JP2009158672A - Light-emitting device, manufacturing method of the light-emitting device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of irradiating an irradiation position away from a light-emitting element with a relatively large quantity of light, to provide an image forming apparatus, and to provide a manufacturing method of the light-emitting device by which its manufacturing cost is relatively low. <P>SOLUTION: The optical device has the light-emitting element and an optical guide provided on a light-emitting surface of the light-emitting element. The optical device is characterized in that the optical guide is provided with a light transparent member having a refractive index higher than that of a region coming into contact with a side face of the optical guide and is disposed, having its main surface abut against an upper end surface of the optical guide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device, a method for manufacturing a light emitting device, and an image forming apparatus including the light emitting device.

  Conventionally, for example, as shown in Patent Document 1 below, in an optical printer head or the like for forming a latent image on the surface of a so-called charging drum, a light-emitting element array in which a plurality of light-emitting elements are arranged in a line has been used. ing. The light emitting element array is provided with a bonding wire for applying a control current for controlling light emission of each light emitting element, and a rotating charging drum and an optical printer head (for example, a light emitting element array or a bonding wire). In order to avoid contact with the photosensitive drum, it is necessary to secure a certain distance between the charging drum and the light emitting element array. In order to image light emitted from the light emitting element array on a chargeable surface separated from the light emitting element array by a certain distance, in a conventional optical printer head, for example, a SELFOC lens in which a plurality of gradient index rod lenses are arranged An array is used.

In recent years, there has been proposed an image forming medium that requires a larger amount of light than a charging drum for image formation, such as electronic paper described in Non-Patent Document 1 below.
JP 2007-7934 A “Challenging Frontiers of Electronic Paper”, EETIMS Japan 2006. 6.1 p. p. 40-50, published by E2 Publishing Co., Ltd., January 13, 2006

  When an optical printer head using the Selfoc lens array as described in Non-Patent Document 1 is used, a sufficient amount of light is imaged on an image forming medium that requires a relatively large amount of light. There was a problem that the forming medium could not be irradiated.

  The numerical aperture of the SELFOC lens array is relatively small (for example, about 0.4 at the maximum). Only light can propagate effectively. For this reason, in the light irradiation head using the SELFOC lens array, only a relatively small amount of light (for example, about 10% of the total amount of emitted light) is imaged on the image forming medium with respect to the light emitted from the light emitting element. I couldn't make it. In the case of a light irradiation head using a Selfoc lens array, the position and inclination of the Selfoc lens with respect to the light emitting element have a relatively large influence on the amount of light that can be irradiated. For this reason, since the position and inclination of the SELFOC lens array with respect to the light emitting element are set with relatively high accuracy, there has been a problem that assembly of the optical printer head requires relatively large effort and cost. The present invention has been made in view of the above problems, and a light emitting device, an image forming apparatus, and such a light emitting device capable of irradiating a relatively high amount of light with respect to an irradiation position separated from the light emitting element. It is an object of the present invention to provide a method of manufacturing a light emitting device head capable of manufacturing a device relatively easily.

  To achieve the above object, the present invention comprises a light emitting element and a light guide provided on a light emitting surface of the light emitting element, and the light guide has a refractive index in a peripheral region in contact with a side surface of the light guide. There is provided a light emitting device characterized in that a light transmissive member having a higher refractive index and having a first main surface in contact with an upper end surface of the light guide is further provided.

  A plurality of the light emitting elements are arranged, and the light guide is provided on each light emitting surface of the light emitting element, and the first main surface of the translucent member is the upper end surface of each of the plurality of light guides. It is preferable that any one of these is disposed in contact with each other.

  Further, a reference surface disposed at a position higher than the surface of the light emitting element is provided in a region other than the region where the light emitting element is disposed, and the translucent member is in contact with one main surface and the reference surface. Are preferably arranged.

  The light guide is preferably made of a cured photosensitive resin.

  Moreover, it is preferable that the said light guide is a column shape enclosed by the side surface substantially perpendicular | vertical to the surface of the said light emitting element.

  A conductive wire formed by wire bonding; and a driving IC that is electrically connected to the light emitting element through the conductive wire and sends a control current to each light emitting element. Is preferably at a position lower than the upper end surface of the light guide layer.

  The present invention also provides a recording medium on which an image is recorded on the surface by irradiating light emitted from the light emitting device and the light emitting element, the surface of the recording medium, and the other of the translucent substrate. An image forming apparatus including a transport mechanism that transports the main surface of the light-emitting element and a control mechanism that controls light emission of the plurality of light-emitting elements is also provided.

  The present invention also provides a step of forming a photosensitive resin layer on a surface of a substrate on which a plurality of light emitting elements are arranged, a portion of the photosensitive resin layer corresponding to the light emitting element, or the light emitting element. A step of selectively exposing a portion other than the portion to be developed, and a step of developing the exposed photosensitive resin layer to form a light guide layer having a higher refractive index than the surroundings on each surface of the light emitting element And after the step of forming the light guide layer, one main surface of the translucent substrate is provided on a reference surface provided at a position lower than the surface of the light emitting element in a region other than the region where the light emitting element is disposed A method of manufacturing a light-emitting device, comprising: a step of arranging the light-emitting device in contact with each other.

  According to the light emitting device of the present invention, it is possible to irradiate a relatively high amount of light with respect to an irradiation position separated from the light emitting element. According to the image forming apparatus of the present invention, it is possible to form a relatively good quality image even on an image forming medium that requires a relatively large amount of light. In addition, according to the method for manufacturing a light emitting device of the present invention, such a light emitting device can be relatively easily manufactured.

  Hereinafter, a light emitting device and a method for manufacturing the light emitting device according to the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention, which includes a light irradiation head 1 that is a first embodiment of a light emitting device according to the present invention. 2 is an enlarged partial side view showing the vicinity of the light emitting element 18 of the light irradiation head 1 in the image forming apparatus shown in FIG.

  An image forming apparatus 100 illustrated in FIG. 1 includes a light irradiation head 1, a transport mechanism 102 that transports a flat recording medium P in the sub-scanning direction (indicated by an arrow in FIG. 1), and a drive IC 15 for the light irradiation head 1. A control device 104 that supplies an image signal and controls the operation of the transport mechanism 102 is provided. The recording medium P of the present embodiment uses, for example, a photochromic compound that has a property of developing color when irradiated with light of the first wavelength and decoloring when irradiated with light of the second wavelength. It is made of known electronic paper. In general, color development in a known electronic paper using a photochromic compound requires a larger amount of light than the amount of light required for forming a latent image on the surface of a photosensitive drum in a known printer. The image forming apparatus 100 according to this embodiment is an apparatus for irradiating a flat recording medium P with a relatively large amount of light. The image recording medium is not limited to a known electronic paper using a photochromic compound, and other types of electronic paper may use various photoreceptors. In the present invention, an image recording medium that is an object on which an image is formed is not particularly limited.

  The light irradiation head 1 includes a light emitting element array body 10 in which a plurality of light emitting elements 18 having a light guide layer 16 provided on an upper surface thereof are arranged on a substrate 11 in a main scanning direction (a direction perpendicular to the sub scanning direction); A circuit board 14 on which a driving IC 15 that emits a control signal for controlling the light emission operation of each light emitting element 18 is disposed, a metal housing 20 on which the light emitting element array body 10 is installed, and an upper end surface of the light guide layer 16 16A and a translucent substrate 12 disposed in contact with a later-described reference surface 20A of the metal housing 20.

  The substrate 11 of the light emitting element array 10 is a gallium arsenide (GaAs) substrate, for example, and a plurality of light emitting elements 18 are formed on the substrate 11 by a known semiconductor manufacturing technique. In the light-emitting element 18 of the present embodiment, a boundary portion (so-called pn junction portion) between two types of semiconductor layers emits light, and light is emitted from the upper surface of the light-emitting element 18 (the upper surface in FIGS. 1 and 2). It is a well-known LED element. The light-emitting element 18 is formed by forming a plurality of semiconductor films having different polarities on the substrate 11 and patterning the formed semiconductor layers into a predetermined shape using a technique such as dry etching or wet etching. is doing. The film formation layer on the substrate 11 is made of aluminum gallium arsenide (AlGaAs), aluminum indium gallium phosphide (AlInGaP), aluminum indium gallium arsenide (AlInGaAs), gallium phosphorus (GaP), aluminum indium phosphide (AlInP), indium, or the like. The composition thereof, such as gallium phosphide (InGaP), is not particularly limited, and may be appropriately selected depending on the desired emission wavelength. Also, the composition of the semiconductor substrate is not particularly limited, and for example, gallium phosphide (GaP), silicon (Si), or the like can be used. Further, the composition and configuration of the light-emitting element in the present invention are not particularly limited.

  An electrode 19 is formed on the surface of the substrate 11. When a current is supplied to the light emitting element 18 through the electrode 19, the light emitting element 18 emits light. Similarly to the light emitting element 18, the electrode 19 is also formed on the substrate 11 using a known semiconductor manufacturing technique. The electrode 19 is heat-treated, and the contact state with each light emitting element 18 is relatively good. The electrode 19 is electrically connected to a conductor pattern (not shown) formed on the circuit board 14 via a metal wire 17 formed using a known wire bonding technique. This conductor pattern (not shown) The drive IC 15 arranged on the substrate 14 is connected.

  A light guide layer 16 is formed on each of the upper surfaces 18 </ b> A of the plurality of light emitting elements 18 formed on the substrate 11. The light guide layer 16 has a cross-sectional shape corresponding to the light irradiation region of the light emitting element 18, that is, the shape of the upper surface, and in this embodiment, the cross section has a substantially rectangular shape. The light guide layer 16 propagates light emitted from the upper surface 18A of the light emitting element 18 in a direction substantially perpendicular to the upper surface 18A of the light emitting element 18 (upward direction in FIG. 1). The light guide layer 16 of the present embodiment does not need to have a function of condensing the light emitted from the light emitting element 18 or converting the phase of the light emission, and is generated from the upper surface 18A of the light emitting element 18. Light energy propagates in a direction substantially perpendicular to the upper surface 18A of the light emitting element 18 (upward direction in FIG. 1) with relatively little energy loss. In the present embodiment, the cross-sectional shape of the light guide layer is a shape corresponding to the shape of the light irradiation region (that is, the upper surface) of the light emitting element. In the present invention, the cross-sectional shape of the light guide does not need to be a shape corresponding to the light irradiation region of the light emitting element, and the shape of the light guide is not particularly limited. For example, the cross-sectional shape of the light guide may be a substantially circular shape with respect to the substantially rectangular light irradiation region, or may be a triangular shape or a polygonal shape equal to or more than a quadrangular shape.

  The light guide layer 16 is made of a material having a higher refractive index than the surroundings for light in a desired wavelength range. In the present embodiment, the light guide layer 16 is formed of a material having a refractive index higher than that of air for light having a wavelength of 600 nm, that is, a material having a refractive index larger than 1. In the present embodiment, the light guide layer 16 has a refractive index of, for example, 1.49 for light having a wavelength of at least 600 nm. The light guide layer 16 of the present embodiment is formed of a photosensitive resin, specifically, a so-called negative resist. A method for forming the light guide layer 16 and a method for manufacturing the light irradiation head 1 will be described in detail later.

In general, when light is incident from a medium having a certain refractive index n ₁ to a medium having a smaller refractive index n ₀ , if the incident angle of light at the interface between the two is equal to or greater than the total reflection angle θ, reflect. For the total reflection angle θ, sin θ = n ₀ / n ₁ holds. In this embodiment, for light having a wavelength of 600 nm, n ₁ = 1.49 and n ₀ = 1.0, so the total reflection angle θ is 42.1 degrees. That is, of the light emitted from the upper surface of the light emitting element 18, the radiation angle θ ′ (see FIG. 2) = (90−θ) with respect to the main line L (see FIG. 2) of light substantially perpendicular to the upper surface of the light emitting element 18. ) = Light within 47.9 degrees is guided in the upper direction of FIGS. 1 and 2 through the light guide layer 16 with relatively little light loss. In general, the emitted light intensity I (φ) from an LED element such as the light emitting element 18 has a so-called Lambert distribution represented by I (φ) = I ₀ · cos (φ). Here, I ₀ is the light intensity in the main line L direction, and φ is an angle formed with respect to the main line L direction. The light emission from the light emitting element 18 according to the Lambert distribution includes a light amount of about 55.0% of the total light emission amount within a range of φ = θ ′ = 47.9 degrees. In the present embodiment, about 55.0% of the light emitted from the light emitting element 18 propagates (guides light) while totally reflecting the light guide layer 16.

  The translucent substrate 12 is made of, for example, a glass substrate, and one main surface 12B is in contact with the upper end surface 16A of the light guide layer 16. As the translucent substrate 12, for example, a thin glass having a film thickness of 50 μm may be used. The material of the present glass may be an optical transparent material such as BK7, flint glass, F2, BaK1, phased silica, crown glass, sapphire, selenium zinc, calcium fluoride. The translucent substrate 12 is in contact with the reference surface 20A of the metal housing 20 and is relatively firmly coupled to the reference surface 20A of the metal housing 20 by, for example, an adhesive. Accordingly, in the image forming apparatus 100, when the light transmitting substrate 12 and the recording medium P are in contact with each other, the positional deviation between the light emitting element array body 10 disposed in the metal housing 20 and the light transmitting substrate 12 occurs. Is suppressed. Thereby, the light guide layer 16 is also prevented from falling off the light emitting element 18.

  The translucent substrate 12 preferably has a refractive index substantially equal to that of the light guide layer 16 for light in a desired wavelength range among the light emitted from the light emitting element 18. In the present embodiment, for example, the refractive index is about 1.49 for light with a wavelength of 600 nm. Since the refractive indexes of the light guide layer 16 and the translucent substrate 12 are substantially equal, the light guide layer 16 and the translucent substrate 12 of the light incident on the translucent substrate 12 from the light guide layer 16 The reflection at the interface can be set to be relatively small. Note that “substantially equivalent” means that the refractive index of the light guide layer 16 is within a range of ± 30%. In addition, it is preferable that the refractive index of the translucent board | substrate in this invention exists in the range within +/- 10% with respect to the refractive index of the light guide layer 16. FIG. The light emitted from the upper surface 18A of the light emitting element 18 propagates through the light guide layer 16, enters the light transmitting substrate 12 from one main surface 12B, and exits from the other main surface 12B of the light transmitting substrate 12. To do. In the present embodiment, in the image forming apparatus 100, a relatively large amount of light of about 55% of the light emitted from the upper surface 18 </ b> A of the light emitting element 18 propagates through the light guide layer 16 and the translucent substrate 12. The recording medium P is irradiated.

  As described above, in order to form an image on the recording medium P made of electronic paper using a photochromic compound, for example, it is necessary to irradiate the electronic paper with a relatively large amount of light. The light emitted from the upper surface 18A of the light emitting element 18 becomes stronger (the amount of light) becomes closer to the upper surface 18A. For example, when it is desired to irradiate the recording medium P with as much light as possible, it is desirable that the electronic paper and the upper surface 18A of the light emitting element 18 be as close as possible. However, in order to prevent contact between the light emitting element 18 and the recording medium P, the upper surface 18A of the light emitting element 18 and the recording medium P need to be separated by a certain distance. In addition, a metal wire 17 for transmitting an image signal is provided on the electrode 19 of each light emitting element 18. In order to prevent the metal wire 17 from contacting the recording medium P, a relatively large separation distance is provided. Need to keep. If the light guide layer 16 and the translucent substrate 12 are not disposed, the recording medium is sufficiently separated from the light emitting element 18 and the recording medium P so that the metal wire 17 and the recording medium P do not come into contact with each other. The light applied to P is relatively weak. In addition, the spatial distribution of light intensity is a distribution in which the central peak of the light intensity is low and spreads gently. For this reason, if the light guide layer 16 and the translucent substrate 12 are not arranged, the image formed on the recording medium P is weakly colored and a blurred image.

  In the image forming apparatus 1 of the present embodiment, the light guide layer 16 and the translucent substrate 12 are provided, and the light emitting element 18 and the recording medium P are sufficiently large so that the metal wire 17 and the recording medium P do not contact each other. The metal wire 17 and the recording medium P are prevented from contacting each other. Further, as described above, the light guide layer 16 is prevented from falling off the light emitting element 18 by the translucent substrate 12. In addition, in the image forming apparatus 1 of the present embodiment, the light guide layer 16 and the translucent substrate 12 have a relatively large amount of light of about 55% of the light emitted from the upper surface 18A of the light emitting element 18. Is irradiated onto the recording medium P. The light propagating through the light guide layer 16 is emitted from the upper end surface of the light guide layer 16 while maintaining the radiation angle θ ′ from the upper surface 18A of the light emitting element 18. In the image forming apparatus 1, while suppressing the metal wire 17 and the like from contacting the recording medium P, the amount of light applied to the recording medium P is relatively increased, and the light applied to the recording medium P is reduced. The spatial distribution can have a relatively steep central peak. By using the image forming apparatus 1 of the present invention, an image with relatively good color reproducibility and relatively high resolution can be formed on the recording medium P.

  In the present embodiment, the light emitting element array body 10 is installed on the surface of a metal housing 20 made of, for example, aluminum. Specifically, the lower surface of the substrate 11 of the light emitting element array body 10 is placed on the metal housing 20, and the substrate 11 and the metal housing 20 are bonded together by, for example, an adhesive. Metal housings are aluminum (Al), copper (Cu), iron (Fe), carbon (C), nickel copper (Ni, Cu), nickel manganese steel (including Ni, Mn), chromium vanadium steel (including Cr, V), stainless steel (including C, Ni, Cr, Mo), aluminum alloys (including Mn, Mg, Cr, Si, Zn, Cu), copper alloys (including Mn, Ni, P), etc. can be used. The material is not particularly limited, but aluminum or copper excellent in heat conduction is preferable. The housing is not limited to being made of metal.

  In the present embodiment, for example, a silicone adhesive having excellent thermal conductivity is used for joining the substrate 11 and the metal housing 20. As described above, in order to form an image on the recording medium P made of electronic paper using a photochromic compound, for example, it is necessary to irradiate the electronic paper with a relatively large amount of light. In order to irradiate a relatively large amount of light, the current energy supplied to the light emitting element 18 that is an LED also needs to be relatively large. In the present embodiment, relatively large current energy is input to a relatively small region of the light emitting element array 10 to obtain a relatively large amount of light emission. That is, in the light emitting element array 10 of the present embodiment, the energy density is relatively high, and the heat generation amount of the light emitting element 18 is also relatively high. In the present embodiment, the light emitting element array 10 is mounted on the surface of the metal casing 20, and heat generated in the light emitting elements 18 is transferred relatively well to the metal casing 20, and relatively relatively from the surface of the metal casing 20. Heat is dissipated with high efficiency. The adhesive used for joining the substrate 11 and the metal housing 20 is not particularly limited, such as an epoxy adhesive or an acrylic adhesive, but the heat energy generated in the light emitting element 18 is relatively good for the metal housing 20. In order to transfer heat to the heat and dissipate heat, it is preferable to use a silicone adhesive having excellent thermal conductivity.

  In the above embodiment, the light emitting element array body 10 in which a plurality of light emitting elements 18 are arranged on the substrate 11 is installed in the metal casing 20 having the reference surface 20A, and the metal casing 20 is fixed to the circuit board 14. ing. A through hole corresponding to the outer shape of the metal housing 20 is formed in the circuit board 14, the metal housing 20 is disposed in the through hole, and the inner wall surface of the metal housing 20 and the through hole is For example, it is fixed by an adhesive or the like. The configuration of the light emitting device of the present invention is not limited to such an embodiment. FIG. 3 is a schematic perspective view for explaining the light irradiation head 2 which is the second embodiment of the light emitting device of the present invention. Hereinafter, although the light irradiation head 2 is demonstrated, the site | part similar to 1st Embodiment is demonstrated using the code | symbol similar to 1st Embodiment.

  In the light irradiation head 2, a driving IC 15 (not shown in FIG. 3) and a wiring pattern are directly formed on the substrate 11 on which the light emitting elements 18 are arranged, and the substrate 11 is directly disposed on the surface of the metal plate 40. . On the surface of the substrate 11, for example, a metal frame 42 is provided so as to surround the plurality of light emitting elements 18, and the transmitted light substrate 12 contacts the reference surface 20 </ b> A that is the upper surface of the frame 42. Connected and joined. Similar to the first embodiment, the translucent substrate 12 has one main surface 12B in contact with the upper end surface 16A of the light guide layer 16. In the second embodiment, the ratio of metal members is larger than in the first embodiment, and the heat dissipation effect of the thermal energy generated in the light emitting element 18 is relatively large. The structure of the light emitting device of the present invention is not particularly limited.

  The driving IC 15 of the light irradiation head 1 is connected to the control device 104 and receives an image signal sent from the control device 104. The control device 104 is composed of, for example, a known computer having a data input / output port, and transmits an image signal corresponding to image data input from the outside to the drive IC 15. The drive IC 15 supplies current to each light emitting element 18 according to the image signal received from the control device 104, and causes each light emitting element 18 to emit light according to the image to be formed. The control device 104 is also connected to the transport mechanism 102 and transports the recording medium P in the sub-scanning direction at a speed corresponding to the image signal. The transport mechanism 102 may be any known paper surface transport mechanism configured with, for example, a plurality of rollers and roller pairs, and the configuration is not particularly limited. In the image forming apparatus of the present invention, even if the recording medium requires a relatively large amount of light for image formation, such as electronic paper using a photochromic compound, the color reproducibility is relatively low on the surface of the recording medium. A high and relatively high-definition two-dimensional image can be formed.

  Next, an example of a method for manufacturing a light emitting device of the present invention will be described. FIG. 4 is a schematic cross-sectional view illustrating a method for manufacturing the light irradiation head 1. FIG. 5 is a flowchart of the method for manufacturing the light irradiation head 1. First, the substrate 11 having a plurality of light emitting elements 18 formed on the surface is prepared (step S102). The light emitting element 18 may be manufactured on the substrate 11 using, for example, a known semiconductor manufacturing method. At this stage, the substrate 11 is handled in a wafer size, not a chip size as arranged in one of the light irradiation heads 1.

  Next, a negative resist is applied to the surface of the substrate 11 on which the light emitting element 18 is arranged, and a resist film 52 is formed (step S104). In this embodiment, for example, TMMR S2000 thick film resist manufactured by Tokyo Ohka Co., Ltd. is applied to the surface of the substrate 11 by spin coating. The film thickness of the resist film 52 is, for example, 100 μm. This film thickness is such that when the substrate 11 is placed on the metal housing 20 in step S108 described later, the surface of the light guide layer 16 is on the upper side of the reference surface 20A of the metal housing 20 (upper side in FIG. 4). The film thickness is set to be The type of the resist is not particularly limited, and may be appropriately selected according to the emission wavelength from the light emitting element 18 or the wavelength range desired to be irradiated on the surface of the recording medium P. The resist may be negative or positive.

  Next, a well-known photolithography process is performed on the range film 52 formed on the substrate 11 in the wafer state to form the light guide layer 16 made of a resist (step S106). In the present embodiment, the resist film 52 is a negative resist, and a region corresponding to the light emitting element 18 of the resist film 52 is irradiated with light, followed by development and post baking, and a columnar light guide layer on the surface of the light emitting element 18. 16 is formed.

In post-baking, the entire substrate 11 in the wafer state was cured and stabilized by heat treatment in the range of 200 to 300 degrees Celsius.

  Next, the wafer-like substrate 11 on which the light guide layer 16 is formed is cut into chip sizes by, for example, a known dicing process, and the substrate 11 of each chip size is placed on the metal housing 20 (step S108). As described above, the substrate 11 and the metal casing 20 are bonded using a silicone-based adhesive. In this state, the upper end surface 16A of the light guide layer 16 is on the upper side (the upper side in FIG. 4) with respect to the reference surface 20A of the metal housing 20.

  Next, the metal housing 20 on which the substrate 11 is installed is fixed to the circuit board 14, and the metal wire 17 formed by using a known wire bonding technique and the electrode 19 provided for each light-emitting element 18 and not shown. The conductor pattern is connected (step S110). At this time, the topmost portion 17A of the metal wire 17 is set to be positioned below the reference plane 20A.

  Next, the translucent substrate 12 abuts on the reference surface 20A of the metal housing 20, and is joined to the reference surface 20A of the metal housing 20 by, for example, an adhesive (step S112). In addition, you may join the translucent board | substrate 12 and the reference surface 20A, for example with photocurable resin. As described above, the surface of the light guide layer 16 is on the upper side (upper side in FIG. 4) with respect to the reference surface 20A of the metal housing 20, and the translucent substrate 12 is the upper end surface 16A of the light guide layer 16. The transparent substrate 12 and the upper end surface 16A of the light guide layer 16 are in close contact with each other without a gap. The light emitting device of the present invention can be manufactured through the above-described steps, for example.

6 (a) and 6 (b) are diagrams for explaining the effect of the light emitting device of the present invention. FIG. 6A is a graph obtained by measuring the light emission intensity distribution of an embodiment of the light emitting device of the present invention, and FIG. 6B is a graph obtained by measuring the light emission intensity distribution of an embodiment of a conventional light irradiation head. It is. Specifically, FIG. 6A shows light intensity distribution data measured by bringing the light receiving surface of the light intensity sensor into contact with the surface of the light transmitting substrate 12 of the light irradiation head 1 shown in FIG. is there. The light irradiation head 1 used for acquiring the data shown in FIG. 6 (a) was a light guide layer 16 having a thickness of 140 μm and a light-transmitting substrate 12 having a thickness of 50 μm. That is, the data shown in FIG. 6A is light intensity distribution data at a position spaced 210 μm away from the upper surface 18A of the light emitting element 18 in a substantially vertical direction. The vertical axis in FIG. 6A indicates the light intensity (unit: W / m ² ), and the horizontal axis in FIG. 6A indicates the position in space. In the data of FIG. 6A, a plurality of light emitting elements 18 are caused to emit every other light. Specifically, among the light emitting elements 18 arranged at the positions indicated by arrows P1 to P7 in FIG. 6A, only the light emitting elements 18 indicated by arrows P2, P4, and P6 are selectively caused to emit light. .

  In FIG. 6A, the light emission intensity distribution from the light irradiation head having the configuration in which the light guide layer 16 and the translucent substrate 12 are removed from the light irradiation head 1 that acquired the data shown in FIG. 6A was measured. It is a graph. The data shown in FIG. 6B is light intensity distribution data measured by arranging the light receiving surface of the intensity sensor at a position 100 μm away from the upper surface 18A of the light emitting element 18 in a substantially vertical direction. That is, the data shown in FIG. 6B is light intensity distribution data at a position 100 μm away from the upper surface 18A of the light emitting element 18 in a substantially vertical direction. Note that the data in FIG. 6B is also data obtained by causing every other light emitting element 18 to emit light. Specifically, among the light emitting elements 18 arranged at the positions indicated by arrows P′1 to P′7 in FIG. 6B, the light emitting elements indicated by arrows P′2, P′4, and P′6. Only 18 is made to emit light selectively. Note that, in the graph shown in FIG. 6A and the graph shown in FIG. 6B, one auxiliary scale interval on the vertical axis is the same amount of light amount difference.

  As can be seen by comparing FIG. 6A and FIG. 6B, in the case of the conventional light irradiation head shown in FIG. 6B, the area is relatively close to 100 μm from the surface of the light emitting element 18. However, the absolute value of the amount of light applied is relatively small, and the light intensity distribution is not steep. For example, in the data shown in FIG. 6B, not only the portions corresponding to the arrows P2, P3, and P4 corresponding to the light emitting elements 18 that selectively emit light, but also the portions that did not emit light (arrows P1, P3,. A certain amount of light is irradiated to the portions P5 and P7). On the other hand, in the light irradiation head 1 provided with the light guide layer 16 and the translucent substrate 12 shown in FIG. 6A, light with sufficient intensity is irradiated even at a location sufficiently separated from the light emitting element 18 by 250 μm. And has a steep light distribution centering on the arrangement positions P2, P4, and P6 of the light emitting element 18. If the light emitting device of the present invention is used, for example, a recording medium that requires a relatively large amount of light for image formation, such as electronic paper using a photochromic compound, the color reproducibility is compared with the surface of the recording medium. And a relatively high-definition two-dimensional image can be formed.

  The light emitting device, the light emitting device manufacturing method, and the image forming apparatus of the present invention have been described above. However, the light emitting device, the light emitting device manufacturing method, and the image forming apparatus of the present invention are not limited to the above embodiments. Of course, various improvements and modifications may be made without departing from the scope of the present invention.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention configured to include a light emitting head that is one embodiment of a light emitting device according to the present invention. FIG. 2 is a partial side view showing an enlarged view of the vicinity of a light emitting element of a light irradiation head in the image forming apparatus shown in FIG. 1. It is a schematic perspective view explaining other embodiment of the light-emitting device of this invention. It is a schematic sectional drawing explaining one Embodiment of the manufacturing method of the light emitting device of this invention. It is a flowchart figure of one Embodiment of the manufacturing method of the light-emitting device of this invention. (A) And (b) is a figure for demonstrating the effect of the light-emitting device of this invention, and is the graph which measured the light emission intensity distribution of the light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light irradiation head 10 Light emitting element array body 11 Board | substrate 12 Translucent board | substrate 14 Circuit board 15 Drive IC
16 Light guide layer 16A Upper end surface 17 Metal wire 17A Topmost portion 18 Light emitting element 18A Upper surface 19 Electrode 20 Metal housing 20A Reference surface 25 Resist film 100 Image forming apparatus 102 Conveying mechanism 104 Control apparatus

Claims (8)

A light emitting element;
A light guide provided on the light emitting surface of the light emitting element,
The light guide has a higher refractive index than the refractive index of the peripheral region in contact with the side surface of the light guide,
A light-emitting device, further comprising a translucent member disposed such that the first main surface is in contact with the upper end surface of the light guide. A plurality of the light emitting elements are arranged, and the light guide is provided on each light emitting surface of the light emitting element,
The light emitting device according to claim 1, wherein the first main surface of the translucent member is disposed in contact with any one of the upper end surfaces of each of the plurality of light guides. In a region other than the region where the light emitting element is disposed, a reference surface disposed at a position higher than the surface of the light emitting element,
The light-emitting device according to claim 1, wherein the translucent member is disposed such that one main surface and the reference surface are in contact with each other.   The light-emitting device according to claim 1, wherein the light guide is made of a cured photosensitive resin.   The light-emitting device according to claim 1, wherein the light guide has a column shape surrounded by a side surface substantially perpendicular to a surface of the light-emitting element. A conductive wire formed by wire bonding;
A drive IC electrically connected to the light emitting element via the conductive wire, and for sending a control current to each light emitting element;
The light emitting device according to claim 1, wherein a top portion of the conductive wire is located at a position lower than an upper end surface of the light guide layer. The light emitting device according to any one of claims 1 to 6,
A recording medium on which an image is recorded on the surface by being irradiated with light emitted from the light emitting element is conveyed in a state where the surface of the recording medium and the other main surface of the translucent substrate face each other. A transport mechanism;
A control mechanism for controlling light emission of the plurality of light emitting elements;
An image forming apparatus comprising: Forming a photosensitive resin layer on a surface of a substrate on which a plurality of light emitting elements are disposed;
Selectively exposing a portion of the photosensitive resin layer corresponding to the light emitting element or a portion other than the portion corresponding to the light emitting element;
Developing the exposed photosensitive resin layer to form a light guide layer having a higher refractive index than the surroundings on each surface of the light emitting element;
After the step of forming the light guide layer,
A step of placing one main surface of the translucent substrate in contact with a reference surface provided at a position lower than the surface of the light emitting element in a region other than the region where the light emitting element is disposed;
A method for manufacturing a light-emitting device, comprising:

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