JP2007141472A - Electro-optical device, manufacturing method of electro-optical device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical device of which uniformity of emission brightness is improved by avoiding degradation of contrast, and also to provide a manufacturing method the electro-optical device and an image forming device. <P>SOLUTION: Each of a plurality of pixel electrodes 36 with a film thickness of "an electrode thickness D2" is enclosed with an insulating layer with a film thickness of "an insulation layer thickness D1". A common bank 37 commonly enclosing the plurality of pixel electrodes 36 is formed at an outer edge of the insulating layer 35. A difference between "the insulation layer thickness D1" and "the electrode thickness D2" is larger than a film thickness of each of a hole transport layer 41 and a light-emitting layer 42 formed on the pixel electrodes 36. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electro-optical device, a method for manufacturing the electro-optical device, and an image forming apparatus.

  In an electrophotographic printer, an exposure head is used as an electro-optical device that exposes a photosensitive drum to form a latent image. In order to reduce the thickness and weight of the light source of the exposure head, proposals have been made to use organic electroluminescence elements (hereinafter simply referred to as organic EL elements).

  As a method for manufacturing such an exposure head, a so-called ink jet method is known in which a liquid containing a light emitting material is discharged onto a predetermined pixel electrode. In such an ink jet method, since the periphery of the pixel electrode is partitioned by a partition wall, the discharged liquid material can be accommodated on the pixel electrode, thereby enabling high-definition patterning.

  However, in the ink jet method, the evaporation rate of the liquid material discharged onto the pixel electrode depends on the partial pressure of the evaporation component above the pixel electrode. For this reason, there has been a problem that the evaporation rate of the discharged liquid material varies within the plane of the substrate, causing unevenness of the film thickness of the organic EL element, and thus unevenness of the brightness of the exposure head.

Therefore, in the ink jet method, there has conventionally been proposed to eliminate the film thickness unevenness caused by the variation in the evaporation rate (for example, Patent Document 1). In Patent Document 1, a dummy discharge region is provided around the substrate to make the evaporation component above the substrate uniform, thereby improving the uniformity of the evaporation rate within the substrate surface.
JP 2002-222695 A

  By the way, the dry state of the liquid material varies depending on the surface state (lyophilic or lyophobic) of the partition provided around the pixel electrode in addition to the partial pressure of the evaporated component above the pixel electrode. Therefore, even in the case where the dummy discharge region is provided, if the surface state of each partition is not uniform, the dry state of each liquid material varies, and the film thickness uniformity of the light emitting material (light emission luminance) (Uniformity) was insufficient.

  Such a problem is that a large number of partitioned pixel electrodes are surrounded by one partition wall, a liquid material common to the entire region surrounded by the partition walls is discharged, and a light emitting material is stacked on each pixel electrode. This organic EL element can be solved by sharing one partition wall.

  However, when a liquid common to all the pixel electrodes is discharged, a light emitting material is also laminated between the pixel electrodes. As a result, the light emitting material emits light between the pixel electrodes, and there is a problem in that the difference in contrast and contrast (contrast) is reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electro-optical device, a method for manufacturing the electro-optical device, and an image in which uniformity of light emission luminance is improved by avoiding a decrease in contrast. A forming apparatus is provided.

  The electro-optical device of the present invention includes a plurality of light emitting elements having a functional layer formed of a light emitting layer between a first electrode layer and a second electrode layer, and an insulating layer surrounding each of the plurality of first electrode layers. In the electro-optical device including a partition wall that surrounds the plurality of light emitting elements in common, the insulating layer extends from a boundary surface between the first electrode layer and the functional layer to the second electrode layer side. Is equal to or greater than the thickness of each functional layer.

  According to the electro-optical device of the present invention, even when the functional layer is laminated on both the insulating layer and the first electrode layer, the functional layers laminated on the insulating layer are laminated on the first electrode layer, respectively. The corresponding functional layer can be spaced from the corresponding layer. As a result, light emission in a region (on the insulating layer) between the light emitting elements can be avoided, and the functional layer can be stacked on the plurality of first electrode layers including the insulating layer. Therefore, it is possible to improve the film thickness uniformity of the functional layer, that is, the uniformity of the light emission luminance, while avoiding the decrease in contrast.

In this electro-optical device, the insulating layer may have a thickness from the interface between the first electrode layer and the functional layer toward the second electrode layer that is equal to or greater than the thickness of the functional layer. Good.
According to this electro-optical device, even when the functional layer is laminated on both the insulating layer and the first electrode layer, the functional layer laminated on the first electrode layer is replaced with the function laminated on the first electrode layer. It can be spaced from the layer. Therefore, it is possible to reliably avoid a decrease in contrast and improve the uniformity of the light emission luminance.

In this electro-optical device, the insulating layer may have a lyophilic property for lyophilic liquid material for forming the functional layer.
According to this electro-optical device, the thickness uniformity of the functional layer can be improved by the amount that the insulating layer has lyophilicity. Therefore, the uniformity of the light emission luminance can be further improved.

In this electro-optical device, the partition may have a liquid repellency for repelling a liquid for forming the functional layer.
According to this electro-optical device, leakage of the liquid material forming the functional layer can be avoided by the amount that the partition wall has liquid repellency. Therefore, the film thickness uniformity of the functional layer can be further improved.

In this electro-optical device, the functional layer may include at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer.
According to this electro-optical device, the optical characteristics of the light-emitting element can be improved by the amount that the functional layer includes at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer. it can.

In this electro-optical device, the functional layer may be an organic layer.
According to this electro-optical device, since the functional layer can be formed of an organic layer, the material selection range of the functional layer can be expanded, and a constituent material that matches the insulating layer, the first electrode layer, and the like is selected. be able to. As a result, the optical characteristics of the light emitting element can be further improved.

The electro-optical device may include an optical member that condenses light from the light-emitting element.
According to this electro-optical device, the contrast can be improved by the amount of collecting the light from the light emitting element. As a result, the utilization range of light from the light emitting element can be expanded.

In the method of manufacturing the electro-optical device according to the aspect of the invention, a plurality of first electrode layers are formed on the element formation surface of the substrate to form a partition that commonly surrounds the first electrode layer, and the region surrounded by the partition is formed. An electro-optical device in which a liquid layer is ejected to form a functional layer made of a light emitting layer on the plurality of first electrode layers, and a second electrode layer is formed on the functional layer to form a plurality of light emitting elements. In the device manufacturing method, before forming the functional layer, an insulating layer surrounding each of the plurality of first electrode layers is formed, and the first electrode layer and the functional layer are separated from the boundary surface. The thickness of the insulating layer toward the two electrodes was set to be equal to or greater than the thickness of each layer of the functional layer.

  According to the electro-optical device of the invention, each layer of the functional layer laminated on the insulating layer can be separated from each corresponding layer of the functional layer laminated on the first electrode layer. As a result, light emission between the light emitting elements can be avoided and the film thickness uniformity of the functional layer can be improved. Accordingly, it is possible to avoid the decrease in contrast and improve the uniformity of the light emission luminance.

  In this method of manufacturing an electro-optical device, before forming the functional layer, an insulating layer surrounding each of the plurality of first electrode layers is formed, and an interface between the first electrode layer and the functional layer is formed. The thickness of the insulating layer from the first electrode to the second electrode may be equal to or greater than the thickness of each layer of the functional layer.

  According to the method for manufacturing the electro-optical device, the functional layer stacked on the insulating layer can be separated from the functional layer stacked on the first electrode layer. Therefore, it is possible to reliably avoid a decrease in contrast and improve the uniformity of the light emission luminance.

In this method of manufacturing an electro-optical device, the insulating layer may be provided with a lyophilic property for making the liquid material lyophilic.
According to the method for manufacturing the electro-optical device, the thickness uniformity of the functional layer can be improved by the amount that the insulating layer lyophilic liquid. Therefore, the uniformity of the light emission luminance can be further improved.

In this method of manufacturing the electro-optical device, the partition may be provided with liquid repellency for repelling the liquid material.
According to the method for manufacturing the electro-optical device, it is possible to avoid leakage of the liquid material as much as the partition walls repel the liquid material. Therefore, the film thickness uniformity of the functional layer can be further improved.

  In this electro-optical device manufacturing method, the functional layer including at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer is formed on the plurality of first electrode layers. You may do it.

  According to this method of manufacturing an electro-optical device, the optical characteristics of the light-emitting element are increased by forming a functional layer including at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer. Can be improved.

  The image forming apparatus of the present invention includes a charging unit that charges the outer peripheral surface of the image carrier, an exposure unit that exposes the charged outer peripheral surface of the image carrier to form a latent image, and a color for the latent image. In the image forming apparatus including a developing unit that supplies particles and develops a visible image and a transfer unit that transfers the visible image to a transfer medium, the exposure unit includes the electro-optical device described above.

  According to the image forming apparatus of the present invention, it is possible to transfer a desired visible image avoiding a decrease in contrast to a transfer medium.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. First, an electrophotographic printer as an image forming apparatus will be described below.
In FIG. 1, a drive roller 12, a driven roller 13, and a tension roller 14 are provided in a housing 11 of an electrophotographic printer (hereinafter simply referred to as a printer) 10, and each of the rollers 12, 13, 14 is provided. A transfer belt 15 as a transfer medium is stretched. When the driving roller 12 is rotated, the transfer belt 15 is driven to circulate in the direction of the arrow in FIG.

  Above the transfer belt 15, four photosensitive drums 16 as image carriers are provided so as to be rotatable in the direction of the arrow (clockwise) shown in FIG. A photosensitive layer 16S (see FIG. 2) having photoconductivity is formed on the outer peripheral surface of each photosensitive drum 16, and the charge at the irradiated portion is lost by irradiation with light in a predetermined wavelength region. It has come to be.

  A charging roller 17 as a charging unit is rotatably attached to the photosensitive layer 16S of each photosensitive drum 16, and a predetermined charging potential is applied to the entire circumferential surface of the photosensitive drum 16 (the entire photosensitive layer 16S). It is like that.

  On the outer periphery of each photosensitive drum 16 and in the clockwise direction of the charging roller 17 (the rotational direction of the photosensitive drum 16), an exposure head 20 as an electro-optical device constituting an exposure unit is provided. The exposure head 20 is formed in a rectangular parallelepiped shape extending along the axial direction of the photosensitive drum 16, and emits light L in a predetermined wavelength region toward the photosensitive layer 16 </ b> S of the photosensitive drum 16. When the exposure head 20 emits the light L based on the print data, the photosensitive layer 16S is exposed to the light L in a predetermined wavelength region, and the exposed portion of the charge disappears. As a result, an electrostatic image (electrostatic latent image) is formed on the photosensitive layer 16S of the photosensitive drum 16.

  On the outer periphery of the photosensitive drum 16 and in the clockwise direction of the corresponding exposure head 20, a toner cartridge 21 as a developing unit is provided. Each toner cartridge 21 accommodates colored particles (toner) of corresponding colors (black, cyan, magenta, and yellow), and supplies the charged colored particles (toner) to the photosensitive layer 16S of the photosensitive drum 16. It is like that.

  When a bias potential substantially equal to the charging potential is applied to each photosensitive drum 16 and toner is supplied from the corresponding toner cartridge 21, the supplied toner adheres only to the exposed portion of the photosensitive layer 16S. As a result, a single color visible image (developed image) corresponding to the electrostatic latent image is formed (developed) on each photosensitive layer 16S.

  A primary transfer roller 22 is disposed on the outer periphery of the photosensitive drum 16 via the transfer belt 15 in the clockwise direction of the corresponding toner cartridge 21. The primary transfer roller 22 is a conductive roller that induces an electrostatic attraction force by applying a DC voltage, and sucks the toner (developed image) adsorbed on the photosensitive drum 16 so as to perform primary transfer onto the transfer belt 15. It has become. Then, when the toner (developed image) of each color adsorbed on the four photosensitive drums 16 is sequentially primary-transferred onto the transfer belt 15, the image of each color is superimposed on the transfer belt 15 to form a full color image (toner image). To do.

  On the outer periphery of the photosensitive drum 16 and around the corresponding primary transfer roller 22, a cleaning unit 23 including a light source such as an LED and a rubber blade is disposed, and the photosensitive layer 16 </ b> S of the photosensitive drum 16 is neutralized. Thus, the remaining toner is mechanically removed.

A paper feed roller 24 is disposed below the transfer belt 15 to feed the recording paper P to the transfer belt 15 side. A secondary transfer roller 25 that constitutes a transfer unit is disposed on the upper side of the paper feed roller 24 and opposite to the driving roller 12, and electrostatically transfers the toner image formed on the transfer belt 15. And sequentially move (secondary transfer) to the surface of the recording paper P.

  On the upper side of the secondary transfer roller 25, a pair of heat rollers 26 incorporating a heat source and a pair of paper discharge rollers 27 are disposed. The pair of heat rollers 26 is configured to soften the toner secondarily transferred to the recording paper P by heating, and to permeate and solidify the recording paper P. The pair of paper discharge rollers 27 discharges the recording paper from the heat roller 26 to the outside of the housing 11. Then, when the recording paper P on which the toner image is secondarily transferred is supplied to the heat roller 26, the toner image transferred on the surface of the recording paper is fixed, and the recording paper P on which the toner image is fixed becomes the discharge roller 27. Is discharged to the outside of the housing 11.

Next, the exposure head 20 as an electro-optical device provided in the printer 10 will be described below.
In FIG. 2, the exposure head 20 is provided with a case 31 that extends along the axial direction (X arrow direction) of the photosensitive drum 16. The case 31 is formed in a box shape having an opening on the photosensitive drum 16 side. Inside the case 31, a light emitting element array 32 formed so as to extend along the longitudinal direction (X arrow direction) of the case 31 is disposed, and the light L is emitted to the photosensitive drum 16 side (Z arrow direction). It is supposed to be. An optical member 33 fixed to the case 31 is disposed on the photosensitive drum 16 side of the light emitting element array 32, and the light L emitted from the light emitting element array 32 is condensed on the photosensitive drum 16 side to be formed on the photosensitive layer 16S. It comes to lead.

  In FIG. 3, the light emitting element array 32 includes a substrate 34 extending in the direction of the arrow X, and is formed on one side surface (element formation surface 34a) of the substrate 34 so as to cover the entire element formation surface 34a. The insulating layers 35 are laminated.

  The insulating layer 35 is a thin film layer made of an insulator such as a silicon oxide film, and is lyophilic with respect to the liquids Fa and Fb (see FIGS. 8 and 9). In the insulating layer 35, a large number of circular holes 35a penetrating up to the element formation surface 34a are formed. The circular holes 35a are arranged in a staggered pattern along the direction of the arrow X, and a large number of spaces (pixel regions S) surrounded by the insulating layer 35 are defined on the element formation surface 34a.

  In the present embodiment, the thickness of the insulating layer 35 is referred to as “insulating layer thickness D1” (see FIG. 4). The “insulating layer thickness D1” is set based on the film thickness of the pixel electrode 36 as the first electrode and the functional layer 40, and is 220 nm in this embodiment.

  As shown in FIGS. 3 and 4, in each pixel region S, a pixel electrode 36 that uniformly spreads over the entire corresponding element formation surface 34 a is formed. Each pixel electrode 36 is a transparent electrode made of a light transmissive conductive film such as ITO or IZO, and a data signal based on image data is supplied through a corresponding data line (not shown).

In the present embodiment, the film thickness of the pixel electrode 36 is “electrode thickness D2”, which is 50 nm.
On the outer edge of the substrate 34 above the insulating layer 35, a common bank 37 as a partition wall formed in a square frame shape surrounding all the pixel regions S (pixel electrodes 36) is laminated. The common bank 37 is a resin layer having a thickness of about 1 μm formed of a resin material such as an acrylic resin, a polyimide resin, or a fluorine resin, and has a liquid repellency with respect to the liquids Fa and Fb (see FIGS. 8 and 9). It has sex. Then, by forming the common bank 37 on the insulating layer 35, a space (ejection region Sd) surrounding all the pixel regions S (pixel electrodes 36) is partitioned and formed on the substrate 34.

  A functional layer 40 that covers the entire upper surface of the ejection region Sd and over the insulating layer 35 and the pixel electrode 36 is laminated. Note that the functional layer 40 of the present embodiment is a multilayer film including a hole transport layer 41 and a light emitting layer 42 that are sequentially stacked from the substrate 34 side.

  The hole transport layer 41 is an organic layer laminated on the entire upper surface of the pixel electrode 36 and the insulating layer 35 with a uniform film thickness, and is a poly (3,4-ethylenedioxythiophene) as a hole transport layer material. (Hereinafter simply referred to as PEDOT). The hole transport layer 41 is configured to transport holes injected from the pixel electrode 36 to the region of the corresponding light emitting layer 42.

  The hole transport layer 41 is formed by discharging and drying the liquid Fa (see FIG. 8) containing the “PEDOT” over the entire discharge region Sd. That is, the hole transport layers 41 are simultaneously formed by sharing the common bank 37, and the variation in the drying speed of the liquid Fa caused by the common bank 37 is suppressed by the amount of sharing the common bank 37. be able to. As a result, each hole transport layer 41 can improve the uniformity of its film thickness. The hole transport layer material is not limited to this, and a known low molecular weight or high molecular weight hole transport material can be used. When a low molecular weight hole transport layer material is used, The hole transport layer 41 may be formed by a vapor phase process such as a known vapor deposition method.

In the present embodiment, the thickness of the hole transport layer 41 is “first functional layer thickness T1”, which is 50 nm.
The light emitting layer 42 is an organic layer laminated with a uniform film thickness on the entire upper surface of the hole transport layer 41, and is formed of a fluorene-dithiophene copolymer (hereinafter simply referred to as F8T2) as a light emitting layer material. Yes. The light emitting layer 42 recombines holes from the pixel electrode 36 side and electrons from the cathode 43 side, which will be described later, to generate excitons (excitons) by the emitted energy, and the excitons return to the ground state. It emits fluorescence or phosphorescence by emitting energy (emits light).

  The light emitting layer 42 is formed by discharging and drying the liquid Fb (see FIG. 9) containing the “F8T2” over the entire discharge region Sd. That is, the respective light emitting layers 42 are simultaneously formed by sharing the common bank 37, and the variation in the drying speed of the liquid Fb caused by the common bank 37 can be suppressed by the amount of sharing the common bank 37. it can. As a result, each light emitting layer 42 can improve the uniformity of its film thickness. The light emitting layer material is not limited to this, and a known low molecular weight or high molecular weight light emitting material can be used. When a low molecular weight light emitting material is used, a known vapor deposition method or the like can be used. The light emitting layer 42 may be formed by a phase process.

  In the present embodiment, the thickness of the light emitting layer 42 is “second functional layer thickness T2”, which is 120 nm. That is, the “insulating layer thickness D1” is obtained by subtracting the “electrode thickness D2” from the “insulating layer thickness D1” (220−50 = 170 nm), and these “first functional layer thickness T1” and It is set to be “second functional layer thickness T2”, that is, the thickness of each layer of the functional layer 40 or more. Moreover, the “insulating layer thickness D1” is obtained by subtracting the “electrode thickness D2” from the “insulating layer thickness D1”, and the difference between the “first functional layer thickness T1” and the “second functional layer thickness”. It is set to be equal to or greater than the sum of “T2”, that is, the film thickness of the functional layer 40.

  In other words, the insulating layer 35 is set so that the thickness from the upper surface of the pixel electrode 36 (the boundary surface with the functional layer 40) to the upper side is equal to or greater than the film thickness of the functional layer 40. The contact between the functional layer 40 laminated on top and the functional layer 40 laminated on the insulating layer 35 is cut off. Thereby, the insulating layer 35 electrically insulates between the functional layer 40 stacked on the insulating layer 35 and the pixel electrode 36.

  In FIG. 3, on the upper side of the functional layer 40, a cathode 43 as a second electrode layer formed over the entire element formation surface 34a is laminated. The cathode 43 is formed of a conductive material having a low work function (for example, a metal such as LiF, Li, Mg, Ca, or Al), and is supplied with a predetermined common potential common to the pixel regions S. ing. That is, the cathode 43 injects electrons into the light emitting layer 42 of the functional layer 40 formed on each pixel electrode 36. In the present embodiment, the pixel electrode 36, the functional layer 40, and the cathode 43 constitute a light emitting element.

  When a data signal based on image data is supplied to each pixel electrode 36 and a voltage is applied between each pixel electrode 36 and the cathode 43, holes from the pixel electrode 36 pass through the hole transport layer 41. To the light emitting layer 42. At the same time, electrons from the cathode 43 move to the light emitting layer 42, and holes and electrons recombine in the light emitting layer 42, that is, the light emitting layer 42 emits light.

  At this time, each functional layer 40 stacked on the insulating layer 35 is electrically insulated from the pixel electrode 36 by the film thickness “insulating layer thickness D 1” of the insulating layer 35. Therefore, the holes from the pixel electrode 36 and the electrons from the cathode 43 recombine only in the light emitting layer 42 stacked on the pixel electrode 36, that is, only the light emitting layer 42 in the pixel region S emits light.

  Accordingly, the functional layer 40 can be formed in the entire ejection region Sd, and the light emission of the functional layer 40 (light emitting layer 42) located between the pixel regions S (on the insulating layer 35) can be avoided. . As a result, the film thickness uniformity (uniformity of light emission luminance) of the functional layer 40 can be improved, and the decrease in contrast of each pixel region S can be avoided.

Next, a method for manufacturing the exposure head 20 will be described with reference to FIGS.
First, as shown in FIG. 5, an insulating layer 35 having a thickness of “insulating layer thickness D1” (220 nm) is formed on the element forming surface 34a of the substrate 34 by using a known thermal oxidation method, CVD method, or the like. A plurality of circular holes 35a are patterned on the insulating layer 35 by using a known photolithography method. Thereby, a large number of pixel regions S are formed on the element formation surface 34a. At this time, before forming the insulating layer 35, the data lines and various transistors connected to the pixel electrode 36 may be formed in advance on the element formation surface 34a (under the insulating layer 35). Good. Further, after the pixel region S is formed, the insulating layer 35 may be exposed to water vapor or oxygen plasma to enhance the lyophilicity of the insulating layer 35.

  When the pixel region S is formed, as shown in FIG. 6, a liquid material containing ITO or IZO fine particles is discharged only into the pixel region S using a known ink jet method, and the discharged liquid material is dried and dried. Bake. Thus, the pixel electrode 36 having a film thickness of “electrode thickness D2” (50 nm) is formed only in each pixel region S in alignment with each pixel region S.

  When the pixel electrode 36 is formed, as shown in FIG. 7, a known spin coat method or the like is used to apply and form a resin film made of acrylic resin, polyimide resin, or the like on the entire element formation surface 34a. The common bank 37 is patterned by using the photolithography method. Thus, a common bank 37 that commonly surrounds each pixel region S (each pixel electrode 36) is formed, and an ejection region Sd is formed on the element formation surface 34a. At this time, after forming the common bank 37, the surface of the common bank 37 may be exposed to fluorine-based plasma to improve the liquid repellency of the common bank 37.

  When the common bank 37 is formed, as shown in FIG. 8, using the known inkjet method, the liquid Fa in which the “PEDOT” is dissolved in an aqueous solvent is discharged and discharged over the entire discharge region Sd. By drying the liquid Fa, the hole transport layer 41 having a film thickness of “first functional layer thickness T1” is formed.

  At this time, since the liquid Fa is discharged over the entire discharge region Sd, the solvent partial pressure above each pixel region S can be made substantially equal, and the drying speed of the liquid Fa for each pixel region S can be made substantially equal. Can do. Further, the discharged liquid Fa is accommodated in the discharge region Sd without leaking from the discharge region Sd because the common bank 37 has liquid repellency. Further, the discharged liquid Fa can be spread over the entire discharge region Sd because the insulating layer 35 is lyophilic. Accordingly, the hole transport layer 41 having a uniform film thickness of “first functional layer thickness T1” can be formed on both the pixel electrode 36 and the insulating layer 35.

  Moreover, the thickness (220-50 = 170 nm) of the insulating layer 35 from the upper surface of the pixel electrode 36 (the boundary surface with the functional layer 40) to the cathode 43 side is defined as the “first functional layer thickness T1” ( Thicker than 50 nm). Therefore, the hole transport layer 41 stacked on the pixel electrode 36 can be separated from the hole transport layer 41 stacked on the insulating layer 35, and the hole transport layer 41 stacked on the insulating layer 35 is separated from the pixel electrode. 36 can be electrically isolated.

  When the hole transport layer 41 is formed, as shown in FIG. 9, the liquid Fb in which the “F8T2” is dissolved in a nonpolar solvent is discharged over the entire discharge region Sd using a known ink jet method. Then, the discharged liquid material Fb is dried to form the light emitting layer 42 having a film thickness of “second functional layer thickness T2”.

  At this time, since the liquid Fb is discharged to the entire discharge area Sd, the solvent partial pressure above each pixel area S can be made substantially equal, and the drying speed of the liquid Fb for each pixel area S can be made almost equal. Can do. Further, the discharged liquid material Fb is accommodated in the discharge region Sd without leaking from the discharge region Sd because the common bank 37 has liquid repellency. Accordingly, it is possible to form the light emitting layer 42 having a uniform thickness composed of the “second functional layer thickness T2” on each of the pixel electrodes 36 and the insulating layer 35.

  In addition, the thickness (170-50 nm) of the insulating layer 35 from the upper surface of the hole transport layer 41 laminated on the pixel electrode 36 is formed to be equal to or greater than the “second functional layer thickness T2” (120 nm). . Therefore, contact between the light-emitting layer 42 stacked on the pixel electrode 36 and the hole transport layer 41 stacked on the insulating layer 35 can be avoided, and the functional layer 40 stacked on the insulating layer 35 is replaced with a pixel. It can be electrically insulated from the electrode 36.

  When the light emitting layer 42 is formed, a cathode 43 having a predetermined film thickness is formed on the element forming surface 34a using a known vapor deposition method, sputtering method, or the like. Accordingly, it is possible to manufacture the exposure head 20 in which the decrease in contrast of each pixel region S is avoided and the film thickness uniformity (emission luminance uniformity) of the functional layer 40 is improved.

As described above, according to the present embodiment, the following effects are obtained.
(1) According to the present embodiment, each of the plurality of pixel electrodes 36 having a film thickness of “electrode thickness D2” is surrounded by the insulating layer 35 having a film thickness of “insulating layer thickness D1”. . Further, a common bank 37 that surrounds the plurality of pixel electrodes 36 in common is formed on the outer edge of the insulating layer 35. The difference obtained by subtracting the “electrode thickness D2” from the “insulating layer thickness D1” is made larger than the film thicknesses of the hole transport layer 41 and the light emitting layer 42 formed on the pixel electrode 36, respectively. .

Accordingly, even if the liquid materials Fa and Fb are discharged to the entire inside of the common bank 37 and the functional layer 40 is laminated on both the insulating layer 35 and the pixel electrode 36, each layer of the functional layer 40 laminated on the insulating layer 35. The (hole transport layer 41 and the light emitting layer 42) can be separated from the corresponding layers of the functional layer 40 stacked on the pixel electrode 36, respectively. As a result, it is possible to avoid the light emission in the region between the pixel regions S (on the insulating layer 35), and to stack the functional layer 40 on the plurality of pixel electrodes 36 including the insulating layer 35. Therefore, it is possible to avoid the reduction in contrast and improve the film thickness uniformity of the functional layer 40, that is, the uniformity of the light emission luminance.
(2) According to the present embodiment, the difference obtained by subtracting “electrode thickness D2” from “insulating layer thickness D1” is set to be larger than the film thickness of functional layer 40 formed on pixel electrode 36. .

Therefore, the functional layer 40 laminated on the insulating layer 35 can be separated from the functional layer 40 laminated on the pixel electrode 36. As a result, it is possible to reliably avoid light emission in the region between the pixel regions S (on the insulating layer 35).
(3) According to the present embodiment, the insulating layer 35 is given lyophilicity, and the common bank 37 is given liquid repellency. Accordingly, the liquid banks Fa and Fb can be prevented from leaking as much as the common bank 37 has liquid repellency, and can be accommodated in the ejection region Sd. In addition, the liquid Fa can be wetted and spread throughout the discharge region Sd as much as the insulating layer 35 is lyophilic. Accordingly, the hole transport layer 41 and the light emitting layer having a uniform film thickness of “first functional layer thickness T1” and “second functional layer thickness T2” are formed on each pixel electrode 36 and on the insulating layer 35, respectively. Layer 42 can be formed.
(4) According to the present embodiment, the exposure head 20 that improves the uniformity of the light emission luminance while avoiding the decrease in contrast is mounted on the printer 10. Therefore, an image (toner image) having no display unevenness such as brightness unevenness can be formed.
(5) According to this embodiment, the liquid bodies Fa and Fb are discharged to the discharge region Sd to form the hole transport layer 41 and the light emitting layer 42. Therefore, the hole transport layer 41 and the light-emitting layer 42 having a desired film thickness can be formed without using a large-scale vacuum apparatus or a photolithography method having a large number of processes. The light emitting layer 42 can be matched with the shape of the circular hole 35a.

In addition, you may change the said embodiment as follows.
In the above embodiment, the thickness of the insulating layer 35 from the upper surface of the pixel electrode 36 (the boundary surface between the pixel electrode 36) and the cathode 43 is configured to be equal to or greater than the film thickness of the functional layer 40. For example, the thickness of the insulating layer 35 from the upper surface of the pixel electrode 36 (the boundary surface with the functional layer 40) to the cathode 43 side is equal to or greater than the thickness of each layer of the functional layer 40. Good.

According to this, each layer (the hole transport layer 41 and the light emitting layer 42) of the functional layer 40 stacked on the pixel electrode 36 can be separated from the corresponding layer stacked on the insulating layer 35. Therefore, contact between the same layers between the pixel electrode 36 and the insulating layer 35 can be avoided, and light emission between the pixel regions S can be suppressed.
In the above embodiment, after the pixel region S is formed, the pixel electrode 36 aligned with the pixel region S is formed. For example, as shown in FIG. 10, first, each pixel electrode 36 is formed on the element formation surface 34 a, and after forming the insulating layer 35 covering the entire pixel electrode 36, each pixel electrode 36 is formed. A pixel region S corresponding to 36 may be formed.

According to this, it is possible to improve the positional consistency of the pixel region S (functional layer 40) with respect to the pixel electrode 36 only by making the size of the pixel electrode 36 slightly larger than the pixel region S.
In the above embodiment, the pixel electrode 36 is formed in the circular hole 35a, and the function on the pixel electrode 36 is determined by the difference obtained by subtracting the "electrode thickness D2" from the film thickness "insulating layer thickness D1" of the insulating layer 35. Contact between the layer 40 and the functional layer 40 on the insulating layer 35 was avoided. For example, as shown in FIG. 10, the pixel electrode 36 is formed below the circular hole 35 a, and the functional layer on the pixel electrode 36 is changed depending on the film thickness “insulating layer thickness D 1” of the insulating layer 35. You may make it avoid the contact between 40 and the functional layer 40 on the insulating layer 35. FIG.

According to this, when the insulating layer 35 having the same “insulating layer thickness D1” is provided, the film thickness range of the functional layer 40 can be expanded by the “electrode thickness D2”. Further, when the functional layer 40 having the same film thickness is provided, the contact between the functional layer 40 on the pixel electrode 36 and the functional layer 40 on the insulating layer 35 is more reliably ensured by the “electrode thickness D2”. Can be avoided.
In the above embodiment, the functional layer 40 is embodied as the hole transport layer 41 and the light emitting layer 42. For example, the functional layer 40 may be embodied as a laminated film including at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer, and only the light emitting layer 42 is included. It may be embodied in a single layer film made of.
In the above embodiment, the pixel electrode 36 is embodied in a circular shape. For example, the pixel electrode 36 may be embodied in a substantially rectangular shape, and the shape is not limited thereto.
In the above embodiment, the light emitting element is embodied as an organic EL element composed of an organic layer. However, the present invention is not limited thereto, and may be embodied as an inorganic EL element composed of an inorganic layer, for example.
In the above embodiment, the electro-optical device is embodied in the exposure head 20, but is not limited thereto, and may be, for example, an organic electroluminescence display, or an electro-optical device having a light emitting element surrounded by an insulating layer 35. I just need it.

FIG. 3 is an explanatory diagram illustrating an electrophotographic printer according to the present embodiment. Similarly, the schematic perspective view explaining an exposure head. FIG. 2 is a plan view for explaining an exposure head according to the first embodiment. Similarly, a schematic sectional view for explaining an exposure head. Similarly, the explanatory view explaining the manufacturing method of the exposure head. Similarly, the explanatory view explaining the manufacturing method of the exposure head. Similarly, the explanatory view explaining the manufacturing method of the exposure head. Similarly, the explanatory view explaining the manufacturing method of the exposure head. Similarly, the explanatory view explaining the manufacturing method of the exposure head. FIG. 6 is a schematic cross-sectional view illustrating an exposure head of a modification example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Printer as image forming apparatus, 15 ... Transfer belt as transfer medium, 16 ... Photosensitive drum as image carrier, 17 ... Charging roller as charging means, 20 ... Exposure head as electro-optical device, 21 ... Development Toner cartridge as means 33 ... optical member 34 ... substrate 34a ... element forming surface 35 ... insulating layer 36 ... pixel electrode as first electrode layer 37 ... partition wall 40 ... functional layer 41 ... organic layer A hole transport layer constituting 42, a light emitting layer constituting an organic layer, Fa, Fb, a liquid material, and L, light.

Claims (13)

A plurality of light emitting elements having a functional layer made of a light emitting layer between the first electrode layer and the second electrode layer, an insulating layer surrounding each of the plurality of first electrode layers, and the plurality of light emitting elements are shared. An electro-optical device including a partition wall enclosing
The insulating layer has a thickness from the interface between the first electrode layer and the functional layer to the second electrode layer side that is equal to or greater than the thickness of each layer of the functional layer. Optical device. The electro-optical device according to claim 1.
The electro-optical device, wherein the insulating layer has a thickness from the interface between the first electrode layer and the functional layer toward the second electrode layer that is equal to or greater than the thickness of the functional layer. . The electro-optical device according to claim 1 or 2,
The electro-optical device, wherein the insulating layer has a lyophilic property for lyophilic liquid for forming the functional layer. The electro-optical device according to claim 1,
The electro-optical device, wherein the partition wall has a liquid repellency for repelling a liquid material for forming the functional layer. The electro-optical device according to any one of claims 1 to 4,
The electro-optical device, wherein the functional layer includes at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer. The electro-optical device according to any one of claims 1 to 5,
The electro-optical device, wherein the functional layer is an organic layer. The electro-optical device according to any one of claims 1 to 6,
An electro-optical device comprising an optical member for condensing light from the light-emitting element. A plurality of first electrode layers are formed on the element formation surface of the substrate to form a partition that surrounds the plurality of first electrode layers in common, and a liquid is discharged into a region surrounded by the partition to discharge the plurality of the plurality of first electrode layers. In the method of manufacturing an electro-optical device, a functional layer including a light emitting layer is formed on a first electrode layer, and a second electrode layer is formed on the functional layer to form a plurality of light emitting elements.
Before forming the functional layer, an insulating layer surrounding each of the plurality of first electrode layers is formed, and the interface from the interface between the first electrode layer and the functional layer to the second electrode side is formed. A method of manufacturing an electro-optical device, wherein the thickness of the insulating layer is equal to or greater than the thickness of each of the functional layers. The method of manufacturing an electro-optical device according to claim 8.
Before forming the functional layer, an insulating layer surrounding each of the plurality of first electrode layers is formed, and the interface from the interface between the first electrode layer and the functional layer to the second electrode side is formed. The method of manufacturing an electro-optical device, wherein the thickness of the insulating layer is equal to or greater than the thickness of the functional layer. The method of manufacturing an electro-optical device according to claim 8 or 9,
A method for manufacturing an electro-optical device, wherein the insulating layer is provided with a lyophilic property for lyophilicizing the liquid material. In the manufacturing method of the electro-optical device according to any one of claims 8 to 10,
A method for manufacturing an electro-optical device, wherein the partition wall is provided with liquid repellency for repelling the liquid material. In the manufacturing method of the electro-optical device according to any one of claims 8 to 11,
The functional layer including at least one of a hole transport layer, an electron transport layer, a hole barrier layer, and an electron barrier layer is formed on the plurality of first electrode layers. Manufacturing method of optical device. A charging means for charging the outer peripheral surface of the image carrier, an exposure means for exposing the outer peripheral surface of the charged image carrier to form a latent image, and supplying colored particles to the latent image to form a visible image. In an image forming apparatus comprising: a developing unit that develops; and a transfer unit that transfers the visible image to a transfer medium.
An image forming apparatus comprising the electro-optical device according to claim 1.

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