JP2011131457A - Light source device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device allowing light emitting elements to be arranged in high density even in the case of adopting a system for emitting light emitted from the light emitting elements, from the end face of an element substrate, and an image forming apparatus including the light source device as an exposure head. <P>SOLUTION: The exposure head 10 (the light source device) includes the element substrate (a first element substrate 71 and a second element substrate 72) formed with a plurality of organic EL elements 5 (the light emitting elements) in an X-direction as a light source. Each organic EL element 5 includes a first electrode, a light emitting function layer and a second electrode laminated in the thickness direction of the element substrate. The element substrate is formed with light guides 4 for the organic EL elements 5 to emit the light emitted from the organic EL elements 5, from the end faces 711, 721 located on one side in the Y-direction of the element substrate. Further, the first element substrate 71 and the second element substrate 72 are superimposed in the thickness direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source device using a light emitting element formed on an element substrate as a light source, and an image forming apparatus including the light source device.

  In image forming apparatuses such as printers, copiers, and facsimiles, it has been proposed to use a light source device that uses an organic electroluminescence element formed on an element substrate as a light source as an exposure head. In addition, for use as an exposure light source, an organic electroluminescence element with high power and high directivity is required. However, when the power is increased with an organic electroluminescence element having a conventional general configuration, the burden is large and the lifetime is greatly increased. To drop. Therefore, an element structure in which the area of the light extraction part is made smaller than the actual light emitting part area, and a structure combining a scattering layer, a light guide structure, a diffraction grating, etc. are proposed so as to increase the external extraction efficiency and directivity. Has been. Among these configurations, the structure that emits light from the end face of the element substrate has an advantage that the area of the light extraction portion can be considerably smaller than the actual light emission portion area (see, for example, Patent Documents 1 to 3). .

Japanese Patent No. 3730573 JP-A-9-226171 JP 2009-51152 A

  However, in the case of a structure in which light is emitted from the end face of the element substrate, the organic electroluminescent elements can be arranged only in the longitudinal direction along the end face, so that the organic electroluminescent elements cannot be arranged at a high density. There is. For this reason, there is a problem in that an image forming apparatus using a light source device that employs a method of emitting light from an end face of an element substrate as an exposure head cannot obtain high resolution.

  In view of the above problems, an object of the present invention is to provide a light source device capable of arranging light emitting elements at high density even when a method of emitting light emitted from the light emitting elements from the end face of the element substrate is adopted. Another object of the present invention is to provide an image forming apparatus provided with the light source device as an exposure head.

  In order to solve the above-described problems, the present invention provides a light source device that uses a light-emitting element in which a first electrode, a light-emitting functional layer, and a second electrode are stacked in the thickness direction of an element substrate as a light source. A first element substrate in which a plurality of first light emitting elements are arranged in the X direction, and light emitted from the first light emitting elements when the directions intersecting each other in the inward direction are the X direction and the Y direction, and the first element substrate A plurality of first light guides that are emitted from an end face located on one side in the Y direction and a plurality of second light emitting elements are arranged in the X direction, and are arranged so as to overlap the first element substrate in the thickness direction. An element substrate, and a second light guide path that emits light emitted from the second light emitting element from an end surface located on the one side in the Y direction of the second element substrate.

  In the present invention, a plurality of light emitting elements are formed in the X direction as light sources on the element substrate, and the light emitting element includes a first electrode, a light emitting functional layer, and a second electrode stacked in the thickness direction of the element substrate. I have. For this reason, the light emitting element emits light toward the normal direction of the substrate surface of the element substrate. In addition, for the light emitting element, a light guide path that emits light emitted from the light emitting element from an end face located on one side in the Y direction of the element substrate is formed, so that the light emitted from the light emitting element is The light is emitted from the end face of the element substrate. For this reason, since the area of the light extraction part is smaller than the actual light emitting part area of the light emitting element, light with high power density and high directivity can be emitted without imposing a large burden on the light emitting element. Therefore, the reliability of the light source device can be improved. Furthermore, in the present invention, a structure in which a first element substrate in which a plurality of first light emitting elements are arranged in the X direction and a second element substrate in which a plurality of second light emitting elements are arranged in the X direction are stacked in the thickness direction. Therefore, even when a method of emitting light emitted from the light emitting element from the end face of the element substrate is employed, the light emitting elements can be arranged with high density.

  In the present invention, it is preferable that the first light emitting element and the second light emitting element are provided at positions shifted in the X direction. With this configuration, the light emitting elements can be arranged with high density in the X direction.

  In the present invention, the first light emitting elements are provided at equal intervals in the X direction, and the second light emitting elements are provided at equal intervals in the X direction with the same interval as the first light emitting elements. The first light emitting element is preferably provided at a central position between two second light emitting elements adjacent in the X direction. If comprised in this way, the effect similar to having arrange | positioned the light emitting element by the double density in the X direction can be acquired.

  In the present invention, it is preferable that the first light emitting element and the second light emitting element have a length in the Y direction larger than a width in the X direction. If comprised in this way, the light radiate | emitted from the light emitting element can be radiate | emitted from the end surface of an element substrate with high power density.

  In the present invention, the first light guide path and the second light guide path preferably have a cross-sectional area that increases from the other side opposite to the one side in the Y direction toward the one side. If comprised in this way, the light radiate | emitted from the light emitting element can be radiate | emitted efficiently from the end surface of an element substrate.

  In the present invention, it is preferable that the first light guide is formed integrally with the first element substrate, and the second light guide is formed integrally with the second element substrate. If comprised in this way, a light guide path and a light emitting element can be arrange | positioned with high positional accuracy.

  In the present invention, the first light emitting element and the second light emitting element are, for example, organic electroluminescent elements (hereinafter referred to as organic EL elements).

  The light source device to which the present invention is applied can be used for various optical devices. For example, a light source device to which the present invention is applied can be used as an exposure head of an image forming apparatus, and the image forming apparatus has an image carrier on which a latent image is formed by light emitted from the light source. Yes.

1 is a perspective view showing main parts of an exposure head and an image forming apparatus according to Embodiment 1 of the present invention. It is explanatory drawing which shows the structure of the exposure head etc. which concern on Embodiment 1 of this invention. It is explanatory drawing of the lens array used for the exposure head which concerns on Embodiment 1 of this invention. It is explanatory drawing of the organic electroluminescent apparatus used for the exposure head concerning Embodiment 1 of this invention. In the exposure head which concerns on Embodiment 1 of this invention, it is explanatory drawing which shows the cross-sectional structure of the light emitting element comprised in the element substrate which comprises an organic EL apparatus, and a light guide. It is explanatory drawing of the organic EL apparatus used for the exposure head which concerns on Embodiment 2 of this invention. In the exposure head which concerns on Embodiment 2 of this invention, it is explanatory drawing which shows the cross-sectional structure of the light emitting element and light guide path which were comprised on the element board | substrate which comprises an organic EL apparatus. In the exposure head which concerns on Embodiment 3 of this invention, it is explanatory drawing which shows the cross-sectional structure of the light emitting element comprised in the element substrate which comprises an organic EL apparatus, and a light guide. In the exposure head which concerns on Embodiment 4 of this invention, it is explanatory drawing which shows the cross-sectional structure of the light emitting element and light guide path which were comprised on the element board | substrate which comprises an organic EL apparatus. In the exposure head which concerns on Embodiment 4 of this invention, it is explanatory drawing which shows the cross-sectional structure of the light emitting element and light guide path which were comprised on the element board | substrate which comprises an organic EL apparatus. 1 is a longitudinal sectional view showing an overall configuration of an image forming apparatus to which the present invention is applied. It is a longitudinal cross-sectional view which shows the whole structure of another image forming apparatus to which this invention is applied.

  Embodiments of the present invention will be described with reference to the drawings. In the following description, an example in which an electro-optical device to which the present invention is applied is used as an exposure head of an image forming apparatus will be mainly described. In the drawings referred to below, the scale of each member is shown different from the actual structure so that the configuration of each member can be easily recognized. Further, in order to make it easy to understand the positional relationship between the members, in the following description, the directions intersecting each other in the in-plane direction of the element substrate are defined as the X direction and the Y direction, and the direction perpendicular to the substrate surface of the element substrate is defined. The description will be made with the Z direction. Further, elements and circuits for driving and controlling the electro-optical device are omitted.

[Embodiment 1]
(Configuration of image forming apparatus)
FIG. 1 is a perspective view showing the main parts of an exposure head and an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an explanatory view showing the configuration of the exposure head and the like according to Embodiment 1 of the present invention, and FIGS. 2A and 2B are explanatory views showing the cross-sectional configuration of the exposure head and the like, and the organic EL It is explanatory drawing which shows the light-projection part of an apparatus.

  An image forming apparatus 100 shown in FIG. 1 is an apparatus used as a printing portion of a printer, a copier, a facsimile, or the like, and a cylinder extending in a bus direction extending in the X direction (main scanning direction indicated by an arrow A). A photosensitive drum 110 (image carrier), and an exposure head 10 (light source device) disposed on the outer side in the radial direction of the photosensitive drum 110. The photosensitive drum 110 includes an image bearing surface 110s on a circumferential surface (outer circumferential surface), and upper ends of two columns 137 extending upward (Y direction) in the frame 130 of the image forming apparatus 100. Is supported so as to be rotatable around the axis R (direction indicated by arrow B / sub-scanning direction). In addition, the photosensitive drum 1100 rotates around the axis R by receiving rotational driving from a driving device (not shown) at the upper end of the support column 137.

  The exposure head 10 is disposed on the bottom plate portion 135 of the frame 130, and irradiates light toward the image bearing surface 110s located in the Y direction from the outer side in the radial direction of the photoconductor drum 110 to be placed on the image bearing surface 110s. A latent image is formed.

  As shown in FIGS. 1 and 2A, the exposure head 10 includes an organic EL device 70 having a light emitting element described later, and a lens array 20 disposed between the organic EL device 70 and the photosensitive drum 110. And a translucent spacer 30 that is interposed between the organic EL device 70 and the lens array 20 and defines the distance between the organic EL device 70 and the lens array 20.

  As shown in FIG. 2B, the organic EL device 70 includes two rows of a plurality of light emitting portions 40 arranged in the extending direction (X direction) of the axis R of the photosensitive drum 110. In the row, the position of the light emitting unit 40 is shifted in the direction of the generatrix of the photosensitive drum 110. Particularly in this embodiment, in each row, the light emitting portions 40 are arranged at equiangular intervals in the X direction, and the light emitting portions 40 in one row are adjacent to each other in the other row in the X direction. 40 in the center position. For this reason, the pitch of the light emitting portions 40 in each row is P, but when the entire two rows of the light emitting portions 40 are viewed, the light emitting portions 40 are arranged at a pitch of P / 2.

(Configuration of the lens array 20)
FIG. 3 is an explanatory diagram of the lens array 20 used in the exposure head 10 according to Embodiment 1 of the present invention. As shown in FIG. 3, in the lens array 20, a plurality of rod lenses 23 are arranged corresponding to the staggered layout of the light emitting portions 40 shown in FIG. The rod lens 23 is a gradient index lens, and the lens array 20 is configured as a converging lens array. The gradient index rod lens 23 is a graded index optical fiber formed such that the refractive index at the central axis, that is, the optical axis is low, and the refractive index increases as the distance from the central axis increases. An erect image can be formed on the photosensitive drum 110 by transmitting the emitted light. Specific examples of such a converging lens array include, for example, SLA (Selfoc Lens Array (“Selfoc” is a registered trademark of Nippon Sheet Glass Co., Ltd.)) available from Nippon Sheet Glass Co., Ltd.

  In the lens array 20, the rod lens 23 has a diameter of about 0.28 mm and is accommodated in the housing 26. In the housing 26, the gap between the rod lenses 23 is filled with black silicone resin 24, and the plurality of rod lenses 23 are integrated. In this configuration, an erect image rod lens array is used, but a configuration in which a microlens array of an inverted reduction optical system formed by UV curable resin molding may be used.

(Detailed configuration of exposure head 10)
FIG. 4 is an explanatory diagram of the organic EL device 70 used in the exposure head 10 according to Embodiment 1 of the present invention. FIGS. 4 (a), 4 (b), and 4 (c) show the organic EL device 70 as light. It is explanatory drawing seen from the radiation | emission part side, explanatory drawing which shows a mode that the organic EL apparatus was decomposed | disassembled into the 1st element substrate and the 2nd element substrate, and explanatory drawing which shows the planar structure of an element substrate. FIG. 5 is an explanatory diagram showing a cross-sectional configuration of the light emitting element and the light guide configured on the element substrate constituting the organic EL device 70 in the exposure head 10 according to Embodiment 1 of the present invention.

  When the organic EL device 70 described with reference to FIGS. 1 and 2 is configured, in this embodiment, as shown in FIGS. 4A and 4B, the organic EL element 5 as the first light emitting element is X. A plurality of first element substrates 71 arranged in the direction at a constant pitch P and a second element substrate 72 in which a plurality of organic EL elements 5 as second light emitting elements are arranged at a constant pitch P in the X direction It has a structure arranged so as to overlap in the thickness direction. In the first element substrate 71, a substrate body 710 having a substrate thickness of about 0.5 mm is used, and the surface of the substrate body 710 on which the first light emitting element (organic EL element 5) is formed is the first surface. Assuming that the first surface 71a is the second surface 71b and the opposite surface is the second surface 71b, the first element substrate 71 has the first surface 71a on which the organic EL element 5 is formed facing the second element substrate 72. Further, the second element substrate 72 uses a substrate body 720 having a substrate thickness of about 0.5 mm, and the surface of the substrate body 720 on which the second light emitting element (organic EL element 5) is formed. Is the first surface 72a, and the opposite side is the second surface 72b, the second element substrate 72 has the first surface 72a on which the organic EL element 5 is formed facing the first element substrate 71. . In the organic EL device 70 configured as described above, the first element substrate 71 and the second element substrate 72 are configured to be bonded together with a desiccant together with a sealing member.

As shown in FIG. 5, the first light emitting element (organic EL element 5) includes a first electrode 51 serving as an anode (pixel electrode), a light emitting functional layer 52, a first surface 71a of the first element substrate 71, And the 2nd electrode 53 as a cathode has the structure laminated | stacked on the thickness direction in this order. Here, the organic EL element 5 has a substantially rectangular planar shape whose dimension in the Y direction (length dimension) is larger than that in the X direction (width dimension). In this embodiment, the organic EL element 5 has a width dimension of 28 μm and a length dimension of 300 μm. For this reason, the light emitting portion area of the organic EL element 5 (the planar area of the organic EL element 5) is 84 × 10 ⁻⁴ mm ² . In the first element substrate 71, a protective film 62 is formed on the upper side of the second electrode 53. The protective film 62 includes a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon oxynitride film. It consists of a single layer or a composite film. In addition, a partition layer 61 that defines the formation position of the light emitting functional layer 52 and the like is formed on the first surface 71 a of the first element substrate 71 by an acrylic resin, a polyimide resin, or the like, and is a region surrounded by the partition layer 61. A first electrode 51 and a light emitting functional layer 52 are formed therein.

  The light emitting functional layer 52 is a layer responsible for light emission, and may be referred to as a light emitting layer. The light emitting functional layer 52 may include a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, and the like. In this embodiment, the second electrode 53 is formed independently for each organic EL element 5, but the light emitting functional layer 52 and the second electrode 53 are formed on the plurality of first electrodes 51 and the partition layer 61. It may be formed so as to straddle.

  In this embodiment, the organic EL element 5 is a bottom emission type in which light emitted from the light emitting functional layer 52 is emitted from the first electrode 51 side. For this reason, while the 1st electrode 51 is comprised by the translucent electrode, the 2nd electrode 53 is provided with reflective layers, such as aluminum.

  Since the organic EL element 5 formed as the second light emitting element on the second element substrate 72 has the same configuration as the first light emitting element (organic EL element 5), the description of the second light emitting element. Is omitted.

(Configuration of light guide)
In the organic EL device 70 configured as described above, in this embodiment, the light emitted from the organic EL element 5 is applied to the first element substrate 71 on the light emission side of the light from the organic EL element 5. A light guide 4 (first light guide) that exits from an end surface 711 located on one side in the Y direction is formed. Therefore, the organic EL element 5 emits light in a direction perpendicular to the first element substrate 71 and enters the light guide 4 as indicated by an arrow L1 in FIG. As shown in FIG. 2, the light is guided in the Y direction and emitted from the light emitting unit 40 shown in FIGS. 2 and 4 in the Y direction.

  Here, since the organic EL element 5 emits the light emitted from the light emitting functional layer 52 from the first electrode 51 side, the light guide 4 has a side where the light emitting functional layer 52 is located with respect to the first electrode 51. Is formed on the opposite side, that is, between the first electrode 51 and the substrate body 710. As the light guide 4, various configurations can be used. In this embodiment, the light guide 4 receives the light transmitted through the first electrode 51 and totally reflects the light from the core layer 41. A cladding layer 42 for guiding to the end face 711 and a light shielding layer 43 for preventing crosstalk and the like are provided. In the light guide 4, the core layer 41 has a refractive index larger than that of the cladding layer 42 and has a thickness dimension sufficiently larger than the light emission wavelength of the organic EL element 5, and the light guide 4 functions as an optical waveguide. In forming the core layer 41 and the cladding layer 42, an organic material such as polymethyl methacrylate or polystyrene can be used, and an inorganic material such as a silicon oxide film, a silicon nitride film, or a titanium oxide film can be used. Good. Further, if the light shielding layer 43 is made of a reflective metal such as aluminum, the light shielding layer 43 can be constituted as a reflective layer.

  The light guide 4 has a one-to-one relationship with the organic EL element 5 and is formed so as to overlap the organic EL element 5 in plan view. For this reason, the light guide path 4 is also arranged with a constant pitch P in the X direction with respect to the first surface side 71 a side of the first element substrate 71 as in the organic EL element 5. Further, like the organic EL element 5, the light guide 4 has a substantially rectangular planar shape whose dimension in the Y direction (length dimension) is larger than that in the X direction (width dimension).

As shown in FIG. 4C, the light guide 4 extends to the end surface 711 of the first element substrate 71, and the end constitutes the light emitting part 40. On the other hand, the organic EL element 5 only extends to the vicinity of the end face 711 of the first element substrate 71, is not exposed at the end face 711, and is covered with the protective film 62 described above. In this embodiment, the light emitting part 40 has a vertical dimension and a horizontal dimension of 25 μm, and the area of the light emitting part 40 is 6.25 × 10 ⁻⁴ mm ² .

  Further, in the present embodiment, similarly to the first element substrate 71, the light emitted from the organic EL element 5 is also emitted from the organic EL element 5 in the Y direction of the second element substrate 72. A light guide path 4 (second light guide path) that exits from an end surface 721 located on one side is formed. Since the configuration of the light guide path is the same as that of the light guide path formed on the first element substrate 71, description thereof is omitted.

(Position relationship of organic EL element 5)
The first element substrate 71 and the second element substrate 72 configured in this manner are stacked and bonded with an adhesive or the like. The thickness dimension after bonding the first element substrate 71 and the second element substrate 72 is about 1.5 mm. Further, when the first element substrate 71 and the second element substrate 72 are overlapped, the positions of the organic EL elements 5 formed on both are shifted in the X direction. Here, since the pitch of the organic EL elements 5 is constant at P in the first element substrate 71 and the second element substrate 72, the organic EL elements 5 formed on the first element substrate 71 are connected to the second element substrate 72. The first element substrate 71 and the second element substrate 72 are stacked so as to be positioned at the center of the organic EL elements 5 adjacent in the X direction. As a result, the organic EL element 5 formed on the second element substrate 72 is also located at the center of the organic EL elements 5 adjacent in the X direction on the first element substrate 71, so that the first element substrate 71 and the second element In the entire organic EL element 5 formed on the substrate 72, the organic EL elements 5 are all arranged at a P / 2 pitch. Therefore, as shown in FIG. 2B, the light emitting portions 40 are arranged in a staggered manner. Therefore, when the pitch P of the organic EL elements 5 on the first element substrate 71 and the second element substrate 72 is 42.4 μm, all the organic EL elements 5 are 21.2 μm in the entire organic EL element 5. Alternatively, in the first element substrate 71 and the second element substrate 72, the organic EL elements 5 may be formed in advance by shifting by a half pitch, and the element substrates may be bonded together without shifting.

  In this manner, in stacking the first element substrate 71 and the second element substrate 72 in this way, in this embodiment, both end portions of the first element substrate 71 and the second element substrate 72 are utilized by using the manufacturing process of the organic EL element 5 and the like. Are formed with alignment marks 719 and 729. For this reason, the 1st element substrate 71 and the 2nd element substrate 72 can be piled up with high precision.

(Main effects of this form)
As described above, in the exposure head 10 (light source device) of the present embodiment, the organic EL element 5 (light emitting element) as the light source is placed in the X direction on the element substrate (first element substrate 71 and second element substrate 72). A plurality of such organic EL elements 5 are provided with a first electrode 51, a light emitting functional layer 52, and a second electrode 53 stacked in the thickness direction of the element substrate. For this reason, the organic EL element 5 emits light in the normal direction of the substrate surface of the element substrate. Further, on the element substrates (first element substrate 71 and second element substrate 72), the light emitted from the organic EL element 5 is positioned on one side of the element substrate in the Y direction with respect to the organic EL element 5. Since the light guide path 4 that exits from the end faces (the end face 711 of the first element substrate 71 and the end face 721 of the second element substrate 72) is formed, the light emitted from the organic EL element 5 is reflected on the end face 711 of the element substrate, 712 is emitted. For this reason, the area of the light extraction part (light emitting part 40) is smaller than the actual light emitting part area of the organic EL element 5. For example, the actual light emitting area of the organic EL element 5 (the planar area of the organic EL element 5) is 84 × 10 ⁻⁴ mm ² , but the area of the light emitting portion 40 is 6.25 × 10 ⁻⁴ mm ² . is there. For this reason, it is possible to emit light having a high directivity and a power density of about 10 times without imposing a large burden on the organic EL element 5. Therefore, the reliability of the exposure head 10 can be improved. Furthermore, in this embodiment, a first element substrate 71 in which a plurality of organic EL elements 5 (first light emitting elements) are arranged in the X direction, and a first element substrate 71 in which a plurality of organic EL elements 5 (second light emitting elements) are arranged in the X direction. Since it has a structure in which the two-element substrate 72 is overlapped in the thickness direction, the organic EL element can be used even when the light emitted from the organic EL element 5 is emitted from the end surfaces 711 and 721 of the element substrate. The elements 5 can be arranged at a high density of 2400 dpi.

  In the exposure head 10 (light source device) of the present embodiment, the organic EL element 5 formed on the first element substrate 71 and the organic EL element 5 formed on the second element substrate 72 are in a position shifted in the X direction. . For this reason, the organic EL elements 5 can be arranged with high density in the X direction. In particular, in this embodiment, the organic EL element 5 formed on the first element substrate 71 and the organic EL element 5 formed on the second element substrate 72 are at positions shifted in the X direction by a half pitch (P / 2). Therefore, the organic EL element 5 as a whole can have a configuration in which the organic EL elements 5 are all arranged at a P / 2 pitch in the X direction.

  Furthermore, in this embodiment, since the light guide 4 is integrally formed on each of the first element substrate 71 and the second element substrate 72, the light guide 4 and the organic EL element 5 can be arranged with high positional accuracy. it can.

  Furthermore, since the first element substrate 71 and the second element substrate 72 are stacked so that the first surfaces 71a and 72b on which the organic EL element 5 is formed face each other, the organic EL element 5 is exposed to the outside. The area to be exposed is small. Therefore, the organic EL element 5 can be reliably and easily sealed, and the reliability of the exposure head 10 can be improved with a relatively inexpensive sealing structure.

[Embodiment 2]
FIG. 6 is an explanatory diagram of the organic EL device 70 used in the exposure head 10 according to the second embodiment of the present invention. FIGS. 6 (a), 6 (b), and 6 (c) show the organic EL device 70 as a light beam. FIG. 3 is an explanatory diagram viewed from the emission unit 40 side, an explanatory diagram showing a state where the organic EL device 70 is disassembled into a first element substrate 71 and a second element substrate 72, and an explanatory diagram showing a planar configuration of the element substrate. . FIG. 7 is an explanatory diagram showing a cross-sectional configuration of a light emitting element (organic EL element 5) and a light guide path 4 configured on an element substrate constituting the organic EL device 70 in the exposure head 10 according to Embodiment 2 of the present invention. is there. Since the basic configuration of this embodiment is the same as that of Embodiment 1, common portions are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIGS. 6 and 7, in this embodiment as well, in the case of configuring the organic EL device 70 used in the exposure head 10 (light source device), the organic EL element 5 as the first light emitting element is the same as in the first embodiment. A first element substrate 71 in which a plurality of elements are arranged at a constant pitch P in the X direction, and a second element substrate 72 in which a plurality of organic EL elements 5 as second light emitting elements are arranged at a constant pitch P in the X direction, It has a structure in which the substrates are stacked in the thickness direction.

  In carrying out such superposition, in the first embodiment, the first surface 71a side where the organic EL element 5 is formed on the first element substrate 71 and the organic EL element 5) are formed on the second element substrate 72. The first surface 72a side is overlapped. On the other hand, in this embodiment, the second surfaces 71b and 72b opposite to the first surfaces 71a and 72a on which the organic EL element 5 is formed are overlapped.

  Here, as in the first embodiment, the organic EL element 5 has a structure in which the first electrode 51 as the anode, the light emitting functional layer 52, and the second electrode 53 as the cathode are stacked in this order in the thickness direction. A protective film 62 is formed on the upper layer side of the second electrode 53.

  Similarly to the first embodiment, the first element substrate 71 and the second element substrate 72 include the organic EL element 5 on the side opposite to the side where the light emitting functional layer 52 is located with respect to the first electrode 51. A light guide path 4 is formed through which the emitted light is emitted from end surfaces 711 and 721 located on one side of the first element substrate 71 and the second element substrate 72 in the Y direction. Further, when the first element substrate 71 and the second element substrate 72 are overlapped, the positions of the organic EL elements 5 formed on both are shifted by a half pitch in the X direction. Accordingly, in this embodiment as well, as in the first embodiment, the area of the light extraction portion (light emitting portion 40) is smaller than the actual light emitting portion area of the organic EL element 5, so that a large burden is not imposed on the organic EL element 5. It is possible to emit light having high power density and high directivity. Further, even when a method of emitting light emitted from the organic EL element 5 from the end surfaces 711 and 721 of the element substrate is adopted, the organic EL element 5 can be arranged at a high density, etc. The effect is almost the same.

[Embodiment 3]
FIG. 8 is an explanatory view showing a cross-sectional configuration of the light emitting element (organic EL element 5) and the light guide path 4 configured on the element substrate constituting the organic EL device 70 in the exposure head 10 according to Embodiment 3 of the present invention. is there. Since the basic configuration of this embodiment is the same as that of Embodiments 1 and 2, common portions are denoted by the same reference numerals and description thereof is omitted. Further, FIG. 4 referred to in the first embodiment and FIG. 6 referred to in the second embodiment are used to describe the entire exposure head 10 (light source device).

  As shown in FIGS. 4 and 6, in this embodiment as well, in the case of configuring the organic EL device 70 used in the exposure head 10 (light source device), the organic EL element as the first light emitting element is the same as in the first and second embodiments. A first element substrate 71 in which a plurality of elements 5 are arranged at a constant pitch P in the X direction; a second element substrate 72 in which a plurality of organic EL elements 5 as second light emitting elements are arranged at a constant pitch P in the X direction; However, it has the structure arrange | positioned so that it might overlap in the thickness direction of a board | substrate. Further, when the first element substrate 71 and the second element substrate 72 are overlapped, the positions of the organic EL elements 5 formed on both are shifted by a half pitch in the X direction.

  As shown in FIG. 8, also in this embodiment, the organic EL element 5 includes the first electrode 51 as the anode, the light emitting functional layer 52, and the second electrode 53 as the cathode in this order, as in the first and second embodiments. The structure is laminated in the thickness direction, and a protective film 62 is formed on the upper layer side of the second electrode 53. In the organic EL element 5, in Embodiments 1 and 2, the light generated in the light emitting functional layer 52 is emitted from the first electrode 51 side, but in this embodiment, the light generated in the light emitting functional layer 52 is second. The light is emitted from the electrode 53 side. Therefore, the second electrode 53 is formed of a light-transmitting cathode layer, and a reflective layer (not shown) is provided on the opposite side of the first electrode 51 from the side where the light emitting functional layer 52 is located. Yes.

  Thus, in this embodiment, the organic EL element 5 emits light from the second electrode 53 side. Therefore, in this embodiment, the organic EL element 5 is emitted to the first element substrate 71 and the second element substrate 72 on the side opposite to the side where the light emitting functional layer 52 is located with respect to the second electrode 53. A light guide path 4 is formed through which light is emitted from end surfaces 711 and 721 located on one side in the Y direction of the first element substrate 71 and the second element substrate 72.

  When the first element substrate 71 and the second element substrate 72 configured as described above are overlapped, the organic EL element 5 is formed on the first element substrate 71 as described with reference to FIG. A configuration in which the first surface 71a side and the first surface 72a side on which the organic EL element 5 is formed on the second element substrate 72 may be employed. In addition, as described with reference to FIG. 6, the second surface 71 b opposite to the first surfaces 71 a and 72 a on which the organic EL elements 5 are formed in the first element substrate 71 and the second element substrate 72, 72b may be overlapped.

  In either case, the area of the light extraction part (light emitting part 40) is smaller than the actual light emitting part area of the organic EL element 5 as in the first and second embodiments. Thus, light with high power density and high directivity can be emitted. In addition, even when a method of emitting light emitted from the organic EL element 5 from the end surfaces 711 and 721 of the element substrate is employed, the organic EL element 5 can be arranged with high density.

[Embodiment 4]
FIG. 9 is an explanatory diagram showing a cross-sectional configuration of the light emitting element (organic EL element 5) and the light guide path 4 configured on the element substrate constituting the organic EL device 70 in the exposure head 10 according to Embodiment 4 of the present invention. is there. Since the basic configuration of this embodiment is the same as that of Embodiments 1 and 2, common portions are denoted by the same reference numerals and description thereof is omitted. Further, FIG. 4 referred to in the first embodiment and FIG. 6 referred to in the second embodiment are used to describe the entire exposure head 10 (light source device).

  As shown in FIGS. 4 and 6, in this embodiment as well, in the case of configuring the organic EL device 70 used in the exposure head 10 (light source device), the organic EL element as the first light emitting element is the same as in the first and second embodiments. A first element substrate 71 in which a plurality of elements 5 are arranged at a constant pitch P in the X direction; a second element substrate 72 in which a plurality of organic EL elements 5 as second light emitting elements are arranged at a constant pitch P in the X direction; However, it has the structure arrange | positioned so that it might overlap in the thickness direction of a board | substrate. Further, when the first element substrate 71 and the second element substrate 72 are overlapped, the positions of the organic EL elements 5 formed on both are shifted by a half pitch in the X direction.

  As shown in FIG. 9, also in this embodiment, as in Embodiments 1 and 2, the organic EL element 5 includes a first electrode 51 as an anode, a light emitting functional layer 52, and a second electrode 53 as a cathode in this order. The structure is laminated in the thickness direction, and a protective film 62 is formed on the upper layer side of the second electrode 53. In the organic EL element 5, also in this embodiment, the light generated in the light emitting functional layer 52 is emitted from the first electrode 51 side in the first and second embodiments.

  Here, in the first and second embodiments, the light guide 4 is formed between the organic EL element 5 and the substrate bodies 710 and 720. On the other hand, in this embodiment, the light guide 4 is formed on the opposite side of the substrate main bodies 710 and 720 from the side where the organic EL element 5 is located.

  When the first element substrate 71 and the second element substrate 72 configured as described above are overlapped, the organic EL element 5 is formed on the first element substrate 71 as described with reference to FIG. A configuration in which the first surface 71a side and the first surface 72a side on which the organic EL element 5 is formed on the second element substrate 72 may be employed. In addition, as described with reference to FIG. 6, the second surface 71 b opposite to the first surfaces 71 a and 72 a on which the organic EL elements 5 are formed in the first element substrate 71 and the second element substrate 72, You may overlap so that 72b may oppose.

  In any case, since the area of the light extraction part (light emitting part 40) is smaller than the actual light emitting part area of the organic EL element 5 as in the first and second embodiments, a large burden is not imposed on the organic EL element 5. Thus, light with high power density and high directivity can be emitted. In addition, even when a method of emitting light emitted from the organic EL element 5 from the end surfaces 711 and 721 of the element substrate is employed, the organic EL element 5 can be arranged with high density.

[Embodiment 5]
FIG. 10 is an explanatory diagram showing a cross-sectional configuration of the light emitting element (organic EL element 5) and the light guide path 4 configured on the element substrate constituting the organic EL device 70 in the exposure head 10 according to Embodiment 5 of the present invention. is there. Since the basic configuration of this embodiment is the same as that of Embodiment 1, common portions are denoted by the same reference numerals, and description thereof is omitted. Further, FIG. 4 referred to in the first embodiment is used to describe the entire exposure head 10 (light source device).

  As shown in FIG. 4, in this embodiment as well, in the case of configuring the organic EL device 70 used for the exposure head 10 (light source device), the organic EL element 5 as the first light emitting element is arranged in the X direction as in the first embodiment. The first element substrate 71 in which a plurality of elements are arranged at a constant pitch P and the second element substrate 72 in which a plurality of organic EL elements 5 as second light emitting elements are arranged at a constant pitch P in the X direction are the thickness of the substrate. It has a structure arranged in the vertical direction. Further, when the first element substrate 71 and the second element substrate 72 are overlapped, the positions of the organic EL elements 5 formed on both are shifted by a half pitch in the X direction.

  As shown in FIG. 10, also in this embodiment, the organic EL element 5 includes the first electrode 51 as the anode, the light emitting functional layer 52, and the second electrode 53 as the cathode in this order, as in the first embodiment. The protective layer 62 is formed on the upper layer side of the second electrode 53. In such an organic EL element 5, also in this embodiment, the light generated in the light emitting functional layer 52 is emitted from the first electrode 51 side in the first embodiment. For this reason, the light guide 4 is formed between the organic EL element 5 and the substrate bodies 710 and 720. Here, in both the first element substrate 71 and the second element substrate 72, the light guide path 4 is opposite to one side + Y in the Y direction where the light emitting portion 40 described with reference to FIG. The cross-sectional area increases from the other side −Y to the one side + Y. More specifically, the thickness dimension t of the core layer 41 constituting the light guide 4 increases from the other side −Y in the Y direction toward the one side + Y. For this reason, the interface between the core layer 41 and the clad layer 42 is a tapered surface inclined obliquely from the other side −Y to the one side + Y.

  For this reason, since the light generated on the other side −Y in the organic EL element 5 can be efficiently guided toward the one side + Y, the light emission efficiency can be improved.

  In addition, although the example which employ | adopted the characteristic part of this form in Embodiment 1 is represented in FIG. 10, the characteristic part (structure of the light guide 4) of this form is employ | adopted in Embodiment 2-4. Also good.

[Other embodiments]
In the first to fifth embodiments, each of the plurality of light emitting units 40 may be provided with a microlens. For such a configuration, for example, a microlens array including a plurality of microlenses is used as the light emission of the organic EL device 70. It can be realized by bonding to the end face.

  In the first to fourth embodiments, the light guide 4 is formed integrally with the first element substrate 71 and the second element substrate 72, but a sheet-like member different from the first element substrate 71 and the second element substrate 72. Alternatively, the light guide 4 may be formed on the substrate to form a light guide member, and the light guide member may be bonded to the first element substrate 71 and the second element substrate 72.

  In the above embodiment, the organic EL element 5 is used as a light-emitting element that constitutes a light source. Can be applied.

  In the above embodiment, the present invention is applied to the exposure head 10 (light source device). However, the present invention is applied to a light source device other than the exposure head 10 of the image forming apparatus 100, such as a light source device used as an illumination device. The present invention may be applied.

[Entire configuration of image forming apparatus]
With reference to FIG. 11 and FIG. 12, the overall configuration of an image forming apparatus to which the present invention is applied will be described. 11 and 12 are a longitudinal sectional view showing the overall configuration of an image forming apparatus to which the present invention is applied, and a longitudinal sectional view showing the overall configuration of another image forming apparatus to which the present invention is applied.

(Configuration example 1 of image forming apparatus)
An image forming apparatus 100 shown in FIG. 11 is a tandem-type full-color image forming apparatus using a belt intermediate transfer body method. In this image forming apparatus 100, four exposure heads 10K, 10C, 10M, and 10Y are arranged at exposure positions of four photosensitive drums (image carriers) 110K, 110C, 110M, and 110Y, respectively. The exposure heads 10K, 10C, 10M, and 10Y are the exposure heads 10 according to the above embodiments.

  The image forming apparatus 100 is provided with a driving roller 121 and a driven roller 122, and an endless intermediate transfer belt 120 is wound around these rollers 121 and 122, and the rollers 121 and 122 are indicated by arrows. Can be rotated around. Although not shown, tension applying means such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

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

  Around each photosensitive drum 110 (K, C, M, Y), a corona charger 111 (K, C, M, Y), an exposure head 10 (exposure heads 10K, C, M, Y), Developing units 114 (K, C, M, Y) are arranged. The corona charger 111 (K, C, M, Y) uniformly charges the outer peripheral surface of the corresponding photosensitive drum 110 (K, C, M, Y). The exposure head 10 (exposure heads 10K, C, M, Y) writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum. Each exposure head 10 (K, C, M, Y) is installed such that a plurality of organic EL elements 5 are arranged along the bus (main scanning direction) of the photosensitive drum 110 (K, C, M, Y). Is done. The electrostatic latent image is written by irradiating the photosensitive drum with light by a plurality of light emitting elements (organic EL elements 5). The developing device 114 (K, C, M, Y) forms a visible image, ie, a visible image, on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

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

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

(Configuration example 2 of image forming apparatus)
An image forming apparatus 100 shown in FIG. 12 is a rotary developing type full-color image forming apparatus using a belt intermediate transfer body system, and a corona charger 168, a rotary type developing unit 161, and the like around a photosensitive drum 165. An exposure head 167 and an intermediate transfer belt 169 are provided.

  The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. The exposure head 167 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. The exposure head 167 is the exposure head 10 according to the above embodiment.

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

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

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

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

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

(Other configuration examples)
Note that the light source device of the present invention can also be employed in electrophotographic image forming apparatuses other than those exemplified above. For example, the light emitting device according to the present invention is applied to an image forming apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, and an image forming apparatus that forms a monochrome image. Is possible.

4 .... Light guide path, 5 .... Organic EL element (organic electroluminescence element / light emitting element), 10..Exposure head (light source device), 40..Light emitting part, 51..First electrode, 52..Light emission Functional layer 53 second electrode 70 organic EL device 71 first element substrate 72 second element substrate 110 photosensitive drum 110s image bearing surface 100 Image forming apparatus

Claims (8)

A light source device using a light emitting element in which a first electrode, a light emitting functional layer, and a second electrode are stacked in a thickness direction of an element substrate as a light source, wherein the directions intersecting each other in the in-plane direction of the element substrate are X direction and Y When the direction
A first element substrate in which a plurality of first light emitting elements are arranged in the X direction;
A first light guide that emits light emitted from the first light emitting element from an end surface located on one side in the Y direction of the first element substrate;
A second element substrate in which a plurality of second light emitting elements are arranged in the X direction, and are arranged so as to overlap the first element substrate in the thickness direction;
A second light guide path for emitting light emitted from the second light emitting element from an end face located on the one side in the Y direction of the second element substrate;
A light source device characterized by comprising:   The light source device according to claim 1, wherein the first light emitting element and the second light emitting element are provided at positions shifted in the X direction. The first light emitting elements are provided at equal intervals in the X direction,
The second light emitting elements are provided at equal intervals in the X direction with the same interval as the first light emitting element.
3. The light source device according to claim 2, wherein in the X direction, the first light emitting element is provided at a central position between two second light emitting elements adjacent in the X direction.   4. The length of the first light-emitting element and the second light-emitting element in the Y direction is larger than the width dimension in the X direction. 5. Light source device.   5. The cross-sectional area of the first light guide path and the second light guide path is increased from the other side opposite to the one side in the Y direction toward the one side. The light source device according to any one of the above.   6. The first light guide path is formed integrally with the first element substrate, and the second light guide path is formed integrally with the second element substrate. The light source device according to 1.   The light source device according to claim 1, wherein the first light emitting element and the second light emitting element are organic electroluminescent elements. An image forming apparatus comprising the light source device according to any one of claims 1 to 7 as an exposure head,
An image forming apparatus comprising an image carrier on which a latent image is formed by light emitted from the light emitting element.

Images