OLED chip, exposure head, image forming apparatus, and method of manufacturing OLED chip

Abstract

Aspects of the present disclosure relate to an OLED chip, an exposure head, an image forming apparatus, and a method of manufacturing an OLED chip. The OLED chip includes: a light emitting region in which a plurality of light emitting devices are two-dimensionally disposed on a surface of a substrate; and a contact region disposed outside the light emitting region. Each of the plurality of light-emitting devices includes a second electrode contiguous on the plurality of light-emitting devices, and the light-emitting region has a long side extending in a first direction and a short side extending in a second direction intersecting the first direction, and an end portion of the second electrode in the first direction has a portion that is not parallel to a third direction perpendicular to the first direction.

Description

Technical Field

[0001] The present disclosure relates to an OLED chip, an exposure head, an image forming device, and a method for manufacturing the OLED chip. Background Art

[0002] The technology described in Japanese Patent Laid-Open No. 2006-236727 is known as a technology related to an exposure head used for an electrophotographic image forming apparatus.

[0003] The exposure head described in Japanese Patent Application Laid-Open No. 2006-236727 includes a substrate on which a plurality of light emitting devices are arranged in the axial direction of a photosensitive drum, and a lens that collects light emitted from the plurality of light emitting devices. In the exposure head, light emitted from the plurality of light emitting devices is collected through the lens to expose the photosensitive drum.

[0004] Therefore, the exposure head described in Japanese Patent Laid-Open No. 2006-236727 is arranged close to the photosensitive drum together with a developing device that develops the latent image formed on the photosensitive drum with a toner. Therefore, the exposure head is arranged close to the developing device. The exposure head includes an organic light emitting diode (OLED) as a light emitting device.

[0005] In the exposure head, ghost spots may appear due to stray light incident on the photosensitive drum. If the ratio of stray light to normal light used for exposure increases, the print quality may deteriorate.

[0006] A known organic light emitting device structure (eg, such as an OLED) includes a light emitting side electrode among a plurality of electrodes arranged with an organic light emitting layer interposed therebetween.

[0007] The configuration described in Japanese Patent Laid-Open No. 2006-236727 includes an organic light-emitting device arranged on a glass substrate and a second electrode arranged on a projection surface of emitted light of the organic light-emitting device, that is, on the opposite side of the photosensitive drum. Summary of the invention

[0008] In known organic light-emitting device structures, the light emitted from the organic light-emitting device may become unexpected stray light due to the scattering of the emitted light. The emitted light may be scattered within the light-emitting substrate of the device, in the housing of the exposure head on which the organic light-emitting device is installed, or on the surface of the photosensitive drum. The stray light thus generated may be reflected by an electrode made of a high-reflectivity metal. Therefore, due to the stray light that has passed through the lens array of the device, ghost spots may appear on the photosensitive drum. In the construction described in Japanese Patent Gazette No. 2006-236727, the second electrode is provided with a stray light reflection prevention unit. In particular, a roughening process is performed on the second electrode of the organic light-emitting device, and an anti-reflection layer is installed between the organic light-emitting layer and the second electrode layer. Therefore, the emission characteristics of the organic light-emitting device itself may be lost.

[0009] One aspect of the present disclosure provides an OLED chip having a reduced ratio of stray light to normal light from a light emitting device without impairing emission characteristics of the light emitting device, and a method of manufacturing the same.

[0010] One aspect of the present disclosure provides an OLED chip, comprising: a light-emitting area (e.g., of the OLED chip), wherein a plurality of light-emitting devices are arranged in a two-dimensional manner on a surface of a substrate (e.g., a main surface of the substrate); and a contact area arranged outside the light-emitting area, wherein each of the plurality of light-emitting devices comprises a first electrode, an organic layer, and a second electrode on a light-emitting side, the second electrode being a common electrode for the plurality of light-emitting devices, and in a plan view of the surface, the light-emitting area has a long side extending in a first direction and a short side extending in a second direction intersecting the first direction, and in a plan view, an end portion of the second electrode along the first direction has a portion that is not parallel to a third direction perpendicular to the first direction.

[0011] Another aspect of the present disclosure provides a method for manufacturing an OLED chip, the method comprising: configuring a vapor deposition mask having a plurality of openings to be opposite to a substrate in which a first electrode and an organic layer are arranged; positioning the substrate relative to the vapor deposition mask; and forming a second electrode by depositing a vapor deposition material on the substrate through the openings of the vapor deposition mask, wherein the openings of the vapor deposition mask have long sides extending along a first direction, short sides extending along a second direction intersecting the first direction, and a portion at an end along the first direction that is not parallel to a third direction perpendicular to the first direction.

[0012] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A is a schematic plan view of an example of a portion of an OLED chip, Figure 1B It is along Figure 1A A cross-sectional view of an OLED chip taken along line IB-IB. Figure 1C yes Figure 1A A magnified view of the IC region of the OLED chip. The IC region is surrounded by dotted lines. Figure 1D It is shown Figure 1A Figure 1 shows an example of the light emitting area of ​​an OLED chip. Figure 1E It is a cross-sectional view taken along line IE-IE of the OLED chip.

[0014] Figure 2 yes Figure 1A An enlarged view of the OLED chip is shown to illustrate the shape of the second electrode.

[0015] Figure 3A and Figure 3B is a schematic plan view of an example of a portion of an OLED chip.

[0016] Figure 4A and Figure 4B is a schematic plan view of an example of a portion of an OLED chip.

[0017] Figure 5A is a schematic plan view of an example of a portion of an OLED chip having a color filter, and Figure 5B It is along Figure 5A A cross-sectional view of an OLED chip taken along line VB-VB.

[0018] Fig. 6A is a schematic plan view of an example of a portion of an OLED chip having a color filter, and Figure 6B It is along Fig. 6A A cross-sectional view of an OLED chip taken along line VIB-VIB.

[0019] Figure 7 is a cross-sectional view showing an example of an exposure head.

[0020] FIG. 8A to FIG. 8E They are schematic diagrams for explaining a head substrate and a lens array in an exposure head, respectively.

[0021] 9A to 9C is a schematic diagram for explaining a method of manufacturing a portion of an OLED chip.

[0022] Fig.10 It is a perspective view of an image forming apparatus.

[0023] Fig.11 yes Fig.10 Schematic cross-sectional view of an image forming apparatus in FIG.

[0024] Fig.12 is a schematic diagram of an example of a portion of an OLED chip. DETAILED DESCRIPTION

[0025] Embodiments for implementing the present disclosure will be described below with reference to the accompanying drawings. Note that unless otherwise specifically described, the sizes, materials, shapes, and relative arrangements of the components described below are not intended to limit the scope of the present disclosure.

[0026] First Exemplary Embodiment

[0027] Will refer to Figures 1A to 4BAn example of an OLED chip of this embodiment is described. The light emitting device 69 in the OLED chip 53 includes a first electrode 63, a second electrode 67, and an organic layer 66 arranged between the first electrode and the second electrode on a substrate 61. A protective layer and a color filter may be provided on the second electrode 67. When a color filter is provided, a planarization layer may be provided between the protective layer and the color filter. The planarization layer may be made of acrylic resin.

[0028] A specific configuration example of an OLED chip will be described with reference to the accompanying drawings. Figure 1A : is a schematic plan view showing an example of a part of an OLED chip 53 using the light-emitting device of the present embodiment. Figure 1B It is along Figure 1A A schematic diagram of a cross section taken along the line IB-IB in FIG. A plan view refers to a plan view along a direction perpendicular to the plane (relative to the normal direction of the plane).

[0029] like Figure 1A As shown, the OLED chip 53 of this embodiment includes: a light-emitting region 60 in which a plurality of light-emitting devices 69 are two-dimensionally arranged on a main surface of a substrate 61 ; and a contact region 64 a disposed outside the light-emitting region 60 .

[0030] like Figure 1B As shown, a plurality of light-emitting devices 69 include: a first electrode 63 arranged on the main surface of a substrate 61; an organic layer 66 arranged on the first electrode 63 and including at least a light-emitting layer; and a second electrode 67 (upper electrode) arranged on the light-emitting side. The second electrode 67 is continuous on the plurality of light-emitting devices 69. In a plan view of the main surface, the light-emitting region 60 has a long side extending along a first direction X and a short side extending along a second direction Y' intersecting the first direction, and an example of a rectangle is shown in this article. In a plan view, the end of the second electrode 67 in the first direction X has a portion that is not parallel to a third direction Y perpendicular to the first direction X. The details will be described below.

[0031] The OLED chip 53 has an insulating layer 62 covering the end of the first electrode 63, the insulating layer 62 having an opening 65 on the first electrode 63 and serving as a bank; and a protective layer 68 arranged on the second electrode 67. In addition, the OLED chip 53 has a wiring 64 arranged on the contact area 64a so as to apply a voltage to the second electrode 67. In addition, the OLED chip 53 has a pad 70 for inputting a control signal from the image forming device body to each OLED chip 53. In the OLED chip 53, a moisture-proof ring 116 is arranged to surround the light-emitting area 60, the contact area 64a, and the pad 70. The moisture-proof ring 116 can suppress moisture from entering the light-emitting device.

[0032] Note that in this specification, the light emitting area 60 of the OLED chip refers to the entire device light emitting area of ​​a plurality of light emitting devices arranged on the substrate of the OLED chip in a plan view. Therefore, when the entire device light emitting area of ​​the plurality of light emitting devices is regarded as one light emitting area, the shape of the light emitting area 60 of the OLED chip is an outer edge shape and may include a non-emitting area such as a bank area.

[0033] Specifically, the outer edge shape of the light emitting region 60 is a region obtained by connecting the ends of the openings 65 of the insulating layer 62 of the plurality of outermost light emitting devices. Figure 1B As shown, in a cross section taken along line IB-IB of the OLED chip, the light emitting region 60 is a region partitioned by a dot-dash line.

[0034] Reference Figure 1C , the outer edge shape of the light emitting area will be described in more detail. Figure 1C Shows Figure 1A 1 is an enlarged view of a region IC of an OLED chip, where the region IC is surrounded by a dot-dash line. Here, among the four light-emitting devices located at the outermost sides along the first direction X, the two light-emitting devices located at the outermost sides along the second direction Y have corners C1 and C2 located at the outermost sides of the openings 65 of the insulating layer 62 of the two light-emitting devices. Similarly, among the four light-emitting devices located at the outermost sides on the opposite side of the first direction X, the two light-emitting devices located at the outermost sides in the second direction Y have corners C3 and C4 located at the outermost sides of the openings 65 of the insulating layer 62 of the two light-emitting devices.

[0035] At this time, if Figure 1D As shown, the shape formed by the line segments connecting the angle C1, the angle C2, the angle C3 and the angle C4 is the outer edge shape of the light emitting area 60. Figures 1A to 1E , the light emitting region 60 is a parallelogram having a long side extending in a first direction X and a short side extending in a second direction Y' intersecting the first direction X. Note that due to the processing accuracy and alignment accuracy in the manufacturing process, the corners C1, C2, C3, and C4 may be rounded. Even in this case, the outer edge shape can be identified by the end of each corner, which is the point where the two line segments forming the corner intersect each other.

[0036] Here, the device light emitting regions of the plurality of light emitting devices may have disconnected portions or gaps along the long sides and short sides of the light emitting region 60; however, as described above, the outer edges of the light emitting regions 60 of the OLED chip are defined by approximate lines of the outer edges of the device light emitting regions. For example, the first direction X and the second direction Y' are directions parallel to the approximate straight lines of the outermost light emitting regions of the device light emitting regions of the plurality of light emitting devices.

[0037] The device light emitting region as the light emitting region of each light emitting device refers to a portion where the first electrode 63, the organic layer 66, and the second electrode 67 are laminated in the opening 65 of the insulating layer 62. The non-light emitting region refers to a region other than the light emitting region.

[0038] In the plan view, the length of the long side of the light emitting region 60 of the present embodiment is greater than or equal to five times the length of the short side. The light emitting region 60 occupies the largest area in the OLED chip 53. Therefore, the length of the long side of the OLED chip 53 is also greater than or equal to five times the length of the short side of the OLED chip 53.

[0039] Configuration and shape of the second electrode

[0040] Reference Figures 1A to 1E , the shape of the second electrode 67 of the OLED chip 53 will be described. In order to reduce stray light in the OLED chip 53, the area of ​​the second electrode 67 that causes unexpected stray light by reflection may be reduced as much as possible. However, the second electrode 67 has a necessary area required for the light emitting device 69 to achieve the initial function. Therefore, without damaging the emission characteristics of the light emitting device 69, the area of ​​the second electrode 67 should be reduced as much as possible.

[0041] In this embodiment, as one aspect, an example will be described in which the contact regions 64a are located at both longitudinal ends of the light emitting region 60, wherein the light emitting devices 69 are arranged two-dimensionally in the longitudinal and transverse directions in the light emitting region 60. However, each contact region 64a may be located anywhere on the substrate 61.

[0042] Since the second electrode 67 is extended to the contact region 64a and deposited, the second electrode area increases when the contact region 64a is arranged away from the light emitting region 60. Therefore, the contact region 64a can be positioned close to the light emitting region 60. From the viewpoint of resistance, the contact region 64a can be positioned close to the light emitting region 60.

[0043] The second electrode of the present embodiment is partially removed at the end portion in the first direction X, and thus the end portion has a portion that is not parallel to the third direction Y. In this way, a portion that is not parallel to the third direction Y is provided (a notch portion is provided), and thus the area of ​​the second electrode can be reduced compared to when the notch portion is not provided.

[0044] This will be described in detail. When the contact region 64a is located outside the light emitting region 60, theoretically, the area of ​​the second electrode 67 can be minimized by depositing the second electrode 67 along the outermost periphery of the light emitting region 60 and the contact region 64a. Figure 1AWhen the structure is formed, the area of ​​the second electrode 67 can be minimized by setting the deposition area of ​​the second electrode 67 to a closed area 71 including multiple light-emitting devices 69 as shown by the double-dotted lines connecting the four corners of the contact area 64a.

[0045] However, for example, when the second electrode 67 is formed through the opening of the vapor deposition mask by vacuum evaporation, a gap is provided between the substrate and the vapor deposition mask where the second electrode is formed by vapor deposition, and the film formed by vapor deposition has a portion blurred by vapor deposition. The portion blurred by vapor deposition has a smaller film thickness, so the resistance tends to be higher, which is disadvantageous. Therefore, the shape of the second electrode 67 needs to correspond to the isotropic margin width (M) of the predetermined alignment accuracy of the vapor deposition device to be used. Therefore, the region 72 including the region 71 shown by the dotted line needs to be the deposition region of the second electrode 67, and the area of ​​the second electrode 67 that helps to reflect unexpected light is larger than the region 71.

[0046] Figure 1E Shown along Figure 1A 1 is a cross-sectional view of an OLED chip taken along line IE-IE. In the substrate 100, a transistor 115 for driving a light-emitting device and an insulator 101 are arranged. On the transistor 115 and the insulator 101, an insulating layer 102, a plug 111 installed in the insulating layer 102, a conductive layer 107, an insulating layer 103, and a plug 112 installed in the insulating layer 103 are arranged in order from the substrate 100.

[0047] Furthermore, on the insulating layer 103, there are arranged in order from the substrate a conductive layer 108, an insulating layer 104, a plug 113 installed in the insulating layer 104, a conductive layer 109, a conductive layer 117 serving as a pad electrode, an insulating layer 105, and a plug 114 installed in the insulating layer 105. A conductive layer 110 serving as a first electrode 63 of the light emitting device is arranged on the insulating layer 105, and an insulating layer 106 is arranged to cover the insulating layer 105, the conductive layer 110, and the conductive layer 117.

[0048] The insulating layer 101 may be, for example, a silicon oxide film such as LOCOS. The insulating layer 102, the insulating layer 103, the insulating layer 104, and the insulating layer 105 may be formed by, for example, a film having at least one of silicon oxide, silicon nitride oxide, silicon nitride oxide, silicon nitride, and aluminum oxide, or by laminating them. Here, the insulating layer 102, the insulating layer 103, the insulating layer 104, and the insulating layer 105 illustrate an example of a silicon oxide film.

[0049] The insulating layer 106 may be a film having low moisture permeability. The insulating layer 106 may be, for example, a silicon nitride film, an aluminum oxide film, or a laminate of these films.

[0050] The conductive layer 107, the conductive layer 108, and the conductive layer 109 may be a layer of a metal such as copper, aluminum, or cobalt, and may also be a laminated layer including a titanium nitride layer, and may be used as wiring, for example. As the conductive layer 110, for example, aluminum, an aluminum alloy, a laminated layer of aluminum or an aluminum alloy and titanium nitride may be used. The first electrode 63 will be described in detail later.

[0051] The moisture-proof ring 116 includes: conductive layers such as plug 111, conductive layer 107, plug 112, conductive layer 108, plug 113, conductive layer 109, plug 114; and insulating layer 106. Surrounding the light-emitting area with the moisture-proof ring 116 including these layers with low moisture permeability can suppress moisture from penetrating into the light-emitting device. The moisture-proof ring is not limited to this, and a part of the conductive layer can be replaced by an insulating layer with low moisture permeability, such as a nitride film, or can be a film partially containing silicon oxide. Even with this configuration, other parts can suppress moisture permeability, so the ring basically serves as a moisture-proof ring.

[0052] Therefore, while the moisture-proof ring 116 of the present embodiment is basically used as a moisture-proof ring, a configuration can be adopted in which a part of the layer does not inhibit the moisture permeability like this.

[0053] Figure 2 8 is an enlarged view of the periphery of the contact region 64a. A circle 80 is an imaginary circle for illustration shown by a dashed line and has a center located at a corner of the contact region 64a, with a radius being a margin width (M) corresponding to the alignment accuracy.

[0054] like Figure 2 As shown, a portion of the second electrode 67 is removed outside the circle 80 (a notch portion 81 is provided), and thus the second electrode 67 has a shape in which its end portion along the first direction X has a portion that is not parallel to the third direction Y. Therefore, compared with when the second electrode 67 is deposited on the region 72 having the long side that is a tangent to the circle 80 and the short side extending in the third direction, the area of ​​the second electrode 67 to be formed can be made smaller.

[0055] By adopting this configuration, even in the case of the largest misalignment, the second electrode 67 can cover the contact region 64a in any region, and the area of ​​the second electrode 67 that contributes to reflection of unintended light can be reduced with sufficient electrical contact. In the present embodiment, an example with a rectangular contact region 64a is shown, and thus the center of the circle 80 is located at a corner of the contact region 64a; however, the center of the circle 80 is not limited thereto.

[0056] Even when the contact region 64a is not a rectangle, it is possible to draw the arc such that the center of the circle 80 moves along the line of the outermost periphery of the contact region 64a by connecting the points farthest from the light emitting region 60. In the region 73 outside the shape thus obtained, the area of ​​the second electrode 67 can be reduced by removing at least a portion of the second electrode 67 (providing the notch portion 81) without impairing the emission characteristics of the light emitting device 69.

[0057] like Figure 3A As shown, this shape can be obtained by cutting off the corner where a line passing through the outermost sides of the light emitting region 60 and the contact region 64a and parallel to the long side of the light emitting region 60 intersects with a line passing through the outermost sides of the light emitting region 60 and the contact region 64a and parallel to the short side of the light emitting region 60. Figure 3B As shown, in Figure 3A In the configuration of , this shape can be obtained by shifting the edge of the second electrode 67 parallel to the third direction Y toward the light emitting region 60 in the first direction, ie, the X direction.

[0058] like Figure 4A As shown, the end of the second electrode 67 in the first direction may be a shape having a curvature. For example, the end of the second electrode 67 in the first direction has a curve, specifically, has a shape in which the curve having the center of curvature in the light emitting region 60 is continuous. Also in this case, the area of ​​the second electrode 67 can be further reduced when the second electrode 67 covers the wiring 64. Figure 4B As shown, only the corners of the second electrode 67 are bent to have a curvature, and a central portion in the third direction Y (a direction perpendicular to the long sides of the light emitting region) may be linear.

[0059] At the end of the second electrode 67 in the first direction, the length of the portion that is not parallel to the third direction Y in the third direction may be longer than the distance L from the end of the second electrode 67 in the third direction to the portion where the second electrode 67 contacts the wiring 64 ( Figure 2 In addition, at the end of the second electrode 67 in the first direction, the length of the portion that is not parallel to the third direction Y in the third direction may be longer than half of the distance L from the end of the second electrode 67 in the third direction to the portion where the second electrode 67 contacts the wiring 64. Figure 2 An example is shown in which the length of the portion non-parallel to the third direction Y in the third direction is approximately equal to the distance L from the end of the second electrode 67 in the third direction to the portion where the second electrode 67 contacts the wiring 64 .

[0060] When film deposition is performed by vacuum evaporation, the shape of the second electrode 67 may vary depending on the distance between the vapor deposition source and the substrate, the taper angle of the opening of the vapor deposition mask in the thickness direction, and whether the OLED chip is deposited near the center of the substrate or at the periphery. However, in a plan view of the main surface of the substrate 61, the end of the second electrode 67 in the first direction X has a portion that is not parallel to the third direction Y perpendicular to the first direction X, so the area of ​​the second electrode 67 can be reduced without impairing the emission characteristics of the light-emitting device 69. Therefore, the reflection of unintended light due to the second electrode 67 can be reduced without impairing the emission characteristics of the light-emitting device 69.

[0061] Since the notch portion is provided, not only the area of ​​the second electrode can be reduced, but also the perimeter of the second electrode can be reduced. It is known that the organic EL device as an example of the light-emitting device of the present embodiment deteriorates due to moisture in the atmosphere. One of the entry points of moisture into the organic EL device is the outer peripheral portion of the second electrode 67. Therefore, reducing the perimeter of the second electrode 67 can suppress the penetration of moisture into the light-emitting device.

[0062] substrate

[0063] The substrate 61 may be made of a material capable of supporting the first electrode 63, the organic layer 66, and the second electrode 67. Figure 1B Although illustration is omitted, active elements such as transistors may be arranged on the substrate 61. In addition, an interlayer insulating layer and / or a wiring layer may be arranged between the substrate 61 and the first electrode 63 as a single layer or multiple layers.

[0064] For example, glass, plastic, or silicon may be used for the substrate 61. In this embodiment, an example using a silicon substrate is shown. The thermal conductivity of a glass substrate is approximately 0.55 to 1.1 W / m·K, while the thermal conductivity of a silicon substrate is approximately 162 W / m·K, so the silicon substrate has extremely high thermal conductivity.

[0065] It is known that an organic light emitting device dissipates heat according to the length of the light emitting time and the magnitude of the light emitting amount. Therefore, the heat generated when the light emitting device 69 is driven is advantageously dissipated efficiently.

[0066] Even when the light emitting device 69 formed on the substrate 61 is driven to generate heat, the use of a silicon substrate as the substrate 61 can efficiently dissipate heat by utilizing heat transfer of the substrate 61. In addition, when the substrate 61 is cooled from the rear surface side by an air cooling mechanism or the like, the light emitting device 69 as a heat source can be efficiently cooled.

[0067] In addition, from the perspective of heat transfer, the thickness of the substrate 61 may be thin. For example, in the case of a silicon substrate, the standard thickness of an 8-inch wafer is 725 μm, but it may be thinned in a back grinding process or the like. However, when a plurality of OLED chips 53 are mounted on another device, a thinner substrate 61 may reduce the yield due to damage such as cracking during handling. To avoid this, the substrate 61 may have a certain degree of thickness.

[0068] For example, the thickness of the substrate 61 may be 200 μm to 700 μm. The thickness of the silicon substrate is more preferably 378 μm to 408 μm. For example, a silicon substrate thinned by a back grinder in the range of 378 μm to 408 μm may be used. Note that switching elements such as transistors, wiring layers, and interlayer insulating layers (not shown) may be arranged on the substrate 61, and the above-mentioned thickness of the silicon substrate refers to the thickness of the structure of the substrate 61 excluding these wiring layers and interlayer insulating layers.

[0069] First electrode

[0070] The first electrode 63 may be transparent or opaque. When the first electrode 63 is opaque, the material used for the first electrode 63 may be a metal material having a reflectivity of 70% or more at the emission wavelength. As the material for the first electrode 63, a metal such as Al or Ag, an alloy obtained by adding Si, Cu, Ni, Nd, etc. to these metals, or ITO, IZO, AZO, IGZO, etc. may be used. For the first electrode 63, for example, a laminated structure of Ti / TiN / AlCu (the sum of the film thickness is 65 nm) may be used.

[0071] Note that the emission wavelength herein refers to the spectral range emitted from the organic layer 66. When the reflectivity of the first electrode 63 is higher than the desired reflectivity, the first electrode 63 may be a laminated electrode using a barrier electrode of a metal such as Ti, W, Mo, Au, or an alloy thereof, or may be a laminated electrode using a transparent oxide film electrode such as an ITO or IZO electrode.

[0072] Meanwhile, when the first electrode 63 is a transparent electrode, a structure in which a reflective layer is further provided under the first electrode 63 may be adopted. As the material of the transparent electrode, for example, ITO, IZO, AZO, IGZO may be used. In order to optimize the optical distance described later, a structure in which an insulating film is further provided between the reflective layer and the transparent conductive film may be adopted.

[0073] Second electrode

[0074] The light emitting device 69 of this embodiment emits light from the second electrode. Therefore, the second electrode 67 is arranged on the organic layer 66 and has a semi-transparent feature. The second electrode 67 can be a semi-transparent conductive layer, which has a feature of transmitting a part of the light reaching the surface and reflecting the other part of the light (for example, a semi-transmissive reflective feature). The material used for the second electrode 67 can have a small work function. For example, alkali metals such as lithium; alkaline earth metals such as calcium; or single metals such as aluminum, titanium, manganese, silver, lead, chromium or mixtures including these metals can be used.

[0075] Alternatively, as the material of the second electrode 67, an alloy of a combination of these single metals may be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver may be used. Among these electrode materials, one type may be used alone, or two or more types may be used. The second electrode may have a single-layer structure or a multilayer structure.

[0076] First, silver can be used, and in order to suppress the aggregation of silver, a silver alloy can be used. If the aggregation of silver can be suppressed, the ratio of the alloy is not limited. For example, the ratio can be 1:1. As a translucent material, an alloy having a main component of magnesium or silver can be used in particular. When the second electrode 67 has a suitable transmittance and reflectivity, a laminated structure with layers of the above materials can be adopted. The second electrode 67 can be shared by a plurality of light-emitting devices 69.

[0077] By using the second electrode 67 made of a semi-transparent material, a device having a top emission structure satisfying the above-mentioned interference condition can be formed. The method of forming the electrode may be a vacuum evaporation method, and is not limited to a specific method, but when a DC or AC sputtering method is used, film coverage is suitable and resistance is easily reduced, which is advantageous.

[0078] For example, the second electrode 67 may have a laminate structure of magnesium and silver (the total film thickness is 15 nm).

[0079] Either the first electrode 63 or the second electrode 67 may be disposed individually for each of the plurality of light emitting devices 69, while the other may be continuous on the plurality of light emitting devices 69. Alternatively, the first electrode 63 and the second electrode 67 may be disposed individually on the plurality of light emitting devices 69.

[0080] In the present exemplary embodiment, an example is shown in which the second electrode 67 is common among the plurality of light emitting devices 69. Therefore, the number of wirings connected from the power supply line to the cathodes 67 of the plurality of light emitting devices 69 can be reduced.

[0081] The second electrode 67 supplies current to the organic layer 66 through the wiring 64, and thus may have a low resistance. When the resistance of the second electrode 67 as a common electrode is high, an increase in the driving voltage of the light-emitting device 69 or uneven brightness due to shadows may occur, and the emission characteristics may be impaired. Therefore, the portion (notch portion 81) removed to reduce the area of ​​the second electrode 67 may be an outer region, rather than an inner region from the contact region 64 toward the light-emitting region 60, which may increase the above-mentioned resistance.

[0082] Organic layer

[0083] The organic layer 66 is disposed on the first electrode 63 and may be formed by a known technique such as a vapor deposition method or a spin coating method.

[0084] The organic layer 66 may have at least a light-emitting layer, and may include a plurality of layers. When the organic layer is an organic compound layer, as the plurality of layers, one or a combination of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer may be mentioned.

[0085] In the light-emitting layer, holes injected from the anode and electrons injected from the cathode are recombined in the organic layer, thereby emitting light. The structure of the light-emitting layer can be a single layer or a multilayer. One of the light-emitting layers can have a red light-emitting material, a green light-emitting material, or a blue light-emitting material, and white light can be obtained by mixing the light-emitting colors.

[0086] Some light emitting layers may include light emitting materials having a complementary color relationship, such as a blue light emitting material and a yellow light emitting material. In either case, light having an emission wavelength according to the application may be emitted, and the emission wavelength may be adjusted by using the light emitting material of the organic light emitting device.

[0087] Alternatively, light of different colors may be emitted by changing the material and configuration included in the light emitting layer of each light emitting device 69. A plurality of light emitting devices 69 may have a common light emitting layer, or each of the light emitting devices 69 may be provided with a light emitting layer. When each of the light emitting devices 69 is individually provided with a light emitting layer, the light emitting layer may be patterned for each light emitting device 69.

[0088] The light emitting device 69 according to the present embodiment may have a first reflective surface, a second reflective surface, and a light emitting layer disposed between the first reflective surface and the second reflective surface. The first reflective surface may be the first electrode 63, or may be a reflective layer disposed between the first electrode 63 and the insulating layer.

[0089] In order to optimize the optical distance between the first reflective surface and the light emitting position of the organic layer 66 including the light emitting layer, let Lr be the optical length from the upper surface of the first reflective surface to the light emitting position of the organic layer 12, and Φr be the phase shift at the reflective layer, then

[0090] Lr=(2m-(Φr / π))×(λ / 4)···(1)

[0091] wherein m is an integer greater than or equal to 0. The film thicknesses of the first electrode 63 or the first reflective surface and the organic layer 66 may be optimized to substantially satisfy the above expression (1).

[0092] The optical distance Ls from the light emitting position to the second reflecting surface substantially satisfies the following expression (2), where Φs is a phase shift when light of wavelength λ is reflected on the reflecting surface. In the present embodiment, m'=0.

[0093] Ls=(2m'-(Φs / π))×(λ / 4)=-(Φs / π)x(λ / 4)···(2)

[0094] Therefore, the full-layer interference L approximately satisfies the following expression (3).

[0095] L=Lr+Ls=(2m-Φ / π)×(λ / 4)···(3)

[0096] Here, Φ is the sum Φr+Φs of phase shifts when light having a wavelength λ is reflected on the first electrode 63 or the reflective layer and the second electrode 67 .

[0097] The above-mentioned “substantially satisfied” means that the permissible range in Expression (1) to Expression (3) is approximately λ / 8 or approximately 20 nm.

[0098] Since the light-emitting position in the light-emitting layer may be difficult to identify, in the above configuration, the light-emitting position is replaced by the interface of the functional layer near the first reflective surface or the interface of the functional layer near the second reflective surface. When the above allowable range is taken into account, even if the light-emitting position is replaced in this way, the effect of enhancing light can be achieved.

[0099] Under the interference condition for enhancing light, it is well known that the distribution of radiated light from a light emitting device is modulated by a Lambertian distribution, so that the forward component increases and the oblique component decreases. Therefore, a light emitting device having a top emission structure that satisfies the interference condition can be used to suppress stray light and improve the resulting print quality.

[0100] For example, on the first electrode 63, a hole injection layer (film thickness of 8nm), a hole transport layer (37nm), a light-emitting layer (20nm), a hole blocking layer (34nm), an electron transport layer (20nm) and an electron injection layer (0.5nm) may be stacked.

[0101] Contact Areas and Pads

[0102] In the contact region 64a, the wiring 64 should ensure electrical contact with the second electrode 67, and can be produced using a metal material such as aluminum (Al), titanium (Ti), and titanium nitride (TiN). In addition, a mixed or laminated structure of these materials can be adopted.

[0103] When the organic layer 66 is deposited by vapor deposition or the like, electrical connection between the second electrode 67 and the wiring 64 should be ensured, so the organic layer 66 may partially cover the wiring 64. The pad 70 needs to be electrically connected to the head substrate 50 by wiring bonding or the like, so it may be produced with the same material as the wiring 64.

[0104] Protective layer

[0105] The protective layer 68 is an insulating layer and has translucency, and may contain an inorganic material having low permeability to oxygen and moisture from the outside. For example, the protective layer 68 may be produced using inorganic materials such as silicon nitride (SiN), silicon oxynitride (SiON), silicon oxide (SiO2), aluminum oxide (Al2O3), and titanium oxide (TiO2).

[0106] In particular, from the perspective of protective performance, inorganic materials SiN, SiON, Al2O3 can be used. In order to form the protective layer 68, a chemical vapor deposition method (CVD method), an atomic layer deposition method (ALD method) or a sputtering method can be used. For example, after forming the second electrode, the device substrate is transferred to another chamber without breaking the vacuum, and a silicon nitride film with a thickness of 2 μm is formed by the CVD method, and the silicon nitride film can be used as a protective layer. After the film is deposited by the CVD method, an atomic layer deposition method (ALD method) can be used to provide a protective layer.

[0107] When the protective layer 68 has sufficient moisture-proof characteristics, the protective layer 68 can have a single-layer structure, or a laminated structure combining the above-mentioned materials and formation techniques. For example, a silicon nitride layer and a high-density layer produced by atomic layer deposition can be laminated. In addition, when the protective layer 68 has sufficient moisture-proof properties, it can have an organic layer. As the organic layer, for example, polyacrylate, polyimide, polyester, epoxy resin can be mentioned. In addition, the protective layer 68 can be arranged on a plurality of light-emitting devices 69.

[0108] For example, after the second electrode 67 is formed, the device substrate is transferred to another chamber while maintaining the vacuum, and a silicon nitride film having a thickness of 2 μm is formed by a CVD method to produce the protective layer 68 .

[0109] An antireflection layer may be provided on the protective layer 68. The antireflection layer is formed so that the optical film thickness (the product of the refractive index and the film thickness) of the film having a refractive index different from that of the protective layer 68 is λ / 4, where λ is a wavelength at which it is desired to suppress reflection. However, compared with a semiconductor laser, the wavelength of light emitted from each light emitting device 69 provides a wide light emission in which the half-value width is generally large.

[0110] Therefore, in order to obtain a sufficient antireflection effect over a wide emission wavelength, a multilayer structure is more advantageous than a single layer structure. The material for the antireflection layer may be magnesium fluoride or silicon oxide, or, as with the planarization layer, may be a polymer. Considering the cost of the manufacturing process associated with film deposition, the use of the color filter described later should be appropriately selected.

[0111] Color Filters

[0112] In this embodiment, an example in which a color filter is not provided on the light-emitting side of the light-emitting device is shown, but a color filter may be provided on the protective layer. For example, a color filter considering the size of the light-emitting device 69 may be provided on another substrate that can be combined with the substrate provided with the light-emitting device, or the color filter may be patterned on the protective layer using photolithography. The color filter may be composed of a polymer. The color filter transmits the desired light from the light-emitting device 69 and absorbs light having unnecessary wavelengths.

[0113] For display device applications, color filters can be provided to enhance the color purity of red, green, and blue light emitting devices. Alternatively, color filters can be provided to separate light from a white light emitting device into red, green, and blue.

[0114] When used for an exposure head of an image forming apparatus, a color filter can be used that transmits light having a wavelength for exposing a photosensitive drum. At the same time, for stray light, the configuration of the color filter needs to be designed. For example, the light-emitting area is not provided with a color filter, but the non-light-emitting area is provided with a color filter that absorbs light from the light-emitting device, so that the stray light can be absorbed without reducing the amount of light incident on the photosensitive drum.

[0115] Alternatively, the light emitting region 60 may be provided with a color filter that transmits light having an emission wavelength, and the non-light emitting region may be provided with a color filter that absorbs light from the light emitting device 69. By adopting this configuration, stray light can be absorbed without reducing the amount of light incident on the photosensitive drum. Note that the color filter provided in the non-light emitting region may be a black resist.

[0116] Planarization layer

[0117] A planarization layer may be provided between the color filter and the protective layer. The planarization layer may be composed of an organic compound, which may be a low molecular weight polymer or a high molecular weight polymer, but may advantageously be a high molecular weight polymer.

[0118] The planarization layer may be disposed above and below the color filter, and the constituent materials thereof may be the same or different. Specifically, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea-formaldehyde resin may be used. Since the planarization layer is also disposed on the color filter, it is possible to reduce the penetration of moisture and oxygen into the color filter from the outside, and the color filter may be protected.

[0119] Second Exemplary Embodiment

[0120] In this embodiment, a configuration example when the OLED chip 53 of the first embodiment has a color filter will be described. Since this embodiment is the same as the first embodiment except that a color filter is provided, the description is omitted. For example, a color filter 91 can be produced by forming a planarization layer 90 on the protective layer 68 to planarize the concavoconvexity of the protective layer 68 due to the light emitting device 69 and then using a photolithography method.

[0121] FIG. 5 shows an example in which a region other than the light emitting region 60 and the pad 70 is provided with a first color filter 91 that absorbs light from the light emitting device 69 . Figure 5A is a plan view of the OLED chip 53, and Figure 5B It is along Figure 5A Schematic diagram of a cross section taken along line VB-VB of FIG. Since the pad 70 needs to establish an electrical connection, a color filter is not arranged on the pad 70.

[0122] On the light emitting device 69, the first color filter 91 is not arranged, but a transparent planarization layer 90 is provided. Therefore, stray light from an unintended direction can be absorbed without reducing the amount of light emitted from the OLED chip 53. The first color filter 91 may be a black resist that also absorbs light other than light having an emission wavelength from the light emitting device 69.

[0123] Fig. 6A and Figure 6B An example is shown in which a region other than the pad 70 is provided with a color filter. Fig. 6A is a plan view of an example of a portion of the OLED chip 53, and Figure 6B It is along Fig. 6ASchematic diagram of a cross section taken along line VIB-VIB of the structure. A second color filter 92 that transmits light having an emission wavelength is provided on the light emitting device 69, and a first color filter 91 that absorbs light from the light emitting device 69 is provided on the light emitting region 60 and the region other than the pad 70. Therefore, stray light from an unintended direction can be absorbed without reducing the amount of normal light emitted by the OLED chip. Note that the first color filter 91 may be a black resist that also absorbs light other than the wavelength corresponding to the light from the light emitting device 69.

[0124] Third Exemplary Embodiment

[0125] Next, refer to Figure 7 The exposure head 4 will be described. Figure 7 2 is a schematic cross-sectional view of the exposure head 4 of the present embodiment. The exposure head 4 of the present embodiment includes the OLED chip 53 of the first embodiment or the second embodiment.

[0126] The exposure head 4 has a long shape (longitudinal shape) extending in the axial direction of the photosensitive drum 2. The exposure head 4 includes a head substrate 50, a light emitting device 69 mounted on the head substrate 50, a lens array 52, and a holding member that holds the head substrate 50 and the lens array 52. ​​The holding member includes a housing 54 described later and a housing support member 55 that supports the housing 54. Herein, the exposure head 4 includes a light emitting diode (OLED) as a light emitting device that emits light, and, for example, an organic light emitting device may be used.

[0127] case

[0128] like Figure 7 As shown, the housing 54 holds the lens array 52 and the substrate 50. In the present embodiment, the housing 54 is a metal member formed by bending a plate material obtained by plating a galvanized steel plate or a cold-rolled steel plate. Here, as an example of an exposure method used by an electrophotographic image forming apparatus, a laser beam scanning exposure method is known, by which an irradiation beam of a semiconductor laser is scanned with a rotating polygonal mirror, and a photosensitive drum is exposed via an f-θ lens. The exposure head 4 described in the present embodiment is arranged adjacent to the photosensitive drum 2, and is used for an OLED exposure method, which exposes the photosensitive drum 2 using a light emitting device 69 arranged in the axial direction of the photosensitive drum 2.

[0129] The housing 54 may be made of metal, for example. For example, the housing 54 is obtained by forming a plate such as a thin sheet made of iron into a character U shape by a press operation. The shape of the housing 54 will be described below.

[0130] The flat portion 54U is opposite to the photosensitive drum 2 in the optical axis direction of the lens of the lens array 52. ​​Note that the flat portion 54U is not limited to a flat surface, and may be a slightly curved surface. The housing 54 has an extension portion 54R extending from one side of the flat portion 54U in the lateral direction in a direction away from the photosensitive drum 2. The housing 54 has an extension portion 54L extending from the other side of the flat portion 54U in the lateral direction in a direction away from the photosensitive drum 2.

[0131] The extension portion 54R and the extension portion 54L form a substrate support member that supports the head substrate 50 inserted through the second opening 54b in the housing 54. The flat portion and the substrate support member (extension portions 54R, 54L) are an integral object and constitute the housing 54 that holds the lens array 52 and the head substrate 50, and the housing 54 is roughly formed in the shape of a character U. Since the housing 54 is roughly formed in the shape of a character U, the second opening 54b is formed on the opposite side of the flat portion 54U. The second opening 54b is formed between the substrate support members (extension portions 54L, 54R) extending from the flat portion 54U to the side away from the photosensitive drum.

[0132] The head substrate 50 is inserted through the second opening 54b, in other words, from the lower side of the U-shaped housing 54, and is bonded to the inner side of each substrate support member (the inner side of the extension portion 54L and the inner side of the extension portion 54R) by an adhesive. The position of the head substrate 50 in the focusing direction is determined by a jig not shown, so the exposure head 4 is not provided with a positioning unit for the head substrate 50 in the focusing direction.

[0133] In addition, the lens array 52 is also bonded to the flat portion 54U by an adhesive, wherein the lens array 52 is inserted into the first opening 54a formed in the flat portion 54U. After adjusting the position and inclination in the focusing direction by a fixture so that the distance in the focusing direction between all OLED chips 53 mounted on the head substrate 50 and the lens array 52 reaches a predetermined value, the lens array 52 is fixed to the flat portion 54U (housing 54). The lens array 52 is fixed to the flat portion 54U at multiple points in the longitudinal direction by an adhesive. In other words, in the longitudinal direction of the flat portion 54U, the exposure head 4 in this example has multiple bonding points, and the lens array 52 inserted into the first opening 54a at these bonding points is bonded and fixed to the flat portion 54U.

[0134] After the head substrate 50 and the lens array 52 are positionally adjusted and fixed relative to the housing 54, the gap between the substrate 50 inserted into the second opening 54b and the housing 54 (extended portions 54L, 54R) is sealed in the longitudinal direction by the sealant 59. Therefore, contamination of the light emitting device 69 by toner and dust from the outside is reduced. Here, the sealant 59 seals only the gap (boundary) between the substrate 50 and the housing 54, and most of the FFC connector 57 and the head substrate 50 are exposed.

[0135] Similarly, the sealant 59 is applied to the gap between the lens array 52 inserted into the first opening 54a and the housing 54 (flat portion 54U), and the gap is sealed in the longitudinal direction by the sealant 59. More specifically, as shown in FIG. Figure 7 As shown, the sealant 59 seals the gap between the side wall of the lens array 52 and the edge of the first opening 54a in the longitudinal direction of the housing 54. Therefore, the possibility of powder dust such as toner entering through the gap between the side wall of the lens array 52 and the first opening 54a and the possibility of the powder dust blocking the light emitted by the light emitting device 69 can be reduced.

[0136] Note that the gap sealed by the sealant 59 is not limited to the gap between the side wall of the lens array 52 on one side and the edge of the first opening 54a, and the sealant 59 also seals the gap between the side wall of the lens array 52 on the other side and the edge of the first opening 54a. The side wall of the lens array 52 on the other side refers to the side wall on the side opposite to the side wall of the lens array 52 on one side. In addition, the gap (e.g., boundary) between the housing 54 and the lens array 52 is sealed by the sealant 59. This reduces the occurrence of contamination of the light emitting device 69 due to toner and dust from the outside.

[0137] As described above, the head substrate 50 and the lens array 52 are held by the housing 54, so that the incident surfaces of the light emitting device 69 and the lens are opposite. Therefore, the light emitted from the light emitting device 69 enters the incident surface of the lens and is emitted from the exit surface of the lens to the photosensitive drum 2 to expose the photosensitive drum 2.

[0138] Here, it is expected that the light emitted from the light emitting device 69 ideally enters the incident surface of all lenses, however, due to the light radiation distribution, some of the light from the light emitting device 69 is emitted obliquely. For example, oblique light that is not directly incident on the lens array from the light emitting device 69 but is incident on the inner wall of the housing of the exposure head and is reflected from the inner wall is light that passes through an unexpected path and may be stray light. In addition, light that normally enters the photosensitive drum 2 from the light emitting device 69 through the lens array 52 may be reflected on the surface of the photosensitive drum 2, or scattered by toner and / or powder and / or dust that may be present in the light path. In addition, Fresnel reflection may occur at the end face of the lens array. When these rays of light pass through the lens array again and are further reflected by the second electrode 67 of the light emitting device 69, the light may become stray light.

[0139] When the light-emitting device 69 is an organic light-emitting device, in the top emission structure, the second electrode with high reflectivity mainly contributes to reflection, which is positioned on the same side as the lens array and closest to the organic layer 66. In order to reduce the above-mentioned stray light, the area of ​​the second electrode can be reduced as much as possible without damaging the emission characteristics of the organic light-emitting device.

[0140] Therefore, in the exposure head 4 of the present embodiment, the area of ​​the second electrode 67 can be reduced by using the OLED chip 53 according to the first embodiment or the second embodiment, compared with when the second electrode has no notch portion, so stray light can be reduced. Since the stray light can be reduced, when the exposure head 4 is used in an image forming apparatus, the number of ghost points due to the stray light can be reduced, and the printing quality can be improved.

[0141] Shell support member

[0142] The housing support member 55 supports the housing 54 in the longitudinal direction and is provided integrally with the housing 54, which holds the head substrate 50 and the lens array 52. ​​The housing support member 55 is a longitudinally shaped member extending in the axial direction of the photosensitive drum 2. Figure 7 As shown, the housing support member 55 is formed in the shape of a character U. The housing support member 55 includes: a left side wall 55L, which serves as a first side wall; a right side wall 55R, which serves as a second side wall opposite to the left side wall 55L; and a bottom surface portion 55D, which is located between the left side wall 55L and the right side wall 55R and is opposite to the flat portion 54U of the housing 54. The bottom surface portion 55D of the housing support member 55 is provided with a plurality of openings 55a in the longitudinal direction, which is the axial direction of the photosensitive drum 2.

[0143] The opening 55a of the housing support member 55 is provided at a position opposed to a surface (a rear surface of the head substrate 50) on the opposite side of a mounting surface (a surface of the head substrate 50) on which the light emitting device 69 of the head substrate 50 is mounted. The opening 55a is provided between the left side wall 55L and the right side wall 55R in a lateral direction perpendicular to the longitudinal direction.

[0144] Substrate and lens array

[0145] Here, we will refer to FIG. 8A to FIG. 8E Description is given of the head substrate 50 and the lens array 52 of the exposure head 4. First, the head substrate 50 will be described. Fig. 8A 2 is a schematic perspective view of the head substrate 50 . Figure 8B 4 shows the configuration of a plurality of light emitting devices 69 provided in the head substrate 50, and Figure 8C Shows Figure 8B Magnified image of .

[0146] The OLED chip 53 is mounted on the head substrate 50. Fig. 8A As shown, one surface of the head substrate 50 is provided with an OLED chip 53, and the other surface is provided with a long flexible flat cable (FFC) connector 57. The one surface of the head substrate 50 referred to here is the surface (e.g., the upper surface or the front surface) on the side provided with the OLED chip 53. The other surface of the substrate is the surface (e.g., the lower surface or the rear surface) on the opposite side to the side provided with the OLED chip 53.

[0147] The FFC connector 57 is mounted on the other surface (lower surface, rear surface) of the head substrate 50 in such a manner that the longitudinal direction of the FFC connector 57 is along the longitudinal direction of the head substrate 50. The long FFC connector 57 is arranged so that a control signal (e.g., a drive signal) is input from a control circuit of the device body of the image forming device, and the control signal is transmitted to each OLED chip 53. The OLED chip 53 is driven (light emission, extinguishing operation) by the control signal input to the head substrate 50.

[0148] The OLED chip 53 mounted on the head substrate 50 will be described. Figure 8B and Figure 8C As shown, a plurality of light emitting devices 69 are arranged on one surface of the head substrate 50. For example, OLED chips 53-1 to 53-29 (29 pieces) are configured. In each of the OLED chips 53-1 to 53-29, a plurality of light emitting devices 69 are arranged in the longitudinal direction, and, for example, 516 light emitting devices 69 are configured.

[0149] In the longitudinal direction of the OLED chip 53, the center-to-center distance k2 of the adjacent light emitting devices 69 corresponds to the resolution of the image forming apparatus 100. For example, when it is assumed that the resolution of the image forming apparatus 100 in this example is 1200 dpi, the light emitting devices 69 are configured so that the center-to-center distance k2 between the adjacent light emitting devices 69 is 21.16 μm in the longitudinal direction of the OLED chips 53-1 to 53-29. Therefore, in this example, the exposure range of the exposure head 4 is approximately 314 mm.

[0150] The photosensitive layer of the photosensitive drum 2 is formed to have a width of 314 mm or more. Since the length of the long side of A4-sized recording paper and the length of the short side of A3-sized recording paper are both 297 mm, the exposure head 4 in this example has an exposure range that allows images to be formed on both A4-sized recording paper and A3-sized recording paper. FIG. 8A to FIG. 8E An example is shown in which the plurality of light emitting devices 69 are arranged in the longitudinal direction, but the light emitting devices 69 may be arranged in the lateral direction in addition to the longitudinal direction.

[0151] The OLED chips 53-1 to 53-29 are arranged along the axial direction of the photosensitive drum 2. Specifically, the OLED chips 53-1 to 53-29 are arranged alternately in two rows in the axial direction of the photosensitive drum 2. Figure 8B As shown, OLED chips 53-1, 53-3, ... 53-29 are installed in a row at odd positions counted from the left in the longitudinal direction of the substrate 50. OLED chips 53-2, 53-4, ... 53-28 are installed in a row at even positions counted from the left in the longitudinal direction of the substrate 50. The OLED chips 53 are configured in this way.

[0152] Therefore, if Figure 8C As shown, in the longitudinal direction of the OLED chip 53, the center-to-center distance k1 between the light-emitting devices 69 arranged at one end of one OLED chip 53 and the other end of another OLED chip 53 in adjacent different OLED chips 53 can be made equal to the center-to-center distance k2 of adjacent light-emitting devices 69 on one OLED chip 53.

[0153] Note that in this embodiment, the light emitting device 69 is an organic light emitting device and a current driven light emitting device. The organic light emitting device is arranged in line along the main scanning direction (axial direction of the photosensitive drum 2) on a thin film transistor (TFT) substrate, for example, and is similarly electrically connected in parallel through a power supply line provided in the main scanning direction.

[0154] Next, the lens array 52 as a lens assembly will be described. Fig.8DThis is a schematic diagram of the lens array 52 as viewed from the photosensitive drum 2 . Fig. 8E is a schematic stereogram of the lens array 52. Fig.8D As shown, the lens array 52 focuses the light emitted from the light emitting device 69 onto the photosensitive drum 2. The lens array 52 is a lens assembly having a plurality of lenses.

[0155] A plurality of these lenses are arranged in two rows in the arrangement direction of the plurality of light emitting devices 69. The lenses are alternately arranged in such a manner that adjacent lenses in one row in the arrangement direction of the lenses are in contact with one of the lenses in the other row. Each lens is a cylindrical rod lens made of glass, and includes: a light incident surface 52b, on which light emitted from the light emitting device 69 is incident; and a light exit surface 52a, from which light entering from the light incident surface is emitted (see Figure 7 ). Note that the material of the lens is not limited to glass, but may be plastic. The shape of the lens is not limited to a cylindrical shape, but may be, for example, a polygonal prism such as a hexagonal prism.

[0156] Fig. 8E The dotted line Z shown in represents the optical axis of the lens. The optical axis of the lens referred to herein means a line connecting the center of the light exit surface of the lens and the focus of the lens. The lens array 52 is a lens assembly having a plurality of lenses, and the above-mentioned "optical axis" is the optical axis of any one of the plurality of lenses. Strictly speaking, the plurality of lenses in the lens array 52 may be slightly tilted toward each other. This is due to tolerance during assembly.

[0157] However, when defining the direction of the optical axis, the deviations approximating the tolerance level described herein are not considered. Therefore, it is assumed that the optical axes of the plurality of lenses are in the same direction. The lens array 52 has the function of focusing the light emitted from the light emitting device 69 onto the surface of the photosensitive drum 2.

[0158] When assembling the exposure head 4, adjust the installation position of the lens array 52 relative to the shell 54 so that the distance between the light-emitting surface of the light-emitting device 69 and the light incident surface of the lens is approximately equal to the distance between the light-emitting surface of the lens and the surface of the photosensitive drum 2.

[0159] like Figure 8BAs shown, in the exposure head 4, a plurality of OLED chips 53 are arranged on the exposure head substrate 50. Thus, since the area of ​​the second electrode 67 in the OLED chip 53 can be reduced, the area contributing to the reflection of unintended light due to the second electrode 67 is reduced in proportion to the number of the OLED chips 53 in the entire exposure head 4. Therefore, half or more of the arranged OLED chips 53 may be the OLED chips 53 according to the first embodiment or the second embodiment, and all of the arranged OLED chips 53 may be the OLED chips 53 according to the first embodiment or the second embodiment.

[0160] This embodiment shows an example of a so-called staggered configuration, in which the OLED chips 53 are arranged alternately in a manner to form two rows. Figure 8C As shown, a region is formed in which the ends of the two OLED chips 53 overlap in the longitudinal direction. This region corresponds to the portion in which the ends of the second electrodes 67 of the OLED chips are located, and thus the reflection area is locally increased in the region of the entire exposure head 4. Therefore, by reducing the area of ​​the second electrode 67 at the ends of the second electrode 67, the reflection area in the overlapping region can be reduced, and thus the stray light caused by the reflection of the unintended light can be efficiently reduced.

[0161] When the OLED chip is used for the exposure head 4, exposure is performed linearly, and thus the shape of the light emitting region 60 has a higher ratio of the length in the longitudinal direction (first direction X) to the length in the transverse direction (second direction Y) than when the OLED chip is used for a display device, etc. In addition, the shape of the substrate of the OLED chip also has a higher ratio of the length in the longitudinal direction (first direction X) to the length in the transverse direction (third direction Y).

[0162] Specifically, for example, the length of the long side of the OLED chip (or the light-emitting region 60) is greater than or equal to 5 times the length of the short side of the OLED chip (or the light-emitting region 60), and may be greater than or equal to 10 times the length of the short side. For example, the length of the long side of the OLED chip (or the light-emitting region 60) may be greater than or equal to 20 times the length of the short side of the OLED chip (or the light-emitting region 60).

[0163] The length of the long side of the OLED chip is determined by the axial length of the photosensitive drum 2, the number of OLED chips arranged in the axial direction, and the configuration of the OLED chip 53. The length of the short side of the OLED chip is determined by whether the light emitting device 69 is arranged on the light emitting area 60 in a direction perpendicular to the axis of the photosensitive drum 2 and the configuration of the pad 70 and the contact area 64a.

[0164] It is known that the organic light emitting device dissipates heat according to the length of the light emitting time and the magnitude of the amount of light emitted. This heat causes thermal expansion of the circuit board in which the organic light emitting device is formed and the head substrate 50 on which a plurality of light emitting devices are mounted, and the deviation of the relative positional relationship between the lens array and the light emitting device 69 may increase the ratio of stray light to normal light.

[0165] When normal light mainly used for exposure is reduced, the ratio of stray light to normal light increases, thereby possibly causing degradation in print quality.

[0166] Thus, in the configuration in which the plurality of OLED chips 53 are mounted on the head substrate 50, even when the light emitting device 69 formed on the substrate 61 is driven to generate heat, the use of a silicon substrate as the substrate 61 enables efficient transmission of heat through the substrate 61 to the head substrate 50. On the other hand, advantageously, when the head substrate 50 is cooled from the rear surface side by the air cooling mechanism, the light emitting device 69 as a heat source can be efficiently cooled.

[0167] Taking into account the wavelength dependency of the exposure sensitivity of the photosensitive drum 2 , the organic layer 66 may be configured to include a light emitting layer that emits red light.

[0168] The OLED chip 53 may have a color filter as shown in the second embodiment. Due to the color filter, stray light from an unintended direction can be absorbed without reducing the amount of normal light incident on the photosensitive drum 2, thereby improving the printing quality.

[0169] Fourth Exemplary Embodiment

[0170] Next, we will refer to 9A to 9C A part of the manufacturing process of the OLED chip 53 is described, but the present disclosure is not limited thereto.

[0171] In the vapor deposition chamber, for example, in the case of the following configuration, the second electrode 67 of the OLED chip 53 in the first embodiment and the second embodiment can be formed on the substrate 61. The method of manufacturing a portion of the OLED chip 53 includes: a process of configuring a vapor deposition mask having a plurality of openings to be opposite to the substrate on which the first electrode and the organic layer are arranged; and a process for positioning the substrate relative to the vapor deposition mask. The method of manufacturing a portion of the OLED chip 53 also includes a process of forming the second electrode by depositing a vapor deposition material on the substrate through the openings of the vapor deposition mask.

[0172] Here, the openings of the vapor deposition mask each have a long side extending in a first direction X, a short side extending in a second direction Y′ intersecting the first direction X, and a portion at an end along the first direction X that is not parallel to a third direction Y intersecting the first direction X.

[0173] First, if Fig. 9A As shown, a substrate 61 held by a substrate holding arm 120 is opposed to a vapor deposition mask 111 arranged on a mask stage 200 and having a plurality of openings. A first electrode 63, an insulating layer 62, and an organic layer 66 are formed on the substrate 61. In addition, wirings 64, pads 70, and circuits for driving light emitting devices 69 may be formed.

[0174] Next, if Fig. 9B As shown, one or both of the substrate 61 and the vapor deposition mask 111 are moved to position the substrate 61 relative to the vapor deposition mask 111. Subsequently, as shown in FIG. Fig. 9C As shown, the second electrode 67 is formed on the substrate 61 by depositing the vapor deposition material 300 on the substrate 61 through the plurality of openings of the vapor deposition mask 111 .

[0175] In the vapor deposition mask 111, the plurality of openings have long sides extending in the first direction X, short sides extending in the second direction Y' intersecting the first direction X, and a portion at an end portion along the first direction X that is not parallel to a third direction Y intersecting the first direction X. Therefore, the second electrode 67 deposited through the openings also has long sides extending in the first direction X, short sides extending in the second direction Y' intersecting the first direction X, and a portion at each end portion along the first direction X that is not parallel to the third direction Y intersecting the first direction X.

[0176] Therefore, the area of ​​the second electrode 67 can be reduced compared to when the second electrode 67 does not have a portion that is not parallel to the third direction Y at the end of the first direction X. Therefore, the influence on the light emission characteristics of the OLED chip 53 due to the reflection of unintended light by the second electrode and the occurrence of stray light in the exposure head 4 having the OLED chip 53 can be reduced. Therefore, when the exposure head 4 of the present embodiment is used for an image forming apparatus, the number of ghost points due to stray light can be reduced, and the printing quality can be improved.

[0177] The manufacturing device for the OLED chip 53 herein is an example, and the present disclosure is not limited thereto. The light emitting device 69 has a plurality of functional layers, and the vapor deposition device as the manufacturing device for the light emitting device 69 includes a large number of vapor deposition chambers corresponding to the plurality of functional layers. In addition to the vapor deposition chamber, the vapor deposition device may also include a plurality of processing chambers such as a preparation chamber, a pretreatment chamber, a transfer chamber, a relay chamber, and a substrate storage chamber.

[0178] Fifth Exemplary Embodiment

[0179] Image forming equipment

[0180] First, refer to Fig.10 and Fig.11A schematic configuration of the image forming apparatus 100 is described. Fig.10 is a perspective view of the image forming apparatus 100 . Fig.11 yes Fig.10 Schematic cross-sectional view of an image forming apparatus in FIG. Fig.10 and Fig.11 The image forming apparatus 100 shown in the embodiment is a copier including a reading device, but the embodiment may also be another image forming apparatus such as a printer that does not include a reading device. In addition, the embodiment is not limited to a color image forming apparatus including a plurality of photosensitive drums 2, and may be a color image forming apparatus including one photosensitive drum or an image forming apparatus that forms a monochrome image.

[0181] Fig.11 The illustrated image forming apparatus 100 includes four image formers 1Y, 1M, 1C, 1K (hereinafter may also be collectively referred to simply as “image formers 1 ”) that form toner images of each color of yellow, magenta, cyan, and black.

[0182] The image formers 1Y, 1M, 1C, and 1K include photosensitive drums 2Y, 2M, 2C, and 2K (hereinafter, they may also be simply collectively referred to as "photosensitive drums 2"), respectively, which are examples of photoreceptors. The photosensitive drums 2 may be photosensitive belts.

[0183] In addition, the image formers 1Y, 1M, 1C, 1K include charging rollers 3Y, 3M, 3C, 3K (hereinafter also simply collectively referred to as "charging rollers 3") as charging units, which are configured to charge the photosensitive drums 2Y, 2M, 2C, 2K, respectively.

[0184] In addition, the image formers 1Y, 1M, 1C, 1K include organic light emitting diode (hereinafter labeled as OLED) exposure heads 4Y, 4M, 4C, 4K (hereinafter also simply referred to as "exposure head 4") as exposure units, which are constructed to expose the photosensitive drums 2Y, 2M, 2C, 2K.

[0185] The image formers 1Y, 1M, 1C, 1K further include developing units 24Y, 24M, 24C, 24K (hereinafter may also be simply collectively referred to as "developing units 24") as developing units, which are configured to develop a toner image of each color on the photosensitive drum 2 by developing the electrostatic latent image on the photosensitive drum 2 with the toner. Note that Y, M, C, K after the symbol represent the color of the toner.

[0186] Fig.11The image forming apparatus 100 shown is an image forming apparatus adopting a so-called "lower surface exposure system" by which the photosensitive drum 2 is exposed from below. A description will be given below assuming that the image forming apparatus adopts the lower surface exposure system. Although not illustrated, as an embodiment, the image forming apparatus may adopt an "upper surface exposure system" by which the photosensitive drum is exposed from above.

[0187] The image forming apparatus 100 includes an intermediate transfer belt 9 to which the toner image formed on the photosensitive drum 2 is transferred, and first transfer rollers 6 (Y, M, C, K) which sequentially transfer the toner image formed on the photosensitive drum 2 to the intermediate transfer belt 9. The intermediate transfer belt 9 is arranged above the image former 1. Note that, instead of an intermediate transfer system using the intermediate transfer belt 9, a direct transfer system may be employed by which the toner image is directly transferred from the photosensitive drum 2 to a sheet.

[0188] In addition, the image forming apparatus 100 includes: a secondary transfer roller 16 as a transfer unit, which is configured to transfer the colorant image on the intermediate transfer belt 9 to the recording paper P transmitted from the feeding unit 11; and a fuser 19 as a fixing unit, which fixes the secondary transferred image to the recording paper P.

[0189] The toner bottles 22Y, 22M, 22C, 22K (hereinafter, may also be simply collectively referred to as "toner bottles 22") storing replenishment toner of each color are units that are attachable to and detachable from the image forming apparatus 100. The toner bottles 22 are arranged above the intermediate transfer belt 9. An appropriate amount of toner is supplied from the corresponding toner bottles 22 to each developing unit included in the four image formers by a toner supply mechanism not shown, as needed.

[0190] The image forming apparatus 100 includes a feeding unit 11 that feeds recording paper P. The feeding unit 11 includes: sheet cassettes 12a, 12b; feeding rollers 13a, 13b; and a resist roller 15. The sheet cassettes 12a, 12b are arranged below the image former 1. The recording paper P stored in the sheet cassettes 12a, 12b is fed one by one by the feeding rollers 13a, 13b, and is conveyed to the second transfer area T2 by the resist roller 15 at a predetermined timing.

[0191] Image formation process

[0192] Next, the image forming process of the image forming apparatus 100 will be briefly described. The charging roller 3Y charges the surface of the photosensitive drum 2Y. The exposure head 4Y exposes the surface of the photosensitive drum 2Y charged by the charging roller 3Y. Thus, an electrostatic latent image is formed on the photosensitive drum 2Y. Next, the developing unit 24Y develops the electrostatic latent image formed on the photosensitive drum 2Y with yellow toner.

[0193] The yellow toner image developed on the surface of the photosensitive drum 2Y is transferred by the first transfer roller 6Y onto the intermediate transfer belt 9. Magenta, cyan, and black toner images are also formed by similar image forming processes and transferred onto the intermediate transfer belt 9 in a superimposed manner.

[0194] The toner image of each color transferred onto the intermediate transfer belt 9 is transported to the secondary transfer area T2 by the intermediate transfer belt 9. The toner image transported to the secondary transfer area T2 is integrally transferred to the recording paper P transported from the feeding unit 11 by the secondary transfer roller 16. The recording paper P to which the toner image is transferred is transported to the fixing device 19. The fixing device 19 fixes the toner image to the recording paper P by applying heat and pressure. The recording paper P that has been fixed by the fixing device 19 is output by the output roller 20 to the output tray 21 arranged above the toner bottle 22. The print quality of the printing on the recording paper P can be evaluated by visual sensory evaluation.

[0195] Sixth Exemplary Embodiment

[0196] In this embodiment, an example of a light emitting device 69 used in the OLED chip according to any one of the first to fifth embodiments will be described.

[0197] Structure of organic light-emitting device

[0198] An organic light emitting device as an example of the light emitting device 69 is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. On the cathode, a protective layer, a color filter, and a microlens may be provided. When a color filter is provided, a planarization layer may be provided between the protective layer and the color filter. The planarization layer may be made of an acrylic resin. The same applies when a planarization layer is provided between the color filter and the microlens.

[0199] substrate

[0200] As the substrate, quartz, glass, silicon wafer, resin and metal can be mentioned. On the substrate, switching elements such as transistors and wiring can be set, and an insulating layer can be set on the substrate. The material for the insulating layer is not limited as long as a contact hole can be formed to enable wiring to the first electrode and insulation from unconnected wiring can be ensured. For example, resins such as polyimide, silicon oxide and silicon nitride can be used. The heat generated by the light emitting device can be efficiently dissipated using a silicon substrate.

[0201] electrode

[0202] A pair of electrodes may be used as electrodes. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting device emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode.

[0203] The material used for the anode may have a work function as large as possible. For example, a single metal such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, or a mixture of these metals, an alloy combining these metals, or a metal oxide such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), or indium zinc oxide may be used. In addition, a conductive polymer such as polyaniline, polypyrrole, or polythiophene may also be used.

[0204] Among these electrode materials, one kind may be used alone or two or more kinds may be used in combination. The anode may be formed of a single layer or a plurality of layers.

[0205] When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum or their alloys or their laminates can be used. With the help of the above materials, the function of a reflective film without an electrode function can be realized. When used as a transparent electrode, a transparent conductive layer of an oxide such as indium tin oxide (ITO) or indium zinc oxide can be used, but is not limited thereto. Photolithography can be used to form the electrode.

[0206] At the same time, the constituent material for the cathode can have a small work function. For example, alkali metals such as lithium, alkaline earth metals such as calcium, or single metals such as aluminum, titanium, manganese, silver, lead or chromium or mixtures thereof can be used. Alternatively, alloys composed of these single metals can be used. For example, magnesium silver, aluminum lithium, aluminum magnesium, silver copper and zinc silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. Among these electrode materials, one type can be used alone, or two or more types can be used in combination. The cathode can have a single-layer structure or a multilayer structure. First, silver can be used, and in order to reduce the aggregation of silver, a silver alloy can be used. If the aggregation of silver can be reduced, the ratio of the alloy is not limited. For example, the ratio of silver to other metals can be 1:1 or 3:1.

[0207] The cathode may be a top-emitting device using an oxide conductive layer such as ITO or silver having a film thickness with a translucent feature, or a bottom-emitting device using a reflective electrode such as aluminum (Al), and is not limited to a specific one. The method of forming the cathode is not limited to a specific one, but when a DC or AC sputtering method is used, the coverage of the film is suitable and the resistance may be reduced, which is advantageous. In either the case of a top-emitting device or a bottom-emitting device, the area of ​​the second electrode can be reduced by making the second electrode having a high reflectivity and serving as a common electrode conform to the shape according to the first embodiment or the second embodiment.

[0208] Pixel separation layer

[0209] The pixel separation layer is composed of a silicon nitride (SiN) film, a silicon oxynitride (SiON) film, or a silicon oxide (SiOx) film produced using a chemical vapor deposition method (CVD method). In order to increase the in-plane resistance of the organic compound layer, the organic compound layer, especially the hole transport layer, can be thinly deposited on the side wall of the pixel separation layer. Specifically, by increasing the cone angle at the side wall of the pixel separation layer and / or the film thickness of the pixel separation layer to increase the occurrence of vignetting during vapor deposition, a film with a smaller thickness can be formed on the side wall.

[0210] At the same time, the side wall taper angle of the pixel separation layer and the film thickness of the pixel separation layer can be adjusted so that no voids are generated in the protective layer formed on the pixel separation layer. Since no voids are generated in the protective layer, the occurrence of defects in the protective layer can be reduced. Since the occurrence of defects in the protective layer is reduced, reliability degradation such as the occurrence of black spots and the occurrence of poor conductivity of the second electrode can be reduced.

[0211] According to this embodiment, even if the taper angle at the side wall of the pixel separation layer is not steep, the charge leakage to the adjacent pixels can be efficiently reduced. The results of the study found that when the taper angle is in the range of 60 to 90 degrees, the charge leakage can be sufficiently reduced. The film thickness of the pixel separation layer is preferably 10nm or more and 150nm or less. Even when the structure includes only pixel electrodes without a pixel separation layer, a similar effect can be obtained. However, in this case, the film thickness of each pixel electrode can be half the thickness of the organic layer or less, or the end of the pixel electrode can have a taper of less than 60° forward, because this can reduce the short circuit of the organic light-emitting device.

[0212] Organic compound layer

[0213] The organic compound layer can be formed as a single layer or multiple layers. When multiple layers are provided, each layer can be referred to as a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer or an electron injection layer according to its function. The organic compound layer mainly includes organic compounds, but may also include inorganic atoms or inorganic compounds. The organic compound layer may contain, for example, copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc. The organic compound layer may be arranged between the first electrode and the second electrode, and may be arranged to contact the first electrode and the second electrode.

[0214] When a plurality of light-emitting layers are provided, a charge generator may be provided between the first light-emitting layer and the second light-emitting layer. The charge generator may include an organic compound whose lowest unoccupied molecular orbital (LUMO) energy is -5.0 eV or less. This also applies when a charge generator is provided between the second light-emitting layer and the third light-emitting layer.

[0215] Protective layer

[0216] A protective layer may be provided on the second electrode. For example, by bonding a glass having a hygroscopic agent to the second electrode, moisture is reduced from entering the organic compound layer, thereby reducing the occurrence of display defects. In another embodiment, moisture may be reduced from entering the organic compound layer by providing a passivation film such as silicon nitride on the cathode. For example, after forming the cathode, the device substrate is transferred to another chamber without breaking the vacuum, a silicon nitride film having a thickness of 2 μm is formed by a CVD method, and the silicon nitride film may be used as a protective layer. After the film is deposited by the CVD method, an atomic layer deposition method (ALD method) may be used to provide a protective layer. The material of the film of the ALD method is not limited, but may be silicon nitride, silicon oxide, aluminum oxide, and the like. On the film formed by the ALD method, silicon nitride may be further formed by the CVD method. The thickness of the film formed by the ALD method may be less than the thickness of the film formed by the CVD method. Specifically, it may be 50% or less, or 10% or less.

[0217] Color Filters

[0218] A color filter may be provided on the protective layer. For example, a color filter considering the size of the organic light-emitting device may be provided on another substrate that may be combined with the substrate provided with the organic light-emitting device, or the color filter may be patterned on the protective layer using photolithography. The color filter may be made of a polymer material.

[0219] Planarization layer

[0220] A planarization layer may be provided between the color filter and the protective layer. The purpose of providing the planarization layer is to reduce the concavity and convexity of the lower layer. The planarization layer may be referred to as a material resin layer without limiting its use. The planarization layer may be composed of an organic compound and may be a low molecular weight polymer or a high molecular weight polymer, but may advantageously be a high molecular weight polymer.

[0221] The planarization layer may be provided above and below the color filter, and their constituent materials may be the same or different. Specifically, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin and urea resin may be mentioned.

[0222] Microlens

[0223] The OLED chip may have an optical component such as a microlens on the light-emitting side. The microlens is made of acrylic resin, epoxy resin, etc. The microlens may have the purpose of controlling the increase in the amount of light extracted from the organic light-emitting device and the direction of the light to be extracted. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents of the hemisphere, there is a tangent parallel to the insulating layer, and the point of intersection between the tangent and the hemisphere gives the vertex of the microlens. The vertex of the microlens can be similarly determined in any cross section. Specifically, among the tangents of the semicircle of the microlens in the cross section, there is a tangent parallel to the insulating layer, and the point of intersection between the tangent and the semicircle gives the vertex of the microlens.

[0224] The midpoint of the microlens may be defined. In the cross section of the microlens, it is assumed that there is a line segment from a point where an arc shape ends to a point where another arc shape ends, and the midpoint of the line segment may be referred to as the midpoint of the microlens. The cross section that determines the vertex and the midpoint may be a cross section perpendicular to the insulating layer.

[0225] The microlens includes a first surface having a convex portion and a second surface opposite to the first surface. The second surface can be arranged closer to the functional layer than the first surface. In order to adopt this configuration, it is necessary to form a microlens on the light-emitting device. When the functional layer is an organic layer, a process in a high temperature state can be avoided during the manufacturing process. When the configuration in which the second surface is arranged closer to the functional layer than the first surface is adopted, all glass transition temperatures of organic compounds included in the organic layer are preferably 100° C. or higher, and more preferably 130° C. or higher.

[0226] Relative substrate

[0227] A relative substrate may be arranged on the planarization layer. It is called a relative substrate because it is arranged at a position opposite to the above-mentioned substrate. The constituent material for the relative substrate may be the same as the constituent material of the above-mentioned substrate. When the above-mentioned substrate is the first substrate, the relative substrate may be the second substrate. If the relative substrate is not required, it may not be arranged.

[0228] Organic layer

[0229] The organic compound layers (such as a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer) included in the organic light emitting device according to an embodiment of the present disclosure are formed by the method shown below.

[0230] A dry process such as vacuum evaporation, ionization vapor deposition, sputtering or plasma can be used for the organic compound layer included in the organic light-emitting device according to the embodiment of the present disclosure. Instead of a dry process, a wet process in which a solute is dissolved in an appropriate solvent can be used, and a layer is formed by a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method).

[0231] When a layer is formed by a vacuum evaporation method or a solution coating method, crystallization is less likely to occur, thereby achieving excellent temporal stability. When a film is deposited by a coating method, the film may be formed in combination with an appropriate binder resin.

[0232] As the above-mentioned binder resin, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin and urea resin may be mentioned, but the binder resin is not limited thereto.

[0233] Among these binder resins, as a homopolymer or a copolymer, one type may be used alone, or two or more types may be mixed and used. In addition, additives such as known plasticizers, antioxidants, or ultraviolet absorbers may be used together as needed.

[0234] Pixel circuit

[0235] The OLED chip may have a pixel circuit connected to the light emitting device. The pixel circuit may be an active matrix type that independently performs light emitting control on the first light emitting device and the second light emitting device. The active matrix circuit may be a voltage programming circuit or a current programming circuit. The driving circuit has a pixel circuit for each pixel. The pixel circuit may include: a light emitting device; a transistor that controls the emission brightness of the light emitting device; a transistor that controls the light emission moment; a capacitor that maintains the gate voltage of the transistor that controls the emission brightness; and a transistor that is not connected to GND via the light emitting device.

[0236] The OLED chip includes a light-emitting area and a peripheral area arranged around the light-emitting area. The light-emitting area has a pixel circuit, and the peripheral area has a display control circuit. The mobility of the transistor included in the pixel circuit may be lower than the mobility of the transistor included in the display control circuit.

[0237] The slope of the current-voltage characteristic of the transistor included in the pixel circuit may be smaller than the slope of the current-voltage characteristic of the transistor included in the display control circuit. The slope of the current-voltage characteristic may be measured using a so-called Vg-Ig characteristic.

[0238] The transistor included in the pixel circuit is a transistor connected to a light emitting device such as the first light emitting device.

[0239] Next, an example of a portion of an OLED chip according to the present embodiment will be described with reference to the drawings.

[0240] Fig.12 1 is a cross-sectional schematic diagram showing an example of an OLED chip having an organic light-emitting device as a light-emitting device and a transistor connected to the organic light-emitting device. The transistor is an example of an active element. The transistor may be a thin film transistor (TFT).

[0241] Fig.12 is an example of a pixel as a constituent element of an OLED chip according to the present embodiment. The pixel has a sub-pixel 10. The sub-pixels are divided into 10R, 10G, and 10B according to their luminescent colors. The luminescent color can be distinguished by the wavelength emitted by the luminescent layer, or the light emitted from the sub-pixel can be selectively transmitted or color-converted by a color filter or the like. In the present embodiment, three types of wavelengths are distinguished by color filters and luminescence; however, when the required wavelength has one type or two types, the corresponding luminescent layer or color filter may each have one or two types. Each sub-pixel includes: a reflective electrode 2, which serves as a first electrode on an interlayer insulating layer 1; an insulating layer 3, which covers the end of the reflective electrode 2; an organic compound layer 4, which covers the first electrode and the insulating layer; a transparent electrode 5; a protective layer 6; and a color filter 7.

[0242] The interlayer insulating layer 1 includes a transistor and a capacitor element in its lower layer or inside. The transistor and the first electrode may be electrically connected via a contact hole not shown.

[0243] The insulating layer 3 is also called a bank or a pixel separation film. The insulating layer 3 covers the end of the first electrode and is arranged to surround the first electrode. The region where the insulating layer is not arranged is in contact with the organic compound layer 4 and serves as a light emitting region.

[0244] The organic compound layer 4 includes a hole injection layer 41 , a hole transport layer 42 , a first light emitting layer 43 , a second light emitting layer 44 , and an electron transport layer 45 .

[0245] Regardless of whether the second electrode 5 is a transparent electrode, a reflective electrode, or a semi-transparent electrode, the second electrode 5 has a material with high light reflectivity and is arranged to be common to a plurality of light emitting devices.

[0246] The protective layer 6 reduces the penetration of moisture into the organic compound layer. The protective layer is shown as a single layer, but may have multiple layers. For each layer, an inorganic compound layer and an organic compound layer may be provided.

[0247] The color filter 7 is divided into 7R, 7G, 7B according to its color. The color filter can be formed on a planarization film not shown. In addition, a resin protective layer (not shown) can be provided on the color filter. The color filter can be formed on the protective layer 6. Alternatively, the color filter can be provided on a relative substrate such as a glass substrate and then combined with the relevant substrate.

[0248] According to one aspect of the present disclosure, an OLED chip having a reduced ratio of stray light to normal light from an organic light emitting device without impairing emission characteristics of the organic light emitting device and a method of manufacturing the same may be provided.

[0249] While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is intended that the scope of the appended claims cover all such modifications and equivalent structures and functions.

Claims

1. An OLED chip, comprising: a light emitting region, wherein a plurality of light emitting devices are arranged in a two-dimensional manner on the surface of the substrate; and a contact region arranged outside the light emitting region, Each of the plurality of light emitting devices comprises a first electrode, an organic layer and a second electrode on a light emitting side, The second electrode is a common electrode for the plurality of light emitting devices. In a plan view of the surface, the light emitting region has a long side extending in a first direction and a short side extending in a second direction intersecting the first direction, and In the plan view, the end portion of the second electrode in the first direction has a portion that is not parallel to a third direction perpendicular to the first direction.

2. The OLED chip according to claim 1, In the plan view, the length of the long side of the light-emitting area is greater than or equal to five times the length of the short side.

3. The OLED chip according to claim 1, In the plan view, the end of the second electrode has a curved line.

4. The OLED chip according to claim 1, In the plan view, a length of a portion not parallel to the third direction along the third direction is longer than 1 / 3 of a distance from an end of the second electrode along the third direction to a portion of the second electrode in contact with a wiring.

5. The OLED chip according to claim 1, wherein a color filter is arranged on the contact area, The color filter includes the contact region in the plan view, and An opening is provided at a position overlapping the light emitting area.

6. The OLED chip according to claim 1, further comprising: a first color filter overlapping the contact region in the plan view; and a second color filter overlapping the light emitting region in the plan view, The color of light transmitted through the second color filter is different from the color of light transmitted through the first color filter.

7. The OLED chip according to claim 6, Wherein, for the light from the plurality of light emitting devices, the transmittance of the first color filter is lower than that of the second color filter.

8. The OLED chip according to claim 1, The substrate is a silicon substrate.

9. The OLED chip according to claim 1, The substrate has a thickness of 200 μm to 700 μm.

10. The OLED chip according to claim 1, The substrate has a thickness of 200 μm to 408 μm.

11. The OLED chip according to claim 1, The substrate has a thickness of 378 μm to 408 μm.

12. An exposure head, comprising: A plurality of OLED chips are arranged on a head substrate, wherein each of the plurality of OLED chips has a side parallel to the longitudinal direction and a side parallel to the transverse direction, and At least one of the plurality of OLED chips is the OLED chip according to claim 1 .

13. The exposure head according to claim 12, Among the plurality of OLED chips, two adjacent OLED chips in the longitudinal direction are arranged in a staggered manner in the transverse direction.

14. An exposure head, comprising: A housing configured to hold: Head substrate; and a lens array arranged at a position opposite to the head substrate, A plurality of OLED chips are arranged on the head substrate. Each of the plurality of OLED chips has a side parallel to the longitudinal direction and a side parallel to the transverse direction, and At least one of the plurality of OLED chips is the OLED chip according to claim 1 .

15. The exposure head according to claim 14, The plurality of OLED chips are arranged such that the second electrode faces the lens array.

16. An image forming device comprising: Photosensitive drum; an exposure head disposed opposite to the photosensitive drum and configured to expose the photosensitive drum to form a latent image on the photosensitive drum; as well as a developing unit configured to develop the latent image formed on the photosensitive drum using toner, The exposure head is an exposure head according to any one of claims 12 to 15.

17. A method for manufacturing an OLED chip, the method comprising: disposing a vapor deposition mask having a plurality of openings to oppose a substrate in which a first electrode and an organic layer are arranged; positioning the substrate relative to the vapor deposition mask; as well as forming a second electrode by depositing a vapor deposition material on the substrate through the opening of the vapor deposition mask, The opening of the vapor deposition mask has a long side extending in a first direction, a short side extending in a second direction intersecting the first direction, and a portion at an end along the first direction that is not parallel to a third direction perpendicular to the first direction.

18. The method for manufacturing an OLED chip according to claim 17, In a plan view of the surface of the substrate, the length of the long side of the light emitting region of the OLED chip to be manufactured is greater than or equal to five times the length of the short side of the light emitting region.

19. The method for manufacturing an OLED chip according to claim 17, Wherein in a plan view of the surface of the substrate, an end portion of the second electrode has a curved line.

20. The method for manufacturing an OLED chip according to any one of claims 17 to 19, In a plan view of the surface of the substrate, a length of a portion not parallel to the third direction along the third direction is longer than 1 / 3 of a distance from an end of the second electrode along the third direction to a portion of the second electrode in contact with a wiring.

Images