JP2007152611A - Line head module and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line head module of which the light quantity transmission rate is improved by suppressing the manufacturing cost. <P>SOLUTION: This line head module 100 comprises a line head 510, a lens array 500 formed by collecting a plurality of cylindrical erecting equal magnification imaging lenses 102, and first and second transparent members 502, 504 which are respectively coupled to an incident face and a projection face of the lens array. In the first and second transparent members 502, 504, each of two faces opposing at least in the short side direction in the faces perpendicular to the incident and projection faces is finished to be a mirror surface and the thickness of each of the opposing faces in the short side direction is substantially equal to that of the lens array. As the light projected from the line head 510 and the light projected from the lens array 500 can be entirely reflected by the mirror-finished faces to be introduced in a prescribed range, it is possible to improve the light amount transmission rate without increasing the manufacturing cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a line head module and an image forming apparatus including the line head module.

  An image formed by a plurality of light sources arranged on a substrate is imaged on a photosensitive member such as a photosensitive drum via an erecting equal-magnification imaging lens, and the formed image is recorded on a recording medium such as paper. In order to reduce the size and weight of the optical head printer to be transferred, it is important to improve the light amount transmission rate, which is the ratio of the light that forms an image on the photoreceptor with respect to the light emitted from the light source. As a means for improving the light amount transmission rate, for example, in Patent Document 1, a line having a structure in which a light reflecting surface is arranged in the vicinity of an optical path between a light source and an erecting equal-magnification imaging lens and between a light source and a photoreceptor. A head module is presented.

JP 2000-309118 A

  However, the line head module having the above structure is difficult to adjust the relative position between the light reflecting surface and the erecting equal-magnification imaging lens, and the structure is complicated, leading to an increase in manufacturing cost and a decrease in productivity. There was a problem.

  In the following description, the optical distance indicates a length obtained by dividing the length of the transparent member in question in the optical axis direction by the refractive index of the transparent member.

  In the following description, “substantially equal” indicates that the error is within ± 10%. The reason for such a range is that if the error is within ± 10%, an image with sufficient accuracy for practical use can be obtained.

  In order to solve the above-described problems, a line head module according to the present invention includes a line head including a plurality of light sources, each of which is controlled independently, and a plurality of cylindrical erecting equal-magnification imaging lenses. A lens array formed by aligning an incident surface on which light is incident and an exit surface on which light incident from the incident surface is aligned, and connected to the incident surface, and the incident surface A first transparent member having at least two surfaces facing each other in the short direction, and having a thickness in the short direction substantially equal to the diameter of the erecting equal-magnification imaging lens; Further, at least two surfaces that are connected to the emission surface and are orthogonal to the emission surface are mirror-finished, and the thickness in the short direction is the erecting equal-magnification imaging lens. Substantially the diameter and so on There has a second transparent member.

  The first transparent member is located closer to the light source than the incident surface of the lens array. The thickness of the first transparent member in the direction orthogonal to the optical axis (hereinafter referred to as “thickness”) is the same as the diameter of the erecting equal-magnification imaging lens, that is, the thickness of the lens array. Therefore, light of a wider angle, that is, a larger amount of light is incident on the first transparent member than light incident on the incident surface of the lens array when the member is not present.

  As described above, the first transparent member is mirror-finished on the two surfaces facing each other in the short direction. Therefore, the two mirror-finished surfaces occupy target positions with respect to the central axis when the lens array is assumed to be a single lens, and the incident light is entirely between the two surfaces. Reflected and guided to the entrance surface of each erecting equal-magnification imaging lens forming the lens array. Since the erecting equal-magnification imaging lens forms the same image on the entrance surface and the exit surface, the same light as the incident light is emitted from the exit surface of the erecting equal-magnification imaging lens.

  Further, since the second transparent member is in contact with the exit surface of the lens array, the light emitted from the exit surface of the lens array is directly incident on the second transparent member. Like the first transparent member, the second transparent member has two mirrored surfaces facing each other in the short direction, and the incident surface is perpendicular to the optical axis, so that the incident light is between the two surfaces. Target position with respect to the central plane that is totally reflected and emitted from the surface opposite to the surface in contact with the lens array, and bisects the lens array of the light source in the direction perpendicular to the optical axis. To form an image.

  Therefore, with such a configuration, light that was originally not incident on the lens array out of light emitted from the light source is also incident on the lens array, and the center of each erecting equal-magnification imaging lens that constitutes the lens array. It is possible to form an image at a target position with respect to the light source with respect to the surface, and thereby it is possible to improve the light amount transmission rate while suppressing an increase in manufacturing cost and the like.

  The line head module of the present invention includes a line head composed of a plurality of light sources each controlled independently, and a plurality of cylindrical erecting equal-magnification imaging lenses, an incident surface on which light from the light sources is incident, A lens array formed by stacking two or more stages such that the incident surface and the exit surface are positioned on the same plane, in a state where the exit surface from which light incident from the entrance surface exits is aligned. In addition, two surfaces that are connected to the incident surface of the lens array and are orthogonal to the incident surface and facing each other in at least the lateral direction are mirror-finished, and the thickness in the lateral direction is equal to the thickness of the lens array. A first transparent member that matches the thickness in the stacking direction, and two surfaces that are connected to the exit surface of the lens array and face each other at least in the lateral direction among the surfaces orthogonal to the entrance surface. Are surface treated, said lateral direction thickness having a substantially equal second transparent member and the stacking direction of the thickness of the lens array.

  According to such a configuration, two or more stages of a group of erecting equal-magnification imaging lenses arranged on a plane are stacked to increase the thickness of the lens array so that light emitted from the light source can enter. The area can be increased. Therefore, it is possible to further improve the light amount transmission rate as compared with a line head module that uses only one stage of a group of erecting equal-magnification imaging lenses arranged on a plane in the lens array.

  Preferably, the optical distance of the first transparent member is substantially equal to the optical distance of the second transparent member.

  By making the optical distances of the first and second transparent members equal, the entrance surface of the first transparent member and the exit surface of the second transparent member are in the center plane of the erecting equal-magnification imaging lens. It lies on a plane that is symmetrical with respect to it. Therefore, the same image as the image formed on the incident surface of the first transparent member can be satisfactorily formed on the output surface of the second transparent member without adjusting the optical distance when the module is assembled. Thus, it is possible to improve the light amount transmission rate while suppressing an increase in manufacturing cost and the like.

  Preferably, the length of the first transparent member in the optical axis direction and the length of the second transparent member in the optical axis direction are substantially equal, and the first transparent member and the second transparent member Are made of the same material.

  According to such a structure, since the 1st transparent member and the 2nd transparent member can be made into the same member, procurement cost can be reduced.

  Preferably, the distance between the exit surface of the second transparent member and the photoconductor is substantially equal to the distance between the light source and the entrance surface of the first transparent member.

  As described above, since the first transparent member and the second transparent member have the same material and the same length in the optical axis direction, the light source and the photosensitive member have the same-magnification erect image. They are positioned on the target planes with respect to the center plane of the lens, and the image formed by the light source is accurately formed on the photosensitive member. Therefore, it is possible to improve the light amount transmission rate without degrading the accuracy of the image.

  Preferably, the light source is covered with a transparent substrate having a refractive index of ng and a thickness of Lg, and an incident surface of the first transparent member is in contact with the transparent substrate, and the second transparent member The relationship of L1 = Lg / ng is substantially established with respect to L1, which is the distance between the exit surface and the photoconductor. As described above, substantially established means that the error is within ± 10%.

  With this configuration, the optical distance between the light source and the incident surface of the first transparent member and the optical distance between the emission surface of the second transparent member and the photosensitive member are substantially the same. . As a result, the light source and the photoconductor are positioned on planes symmetrical to each other with respect to the center plane of the erecting equal-magnification imaging lens, and an image formed by the light source is accurately formed on the photoconductor. . Therefore, when the light source is formed on the transparent substrate, even if the incident surface of the first transparent member is brought into contact with the transparent substrate, deterioration of the image formed on the photosensitive member can be suppressed. A process of adjusting the gap between the incident surface of the transparent member and the transparent substrate is not required, and the light quantity transmission rate can be improved while suppressing an increase in manufacturing cost.

  Further, for various reasons, when the first distance that is the optical distance of the first transparent member must be longer than the second distance that is the optical distance of the second transparent member, Irradiation from the light source to the band-shaped region, which is two surfaces facing each other in the short direction, of the portion of the first transparent member that occupies the difference between the first distance and the second distance from the incident surface. It is preferable to form an antireflection layer for preventing the reflected light.

  With such a configuration, the light irradiated from the light source is not reflected in the band-like region by the antireflection layer, and the function as a light guide for transmitting the light irradiated from the light source is lost. Therefore, the length of the light guide path of the first transparent member is substantially equal to the length of the light guide path of the second transparent member, and an image formed by the light source is accurately formed on the photoconductor. Accordingly, even when the optical distance of the first transparent member is different from the optical distance of the second transparent member, the light amount transmission rate can be improved, so that the dimensions of each part in the line head module can be improved. The degree of freedom increases, and it becomes possible to improve the light amount transmission rate while suppressing an increase in manufacturing cost and the like.

  Preferably, the antireflection layer is a light shielding layer formed by application of a material that absorbs light.

  With such a configuration, since all the light incident on the antireflection layer portion is absorbed, an image formed by the light source can be accurately formed on the photoconductor. When this antireflection layer is not provided, the light reflected by the corresponding part of the first transparent member is imaged on another part on the photosensitive member because there is no corresponding part reflected by the second transparent member. It will end up.

  Preferably, the light source is formed on a transparent substrate, irradiates the lens array with light through the substrate, an incident surface of the first transparent member is in contact with the substrate, The sum of the optical distance and the difference distance is substantially equal to the optical distance between the exit surface of the second transparent member and the photoconductor.

  With such a configuration, the optical distance between the incident surface of the first transparent member and the light source and the exit surface of the second transparent member in a state where the incident surface of the first transparent member is abutted against the substrate. And the optical distance between the photosensitive member and the photosensitive member are substantially equal, and an image formed by the light source can be accurately formed on the photosensitive member. Therefore, even if the light source is formed on a transparent substrate, it is not necessary to adjust the gap between the incident surface of the first transparent member and the light source, and the light quantity transmission rate is improved while suppressing an increase in manufacturing cost and the like. Is possible.

  Preferably, the optical distance of the difference distance is substantially equal to the optical distance between the exit surface of the second transparent member and the photoconductor.

  With such a configuration, in a state where the incident surface of the first transparent member is abutted against the light source, the optical distance between the incident surface of the first transparent member and the light source, and the second transparent member The optical distance between the exit surface and the photoconductor is substantially equal, and an image formed by the light source can be accurately formed on the photoconductor. Therefore, even if the light source irradiates the lens array without passing through a transparent substrate such as glass, it is not necessary to adjust the gap between the incident surface of the first transparent member and the light source, which increases the manufacturing cost. It is possible to improve the light quantity transmission rate while suppressing it.

  In order to solve the above problems, an image forming apparatus according to the present invention includes the above-described line head module.

  As described above, the line head module according to the present invention improves the light amount transmission rate while suppressing an increase in manufacturing cost, etc., and thus the light amount transmission rate is high and the power consumption of the light source is reduced while suppressing an increase in manufacturing cost. A suppressed image forming apparatus can be provided.

  An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. In order to facilitate the description and understanding of each embodiment, the basic principle of the present invention will be described prior to the description of each embodiment.

  FIG. 1 shows a surface including an optical axis of a SELFOC lens (“SELFOC” is a registered trademark of Nippon Sheet Glass Co., Ltd., hereinafter referred to as SL) which is one of the elements constituting the line head module according to the present invention. FIG. SL is a glass fiber whose component has been adjusted so that the refractive index changes depending on the distance from the central axis (optical axis), and is cut to a predetermined length. It has the property of forming an erect real image.

  Light emitted from the light source 112 is incident on the incident surface 104 of the SL 102, travels in a curved shape inside the SL 102, as indicated by the first path 10, and exits the SL 102 at a symmetrical angle with the center plane 108 in between. The light exits from the surface 106 and forms an image at a point on the photosensitive member 114 that is plane-symmetric with respect to the light source 112 with the central surface 108 interposed therebetween. That is, light emitted from the point a1 of the light source 112 is at point a2 of the photoconductor 114, light emitted from the point b1 of the light source 112 is at point b2 of the photoconductor 114, and light emitted from the point c1 of the light source 112 is photoconductor. An erecting equal-magnification image is formed by being incident on the point c2 of 114 respectively. As described above, the passing point and angle of light passing through the incident surface 104 on the surface are symmetrical with respect to the passing point and angle of light passing through the exit surface 106 with respect to the center plane 108. .

  The length L of the SL 102 in the direction of the optical axis 101 is determined by the refractive index distribution described above. Further, the image plane distance, that is, the optical distance L11 between the incident surface 104 and the light source 112, and the optical distance L12 between the output surface 106 and the photosensitive member 114 are also determined as specific values. L11 and L12 are equal.

  The above-described erecting equal-magnification image is formed even when light emitted from a plurality of adjacent light sources is incident on the same SL or light emitted from one light source is incident on a plurality of adjacent SLs. There is no change. Therefore, when light is emitted to a plurality of SLs having the same length and arranged in a group, the images formed by the SLs overlap on the medium (photoreceptor), and one image as a whole. Form. That is, when an image is formed on a plane facing the image plane distance on one surface (incident surface), the image is formed on the photoconductor facing the other surface (output surface) with an image plane distance. An erect real image is formed. This is because a group of SLs having the same length and the same length (hereinafter referred to as “SLA (registered trademark of Nippon Sheet Glass Co., Ltd.)”) may be considered as one lens. is there.

  As described above, the light emitted from the point b1 on the light source 112 forms an image at the point b2 on the photoconductor 114. However, not all of the light emitted from the point b1 is imaged. The light imaged at the point b2 is within the incident angle A1 defined by the point b1 and the incident surface upper end 132 and the incident surface lower end 134 shown in FIG. The light.

  Light that has not entered the incident surface 104 does not form an image on the photosensitive member 114. Therefore, the light quantity transmission rate which is the ratio of the light imaged at the point b2 out of the light emitted from the point b1 (that is, the ratio of the light imaged on the photoconductor 114 out of the light emitted from the light source 112) is set. In order to improve, it is necessary to widen the incident angle A1. The same applies to the points a1 and c1.

  In order to increase the incident angle A1, it is necessary to shorten the distance between the incident surface 104 and the light source 112 or to increase the cross-sectional area at the central surface 108 of the SLA. However, the distance L11 between the incident surface 104 and the light source 112 is a unique image surface distance of the SLA and is difficult to change. Also, it is not preferable to increase the cross-sectional area of the SLA center plane 108 because it goes against the demand for module miniaturization and causes a cost increase. Therefore, in the line head module according to the present invention, the incident surface 104 and the light source 112 are connected to the entrance surface 104 and the exit surface 106 of the SL 102 by connecting a transparent member serving as a light guide for guiding light as a spacer, as will be described later. And the same effect as shortening the distance between the exit surface 106 and the photosensitive member 114 is produced.

  Note that the imaging distance between the light source, SL, and SL and the photosensitive member is a value unique to SL. For example, assuming that these values are Lo and Li, respectively, Lo = Li if the medium before and after SL is the same.

  Even when the refractive indexes of the two media are different, the above-described erecting equal-magnification image can be obtained if the distances in the optical axis direction of the two media are equal to the optical distance. In FIG. 2 to be described later, the transparent member is also connected to the emission surface 106 in order to equalize both the optical distances described above and equalize the light reflection environment before and after the SL. Otherwise, the light reflected by the mirror surface in the short direction of the first transparent member arranged on the SL incident side will reach the photoconductor without being reflected after passing through the SL, and this light will be imaged correctly. do not do.

  FIG. 2 is a schematic cross-sectional view of SL to which a transparent member having a light guide path function (hereinafter referred to as “light guide function”) is connected. A state is shown in which the first transparent member 202 is connected to the incident surface 104 of the SL 102 and the second transparent member 204 is connected to the outgoing surface 106 of the SL 102.

  A surface (hereinafter referred to as “incident surface”) 206 of the first transparent member 202 facing the light source 112 has a gap L <b> 3 with the light source 112. Similarly, the surface of the second transparent member 204 facing the photosensitive member 114 (hereinafter referred to as “exiting surface”) 208 has a gap L <b> 1 between the second transparent member 204 and the photosensitive member 114. Here, the lens shown in FIG. 2 is not an SLA in which a plurality of SL surfaces are aligned as described in FIG. 3 and subsequent drawings but a single SL. The shape of the second transparent member 204 is also a cylindrical shape having a diameter substantially equal to that of the SL 102.

  The side portions 103 of the first transparent member and the second transparent member are each mirror-polished, and light reaching the side portion 103 from the inside is totally reflected inside without leaking to the outside. Therefore, the light emitted from the point b1 and incident on the incident surface 206 of the first transparent member 202 passes through the inside of the first transparent member 202 as shown by the second path 20, and some light is on the optical axis. The light travels straight along, and is also reflected by the mirror surface of the first transparent member and travels to enter the incident surface 104. The light incident on the incident surface 104 is emitted at an angle similar to that when incident on the incident surface 104 due to the refractive index distribution shown in FIG. 1, and is incident on the second transparent member 204 from the output surface 106. The same applies to light emitted from other points (that is, point a1 and point c1) of the light source 112.

  The light incident on the second transparent member 204 travels straight along the optical axis, and the certain light is mirror-polished on the first transparent member 202 in the same manner as the light in the first transparent member 202 described above. After being totally reflected by the formed side surface portion 103 and traveling inside the second transparent member 204, the light is emitted from the emission surface 208 at the same angle as that incident on the first transparent member 202 and reaches the photosensitive member 114. . Here, the material and dimensions of the first transparent member 202 and the second transparent member 204 are the same, L1 = L3, and the optical distance and gap (L1, or L3) of each transparent member. ) Is equal to L0 (not shown), which is a unique image plane distance of SL102, the incident angle and the output angle coincide with each other, so that the image formed by the light source 112 is formed on the photoconductor 114.

  In this case, the incident surface 206 is closer to the light source 112 than the incident surface 104, and the cross-sectional shape perpendicular to the optical axis of the first transparent member 202 is the same as the cross-sectional shape perpendicular to the optical axis of the SL 102. The incident angle A2 with respect to the first transparent member 202 defined by the upper surface 232 and the lower surface 234 of the incident surface 206 shown in FIG. 2 is larger than the incident angle A1 with respect to the incident surface 104 of the SL 102 shown in FIG. Accordingly, the amount of light incident on the incident surface 104 is increased. That is, by attaching transparent members whose surfaces parallel to the optical axis are mirror-polished to both ends of the SL 102, the light quantity transmission rate can be improved while suppressing an increase in manufacturing cost without complicating the structure. it can.

  It should be noted that the first transparent member 202 and the second transparent member 204 are not affected even if the material and the length in the optical axis direction are different as long as the optical distance is the same. Can image.

  In addition, the function of totally reflecting incident light by a polished surface parallel to the optical axis and transmitting the light is hereinafter referred to as a light guide function, and a portion having the light guide function is referred to as a light guide portion.

  FIG. 3 is a perspective view showing one row of SLA 300 formed by arranging SLs in a single layer. As a reference, a cube figure showing the first to third planes (301 to 303) is also added.

  A plurality of SLs 102 having the same dimensions are arranged so that the optical axis 101 of each SL 102 is positioned on the first plane 301 and the incident surface 104 is positioned on the second plane 302. One row SLA300 capable of forming a double image is formed. A plane that is orthogonal to both the first plane 301 and the second plane 302 and includes the optical axis of any one of the plurality of SLs 102 is a third plane 303. The entrance surfaces 104 of the SLs gather to form the entrance surface 304 of the single row SLA, and the exit surfaces 106 of the SLs 102 gather to form the exit surface 306 of the single row SLA.

  As described above, since one lens is formed as a whole by the plurality of SLs 102, it is not necessary to connect individual transparent members to each SL 102, and the incident surface 304 of the single row SLA300 and the outgoing surface 306 of the single row SLA300. A transparent member having a rectangular cross section perpendicular to the optical axis and matching the shape may be connected to the entrance surface 304 and the exit surface 306 one by one. In this case, as will be described in each embodiment described later, mirror polishing is performed on two surfaces parallel to the first plane 301.

  FIG. 4 shows a line formed by arranging a plurality of SLs 102 having the same dimensions such that each optical axis 101 is located on the first plane and each incident surface is located on the second plane 302. FIG. 4 is a perspective view showing a two-row SLA 400 formed by stacking the SLA 300 (see FIG. 3) in a staggered manner with the surface positions aligned so that the incident surfaces 304 of each row are arranged on the same plane. It is possible to increase the area of the entrance surface and the exit surface while keeping the length in the direction perpendicular to the optical axis 101 (see FIG. 1) on the first plane 301 of the SLA constant according to the photoconductor. it can. By overlapping the same single-row SLA 300 in two rows, the areas of the entrance surface and the exit surface 306 are increased to form the entrance surface 404 of the double-row SLA and the exit surface 406 of the double-row SLA. Note that the method of stacking is not limited to a staggered pattern, and can be stacked in a grid pattern.

  FIG. 5 is a perspective view of the line head module 100 according to the present invention and the photoconductor 114 onto which an image is projected by the module. The line head module 100 is composed of one or more rows of SLA (hereinafter referred to as “one row”) formed by stacking one row of SLAs composed of a plurality of SLs 102 arranged in a plane, or one row of the SLA. SLA ”) 500, a first transparent member 502, and a second transparent member 504. In the SLA 500, a plurality of cylindrical SLs 102 in which the entrance surface and the exit surface are aligned are made into one array by a fixed frame or the like (not shown). Since the SLs 102 are densely arranged, the following description will be made assuming that the fixed frame does not affect the amount of light taken in.

  Similar to FIG. 3, a cube diagram showing the first to third planes (301 to 303) is also added. As described above, the light emitted from the light source 112 proceeds in the order of the first transparent member 502, the SLA 500, and the second transparent member 504, and forms an image on the photoconductor 114.

  The line head 510 is formed of a substrate and a plurality of light sources 112 regularly arranged on the substrate. The light source is preferably an inorganic LED, an organic LED, or the like, and each light source is controlled independently including the level of the light amount to form an image to be transmitted to the photoconductor 114. Note that the number of light sources 112 does not need to match the number of SLs 102 constituting the SLA 500, and can be determined according to the accuracy of the image to be transmitted. Further, the arrangement of the light sources is not limited to the configuration in which the square light sources 112 are arranged in a grid pattern. For example, circular light sources may be arranged in a staggered pattern. Note that a slight gap is required between the second transparent member 504 and the photosensitive member 114 for convenience of maintenance.

  Each embodiment will be described below.

(First embodiment)
FIG. 6 is a cross-sectional view of the line head module according to the first embodiment of the present invention in a third plane (see FIG. 5), including a photoreceptor on which an image is formed (written) by the line head module. Show.

  The first transparent member 502 is placed in contact with the incident surface 505 of the SLA, that is, the surface on which light from the light source is incident, and the exit surface 506 of the SLA 500, that is, the surface that emits light to the photoconductor 114 is disposed on the surface. The second transparent member 504 is disposed so as to contact. The surface of the first transparent member 502 that is abutted against the transparent substrate 602 is the incident surface 507 of the first transparent member 502, and the surface of the second transparent member 504 that faces the photoreceptor is the second surface. This is the emission surface 508 of the transparent member 502. In the cross section in the third plane, the SLA 500 and the transparent members 502 and 504 have the same dimensions except that the length in the direction of the optical axis 101 is different. There is a gap L <b> 1 between the second transparent member 504 and the photoreceptor 114. The first transparent member 502 is abutted against the transparent substrate 602 having a thickness of Lg on which the light source is formed, that is, the substrate of the light source, and there is no gap between the first transparent member 502 and the transparent substrate 602.

  The first transparent member 502 and the second transparent member 504 are formed of the same material and have substantially the same dimensions. Accordingly, the optical distances of both members are equal, and the same image is formed on the incident surface 507 of the first transparent member 502 and the exit surface 508 of the second transparent member 504.

  Both transparent members have a light guiding function as described above, because the two upper and lower surfaces parallel to the first plane 301 (see FIG. 5) are mirror-polished to form a polished surface 200. Therefore, part of the light incident on the incident surface 507 of the first transparent member 502 goes straight, and part of the light is reflected by the polishing surface 200 of the first transparent member 502 and enters the incident surface 505. Similarly, part of the light that has entered the second transparent member 504 from the exit surface 506 goes straight, and part of the light is reflected by the polishing surface 200 of the second transparent member 504, and is exposed from the exit surface 508. The light is emitted toward the body 114.

  L1 is determined by the convenience of maintenance. The value of Lg is determined so that the optical distance is equal to L1, that is, L1 = Lg / ng. As a result, the optical distances before and after the SLA 500 become equal, and the light source is sharply imaged on the image plane in accordance with the original image plane distance of the SLA.

  The light source 112 formed on the transparent substrate 602 is bottom emission type organic electroluminescence (hereinafter referred to as “organic EL”), and light is transmitted through the transparent substrate 602 toward the first transparent member 502. Is emitted. Unlike the first transparent member 502, the transparent substrate 602 does not have the polishing surface 200, so light emitted outside the line connecting the light source and the polishing surface 200 is incident on the first transparent member 502. do not do. That is, the transparent substrate 602 does not have a light guiding function, and only has a refractive index different from that of the gap L1, and has the same function as a translucent substance.

  Regarding the dimensions of each component, the thickness of the transparent substrate 602 is Lg, and the lengths of the first and second transparent members in the direction of the optical axis 101 (hereinafter referred to as “length”) are Lsg1 and Lsg2, respectively. It is. As described above, the gap between the second transparent member 504 and the photosensitive member 114 is L1. The refractive index of the transparent substrate 602 is ng, and the refractive indexes of the first transparent member 502 and the second transparent member 504 are nsg1 and nsg2, respectively. As described above, since the first transparent member 502 and the second transparent member 504 are formed of the same material and have the same dimensions, Lsg1 = Lsg2 and nsg1 = nsg2.

  The dimensions of both transparent members are such that the optical distance between the light source 112 and the entrance surface 505 and the optical distance between the exit surface 506 and the photoconductor 114 are specific to each SL constituting the SLA 500. It is determined to be equal to L0 (not shown) which is the image plane distance. That is, L0 = Lg / ng + Lsg1 / nsg1 = L1 + Lsg2 / nsg2. As described above, since Lsg1 = Lsg2 and Lg / ng = L1, the light source 112 and the photosensitive member 114 are positioned at the image formation point of the SLA 500, and the total reflection light guide path length is equal to the incident side and the outgoing side of the SLA. Equal on the side. The incident angle A6 is larger than the incident angle when it is assumed that neither of the transparent members is present. Therefore, the line head module of the present embodiment can image a larger amount of light on the photoconductor 114 than the normal line head module in a state where the SLA 500 is abutted against the transparent substrate 602 covering the light source 112. .

  As described above, if the first transparent member and the second transparent member are both equal in thickness to the SLA and have the same optical distance, the above effects can be obtained even if the materials and lengths are different. Will occur.

  In the practice of the present invention, it is necessary to ensure a gap L1 between the emission surface 508 of the second transparent member 504 and the photosensitive member 114 at a certain level or more. Therefore, the thickness of the transparent substrate 602 on which the organic EL as a light source is formed is calculated based on the gap, and then the gap and the thickness are calculated from the unique image plane distance of the SLA 500 constituting the line head module. By using a transparent member having a reduced length and having a surface parallel to the optical axis 101 mirror-polished as the light guide path, the light quantity transmission rate can be improved in a state where the first transparent member 502 is abutted. Therefore, the line head module according to the present embodiment does not require adjustment of the position between the light source and the SLA, and can improve the light amount transmission rate while suppressing an increase in manufacturing cost and the like.

(Second Embodiment)
FIG. 7 is a cross-sectional view of the line head module according to the second embodiment of the present invention on the third plane (see FIG. 5).

  Similar to the first embodiment, the first transparent member 502 is disposed on the incident surface 505 of the SLA 500, the second transparent member 504 is disposed on the exit surface 506, and the second transparent member 504 is photosensitive. There is a gap L1 between the bodies. The sum of the optical distance of the second transparent member 504 and L1 is an image plane distance unique to the SLA 500. Both the first and second transparent members have the same dimensions and materials, and the two surfaces parallel to the first plane 301 (see FIG. 5) are mirror surfaces as in the first embodiment. Polished.

  The difference from the first embodiment is the positional relationship between the light source 112 and the first transparent member 502. The light source 112 is an inorganic LED, and emits light from the surface opposite to the surface on which the light source 112 is formed. Therefore, there is no transparent substrate between the light source 112 and the first transparent member 502, and the gap L7. And L7 = L1.

  As described above, since the first transparent member 502 and the second transparent member 504 have the same size and material, the determination is made in this manner, so that the light source 112 and the incident surface 507 are separated and the light emitting surface 508 is Between the photosensitive members 114, the length of the light guide and the optical distance are equal. Further, the incident angle and the outgoing angle are also equal. Therefore, the line head module of this embodiment is symmetric with respect to the center plane 108, and the light emitted from the light source 112 forms an erecting equal-magnification image on the photosensitive member 114. Since the incident angle is increased by the transparent member having a light guiding function, the light amount transmission rate is improved.

  Unlike the first embodiment, since the first transparent member 502 cannot be abutted against the light source 112, adjustment during assembly is necessary, but the structure is complicated in the line head module using inorganic LEDs as the light source. It is possible to improve the light quantity transmission rate without making it. The light source 112 may be a top emission organic LED.

(Third embodiment)
FIG. 8 is a cross-sectional view of the line head module according to the third embodiment of the present invention on a third plane (see FIG. 5). A transparent member whose two surfaces parallel to the first plane (see FIG. 5) are mirror-polished is disposed on the incident surface 505 and the emission surface 506 of the SLA 500, and between the second transparent member 504 and the photoconductor 114. Is similar to the first and second embodiments in that there is a gap L1. The point that the light source 112 is an organic EL formed on the transparent substrate 602 and the point that the first transparent member 502 is abutted against the transparent substrate 602 are the same as in the first embodiment. As in FIG. 6, the light source 112 has a bottom emission type organic EL element formed on the transparent member 602, and emits light through the transparent substrate 602 toward the first transparent member 502.

  The first transparent member 502 and the second transparent member 504 are made of the same material, have a rectangular cross-sectional shape on the third plane (see FIG. 5), have the same thickness as the SLA 500, but have different lengths. One transparent member 502 is longer by L8. L8 is determined to be L8 / nsg1 + Lg / ng = L1 with respect to the thickness Lg of the transparent substrate 602, the refractive index ng of the transparent substrate 602, and the gap L1. Then, in the belt-like region 82 which is two surfaces parallel to the first plane (see FIG. 5) of the extension 80 which is a portion within L8 from the incident surface 507 in the first transparent member 502, the light absorbing paint Is applied.

  The belt-like region 82 absorbs light without reflecting it by the above-described light absorbing paint. Therefore, of the light that has entered the first transparent member 502 from the light source 112, the light that has hit the band-like region 82 is not totally reflected as described above, and is not guided to the incident surface 505 of the SLA 500. That is, since the extension portion 80 does not have a light guide function, the lengths of the light guide paths of the first transparent member 502 and the second transparent member 504 are equal. Similar to the first and second embodiments, the incident angle A8 on the light guide part surface 84 of the light guide part 86 is larger than the value when there is no transparent member, and the light quantity transmission rate is improved.

  As described above, the image forming apparatus needs to secure a certain gap or more between the line head module 100 and the photosensitive member 114. On the other hand, the thickness of the transparent substrate 602 on which the organic EL as a light source is formed may not be able to be increased in accordance with L1 due to restrictions on the manufacturing equipment of the organic EL. In such a case, the line head module according to the present embodiment provides the first transparent member 502 with the extension 80 that does not have a light guiding function so as to compensate for the thickness of the transparent substrate 602. The transparent member 502 can be abutted against the transparent substrate 602, and the light amount transmission rate can be improved in a state where the first transparent member 502 is abutted. Therefore, adjustment of the mutual position of the light source 112 and the SLA 500 is not required, and the light amount transmission rate can be improved while suppressing an increase in manufacturing cost and the like.

(Fourth embodiment)
FIG. 9 shows a cross-sectional view of the line head module according to the second embodiment of the present invention on a third plane (see FIG. 5). Similar to the first to third embodiments, the first transparent member 502 is disposed on the incident surface 505 of the SLA 500, the second transparent member 504 is disposed on the exit surface 506, and the second transparent member 504 There is a gap L1 between the photosensitive members 114.

  As in the third embodiment, the first transparent member 502 is the same as the second transparent member 504 in material, cross-sectional shape and thickness on the third plane (see FIG. 5), and the optical axis 101. The difference is that the length of the first transparent member 502 is slightly longer by L9.

  L9 is determined so that L9 / nsg1 = L1 with respect to the gap L1. A second portion which is two surfaces parallel to the first plane (see FIG. 5) of a portion 90 (hereinafter referred to as “second extension”) close to the first transparent member 502 having a length of L9. The band-shaped region 92 is coated with a light absorbing paint. Therefore, light incident on the second band-shaped region 92 out of light incident on the first transparent member 502 from the light source is absorbed without being reflected. Therefore, although the first transparent member 502 and the second transparent member 504 have different lengths in the direction of the optical axis 101, the lengths of the portions having the light guiding function are equal as in the third embodiment. Yes.

  The light source 112 is an inorganic LED as in the second embodiment, and emits light for forming an image toward the SLA 500 from the opposite side of the substrate on which the light source 112 is formed without passing through a transparent substrate. Yes. The first transparent member 502 is abutted against the light source 112. Further, as described above, L9 / nsg1 = L1, and the optical distance of the second extension 90 is equal to the gap L1.

  Therefore, L1 required for maintenance is determined, the length of the second transparent member 504 is determined so that the unique image plane distance L0 = L1 + Lsg2 / nsg2 of the SLA 500, and the length of the first transparent member 502 is set to L9. If it is determined that Lsg1 = Lsg2 + L9 with respect to L9 satisfying the relationship / nsg1 = L1, the first transparent member 502 is directly abutted against the light source 112, thereby simplifying the structure and reducing the manufacturing cost. The transmission rate can be improved.

  As described above, when the first and second transparent members serving as the light guides are disposed at both ends of the SLA 500 constituting the line head module, a predetermined gap is provided between the second transparent member 504 and the photosensitive member 114. It is necessary to secure a gap. An optical path having no light guide function corresponding to the gap is required between the first transparent member 502 and the light source 112.

  Therefore, as in the present embodiment, the first transparent member 502 is extended by an amount corresponding to the gap L1 between the photosensitive member 114 and the line head module, and a light shielding layer is formed on the extended portion, whereby the light source 112 is made of glass or the like. Even if the SLA 500 is irradiated with light without passing through the transparent substrate, it is not necessary to adjust the gap between the incident surface of the first transparent member 502 and the light source 112, and the amount of light can be transmitted while suppressing an increase in manufacturing cost. The rate can be improved.

(Fifth embodiment)
As described in the above first to fourth embodiments, the line head module according to the present invention is a photosensitive device in which an image formed by a plurality of light sources each controlled independently is separated by a predetermined gap L1. Form an image on the body. Therefore, the photosensitive member is moved relative to the line head module 100, the image formed by the light source 112 that changes with time is fixed on the photosensitive member, and the fixed image is transferred to a recording medium. Thus, an image can be formed on the recording medium.

  FIG. 10 is a schematic cross-sectional view of a tandem type full-color image forming apparatus using a belt intermediate transfer body system that includes the line head module 100 according to the present invention. In this image forming apparatus, four line head modules 100K, C, M, and Y each having the same configuration shown in any of the first to fourth embodiments have the same configuration. The photosensitive drums 160K, C, M, and Y as individual photosensitive members are disposed at the exposure positions. Here, the subscripts K, C, M, and Y indicate that they correspond to black, cyan, magenta, and yellow, respectively. The same applies to other components.

  As shown in the figure, this image forming apparatus is provided with a driving roller 171 and a driven roller 172, and an endless intermediate transfer belt 170 is wound around these rollers, and the driving roller 171 is indicated by an arrow. And the periphery of the driven roller 172.

  Around the intermediate transfer belt 170, four photosensitive drums 160K, C, M, and Y having a photosensitive layer on the outer peripheral surface are arranged at predetermined intervals. Each photosensitive drum rotates in synchronization with the driving of the intermediate transfer belt 170.

  Around each photosensitive drum 160K, C, M, Y, there is a corona charger 161K, C, M, Y, a line head module 100K, C, M, Y, and a developer 164K, C, M, Y, Is arranged. The corona chargers 161K, C, M, and Y can uniformly charge the outer peripheral surfaces of the corresponding photosensitive drums 160K, C, M, and Y. The line head modules 100K, C, M, and Y write an electrostatic latent image by emitting light from a light source on the charged outer peripheral surfaces of the photosensitive drums 160K, C, M, and Y, which are photosensitive members. As described in the first to fourth embodiments, the line head modules 100K, C, M, and Y have an improved light amount transmission rate, so that the power consumption is lower than when a conventional line head module is used. The same electrostatic latent image can be written.

  The developing devices 164K, C, M, and Y form a visible image, that is, a visible image on the photosensitive drums 160K, C, M, and Y by attaching toner as a developer to the electrostatic latent image.

  The black, cyan, magenta, and yellow developed images formed by the monochrome image forming stations corresponding to the four colors are sequentially primary-transferred onto the intermediate transfer belt 170, thereby the intermediate transfer belt 170. Overlaid on top, a full color image is obtained. Inside the intermediate transfer belt 170, primary transfer corotrons (transfer devices) 162K, C, M, and Y are arranged. The primary transfer corotrons 162K, C, M, and Y are arranged in the vicinity of the photosensitive drums 160K, C, M, and Y, respectively, and electrostatic images are electrostatically attracted from the photosensitive drums 160K, C, M, and Y. As a result, the visible image is transferred to the intermediate transfer belt 170 passing between the photosensitive drums 160K, C, M, and Y and the primary transfer corotron 162.

  Finally, the recording paper 152 as a recording medium on which an image is to be formed is unloaded one by one from the paper feeding cassette 151 by the pickup roller 153, and the intermediate transfer belt 170 in contact with the driving roller 171 and the secondary transfer belt 171. Sent to the nip between rollers 176. The full-color visible image on the intermediate transfer belt 170 is secondarily transferred to one side of the recording paper 152 by the secondary transfer roller 176 and passes through the fixing roller pair 177 serving as a fixing unit. It is fixed. Thereafter, the recording paper 152 is discharged by a paper discharge roller pair 178 onto a paper discharge cassette (not shown) provided on the image forming apparatus.

  As described above, by using the line head module with improved light amount transmission rate described in any one of the first to fourth embodiments as the electrostatic latent image writing unit, the same as the current image forming apparatus. Thus, it is possible to provide an image forming apparatus in which power consumption during use and manufacturing cost are suppressed.

  The image forming apparatus using the line head module according to the present invention is not limited to a tandem type full-color image forming apparatus, but is a rotary developing type full-color image forming apparatus using a belt intermediate transfer system, or a monochrome image forming apparatus. It can also be used in an image forming apparatus.

The schematic cross section of SL. The schematic cross section of SLA which connected the transparent member. The perspective view which shows SLA formed by arranging SL in the single layer. The perspective view which shows SLA formed by overlapping a group of SL arranged in the single layer. The perspective view which shows the outline of the line head module which concerns on this invention. Sectional drawing of the line head module which concerns on the 1st Embodiment of this invention. Sectional drawing of the line head module which concerns on the 2nd Embodiment of this invention. Sectional drawing of the line head module which concerns on the 3rd Embodiment of this invention. Sectional drawing of the line head module which concerns on the 4th Embodiment of this invention. 1 is a schematic cross-sectional view of an image forming apparatus including a line head module of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st path | route, 20 ... 2nd path | route, 80 ... Extension part, 82 ... Strip-shaped area | region, 84 ... Light guide part surface, 86 ... Light guide part, 90 ... 2nd extension part, 92 ... 2nd Belt-like region, 100 ... line head module, 101 ... optical axis of SL, 102 ... SL, 103 ... side face part, 104 ... incident face, 106 ... exit face, 108 ... central face, 112 ... light source, 114 ... photoconductor, 132 ... upper end of incident surface, 134 ... lower end of incident surface, 151 ... paper feed cassette, 152 ... recording paper as recording medium, pickup roller 153, 160 ... photosensitive drum as photosensitive member, 161 ... corona charger, 162 ... primary transfer Corotron, 164 ... developer, 170 ... intermediate transfer belt, 171 ... drive roller, 172 ... driven roller, 176 ... secondary transfer roller, 177 ... fixing roller pair, 178 ... discharge roller pair, 200 ... polishing , 202 ... the first transparent member, 204 ... the second transparent member, 206 ... the incident surface of the first transparent member, 208 ... the exit surface of the second transparent member, 232 ... the upper end of the incident surface, 234 ... the lower end of the incident surface , 300 ... one row SLA, 301 ... first plane, 302 ... second plane, 303 ... third plane, 304 ... incident surface of one row SLA, 306 ... exit surface of one row SLA, 400 ... two rows SLA, 404 ... 2 rows SLA entrance surface, 406 ... 2 rows SLA exit surface, 500 ... single row or multiple rows SLA, 502 ... first transparent member, 504 ... second transparent member, 505 ... SLA entrance surface 506... SLA exit surface, 507... First transparent member entrance surface, 508... Second transparent member exit surface, 510... Line head, 602.

Claims (11)

A line head consisting of a plurality of light sources each controlled independently;
A plurality of cylindrical erecting equal-magnification imaging lenses are formed by arranging an incident surface on which light from the light source is incident and an output surface on which light incident from the incident surface is aligned. A lens array,
Of the surfaces that are connected to the incident surface and are orthogonal to the incident surface, at least two surfaces facing in the short direction are mirror-finished, and the thickness in the short direction has a thickness of the erecting equal-magnification imaging lens. A first transparent member substantially equal to the diameter;
Of the surfaces that are connected to the exit surface and are orthogonal to the exit surface, at least two surfaces facing each other in the lateral direction are mirror-finished, and the thickness in the lateral direction is equal to that of the erecting equal-magnification imaging lens. And a second transparent member substantially equal in diameter to the line head module. A line head consisting of a plurality of light sources each controlled independently;
A plurality of cylindrical erecting equal-magnification imaging lenses in a state in which an incident surface on which light from the light source is incident and an output surface on which light incident from the incident surface is emitted are aligned. And a lens array formed by stacking two or more stages so that the emission surfaces are located on the same surface,
Two surfaces that are connected to the incident surface of the lens array and that are orthogonal to the incident surface are opposed to each other in at least the lateral direction, and the thickness in the lateral direction is equal to the thickness of the lens array. A first transparent member that matches the thickness in the stacking direction;
Two surfaces which are connected to the exit surface of the lens array and which are orthogonal to the entrance surface are opposed to each other in at least the lateral direction, and the thickness in the lateral direction is a stack of the lens arrays. And a second transparent member substantially equal to the thickness in the direction.   The first distance, which is a value obtained by dividing the length of the first transparent member in the optical axis direction by the refractive index, is substantially the second distance corresponding to the first distance of the second transparent member. The line head module according to claim 1, wherein the line head modules are equal to each other. The optical axis direction length of the first transparent member and the optical axis direction length of the second transparent member are substantially equal, and the first transparent member and the second transparent member are made of the same material. The line head module according to claim 3, wherein the line head module is formed by:   The distance between the exit surface from which light is emitted from the second transparent member and the photoconductor on which an image formed by the light source is formed is such that the light from the light source is incident on the light source and the first transparent member. The line head module according to claim 1, wherein the line head module is substantially equal to a distance between the incident surface and the incident surface.   The light source is covered with a transparent substrate having a refractive index of ng and a thickness of Lg, the incident surface of the first transparent member is in contact with the transparent substrate, and the emission of the second transparent member. 5. The relationship according to claim 1, wherein a relationship of L1 = Lg / ng is substantially established with respect to L1 which is a distance between a surface and the photosensitive member. The described line head module.   The first distance, which is a value obtained by dividing the length of the first transparent member in the optical axis direction by the refractive index, is greater than a second distance corresponding to the first distance of the second transparent member. The reflection of light emitted from the light source is prevented in a long band-shaped region of the first transparent member that occupies a distance of the difference between the first distance and the second distance from the incident surface. The line head module according to claim 1, wherein an antireflection layer is formed.   The line head module according to claim 7, wherein the antireflection layer is a light shielding layer formed by application of a light absorbing material. The light source is formed on a transparent substrate, irradiates the lens array with light through the substrate,
The incident surface of the first transparent member is in contact with the substrate,
The sum of the value obtained by dividing the thickness of the substrate by the refractive index and the value obtained by dividing the difference distance by the refractive index is substantially equal to the distance between the exit surface of the second transparent member and the photoconductor. The line head module according to claim 7, wherein the line head module is equal to:   The value obtained by dividing the distance of the difference by the refractive index is substantially equal to the distance between the exit surface of the second transparent member and the photoconductor. Line head module. An image forming apparatus comprising the line head module according to claim 1.

Images