JP2007283546A - Exposure system and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently improve fineness of a spot region on an exposure face. <P>SOLUTION: This exposure system H comprises a light emitting device 10 having a plurality of light emitting elements E arranged therein, a collimating lens array 30 for collimating the emission light from each light emitting element E, and a light blocking body 44 having an opening section A2 for passing the emission light from the collimating lens array 30 therethrough. A light transmitting body 42 made of a transparent plate material is disposed on a portion at the opposite side of the light emitting device 10 with respect to the collimating lens array 30. The light blocking body 44 is formed on the surface of the light transmitting body 42 at the opposite side of the collimating lens array 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an exposure apparatus including a plurality of light emitting elements and an image forming apparatus using the exposure apparatus.

2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has been proposed in which a light emitting device in which light emitting elements such as organic light emitting diode elements are arranged on the surface of a substrate is used for exposure of an image carrier (for example, a photosensitive drum). Patent Document 1 discloses a configuration in which a light shielding layer in which an opening (aperture) is formed at a portion facing each light source is provided on the surface of the substrate. Of the light emitted from the light source, only the component that has passed through the opening reaches the image carrier.
JP-A-6-262803

However, since the light beam that has passed through the opening under the configuration of Patent Document 1 travels while diffusing, particularly in the configuration in which the image carrier and the light emitting device are separated from each other, light emission from one of the surfaces of the image carrier is performed. It is difficult to sufficiently miniaturize the spot area (and further increase the image definition) where the light emitted from the element reaches. Although a configuration in which a lens for condensing the light emitted from each light emitting element is arranged in the gap between the light emitting device and the image carrier, the light emitted from many light emitting elements is imaged in a sufficiently fine spot area. Adopting a high-performance lens is not always easy from the viewpoint of cost. In view of such circumstances, an object of the present invention is to solve the problem of sufficiently miniaturizing a spot region.

In order to solve this problem, an exposure apparatus according to the present invention includes a light emitting device in which a plurality of light emitting elements are arranged, and a condenser (for example, a converging lens in FIG. 4) that condenses light emitted from each light emitting element. And an array 30) and a first light-blocking body (for example, the light-blocking body 44 in FIG. 4) in which a plurality of openings (for example, the opening A2 in FIG. 4) through which light emitted from the light collector passes is formed. In the present invention, since the luminous flux width of the light emitted from the condenser is reduced by the first light shield, the spot area on the surface of the object exposed by the exposure apparatus (hereinafter referred to as “exposure surface”) is sufficiently miniaturized. Is possible.

In a preferred aspect of the present invention, each opening of the first light shield overlaps each of the plurality of light emitting elements as viewed from the direction of the optical axis of the light collector (for example, the Z direction in FIG. 4). According to this aspect, since the light emitted from the light emitting element reaches the opening with high efficiency, it is possible to sufficiently secure the energy density on the exposure surface. Further, if each opening of the first light shielding body is smaller than the area of the light emitting element (in other words, the area of the spot area required on the exposure surface in design), the spot area on the exposure surface is further miniaturized. Is done.

In a more preferred aspect, the light emitting device includes a second light shielding body (for example, the light shielding layer 16 in FIG. 4) in which a plurality of openings (for example, the opening A1 in FIG. 4) through which light emitted from the light emitting element passes is formed. The condensing body condenses light transmitted through each opening of the second light shielding body. According to this aspect, there is an advantage that diffusion of emitted light from each light emitting element toward the light collector is suppressed.

An exposure apparatus according to a preferred aspect of the present invention includes a first light-transmitting body (for example, the light-transmitting body 42 in FIG. 4) disposed on the side opposite to the light-emitting device with the light collector interposed therebetween, and the first light-shielding device. The body is fixed to the surface of the first light transmitting body on the side opposite to the light collecting body. According to this aspect, it is possible to suppress the deformation of the first light shielding body while ensuring a sufficient ratio of the amount of light passing through the opening portion of the emitted light of the light collecting body by making the first light shielding body thinner. . Furthermore, the first light shielding body can be easily and sufficiently brought close to the exposure surface according to the thickness of the first light transmitting body.

In a more specific aspect, the surface of the first light transmissive body that faces the light collector is in close contact with the light collector. According to this aspect, reflection and refraction of light on the surface of the first translucent body facing the light collector is suppressed. “Close contact” means that no air layer is interposed between the first light transmitting body and the light collecting body. Therefore, in addition to the configuration in which the first light transmitting body is in direct contact with the light collector,
The configuration in which the first light-transmitting body is in proximity to the light collector indirectly through another member or adhesive is also referred to in the present invention.
It is included in the concept of “contact”. For example, a configuration in which a refractive index matching liquid having a refractive index equivalent to that of the first light transmitting body is filled between the light collecting body and the first light transmitting body is employed. According to this configuration, the first light transmitting body (
The reflection and refraction of light in the gap between the first light transmitting body and the light collecting body is effectively suppressed while the relative position between the first light shielding body) and the light emitting device or the light collecting body can be adjusted. .

Moreover, the structure by which the antireflection process (For example, the process which forms the AR coat layer 46 of FIG. 4) was given to the surface on the opposite side to a condensing body among 1st translucent bodies is also employ | adopted. According to this configuration, since the reflection of light on the surface of the first light transmitting body opposite to the light collecting body is suppressed, the light emitted from the light collecting body passes through the opening of the first light shielding body. Thus, it is possible to secure a sufficient ratio of the amount of light reaching the exposure surface.

An exposure apparatus according to a preferred aspect of the present invention includes a second light-transmitting body (for example, the light-transmitting body 36 in FIG. 6) on which light emitted from each light-emitting element enters, and the light collecting body includes a second light-transmitting body. The light emitted from each light emitting element that is disposed on the opposite side of the light emitting device with the body interposed therebetween and transmitted through the second light transmitting body is collected. According to this aspect, since the second light transmitting body is inserted in the gap between the light emitting device and the light collecting body, reflection on the surface on the light collecting body side of the light emitting device or on the surface on the light emitting device side of the light collecting body. It is suppressed. Therefore, it is possible to increase the ratio of the amount of light incident on the light collector from the light emitted from the light emitting element.

The image forming apparatus according to the present invention exposes an image carrier with an image carrier (for example, the photosensitive drum 70 in FIG. 1) on which a latent image is formed by exposure and light beams that have passed through the openings of the first light shield. The exposure apparatus of the present invention, and a developing unit for forming a visible image by adding a developer to the latent image formed on the image carrier. According to the exposure apparatus of the present invention, since the spot area on the surface of the image carrier is miniaturized, the image forming apparatus can form a high-definition image. In particular, according to the configuration in which the distance between the surface of the first light-shielding member facing the image carrier and the image forming surface of the image carrier is 0.3 mm or less (more preferably 0.1 mm or less), It is possible to define the form (size / shape) of the spot area on the surface with high accuracy according to the form of the opening of the first light shield.

<A: First Embodiment>
FIG. 1 is a perspective view showing a partial configuration of the image forming apparatus according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. As shown in FIG. 1 and FIG.
The image forming apparatus includes a photosensitive drum 70 on which a latent image is formed on a surface (hereinafter referred to as “image forming surface”) 72 by exposure and an exposure device (line head) H that exposes the image forming surface 72.
The photosensitive drum 70 is supported by a rotation shaft extending in the X direction (main scanning direction), and an image forming surface 72.
It rotates with the (outer peripheral surface) facing the exposure apparatus H.

As shown in FIGS. 1 and 2, the exposure apparatus H includes a light emitting device 10 and a converging lens array 30.
And the light flux restricting body 40. The converging lens array 30 includes a light emitting device 10 and a photosensitive drum 70.
It is arranged in the gap. The light flux restricting body 40 has the light-emitting device 1 sandwiching the converging lens array 30.
It is arranged on the side opposite to 0 (the gap between the focusing lens array 30 and the photosensitive drum 70). The light emitted from the exposure apparatus H passes through the converging lens array 30 and the light beam restricting body 40 and reaches the image forming surface 72 of the photosensitive drum 70.

3 is a plan view showing the structure of the exposure apparatus H when viewed from the photosensitive drum 70 side, and FIG. 4 is a cross-sectional view (enlarged view of FIG. 2) taken along line IV-IV in FIG. As shown in FIG. 1 to FIG. 4, the light emitting device 10 includes a rectangular substrate 12 fixed in a posture in which the X direction is a longitudinal direction, and a plurality of light emitting elements E arranged on the surface of the substrate 12. . The substrate 12 is a light transmissive plate material formed of glass or plastic. Each light emitting element E is an organic light emitting diode element that emits light when supplied with current. As shown in FIG. 3, the plurality of light emitting elements E are arranged in two rows and zigzag along the X direction. However, the arrangement pattern of the light emitting elements E in the present invention is arbitrary.

Next, a specific structure of the light emitting device 10 will be described with reference to FIG. As shown in the figure, a wiring layer 14 is formed on the surface of the substrate 12 opposite to the photosensitive drum 70. Wiring layer 1
Reference numeral 4 denotes a portion in which an active element (for example, a transistor) that controls the luminance of the light-emitting element E, a conductive layer such as a wiring or power supply line that transmits various signals, and an insulating layer that insulates each element are stacked.
On the surface of the wiring layer 14, a first electrode 21 that functions as an anode of the light emitting element E is formed separately for each light emitting element E. As the material of the first electrode 21, a light transmissive conductive material such as ITO (Indium Tin Oxide) is employed.

An insulating layer 23 is formed on the surface of the wiring layer 14 on which the first electrode 21 is formed. Insulating layer 23
Is an insulating film body in which an opening 231 is formed in each region overlapping the first electrode 21.
The light emitting layer 25 made of an organic EL (ElectroLuminescent) material includes the first electrode 21 and the insulating layer 2.
3 is formed continuously over a plurality of light emitting elements E so as to cover 3. Since the first electrode 21 is formed separately for each light emitting element E, the luminance of the light emitting layer 25 depends on the voltage of each first electrode 21 even though the light emitting layer 25 is continuous over the plurality of light emitting elements E. Each light emitting element E is individually controlled. The surface of the light emitting layer 25 is covered with the second electrode 27. The second electrode 27 is a light-reflective conductive film that continues over the plurality of light-emitting elements E. A portion where the first electrode 21 and the second electrode 27 face each other with the light emitting layer 25 in between (a portion inside the opening 231) functions as the light emitting element E.

As shown in FIG. 4, the wiring layer 14 includes a light shielding layer 16 formed of a light shielding material. A substantially circular opening A1 is formed in a portion of the light shielding layer 16 that overlaps the light emitting element E when viewed from the Z direction. Therefore, only the component that has passed through the opening A1 out of the light emitted from the light emitting layer 25 toward the first electrode 21 and the light reflected from the surface of the second electrode 27 selectively passes through the substrate 12 and passes through the substrate 12. The light is emitted to the outside, and the other components are shielded (absorbed or reflected) by the light shielding layer 16. As shown in FIGS. 3 and 4, the shape of the opening A1 viewed from the Z direction is a substantially circular shape having a diameter d1.
In addition, the light shielding layer 16 may be configured by each wiring configuring the wiring layer 14. The opening A1 may have a shape other than a circle (for example, a quadrangle).

The converging lens array 30 shown in FIGS. 1 and 2 collects light emitted from each light emitting element E (
(Condenser). The converging lens array 30 of the present embodiment is an erecting equal-magnification imaging element that forms an equal-magnification erect image corresponding to the light emitted from each light-emitting element E on the image forming surface 72, as shown in FIG. Thus, a plurality of gradient index lenses 34 are arranged so that the respective central axes (optical axes) are arranged in the Z direction. Each refractive index distribution type lens 34 is a cylindrical member in which the refractive index is distributed in the cross section so that the refractive index becomes lower as the distance from the central axis (optical axis) toward the periphery increases. As the converging lens array 30, for example, there is SLA (selfoc lens array) available from Nippon Sheet Glass Co., Ltd. “SELFOC / SELFOC” is a registered trademark of Nippon Sheet Glass Co., Ltd.

By the way, as a means for condensing the emitted light from each light emitting element E, for example, a microlens array in which a large number of convex lenses corresponding to each light emitting element E are arranged in an array can be adopted. However, since the center axis of each light emitting element E is matched with the optical axis of the convex lens, there is a problem that adjustment of the position of the microlens array with respect to the light emitting device 10 requires extremely high accuracy and the manufacturing cost increases. . In contrast, the converging lens array 30 according to the present embodiment has an advantage that high accuracy is not required for the arrangement. However, in the case where the converging lens array 30 is employed, compared to the microlens array, the spot area on the image forming surface 72 (the intensity at which the emitted light from one light emitting element E of the image forming surface 72 exceeds a predetermined value). In some cases, it is not possible to sufficiently miniaturize the area reached by.

Therefore, in the present embodiment, the light flux width of the emitted light from the converging lens array 30 is restricted (reduced) by the light flux restricting body 40 disposed in the gap between the converging lens array 30 and the photosensitive drum 70. As shown in FIGS. 2 to 4, the light flux restricting body 40 includes a light transmitting body 42 and a light shielding body 4.
4 and an AR (Anti Reflection) coat layer 46. The light transmitting body 42 is a light transmissive flat plate (for example, a glass substrate) disposed on the opposite side of the light emitting device 10 with the converging lens array 30 interposed therebetween. For example, B270 provided by Schott is suitably used as the translucent body 42.

As shown in FIG. 4, the surface of the transparent body 42 facing the converging lens array 30 (hereinafter referred to as “first”).
421) and the end surface on the light exit side of the converging lens array 30 (hereinafter referred to as “light exit surface”).
31) is in close contact with the refractive index matching liquid 54 filled therebetween. That is,
The first surface 421 and the light exit surface 31 are not joined. The refractive index matching liquid 54 has a refractive index of the transparent body 42.
It is a viscous fluid (index matching oil) that is equivalent to Therefore, the light emitted from the light exit surface 31 of the converging lens array 30 enters the translucent body 42 without being reflected or refracted at the interface between the refractive index matching liquid 54 and the first surface 421. The refractive index of the refractive index matching liquid 54 may be equal to that of the converging lens array 30.

As shown in FIG. 1, the image forming apparatus includes an adjustment mechanism 50. The adjusting mechanism 50 is a means for adjusting the relative position of the light transmitting body 42 with respect to the converging lens array 30 and the light emitting device 10. The adjustment mechanism 50 according to the present embodiment includes a plurality of screws whose tips are in contact with the side surfaces of the light transmitting body 42. By rotating or moving each screw closer to or away from the light transmitting body 42, the light transmitting body 42 moves while being in close contact with the light exit surface 31 of the converging lens array 30, so that the light flux to the converging lens array 30 and the light emitting device 10. The position of the regulating body 40 in the XY plane is adjusted.

The light shielding body 44 is a light shielding film body formed on a surface (hereinafter referred to as “second surface”) 422 of the light transmitting body 42 facing the photosensitive drum 70. As shown in FIGS. 2 to 4, the light shielding body 44 is formed with a plurality (the same number as the light emitting elements E) of openings A <b> 2 each corresponding to a separate light emitting element E. Each opening A2 is a small hole (aperture) that penetrates the light shield 44 in the thickness direction. As shown in FIG. 3, one opening A2 is formed in a portion of the light shield 44 that overlaps with the light emitting element E (opening A1) corresponding to the opening A2 when viewed from the Z direction. Therefore, the plurality of openings A2 are arranged in two rows and zigzag along the X direction. The shape of the opening A2 viewed from the Z direction is preferably similar to the shape of the light emitting element E (opening A1).

For example, the light shielding body 44 selectively removes a region corresponding to each opening A2 from the light shielding film body formed over the entire second surface 422 of the translucent body 42 by a photolithography technique or an etching technique. It is formed by doing. As a material of the light shielding body 44, for example, a resin material in which carbon black is dispersed, or a metal material having a low reflectance such as chromium is suitably employed.

The outer shape of each opening A2 is a substantially circular shape in which the diameter d2 is smaller than the diameter d1 of the opening A1 (or the diameter of the light emitting element E). From another viewpoint, the size of the opening A2 is slightly smaller than the spot area required for the image forming surface 72 (designed spot area size). For example, if a spot area with a circular shape of 70 μm is required, the opening A 2
Is a regular circle with a diameter of 68 μm. Further, when a rectangular spot area of 50 μm long × 70 μm wide is required, the opening A2 has a rectangular shape of 49 μm long × 68 μm wide. More specifically, the size of the opening A2 is selected according to the distance between the surface of the light shield 44 and the image forming surface 72. For example, when the distance between the light shield 44 and the image forming surface 72 is short, the section in which the light beam that has passed through the opening A2 diffuses before reaching the image forming surface 72 is shortened. Close dimensions may be used. Conversely, when the distance between the light shield 44 and the image forming surface 72 is short, the light flux that has passed through the aperture A2 is diffused before reaching the image forming surface 72, and the size of the spot area is enlarged (blurred). The opening A2 is set to a size smaller than the design value.

As shown in FIGS. 3 and 4, the position of the light transmitting body 42 in the XY plane (the light emitting device 10).
Is adjusted by the adjusting mechanism 50 so that the center of the opening A1 and the center of the opening A2 substantially coincide with each other when viewed from the Z direction. Therefore, when viewed from the Z direction as shown in FIG. 3, the inner peripheral edge of the opening A2 is located inside the inner peripheral edge of the opening A1 over the entire periphery. In the above configuration, only the component that has passed through the opening A2 corresponding to the light emitting element E out of the light emitted from each light emitting element E that has passed through the light transmitting body 42 and reached the second surface 422 is exposed from the exposure apparatus H. The light is emitted and reaches the photosensitive drum 70, and the other components are blocked (absorbed or reflected) by the light blocking body 44.

The AR coating layer 46 is formed by an antireflection treatment for suppressing light reflection on the second surface 422. As shown in FIGS. 2 to 4, the entire area of the second surface 422 on which the light blocking member 44 is formed is formed. Cover. The AR coating layer 46 of the present embodiment has a structure in which a plurality of light transmission layers having different refractive indexes are stacked. As shown in FIG. 2, the light flux restricting body 40 is disposed so that the surface of the AR coating layer 46 faces the image forming surface 72 of the photosensitive drum 70 with a space therebetween. As described above, according to the configuration in which the AR coating layer 46 is provided, it is possible to secure a sufficient amount of light that passes through the second surface 422 and travels toward the photosensitive drum 70. In addition, AR which covers the translucent body 42
The light shielding body 44 may be formed on the surface of the coat layer 46.

Next, FIG. 5 is a conceptual diagram for explaining an optical path of emitted light from one light emitting element E. FIG. In the figure, elements such as the AR coating layer 46 and the refractive index matching liquid 54 are appropriately omitted.

As shown in FIG. 5, the component of the emitted light from the light emitting element E that has passed through the opening A1 is incident on each gradient index lens 34 of the converging lens array 30 while diffusing through the substrate 12. . Incident light to the converging lens array 30 travels in a meandering manner according to the refractive index distribution in the gradient index lens 34 and passes through the refractive index matching liquid 54 from the light exit surface 31 of the converging lens array 30. The light enters the translucent body 42. Of the incident light to the light transmitting member 42, the component that has passed through the opening A2 of the light shielding member 44 is transmitted through the AR coating layer 46 and reaches the image forming surface 72 of the photosensitive drum 70, and the other components are light shielding members. It is blocked at 44 and does not reach the photosensitive drum 70.

As shown in FIG. 5, the diameter d2 of the opening A2 is smaller than the luminous flux width of the light reaching the second surface 422 from the light emitting element E. Therefore, the spot region S1 where the light passing through the opening A2 reaches.
Is a configuration in which the light emitted from the converging lens array 30 directly reaches the surface of the photosensitive drum 70 (that is, a configuration in which the light flux restricting body 40 is not disposed, hereinafter referred to as “comparative”). The spot area S2 is smaller than the diameter DS2.

By the way, in the configuration in which m elements (m is a natural number) are interposed between the light exit surface 31 of the converging lens array 30 and the image forming surface 72 of the photosensitive drum 70, the converging lens array 30 in the air. If the thickness TA1 to TAm of each element and the refractive index NA1 to NAm of each element are selected so as to satisfy the following expression (1) in relation to the image plane distance (working distance) Lo, the image of the photosensitive drum 70 is obtained. The area of the spot region on the formation surface 72 can be logically minimized.
Lo = (TA1 / NA1) + (TA2 / NA2) + ... + (TAm / NAm) (1)
Now, as an element between the light exit surface 31 and the image forming surface 72, the translucent body 42 (thickness TA1,.
In consideration of the refractive index NA1) and the air layer (thickness TA2 and refractive index 1) from the second surface 422 to the image forming surface 72, in this embodiment, the expression (1) is transformed into the following expression (2). Is done.
Lo = (TA1 / NA1) + TA2 (2)
For example, when the thickness TA2 of the air layer is set to 0.1 mm under the configuration in which the converging lens array 30 having the image plane distance Lo of 2.4 mm and the translucent body 42 having the refractive index NA1 of 1.515 are adopted. Then, the optimum thickness TA1 of the translucent body 42 is about 3.5 mm (hereinafter referred to as “condition A”).

However, even if the expressions (1) and (2) are satisfied, the spot area may not be sufficiently miniaturized in an actual image forming apparatus. For example, a proportional configuration (light flux restricting body 40
The diameter d1 of the opening A1 (light emitting element E)
In the case where the area where the emitted light is emitted) is set to 50 μm, the diameter DS2 of the actual spot area S2
Is enlarged to about 85 μm. On the other hand, according to the configuration in which the light flux restricting body 40 is arranged as in the present embodiment, for example, by setting the diameter d2 of the opening A2 to 40 μm under the condition A,
It is possible to reduce the diameter DS1 of the spot area S1 to 48 μm. As described above, according to the present embodiment, the spot area S1 can be made finer and a high-definition image can be formed even when the low-cost focusing lens array 30 with insufficient imaging performance is employed. It becomes.

Even in a comparative configuration without the light flux restricting body 40, the light flux width of the emitted light from each light emitting element E is reduced by the light shielding layer 16 (opening A1). However, since the light passing through the opening A1 is diffused before reaching the image forming surface 72, it is difficult to sufficiently miniaturize the spot region S2 on the image forming surface 72. In the present embodiment, in addition to the configuration in which the light shielding layer 16 is formed in the light emitting device 10, the light flux width of the emitted light from each light emitting element E is reduced by the light shielding body 44 close to the photosensitive drum 70. Compared with a comparative configuration in which the light beam width is reduced only by the light shielding layer 16, the spot region S1 can be greatly miniaturized.

The above effect of miniaturizing the spot area S1 becomes more prominent as the light shield 44 is closer to the image forming surface 72. According to the present embodiment, since the light shielding body 44 is installed on the second surface 422 of the light transmitting body 42, the light shielding body 44 can easily approach the image forming surface 72 according to the thickness TA1 of the light transmitting body 42. (The interval TA2 between the second surface 422 of the translucent body 42 and the image forming surface 72 of the photosensitive drum 70 can be reduced). According to the test by the inventor of the present application, when the distance TA2 exceeds 0.3 mm, the amount of light shielded by the light shield 44 becomes excessive and the diameter DS1 of the spot region S1 increases remarkably. I came to get. Therefore, the distance TA2 between the second surface 422 and the image forming surface 72 is preferably 0.3 mm or less, and more preferably set to 0.1 mm or less. If the interval TA2 is selected so as to be within the above range, the spot region S1
Can substantially match the shape of the opening A2. Therefore, there is an advantage that the form of each spot region S1 is made uniform, and as a result, image unevenness is suppressed.

Further, the energy of the emitted light from the light emitting element E becomes maximum on a straight line extending in the Z direction from the center of the light emitting element E. Therefore, according to the present embodiment in which the light emitting element E and the opening A2 are overlapped so that the respective centers coincide with each other when viewed from the Z direction, the center of the light emitting element E and the center of the opening A2 do not coincide with each other when viewed from the Z direction. Compared to the configuration, the photosensitive drum 7 passes through the opening A2.
It is possible to sufficiently secure the energy of light reaching 0 (energy density in the image forming surface 72). In addition, the light transmitting element 42 is moved by the adjusting mechanism 50 while being in close contact with the converging lens array 30, so that the light emitting element E is maintained while maintaining the position of the light transmitting body 42 in the Z direction.
And the opening A2 can be adjusted with high accuracy so that the opening A2 overlaps.

<B: Second Embodiment>
Next, a second embodiment of the present invention will be described. In the present embodiment, elements having the same functions and functions as those of the first embodiment are denoted by the same reference numerals as those described above, and detailed description thereof is omitted as appropriate.

FIG. 6 is a cross-sectional view (a cross-sectional view corresponding to FIG. 2) showing a partial structure of the image forming apparatus according to the present embodiment. As shown in FIG. 6, a transparent body 36 is interposed in the gap between the light emitting device 10 and the converging lens array 30. The light transmitting body 36 is a light transmissive flat plate (for example, a glass substrate) having a refractive index equivalent to that of the substrate 12 of the light emitting device 10. The surface of the light transmitting body 36 facing the light emitting device 10 is in contact with the surface 121 of the substrate 12 (the surface opposite to the array surface of the light emitting elements E) 121. The surface of the translucent body 36 facing the converging lens array 30 is in contact with the light incident side end surface (hereinafter referred to as “light incident surface”) 32 of the converging lens array 30. The translucent body 36 is bonded to the substrate 12 and the converging lens array 30 by a light transmissive adhesive.

In the configuration in which an air layer is interposed in the gap between the light emitting device 10 and the converging lens array 30 as in the first embodiment, each light emitting element E on the surface 121 of the substrate 12 or the light incident surface 32 of the converging lens array 30. There is a possibility that light emitted from the light will be reflected. On the other hand, in the present embodiment, the gap between the light emitting device 10 and the converging lens array 30 is filled with the transparent body 36.
Reflection on the surface 121 and the light incident surface 32 is suppressed. As a result, the ratio of the amount of light incident on the converging lens array 30 out of the light emitted from each light emitting element E is increased as compared with the first embodiment. Therefore, a clear latent image can be formed on the image forming surface 72. In other words, since the electrical energy to be applied to the light emitting element E in order to reach the desired light amount on the image forming surface 72 is reduced, it is possible to suppress the deterioration of the light emitting element E over time.

In the configuration in which n elements (n is a natural number) are interposed between the light emitting element E (the light emitting layer 25) and the light incident surface 32 of the converging lens array 30, the converging lens array 30 in the air. Thickness TB1 to TBn of each element so as to satisfy the following formula (3) in relation to the working distance Li on the object side
And the refractive indexes NB1 to NBn of each element are selected.
Li = (TB1 / NB1) + (TB2 / NB2) + ... + (TBn / NBn) (3)
For example, the substrate 1 as an element between the light emitting element E and the light incident surface 32 of the converging lens array 30.
2 (thickness TB1 · refractive index NB1) and translucent body 36 (thickness TB2 · refractive index NB2)
(3) is transformed into the following equation (4).
Li = (TB1 / NB1) + (TB2 / NB2) (4)
The thickness TB2 and the refractive index NB2 of the transparent body 36 are set so as to satisfy the formula (4).

<C: Modification>
Various modifications can be made to each of the above embodiments. An example of a specific modification is as follows. In addition, you may combine each following aspect suitably.

(1) Modification 1
In each of the above embodiments, the configuration in which the light blocking body 44 is installed on the light transmitting body 42 is exemplified, but the light transmitting body 42 is not an essential requirement for the present invention. For example, as shown in FIG. 7, a configuration in which a light-shielding plate material in which a plurality of openings A2 are formed is disposed as a light-shielding body 442 in the gap between the focusing lens array 30 and the photosensitive drum 70 is also employed. According to the configuration of FIG. 7, the translucent body 42 is not necessary, and thus there is an advantage that the manufacturing cost of the exposure apparatus H is reduced.

However, in the configuration of FIG. 7, for example, deformation such as bending due to its own weight is likely to occur in the light shielding body 442, so that it is difficult to maintain the relative position of each opening A 2 and each light emitting element E. There's a problem. It is possible to solve the above problem by increasing the mechanical strength by forming the light shield 442 to a sufficient thickness as shown in FIG. 7, but in this case, the amount of light passing through the opening A2 is reduced. There is a problem of doing. That is, as shown in FIG. 8, the light shield 4 having a thickness t1.
4 is formed, the outgoing light from the range R1 on the light exit surface 31 of the converging lens array 30 passes through the opening A2, whereas the light shielding member is used to ensure mechanical strength as shown in FIG. 4
When the thickness t2 of 42 is increased (t2> t1), only the emitted light from the range R2 narrower than the range R1 can be taken into the opening A2.

According to the configuration in which the light shielding body 44 is formed on the surface of the light transmitting body 42 as in the first embodiment and the second embodiment, even if the light shielding body 44 is formed to be sufficiently thin, the light shielding body 44 is almost the same. Does not deform. Therefore, while maintaining each opening A2 and each light emitting element E at a desired position with high accuracy,
A sufficient amount of light incident on the opening A2 can be secured.

(2) Modification 2
In each of the above embodiments, the configuration in which the converging lens array 30 in which a plurality of gradient index lenses 34 are arranged has been exemplified, but a specific example of the light collecting body that collects the light emitted from each light emitting element E is shown. The general form is arbitrary. For example, instead of the converging lens array 30 in the above embodiments, a microlens array in which a plurality of microlenses (convex lenses or concave lenses) are arranged may be arranged.

(3) Modification 3
The shape of the opening A1 and the opening A2 is arbitrary. For example, an ellipse, an ellipse, or a polygon (for example, a square or a rectangle) may be used. Further, the configuration in which the opening A2 overlaps with the light emitting element E when viewed from the Z direction is not essential to the present invention. That is, an object to be exposed from the light emitting element E (image forming surface 72).
A configuration in which the opening A2 is present on the optical path to reach is sufficient.

(4) Modification 4
In each of the above embodiments, the configuration in which the light flux restricting body 40 (translucent body 42) is moved in order to adjust the relative position between the opening A1 and the light emitting element E is illustrated, but the light flux restricting body 40 is fixed. The light emitting device 10 (or the converging lens array 30 fixed to the light emitting device 10) may be moved by the adjusting mechanism 50 as it is. That is, in one aspect of the present invention, a configuration is adopted in which at least one of the light shield 44 and the light emitting device 10 is moved by the adjustment mechanism 50 so that the opening A1 and the light emitting element E have the intended positional relationship. Is done.

(5) Modification 5
In each of the above embodiments, the organic light emitting diode element is exemplified as the light emitting element E, but the specific form of the light emitting element E is arbitrarily changed. As for the light-emitting element applied to the present invention, it is possible to distinguish between an element that emits light and an element that changes the transmittance of external light (for example, a liquid crystal element), a current-driven element that is driven by current supply, and voltage application. There is no distinction from the voltage-driven element driven by. For example, inorganic EL elements, field emission (FE) elements, surface-conduction electron (SE) elements, ballistic electron surface emitting (BS) elements, and LED (Light Em
Various light emitting elements such as a fitting diode element and a liquid crystal element are used in the present invention.

<D: Application example>
Next, an image forming apparatus is exemplified as one form of equipment using the exposure apparatus according to the present invention.
FIG. 9 is a cross-sectional view showing a configuration of an image forming apparatus employing the exposure apparatus H according to each of the above embodiments. The image forming apparatus is a tandem type full-color image forming apparatus, and includes four exposure apparatuses H (HK, HC, HM, HY) according to the above-described form and four photosensitive drums corresponding to each exposure apparatus H. 70 (70K, 70C, 70M, 70Y). One exposure apparatus H is disposed so as to face the image forming surface (outer peripheral surface) of the corresponding photosensitive drum 70. Note that the subscripts “K”, “C”, “M”, and “Y” of each symbol are used for forming each visible image of black (K), cyan (C), magenta (M), and yellow (Y). Means.

As shown in FIG. 9, an endless intermediate transfer belt 72 is wound around the driving roller 711 and the driven roller 712. The four photosensitive drums 70 are arranged around the intermediate transfer belt 72 at a predetermined interval from each other. Each photosensitive drum 70 rotates in synchronization with driving of the intermediate transfer belt 72.

Around each photosensitive drum 70, in addition to the exposure apparatus H, a corona charger 731 (731K,
731C, 731M, 731Y) and developing unit 732 (732K, 732C, 732M, 732Y)
And are arranged. The corona charger 731 uniformly charges the image forming surface of the photosensitive drum 70 corresponding thereto. An electrostatic latent image is formed by exposing each charged image forming surface by each exposure device H. Each developing device 732 forms a visible image (visible image) on the photosensitive drum 70 by attaching a developer (toner) to the electrostatic latent image.

Each color (black, cyan, magenta, yellow) formed on the photosensitive drum 70 as described above.
Are sequentially transferred (primary transfer) to the surface of the intermediate transfer belt 72 to form a full-color visible image. Inside the intermediate transfer belt 72 are four primary transfer corotrons (transfer devices).
74 (74K, 74C, 74M, 74Y) are arranged. Each primary transfer corotron 74 electrostatically attracts a visible image from the corresponding photosensitive drum 70, thereby the photosensitive drum 7.
The visible image is transferred to the intermediate transfer belt 72 that passes through the gap between 0 and the primary transfer corotron 74.

The sheets (recording material) 75 are fed one by one from the paper feed cassette 762 by the pickup roller 761 and conveyed to the nip between the intermediate transfer belt 72 and the secondary transfer roller 77. The full-color visible image formed on the surface of the intermediate transfer belt 72 is transferred (secondary transfer) to one side of the sheet 75 by the secondary transfer roller 77 and is fixed to the sheet 75 by passing through the fixing roller pair 78. . The paper discharge roller pair 79 discharges the sheet 75 on which the visible image is fixed through the above steps.

Since the image forming apparatus exemplified above uses an organic light emitting diode element as a light source, the apparatus is made smaller than a configuration using a laser scanning optical system. Note that the present invention can also be applied to image forming apparatuses having configurations other than those exemplified above. For example, a rotary development type image forming apparatus, an image forming apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, or an image forming that forms a monochrome image The exposure apparatus of the present invention can also be used for the apparatus.

Further, the use of the exposure apparatus according to the present invention is not limited to the exposure of the image carrier. For example, the exposure apparatus of the present invention is employed in an image reading apparatus as a line-type illumination device that irradiates a reading target such as an original with light. As this type of image reading apparatus, there is a scanner, a copying machine or a reading part of a facsimile, a barcode reader, or a two-dimensional image code reader for reading a two-dimensional image code such as a QR code (registered trademark).

1 is a perspective view showing a partial structure of an image forming apparatus according to a first embodiment. It is sectional drawing seen from the II-II line | wire in FIG. It is a top view which shows the structure when the exposure apparatus H is seen from the photoreceptor drum side. It is sectional drawing seen from the IV-IV line in FIG. It is a conceptual diagram for demonstrating the optical path of the emitted light from a light emitting element. It is sectional drawing which shows the structure of the image forming apparatus which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the image forming apparatus which concerns on a modification. It is a conceptual diagram for demonstrating the relationship between the thickness of a light shielding body, and the light quantity which passes an opening part. 1 is a longitudinal sectional view showing an embodiment of an image forming apparatus according to the present invention.

Explanation of symbols

H: Exposure apparatus, E: Light emitting element, 10: Light emitting apparatus, 12: Substrate, 14: Wiring layer,
16: Light shielding layer, 21: First electrode, 23: Insulating layer, 25: Light emitting layer, 27: Second electrode, 30: Converging lens array, 31: Light exit surface, 34: Refraction Rate distribution lens, 40
... Light flux restricting body, 42 ... Translucent body, 421 ... First surface, 422 ... Second surface, 44,442
…… Shading body, 46 …… AR coating layer, A1, A2 …… Opening, 50 …… Adjustment mechanism, 54 ……
Refractive index matching liquid, 70... Photosensitive drum, 72... Image forming surface, S1... Spot area (diameter DS1), S2.

Claims (11)

A light emitting device in which a plurality of light emitting elements are arranged;
A light collector for condensing light emitted from each of the light emitting elements;
An exposure apparatus comprising: a first light blocking body formed with a plurality of openings through which light emitted from the light collecting body passes. 2. The exposure apparatus according to claim 1, wherein each opening of the first light shield overlaps each of the plurality of light emitting elements when viewed from the direction of the optical axis of the light collector. The exposure apparatus according to claim 1, wherein an area of each opening of the first light shield is smaller than an area of the light emitting element. In the light emitting device, a second opening in which a plurality of openings through which light emitted from the light emitting element passes is formed.
Including a shade,
The exposure apparatus according to any one of claims 1 to 3, wherein the condenser collects light transmitted through each opening of the second light shield. Comprising a first light-transmitting body disposed on the opposite side of the light-emitting device across the light collector;
The exposure apparatus according to claim 1, wherein the first light blocking body is fixed to a surface of the first light transmitting body opposite to the light collecting body. The exposure apparatus according to claim 7, wherein a surface of the first translucent body that faces the light collector is in close contact with the light collector. The exposure apparatus according to claim 6, wherein a refractive index matching liquid having a refractive index equivalent to that of the first light transmitting body is filled between the light collecting body and the first light transmitting body. The exposure apparatus according to any one of claims 5 to 7, wherein an antireflection treatment is performed on a surface of the first light transmitting body opposite to the light collecting body. Comprising a second light-transmitting body on which light emitted from each of the light-emitting elements is incident;
The light collector is disposed on the opposite side of the light emitting device with the second light transmissive member interposed therebetween, and
The exposure apparatus according to claim 1, wherein the light emitted from each of the light emitting elements that has passed through the light transmitting body is condensed. An image carrier on which a latent image is formed by exposure; and
The exposure apparatus according to any one of claims 1 to 9, wherein the image carrier is exposed by light beams that have passed through the openings of the first light shielding body.
An image forming apparatus comprising: a developing unit that forms a visible image by adding a developer to the latent image formed on the image carrier. The image forming apparatus according to claim 10, wherein a distance between a surface of the first light-shielding member facing the image carrier and an image forming surface of the image carrier is 0.3 mm or less.

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