above, the forming material (functional liquid) of the organic layer 40 can be easily applied to a predetermined position by a predetermined amount. If necessary according to the use of the organic EL element 1, a color filter layer may be continuously formed on the organic layer 40. In this case, since the organic layer 40 has a uniform thickness, the color filter layer formed thereon can also have a uniform thickness.

  The organic layer 40 can also be formed using a needle dispenser method in which a functional liquid is continuously applied. As an application condition at this time, the inner diameter of the nozzle can be in the range of 0.05 to 0.35 mm, and it is particularly preferable to carry out with a nozzle of about 0.25 mm. The substrate gap can be in the range of 20 to 100 μm, and preferably about 50 μm. The drawing speed can be 10 to 200 mm / sec, and preferably 10 mm / sec. The discharge flow rate is preferably in the range of 0.01 to 3 μl / sec, and particularly preferably about 0.1 μl / sec. In addition to the jet dispenser method and the needle dispenser method, non-contact coating methods such as an inkjet method can be used.

  Then, a cathode 54 is formed on the organic layer 40. Specifically, it can be formed by vapor deposition, sputtering, CVD, or the like. In particular, the vapor deposition method is preferable in that damage to the light emitting layer 40B due to heat can be prevented.

  And a protective layer is formed in the area | region on the board | substrate P containing the common bank 50, and also a light emitting element and a protective layer are sealed using a sealing member. About this sealing process, since a well-known process can be applied, the details are omitted. Note that the sealing step is preferably performed in an inert gas atmosphere such as nitrogen, argon, or helium. If it is carried out in the atmosphere, when a defect such as a pinhole has occurred in the cathode 54, water or oxygen may enter the cathode 54 from the defective portion and the cathode 54 may be oxidized, which is not preferable.

  As described above, in the organic EL element 1 according to this embodiment, the width of the opening 50a is increased from the center of the pixel region 71 toward both ends. With this configuration, the functional liquid disposed in the pixel region 71 can be retained more at both ends than in the center in the step of forming the organic layer 40. Thereby, the drying speed in the center part of a pixel area can be raised relatively, and the drying speed in the whole plane area | region of the pixel area 71 can be made constant. Therefore, the film thickness of the organic layer 40 can be made uniform. Therefore, the light emitting elements 200 arranged in the pixel region 71 have no uneven light emission, and uniform light emission can be obtained, and the organic EL element 1 having excellent display quality can be realized.

It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention.
The organic EL element of each embodiment described above can be applied to a monochrome display. Moreover, the light emitting layer (organic layer 40) of the organic EL element of each of the above-described embodiments is made of, for example, a white light emitting material, and the light (white light) emitted from each of the light emitting element regions A is subjected to a color filter. It is also possible to form a full color display by converting to red light, green light and blue light respectively. In this case, since the film thickness of the light emitting layer 40 is uniform, it is possible to provide a full color display organic EL element having excellent display quality. Such organic EL elements for full-color display include cellular phones, electronic books, projectors, personal computers, digital still cameras, television receivers, viewfinder type or monitor direct view type video tape recorders, car navigation devices, pagers, electronic It can be suitably used as image display means for devices such as notebooks, calculators, word processors, workstations, videophones, POS terminals, touch panels, etc. With such a configuration, uniform emission can be obtained without uneven emission. It is possible to provide an electronic device including a display portion that can be used.

(Image forming device)
Next, a description will be given of a position embodiment of an image forming apparatus provided with a line head composed of the organic EL element of the present invention. FIG. 6 is a schematic configuration diagram illustrating the image forming apparatus 100.

  The image forming apparatus 100 includes a photosensitive drum 116 as an image carrier in the vicinity of the travel path of the transfer medium 122. Around the photosensitive drum 116, an exposure device 115, a developing device 118, and a transfer roller 121 are sequentially disposed along the rotation direction of the photosensitive drum 116 (indicated by an arrow in the drawing). The photosensitive drum 116 is rotatably provided around the rotation shaft 117, and a photosensitive surface 116A is formed on the outer peripheral surface of the photosensitive drum 116 at the central portion in the rotation axis direction. The exposure device 115 and the developing device 118 are arranged in a long axis shape along the rotation axis 117 of the photosensitive drum 116, and the width in the long axis direction substantially coincides with the width of the photosensitive surface 116A.

  In the image forming apparatus 100, first, in the process of rotating the photosensitive drum 116, the surface of the photosensitive drum 116 (photosensitive surface 116 </ b> A) is positive (for example, positive) by a charging device (not shown) provided upstream of the exposure device 115. Then, the surface of the photosensitive drum 116 is exposed by the exposure device 115, and an electrostatic latent image LA is formed on the surface. Further, a toner (developer) 130 is applied to the surface of the photosensitive drum 116 by the developing roller 119 of the developing device 118, and a toner image corresponding to the electrostatic latent image LA is formed by the electric adsorption force of the electrostatic latent image LA. It is formed. The toner particles are positively (+) charged.

  After the toner image is formed by the developing device 118, the toner image comes into contact with the transfer medium 122 by further rotation of the photosensitive drum 116, and the transfer roller 121 has a polarity opposite to the toner particles of the toner image from the back surface of the transfer medium 122. Charge (here, negative (−) charge) is applied, and accordingly, toner particles forming the toner image are attracted from the surface of the photosensitive drum 116 to the transfer medium 122, and the toner image is transferred to the surface of the transfer medium 122. Is transcribed.

  The exposure apparatus 115 includes a line head 110 having a plurality of light emitting elements 200, and an imaging optical element 112 having a plurality of lens elements 113 for imaging the light L emitted from the line head 110 at an erecting equal magnification. ing. The line head 110 and the imaging optical element 112 are held by a head case (not shown) while being aligned with each other, and are fixed on the photosensitive drum 116.

  The line head 110 includes a light-emitting element array 120 in which a plurality of light-emitting elements 200 are arranged along the rotation axis 117 of the photosensitive drum 116, a drive element group including a drive element (not shown) that drives the light-emitting elements 200, And a control circuit group 111 that controls driving of these drive elements (drive element group). The light emitting element 200, the drive element group, and the control circuit group 111 are integrally formed on a long and thin element substrate (base body) 2.

  The imaging optical elements 112 are arranged (arranged) in a staggered manner along the rotation axis 117 of the photosensitive drum 116 with lens elements 113 having the same configuration as a SELFOC (registered trademark) lens element manufactured by Nippon Sheet Glass Co., Ltd. A lens element array 114 is provided.

  In the image forming apparatus 100, the line head 110 includes the organic EL element 1. Therefore, since there is little light emission unevenness, the photosensitive drum can be satisfactorily exposed and a highly reliable image forming apparatus in which no exposure failure occurs.

It is a figure which shows the circuit structure of an organic EL element. It is a top view which shows schematic structure of an organic EL element. It is a figure which shows schematic structure in the cross section of an organic EL element. It is a figure for demonstrating the manufacturing process of an organic EL element. It is explanatory drawing of the process of apply | coating a functional liquid in a pixel area | region from a dispenser. 1 is a diagram illustrating a configuration of an image forming apparatus having a line head of the present invention.

Explanation of symbols

  P ... Substrate, 1 ... Organic electroluminescence element, 40 ... Organic layer (organic functional layer), 40A ... Hole injection layer (organic functional layer), 40B ... Light emitting layer (organic functional layer), 41 ... Pixel electrode (electrode) 50 ... Common bank (bank), 50a ... Opening, 54 ... Cathode (electrode), 71 ... Pixel region, 110 ... Line head, 200 ... Light emitting element

Claims (6)

A light emitting device including an organic functional layer sandwiched between a pair of electrodes on a substrate;
In an organic electroluminescence element comprising: a pixel region in which a plurality of the light emitting elements are arranged; and a bank that partitions the pixel region.
The organic electroluminescence device according to claim 1, wherein the bank is formed such that a width of the pixel region in a short side direction increases from a central portion of the pixel region toward both end sides.   2. The organic electroluminescence device according to claim 1, wherein the substrate has a rectangular shape, and a length in a long side direction is twice or more a length in a short side direction.   3. The organic electroluminescence element according to claim 1, wherein the bank is formed so as to gradually widen a width in a short side direction of the pixel region.   The organic electroluminescent device according to claim 1, wherein the organic functional layer is formed by a liquid phase method.   The organic electroluminescent element according to claim 1, wherein the organic functional layer is formed by laminating various functional layers.   A line head comprising the organic electroluminescence element according to claim 1.

Images