JP2006059544A - Electro-optical device and manufacturing method thereof, head for optical printer, optical printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optical device preferably used as a light source of an optical printer head with high rigidity of an electrical connection part with an external power source.
An electro-optical device includes a first substrate on which a light emitting element is formed, and a second substrate bonded to the first substrate for sealing the light emitting element. An auxiliary wiring 35 for electrically connecting the light emitting element 11 and the external power supply 40 is formed on the second substrate 14.
[Selection] Figure 1

Description

  The present invention relates to an electro-optical device including a light emitting element and a method for manufacturing the same, and more particularly to a technique preferably applied to a head of an optical printer.

  As a head of an optical printer, an LED head using a light emitting diode (LED) as a light source is generally known. Since the LED head is manufactured by mounting individual LED light sources one by one, the productivity is relatively low, and light emission unevenness is likely to occur due to slight deviation of the light source that occurs during mounting.

  On the other hand, a technique using an organic EL (electroluminescence) element as a light source of an optical printer head has been proposed (for example, see Patent Document 1). Printer heads using organic EL elements can be manufactured with relatively high productivity due to the ease of use of lithography technology, etc., and are suitable for improving drawing density (high definition) and miniaturization. ing.

When a light-emitting element such as the above-described organic EL element is used as a light source for an optical printer head, a lens array is disposed in the vicinity of the light-emitting element in order to extend the life of the light-emitting element and improve the light utilization efficiency There is known a technique for thinning (thinning) a substrate on which the substrate is formed (see, for example, Patent Documents 2 and 3).
JP-A-9-226172 JP 2003-260812 A JP 2002-184567 A

  In an electro-optical device including a light emitting element such as an organic EL element, a glass substrate is generally used as a substrate on which the light emitting element is formed. For this reason, when the substrate is thinned, the substrate is likely to be damaged particularly in electrical connection with an external power source. On the other hand, although technology for preventing damage to the substrate by making the element forming substrate made of resin has been proposed, resin has lower heat resistance than glass, and the processing process at the time of element formation is limited. Arise.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electro-optical device that is highly used as a light source of an optical printer head and a method of manufacturing the electro-optical device that have high electrical connection with an external power source. To do.
Another object of the present invention is to provide an optical printer head and an optical printer suitable for high definition and miniaturization.

  In order to achieve the above object, an electro-optical device of the present invention is an electro-optical device including a light-emitting element, and includes a first substrate on which the light-emitting element is formed, and the sealing for the light-emitting element. And a second substrate bonded to the first substrate, wherein the second substrate is formed with auxiliary wiring for electrically connecting the light emitting element and an external power source.

  In this electro-optical device, the light emitting element of the first substrate and the external power source are electrically connected via the auxiliary wiring formed on the second substrate. Since the direct connection portion with the external power source is the second substrate different from the first substrate on which the light emitting element is formed, it is easy to optimize the configuration relating to the electrical connection with the external power source. Therefore, this electro-optical device can easily increase the rigidity of the electrical connection portion with an external power source, and is preferably used as a light source of an optical printer head.

In the electro-optical device, the auxiliary wiring includes a first terminal electrically connected to the light emitting element inside the outer edge of the first substrate, and the external power source outside the outer edge of the first substrate. And a second terminal electrically connected.
In this case, it is preferable that the second substrate has an extending portion extending outward with respect to an outer edge of the first substrate, and the second terminal is formed in the extending portion.
In this electro-optical device, since the connection portion with the external power source is located outside the outer edge of the first substrate, there are few structural restrictions on the connection portion, and highly reliable electrical connection is possible.

In the above electro-optical device, the light emitting element is, for example, an organic EL element.
By using an organic EL element as the light emitting element, high definition of the element arrangement and miniaturization of the apparatus can be achieved.

In the electro-optical device, the first substrate may be processed to be thin.
By reducing the thickness of the first substrate, energy attenuation and light scattering when the light from the light emitting element passes through the first substrate is suppressed, and the utilization efficiency of light from the light emitting element is improved.
In this electro-optical device, even if the first substrate is thinned, the direct connection portion with the external power source is the second substrate different from the first substrate, so that the rigidity of the connection portion is reduced. It is easy to increase, and damage to the first substrate accompanying electrical connection with an external power source is prevented.

The electro-optical device may further include a third substrate bonded to the first substrate in order to improve the optical performance of the light emitting element.
In this case, the third substrate may include a lens disposed to face the light emitting element.
The use efficiency of light from the light emitting element is further improved by the third substrate.

In the electro-optical device, a recess is formed in the second substrate in a region of the first substrate facing the light emitting element formation region, and a desiccant is formed in the recess of the second substrate. May be arranged.
The desiccant suppresses an increase in humidity in the sealed space and extends the life of the light emitting element.

A head for an optical printer according to the present invention is characterized by using the above electro-optical device as a light source.
In this optical printer head, the above-described electro-optical device can be used as a light source to achieve high definition and miniaturization.

An optical printer according to the present invention includes the above-described optical printer head.
In this optical printer, high-definition and miniaturization can be achieved by providing the optical printer head.

  The method of manufacturing an electro-optical device according to the present invention includes a step of forming a light emitting element on a first substrate and a step of forming an auxiliary wiring for electrically connecting the light emitting element and an external power source on the second substrate. And bonding the first substrate and the second substrate and electrically connecting the light emitting element and the auxiliary wiring.

  In this electro-optical device manufacturing method, auxiliary wiring for electrically connecting the light emitting element and the external power source is formed on a second substrate different from the first substrate on which the light emitting element is formed. Therefore, as described above, the electro-optical device manufactured by this method can easily optimize the configuration related to the electrical connection with the external power source, and can easily increase the rigidity of the electrical connection portion with the external power source. .

  In the above manufacturing method, the second substrate may be a sealing substrate for sealing the light emitting element, for example.

In the above manufacturing method, the light emitting element is, for example, an organic EL element.
By using an organic EL element as the light emitting element, high definition of the element arrangement and miniaturization of the apparatus can be achieved.

The manufacturing method may further include a step of thinly processing the first substrate in a state where the first substrate and the second substrate are bonded to each other.
By reducing the thickness of the first substrate, an electro-optical device in which the utilization efficiency of light from the light emitting element is improved is manufactured.
In addition, even if the rigidity of the first substrate is reduced as the thickness is reduced, the direct connection portion with the external power source is the second substrate different from the first substrate, so that electrical connection with the external power source is possible. The damage of the 1st board | substrate accompanying with is prevented.

The manufacturing method may further include a step of bonding a third substrate that enhances the optical performance of the light emitting element to the first substrate.
In this case, the third substrate may include a lens disposed to face the light emitting element.
The use efficiency of light from the light emitting element is further improved by the third substrate.

The present invention will be described below with reference to the drawings. Note that in each drawing to be referred to, the scale may be different from the actual one in order to make the size recognizable on the drawing.
FIG. 1 is a diagram schematically showing an organic EL device according to an embodiment of the electro-optical device of the invention.

  In FIG. 1, an organic EL device 10 includes an element substrate 12 on which a plurality of organic EL elements 11 are formed, an optical substrate 13 bonded to the element substrate 12 in order to enhance the optical performance of the organic EL elements 11, and an organic EL In order to seal the element 11, the element substrate 12 and the sealing substrate 14 bonded together are configured.

  The organic EL element 11 has a structure in which a circuit element portion, a pixel electrode (anode), an organic functional layer including a light emitting layer, a counter electrode (cathode), and the like are sequentially laminated on a transparent element substrate 12 such as glass. In addition, the code | symbol 19 shown in FIG. 1 is a bank layer as a partition member provided in the boundary of a pixel. The bank layer 19 has a role of preventing adjacent materials from being mixed when the organic EL element 11 is formed.

  In the organic EL element 11, holes injected from the anode side and electrons injected from the cathode side recombine in the light emitting layer, and light emission via the excited state (light emission when the excited state is lost) Wake up. In addition, by appropriately selecting a material for forming the light emitting layer, emitted light having a predetermined chromaticity can be obtained. As a material for forming the light emitting layer, for example, a low molecular weight organic light emitting dye or a polymer light emitting material, that is, a light emitting material composed of various fluorescent materials or phosphorescent materials is used.

  Note that layers having specific functions such as a hole injection layer, a hole transport layer, and an electron transport layer are appropriately formed between the anode and the light-emitting layer and between the cathode and the light-emitting layer, respectively. In addition, electrical control for light emission is performed via a circuit element unit including an active element (transistor) and the like.

  Light emitted from the organic EL element 11 (light emitting layer) is emitted to the outside via the element substrate 12 and the optical substrate 13 (back emission type, bottom emission). In the back emission type, light emitted from the light emitting layer toward the element substrate 12 passes through the pixel electrode (anode) made of a transparent material as it is. On the other hand, the light of the light emitting layer emitted toward the side opposite to the element substrate 12 side is reflected by the counter electrode (cathode) and passes through the pixel electrode (anode). These lights are emitted from each organic EL element 11, pass through the element substrate 12, and enter the optical substrate 13.

  The optical substrate 13 is made of a transparent substrate such as glass, and has a microlens array structure in which a large number of microlenses 20 are formed on the surface facing the element substrate 12. And it is joined to the back surface (surface opposite to the element formation surface) of the element substrate 12 through a resin 21 (high refractive index resin in this example) having a predetermined optical performance. Each microlens 20 is formed in a hemispherical shape, and is aligned and arranged to face each of the organic EL elements 11 on the element substrate 12 on a one-to-one basis.

FIG. 2 is a schematic diagram for explaining the optical function of the optical substrate 13.
As shown in FIG. 2, the light from each organic EL element 11 that has passed through the element substrate 12 is partially refracted and condensed by the refracting surface (hemispherical surface) of the microlens 20. By this condensing, the utilization efficiency of light from each organic EL element 11 is improved.

  Here, the shape of the microlens 20, the material of the optical substrate 13, the material and thickness of the bonding resin 21, and the thickness of the element substrate 12 are determined as appropriate so that light crosstalk does not occur as much as possible. Crosstalk means that light emitted from each organic EL element 11 is emitted through a microlens 20 different from the corresponding microlens 20 on a one-to-one basis, resulting in a decrease in optical performance (such as light color mixing). Cheap. In order to prevent crosstalk, the element substrate 12 is preferably as thin as possible, for example, 100 μm or less (for example, 20 μm). Note that the technology described in Japanese Patent Laid-Open No. 2003-260812 can be used as the technology related to crosstalk prevention.

  Returning to FIG. 1, the sealing substrate 14 is bonded to the element formation surface of the element substrate 12 via the sealing resin 30, and forms a sealing space that is a sealed space for sealing the organic EL element 11. To do. And the penetration | invasion of the water and oxygen to the sealing space is prevented, and deterioration (oxidation etc.) of the organic EL element 11 is prevented. The sealed space is filled with a gas having a reduced oxygen concentration, for example, nitrogen gas.

  Further, the sealing substrate 14 has a recess 14a formed in a region of the element substrate 12 facing the formation region of the organic EL element 11 (element forming region 12a), and a desiccant 31 is disposed in the recess 14a. ing. The desiccant 31 suppresses an increase in the humidity of the sealed space and extends the life of the organic EL element 11.

  Furthermore, an auxiliary wiring 35 for electrically connecting the organic EL element 11 and the external power supply 40 is formed on the sealing substrate 14. Here, the external power supply 40 supplies electric signals for electric control related to electric power and light emission to each organic EL element 11 on the element substrate 12.

FIG. 3 is a partial plan view for explaining the auxiliary wiring 35.
As shown in FIG. 3 and FIG. 1 above, the element formation surface of the element substrate 12 is provided with a power supply wiring 41 for supplying power to each organic EL element in the element formation region 12a. The terminal 42 for connection is provided in the edge part. The terminal 42 of the power supply wiring 41 is disposed outside the element formation region 12a.

  The sealing substrate 14 has an extending portion 14 b that extends outward with respect to the outer edge 12 b of the element substrate 12. The auxiliary wiring 35 is formed on the sealing substrate 14 so as to extend inward and outward with respect to the outer edge 12 b of the element substrate 12. A terminal 35a is formed at one end of the auxiliary wiring 35 (inward of the outer edge 12b of the sealing substrate 14), and a terminal 35b is formed at the other end (outward of the outer edge 12b of the sealing substrate 14). Has been. That is, the terminal 35 b is formed in the extending portion 14 b of the sealing substrate 14 and is exposed without being covered with the element substrate 12 when not connected to the external power supply 40.

  The auxiliary wiring 35 on the sealing substrate 14 is electrically connected to the element substrate 12 inside the outer edge 12b of the element substrate 12, and is electrically connected to the external power source 40 outside the outer edge 12b of the element substrate 12. The That is, the terminal 35a of the auxiliary wiring 35 on the sealing substrate 14 and the terminal 42 on the element substrate 12 are connected inside the outer edge 12b of the element substrate 12, and the outer edge 12b of the element substrate 12 extends (extends). 14b), the terminal 35b of the auxiliary wiring 35 on the sealing substrate 14 and the terminal of the external power source 40 are connected. As a result, the organic EL element of the element substrate 12 and the external power supply 40 are electrically connected via the auxiliary wiring 35 formed on the sealing substrate 14. In addition, the code | symbol 45 shown in FIG. 1 is a conductive adhesive for electrical connection.

  Thus, in the organic EL device 10 of this example, the direct connection portion with the external power source 40 is the sealing substrate 14 different from the element substrate 12 on which the organic EL element 11 is formed. The rigidity of the electrical connection with the power source 40 is high. That is, in the organic EL device 10, the element substrate 12 is thinned (for example, a thickness of 100 μm or less) in order to increase the use efficiency of the emitted light of the organic EL element 11, but directly with the external power supply 40. Since the connecting portion is the sealing substrate 14 different from the element substrate 12, the rigidity of the connecting portion is high, and damage to the element substrate 12 due to the electrical connection with the external power source 40 is prevented.

  As the sealing substrate 14, an insulator such as glass is preferably used, and the shape such as the thickness is optimized so as to ensure sufficient rigidity for the electrical connection. Moreover, you may use what performed the insulation process to conductors, such as a metal, as the sealing substrate 14. FIG. For example, by using a metal material, it is possible to further increase the rigidity of the electrical connection portion with the external power source 40 while reducing the thickness of the sealing substrate 14.

Next, an example of a method for manufacturing the organic EL device 10 will be described.
FIG. 4 is a diagram for explaining an example of a method for manufacturing the organic EL device 10.
The manufacturing method of this example mainly includes a step of forming the organic EL element 11 on the element substrate 12 (FIG. 4A), and a step of bonding the element substrate 12 and the sealing substrate 14 (FIG. 4B). ), A step of thinning the element substrate 12 (FIG. 4C), and a step of bonding the element substrate 12 and the optical substrate 13 (FIG. 4D).

  In FIG. 4A, the organic EL element 11 is formed using a lithography method. When a low molecular material is used as a material for forming the light emitting layer, a vapor deposition method can be used for the material arrangement. Further, when a polymer material is used as a material for forming the light emitting layer, various coating methods such as a spin coating method, a printing method, and a liquid discharge method can be used for the material arrangement. In addition, the power supply wiring 41 and the terminal 42 are formed on the element substrate 12 at the same time as or before or after the formation of the organic EL element 11. The power supply wiring 41 and the terminal 42 may be formed using a lithography method or may be formed using a direct drawing method.

FIG. 5 is a diagram for explaining an example of a manufacturing method of the sealing substrate 14.
The sealing substrate 14 is formed by a step of forming the auxiliary wiring 35 on the base (FIG. 5A), a step of forming the recess 14a on the base (FIG. 5B), and the like. In addition, the desiccant 31 is loaded in the recessed part 14a.

  As described above, various materials can be applied as the base of the sealing substrate 14. In this example, a glass substrate OA-10 made by Nippon Electric Glass is used. As a material for forming the auxiliary wiring 35, a conductive metal material is used. The auxiliary wiring 35 may be formed by using a lithography method or may be formed by a direct drawing method. The recess 14a of the sealing substrate 14 may be chemically formed by etching or the like, or may be physically formed by machining or sandblasting. The size and depth of the recess 14a are determined according to the size of the element region on the element substrate 12 shown in FIG. 4A and the size (amount) of the desiccant to be loaded.

  Proceeding to FIG. 4B, the element substrate 12 and the sealing substrate 14 are bonded to each other by encapsulating a sealing resin 30 (such as a photocurable epoxy adhesive) on at least one of the element substrate 12 and the sealing substrate 14. It arrange | positions to this, and both board | substrates are bonded together and the sealing resin 30 is hardened. At this time, the desiccant 31 is loaded inside the recess 14 a of the sealing substrate 14. In this example, the outer diameter of the sealing substrate 14 is larger than that of the element substrate 12, and a part (extending portion 14 b) of the sealing substrate 14 protrudes outward with respect to the outer edge 12 b of the element substrate 12.

  In addition, when the element substrate 12 and the sealing substrate 14 are joined, the power supply wiring 41 on the element substrate 12 and the auxiliary wiring 35 on the sealing substrate 14 are simultaneously connected. That is, the terminal 42 of the power supply wiring 41 and the terminal 35 a of the auxiliary wiring 35 are electrically connected via the conductive adhesive 45. As the conductive adhesive 45, for example, a resin material containing conductive particles such as silver, gold, copper, platinum, and carbon particles is used.

  Further, when the element substrate 12 and the sealing substrate 14 are joined, the element substrate 12 and the sealing substrate 14 are aligned (aligned). For example, the alignment is performed based on observation results of marks formed on both substrates at the same time. An alignment mark may be formed at the time of wiring formation, or the wiring itself may be used as an alignment mark.

  Proceeding to FIG. 4C, thin processing of the element substrate 12 is performed in a state where the element substrate 12 and the sealing substrate 14 are bonded together. That is, after the element substrate 12 and the sealing substrate 14 are joined, the element substrate 12 is thinned by grinding and polishing the back surface (the surface opposite to the element formation surface) of the element substrate 12. As described above, the thickness of the element substrate 12 after the thin processing is determined so that the optical characteristics of the optical substrate 13 are good, and is, for example, 100 μm or less (for example, 20 μm).

FIG. 6 is a diagram for explaining an example of a method for manufacturing the optical substrate 13.
In this example, a plurality of microlenses are formed on the optical substrate 13 by wet etching. The optical substrate 13 includes a step of forming an etching protective film 48 (FIG. 6A), a step of patterning the protective film 48 (FIG. 6B), and a step of etching the base of the optical substrate 13 (FIG. 6C). )), A step of removing the protective film 48 (FIG. 6D) and the like. In addition, the formation method of a micro lens is not limited to the said method.

  In this example, a glass substrate OA-10 made by Nippon Electric Glass is used as the base of the optical substrate 13. The etching protection film 48 is a silicon nitride film, for example, and can be formed using a plasma CVD method. The patterning of the protective film 48 can be performed by a photolithography method including a dry etching process. For etching the substrate of the optical substrate 13, for example, a glass etching solution such as hydrofluoric acid is used. As the etching solution enters the opening of the patterned protective film 48 and isotropically proceeds, a plurality of hemispherical concave portions (microlenses 20) are formed on one surface of the optical substrate 13. . Note that the etching time, the processing temperature, and the like are appropriately controlled so that the concave portion (microlens 20) has a desired shape (such as a radius of curvature).

  Referring to FIG. 4D, the element substrate 12 and the optical substrate 13 are bonded to each other by disposing a resin 21 (high refractive index resin in this example) over the entire surface of at least one of the element substrate 12 and the optical substrate 13. Are bonded together to cure the resin 21. At this time, the resin 21 is filled in each hemispherical recess (microlens 20) formed in the optical substrate 13. The element substrate 12 and the optical substrate 13 are aligned (aligned) so that each organic EL element 11 of the element substrate 12 and each microlens 20 of the optical substrate 13 are arranged to face each other in a one-to-one relationship.

  Through the series of steps described above, the organic EL device 10 including the organic EL element 11 and the microlens 20 is completed. In this organic EL device 10, since the direct connection portion (auxiliary wiring 35) with the external power source is formed on the sealing substrate 14 different from the element substrate 12, the electrical connection portion with the external power source 40 is provided. High rigidity. Therefore, the present invention is preferably applied to various devices that can be miniaturized, such as a head for an optical printer.

FIG. 7 schematically shows a planar configuration example of the head for an optical printer.
The optical printer head 100 of this example includes a plurality of light emitting units 101. When the organic EL device 10 is used as a light source, the organic EL element 11 and the microlens 20 are disposed at each position of the plurality of light emitting units 101.
The optical printer includes the above-described optical printer head 100, a photosensitive drum, a transport mechanism, and the like. The technology described in Japanese Patent Application Laid-Open No. 2003-260812 can be used for the configuration of the optical printer.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

1 is a diagram schematically illustrating an organic EL device according to an embodiment of an electro-optical device of the invention. The schematic diagram for demonstrating the optical function of an optical board | substrate. The partial top view for demonstrating auxiliary wiring. The figure for demonstrating an example of the manufacturing method of an organic electroluminescent apparatus. The figure for demonstrating an example of the manufacturing method of a sealing substrate. The figure for demonstrating an example of the manufacturing method of an optical board | substrate. The figure which shows the example of a plane structure of the head for optical printers typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Organic EL device (electro-optical device), 11 ... Organic EL element (light emitting element), 12 ... Element substrate (first substrate), 12a ... Element formation region, 12b ... Outer edge, 13 ... Optical substrate (third substrate) 14 ... sealing substrate (second substrate), 14a ... concave portion, 14b ... extending portion, 20 ... microlens, 31 ... desiccant, 35 ... auxiliary wiring, 35a ... terminal (first terminal), 35b ... terminal ( (Second terminal), 40 ... external power supply, 41 ... power supply wiring, 100 ... optical printer head.

Claims (16)

An electro-optical device including a light emitting element,
A first substrate on which the light emitting element is formed;
A second substrate bonded to the first substrate,
An electro-optical device, wherein auxiliary wiring for electrically connecting the light emitting element and an external power source is formed on the second substrate.   The auxiliary wiring is electrically connected to the light emitting element inside the outer edge of the first substrate and electrically connected to the external power source outside the outer edge of the first substrate. The electro-optical device according to claim 1, further comprising a second terminal. The second substrate has an extending portion extending outward with respect to an outer edge of the first substrate;
The electro-optical device according to claim 2, wherein the second terminal is formed in the extending portion.   The electro-optical device according to claim 1, wherein the light emitting element is an organic EL element.   The electro-optical device according to claim 1, wherein the first substrate is processed to be thin.   The electro-optical device according to claim 1, further comprising a third substrate bonded to the first substrate in order to improve the optical performance of the light emitting element.   The electro-optical device according to claim 6, wherein the third substrate includes a lens disposed to face the light emitting element. The second substrate has a recess formed in a region facing the light emitting element formation region of the first substrate,
The electro-optical device according to claim 1, wherein a desiccant is disposed in the concave portion of the second substrate. An optical printer head,
9. An optical printer head using the electro-optical device according to claim 1 as a light source.   An optical printer comprising the optical printer head according to claim 9. A method for manufacturing an electro-optical device, comprising:
Forming a light emitting element on the first substrate;
Forming an auxiliary wiring for electrically connecting the light emitting element and an external power source on the second substrate;
A method of manufacturing an electro-optical device, comprising: bonding the first substrate and the second substrate and electrically connecting the light emitting element and the auxiliary wiring.   The method of manufacturing an electro-optical device according to claim 11, wherein the second substrate is a sealing substrate for sealing the light emitting element.   The method of manufacturing an electro-optical device according to claim 11, wherein the light emitting element is an organic EL element.   The electro-optical device according to claim 11, further comprising a step of thinly processing the first substrate in a state where the first substrate and the second substrate are bonded to each other. Manufacturing method.   The method of manufacturing an electro-optical device according to claim 11, further comprising a step of bonding a third substrate that enhances optical performance of the light emitting element to the first substrate. The method of manufacturing an electro-optical device according to claim 15, wherein the third substrate includes a lens disposed to face the light emitting element.

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