JP2014004752A - Light source device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve brightness of a light source device which has a surface light-emitting light source element as a light source.SOLUTION: A light source element 3 of a light source device 1 comprises a substrate 5, a recess part 7, a light reflection film 9, an optical waveguide 11, an organic EL element 13, and a microlens 15. The light reflection film 9 is formed on an inside wall of the recess part 7 formed on the substrate 5. The optical waveguide 11 having light transparency is embedded in the recess part 7 via the light reflection film 9. The organic EL element 13 is disposed on the light waveguide 11, and emits light in the light waveguide 11 via an upper face of the light waveguide 11. A part of the microlens 15 having light transparency is embedded in the recess part 7 via the light reflection film 9, and is in contact with the light waveguide 11 in the recess part 7. A curved surface having a lens function is formed on a portion of the microlens 15 disposed outside the recess part 7. Light emitted from the organic EL element 13 enters into the microlens 15 via the light waveguide 11 and goes out from the curved surface of the microlens 15.

Description

  The present invention relates to a light source device using a surface-emitting light emitting element as a light source, and an image forming apparatus using the same.

  In recent years, image forming apparatuses such as copiers, printers, facsimile machines, and multi-function machines have been required to have a function of printing high-resolution images in a short time. In order to print a high-resolution image, it is necessary that a light source for forming a latent image of the printed image on the photoconductor can be exposed at a narrow pitch in the main scanning direction. In addition, in order to achieve high speed by performing printing in a short time, it is necessary to form a latent image on the photoconductor in a short time, that is, to sufficiently increase the amount of light applied to the photoconductor to reduce the photosensitivity time. It is necessary to shorten it.

  In addition, the price of printing printers has been reduced, and both low price and high quality (high resolution) are required. As a method for meeting this demand, a high-density solid-state light source printer is considered promising. The high-density solid-state light source printer includes a solid-state light source and a photosensitive drum, and does not have a function of manipulating light.

As a typical light emitting element used for the light source, there is an LED (Light Emitting Diode).
However, in order to arrange the light emitting elements at a narrow pitch, it is necessary to make the light emitting elements small. Accordingly, the light emitting area of the light emitting element is necessarily reduced. For this reason, as the light emitting area decreases, the amount of light emitted by the light emitting element decreases, and it is difficult to achieve both the arrangement of the light emitting elements at a narrow pitch and the shortening of the exposure time.

Further, there is a limit to downsizing the LED light source, and there is a problem in realizing a high resolution (high accuracy) printer.
Further, a solid light source using an organic EL (Electro-Luminescence) light source instead of the LED light source is known (see, for example, Patent Documents 1 and 2).

JP 2003-205646 A JP 2007-147913 A

The organic EL element emits light in all directions of 180 °. However, this characteristic is that, in image forming equipment such as copiers, printers, facsimiles, and multi-function machines that require high brightness, the amount of irradiation with respect to the target is insufficient, and the viewpoint of light utilization efficiency Was not enough.
In a light source device using a surface-emitting light source element such as an LED or an organic EL element, it is required to improve luminance.

  A first object of the present invention is to improve the luminance of a light source device using a surface-emitting light source element as a light source.

  A second object of the present invention is to provide an image forming apparatus using such a light source device.

  The light source device according to the present invention includes a substrate, a recess formed in the substrate, a light reflecting film formed on an inner wall of the recess, and a light-transmitting material, and the light reflecting film is formed in the recess. A surface that is disposed on the optical waveguide so as not to cover a part of the region where the concave portion is formed, and that emits light into the optical waveguide via the upper surface of the optical waveguide A light emitting element, a light emitting port provided in a region where the surface light emitting element does not cover the recess, and a light exit for emitting the light emitted from the surface light emitting element out of the recess; and the light And a light source element having a microlens disposed at the emission port.

  In the light source device of the present invention, at least a part of the bottom surface of the concave portion is inclined or curved so that the depth of the concave portion is deeper on the light exit side, and due to the bottom shape of the concave portion, An example in which the light reflecting film and the bottom surface of the optical waveguide are inclined or curved so that light is easily reflected toward the light exit port in the optical waveguide can be given. However, the bottom surface of the recess, the light reflection film, and the bottom surface of the optical waveguide do not have to be inclined or curved in this way.

  In the light source device of the present invention, the light source element includes a convex portion for reflecting the light emitted from the surface-emitting light emitting element toward the light emitting port side in the concave portion below the light emitting port. You may make it.

  In the light source device of the present invention, the recess includes a recess-shaped recess in the bottom portion of the bottom surface of the light exit port, and the light reflecting film has a recess due to the shape of the recess in the recess. The light source device according to claim 1, comprising the light source device.

  In the light source device of the present invention, the concave portion includes a concave concave portion in the bottom portion of the bottom surface of the light exit port, and the light reflecting film is a concave portion due to the shape of the concave portion in the concave portion. May be provided. However, the bottom surface of the concave portion and the light reflecting film at a position below the light exit port may be flat or convex.

  In the light source device of the present invention, the microlens is partially embedded in the recess, is in contact with the optical waveguide in the recess, and has a curved surface having a lens function in a portion disposed outside the recess. An example can be given. However, in the light source device of the present invention, the shape and arrangement of the microlens are not limited to this.

  Furthermore, the interface between the optical waveguide material and the microlens material in the recess is inclined in a direction that widens on the light exit side or narrows on the light exit side with respect to the optical axis of the microlens. An example can be given. However, the interface may be parallel to the optical axis of the microlens.

  In the light source device of the present invention, the light source element includes a convex portion for reflecting the light emitted from the surface-emitting light emitting element toward the light emitting port side in the concave portion below the light emitting port. The microlens is partially embedded in the recess, is in contact with the optical waveguide in the recess, and has a curved surface having a lens function in a portion disposed outside the recess. The interface between the optical waveguide material and the microlens material is inclined in a direction spreading on the light exit side with respect to the optical axis of the microlens, and the microlens is refracted by the material of the optical waveguide. An example can be given in which it is made of a material having a refractive index substantially equal to the refractive index.

  In the light source device of the present invention, the recess includes a recess-shaped recess in the bottom portion of the bottom surface of the light exit port, and the light reflecting film has a recess due to the shape of the recess in the recess. The microlens has a curved surface having a lens function in a portion disposed outside the recess, part of which is embedded in the recess and is in contact with the optical waveguide in the recess. The interface between the optical waveguide material and the microlens material in the recess is inclined in a direction narrowing on the light exit side with respect to the optical axis of the microlens, and the microlens is a material of the optical waveguide. An example in which the material is made of a material having a refractive index larger than the refractive index of can be given.

  The light source element may further include a protective layer disposed on the surface-emitting light emitting element, and the protective layer may include a side wall around the microlens. However, the light source device of the present invention may not include the protective layer.

  In the light source device of the present invention, the light source element includes, as the microlens, a first microlens disposed at the light exit and a second microlens disposed above the microlens. May be. However, in the light source device of the present invention, the microlens may be configured by one microlens or may be formed by three or more microlenses.

  Furthermore, the light source element may include an aperture for preventing crosstalk between the first microlens and the second microlens. However, the light source device of the present invention may not include the aperture.

  The light source element further includes a cap layer made of a light transmissive material disposed on the surface-emitting light emitting element and the first microlens, and the second microlens is disposed on the upper surface of the cap layer. The cap layer may be formed so as to have a function of securing an optical focusing distance between the first microlens and the second microlens. However, the light source device of the present invention may not include the cap layer.

  Examples of the functions of the first microlens and the second microlens include a condensing optical system or a telecentric optical system. However, the functions of the first microlens and the second microlens are not limited to these optical systems.

  The light source element may include a crosstalk preventing layer having a side wall around the second microlens. However, the light source device of the present invention may not include the crosstalk prevention layer.

  In the light source device of the present invention, various types of surface-emitting light source elements can be used. For example, examples of the surface-emitting light source element include an organic EL element, a VCSEL (vertical cavity surface emitting laser), and an LEDA (LED array). However, in the light source device of the present invention, the surface-emitting light source element is not limited to these elements, and any surface-emitting light source element that emits light into the optical waveguide through the upper surface of the optical waveguide may be used. It may be of any type.

  In the light source device of the present invention, the light source element may include an antireflection film between the surface-emitting light emitting element and the optical waveguide. However, the light source device of the present invention may not include the antireflection film.

  The substrate may include a plurality of light source elements, and the microlenses of the light source elements may be arranged linearly or in a staggered pattern. However, the light source device of the present invention includes one in which the microlenses of the plurality of light source elements are not arranged linearly and in a staggered manner. In the light source device of the present invention, the number of light source elements formed on the substrate may be one.

  An image forming apparatus according to the present invention includes a light source device according to the present invention in which a plurality of the light source elements are provided on a substrate, and the microlenses of the light source elements are arranged linearly or in a staggered pattern, and exposure is performed by the light source device. A photosensitive drum.

  The light source device of the present invention includes an optical waveguide embedded in a recess through a light reflecting film, a surface-emitting light-emitting element that emits light into the optical waveguide through an upper surface of the optical waveguide, and a surface-emitting light-emitting element Is provided in a region that does not cover the recess, and has a light exit port for emitting the light emitted from the surface light emitting element to the outside of the recess, and a microlens arranged in the light exit port. Therefore, by having both the light guide plate structure, the light reflection structure, and the lens structure, it is possible to improve the luminance of the light source device using the surface light emitting element as the light source.

  An image forming apparatus of the present invention includes a light source device of the present invention in which a substrate includes a plurality of light source elements, and microlenses of the light source elements are arranged in a straight line, and a photosensitive drum exposed by the light source device. Therefore, the lens effect brought about by the array-shaped three-dimensional microfabrication in the light source device of the present invention improves the light condensing performance and realizes a high-precision and high-resolution image forming apparatus.

It is a schematic plan view for demonstrating one Example of a light source device. FIG. 2 is a conceptual cross-sectional view at the position A-A ′ in FIG. 1. FIG. 2 is a conceptual cross-sectional view at a position B-B ′ in FIG. 1. It is a schematic sectional drawing for explaining an example of an organic EL element. FIG. 4 is a conceptual diagram of an image forming apparatus using the light source device shown in FIGS. 1 to 3 as a solid light source. FIG. 4 is a schematic cross-sectional view for explaining an example of a manufacturing process of the light source device shown in FIGS. 1 to 3. It is a schematic sectional drawing for demonstrating the other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic plan view for demonstrating other Example of a light source device. FIG. 15 is a conceptual cross-sectional view at the position C-C ′ in FIG. 14. FIG. 16 is a conceptual cross-sectional view of an image forming apparatus using the light source device shown in FIGS. 14 and 15 as a solid light source. It is a schematic sectional drawing for demonstrating other Example of a light source device. It is a schematic sectional drawing for demonstrating other Example of a light source device.

  FIG. 1 is a schematic plan view for explaining one embodiment of a light source device. FIG. 2 is a conceptual cross-sectional view at the position A-A ′ in FIG. 1. FIG. 3 is a conceptual cross-sectional view taken along the B-B ′ position in FIG. 1.

  The light source device 1 includes a plurality of light source elements 3. The light source element 3 includes a substrate 5, a recess 7, a light reflecting film 9, an optical waveguide 11, an organic EL element 13, a light exit port 14, and a microlens 15. The plurality of light source elements 3 are formed on the same substrate 5.

  A recess 7 of each light source element 3 is formed on one surface of the substrate 5. The dimensions of the recess 7 are, for example, a depth of 1 to 5 μm (micrometer), a length of 100 μm to 10 mm (millimeter), and a width of 10 to 40 μm. The plurality of recesses 7 are arranged at a pitch P. The pitch P is, for example, about 10 μm when the printing density is applied to a 2500 dpi (dots per inch) printing machine, about 20 μm when applied to a 1200 dpi printing machine, and about 20 μm when applied to a 600 dpi printing machine. 40 μm.

  The light reflecting film 9 is formed on the inner wall of the recess 7. The light reflecting film 9 is made of, for example, an aluminum material. The film thickness of the light reflecting film 9 is, for example, 0.1 to 0.5 μm. Note that the material of the light reflecting film 9 is not limited to an aluminum material, and may be another metal material such as silver.

The optical waveguide 11 is embedded in the recess 7 via the light reflecting film 9. The optical waveguide 11 is made of a light transmissive material. The material of the optical waveguide 11 is, for example, a high refractive index material. Examples of the high refractive index material include Al ₂ O ₃ material (refractive index: Nd = 1.670), TiO ₂ material (refractive index: Nd = 2.403), and Nb ₂ O ₅ material (refractive index: Nd = 2.314), Ta ₂ O ₅ material (refractive index: Nd = 2.150), high refractive index resin material (refractive index: Nd = 1.65), sol-gel resin (refractive index: Nd = 1.60). ). The material of the optical waveguide 11 is not limited to these high refractive index materials, and any material having optical transparency may be used.

  The organic EL element 13 which is a surface light emitting element is disposed on the optical waveguide 11. The organic EL element 13 is disposed so as not to cover a part of the region where the recess 7 is formed. The organic EL element 13 emits light into the optical waveguide 11 through the upper surface of the optical waveguide 11. An antireflection film (not shown) is formed between the organic EL element 13 and the optical waveguide 11.

  The light exit 14 is provided in a region where the organic EL element 13 does not cover the recess 7. The light exit 14 is provided to emit the light emitted from the organic EL element 13 to the outside of the recess 7.

  The microlens 15 is provided at the light exit port 14. The microlens 15 is made of a light transmissive material. A part of the microlens 15 is embedded in the recess 7 through the light reflecting film 9 and is in contact with the optical waveguide 11 in the recess 7. A convex curved surface for realizing a light condensing function is formed in a portion of the microlens 15 disposed outside the concave portion 7. The curved surface of the microlens 15 may be a concave shape having a lens function. The curved surface of the microlens 15 may be an aspherical shape, and may be, for example, a refractive index distribution type curved surface or a refractive index sequential deflection type lens structure.

The material of the microlens 15 is, for example, the same material as the optical waveguide 11, a polymer resin material, a SiO ₂ material, or the like. In addition, the material of the microlens 15 should just be a material which has a light transmittance. The material of the microlens 15 can be selected with a high degree of freedom according to the optical design.

  The plurality of microlenses 15 are arranged on a straight line, for example. The pitch P of the microlenses 15 is the same as the pitch P of the recesses 7.

FIG. 4 is a schematic cross-sectional view for explaining an example of the organic EL element.
The organic EL element 13 includes an anode 13a, a hole injection layer 13c, a hole transport layer 13d, a light emitting layer 13e, an electron transport layer 13f, an electron injection layer 13g, and a cathode 13h. 1 to 3, the hole injection layer 13c, the hole transport layer 13d, the light emitting layer 13e, the electron transport layer 13f, the electron injection layer 13g, and the cathode 13h are integrally illustrated as the light emitting layer, the cathode 13b, and the like. .

  The anode 13a is a transparent conductive film, and is formed of, for example, ITO (indium tin oxide). The hole injection layer 13c, the hole transport layer 13d, the light emitting layer 13e, the electron transport layer 13f, and the electron injection layer 13g are formed of an organic material. The cathode 13h is made of aluminum, for example.

The anode 13 a is disposed on the optical waveguide 11. The anodes 13a are separated from each other by the adjacent light source elements 3. The anode 13a is insulated from the light reflecting film 9 by an antireflection film. However, the film for insulating the anode 13a and the light reflecting film 9 may be an insulating film different from the antireflection film.
The light emitting layer and the cathode 13b are disposed on the anode 13a and the substrate 5. The light emitting layer and the cathode 13b are separated from each other by the adjacent light source elements 3.

An antireflection film 16 is formed between the anode 13 a and the optical waveguide 11. The antireflection film 16 has a function of allowing the light emitted from the organic EL element 13 to easily enter the optical waveguide 11 efficiently. The antireflection film 16 is an antireflection film having a three-layer film structure using, for example, a SiO ₂ material and an Al ₂ O ₃ material. However, the configuration of the antireflection film 16 is not limited to this.

Note that the structure and arrangement of the organic EL element 13 are not limited to those shown in FIGS. 1 to 4, and may be any structure and arrangement that emits light into the optical waveguide 11 through the upper surface of the optical waveguide 11. Any structure and arrangement may be used.
For example, some or all of the plurality of layers of the film constituting the organic EL element 13 may be continuously formed between the adjacent light source elements 3.

  Light emitted from the organic EL element 13 enters the optical waveguide 11, is reflected by the light reflecting film 9, and propagates through the optical waveguide 11 made of a high refractive index material. That is, light propagates in the optical waveguide 11 made of a high refractive index material by the principle of an optical fiber while being reflected by the light reflecting film 9. The light propagated inside the optical waveguide 11 is emitted from the interface (end surface) with the material of the microlens 15.

  The light emitted from the optical waveguide 11 is emitted with a specific intensity distribution and angle component. The light that has entered the material of the microlens 15 is reflected by the light reflecting film 9 immediately below the material of the microlens 15 and is emitted upward from the opening. A convex curved surface of the microlens 15 is formed above the material of the microlens 15 and is focused upward by the lens effect.

  Since the light source device 1 includes the light source plate 3 including the light guide plate structure including the optical waveguide 11, the light reflection structure realized by the light reflection film 9, and the lens structure realized by the microlens 15, The luminance of a light source device using an organic EL element as a light source can be improved.

  Moreover, in the light source device 1, since the lens part which consists of the microlens 15 and the light emission part which consists of the organic EL element 13 are formed by integral structure, it is not necessary to prepare a lens separately. Furthermore, alignment adjustment is not necessary.

Further, by utilizing a surface-emitting light source (organic EL element 13), it is possible to improve the light quantity shortage that has been a problem of the organic EL element. Thereby, energy saving is realizable.
Moreover, the brightness | luminance which can be condensed can be increased by forming a reflective structure (light reflection film 9) by ternary fine processing.

  The light amount of the light source element 3 is proportional to the light emission area of the organic EL element 13. In order to further increase the amount of light, it is effective to increase the light emitting area of the organic EL element 13 by increasing the area of the upper surface of the optical waveguide 11 or adopting a concavo-convex structure on the upper surface of the optical waveguide 11. It is.

  Moreover, since the light source elements 3 can be finely arranged, the area of the light emitting source (microlens 15) can be reduced. Thereby, a pseudo point light source can be realized. In the case of a point light source, since the area of the light emitting point is small, the light collecting property is excellent. Thereby, the optical system for collecting light can be simplified.

  For example, when the light source area has a diameter of 100 μm, a larger lens is necessary. Further, as the diffusion angle increases, the lens power is required, and the lens becomes thicker. That is, a high-performance and expensive lens is required.

  On the other hand, when the light source area is 5 μm in diameter, it may be 5 μm of the lens. Even when the diffusion angle is large, if the lens is disposed near the light source, the power can be relatively small. That is, the lens may be thin.

  The light source device 1 has a function as a solid light source that replaces the LED. The light source device 1 realizes a compact, low-cost and high-quality (high accuracy) solid-state light source.

FIG. 5 is a conceptual diagram of an image forming apparatus using the light source device shown in FIGS. 1 to 3 as a solid light source.
The image forming apparatus includes a light source device 1 and a photosensitive drum 17 exposed by the light source device 1.

  The lens effect brought about by the array-shaped three-dimensional microfabrication in the light source device 1 improves the light condensing performance and realizes a high-precision and high-resolution image forming apparatus. Thereby, energy saving and highly accurate printing are realized.

  In addition, since the light source device 1 includes the microlens 15 having a condensing function, the light can be directly imaged on the photosensitive drum 17. Therefore, it is not necessary to separately prepare optical transmission means such as a fiber lens and a rod lens, which are conventionally required. As a result, the number of parts can be reduced and the price can be reduced.

  In addition, by integrating the organic EL element and the lens structure, a condensing lens is not required separately, and alignment adjustment is also unnecessary.

  The light source device 1 has a very compact structure including an optical system, and if manufactured by fine processing, the pitch between dots of printing can be finely processed to 10 μm or less. For example, high-precision printing (25.4 mm / 10 μm = about 2500 dpi) is possible. Furthermore, it is possible to finely process the pitch between dots to 5 μm or less, and ultrahigh-precision printing (25.4 mm / 5 μm = 5080 dpi) is possible. This accuracy is comparable to that of a photographic printer among currently available printers. The present invention can also contribute to the realization of a high-precision printing machine.

  FIG. 6 is a schematic cross-sectional view for explaining an example of a manufacturing process of the light source device 1 shown in FIGS. 1 to 3. The cross-sectional view in FIG. 6 corresponds to the cross section at the position A-A ′ and the cross section at the position B-B ′ in FIG. 1. The parenthesized numerals (1) to (7) in FIG. 6 correspond to the steps (1) to (7) described below. In addition, the manufacturing process of the light source device 1 is not limited to this.

(1) The material of the substrate 5 is, for example, quartz (glass material), polymethylpentene (resin material), or silicon. However, the process described below is basically a process that does not depend on the material of the substrate 5.

  The resist 19 is patterned on the surface of the substrate 5 using a photolithography technique. Etching technique is used to etch the substrate 5 using the resist 19 as a mask to form the recess 7. When the material of the substrate 5 is a glass material or a resin material, for example, RIE (reactive ion etching) dry etching is used. When the material of the substrate 5 is a silicon material, for example, wet etching or RIE dry etching is used. When wet etching is used, crystal anisotropic etching (alkali) is performed by etching the (100) plane of the substrate 5 made of silicon. The etching solution is, for example, an EDP solution, a KOH solution, or a TMAH solution. Etching conditions are the same as in a normal semiconductor process.

  Moreover, NIP (nanoimprint) technology can be used for the formation of the recess 7. A mold having a desired shape is prepared in advance. In the mold, a reverse structure having a desired uneven shape is formed in the mold. Using this mold, the mold shape is transferred onto the substrate with NIP resin. By using this method, it is possible to manufacture a shape such as a concavo-convex shape, a triangular shape, or an aspherical shape with a high degree of freedom. The size of the mold that can be manufactured is not particularly limited as long as the diameter is, for example, 8 inches or less. The pitch accuracy that can be produced can be controlled from several hundred nm (nanometers) to several mm as well as the fine machining accuracy. A desired shape can be formed by forming a shape with a mold on the substrate and then transferring the resin shape to the substrate using a dry etching method.

(2) A light reflecting film 9 made of, for example, an aluminum material is formed on the inner wall of the recess 7 by using a vacuum deposition method or a sputtering method. The resist 19 is left as it is.

(3) The resist 19 is stripped and removed. At this time, the aluminum material thin film formed on the surface of the resist 19 is also removed.

(4) The optical waveguide 11 is formed by embedding a high refractive index material in the recess 7 through the light reflecting film 9. For example, (a) Al ₂ O ₃ material (refractive index: Nd = 2.05) by vacuum deposition or sputtering, (b) High refractive index resin material by coating method (refractive index: Nd). = 1.65), (c) sol-gel material (refractive index: Nd = 1.60) thermally cured after application.
An antireflection film 16 (see FIG. 4) is formed on the light reflection film 9 and the optical waveguide 11. The antireflection film 16 may also be formed on the surface of the substrate 5.

(5) A pattern of a resist 21 having an opening at a position where the light emission port 14 (see FIG. 2) is to be formed is formed using a photolithography technique.

(6) Using a dry etching technique, a part of the optical waveguide 11 is etched using the resist 21 as a mask to form a light exit port 14 in the optical waveguide 11. The end face of the optical waveguide 11 located at the light exit 14 functions as an exit part.

(7) The organic EL element 13 is formed in a place other than the opening. As a method for forming the organic EL element 13, for example, a vacuum deposition method, a printing method (inkjet method), or a laser transfer method is used. Here, the anode 13 a of the organic EL element 13 is formed only on the optical waveguide 11 and on the light reflecting film 9 around the optical waveguide 11.

(8) As shown in FIGS. 2 and 3, a resin microlens 15 is manufactured so as to cover the opening (recessed portion) of the optical waveguide 11 and the organic EL element 13 around the opening. Thereby, the light source element 3 is formed and the manufacturing process of the light source device 1 is completed.

  In addition, the manufacturing method of the light source device 1 is not limited to the said manufacturing process. Moreover, the Example demonstrated below and the manufacturing method of the light source device of this invention are not limited to what follows the said manufacturing process.

  FIG. 7 is a schematic cross-sectional view for explaining another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 7 corresponds to the A-A ′ position in FIG. 1. In FIG. 7, parts having the same functions as those in FIGS. 1 to 3 are denoted by the same reference numerals.

  In the light source device 1 of this embodiment, the interface 11 a between the material of the optical waveguide 11 and the material of the microlens 15 in the recess 7 is an angle θ in a direction that widens on the opening side of the recess 7 with respect to the optical axis of the microlens 15. Just tilted. Other structures are the same as those of the embodiment shown in FIGS. Note that the refractive index of the material of the microlens 15 is larger than the refractive index of the material of the optical waveguide 11.

  The interface 11a is inclined with respect to the optical axis of the microlens 15 in the direction of spreading on the opening side of the recess 7, so that the interface 11a is parallel to the optical axis of the microlens 15 or the optical axis of the microlens 15. Therefore, the light use efficiency of the light emitted by the organic EL element 13 is improved as compared with the case where the light is inclined in the direction of narrowing on the opening side of the recess 7. The light emitted from the interface 11a into the material of the microlens 15 is reflected by the light reflecting film 9 at the lower part and emitted upward from the opening.

  FIG. 8 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 8 corresponds to the A-A ′ position in FIG. 1. In FIG. 8, parts having the same functions as those in FIG.

  This embodiment is different from the embodiment shown in FIG. 7 in that the concave portion is provided with a concave concave portion 7a having a concave shape in a portion directly below the material of the microlens 15 on the bottom surface. A concave shape is formed in the light reflecting film 9 due to the concave portion 7a in the concave portion. With this shape, the upward light collecting property is improved. In this embodiment, the use efficiency of light emitted from the organic EL element 13 is improved as compared with the embodiment shown in FIG.

  In the embodiment shown in FIG. 8, the interface 11 a may be parallel to the optical axis of the microlens 15.

  FIG. 9 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. 1 except that the protective layer 23 is formed. FIG. 9 corresponds to the A-A ′ position in FIG. 1. In FIG. 9, parts having the same functions as those in FIG. 8 are denoted by the same reference numerals.

  This embodiment is different from the embodiment shown in FIG. 8 in that it further includes a protective layer 23 disposed on the organic EL element 13. The protective layer 23 includes a side wall disposed so as to surround the microlens 15. The material of the protective layer 23 is, for example, a resin material, but is not limited to the resin material. Further, the side wall of the protective layer 23 around the microlens 15 does not necessarily need to surround the microlens 15.

The protective layer 23 functions as a protective film for the organic EL element 13.
Further, the protective layer 23 reflects upward the light that has caused the condensing leakage of the microlens 15 by the side wall disposed around the microlens 15. Thereby, in this embodiment, the utilization efficiency of the light emitted from the organic EL element 13 is improved as compared with the embodiment shown in FIG.

In the embodiment shown in FIG. 9, the interface 11 a may be parallel to the optical axis of the microlens 15.
Further, the light reflecting film 9 and the recess 7 directly under the material of the microlens 15 may be flat.

  FIG. 10 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. 1 except that the protective layer 23 is formed. FIG. 10 corresponds to the A-A ′ position in FIG. 1. In FIG. 10, parts having the same functions as those in FIG.

  In this embodiment, compared with the embodiment shown in FIG. 9, the interface 11 a is inclined with respect to the optical axis of the microlens 15 in a direction narrowing on the opening side of the recess 7. The microlens 15 is formed of a material having a refractive index larger than that of the material of the optical waveguide 11.

In this embodiment, since the interface 11a is inclined with respect to the optical axis of the microlens 15 in the direction of narrowing on the opening side of the recess 7, the light source element 3 is compared with the embodiment shown in FIG. Brightness is improved.
In the embodiment shown in FIG. 10, the protective layer 23 may not be formed.

  FIG. 11 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 11 corresponds to the A-A ′ position in FIG. 1. In FIG. 11, parts having the same functions as those in FIGS. 1 to 3 are denoted by the same reference numerals.

Compared with the embodiment shown in FIGS. 1 to 3, this embodiment reflects the light emitted from the organic EL element 13 into the concave portion 7 below the light emission port 14 toward the light emission port 14. The projection 25 is further provided. The material of the convex portion 25 is, for example, quartz material, aluminosilicate glass, polycondensation material (sol-gel material) having a skeleton of SiO ₂ , the same material as the substrate 5, the same material as the optical waveguide 11, or the like. The shape of the convex portion 25 is, for example, a triangular prism. When the same material as the substrate 5 is used as the material of the convex portion 25, for example, by using the NIP method, the shape of the mold manufactured in advance is transferred to form a convex shape on the bottom surface of the concave portion 7. The convex part 25 is formed by forming a reflecting film on the surface of the shape. Further, when the same material as that of the optical waveguide 11 is used as the material of the convex portion 25, a light transmissive material is embedded in the concave portion 7 to form the optical waveguide 11, and then a part of the optical waveguide 11 is patterned by an etching technique. Thus, the convex portion 25 is formed by manufacturing the convex shape.

Since this embodiment is provided with the convex portion 25, the luminance of the light source element 3 is improved as compared with the embodiments shown in FIGS.
In addition, the material and shape of the convex part 25 are not limited to this Example, What kind of material and shape will be sufficient if it is the material and shape which can reflect the light which the organic EL element radiate | emitted to the light exit 14 side. It may be a shape.

  FIG. 12 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 11 corresponds to the A-A ′ position in FIG. 1. In FIG. 12, the parts having the same functions as those in FIG.

In this embodiment, as compared with the embodiment shown in FIG. 11, the convex portion 25 is formed by the convex portion formed on the bottom surface of the concave portion 7 and the light reflecting film 9 formed on the surface of the convex portion. ing.
Thereby, the convex part 25 can be formed, without requiring the process and material for exclusive use for forming the convex part 25. FIG.

  In the embodiment shown in FIG. 11 or FIG. 12, the protective layer 23 may be formed similarly to the embodiment shown in FIG.

  FIG. 13 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 13 corresponds to the A-A ′ position in FIG. 1. In FIG. 13, parts having the same functions as those in FIG.

  In this embodiment, the microlens 15 is not embedded in the recess 7 as compared with the embodiment shown in FIG. The optical waveguide 11 is present in the recess 7 immediately below the microlens 15. The light exit 14 is provided at a position where the organic EL element 13 is not formed.

  A configuration in which the microlens 15 is not embedded in the concave portion 7 and the optical waveguide 11 is present in the concave portion 7 immediately below the microlens 15 can be applied to the above-described embodiments.

  FIG. 14 is a schematic plan view for explaining still another embodiment of the light source device. FIG. 15 is a conceptual cross-sectional view at the position C-C ′ in FIG. 14. In FIG. 14 and FIG. 15, the same reference numerals are given to portions that perform the same functions as in the above embodiment.

  The light source element 3 includes, as microlenses, a first microlens 15a disposed at the light exit port 14 and a second microlens 15b disposed above the microlens 15a. Two first microlenses 15 a are provided, and are arranged for each of the two reflecting surfaces of the convex portion 25. The material of the first microlens 15a is, for example, a resin having optical transparency. The shape of the first microlens 15a is, for example, an elliptic cylinder. However, the number, material, and shape of the first microlenses 15a are not limited to these.

  An embedding material 27 made of a light-transmitting material is embedded in the recess 7 immediately below the first microlens 15a. The embedding material 27 is in contact with the first microlens 15 a, the convex portion 25, and the optical waveguide 11. The embedding material 27 is made of the same material (high refractive index material) as the optical waveguide 11 or a material different from the optical waveguide 11 (low refractive index material). However, the material of the embedding material 27 may be any material as long as it has optical transparency. The embedding material 27 may be formed at a cavity (gas layer).

  A cap layer 29 made of a light transmissive material is formed on the organic EL element 13 and the first microlens 15a. The cap layer 29 is made of, for example, seal glass. However, the material of the cap layer 29 is not limited as long as it has light transmissivity.

  A second microlens 15 b is disposed on the cap layer 29. The material of the second microlens 15b is, for example, a resin having optical transparency. However, the material of the second microlens 15b is not limited to this.

  The cap layer 29 has a function of ensuring an optical condensing interval between the first microlens 15a and the second microlens 15b. The cap layer 29 also functions as a protective layer for the organic EL element 13.

  An aperture 31 for preventing crosstalk between the adjacent light source elements 3 is provided between the first microlens 15a and the second microlens 15b. In this embodiment, the aperture 31 is disposed on the upper surface of the cap layer 29. However, the aperture 31 may be disposed at any position as long as it is a position between the first microlens 15a and the second microlens 15b and can prevent crosstalk.

On the cap layer 29, a crosstalk preventing layer 33 having a side wall 33a around the second microlens 15b is disposed. The material of the crosstalk preventing layer 33 is, for example, a metal material such as chromium or aluminum, a resin material, a polycondensation material (sol-gel material) having a SiO ₂ skeleton. Although the formation method of the crosstalk prevention layer 33 is not specifically limited, When a resin material or a sol-gel material is used as a material of the crosstalk prevention layer 33, the crosstalk prevention layer 33 can be formed by NIP method. However, the material of the crosstalk preventing layer 33 may be any material as long as it can prevent crosstalk between adjacent light source elements 3. Further, the side wall 33a of the crosstalk preventing layer 33 only needs to be disposed at a position where crosstalk between adjacent light source elements 3 can be prevented, and does not necessarily surround the second microlens 15b. Good. The formation method of the crosstalk prevention layer 33 is not limited to the NIP method.

  The function of the 1st micro lens 15a and the 2nd micro lens 15b comprises a telecentric optical system, for example. However, the functions of the first microlens 15a and the second microlens 15b are not limited to the telecentric optical system, and may be other optical systems such as a condensing optical system.

FIG. 16 is a conceptual diagram of an image forming apparatus using the light source device shown in FIGS. 14 and 15 as a solid light source.
When the first microlens 15a and the second microlens 15b constitute a telecentric optical system, the light emitted from the optical waveguide 11 and reflected by the convex portion 25 travels upward as parallel light. The light emitted from the second microlens 15 b is collected on the photosensitive drum 17.

  Since the light source device 1 of this embodiment employs two layers of lenses 15a and 15b in the light source element 3, a bright optical system can be formed without a decrease in luminance. Furthermore, since a semiconductor process can be employed as a manufacturing process and an integrated pairing mechanism is employed, optical accuracy and manufacturing reproducibility are very high.

  Further, between the adjacent light source elements 3, the light emitted from the light source element 3 is partitioned by the aperture 31 and the side wall 33a of the crosstalk preventing layer 33, so that crosstalk (stray light of light from the adjacent light source element 3). The light from a pure light source can be extracted. Thereby, high-precision printing can be realized.

  In addition, the structure provided with the 1st micro lens 15a and the 2nd micro lens 15b as a micro lens, and also provided with the cap layer 31 and the crosstalk prevention layer 33 is applicable to each above-mentioned Example.

  FIG. 17 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 17 corresponds to the C-C ′ position in FIG. 14. In FIG. 17, parts having the same functions as those in FIGS. 14 and 15 are denoted by the same reference numerals.

  In this embodiment, as compared with the embodiment shown in FIGS. 14 and 15, the bottom surface of the recess 7 is inclined so that the depth of the recess 7 is deeper on the light emission port 14 side. The bottom surfaces of the light reflecting film 9 and the optical waveguide 11 are inclined so that light is easily reflected in the optical waveguide 7 toward the light exit port 14 due to the bottom surface shape of the recess 7. Thereby, the luminance of the light source element 3 is improved.

  The position where the inclination is formed may be a part of the formation region of the recess 7. Further, the inclination angles of the bottom surface of the recess 7, the bottom surface of the light reflection film 9 and the optical waveguide 11 with respect to the top surface of the substrate 5 are arbitrary.

  FIG. 18 is a schematic cross-sectional view for explaining still another embodiment of the light source device. The plan view of this embodiment is the same as FIG. FIG. 18 corresponds to the C-C ′ position in FIG. 14. In FIG. 18, parts having the same functions as those in FIGS. 14 and 15 are denoted by the same reference numerals.

  In this embodiment, as compared with the embodiment shown in FIGS. 14 and 15, the bottom surface of the recess 7 is curved so that the depth of the recess 7 is deeper on the light emission port 14 side. The bottom surfaces of the light reflecting film 9 and the optical waveguide 11 are curved so that the light is easily reflected in the optical waveguide 7 toward the light exit port 14 due to the bottom surface shape of the recess 7. Thereby, the luminance of the light source element 3 is improved.

  The position where the curved portion is formed may be a part of the formation region of the recess 7. Further, the shapes of the curved surfaces of the bottom surface of the recess 7, the light reflecting film 9 and the bottom surface of the optical waveguide 11 are arbitrary. For example, the interface between the light reflecting film 9 and the bottom surface of the optical waveguide 11 is located on a circular arc of a cylinder having the central axis of the convex portion 25 so that light gathers toward the central axis of the convex portion 25 that is a triangular prism. An example can be given. Thereby, the brightness | luminance of the light source element 3 improves more.

  The configuration in which the bottom surface of the recess 7, the light reflecting film 9, and the bottom surface of the optical waveguide 11 are inclined or curved as described above can be applied to the above-described embodiments.

  In each of the above-described embodiments, an example in which the antireflection film 16 is formed between the organic EL element 13 and the optical waveguide 11 has been described. Although the antireflection film 16 may not be formed, the transmittance of light from the organic EL element 13 to the optical waveguide 11 is improved by forming the antireflection film 16.

The results of studying the antireflection film will be described.
Al ₂ O ₃ and SiO ₂ were examined as the optical waveguide medium. The incident angle was calculated at 0 degree. In order to obtain the average transmittance of visible light, the transmittance of light having a wavelength of 350 nm to 850 nm was obtained, and the center design wavelength was calculated at 550 nm.

For an optical waveguide whose medium is Al ₂ O ₃ , Ta ₂ O ₅ (film thickness: 15.26 nm) / SiO ₂ (film thickness: 18.13 nm) / Ta ₂ O ₅ (film thickness: in order from the optical waveguide side) An antireflection film having a three-layer film structure of 8.36 nm) was set. An organic EL element anode (ITO) was placed on the antireflection film. The refractive index of each _{material, Al 2 O 3: 1.67,} Ta 2 O 5: 2.14, SiO 2: 1.46, ITO: 2.05.

When no antireflection film was disposed (ITO / Al ₂ O ₃ laminate structure), the average transmittance of visible light was 99.0%.
When an antireflection film was disposed (laminated structure of ITO / Ta ₂ O ₅ / SiO ₂ / Ta ₂ O ₅ / Al ₂ O ₃ ), the average visible light transmittance was 99.7%.
By arranging the antireflection film, the average visible light transmittance was improved by 0.7%.

Further, an antireflection film of Al ₂ O ₃ (film thickness: 64.79 nm) was set for the optical waveguide whose medium is SiO ₂ . An organic EL element anode (ITO) was placed on the antireflection film. The refractive index of each material is as described above.

When no antireflection film was disposed (ITO / SiO ₂ laminate structure), the average visible light transmittance was 97.5%.
When an antireflection film was disposed (laminated structure of ITO / Al ₂ O ₃ / SiO ₂ ), the average visible light transmittance was 99.2%.
By arranging the antireflection film, the average visible light transmittance was improved by 1.7%.

  Thus, by forming the antireflection film between the organic EL element and the optical waveguide, the light transmittance from the organic EL element to the optical waveguide is improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the materials, numerical values, arrangements, and the like shown in the embodiments are examples, and are described in the claims. Various modifications are possible within the scope of the present invention.

  For example, in the above embodiment, an organic EL element is used as the surface-emitting light source element. However, in the light source device of the present invention, the surface-emitting light source element may be a surface-emitting light source element having another structure. For example, VCSEL or LEDA may be arranged instead of the organic EL element. However, in the light source device of the present invention, the surface-emitting light source element is not limited to these elements, and any surface-emitting light source element that emits light into the optical waveguide through the upper surface of the optical waveguide may be used. It may be of any type.

DESCRIPTION OF SYMBOLS 1 Light source device 3 Light source element 5 Substrate 7 Concave part 7a Concave part in concave part 9 Light reflecting film 11 Optical waveguide 11a Interface 13 Organic EL element 14 Light exit port 15 Microlens 16 Antireflection film 17 Photosensitive drum 23 Protective layer 25 Convex part 29 Cap Layer 31 Aperture 33 Crosstalk prevention layer 33a Side wall

Claims (18)

A substrate,
A recess formed in the substrate;
A light reflecting film formed on the inner wall of the recess,
An optical waveguide made of a material having optical transparency, embedded in the recess through the light reflecting film,
A surface-emitting light-emitting element that is disposed on the optical waveguide so as not to cover a part of the region where the recess is formed, and emits light into the optical waveguide through the upper surface of the optical waveguide;
A light-emitting port for emitting the light emitted from the surface-emitting light-emitting element to the outside of the recess, provided in a region where the surface-emitting light-emitting element does not cover the recess;
A light source device comprising a light source element having a microlens disposed at the light exit port.   At least a part of the bottom surface of the concave portion is inclined or curved so that the depth of the concave portion is deeper on the light emitting port side, and the light reflecting film and the optical waveguide are caused by the bottom shape of the concave portion. The light source device according to claim 1, wherein the bottom surface of the light source is inclined or curved so that light is easily reflected toward the light exit port in the optical waveguide.   The said light source element is provided with the convex part for reflecting the light which the said surface emitting light emitting element emitted to the said light-projection opening side in the said recessed part under the said light-projection opening. The light source device described. The concave portion is provided with a concave concave portion in the lower portion of the bottom surface of the light exit port,
The light source device according to claim 1, wherein the light reflecting film includes a recess due to a shape of the recess in the recess.   5. The microlens has a curved surface having a lens function in a portion embedded in the recess, in contact with the optical waveguide in the recess, and in a portion disposed outside the recess. The light source device according to any one of the above.   The interface between the optical waveguide material and the microlens material in the recess is inclined with respect to the optical axis of the microlens in a direction that widens on the light exit side or a direction that narrows on the light exit side. Item 6. The light source device according to Item 5. The light source element includes a convex portion for reflecting the light emitted from the surface-emitting light emitting element toward the light exit port in the recess below the light exit port,
The microlens has a curved surface having a lens function in a portion disposed outside the recess, part of which is embedded in the recess and is in contact with the optical waveguide in the recess.
The interface between the optical waveguide material and the microlens material in the recess is inclined in a direction spreading on the light exit side with respect to the optical axis of the microlens,
The light source device according to claim 1, wherein the microlens is made of a material having a refractive index substantially equal to a refractive index of a material of the optical waveguide. The concave portion is provided with a concave concave portion in the lower portion of the bottom surface of the light exit port,
The light reflecting film has a recess due to the shape of the recess in the recess,
The microlens has a curved surface having a lens function in a portion disposed outside the recess, part of which is embedded in the recess and is in contact with the optical waveguide in the recess.
The interface between the optical waveguide material and the microlens material in the recess is inclined in a direction narrowing on the light exit side with respect to the optical axis of the microlens,
The light source device according to claim 1, wherein the microlens is formed of a material having a refractive index larger than that of the material of the optical waveguide. The light source element further includes a protective layer disposed on the surface light emitting element.
The light source device according to claim 1, wherein the protective layer includes a side wall around the microlens.   The said light source element is provided with the 1st micro lens arrange | positioned at the said light exit as the said micro lens, and the 2nd micro lens arrange | positioned above the said micro lens. The light source device according to item.   The light source device according to claim 10, wherein the light source element includes an aperture for preventing crosstalk between the first microlens and the second microlens. The light source element further includes a cap layer made of a light transmissive material disposed on the surface-emitting light emitting element and the first microlens,
The second microlens is formed on an upper surface of the cap layer;
The light source device according to claim 10 or 11, wherein the cap layer has a function of ensuring an optical condensing interval between the first microlens and the second microlens.   The light source device according to any one of claims 10 to 12, wherein the functions of the first microlens and the second microlens include a condensing optical system or a telecentric optical system.   The light source device according to claim 10, wherein the light source element includes a crosstalk prevention layer having a side wall around the second microlens.   The light source device according to claim 1, wherein the surface-emitting light source element is an organic EL element, a VCSEL, or an LEDA.   The light source device according to claim 1, wherein the light source element includes an antireflection film between the surface-emitting light emitting element and the optical waveguide.   The light source device according to claim 1, wherein the substrate includes a plurality of the light source elements, and the microlenses of the light source elements are arranged in a straight line or in a staggered pattern. A light source device according to claim 17;
An image forming apparatus comprising: a photosensitive drum exposed by the light source device.

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