JP2006221902A - LIGHT EMITTING DEVICE, MANUFACTURING METHOD THEREOF, IMAGE PRINTING DEVICE, AND IMAGE READING DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the utilization efficiency of light emitted from a light emitting element.
A light-emitting element 30 having a light-emitting layer 33 interposed between an anode 31 and a cathode 34 each having a light transmission property is disposed on the surface of a substrate 20. A base material 40 is disposed on the opposite side of the substrate 20 across the light emitting element 30. A depression 401 is formed at a position facing the light emitting layer 33 on the surface of the substrate 40. The concave surface 411 along the inner surface of the recess 401 in the reflective layer 41 formed so as to cover the surface of the base material 40 is a concave mirror that reflects the light emitted from the light emitting layer 33 to the side opposite to the substrate 20 to the substrate 20 side. Function as. The light transmitting member 42 is filled inside the recess 401 covered with the reflective layer 41.
[Selection] Figure 2

Description

  The present invention relates to a light emitting device using a light emitting material such as an organic EL (ElectroLuminescent) material, a manufacturing method thereof, and an image printing apparatus and an image reading device using the light emitting device.

This type of light emitting device is used in various electronic devices as an optical device such as a display device or an exposure device. For example, Patent Document 1 discloses an image printing apparatus that uses a light emitting device in which a large number of light emitting elements are arranged in an array as a head unit for forming an electrostatic latent image on an image carrier such as a photosensitive drum. For example, a printer) has been proposed.
JP 2000-77188 A (FIG. 1)

  By the way, the emitted light from each light emitting element diffuses as it progresses. Therefore, it is difficult to make a sufficient amount of light reach a specific area of the image carrier. If the luminance of the light emitting element is increased, a considerable amount of light can reach the surface of the image carrier. However, in this case, problems such as an increase in power consumption of the light emitting device and a shortened life of the light emitting element arise. obtain. Further, due to the diffusion of the emitted light from each light emitting element, it becomes difficult to selectively allow the emitted light from the light emitting element to reach only a narrow region corresponding to one pixel on the surface of the photosensitive member. This may be a factor that hinders high definition.

  In addition, a configuration in which a lens for condensing the light emitted from the light emitting element is disposed between the light emitting element and the image carrier is also proposed, but in this configuration also, the light emitted from the light emitting element is applied to the lens. Since there is no change in diffusing until it reaches, it is difficult to make a sufficient amount of light incident on the lens, and it cannot be a fundamental solution to a decrease in light utilization efficiency. Here, the image printing apparatus is illustrated as an example, and the problems of the prior art are mentioned. However, similar problems may occur in an image reading apparatus and a display apparatus using a light emitting device. This invention is made | formed in view of such a situation, and it aims at the solution of the subject of improving the utilization efficiency of the emitted light from a light emitting element.

In order to solve this problem, a light emitting device according to the present invention includes a first electrode and a second electrode, each having light transparency, a light emitting layer interposed between the first electrode and the second electrode, It is characterized by comprising a concave mirror disposed on the opposite side of the light emitting layer with one electrode interposed therebetween and having a concave surface facing the light emitting layer. In the present invention, the light emitting layer is a film body made of a material having a property of emitting light by the action of electrical energy. For example, a film body made of an organic EL material or an inorganic EL material, a layered light emitting diode element, or the like is included in the concept of the light emitting layer in the present invention.
In the present invention, the light emitted from the light emitting layer is reflected by the concave mirror, passes through the first electrode, the light emitting layer, and the second electrode, and is emitted from the light emitting device. The reflected light from the concave mirror has a reduced beam width compared to the reflected light from a flat mirror surface. Therefore, according to the present invention, it is possible to suppress the diffusion of the emitted light from the light emitting device and improve the utilization efficiency. For example, in a configuration in which the light-emitting device of the present invention is used as a head unit for forming a latent image on an image carrier such as a photosensitive drum, the light amount emitted from the light-emitting element reaches a predetermined region of the image carrier. It is possible to sufficiently maintain the ratio of the amount of light to be generated. In other words, since the amount of emitted light required for the light emitting layer to reach the desired amount of light to the image carrier can be reduced, the power consumed by the light emitting element can be reduced and the light emitting element over time can be reduced. Deterioration can be suppressed. Further, the light from the light emitting device can be made to reach a narrow area on the surface of the photosensitive member by narrowing the reflected light from the concave mirror. Therefore, for example, in an image printing apparatus that employs the light emitting device of the present invention as a head unit, each pixel can form a fine and high-resolution image.

  The concave mirror in the present invention is a reflector whose surface that reflects light from the light emitting layer is concave with respect to the light emitting element. The concave surface is typically a shape corresponding to the inner surface of the sphere, but the shape of the concave mirror in the present invention is not limited to this. For example, the concave surface of the concave mirror in the present invention may have a shape in which a part of the shape corresponding to the inner surface of the sphere is a flat surface (see FIG. 15) or a shape corresponding to the inner surface of the cylinder. (See FIG. 16). That is, the shape of the concave surface of the concave mirror in the present invention is determined so that the light from the light emitting layer reflected by the concave surface is narrowed compared with the reflected light on a simple plane (that is, the beam width is reduced). It is sufficient if it contains the processed parts. For example, assuming that parallel light in a direction perpendicular to the light emitting layer is incident on the concave surface, the shape of the concave surface of the concave mirror is selected so that the reflected light on the concave surface is narrowed down compared to the parallel light until reaching the concave surface. .

  In the desirable mode of the present invention, the substrate in which the dent was formed in the surface is further provided, and the surface of the reflective layer which covers the inner surface of the dent of the substrate is used as a concave mirror. According to this aspect, the shape of the concave surface of the concave mirror can be made substantially similar to the shape of the recess of the base material. Further, it is desirable that the reflective layer is a conductive film body that covers the depression and the other flat surface portion of the surface of the substrate, and the portion covering the flat surface portion is electrically connected to the first electrode. According to this configuration, since the reflective layer can function as a wiring together with the first electrode, the resistance value of the entire wiring can be reduced.

  In another aspect of the present invention, a light transmissive member is formed in the concave surface of the concave mirror by a material having optical transparency. According to this configuration, the mechanical strength of the light emitting element can be improved. However, the inside of the concave surface of the concave mirror may be a cavity. Note that the light transmitting member and the first electrode are preferably formed of a material having substantially the same refractive index. According to this configuration, it is possible to prevent total reflection of light at the boundary surface between the light transmission member and the first electrode.

  The light emitting device according to the present invention is used as an exposure device or a display device in various electronic apparatuses. For example, an image printing apparatus according to the present invention includes an image carrier, a charger that charges the image carrier, and a book that forms a latent image by irradiating the charged surface of the image carrier with light from the light emitting layer. The light-emitting device of the invention and a developing unit that forms a visible image on the image carrier by attaching toner to the latent image. In addition, an image reading apparatus according to the present invention includes the light emitting device of the present invention and a light receiving device that converts light emitted from the light emitting device and reflected by a reading object into an electrical signal. The light-emitting device according to the present invention is also used as a display device or lighting device for various electronic devices such as mobile phones and personal computers. For these electronic devices, a light-emitting device in which a plurality of light-emitting elements are arranged in a planar shape is particularly suitable.

  In a first method of manufacturing a light emitting device according to the present invention, a light transmitting member that protrudes from a plane parallel to the light emitting layer to the side opposite to the light emitting layer is provided with a light transmitting property at a position corresponding to the light emitting layer. And a second step of forming a concave mirror having a concave surface substantially similar to the surface of the light transmissive member by forming a film body having light reflectivity on the surface of the light transmissive member. Have. According to this method, the shape of the concave surface of the concave mirror is controlled by appropriately selecting the shape of the surface of the light transmitting member. Further, there is an advantage that an inexpensive method such as a droplet discharge method (ink jet method) can be adopted for forming the light transmitting member. But the method of producing a light transmissive member is not restricted to this. For example, a light transmitting member having a smooth curved surface can be formed by forming a film body made of a resin material in a region facing the light emitting element and rounding corners of the film body by heating. In the second manufacturing method, the timing at which the light emitting element is disposed is arbitrary. For example, the light transmitting member may be formed on the surface of the substrate on which the light emitting element has already been formed, or the light transmitting member may be formed on the back surface after forming the light transmitting member on the surface of the substrate.

  A second method for manufacturing a light emitting device according to the present invention includes a first step of forming a depression on the surface of a base material, and forming a film body that covers the inner surface of the depression with a light-reflective material. A second step of forming a concave mirror having a concave surface substantially similar to the inner surface of the substrate, and a third step of disposing the light emitting element at a position facing the concave mirror on the opposite side of the substrate with the film body interposed therebetween. According to this method, the shape of the concave surface of the concave mirror can be controlled by appropriately selecting the shape of the recess. In the second method, the step of forming the light transmissive member by filling the concave surface of the concave mirror with a light transmissive material may be further performed. In addition, the manufacturing method of the light-emitting device which concerns on this invention is not limited to the 1st and 2nd method illustrated above.

  Various embodiments of the present invention will be described with reference to the drawings. In the following drawings, the ratio of dimensions of each part is appropriately different from the actual one.

  FIG. 1 is a perspective view illustrating a partial configuration of an image printing apparatus using the light emitting device according to the present embodiment. As shown in the figure, the image printing apparatus includes a light emitting device 10, a converging lens array 15, and a photosensitive drum 110. The light emitting device 10 has a large number of light emitting elements arranged in an array. These light emitting elements selectively emit light according to an image to be printed on a recording material such as paper. The converging lens array 15 is disposed between the light emitting device 10 and the photosensitive drum 110. This converging lens array 15 includes a large number of gradient index lenses arranged in an array with each optical axis directed to the light emitting device 10. An example of such a converging lens array 15 is SLA (Selfoc Lens Array) available from Nippon Sheet Glass Co., Ltd. (Selfoc / SELFOC is a registered trademark of Nippon Sheet Glass Co., Ltd.). The light emitted from each light emitting element of the light emitting device 10 passes through each gradient index lens of the converging lens array 15 and reaches the surface of the photosensitive drum 110. By this exposure, a latent image corresponding to a desired image is formed on the surface of the photosensitive drum 110.

<Configuration of Light Emitting Device 10>
FIG. 2 is a cross-sectional view showing the configuration of the light emitting device 10, and FIG. 3 is a plan view showing the configuration of the surface of the light emitting device 10 facing the converging lens array 15. A sectional view taken along line II-II in FIG. 3 corresponds to FIG. As shown in FIG. 3, the light emitting device 10 has a plurality of light emitting elements 30 arranged in a two-row zigzag pattern on the surface of the substrate 20. However, the arrangement pattern of the light emitting elements 30 is not limited to this, and may be a single row or three or more rows, or may be arranged in another appropriate pattern. The light emitted from each light emitting element 30 passes through the substrate 20 and exits toward the converging lens array 15 (upward in FIG. 2). That is, the light emitting device 10 is a bottom emission type light emitting panel.

  The board | substrate 20 is a plate-shaped member which has a light transmittance, and is formed with materials, such as glass and a plastics. The surface of the substrate 20 on which the light emitting element 30 is disposed is covered with the base layer 21 over the entire surface. The underlayer 21 is a light transmissive film formed of silicon oxide or the like. As shown in FIG. 2, each light emitting element 30 has a configuration in which an anode 31, a hole injection layer 32, a light emitting layer 33, and a cathode 34 are laminated in this order from the substrate 20 side. The anode 31 and the cathode 34 are electrodes formed of a light-transmitting conductive material such as ITO (Indium Tin Oxide). The anode 31 is individually formed on the surface of the base layer 21 for each light emitting element 30. On the other hand, the cathode 34 is a common electrode for the plurality of light emitting elements 30.

  The light emitting layer 33 is a film body made of an organic EL material, and emits light according to electric energy applied by the anode 31 and the cathode 34. The light emitting layer 33 emits light in all directions. That is, the light emitted by the light emitting layer 33 not only goes directly to the substrate 20 side, but also travels from the light emitting layer 33 toward the side opposite to the substrate 20. The laminated structure of the light emitting element 30 is not limited to the configuration of FIG. For example, a configuration in which an electron injection layer or an electron transport layer is interposed between the cathode 34 and the light emitting layer 33, a configuration in which a hole transport layer is interposed between the anode 31 and the light emitting layer 33, or an appropriate A configuration in which an insulating film body is formed at any position is also employed. In other words, any structure in which the light emitting layer 33 is interposed between the anode 31 and the cathode 34 may be used.

  An insulating layer 22 is formed on the surface of the foundation layer 21. On the surface of the insulating layer 22, partition walls 23 that partition the light emitting elements 30 are formed. The hole injection layer 32 and the light emitting layer 33 are formed in a space surrounded by the partition wall 23 and having the anode 31 as a bottom surface. The material of the insulating layer 22 is, for example, silicon oxide or silicon nitride, and the material of the partition wall 23 is, for example, polyimide or acrylic. The cathode 34 is formed so as to cover the light emitting layer 33 and the partition wall 23.

  A substrate 40 is disposed on the surface of the cathode 34. The base material 40 is a light-transmitting film body that is formed so as to cover all the light emitting elements 30 arranged on the substrate 20, and is, for example, an ultraviolet curable or thermosetting material such as epoxy or acrylic. It is made of a functional resin material. The base material 40 seals the light emitting elements 30 in cooperation with the substrate 20, isolates these light emitting elements 30 from the outside air (moisture and oxygen), and suppresses deterioration thereof.

  A depression 401 is formed for each light emitting element 30 on the surface of the substrate 40 on the substrate 20 side. As shown in FIG. 3, when viewed from a direction perpendicular to the substrate 20, the periphery of the depression 401 has a shape (in this embodiment, a circle) including the light emitting layer 33 of the light emitting element 30. The inner surface (inner wall surface) of each recess 401 is a substantially hemispherical curved surface continuous over the entire surface.

  A reflective layer 41 is formed on the surface of the substrate 40 over the entire region including the inner surface of the recess 401. Since the depression 401 is formed at a position overlapping with the light emitting element 30, a surface (hereinafter referred to as “concave surface”) 411 of the reflective layer 41 that covers the inner surface of the depression 401 faces the light emitting element 30. The reflection layer 41 is a film body having light reflectivity and conductivity, and is formed of, for example, a single metal such as aluminum, silver, or platinum, or an alloy containing these metals as a main component. Therefore, the concave surface 411 of the reflective layer 41 functions as a concave mirror that reflects the light emitted from the light emitting element 30 to the opposite side of the substrate 20 to the substrate 20 side.

  The light transmitting member 42 is filled in the depression 401 of the base material 40 covered with the reflective layer 41. The light transmitting member 42 is a portion formed of a light-transmitting resin material such as epoxy or acrylic. More specifically, the light transmission member 42 is formed of a material having a refractive index substantially equal to that of the material constituting the cathode 34. A portion of the reflective layer 41 other than the concave surface 411 and the surface of the light transmitting member 42 are in contact with the surface of the cathode 34. In this configuration, the reflective layer 41 and the cathode 34 are electrically connected. Although ITO constituting the cathode 34 has a relatively high resistance value, the overall resistance value can be lowered by making the reflective layer 41 conductive to the cathode 34.

  The light emitted from the light emitting element 30 to the side opposite to the substrate 20 is transmitted through the cathode 34 and the light transmitting member 42 to reach the reflection layer 41, is reflected by the concave surface 411, and proceeds to the substrate 20 side. Since the refractive index of the cathode 34 and the light transmitting member 42 are substantially equal, light hardly reflects at the boundary between them. However, since the cathode 34 is formed extremely thin, total reflection at the boundary surface between the cathode 34 and the light transmitting member 42 may not be a problem. In this case, the refractive index of the cathode 34 and the refractive index of the light transmitting member 42 may be different.

  FIG. 4 is a cross-sectional view schematically showing how the light emitted from the light emitting element 30 is reflected by the concave surface 411. Although only the path of light emitted from the central portion of the light emitting element 30 is shown in the figure, light is actually emitted toward both the substrate 20 and the base material 40 from other portions. It is done. As shown in the figure, the light emitted from the light emitting element 30 to the side opposite to the substrate 20 travels toward the concave surface 411 of the reflective layer 41 while diffusing. The shape of the concave surface 411 is such that the reflected light on the concave surface 411 is narrower than the incident light on the concave surface 411 (that is, the light flux width of the reflected light on the concave surface 411 is smaller than the light flux width before reaching the concave surface 411. Selected). For example, in FIG. 4, light traveling while diffusing from the light emitting element 30 to the opposite side of the substrate 20 is in a direction perpendicular to the surface of the substrate 20 at the concave surface 411 of the reflective layer 41 (in other words, perpendicular to the light emitting layer 33). In the following, a case where light is reflected by DL (hereinafter referred to as “optical axis direction”) and transmitted through the substrate 20 as substantially parallel light Lr is illustrated.

  In other words, the shape of the concave surface 411 of the reflective layer 41 is such that when the parallel light traveling in the direction DL from the substrate 20 side reaches the concave surface 411, the reflected light at the concave surface 411 becomes the focused light. Selected. If the shape of the concave surface 411 is selected as described above, the diffusion of light toward the converging lens array 15 can be suppressed as compared with the configuration in which the light emitted from the light emitting element 30 is reflected on a simple plane. . Therefore, according to the present embodiment, it is possible to sufficiently ensure the ratio of the amount of light that passes through the converging lens array 15 and reaches the photosensitive drum 110 out of the total amount of light emitted from the light emitting element 30. In other words, it is possible to reduce the light amount of the light emitting element 30 that is necessary for reaching the desired light amount to the photosensitive drum 110, thereby reducing the power consumed by the light emitting element 30 and the light emitting element 30. The life of (especially the light emitting layer 33) can be extended.

<Method for Manufacturing Light-Emitting Device 10>
Next, a method for manufacturing the light emitting device 10 according to the present embodiment will be described. In the following, two types of manufacturing methods different in the method of creating the base material 40 and the light transmitting member 42 will be exemplified.

(1) First manufacturing method
As shown in FIG. 5, the base layer 21, the anode 31, the insulating layer 22, the partition wall 23, the hole injection layer 32, the light emitting layer 33 and the cathode 34 are formed on the surface of the substrate 20 in this order. Since these elements are formed by various known methods, detailed descriptions thereof are omitted.

  Next, as shown in FIG. 6, a light transmission member 42 is formed on the surface of the cathode 34. The light transmitting member 42 is formed by, for example, a droplet discharge method (ink jet method). That is, the droplets containing the resin material are ejected from the nozzles of the droplet ejection device to reach the position corresponding to the light emitting element 30 on the surface of the cathode 34, and the light transmitting member 42 is formed by curing this. The The surface of the light transmission member 42 formed by this method is a smooth curved surface.

  Subsequently, as shown in FIG. 7, the reflective layer 41 is formed so as to cover the entire surface of the cathode 34 on which the light transmitting member 42 is formed. The reflective layer 41 is formed by various film forming techniques such as sputtering and vacuum deposition. The concave surface 411 of the reflective layer 41 formed in this step is a curved surface that is substantially similar to the surface of the light transmitting member 42 (that is, a shape that is recessed on the side opposite to the light emitting element 30).

  Next, the base material 40 is formed so as to cover the entire surface of the reflective layer 41. The base material 40 is formed by applying a resin material such as epoxy or acrylic on the surface of the reflective layer 41 by a technique such as spin coating. The light emitting device 10 of FIG. 2 is completed through the above steps.

  A protective layer for protecting the light emitting element 30 from an external force may be attached on the surface of the substrate 40. This protective layer is a film-like member made of, for example, plastic. In this structure, you may utilize the base material 40 as an adhesive agent which fixes a protective layer on a board | substrate.

  According to the manufacturing method described above, the light transmitting member 42 having the concave surface 411 as a curved surface is formed by an inexpensive method such as a droplet discharge method. Therefore, for example, compared with a method in which the light transmitting member 42 is formed by a mold. Thus, the manufacturing cost can be kept low.

(2) Second manufacturing method
As shown in FIG. 8, a resist 52 is formed on the surface of a plate material 51 made of glass or plastic. An opening 521 that penetrates the resist 52 in the thickness direction is formed in a portion of the resist 52 corresponding to each light emitting element 30.

  Next, as shown in FIG. 9, a recess 511 is formed in the plate material 51 by etching the plate material 51 using an etching solution (for example, hydrofluoric acid). In this step, an etching solution is gradually introduced into the plate material 51 through the opening 521 of the resist 52. As a result, the portion around the opening 521 is gradually dissolved to form a hemispherical recess 511 centered on the opening 521.

  Thereafter, after the resist 52 is peeled off from the surface of the plate material 51, a portion of the plate material 51 having a predetermined thickness (a portion above the broken line L in FIG. 9) is shaved from the surface on the depression 511 side. The method of cutting the plate material 51 may be a method of mechanically grinding and polishing, or a method of chemically cutting such as etching. In the latter method, the plate material 51 is etched after the recess 511 is masked. Through the above steps, the base material 40 having the depression 401 (a part of the depression 511) formed on the surface as shown in FIG. 10 is completed.

  Next, as shown in FIG. 11, the reflective layer 41 is formed over the entire surface of the substrate 40 including the inner surface of the recess 401. The reflective layer 41 is formed by various film forming techniques such as sputtering and vacuum deposition. The concave surface 411 of the reflective layer 41 formed in this step is a curved surface along the inner surface of the recess 401 of the base material 40.

  Next, as shown in FIG. 12, a transparent material 53 is applied to the surface of the reflective layer 41. The transparent material 53 is a material that becomes the light transmitting member 42, and for example, a glass paste or a transparent ultraviolet curable or thermosetting resin material is used. Then, as shown in FIG. 12, the transparent material 53 is dent 401 by sliding a straight plate-shaped squeegee (leveler) 54 in contact with the surface of the substrate 40 where the dent 401 is formed. The excess portion overflowing from the depression 401 is removed. Thereafter, the light transmitting member 42 is formed as shown in FIG. 13 by curing the transparent material 53 filled in the depression 401. By leveling using the squeegee 54, the surface of the reflective layer 41 other than the concave surface 411 and the surface of the light transmitting member 42 are aligned in the same plane.

  On the other hand, a base layer 21, an anode 31, an insulating layer 22, a partition wall 23, a hole injection layer 32, a light emitting layer 33, and a cathode 34 are formed on the surface of the substrate 20 in this order (see FIG. 5). Then, the substrate 20 and the base material 40 are bonded together with an adhesive in a state where the cathode 34 of the substrate 20 and the reflective layer 41 and the light transmitting member 42 formed on the base material 40 face each other. The light emitting device 10 of FIG. 2 is completed through the above steps.

  In addition, the method for manufacturing the light emitting device 10 according to the present invention is not limited to the two types of methods exemplified above. For example, in the first manufacturing method, the light transmissive member 42 may be formed on the surface of the cathode 34 by a mold. In the second manufacturing method, the base material 40 having the depression 401 formed on the surface is used. You may form by a type | mold. Thus, according to the method using the mold, there is an advantage that the shape of the concave surface 411 can be accurately controlled.

<Modification>
Various modifications are added to the above embodiment. An example of a specific modification is as follows. In addition, you may combine each aspect shown below suitably.

(1) Modification 1
In the embodiment, the bottom emission type light emitting device 10 is illustrated, but the present invention is also applied to the top emission type light emitting device 10. FIG. 14 is a cross-sectional view (a cross-sectional view corresponding to FIG. 2) showing a configuration of a top emission type light emitting device 10 to which the present invention is applied. The converging lens array 15 and the photosensitive drum 110 are arranged in the upper part of the figure. As shown in FIG. 14, a base layer 21, an insulating layer 22, and a partition wall 23 are formed on the surface of the substrate 20, and a plurality of light emitting elements 30 are arranged. These light emitting elements 30 are sealed with a sealing material 36 made of a resin material such as epoxy or acrylic.

  On the other hand, the base material 40 is disposed on the surface of the substrate 20 opposite to the light emitting element 30. Similar to the above-described embodiment, a recess 401 is formed on the surface of the base material 40 at a position overlapping the light emitting element 30, and the reflective layer 41 is formed over the entire surface of the base material 40 including the recess 401. Also in this modification, the effect | action and effect similar to embodiment are show | played. In order to suppress the diffusion of light emitted from the light emitting element 30 and reaching the concave surface 411 of the reflective layer 41, a member thinner than the bottom emission type light emitting device 10 is used as the substrate 20.

  As described above, in the present invention, the substrate 20 on which the light emitting element 30 is disposed may be disposed on the opposite side of the base material 40 with the light emitting element 30 interposed therebetween as in the embodiment, or as in the present modification. In addition, the light emitting element 30 and the substrate 40 may be disposed. Further, in FIG. 14, the configuration in which the substrate 20 is interposed between the light emitting element 30 and the base material 40 is illustrated, but the surface of the base material 40 (more specifically, the portion other than the concave surface 411 in the reflective layer 41 and A configuration in which the light emitting element 30 is formed on the surface of the light transmitting member 42 is also employed. In this configuration, the substrate 20 is not necessary.

(2) Modification 2
In the embodiment, the configuration in which the light transmission member 42 is filled in the depression 401 of the base material 40 is illustrated, but the light transmission member 42 is not necessarily required. In other words, the space surrounded by the concave surface 411 of the reflective layer 41 and the cathode 34 may be a cavity. However, according to the configuration including the light transmitting member 42 as in the embodiment, the cathode 34 and the reflective layer 41 are prevented from being peeled off, and the mechanical strength of the light emitting element 30 is maintained at a high level. is there.

  Further, in the embodiment, the configuration in which the reflective layer 41 and the cathode 34 are electrically connected is illustrated, but the electrical connection between them is not necessarily required. Therefore, the reflective layer 41 may be formed of an insulating material.

  Furthermore, in the embodiment, the configuration in which the anode 31 is formed on the substrate 20 side and the cathode 34 is formed on the base material 40 side is illustrated, but conversely, the cathode 34 is formed on the substrate 20 side. A configuration in which the anode 31 is formed on the substrate 40 side is also employed. Therefore, the electrode that is electrically connected to the reflective layer 41 may be either the anode 31 or the cathode 34.

(3) Modification 3
The shape of the concave surface 411 of the reflective layer 41 is not limited to that described in the embodiment. For example, the shape of the inner surface of the concave surface 411 (or the depression 401) may be a shape in which the bottom of the substantially hemispherical shape is partially flat as shown in FIG. It is good also as a shape equivalent to the inner surface of the solid) whose cross section in FIG. According to these configurations, in addition to the same effects as the embodiment, there is an advantage that the substrate 40 can be thinned compared to the configuration of the embodiment in which the concave surface 411 is substantially hemispherical throughout. is there.

  In the embodiment, the configuration in which the planar shape of the light emitting element 30 and the concave surface 411 (the shape when viewed from the direction perpendicular to the substrate 20) is circular is illustrated, but for example, as shown in FIG. The planar shape of the element may be substantially rectangular. In this configuration, the concave surface 411 (or the depression 401) of the reflective layer 41 has a shape corresponding to the inner surface of the cylinder. Also in this configuration, the cross section viewed from the line II'-II 'in FIG. 16 is the same as that in the configuration in FIG. As described above, all the concave surfaces of the concave mirror in the present invention need not be curved surfaces. That is, it is sufficient that the concave surface 411 includes a surface that includes a portion that reflects the incident light so that the reflected light is narrowed more than the incident light from the light emitting layer. May be included.

(4) Modification 4
In the embodiment, the configuration in which one concave surface 411 (or the depression 401 of the base material 40) is formed for one light emitting element 30 is illustrated, but the correspondence relationship between the light emitting element 30 and the concave surface 411 is limited to this. Absent. For example, as illustrated in FIG. 17, a configuration in which one recess 401 or a concave surface 411 is formed for the plurality of light emitting elements 30 is also employed. In the configuration shown in the figure, one recess 401 is formed over the entire region of the substrate 40 facing the three light emitting elements 30. Therefore, in the reflective layer 41 formed on the surface of the substrate 40, one concave surface 411 facing the three light emitting elements 30 functions as a concave mirror. In particular, when the light emitting device 10 is used as a display device for displaying a color image composed of red, green, and blue, one for each group of three light emitting elements 30 corresponding to these three colors. A configuration in which the depression 401 and the concave surface 411 are formed is employed.

(5) Modification 5
In the embodiment, the light emitting layer 33 made of an organic EL material is exemplified, but the light emitting layer 33 may be formed of an inorganic EL material. Further, an LED (Light Emitting Diode) can be used as the light emitting layer 33. In other words, the light emitting layer in the present invention may be a film formed of a material that emits light by application of electric energy.

<Image printing device>
As shown in FIG. 1, the light emitting device 10 according to each of the above embodiments can be used as a line-type optical head for writing a latent image on an image carrier in an image printing apparatus using an electrophotographic system. Examples of the image printing apparatus include a printer, a printing part of a copying machine, and a printing part of a facsimile. FIG. 18 is a longitudinal sectional view showing an example of an image printing apparatus using the light emitting device 10 as a line type optical head. This image printing apparatus is a tandem type full-color image printing apparatus using a belt intermediate transfer body system.

  In this image printing apparatus, four organic EL array exposure heads 10K, 10C, 10M, and 10Y having the same configuration are replaced with four photosensitive drums (image carriers) 110K, 110C, 110M, and 110Y having the same configuration. The exposure positions are respectively arranged. The organic EL array exposure heads 10K, 10C, 10M, and 10Y are the light-emitting device 10 according to any one of the embodiments exemplified above.

  As shown in FIG. 18, this image printing apparatus is provided with a driving roller 121 and a driven roller 122. An endless intermediate transfer belt 120 is wound around these rollers 121 and 122, and an arrow indicates As shown, the periphery of the rollers 121 and 122 is rotated. Although not shown, tension applying means such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

  Around the intermediate transfer belt 120, four photosensitive drums 110K, 110C, 110M, and 110Y each having a photosensitive layer on the outer peripheral surface are arranged at a predetermined interval. The subscripts K, C, M, and Y mean that they are used to form black, cyan, magenta, and yellow visible images, respectively. The same applies to other members. The photosensitive drums 110K, 110C, 110M, and 110Y are rotationally driven in synchronization with the driving of the intermediate transfer belt 120.

  Around each photosensitive drum 110 (K, C, M, Y), a corona charger 111 (K, C, M, Y), an organic EL array exposure head 10 (K, C, M, Y), and Developers 114 (K, C, M, Y) are disposed. The corona charger 111 (K, C, M, Y) uniformly charges the outer peripheral surface of the corresponding photosensitive drum 110 (K, C, M, Y). The organic EL array exposure head 10 (K, C, M, Y) writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum. Each organic EL array exposure head 10 (K, C, M, Y) is arranged such that the arrangement direction of the plurality of light emitting elements 30 is along the bus (main scanning direction) of the photosensitive drum 110 (K, C, M, Y). Installed. The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of light emitting elements 30 described above. The developing device 114 (K, C, M, Y) forms a visible image, that is, a visible image on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

  The black, cyan, magenta, and yellow developed images formed by the four-color single-color image forming station are sequentially transferred onto the intermediate transfer belt 120 to be superimposed on the intermediate transfer belt 120. As a result, a full-color image is obtained. Four primary transfer corotrons (transfer devices) 112 (K, C, M, Y) are arranged inside the intermediate transfer belt 120. The primary transfer corotron 112 (K, C, M, Y) is disposed in the vicinity of the photosensitive drum 110 (K, C, M, Y), and the photosensitive drum 110 (K, C, M, Y). The electrostatic image is electrostatically attracted from the toner image to transfer the visible image to the intermediate transfer belt 120 passing between the photosensitive drum and the primary transfer corotron.

  A sheet 102 as an object on which an image is to be finally formed is fed one by one from the sheet feeding cassette 101 by the pickup roller 103, and between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. Sent to the nip. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 through the fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed in the upper part of the apparatus by a paper discharge roller pair 128.

Next, another embodiment of the image printing apparatus according to the present invention will be described.
FIG. 19 is a longitudinal sectional view of another image printing apparatus using the light emitting device 10 as a line type optical head. This image printing apparatus is a rotary development type full-color image printing apparatus using a belt intermediate transfer body system. In the image printing apparatus shown in FIG. 19, a corona charger 168, a rotary developing unit 161, an organic EL array exposure head 167, and an intermediate transfer belt 169 are provided around the photosensitive drum 165.

  The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. The organic EL array exposure head 167 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. The organic EL array exposure head 167 is the light emitting device 10 of each aspect exemplified above, and is installed such that the arrangement direction of the plurality of light emitting elements 30 is along the bus line (main scanning direction) of the photosensitive drum 165. The electrostatic latent image is written by irradiating the photosensitive drum 165 with light from these light emitting elements 30.

  The developing unit 161 is a drum in which four developing units 163Y, 163C, 163M, and 163K are arranged at an angular interval of 90 °, and can rotate counterclockwise about the shaft 161a. The developing units 163Y, 163C, 163M, and 163K supply yellow, cyan, magenta, and black toners to the photosensitive drum 165, respectively, and attach the toner as a developer to the electrostatic latent image, thereby the photosensitive drum 165. A visible image, that is, a visible image is formed.

  The endless intermediate transfer belt 169 is wound around a driving roller 170a, a driven roller 170b, a primary transfer roller 166, and a tension roller, and is rotated around these rollers in a direction indicated by an arrow. The primary transfer roller 166 transfers the visible image to the intermediate transfer belt 169 that passes between the photosensitive drum and the primary transfer roller 166 by electrostatically attracting the visible image from the photosensitive drum 165.

  Specifically, in the first rotation of the photosensitive drum 165, an electrostatic latent image for a yellow (Y) image is written by the exposure head 167, and a developed image of the same color is formed by the developing unit 163Y. The image is transferred to the transfer belt 169. Further, in the next rotation, an electrostatic latent image for a cyan (C) image is written by the exposure head 167, and a developed image of the same color is formed by the developing device 163C. The intermediate transfer is performed so as to overlap the yellow developed image. Transferred to the belt 169. Then, during the four rotations of the photosensitive drum 165, yellow, cyan, magenta, and black visible images are sequentially superimposed on the intermediate transfer belt 169. As a result, a full-color visible image is formed on the transfer belt 169. It is formed. When images are finally formed on both sides of a sheet as an object on which an image is to be formed, the same color images of the front and back surfaces are transferred to the intermediate transfer belt 169, and then the front and back surfaces are transferred to the intermediate transfer belt 169. A full-color visible image is obtained on the intermediate transfer belt 169 by transferring the visible image of the next color.

  The image printing apparatus is provided with a sheet conveyance path 174 through which a sheet is passed. The sheets are picked up one by one from the paper feed cassette 178 by the pick-up roller 179, advanced through the sheet transport path 174 by the transport roller, and between the intermediate transfer belt 169 and the secondary transfer roller 171 in contact with the drive roller 170a. Pass through the nip. The secondary transfer roller 171 transfers the developed image to one side of the sheet by electrostatically attracting a full-color developed image from the intermediate transfer belt 169 collectively. The secondary transfer roller 171 can be moved closer to and away from the intermediate transfer belt 169 by a clutch (not shown). The secondary transfer roller 171 is brought into contact with the intermediate transfer belt 169 when a full-color visible image is transferred onto the sheet, and is separated from the secondary transfer roller 171 while the visible image is superimposed on the intermediate transfer belt 169.

  The sheet on which the image has been transferred as described above is conveyed to the fixing device 172 and is passed between the heating roller 172a and the pressure roller 172b of the fixing device 172, whereby the visible image on the sheet is fixed. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. In the case of double-sided printing, after most of the sheet passes through the paper discharge roller pair 176, the paper discharge roller pair 176 is rotated in the reverse direction and introduced into the double-sided printing conveyance path 175 as indicated by an arrow G. The Then, the visible image is transferred to the other surface of the sheet by the secondary transfer roller 171, the fixing process is performed again by the fixing device 172, and then the sheet is discharged by the discharge roller pair 176.

  Since the image printing apparatus illustrated in FIGS. 18 and 19 uses the light emitting element 30 including the light emitting layer 33 as writing means (exposure means), the apparatus is smaller than when using a laser scanning optical system. Can be achieved. Note that the light-emitting device of the present invention can also be employed in an electrophotographic image printing apparatus other than those exemplified above. For example, the light emitting device according to the present invention can be applied to an image printing apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, and an image printing apparatus that forms a monochrome image. Is possible.

<Image reading device>
The light emitting device 10 of each aspect described above is used in an image reading apparatus as a line type optical head for irradiating light to a reading target. Examples of such an image reading apparatus include a scanner, a reading unit of a copying machine or a facsimile, a barcode reader, or a two-dimensional image code reader that reads a two-dimensional image code such as a QR code (registered trademark).

  FIG. 20 is a longitudinal sectional view showing an example of an image reading apparatus using the light emitting device 10 as a line type optical head. A flat platen glass 202 is provided on the upper part of the cabinet 201 of the image reading apparatus, and a document 203 to be read is placed on the platen glass 202 with its image surface facing downward. A platen cover (not shown) presses the document 203 toward the platen glass 202.

  Inside the cabinet 201, a high speed carriage 204 and a low speed carriage 205 are arranged so as to be movable in the horizontal direction. The high-speed carriage 204 is equipped with an organic EL array exposure head 206 (light emitting device 10 according to any one of the embodiments described above) that irradiates the original 203 and a reflecting mirror 207, and the low-speed carriage 205 has two reflecting mirrors. 208 and 209 are installed. These organic EL array exposure head 206 and reflecting mirrors 207, 208, and 209 extend in the direction perpendicular to the paper surface (main scanning direction) in FIG. The organic EL array exposure head 206 is installed so that the arrangement direction of the plurality of light emitting elements 30 is along the main scanning direction.

  A document reader 210 is disposed at a fixed position inside the cabinet 201. The document reader 210 includes an imaging lens 212 and a line sensor (light receiving device) 213 composed of a large number of photosensitive pixels (charge coupled devices). The line sensor 213 extends in the direction perpendicular to the paper surface (main scanning direction) in FIG. 20, and is installed so that the arrangement direction of the plurality of photosensitive pixels is along the main scanning direction.

  Light emitted from the organic EL array exposure head 206 (light emitting device 10) is transmitted through the platen glass 202 and reflected by the lower surface of the original 203. Reflected light from the original 203 is transmitted through the platen glass 202, reflected by the reflecting mirrors 207 to 209, and then imaged by the line sensor 213 by the imaging lens 212. The high-speed carriage 204 moves in the horizontal direction so that the entire surface of the original 203 is irradiated by the organic EL array exposure head 206, and the low-speed carriage 205 moves at half the speed of the high-speed carriage 204 to The length of the reflected light path reaching 213 is kept constant.

  The configuration of the image reading apparatus in which the light emitting device of the present invention is adopted is not limited to that shown in FIG. For example, the light receiving device may move together with the light emitting device 10 as the illumination device, or the reading target may be moved and read after both the light receiving device and the light emitting device 10 are fixed.

  Further, the electronic apparatus to which the light emitting device according to the present invention is applied is not limited to an image printing apparatus or an image reading apparatus. For example, the light emitting device of the present invention is also used as a display device or lighting device in various electronic devices. Such electronic devices include personal computers, mobile phones, personal digital assistants (PDAs), digital still cameras, televisions, video cameras, car navigation devices, pagers, electronic notebooks, electronic paper, calculators, word processors. , Workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices with touch panels, and the like. For these electronic devices, a light emitting device in which a plurality of light emitting elements are arranged in a planar shape is suitably employed.

1 is a perspective view illustrating a partial configuration of an image printing apparatus using a light emitting device according to the present invention. It is sectional drawing which shows the structure of a light-emitting device. It is a top view which shows the structure of the surface which opposes a converging lens array among light-emitting devices. It is sectional drawing which shows a mode that the emitted light from a light emitting layer reflects on the concave surface of a reflection layer. It is sectional drawing which shows a mode that the light emitting element was formed on the board | substrate by the 1st manufacturing method. It is sectional drawing which shows the process in which the light transmissive member is formed among the 1st manufacturing methods. It is sectional drawing which shows the process in which a reflection layer is formed among 1st manufacturing methods. It is sectional drawing which shows the process in which a resist is formed in the surface of a board | plate material among 2nd manufacturing methods. It is sectional drawing which shows the process in which a board | plate material is etched among 2nd manufacturing methods. It is sectional drawing which shows the shape of the base material created by the 2nd manufacturing method. It is sectional drawing which shows the process in which a reflection layer is formed in the surface of a base material among 2nd manufacturing methods. It is sectional drawing which shows the process with which the resin material is filled into the hollow of a base material among 2nd manufacturing methods. It is sectional drawing which shows a mode that the light transmissive member was formed in the hollow of the base material with the 2nd manufacturing method. 6 is a cross-sectional view illustrating a configuration of a top emission type light emitting device according to Modification 1. FIG. FIG. 11 is a cross-sectional view illustrating a configuration of a light emitting device according to Modification 3. It is a perspective view which shows the shape of the concave surface of a reflection layer among the other light-emitting devices which concern on the modification 3. It is sectional drawing which shows the structure of the light-emitting device which concerns on the modification 4. It is a longitudinal cross-sectional view which shows the structure of the image printing apparatus using the light-emitting device based on this invention. It is a longitudinal cross-sectional view which shows the structure of the other image printing apparatus using the light-emitting device based on this invention. It is a longitudinal cross-sectional view which shows the structure of the image reading apparatus using the light-emitting device based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light-emitting device, 15 ... Converging lens array, 110 ... Photosensitive drum, 20 ... Substrate, 21 ... Underlayer, 22 ... Insulating layer, 23 ... Partition, 30 ... Light-emitting element, 31 …… Anode, 32 …… Hole injection layer, 33 …… Light emitting layer, 34 …… Cathode, 40 …… Base material, 401 …… Dimple, 41 …… Reflective layer, 411 …… Concave surface, 42 …… Light transmission Element.

Claims (9)

A first electrode and a second electrode each having optical transparency;
A light emitting layer interposed between the first electrode and the second electrode;
A light emitting device comprising: a concave mirror disposed on the opposite side of the light emitting layer with the first electrode interposed therebetween, and having a concave surface facing the light emitting layer. Comprising a substrate with a depression formed on the surface;
The light emitting device according to claim 1, wherein the concave mirror is a surface of a reflective layer that covers an inner surface of a recess of the base material. The said reflection layer is an electroconductive film body which covers the said hollow and other plane part among the surfaces of the said base material, The part which covers the said plane part conduct | electrically_connects to a said 1st electrode. Light-emitting device. The light-emitting device according to any one of claims 1 to 3, further comprising a light-transmitting member formed in a concave surface of the concave mirror by a material having optical transparency. An image carrier;
A charger for charging the image carrier;
The light-emitting device according to any one of claims 1 to 4, wherein a latent image is formed by irradiating light from the light-emitting layer onto a charged surface of the image carrier.
An image printing apparatus comprising: a developing device that forms a visible image on the image carrier by attaching toner to the latent image. A light emitting device according to any one of claims 1 to 4,
An image reading device comprising: a light receiving device that converts light emitted from the light emitting device and reflected by a reading target into an electrical signal. A method of manufacturing a light emitting device comprising a first electrode and a second electrode, each having light transparency, and a light emitting layer interposed between both electrodes,
A first step of forming a light transmissive member projecting on the opposite side of the light emitting layer at a position corresponding to the light emitting layer with a material having light transmissivity;
A second step of forming a concave mirror having a concave surface substantially similar to the surface of the light transmissive member by forming a film body having light reflectivity on the surface of the light transmissive member. A method of manufacturing a light emitting device comprising a first electrode and a second electrode, each having light transparency, and a light emitting layer interposed between both electrodes,
A first step of forming a depression on the surface of the substrate;
A second step of forming a concave mirror having a concave surface substantially similar to the inner surface of the depression by forming a film covering the inner surface of the depression with a material having light reflectivity;
And a third step of disposing a light emitting element at a position facing the concave mirror on the opposite side of the base material with the film body interposed therebetween. The method for manufacturing a light emitting device according to claim 8, further comprising: filling a concave surface of the concave mirror with a light transmissive material.

Images