JP7797574B2 - Light-emitting device, manufacturing method thereof, and image-forming device - Google Patents

Description

The present invention relates to a light-emitting device, a manufacturing method thereof, and an image forming device.

There are light-emitting devices in which multiple functional layers, such as a hole injection layer, hole transport layer, light-emitting layer, electron transport layer, and electron injection layer, are formed in a vapor deposition process using a vapor deposition mask. The vapor deposition mask has multiple openings, and in the vapor deposition process, materials for the functional layers can be vapor-deposited onto a substrate through the multiple openings. Meanwhile, a moisture-resistant ring can be provided in the light-emitting device to prevent moisture from penetrating into a light-emitting element having multiple functional layers. Patent Document 1 describes a light-emitting device with a rectangular guard ring.

Japanese Patent Application Laid-Open No. 2018-29070

The deposition mask may have protrusions called ribs or the like to maintain a constant gap between the pattern portion of the deposition mask and the material substrate. During the deposition process, the deposition mask may be positioned so that the protrusions come into contact with the contact-permitted area of the material substrate (the area where contact with the protrusions is permitted). If the contact-permitted area is located outside the moisture-resistant ring, adjacent light-emitting devices on the material substrate will be separated by the contact-permitted area, which limits the number of light-emitting devices that can be obtained from a single substrate. This can increase the manufacturing costs of the light-emitting devices.

The present invention aims to provide an advantageous technology for reducing the manufacturing costs of light-emitting devices with moisture-resistant ring structures.

One aspect of the present invention relates to a light-emitting device having a substrate having first and second sides parallel to a first direction and third and fourth sides parallel to a second direction perpendicular to the first direction, the light-emitting device comprising: a light-emitting element array having a plurality of light-emitting elements arranged on the substrate ; a pad arranged on the substrate so as to be positioned between the first side and the light-emitting element array; and a moisture-resistant ring structure arranged on the substrate so as to prevent moisture from penetrating into the light-emitting element array and the pad, the moisture-resistant ring structure including a moisture-resistant wall arranged between the light-emitting element array and the first side, and the shortest distance between the light-emitting element array and the moisture-resistant wall in the second direction is smaller than the distance between the light-emitting element array and the moisture-resistant wall on an imaginary line parallel to the second direction and passing through the light-emitting element array and the pad.

The present invention provides an advantageous technology for reducing the manufacturing costs of light-emitting devices with moisture-resistant ring structures.

FIG. 1 is a plan view schematically showing a plurality of light emitting devices in the process of being manufactured, arranged on a material substrate. FIG. 1 is a plan view illustrating an example of a deposition mask. FIG. 3 is an enlarged plan view of a portion of the deposition mask of FIG. 2 . FIG. 2 is a cross-sectional view schematically showing a material substrate and a deposition mask arranged on top of each other. FIG. 10 is a plan view illustrating another deposition mask. FIG. 1 is a plan view schematically showing the configuration of a light emitting device according to a first embodiment. FIG. 7 is a cross-sectional view schematically showing the B-B' cross section of FIG. 6; A cross-sectional view schematically showing the C-C' cross section of Figure 6. FIG. 10 is a plan view schematically showing the configuration of a light emitting device of a comparative example. FIG. 10 is a plan view schematically showing the configuration of a light emitting device according to a second embodiment. FIG. 10 is a plan view schematically showing the configuration of a light emitting device according to a third embodiment. FIG. 1 is a diagram schematically illustrating a configuration of an image forming apparatus according to an embodiment. FIG. 10 is a diagram illustrating an example of an arrangement of a plurality of light emitting devices. 10A to 10C are diagrams for explaining modified examples of the light emitting devices according to the first to third embodiments. A cross-sectional view schematically showing the D-D' cross section of Figure 6. 10 shows the arrangement of substrates and deposition masks in the light-emitting device of the fourth embodiment. FIG. 10 is a cross-sectional view of an example of a light emitting device according to a fourth embodiment. FIG. 10 is a plan view of an example of a light emitting device according to a fourth embodiment. 19 is a cross-sectional view of an example taken along the E-E' plane in FIG. 18. FIG. 13 is a plan view of an example of a light emitting device according to a fifth embodiment. FIG. 13 is a plan view of an example of a light emitting device according to a sixth embodiment. A cross-sectional view of an example taken along the F-F' plane in Figure 21.

The following describes the embodiments in detail with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claimed invention. While the embodiments describe multiple features, not all of these features are necessarily essential to the invention, and multiple features may be combined in any desired manner. Furthermore, in the attached drawings, the same reference numbers are used to designate identical or similar components, and redundant explanations will be omitted.

The structure of the light-emitting device 2 of the first embodiment and a method for manufacturing it are described below as examples. The numerical values, shapes, materials, components, component arrangements, and connection configurations described herein do not limit the scope of the disclosure unless explicitly stated otherwise. The light-emitting device 2 can be manufactured by processing a material substrate such as a silicon wafer. To avoid complication, this specification may also refer to a light-emitting device in the process of being manufactured. Furthermore, directions are described in this specification and drawings according to the XYZ coordinate system. Here, the XYZ coordinate system is defined so that the principal surface of the material substrate or light-emitting device is parallel to the XY plane. For ease of explanation, the X direction is described as the first direction and the Y direction as the second direction perpendicular to the first direction. However, for example, the Y direction may be described as the first direction and the X direction as the second direction. In the following description, a plan view is synonymous with a planar view and also with an orthogonal projection onto the XY plane.

Figure 1 schematically shows multiple light-emitting devices 2 in the process of being manufactured, arranged on a material substrate 1 such as a silicon wafer. Each light-emitting device 2 is provided with a light-emitting element array 3, or a light-emitting element array 3 is defined. A defined light-emitting element array 3 means that the area where the light-emitting element array 3 is planned to be formed has been defined, but the light-emitting element array 3 is not yet complete. A completed light-emitting element array 3 has multiple light-emitting elements. The light-emitting element array 3 or the multiple light-emitting elements may include multiple first electrodes that can be individually controlled, an organic film disposed on the multiple first electrodes, and a second electrode disposed on the organic film. In one example, the organic film and the second electrode may be shared by multiple light-emitting elements. The organic film may be composed of multiple functional layers. Each of the multiple functional layers may be composed of an organic material. In another aspect, each of the multiple light-emitting elements may include a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, and an electron injection layer.

Figure 2 schematically shows a vapor deposition mask 4 for manufacturing multiple light-emitting devices 2. The dotted lines or circles in Figure 2 indicate the areas where the material substrate 1 is disposed. Figure 3 is an enlarged view of a portion of Figure 2. The vapor deposition mask 4 shown in Figures 2 and 3 can be used to form multiple organic films by vapor deposition on the light-emitting element array 3 of each light-emitting device 2. Figure 4 schematically shows the material substrate 1 and vapor deposition mask 4 stacked on top of each other. Figure 4 corresponds to the A-A' cross section of Figure 2. The vapor deposition mask 4 has a pattern portion PP with multiple rectangular regions RR corresponding to the multiple light-emitting devices 2, and multiple protrusions 6. Each rectangular substrate region RR can have one opening 5 for forming an organic film. Each rectangular substrate region RR may also have multiple openings 5. During the vapor deposition process, material gas emitted from a material gas supply source can pass through each opening 5 and be supplied to the material substrate 1.

The material substrate 1, or multiple light-emitting devices 2 in the process of being manufactured, has a contact-permitting region 10, which is an area that is permitted to come into contact with the protrusion 6 of the deposition mask 4. The contact-permitting region 10 may typically be a part of the upper surface of a layer stacked on the material substrate 1, but for simplicity, such an area will also be expressed here as the contact-permitting region 10 of the material substrate 1. Each light-emitting device 2 in the process of being manufactured may have at least one contact-permitting region 10, and preferably at least two contact-permitting regions 10.

The deposition mask 4 does not contact the material substrate 1 (and the layers laminated on the material substrate 1) except when the protrusions 6 contact the corresponding contact-permitting regions 10. The gap between the material substrate 1 and the pattern portion PP of the deposition mask 4 is defined by contacting the protrusions 6 of the deposition mask 4 with the contact-permitting regions 10 of the material substrate 1. This method is advantageous for arranging the material substrate 1 and the pattern portion PP of the deposition mask 4 in close proximity while maintaining an accurate gap between them. This is useful for suppressing deposition in unnecessary regions and for miniaturizing individual light-emitting devices 2. Traces of contact by the protrusions 6, which are part of the deposition mask 4, may be left on the contact-permitting regions 10 during the manufacturing process of the light-emitting device 2. Such traces may be scratches, for example.

A magnet can be used to secure the deposition mask 4 to the material substrate 1. In this case, the deposition mask 4 can be made of a magnetic material such as invar. Alternatively, a pressure mechanism that presses the deposition mask 4 against the material substrate 1 can be used to secure the deposition mask 4 to the material substrate 1.

After an organic film (multiple functional layers) is formed on the light-emitting element array 3 using the vapor deposition mask 4 shown in Figures 2 and 3, a second electrode can be formed using the vapor deposition mask 4 schematically shown in Figure 5. The dotted lines or circles in Figure 5 indicate the area where the material substrate 1 is located. The vapor deposition mask 4 has a pattern portion PP with multiple rectangular substrate regions RR corresponding to the multiple light-emitting devices 2, and multiple protrusions 6, and each rectangular substrate region RR can have one opening 5 for forming a second electrode. After the multiple second electrodes are formed, a protective film can be formed over the entire material substrate 1 to cover the multiple second electrodes on the material substrate 1. This can prevent moisture from penetrating the organic film (multiple functional layers).

Figure 6 shows a schematic diagram of one light-emitting device 2. The light-emitting device 2 has a rectangular substrate RS with a first side S1 and a second side S2 parallel to the X direction (first direction) and a third side S3 and a fourth side S4 parallel to the Y direction (second direction) perpendicular to the X direction (first direction). The rectangular substrate RS is a portion of the material substrate 1, more specifically, a portion that has been diced into chips from the material substrate 1. The light-emitting device 2 may also include a light-emitting element array 3 composed of multiple light-emitting elements arranged on the rectangular substrate RS, and one or more pads 8 arranged on the rectangular substrate RS so as to be located between the first side S1 and the light-emitting element array 3. The light-emitting device 2 may also include a moisture-resistant ring structure 70 arranged on the rectangular substrate RS to prevent moisture from penetrating into the light-emitting element array 3 and all pads 8. The pads may be connected to an external circuit.

The moisture-resistant ring structure 70 may include a moisture-resistant wall 71 disposed between the light-emitting element array 3 and the first edge S1. In FIG. 6 , the moisture-resistant wall 71 in the moisture-resistant ring structure 70 is indicated by a bold gray line. The shortest distance between the light-emitting element array 3 and the moisture-resistant wall 71 in the Y direction (second direction) is distance d1. The distance between the light-emitting element array 3 and the moisture-resistant wall 71 on an imaginary line VSL parallel to the Y direction (second direction) and passing through the light-emitting element array 3 and the pad 8 is distance d2. In the first embodiment, distance d1 is smaller than distance d2. This is advantageous for reducing the distance (spacing) between adjacent light-emitting devices 2 in the Y direction on the material substrate 1, thereby increasing the number of light-emitting devices 2 that can be formed on the material substrate 1 and reducing the manufacturing costs of the light-emitting devices 2.

The moisture-resistant ring structure 70 may include a first moisture-resistant ring 7 arranged to surround the light-emitting element array 3 and the pad 8. The moisture-resistant wall 71 may be part of the first moisture-resistant ring 7. The first moisture-resistant ring 7 may be arranged to surround the entire periphery of the light-emitting element array 3.

The light-emitting device 2 may further include a plurality of contact regions 9 arranged on the rectangular substrate RS to receive signals or potentials for driving the plurality of light-emitting elements of the light-emitting element array 3. The plurality of contact regions 9 may be electrically connected to second electrodes of the plurality of light-emitting elements. The moisture-resistant ring structure 70 may be arranged on the rectangular substrate RS to prevent moisture from penetrating into the light-emitting element array 3, the plurality of pads 8, and the plurality of contact regions 9. More specifically, the first moisture-resistant ring 7 of the moisture-resistant ring structure 70 may be arranged on the rectangular substrate RS to surround the light-emitting element array 3, the plurality of pads 8, and the plurality of contact regions 9. The first moisture-resistant ring 7 may preferably be arranged on the rectangular substrate RS to surround the entire periphery of the light-emitting element array 3, the plurality of pads 8, and the plurality of contact regions 9.

It is preferable that the dimension in the X direction (first direction) of the smallest rectangle (virtual minimum rectangle) circumscribing the light-emitting element array 3 is greater than the dimension in the Y direction (second direction). For example, the dimension in the X direction (first direction) of the smallest rectangle (virtual minimum rectangle) circumscribing the light-emitting element array 3 can be two or more times, three or more times, or five or more times the dimension in the Y direction (second direction).

The multiple contact regions 9 may include a first contact region 9a, a second contact region 9b, and a third contact region 9c. The first contact region 9a is disposed between the light-emitting element array 3 and the first side S1, the second contact region 9b is disposed between the light-emitting element array 3 and the third side S3, and the third contact region 9c is disposed between the light-emitting element array 3 and the fourth side S4. In FIG. 6, the multiple contact regions 9 are labeled 9a, 9b, and 9c to distinguish them from one another. In FIG. 6, the multiple pads 8 are labeled 8a, 8b, 8c, and 8d to distinguish them from one another. In one example, the portion of the moisture-resistant wall 71 that defines the shortest distance d1 may be disposed between the first pad 8b and the first contact region 9a on the imaginary line VSL. The multiple pads 8 may include a first pad 8b on the virtual straight line VSL as well as a second pad 8c arranged on the rectangular substrate RS so as to be located between the first side S1 and the light-emitting element array 3. The portion of the moisture-resistant wall 71 that defines the shortest distance d1 may be located between the first pad 8b and the second pad 8c.

Figure 7 schematically shows the B-B' cross section of Figure 6. However, in Figure 7, components arranged below the first electrode 13 of the light-emitting element 19 that constitutes the light-emitting element array 3 are omitted. The light-emitting element 19 may include the first electrode 13, an organic film 14 arranged on the first electrode 13, and a second electrode 15 arranged on the organic film 14. The organic film 14 may include multiple functional layers. The first electrode 13 may be an independent electrode provided for each light-emitting element 19, and the second electrode 15 may be a common electrode provided in common to multiple light-emitting elements 19.

Light generated by the light-emitting elements 19 passes through the second electrode 15 before being emitted from the light-emitting device 2, so the second electrode 15 is composed of a transparent or translucent layer. The second electrode 15 is composed of, for example, a thin film of a metal material, and therefore can have a relatively high wiring resistance. If the light-emitting element array 3 is elongated in the X direction and the contact regions 9 are arranged only in the longitudinal direction of the light-emitting element array 3, a voltage drop in the second electrode 15 will cause shading, in which the brightness changes with increasing distance from the contact region 9. To address this issue, as exemplified by contact region 9a in Figure 6, a number of contact regions 9 corresponding to the longitudinal length of the light-emitting element array 3 can be arranged at appropriate locations in the longitudinal direction.

Figure 8 shows a schematic cross section taken along line C-C' in Figure 6. The first moisture-resistant ring 7 can be formed, for example, by laminating contact plugs and metal wiring. The surface of the first moisture-resistant ring 7 is covered with a protective film 16, which prevents moisture from penetrating from the outside of the first moisture-resistant ring 7 to the inner region (including the light-emitting element array 3).

Figure 15 schematically shows the D-D' cross section of Figure 6. Figure 15 also shows an example of a light-emitting element 23 and a transistor 20 connected to the light-emitting element 23. The transistor 20 is an example of an active element. The transistor 20 may be a thin-film transistor (TFT).

The drain 25 and source 24 of the transistor 20 are arranged on the material substrate 1, and the gate 26 of the transistor 20 is arranged on the material substrate 1 via a gate insulating film (not shown).

There are multiple contact plugs 21_1 to 22_4 that electrically connect the drain 25 of the transistor 20 to the light-emitting element 23, and wiring 27 made up of multiple metal wirings 22_1 to 22_4, with an insulating layer 28 provided between the wirings. While Figure 15 illustrates the insulating layer 28 as a single layer, the insulating layer 28 may have a stacked structure made up of multiple layers.

The light-emitting element 23 can be composed of a first electrode 13, an organic film 14 having a light-emitting layer, and a second electrode 15. In Figure 15, the organic film 14 is illustrated as a single layer, but the organic film 14 may be composed of multiple layers. In the light-emitting element 23, the second electrode 14 is a transparent electrode, and light from the organic film 14 is extracted to the outside through the second electrode 15. A protective layer 16 is provided on the second electrode 15 to reduce deterioration of the light-emitting element 23. The second electrode 15 of the light-emitting element 23 is shared by multiple light-emitting elements 23 and serves as a common electrode.

In a light-emitting element array, structural units each consisting of a combination of a light-emitting element 23 and a transistor 20 can be repeatedly arranged in the row and column directions. The electrical connection method between the light-emitting element 23 and the electrodes (source electrode, drain electrode) included in the transistor 20 is not limited to the form shown in Figure 15. Depending on the polarity of the first electrode 13 of the light-emitting element 23 and the polarity of the transistor 20, it is sufficient that either the source electrode or the drain electrode of the transistor 20 is electrically connected to the first electrode 13 of the light-emitting element 23. In Figure 15, a transistor is used as the switching element, but other switching elements may be used instead.

Furthermore, the transistor 20 is not limited to a transistor formed on a single-crystal silicon wafer, but may also be a thin-film transistor having an active layer on the insulating surface of a substrate. Examples of active layers include non-single-crystal silicon such as single-crystal silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide.

The moisture-resistant ring 7 and the protective layer 16 of the light-emitting element 23 are in physical contact, reducing or preventing the penetration of moisture from the outside into the light-emitting element 23. At least one of the multiple contact plugs 21_1-22_4 and multiple metal wirings 22_1-22_4 that make up the moisture-resistant ring 7 may be partially replaced with a layer of the same material as the protective layer 16. Because the protective layer 16 is made of a material that can reduce moisture penetration, the moisture resistance of the moisture-resistant ring 7 can be maintained even with such a substitution. In this embodiment, a structure having such a substitution is also referred to as a moisture-resistant ring.

In the example shown in FIG. 6 , contact-tolerant regions 10, with which the protrusions 6 of the deposition mask 4 come into contact, are provided in two locations on the light-emitting device. Therefore, in the plan view (top view) shown in FIG. 6 , the moisture-resistant wall 71 constituting part of the first moisture-resistant ring 7 has two recesses away from the first edge S1, and the contact-tolerant regions 10 are located in these recesses. Components such as pads, drive circuits, and contact regions are not present in the contact-tolerant regions 10. By expanding the contact-tolerant regions 10 as much as possible, the protective region surrounded by the first moisture-resistant ring 7 is narrowed, reducing the possibility of defects occurring in the protective region and improving the reliability of the light-emitting device 2. Possible defects in the protective region include moisture penetration due to damage to the protective film 16 on the protective region.

The pattern portion PP of the deposition mask 4 is separated from the material substrate 1 by the protrusions 6. If the gap between the pattern portion PP and the material substrate 1 (the height of the protrusions 6) is too large, a film may be formed by deposition on the material substrate 1 over an area wider than the openings 5 of the pattern portion PP. Therefore, the gap between the pattern portion PP and the material substrate 1 (the height of the protrusions 6) is preferably, for example, 20 μm or less, and more preferably 10 μm or less. The minimum value of the gap between the pattern portion PP and the material substrate 1 (the height of the protrusions 6) can be determined to ensure that the pattern portion PP and the material substrate 1 do not come into contact with each other.

The spacing between adjacent protrusions 6 can also be considered. If the spacing between adjacent protrusions 6 is too wide, the pattern portion PP of the deposition mask 4 and the material substrate 1 may come into contact with each other in the areas between the protrusions 6. Table 1 illustrates the results of checking whether the pattern portion PP and the material substrate 1 come into contact with each other while varying the spacing between the protrusions 6 and the thickness (plate thickness) of the pattern portion PP. The height of the protrusions 6 was 10 μm, the magnetic force for fixing the deposition mask 4 to the material substrate 1 was 150 gauss, and the spacing between adjacent openings 5 in the Y direction was 250 μm. The contact between the pattern portion PP and the material substrate 1 was evaluated by measuring particles in areas of the material substrate 1 other than the contact-permitted area 10 after the protrusions 6 of the deposition mask 4 were brought into contact with the material substrate 1 using a particle counter. Here, if there were no particles, it was marked "no contact" (○), and if there were particles, it was marked "contact" (×).

FIG. 9 shows the configuration of a light emitting device 2" of the comparative example. The light emitting device 2" of the comparative example has a rectangular moisture-resistant ring 7, and a contact-tolerant region 10 is arranged outside the moisture-resistant ring 7. In such a configuration, the dimension f in the Y direction of the unit consisting of the light emitting device 2" and the contact-tolerant region 10 is larger than the dimension e in the Y direction (second direction) of the light emitting device 2". This can reduce the number of light emitting devices 2" that can be obtained from one material substrate 1.

A manufacturing method for producing the light emitting device 2 of the first embodiment may include a vapor deposition process in which a functional layer formation material is deposited using a vapor deposition mask 4 on a material substrate 1 having multiple rectangular substrate regions that will each become a rectangular substrate RS. Each of the multiple rectangular substrate regions of the material substrate 1 has a contact tolerance region 10 between the first side S1 and a portion of the moisture-resistant wall 71 that defines the shortest distance d1. The vapor deposition mask 4 may include multiple protrusions 6 that respectively contact the contact tolerance regions 10 in the multiple rectangular substrate regions, and a pattern portion PP having multiple openings 5. In the vapor deposition process, the multiple protrusions 6 define the distance between the material substrate 1 and the pattern portion PP.

The light-emitting device 2 of the second embodiment will now be described with reference to Figure 10. Figure 10 schematically shows the configuration of one light-emitting device 2 in the second embodiment. Note that matters not mentioned in the second embodiment may follow those of the first embodiment unless they cause any contradictions.

The light-emitting device 2 may include a moisture-resistant ring structure 70 disposed on the rectangular substrate RS to prevent moisture from penetrating the light-emitting element array 3 and all pads 8. The moisture-resistant ring structure 70 may include moisture-resistant walls 71, 72 disposed between the light-emitting element array 3 and the first edge S1. In FIG. 10 , the moisture-resistant walls 71, 72 in the moisture-resistant ring structure 70 are indicated by bold gray lines. The shortest distance between the light-emitting element array 3 and the moisture-resistant walls 71, 72 in the Y direction (second direction) is distance d1'. The distance between the light-emitting element array 3 and the moisture-resistant walls 71 on an imaginary line VSL parallel to the Y direction (second direction) and passing through the light-emitting element array 3 and the pads 8 is distance d2. In the second embodiment, distance d1' is smaller than distance d2. This reduces the distance (spacing) between adjacent light-emitting devices 2 in the Y direction on the material substrate 1, thereby increasing the number of light-emitting devices 2 that can be formed on the material substrate 1 and reducing the manufacturing costs of the light-emitting devices 2.

The moisture-resistant ring structure 70 may include a first moisture-resistant ring 7 arranged to surround the light-emitting element array 3 and pads 8, and a second moisture-resistant ring 11 arranged to be surrounded by the first moisture-resistant ring 7 but not surrounding the light-emitting element array 3 and pads 8. The first moisture-resistant ring 7 may include a portion that defines the distance d2 between the light-emitting element array 3 and the moisture-resistant walls 71, 72 on the imaginary line VSL, and the second moisture-resistant ring 11 may include a portion that defines the shortest distance d1' between the light-emitting element array 3 and the moisture-resistant walls 71, 72. The first moisture-resistant ring 7 may be arranged to surround the light-emitting element array 3 and pads 8 all around. The second moisture-resistant ring 11 may be arranged to surround the structure arranged inside the second moisture-resistant ring 11 all around.

The light-emitting device 2 of the third embodiment will now be described with reference to Figure 11. Figure 11 schematically shows the configuration of one light-emitting device 2 in the third embodiment. Please note that matters not mentioned in the third embodiment may follow at least one of the first and second embodiments, provided no contradictions arise.

The light-emitting device 2 may include a moisture-resistant ring structure 70 disposed on the rectangular substrate RS to prevent moisture from penetrating the light-emitting element array 3 and all pads 8. The moisture-resistant ring structure 70 may include moisture-resistant walls 71, 72 disposed between the light-emitting element array 3 and the first edge S1. In FIG. 11 , the moisture-resistant walls 71, 72 in the moisture-resistant ring structure 70 are indicated by bold gray lines. The shortest distance between the light-emitting element array 3 and the moisture-resistant walls 71, 72 in the Y direction (second direction) is distance d1'. In the example of FIG. 11 , both the shortest distance between the light-emitting element array 3 and the moisture-resistant wall 71 in the Y direction (second direction) and the shortest distance between the light-emitting element array 3 and the moisture-resistant wall 72 in the Y direction (second direction) are distance d1'. However, at least one of the shortest distance between the light-emitting element array 3 and the moisture-resistant wall 71 in the Y direction (second direction) and the shortest distance between the light-emitting element array 3 and the moisture-resistant wall 72 in the Y direction (second direction) may be distance d1'. The distance between the light-emitting element array 3 and the moisture-resistant wall 71 on an imaginary line VSL that is parallel to the Y direction (second direction) and passes through the light-emitting element array 3 and the pads 8 is d2. In the third embodiment, the distance d1' is smaller than the distance d2. This reduces the distance (spacing) between adjacent light-emitting devices 2 in the Y direction on the material substrate 1, thereby increasing the number of light-emitting devices 2 that can be formed on the material substrate 1 and reducing the manufacturing cost of the light-emitting devices 2.

The moisture-resistant ring structure 70 may include a first moisture-resistant ring 7 arranged to surround the light-emitting element array 3 and pads 8, and a second moisture-resistant ring 11 arranged to be surrounded by the first moisture-resistant ring 7 but not surrounding the light-emitting element array 3 and pads 8. The first moisture-resistant ring 7 may include a portion that defines the distance d2 between the light-emitting element array 3 and the moisture-resistant walls 71, 72 on the imaginary line VSL. At least one of the first moisture-resistant ring 7 and the second moisture-resistant ring 11 may include a portion that defines the shortest distance d1' between the light-emitting element array 3 and the moisture-resistant walls 71, 72. The first moisture-resistant ring 7 may be arranged to surround the entire periphery of the light-emitting element array 3 and pads 8. The second moisture-resistant ring 11 may be arranged to surround the entire periphery of the structure arranged inside the second moisture-resistant ring 11.

The light-emitting device 402 of the fourth embodiment will be described below with reference to Figures 16 to 21. It should be noted that matters not mentioned in the fourth embodiment may conform to at least one of the first to third embodiments unless a contradiction arises. The numerical values, shapes, materials, components, component arrangements, and connection configurations described herein do not limit the scope of the disclosure unless expressly stated to be limiting.

In the following, an OLED will be used as an example of a light-emitting element. Note that this disclosure is not limited to OLEDs, and can be applied to current-driven light-emitting devices in general.

Figure 16(a) shows an example in which a light-emitting device 402 according to the fourth embodiment is formed on a material substrate 401 such as a silicon wafer. The light-emitting devices 402 can be formed in a matrix on the substrate 401. In the case of rectangular light-emitting devices 402, the yield per material substrate 401 varies greatly depending on the size of the short side, so making the short side as short as possible is effective in reducing costs. Furthermore, when a silicon wafer is used as the substrate for manufacturing the light-emitting device 402, it becomes possible to form the drive circuitry finely. As a result, it becomes possible to increase the density of the OLED. This increase in density enables the formation of higher-resolution images.

Figure 16(b) shows an example of a vapor deposition mask 403 for forming an OLED on a light-emitting device 402. The vapor deposition mask 403 has multiple openings 404 arranged at equal intervals between the multiple openings 404 and the multiple light-emitting devices 402. After the light-emitting devices 402 on the material substrate 401 and the openings 404 in the vapor deposition mask 403 are overlapped in plan view, the material substrate 401 and the ribs 405 of the vapor deposition mask 403 are brought into close contact, and electrodes and organic layers are vapor-deposited onto the light-emitting device by vacuum vapor deposition to form an OLED.

Figure 16(c) shows an example of the cross-sectional structure when the material 401 and the ribs 405 of the deposition mask 403 are in close contact. The ribs 405 of the deposition mask 403 make it possible to maintain a constant distance between the material substrate 401 and the pattern portion of the deposition mask 403 (portions other than the ribs 405) when the material substrate 401 and the ribs 405 of the deposition mask 403 are in close contact with each other. The ribs 405 also minimize the area where the deposition mask 403 comes into contact with the light-emitting device 402, preventing foreign matter from being transferred to and scratches on the light-emitting device 402 and preventing sealing defects.

Figure 17 is a cross-sectional schematic diagram showing an example of an OLED 420 and a transistor 414 connected to the OLED 420. The transistor is an example of an active element. The transistor may be a thin-film transistor (TFT). Figure 17 shows the OLED 420 and the transistor 414. The drain 412 and source 411 of the transistor 414 are disposed on the silicon substrate 410, and the gate 413 of the transistor 414 is disposed on the silicon substrate 410 via a gate insulating film (not shown).

There are multiple contact plugs 415_1 to 415_4 that electrically connect the drain 412 of the transistor 414 to the OLED 420, and wiring 417 consisting of multiple metal wirings 416_1 to 416_4, with insulating layers 419 provided between each wiring. Insulating layer 419 is illustrated as a single layer in Figure 17, but insulating layer 419 may have a stacked structure consisting of multiple layers.

The OLED 420 can be composed of a first electrode 416-4, an organic film 421 having an emitting layer, and a second electrode 422. Although the organic film 421 is illustrated as a single layer in FIG. 17, the organic film 421 may be composed of multiple layers. In the OLED 420, the second electrode 422 is a transparent electrode, and light from the organic film 421 is extracted to the outside through the second electrode 422. A protective layer 425 is provided on the second electrode 422 to reduce deterioration of the OLED 420. The second electrode 422 of the OLED 420 is shared by multiple OLEDs 420 and serves as a common electrode.

In the light-emitting device 402, structural units each consisting of a combination of an OLED 420 and a transistor 414 are repeatedly arranged in the row and column directions. Between each OLED 420, a structure 427 having a large step may be formed in the layer directly below the organic film 421. The structure 427 may be formed to electrically isolate the organic film 421 while electrically connecting the second electrode 422. The electrical connection between the OLED 420 and the electrodes (source electrode, drain electrode) included in the transistor 414 is not limited to the form shown in FIG. 17. Depending on the polarity of the OLED 420 and the first electrode 416_4 and the polarity of the transistor 414, either the source electrode or the drain electrode of the transistor 414 may be electrically connected to the first electrode 416_4 of the OLED 420. While a transistor is used as the switching element in FIG. 17, other switching elements may be used instead.

In addition, the transistor is not limited to a transistor formed on a single-crystal silicon wafer, but may also be a thin-film transistor having an active layer on the insulating surface of a substrate. Examples of active layers include single-crystal silicon, amorphous silicon, microcrystalline silicon, and other non-single-crystal silicon, as well as non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide.

Figure 18 is a schematic diagram showing one form of a light-emitting device 402 according to the fourth embodiment. The light-emitting device 402 of the fourth embodiment has a rectangular shape with long sides parallel to the first direction and short sides parallel to a direction intersecting the first direction.

In the light-emitting device 402, when the light-emitting region 102 is formed along the long side direction, components other than the light-emitting region 102, such as contact regions, can be arranged in the peripheral region of the light-emitting region 102, in the region adjacent to the light-emitting region 102 in the short side direction.

The substrate 101 has a rectangular shape. In this specification, the long side direction of the rectangular substrate 101 is referred to as the first direction, and the short side direction perpendicular to the long side direction is referred to as the second direction. A moisture-resistant ring 100 is disposed on the rectangular substrate 101, and serves to prevent moisture from entering the light-emitting device 402. In addition, a light-emitting region 102, a first contact region 103_1, a second contact region 103_2, and pads 104_1 and 104_2 are disposed in the area surrounded by the moisture-resistant ring 100. A plurality of light-emitting elements are arranged in a matrix in the light-emitting region 102. The first contact region 103_1 and the second contact region 103_2 are regions where wiring is disposed that electrically connects to the common electrode of the OLED. The pads 104_1 and 104_2 are electrically connected to the contact regions.

In the light-emitting region 102, multiple light-emitting elements are arranged in a matrix. As described above, each light-emitting element is composed of a light-emitting layer and a first electrode and a second electrode that sandwich the light-emitting layer. The first electrode is an independent electrode provided for each light-emitting element, and the second electrode is a common electrode provided for all light-emitting elements.

The first contact region 103_1 and the second contact region 103_2 are provided in an area adjacent to the light-emitting region 102 of the substrate 101 and surrounded by the moisture-resistant ring 100. The recess 105, the first contact region 103_1 and the second contact region 103_2, and the pads 104_1 and 104_2 are arranged between the light-emitting region 102 and one long side end of the substrate 101. In other words, the recess 105, the first contact region 103_1 and the second contact region 103_2, and the pads 104_1 and 104_2 can be arranged in the direction of one short side when viewed from the light-emitting region 102. The recess 105 can be arranged between the first contact region 103_1 and the second contact region 103_2. Furthermore, the recess 105, the first contact region 103_1 and the second contact region 103_2, and the pads 104_1 and 104_2 are arranged in series along the long side direction. In the example of FIG. 18, the pad 104_1, the first contact region 103_1, the recess 105, the second contact region 103_2, and the pad 104_2 are arranged in series along the long side direction in this order.

The moisture-resistant ring 100 is a guard ring made of a wiring layer and is arranged to surround the light-emitting region 102, the first contact region 103_1, the second contact region 103_2, and the pads 104_1 and 104_2. The moisture-resistant ring 100 may have one or more recesses 105 on one of the long sides of the substrate. The moisture-resistant ring 100 may have a narrow portion 100_2 and wide portions 100_1 and 100_3, respectively, arranged on both sides of the narrow portion 100_2 in the long side direction (first direction). The width of the narrow portion 100_2 in the short side direction (second direction) may be shorter than the width of the wide portions 100_1 and 100_3 in the short side direction, and the width of the wide portions 100_1 and 100_3 in the short side direction may be longer than the width of the narrow portion 100_2 in the short side direction. The position of one of the long sides of the narrow portion 100_2 and the wide portions 100_1 and 100_3 in the short-side direction may be the same, and the position of the other long side in the short-side direction may be different. Due to the presence of the narrow portion 100_2, the moisture-resistant ring 100 has a concave portion on its outer periphery. This portion is referred to as the recess 105 in this embodiment. The recess 105 may be used as a contact region for abutting a rib 405, which is part of the vapor deposition mask 403, during the film formation process. The narrow portion 100_2 may have a shorter width in the short-side direction than the wide portions 100_1 and 100_3 by the width of the recess 105 in the short-side direction. The first contact region 103_1 and the second contact region 103_2 are disposed inside the wide portions 100_1 and 100_3 of the moisture-resistant ring 100, respectively.

A drive circuit for the light-emitting device 402 may be formed inside the moisture-resistant ring 100 (not shown). During OLED formation, the rib 005 of the vapor deposition mask 403 abuts against the recess 105 of the moisture-resistant ring 100, or in other words, the outside of the moisture-resistant ring 100 at the narrow portion 100_2, maintaining a constant distance between the substrate and the pattern portion of the mask 403. The rib 405 minimizes the contact surface between the vapor deposition mask 403 and the light-emitting device 402, preventing foreign matter from being transferred to and scratching the light-emitting device 402 and preventing sealing defects. Furthermore, if the rib 405 abuts against the substrate, scratches may be generated in the insulating film on the substrate, potentially reducing the sealing performance of the light-emitting device 402. In this embodiment, the recess 105, which serves as the abutment area for the rib 405, is positioned on the outside of the moisture-resistant ring to ensure the sealing performance of the light-emitting device 402.

The second electrode (upper electrode/common electrode) 422 of the OLED in this embodiment is made of a transparent electrode material, and therefore has a relatively high wiring resistance. Furthermore, because the second electrode 422 is also a common electrode, current flows from multiple OLEDs, resulting in a large voltage drop across the second electrode 422. Therefore, differences in the voltage applied to each OLED can occur depending on the distance from the contact region where the potential is supplied. This can result in differences in actual emission brightness between OLEDs to which a voltage is applied to emit light with the same brightness, potentially resulting in shading and other issues.

The light-emitting device 402 of this embodiment may have at least two contact regions (103_1, 103_2) between the second electrode (upper electrode/common electrode) 422 and the power supply wiring along the long side edge of the light-emitting device 402. By having the second electrode 422 contact the low-resistance power supply wiring at multiple positions along the long side, it is possible to reduce the voltage drop in the second electrode 422. Therefore, even if multiple OLEDs have a common second electrode 422, it is possible to reduce the voltage drop that depends on the position of the second electrode 422 and suppress shading in the emitted light brightness.

It is also possible to arrange the first contact region 103_1 or the second contact region 103_2 and the abutment region of the rib 405 of the vapor deposition mask 403 in series along the short side of the light emitting device 402. However, in that case, a dedicated rib area would be provided between the light emitting devices 402 in the short side direction, and the size of the light emitting device 402 would increase by the amount of the dedicated rib area. In the light emitting device 402 of this embodiment, the recess 105 of the moisture-resistant ring, which is the rib abutment area, is arranged between the first contact region 103_1 and the second contact region 103_2, thereby reducing the distance between the light emitting devices 402 in the short side direction. This increases the number of light emitting devices 402 that can be arranged in the short side direction on a single substrate, thereby improving yield.

Figure 19 is an E-E' cross-sectional view of the light-emitting device 402 of Figure 18. The moisture-resistant ring 100_2 has a layered structure in which contact plugs 445_1 to 445_4 and metal wiring 446_1 to 446_4 are stacked, and extends from the surface of the light-emitting device 402 to a depth that reaches the silicon substrate 410 on which the circuit elements are formed. The contact plugs 445_1 to 445_4 and metal wiring 446_1 to 446_4 that make up the moisture-resistant ring 100_2 are formed in the same layer as the contact plugs 415_1 to 415_4 and metal wiring 416_1 to 416_4 that make up the wiring 417. In this way, the moisture-resistant ring 100_2 has the same layer structure as the multilayer wiring structure of the internal circuit, and can be formed simultaneously with the internal circuit using common processes.

The cross-sectional structure of the moisture-resistant ring 100_1 can have the same structure as the moisture-resistant ring 040_2 at any location within the light-emitting device 402.

In addition, the moisture-resistant rings 100_1 and 100_2 are in physical contact with the protective layer 025 of the OLED 420, which serves to prevent moisture from penetrating into the OLED 420.

In the scribe area 441, the protective layer 425 of the OLED 420 is removed. This prevents the protective layer 425 from chipping when the light-emitting device 402 is cut from the silicon substrate 410.

In the contact region 103_1, the second electrode (common electrode) 422 of the OLED 420 and the metal wiring 456_4 are in physical contact. The pad 104_1 is composed of metal wiring in the same layer as the metal wiring 456_3. A low-resistance metal wiring 456_3 is drawn from the pad 104_1 to directly below the contact region 103_1, and a contact plug 455-4 provides low-resistance electrical conduction between the metal wiring 456_3 and the metal wiring 456_4. In this embodiment, the pad 104_1 is in the same layer as the metal wiring 456_3, but it may also be in the same layer as the metal wiring 456_4, for example.

By adopting the configuration described in this embodiment, it is possible to suppress shading in the brightness of the light-emitting device 402 while improving yield and achieving low-cost manufacturing.

The light-emitting device 402 of the fifth embodiment will be described below with reference to Figure 20. It should be noted that matters not mentioned in the fifth embodiment may follow those of the fourth embodiment unless a contradiction arises. Figure 20 is a schematic diagram showing the configuration of the light-emitting device of the fifth embodiment.

Arranged on the rectangular substrate 101 are a moisture-resistant ring 200, a light-emitting area 102 in which light-emitting pixels are arranged in rows and columns, contact areas 203_1 to 203_5 that electrically connect to the OLED common electrode, and pads 204_1 to 204_3 that electrically connect to the contact areas.

In this embodiment, the moisture-resistant ring 200 is configured by alternating five wide portions 200_1, 200_3, 200_5, 200_7, and 200_9 and four narrow portions 200_2, 200_4, 200_6, and 200_8. The narrow portions 200_2, 200_4, 200_6, and 200_8 have a shorter width in the short side direction than the wide portions 200_1, 200_3, 200_5, 200_7, and 200_9. While an example with four narrow portions is shown here, the number is not particularly limited.

Due to the presence of the wide portions 200_1, 200_3, 200_5, 200_7, and 200_9, the outer peripheral shape of the moisture-resistant ring 200 includes multiple recessed portions. These portions are referred to as recessed portions 205_1 to 205_4 of the moisture-resistant ring. Recessed portions 205_1 to 205_4 may be used as contact areas for ribs, which are part of a deposition mask, during the film-forming process. In this embodiment, multiple recessed portions 205_1 to 205_4 of the moisture-resistant ring 200 are arranged along the long sides of the light-emitting device. This allows for narrower spacing between the rib contact areas on the substrate 101, thereby suppressing deflection of the deposition mask. Furthermore, narrowing the spacing between the rib contact areas allows for shorter lengths of each recessed portion, which serves as a contact area, along the long sides, and thus reduces the distance between the first and second contact regions. This further reduces the resistance of the common electrode in the center of the light-emitting device, thereby further suppressing brightness shading in the light-emitting device. By alternately arranging the common electrode and power supply wiring contact regions 203_1-203_3 and the moisture-resistant ring recesses 205_1-205_3 on the light-emitting device, the resistance of the common electrode can be reduced in multiple locations.

By arranging components other than the light-emitting region, such as the contact region of the light-emitting device, in series in the long side direction, the light-emitting device can be further miniaturized, increasing the yield on the substrate and reducing costs. In this specification, "component A and component B being in series in a first direction" means that component A and component B have an overlapping portion when viewed in plan from the first direction on a surface perpendicular to the first direction.

The light-emitting device 402 of the sixth embodiment will be described below with reference to FIG. 21. Note that matters not mentioned in the sixth embodiment may follow those of the fifth embodiment unless a contradiction arises. FIG. 21 is a schematic diagram showing the configuration of a light-emitting device according to the sixth embodiment. Compared to the light-emitting device of FIG. 20, circuits 206_1 and 206_2 for driving the light-emitting elements have been added. The circuits 206_1 to 206_2 are arranged in series along the long side. In other words, the circuits 206_1 to 206_3 are additionally arranged so as to overlap in a plan view perpendicular to the long side. The circuits 206_1 to 206_2 are also arranged in series along the long side with the contact regions 203_1 to 203_3 and the pads 204_1 to 204_3.

Specific examples of circuits 206_1-206_2 include, but are not limited to, input protection circuits, input circuits to which drive data is input, and logic circuits for processing data. Regardless of the type of circuit, by locating the circuit area in the same position along the short side as the contact area and pad area and arranging the circuit in this circuit area, it is possible to reduce the length of the light-emitting device along the short side.

Figure 22 is a cross-sectional view of the light-emitting device of Figure 21 taken along the line F-F'. Compared to Figure 19, circuits 206_1 and 206_2 have been added.

By adopting the configuration described in this embodiment, shading of the brightness of the light-emitting device can be effectively suppressed.

An image forming apparatus 100 incorporating a light-emitting device 2 representative of the first to sixth embodiments will now be described with reference to FIG. 12. FIG. 12 schematically illustrates the configuration of the image forming apparatus 100. The image forming apparatus 100 may be configured as an electrophotographic image forming apparatus. The image forming apparatus 100 may include a photoreceptor 101, a charging unit 102 that charges the photoreceptor 101, an exposure unit 103 that exposes the surface of the photoreceptor 101 to light to form an electrostatic latent image on the surface, and a development unit 104 that develops the electrostatic latent image. The exposure unit 103 may include the light-emitting device 2 described above as a light source. The development unit 104 may form an image, for example, by attaching toner to the electrostatic latent image. The image forming apparatus 100 may further include a transfer unit 105 that transfers the image formed by the development unit 104 to a recording medium 107, and a fixing unit 108 that fixes the image transferred to the recording medium 107.

In the figure, the X direction represents columns (the direction in which the light is arranged), and the Y direction represents rows (the direction in which the light is arranged). Here, the X direction may be along the rotational axis of the photosensitive element 101 of the image forming apparatus 100. Multiple light-emitting devices 2 may be arranged to form a light source for the exposure unit 103. In one example, multiple light-emitting devices 2 may be arranged in a staggered configuration, as illustrated in FIG. 13. The light-emitting elements in each light-emitting element array 3 may be arranged in a single row or multiple rows. Arranging the light-emitting elements in multiple rows in each light-emitting element array 3 is advantageous for gradation expression and for reducing the light emission output of each light-emitting element and extending the life of the light-emitting elements. When arranging the light-emitting elements in multiple rows in each light-emitting element array 3, if there are four rows of light-emitting elements, as illustrated in FIG. 14, the initial positions of the light-emitting elements in the first row and the second row may be offset in the X direction by 1/4 of the X-direction dimension of the light-emitting elements. In the case of n rows, the initial positions of the light-emitting elements in the first row and the second row may be shifted in the X direction by 1/n of the X-direction dimension of the light-emitting elements. This configuration is advantageous for improving resolution.

Hereinafter, each component of the light emitting device 2 will be described in detail by way of example.
[Configuration of organic light-emitting element]
The organic light-emitting element is provided by forming an insulating layer, a first electrode, an organic film, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc. may be provided on the cathode. When a color filter is provided, a planarizing layer may be provided between the protective layer. The planarizing layer may be made of acrylic resin, etc. The same applies when a planarizing layer is provided between the color filter and the microlens.
[substrate]
Examples of the substrate include quartz, glass, a silicon wafer, a resin, and a metal. Furthermore, the substrate may be provided with a switching element such as a transistor and wiring, and an insulating layer thereon. Any material can be used for the insulating layer, as long as it allows for the formation of a contact hole so that wiring can be formed between the first electrode and the insulating layer, and ensures insulation from wiring that is not connected. For example, resins such as polyimide, silicon oxide, silicon nitride, etc. can be used.
[electrode]
A pair of electrodes can be used. 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 element 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.

The material that makes up the anode should have as high a work function as possible. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, as well as mixtures containing these metals or alloys combining these metals, and metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide can also be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

One of these electrode materials may be used alone, or two or more may be used in combination. The anode may consist of a single layer or multiple layers.

When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates of these can be used. The above materials can also function as a reflective film without acting as an electrode. Furthermore, when used as a transparent electrode, transparent conductive oxide layers such as indium tin oxide (ITO) and indium zinc oxide can be used, but are not limited to these. Photolithography techniques can be used to form the electrode.

On the other hand, materials with a low work function are preferred for the cathode. Examples include alkali metals such as lithium, alkaline earth metals such as calcium, and metals such as aluminum, titanium, manganese, silver, lead, and chromium, as well as mixtures containing these. Alloys combining these metals can also 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. These electrode materials can be used alone or in combination. The cathode can have either a single-layer or multi-layer structure. Among these, silver is preferred, and a silver alloy is even more preferred to reduce silver agglomeration. The alloy ratio is not important as long as silver agglomeration is reduced. For example, the silver:other metal ratio can be 1:1, 3:1, etc.

The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but DC and AC sputtering methods are more preferable because they provide good film coverage and make it easier to reduce resistance.
[Pixel isolation layer]
The pixel separation layer is formed of a silicon nitride (SiN) film, a silicon oxynitride (SiON) film, or a silicon oxide (SiO) film formed using a chemical vapor deposition (CVD) method. To increase the in-plane resistance of the organic film, it is preferable that the organic film, particularly the hole transport layer, be thinly formed on the sidewall of the pixel separation layer. Specifically, the thickness of the sidewall can be thinned by increasing the taper angle of the sidewall of the pixel separation layer or the thickness of the pixel separation layer, thereby increasing vignetting during deposition.

On the other hand, it is preferable to adjust the sidewall taper angle and film thickness of the pixel separation layer to such an extent that voids are not formed in the protective layer formed on top of it. Since voids are not formed 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, it is possible to reduce reliability degradation such as the occurrence of dark spots and poor conductivity of the second electrode.

According to this embodiment, charge leakage to adjacent pixels can be effectively suppressed even if the taper angle of the sidewall of the pixel separation layer is not steep. As a result of this study, it was found that sufficient reduction is possible if the taper angle is in the range of 60 degrees or more and 90 degrees or less. The thickness of the pixel separation layer is preferably 10 nm or more and 150 nm or less. Similar effects can also be achieved even if the pixel electrode is composed only of a pixel electrode without a pixel separation layer. However, in this case, it is preferable that the thickness of the pixel electrode be half or less than that of the organic layer, or that the edge of the pixel electrode be forward tapered at less than 60 degrees, in order to reduce short circuits in the organic light-emitting element.
[Organic film]
The organic film may be formed as a single layer or as multiple layers. When multiple layers are included, they may be called hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, or electron injection layer depending on their functions. The organic film is mainly composed of organic compounds, but may also contain inorganic atoms or inorganic compounds. For example, the organic film may contain copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, or the like. The organic film may be disposed between the first electrode and the second electrode, or may be disposed in contact with the first electrode and the second electrode.

When a plurality of light-emitting layers are provided, a charge generation portion may be provided between the first light-emitting layer and the second light-emitting layer. The charge generation portion may include an organic compound having a lowest unoccupied molecular orbital energy (LUMO) of −5.0 eV or less. The same applies when a charge generation portion is provided between the second light-emitting layer and the third light-emitting layer.
[Protective layer]
A protective layer may be provided on the second electrode. For example, by adhering glass provided with a moisture absorbent to the second electrode, the infiltration of water and the like into the organic film can be reduced, thereby reducing the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the cathode to reduce the infiltration of water and the like into the organic film. For example, after forming the cathode, the cathode may be transported to another chamber without breaking the vacuum, and a 2 μm-thick silicon nitride film may be formed by CVD to serve as a protective layer. A protective layer may be provided using atomic layer deposition (ALD) after the CVD film formation. The material of the film formed by ALD is not limited, and may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be further formed on the film formed by ALD by CVD. The film formed by ALD may have a thickness smaller than that of the film formed by CVD. Specifically, it may be 50% or less, or even 10% or less.
[Color filter]
A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on a separate substrate and then bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer described above using photolithography technology. The color filter may be made of a polymer.
[Planarization layer]
A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing the unevenness of the underlying layer. It may also be called a material resin layer without limiting its purpose. The planarization layer may be composed of an organic compound, and may be either a low molecular weight or a high molecular weight, but a high molecular weight is preferred.

The planarizing layer may be provided above or below the color filter, and may be made of the same or different materials, such as polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.
[Microlens]
The organic light-emitting device may have an optical component such as a microlens on its light-emitting side. The microlens may be made of acrylic resin, epoxy resin, or the like. The microlens may be used to increase the amount of light extracted from the organic light-emitting device and to control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents to the hemisphere, there is a tangent that is parallel to the insulating layer, and the point of contact between this tangent and the hemisphere is the vertex of the microlens. The vertex of the microlens can be determined in the same way in any cross-sectional view. In other words, among the tangents to the semicircle of the microlens in the cross-sectional view, there is a tangent that is parallel to the insulating layer, and the point of contact between this tangent and the semicircle is the vertex of the microlens.

The midpoint of a microlens can also be defined. In the cross section of the microlens, a line segment can be imagined from the point where an arc shape ends to the point where another arc shape ends, and the midpoint of this line segment can be called the midpoint of the microlens. The cross section used to determine the vertex and midpoint may be a cross section perpendicular to the insulating layer.

The microlens has a first surface having a convex portion and a second surface opposite the first surface. It is preferable that the second surface is disposed closer to the functional layer than the first surface. To achieve this configuration, it is necessary to form the microlens on the light-emitting device. When the functional layer is an organic layer, it is preferable to avoid processes that result in high temperatures during the manufacturing process. Furthermore, when the second surface is disposed closer to the functional layer than the first surface, it is preferable that the glass transition temperatures of all of the organic compounds that make up the organic layer are 100°C or higher, and more preferably 130°C or higher.
[Counter substrate]
An opposing substrate may be provided on the planarization layer. The opposing substrate is called an opposing substrate because it is provided at a position corresponding to the aforementioned substrate. The constituent material of the opposing substrate may be the same as that of the aforementioned substrate. When the aforementioned substrate is defined as a first substrate, the opposing substrate may be a second substrate.
[Organic layer]
The organic films (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light emitting device according to one embodiment of the present invention are formed by the method shown below.

The organic film that constitutes the organic light-emitting device according to one embodiment of the present invention can be formed using dry processes such as vacuum deposition, ionization deposition, sputtering, and plasma. Instead of a dry process, a wet process can also be used in which the material is dissolved in an appropriate solvent and a layer is formed using a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

Here, if a layer is formed using a vacuum deposition method or solution coating method, crystallization is unlikely to occur and the layer has excellent stability over time. Furthermore, when forming a film using a coating method, it is also possible to form a film by combining it with an appropriate binder resin.

Examples of the binder resin include, but are not limited to, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

These binder resins may be used singly as homopolymers or copolymers, or as a mixture of two or more types. Furthermore, known additives such as plasticizers, antioxidants, and ultraviolet absorbers may be used in combination, if necessary.

The disclosure of the present specification and drawings will be described below by way of example. The present specification and drawings disclose at least the following items.
(Item 1)
A light emitting device having a rectangular substrate having first and second sides parallel to a first direction and third and fourth sides parallel to a second direction perpendicular to the first direction,
a light-emitting element array configured with a plurality of light-emitting elements arranged on the rectangular substrate;
a pad disposed on the rectangular substrate so as to be located between the first side and the light-emitting element array;
a moisture-resistant ring structure disposed on the rectangular substrate so as to prevent moisture from entering the light-emitting element array and the pads;
the moisture-resistant ring structure includes a moisture-resistant wall disposed between the light-emitting element array and the first side,
the shortest distance between the light-emitting element array and the moisture-resistant wall in the second direction is shorter than the distance between the light-emitting element array and the moisture-resistant wall on an imaginary line that is parallel to the second direction and passes through the light-emitting element array and the pad;
A light emitting device characterized by:
(Item 2)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad;
the moisture-resistant wall is a part of the first moisture-resistant ring;
2. The light emitting device according to claim 1.
(Item 3)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
2. The light emitting device according to claim 1.
(Item 4)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
at least one of the first moisture-resistant ring and the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
2. The light emitting device according to claim 1.
(Item 5)
the first moisture-resistant ring is disposed so as to surround the entire periphery of the light-emitting element array;
5. The light emitting device according to any one of items 2 to 4.
(Item 6)
the first moisture-resistant ring is disposed so as to surround the light-emitting element array and the pads over the entire periphery;
the second moisture-proof ring is disposed so as to surround the entire periphery of the structure disposed inside the second moisture-proof ring;
5. The light-emitting device according to item 3 or 4.
(Item 7)
the minimum rectangle circumscribing the light-emitting element array has a dimension in the first direction greater than a dimension in the second direction;
5. The light emitting device according to any one of items 2 to 4.
(Item 8)
Each of the plurality of light-emitting elements includes a plurality of functional layers made of an organic material.
8. The light emitting device according to any one of items 1 to 7.
(Item 9)
a plurality of contact regions disposed on the rectangular substrate to receive signals or potentials for driving the plurality of light-emitting elements;
the moisture-resistant ring structure is disposed on the rectangular substrate so as to prevent moisture from entering the light-emitting element array, the pads, and the plurality of contact regions;
9. The light emitting device according to any one of items 1 to 8.
(Item 10)
The plurality of contact regions include a first contact region disposed between the light-emitting element array and the first side, a second contact region disposed between the light-emitting element array and the third side, and a third contact region disposed between the light-emitting element array and the fourth side.
10. The light emitting device according to item 9.
(Item 11)
a portion of the moisture-resistant wall that defines the shortest distance is disposed between the pad and the first contact region;
11. The light emitting device according to item 10.
(Item 12)
a second pad disposed on the rectangular substrate so as to be located between the first side and the light-emitting element array;
a portion of the moisture-resistant wall that defines the shortest distance is disposed between the pad and the second pad;
12. The light emitting device according to any one of items 1 to 11.
(Item 13)
a trace of contact of a part of a vapor deposition mask for forming the plurality of light-emitting elements between the moisture-resistant wall and the first edge;
13. The light emitting device according to any one of items 1 to 12.
(Item 14)
A photoreceptor;
a charging unit that charges the photosensitive member;
an exposure unit that exposes the surface of the photoreceptor to light so as to form an electrostatic latent image on the surface of the photoreceptor;
a developing unit that develops the electrostatic latent image,
The exposure unit includes the light-emitting device according to any one of items 1 to 13.
An image forming apparatus characterized by:
(Item 15)
A method for manufacturing a light emitting device, comprising:
the light emitting device comprises a rectangular substrate having first and second sides parallel to a first direction and third and fourth sides parallel to a second direction perpendicular to the first direction, a light emitting element array composed of a plurality of light emitting elements arranged on the rectangular substrate, a pad arranged on the rectangular substrate so as to be located between the first side and the light emitting element array, and a moisture-resistant ring structure arranged on the rectangular substrate so as to surround the light emitting element array and the pad, the moisture-resistant ring structure including a moisture-resistant wall arranged between the light emitting element array and the first side, the shortest distance between the light emitting element array and the moisture-resistant wall in the second direction being shorter than the distance between the light emitting element array and the moisture-resistant wall on an imaginary line parallel to the second direction and passing through the light emitting element array and the pad,
The manufacturing method includes a vapor deposition step of depositing a functional layer formation material on a material substrate having a plurality of rectangular substrate regions each of which is to become the rectangular substrate, using a vapor deposition mask;
each of the plurality of rectangular substrate regions of the material substrate has a contact allowance region between a portion of the moisture-resistant wall that defines the shortest distance and the first side;
the deposition mask includes a pattern portion having a plurality of protrusions that contact the contact-allowing regions in the plurality of rectangular substrate regions, and a plurality of openings;
In the vapor deposition step, the distance between the material substrate and the pattern portion is defined by the plurality of protrusions.
A method for manufacturing a light emitting device comprising the steps of:
(Item 16)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad;
the moisture-resistant wall is a part of the first moisture-resistant ring;
Item 16. The method for manufacturing a light-emitting device according to item 15.
(Item 17)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
Item 16. The method for manufacturing a light-emitting device according to item 15.
(Item 18)
the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
at least one of the first moisture-resistant ring and the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
Item 16. The method for manufacturing a light-emitting device according to item 15.
(Item 19)
the first moisture-resistant ring is disposed so as to surround the entire periphery of the light-emitting element array;
19. The method for manufacturing a light emitting device according to any one of items 16 to 18.

The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to clarify the scope of the invention.

1: Material substrate, 2: Light-emitting device, 3: Light-emitting element array, 4: Vapor deposition mask, 5: Opening, 6: Protrusion, 7: First moisture-resistant ring, 8: Pad, 9: Contact area, 10: Contact-permitted area, 11: Second moisture-resistant ring, 12: Insulating layer, 13: First electrode, 14: Organic film, 15: Second electrode, 16: Protective film, RS: Rectangular substrate, 70: Moisture-resistant ring structure, 71: Moisture-resistant wall, 72: Moisture-resistant wall, VSL: Virtual straight line, S1: First edge, S2: Second edge, S3: Third edge, S4: Fourth edge

Claims (18)

A light emitting device having a substrate having first and second sides parallel to a first direction and third and fourth sides parallel to a second direction perpendicular to the first direction,
a light-emitting element array having a plurality of light-emitting elements arranged on the substrate;
a pad disposed on the substrate so as to be located between the first side and the light-emitting element array;
a moisture-resistant ring structure disposed on the substrate so as to prevent moisture from entering the light-emitting element array and the pads;
the moisture-resistant ring structure includes a moisture-resistant wall disposed between the light-emitting element array and the first side,
the shortest distance between the light-emitting element array and the moisture-resistant wall in the second direction is shorter than the distance between the light-emitting element array and the moisture-resistant wall on an imaginary line that is parallel to the second direction and passes through the light-emitting element array and the pad;
A light-emitting device characterized by: the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad;
the moisture-resistant wall is a part of the first moisture-resistant ring;
2. The light emitting device according to claim 1. the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
2. The light emitting device according to claim 1. the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
at least one of the first moisture-resistant ring and the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
2. The light emitting device according to claim 1. the first moisture-resistant ring is disposed so as to surround the entire periphery of the light-emitting element array;
5. The light emitting device according to claim 2, wherein the light emitting device is a light emitting device. the first moisture-resistant ring is disposed so as to surround the light-emitting element array and the pads over the entire periphery;
the second moisture-proof ring is disposed so as to surround the entire periphery of the structure disposed inside the second moisture-proof ring;
5. The light emitting device according to claim 3 or 4. the minimum rectangle circumscribing the light-emitting element array has a dimension in the first direction greater than a dimension in the second direction;
5. The light emitting device according to claim 2, wherein the light emitting device is a light emitting device. Each of the plurality of light-emitting elements includes a plurality of functional layers made of an organic material.
5. The light emitting device according to claim 2, wherein the light emitting device is a light emitting device. a plurality of contact regions disposed on the substrate to receive signals or potentials for driving the plurality of light-emitting elements;
the moisture-resistant ring structure is disposed on the substrate so as to prevent moisture from entering the light-emitting element array, the pads, and the plurality of contact regions;
5. The light emitting device according to claim 2, wherein the light emitting device is a light emitting device. The plurality of contact regions include a first contact region disposed between the light-emitting element array and the first side, a second contact region disposed between the light-emitting element array and the third side, and a third contact region disposed between the light-emitting element array and the fourth side.
10. The light emitting device according to claim 9. a portion of the moisture-resistant wall that defines the shortest distance is disposed between the pad and the first contact region;
11. The light emitting device according to claim 10. a second pad disposed on the substrate so as to be located between the first side and the light-emitting element array;
a portion of the moisture resistant wall that defines the shortest distance is disposed between the pad and the second pad;
5. The light emitting device according to claim 2, wherein the light emitting device is a light emitting device. A photoreceptor;
a charging unit that charges the photosensitive member;
an exposure unit that exposes the surface of the photoreceptor to light so as to form an electrostatic latent image on the surface of the photoreceptor;
a developing unit that develops the electrostatic latent image,
The exposure unit includes the light-emitting device according to claim 1.
An image forming apparatus characterized by: A method for manufacturing a light emitting device, comprising:
the light-emitting device comprises a substrate having first and second sides parallel to a first direction and third and fourth sides parallel to a second direction perpendicular to the first direction, a light-emitting element array having a plurality of light-emitting elements arranged on the substrate, a pad arranged on the substrate so as to be located between the first side and the light-emitting element array, and a moisture-resistant ring structure arranged on the substrate so as to surround the light-emitting element array and the pad, the moisture-resistant ring structure including a moisture-resistant wall arranged between the light-emitting element array and the first side, and the shortest distance between the light-emitting element array and the moisture-resistant wall in the second direction is shorter than the distance between the light-emitting element array and the moisture-resistant wall on an imaginary line parallel to the second direction and passing through the light-emitting element array and the pad,
The manufacturing method includes a vapor deposition step of depositing a functional layer formation material on a material substrate having a plurality of substrate regions each to become the substrate, using a vapor deposition mask;
each of the plurality of substrate regions of the material substrate has a contact allowance region between a portion of the moisture-resistant wall that defines the shortest distance and the first edge;
the deposition mask includes a pattern portion having a plurality of protrusions that contact the contact-allowing regions in the plurality of substrate regions, and a plurality of openings;
In the vapor deposition step, the distance between the material substrate and the pattern portion is defined by the plurality of protrusions.
A method for manufacturing a light emitting device comprising the steps of: the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad;
the moisture-resistant wall is a part of the first moisture-resistant ring;
15. The method for manufacturing a light emitting device according to claim 14 . the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
15. The method for manufacturing a light emitting device according to claim 14 . the moisture-resistant ring structure includes a first moisture-resistant ring arranged to surround the light-emitting element array and the pad, and a second moisture-resistant ring arranged not to surround the light-emitting element array and the pad but to be surrounded by the first moisture-resistant ring;
the first moisture-resistant ring includes a portion that defines the distance between the light-emitting element array and the moisture-resistant wall on the imaginary straight line,
at least one of the first moisture-resistant ring and the second moisture-resistant ring includes a portion that defines the shortest distance between the light-emitting element array and the moisture-resistant wall;
15. The method for manufacturing a light emitting device according to claim 14 . the first moisture-resistant ring is disposed so as to surround the entire periphery of the light-emitting element array;
18. The method for manufacturing a light emitting device according to claim 15 .