JP2014089370A - Imaging element array, optical write apparatus, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging element array with reduced number of components.SOLUTION: In an imaging element array 1 formed by arranging a plurality of imaging elements 10, a light beam l is made incident from an object surface 16 to an incident lens surface 13, and is reflected toward a second reflection surface 22 by a first reflection surface 21 having positive refractive power in an arrangement direction X. Between a reflection surface front group and reflection surface rear group (between the first reflection surface 21 and the second reflection surface 22), an inverted image (intermediate image i) in the arrangement direction X is formed. The light beam l reflected by the second reflection surface 22 exits from the exit lens surface 15 to an image plane 17, to form an inverted image of the intermediate image i (inverted image of an object) in the arrangement direction X. The exit lens surface 15, the incident lens surface 13, the first reflection surface 21, and the second reflection surface 22 are formed on each predetermined surface of a transparent body 11. There is no need for two lens arrays facing each other, thereby reducing the number of components.

Description

  The present invention relates to an imaging element array, an optical writing apparatus, and an image forming apparatus, and more particularly to an imaging element array, an optical writing apparatus, and an image forming apparatus that can reduce the number of components.

  There are roughly two methods for performing digital optical writing in digital image output devices such as digital copying machines, printers, and digital facsimiles. One of them is an optical scanning method in which a light beam emitted from a light source such as a semiconductor laser is scanned by a polarizer, and an image is formed by an imaging lens to form a light spot. The other is a solid-state optical writing system in which a light beam is emitted from a light emitting element array such as an LED array or an EL array to form an optical spot by forming an image with an imaging element array.

  In the optical scanning method, since the light beam is scanned by the polarizer, the optical path length is increased. On the other hand, in the solid-state optical writing method in which the polarizer can be omitted, the optical path length can be reduced. Therefore, the solid-state optical writing method has an advantage that the optical writing device can be downsized as compared with the optical scanning method. Further, since the solid-state optical writing method does not use a movable part such as a polarizer, there is an advantage that noise can be suppressed as compared with the optical scanning method.

  As a conventional imaging element array used in the solid-state optical writing system, for example, one disclosed in Patent Document 1 is known. Patent Document 1 discloses a lens unit (imaging element array) in which two lens arrays (convex lenses) are opposed to each other with a light shielding plate interposed therebetween. The lens unit disclosed in Patent Document 1 can obtain an erect image by transmitting the light bundle from the light emitting element array to two lens arrays (convex lenses).

JP 2010-204208 A

  However, in the conventional technique, two lens arrays are required to assemble a lens unit (imaging element array), and a support for supporting the two lens arrays at a predetermined interval is required. There was a problem that the number of parts increased.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging element array, an optical writing device, and an image forming apparatus that can reduce the number of components.

Means for Solving the Problems and Effects of the Invention

  In order to achieve this object, according to the imaging element array according to claim 1, in which a plurality of imaging elements for converging light rays incident from the object plane on the image plane are arranged, the imaging element is: A light beam is incident on the incident lens surface from the object surface, and the light beam incident from the incident lens surface is reflected by the front surface of the reflecting surface composed of n-surface (n is a natural number) reflecting surfaces. The light beam reflected by the front reflecting surface group is incident on the rear reflecting surface group composed of the n reflecting surfaces and is reflected by the exit lens surface. The exit lens surface emits light incident from the rear surface group of the reflecting surfaces and forms an image on the image plane.

  By the incident lens surface and the front surface of the reflecting surface, an inverted image in the arrangement direction of the imaging elements of the object is formed as an intermediate image at a position between the front surface of the reflecting surface and the rear surface group of the reflecting surface. Further, an inverted image in the arrangement direction of the intermediate image is formed on the image plane with the intermediate image as the subject by the rear surface group of the reflecting surface and the exit lens surface. As a result, an erect image in the arrangement direction of the object is formed on the image plane in the entire lens system of the incident lens surface, the reflecting surface front group, the reflecting surface rear group, and the exit lens surface.

  The incident lens surface, the reflecting surface front group, the reflecting surface rear group, and the exit lens surface are formed on each predetermined surface of one transparent body. Therefore, it is not necessary to dispose the two lens arrays opposite to each other as in the prior art. Therefore, there is an effect that the number of parts can be reduced.

  According to the imaging element array according to claim 2, the refractive power in the array orthogonal direction of the imaging elements is set to be smaller than the refractive power in the array direction of the reflecting surface front group and the reflecting surface rear group, and the intermediate image is in the array orthogonal direction. Configured as a focal line extending to An inverted image in the direction orthogonal to the arrangement of the objects is formed on the image plane by the lens system including the incident lens surface, the front surface of the reflecting surface, the rear surface group of the reflecting surface, and the exit lens surface. As a result, in addition to the effect of the first aspect, there is an effect that the positional accuracy in the array orthogonal direction of the image formed on the image plane can be improved.

  According to the optical writing device of the third aspect, the light beam from the light emitting element array in which a plurality of light emitting elements are arranged at a predetermined interval is used for forming the light spot on the writing surface. And is focused on the writing surface. Thereby, there exists an effect similar to the effect which the imaging element array of Claim 1 or 2 show | plays.

  According to the image forming apparatus of claim 4, in the image forming body that performs exposure by irradiating a light spot to form an image, the light emitting element array includes a plurality of light emitting elements arranged at predetermined intervals. The light beam is incident on the imaging element array according to claim 1 and collected on the image carrier. Thereby, there exists an effect similar to the effect which the imaging element array of Claim 1 or 2 show | plays.

It is a perspective view of the image formation element array in 1st Embodiment. It is an optical path diagram of the image formation element array in the array orthogonal direction of the image formation elements. It is a schematic diagram which shows the relationship between a reflective surface group and reflected light. It is a schematic diagram of an optical writing device. 1 is a schematic diagram of an image forming apparatus. (A) is sectional drawing in the sequence orthogonal direction of the imaging element which comprises 1 unit of the imaging element array in 2nd Embodiment, (b) is a schematic diagram which shows the relationship between a reflective surface group and reflected light. It is. (A) is an optical path diagram of an imaging element constituting one unit of the imaging element array in the third embodiment, and (b) is a diagram illustrating one unit of the imaging element array in the fourth embodiment. It is an optical path figure of an image element.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIGS. First, the imaging element array 1 will be described with reference to FIG. FIG. 1 is a perspective view of an imaging element array 1 according to the first embodiment of the present invention. Note that arrows X, Y, and Z in FIG. 1 indicate axes orthogonal to each other, and arrow X indicates the arrangement direction of the imaging elements 10 in the imaging element array 1. An XY plane including the arrow Y and the arrow Z is a plane orthogonal to the arrow X (X axis), and indicates the array orthogonal direction of the imaging elements 10 in the imaging element array 1.

  As shown in FIG. 1, the imaging element array 1 is formed integrally with a plurality of imaging elements 10 made of synthetic resin. The imaging element 10 is formed by a transparent body 11 having a rectangular cross section. The transparent body 11 includes an incident end 12 that constitutes one end side, and an exit end 14 that constitutes the other end side opposite to the incident end 12. An entrance lens surface 13 and an exit lens surface 15 (see FIG. 2) are formed on the end surfaces of the entrance end 12 and the exit end 14, respectively. The transparent body 11 is made of a transparent synthetic resin having a refractive index larger than that of air.

  In the imaging element array 1, the incident lens surface 13 and the outgoing lens surface 15 are arranged along the arrangement direction X of the imaging elements 10 as optically equivalent lens surfaces. Further, in one unit of the imaging element 10, the optical axis of the incident lens surface 13 and the outgoing lens surface 15 is positioned along the direction orthogonal to the arrangement of the imaging elements 10 (arrow Z direction).

  Next, imaging with the imaging element array 1 will be described with reference to FIGS. Since the plurality of imaging elements 10 constituting the imaging element array 1 are configured as optically equivalent, imaging by one unit of the imaging element 10 will be described below. FIG. 2 is an optical path diagram of the imaging element array 1 in the direction orthogonal to the arrangement of the imaging elements 10, and FIG. 3 shows a reflecting surface group 20 (first reflecting surface 21 and second reflecting surface 22) and reflected light (light ray l). It is a schematic diagram which shows the relationship.

  As shown in FIG. 2, in each unit of the imaging element 10, a light beam l emitted from an arbitrary light source on the object surface 16 enters the transparent body 11 from the incident lens surface 13, and the reflecting surface group 20 (first surface). The light is reflected by the first reflecting surface 21 and the second reflecting surface 22), is emitted from the exit lens surface 15, and forms an image on the image surface 17.

  The entrance lens surface 13 and the exit lens surface 15 are portions where the light beam l enters and exits, and the entrance lens surface 13 and the exit lens surface 15 are set so that their optical axes (in the arrow Z direction) are parallel to each other. ing. Thereby, the object plane 16 and the image plane 17 can be arranged at positions facing each other with the imaging element array 1 interposed therebetween.

  The entrance lens surface 13 and the exit lens surface 15 both have a positive refractive power, and the refractive power is set to the same value. In addition, the incident lens surface 13 and the exit lens surface 15 are both lens surfaces in which the refractive power in the arrangement direction X of the imaging elements 10 and the refractive power in the arrangement orthogonal direction (the paper surface direction in FIG. 2) are different. However, the present invention is not limited to this, and the entrance lens surface 13 and the exit lens surface 15 can be formed using a spherical lens or the like.

  The reflecting surface group 20 is a group composed of positive and even reflecting surfaces, and is for reflecting the light beam l incident from the incident lens surface 13 toward the outgoing lens surface 15. The reflecting surface group 20 includes a reflecting surface front group composed of n reflecting surfaces (where n is a natural number) and a reflecting surface rear group composed of n reflecting surfaces that reflect light incident from the reflecting surface front group. It consists of. In the present embodiment, the reflecting surface group 20 includes two reflecting surfaces (a reflecting surface front group and a reflecting surface rear group), which are a first reflecting surface 21 (a reflecting surface front group) and a second reflecting surface 22 (a reflecting surface rear group). 1 side).

  The first reflecting surface 21 (the reflecting surface front group) and the second reflecting surface 22 (the reflecting surface rear group) are set to the same refractive power. Further, the incident lens surface 13 and the reflecting surface front group (first reflecting surface 21) are configured as a lens system having a positive refractive power. Each reflecting surface is a curved surface (anamorphic aspherical surface) in which the refractive power in the arrangement direction X of the imaging elements 10 and the refractive power in the arrangement orthogonal direction (paper surface direction in FIG. 2) are different. Specifically, the refractive power in the arrangement direction X of the imaging elements 10 is set to a value larger than the refractive power in the arrangement orthogonal direction. The imaging element 10 is positioned at a position between the first reflecting surface 21 (the reflecting surface front group) and the second reflecting surface 22 (the reflecting surface rear group) by the incident lens surface 13 and the reflecting surface front group (first reflecting surface 21). This is because an intermediate image (inverted image) in the arrangement direction X is formed.

  Further, the first reflecting surface 21 has incident light incident on the second reflecting surface 22 in the direction orthogonal to the arrangement of the imaging elements 10 in relation to the incident angle of the light beam incident on the first reflecting surface 21 from the incident lens surface 13. The angle is set so as to be totally reflected. In addition, the second reflecting surface 22 totally reflects the incident light toward the exit lens surface 15 in the direction orthogonal to the arrangement of the imaging elements 10 in relation to the incident angle of the light beam incident from the first reflecting surface 21. The angle is set. Thereby, it can prevent that the light quantity of the reflected light from the 1st reflective surface 21 or the 2nd reflective surface 22 reduces.

  In addition, a reflective coating (metal coating) is applied to the surface of the transparent body 11 corresponding to the back surfaces of the first reflective surface 21 and the second reflective surface 22 to improve the reflectivity of the first reflective surface 21 and the second reflective surface 22. It is possible.

  As shown in FIG. 3, the first reflecting surface 21 has a positive refractive power in the arrangement direction X of the imaging elements 10 and forms an intermediate image i in the arrangement direction X, while the entire system of the reflecting surface group 20. As described above, an erecting equal-magnification image in the arrangement direction is formed without forming an intermediate image in the arrangement orthogonal direction. As a result, due to the refractive power of the incident lens surface 13 and the first reflecting surface 21 (the reflecting surface front group) in the arranging direction X, the array is orthogonal between the first reflecting surface 21 and the second reflecting surface 22 (the reflecting surface rear group). An intermediate image i (focal line) extending in the direction (the arrow Z direction in FIG. 3) is formed. The intermediate image i (focal line) forms an inverted image in the arrangement direction X of the imaging elements 10, and the light beam l enters the second reflecting surface 22 using the image as a subject.

  Returning to FIG. As shown in FIG. 2, the light beam l incident on the second reflecting surface 22 from the first reflecting surface 21 is reflected toward the exit lens surface 15 and is imaged on the image surface 17 by the exit lens surface 15. The incident lens surface 12, the first reflecting surface 21, the second reflecting surface 22, and the exit lens surface 15 are formed on each surface of the transparent body 11, and the transparent body 11 is more positive by the entrance lens surface 13 and the exit lens surface 15. Therefore, an inverted image of an object in the direction orthogonal to the arrangement of the imaging elements 10 is formed on the image plane 17.

  On the other hand, the intermediate image i (see FIG. 3) formed between the first reflecting surface 21 and the second reflecting surface 22 is inverted imaging in the arrangement direction X of the imaging elements 10. Using the intermediate image i as a subject, an inverted image in the arrangement direction X of the intermediate image i is formed on the image surface 17 by the second reflecting surface 22 and the exit lens surface 15. Therefore, in the entire lens system of the transparent body 11, an erect image (erect life-size image) of the object in the arrangement direction X of the imaging elements 10 can be obtained on the image plane 17. Accordingly, one unit of the imaging elements 10 constituting the imaging element array 1 has a substantially erecting equal magnification system in the arrangement direction X in the relationship between the object plane 16 and the image plane 17, and in the arrangement orthogonal direction. It can be said that it is a nearly inverted unity system. Therefore, the imaging element array 1 can be configured as an optical system that forms an erect image of an object in a line shape on the image plane 17.

  The imaging element 10 forms an intermediate image i (focal line) extending in the direction orthogonal to the array (direction of arrow Z in FIG. 3) by the reflecting surface group 20, and therefore the image (light spot) formed on the image plane 17 The positional accuracy in the array orthogonal direction (the Y direction in FIG. 2) can be improved.

  That is, when the refractive power of the lens surface and the reflecting surface is set so as to form an intermediate image (focal point) as the entire optical system, the incident angle (in the arrangement direction X in the array direction X) of the light incident from the incident lens surface 13 is set. ), Intermediate images (focal points) are formed at a plurality of locations in the arrangement direction (the arrow X direction in FIG. 3). When the intermediate image is an inverted image formation in the array direction and the array orthogonal direction of the imaging elements 10, the intermediate image (focal point) may be displaced in the array orthogonal direction (the Y direction in FIG. 3). When an intermediate image (focal point) displaced in the array orthogonal direction (arrow Y direction in FIG. 3) is used as the subject, the position of the image (light spot) connected to the image plane 17 is the array orthogonal direction (arrow Y direction in FIG. 2). ), The position accuracy of the light spot may be lowered.

  On the other hand, the image forming element 10 does not form an intermediate image in the array orthogonal direction as the entire optical system, but transmits an intermediate image i (focal line connecting inverted image formation in the array direction) extending in the array orthogonal direction to the transparent body 11. Form inside. Even when the incident angles (in the arrangement direction X) of the light rays incident from the incident lens surface 13 are different, an image is formed on the intermediate image i (focal line). By using the intermediate image i as a subject, a light spot (an inverted image in the direction orthogonal to the array and an erect image in the array direction) is formed on the image plane 17. Compared to the case where a plurality of focal points (inverted imaging in the arrangement direction and the orthogonal direction in the arrangement direction) are used as the subject, the focal spot (intermediate image i) is formed as the subject, so that the position accuracy of the light spot in the arrangement orthogonal direction Can be improved. Therefore, according to the imaging element array 1, it is possible to suppress image deviation and blurring in the direction orthogonal to the arrangement of the imaging elements 10.

  Further, according to the imaging element array 1, the incident lens surface 13, the first reflecting surface 21, the second reflecting surface 22, and the exit lens surface 15 that can form an erect image in the arrangement direction X of the imaging elements 10 on the image plane are: Since it is formed on each surface of one transparent body 11, there is no need to dispose two lens arrays opposite to each other as in the prior art. Therefore, the number of parts of the imaging element array 1 can be reduced.

  In the optical system (imaging element 10) having a positive refractive power made up of the incident lens surface 13 and the outgoing lens surface 15, the transparent body 11 is increased by increasing the refractive index of the transparent body 11 and the curvature of the incident lens surface 13. It is possible to set so that the intermediate image i is formed between the entrance lens surface 13 and the exit lens surface 15 without forming the reflection surface group 20 on the surface 11. However, since a great restriction is imposed on the material of the transparent body 11 and the curvature of the incident lens surface 13, there is a problem that the degree of freedom in designing the imaging element 10 is lowered.

  On the other hand, according to the imaging element array 1 in the present embodiment, the imaging element 10 includes an incident lens surface 13 and an exit lens in an optical system having a positive refractive power composed of an entrance lens surface 13 and an exit lens surface 15. By forming the reflecting surface group 20 (the reflecting surface front group and the reflecting surface rear group) with the lens surface 15, the first reflecting surface 21 (the reflecting surface front group) and the second reflecting surface 22 (the reflecting surface rear group) The intermediate image i is set so as to be formed between the two. Therefore, in the arrangement direction X, the refractive powers of the two surfaces of the incident lens surface 13 and the first reflecting surface 21 can be set so that an intermediate image i (inverted image formation) is formed. Further, the refractive powers of the two surfaces of the second reflecting surface 22 and the exit lens surface 15 can be set so that the intermediate image i can be formed on the image surface 17 as a subject. Therefore, the degree of freedom in designing the imaging element 10 can be increased.

  Next, with reference to FIG. 4, an optical writing device 30 configured using the imaging element array 1 will be described. FIG. 4 is a schematic diagram of the optical writing device 30, and illustrates a cross section of the optical writing device 30 in the direction orthogonal to the arrangement of the imaging elements 10. The optical writing device 30 condenses the light flux emitted from each light emitting element 35 of the light emitting element array 33 on the writing surface 36 (image forming surface) via the image forming element array 1, and the light emitting element array. It is an apparatus for irradiating each light spot (imaging light) to a position corresponding to the arrangement of 33.

  The support 31 is a member for supporting the imaging element array 1 and the light emitting element array 33, and is disposed along the longitudinal direction of the imaging element array 1 (the arrangement direction of the imaging elements 10). The imaging element array 1 is mounted in the formed mounting portion 32. The imaging element array 1 is supported by the incident lens surface 13 and the outgoing lens surface 15 formed so that the optical axes are parallel, and the incident lens surface 13 and the outgoing lens surface 15 face opposite to each other. Assembly to the body 31 can be facilitated. Further, since the light emitting element array 33 can be mounted on one of the opposing surfaces of the support 31 (two surfaces in the left-right direction in FIG. 4) and light can be emitted from the other surface, the optical writing device 30 can be used as an image forming apparatus. It is possible to improve the degree of freedom when arranging in the same manner.

  The light emitting element array 33 is formed by mounting an LED array chip in which a plurality of LEDs (light emitting diodes) as the light emitting elements 35 are arranged on a substrate 34. In general, several tens to several hundreds of LEDs are arranged in one LED array chip, and a driver IC (not shown) and several tens of LED array chips are mounted on the substrate 34. A large number of light emitting elements 35 are arranged along the longitudinal direction of the imaging element array 1 (the arrangement direction of the imaging elements 10). One dot of the light emitting element 35 corresponds to one dot of the image, and each dot can be sequentially turned on according to the output image under the control of the driver IC on the substrate 34.

  The light emitting element 35 is arranged at a position coinciding with the object plane 16 (see FIG. 2). The light emitted from the light emitting element 35 is converged by the imaging element array 1 on the writing surface 36, for example, the surface of the image carrier made of a photoconductor to form a light spot.

  Next, an image forming apparatus 40 configured using the optical writing apparatus 30 will be described with reference to FIG. Here, an image forming apparatus 40 using an electrophotographic technique will be described as an example of an image forming technique. FIG. 5 is a schematic diagram of the image forming apparatus 40.

  As shown in FIG. 5, the image forming apparatus 40 includes an image carrier 41 composed of a photosensitive drum, a charging unit 42, an optical writing device 30, a developing unit 43, and a transfer unit arranged around the image carrier 41. 44, a cleaning unit 46, and a charge removal unit 47 are mainly provided. A fixing unit 45 for fixing the toner image transferred onto the medium m such as recording paper is disposed on the side of the transfer unit 44.

  The image forming apparatus 40 applies a uniform potential (charging) to the image carrier 41 that is driven to rotate (the rotation direction is clockwise in FIG. 5) by the charging unit 42. Next, an electrostatic latent image is formed on the image carrier 41 by irradiating the image carrier 41 with a light spot emitted from the optical writing device 30 (exposure). A toner is attached to the electrostatic latent image by the developing unit 43 to form a toner image on the image carrier 41 (development). Next, the toner image is transferred (transferred) onto the medium m by the transfer unit 44, and pressure or heat is applied to the medium m by the fixing unit 45 (fixing). In the image carrier 41 having the toner image transferred onto the medium m, the toner remaining on the surface is removed by the cleaning unit 46, and the charge is removed by the charge eliminating unit 47. Thereby, a series of image forming processes by the electrophotographic technique is completed.

  In the present embodiment, an example of the image forming apparatus 40 having one image carrier 41 has been described. However, the present invention is not necessarily limited to this. For example, the image carrier 41 and the surrounding charging unit 42, etc. The present invention can be applied to a so-called tandem type color image forming apparatus in which various image forming units (excluding the fixing unit 45) are arranged in parallel in the conveyance direction of the medium m. In this color image forming apparatus, the side-by-side image carriers 41 and the like are used as image forming units for respective colors such as cyan (C), magenta (M), yellow (Y), and black (Bk). Then, images of each color such as C, M, Y, Bk, etc. are formed, and sequentially superimposed and transferred onto the medium m. Finally, a color image can be obtained by fixing the superimposed images of the respective colors to the medium m by the fixing unit 45.

  Next, a second embodiment will be described with reference to FIG. In the first embodiment, the case where a focal line (intermediate image i, inverted imaging in the arrangement direction) extending in the direction orthogonal to the arrangement of the imaging elements 10 is formed by the reflecting surface group 20 has been described. In contrast, in the second embodiment, a case will be described in which a focal point (an intermediate image i, an inverted image in the arrangement direction and the arrangement orthogonal direction) is formed by the reflecting surface group 54. In addition, about the part same as the part demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted.

  FIG. 6A is a cross-sectional view of the imaging elements 50 constituting one unit of the imaging element array in the second embodiment in the array orthogonal direction X, and FIG. 6B constitutes the reflecting surface group 54. It is a schematic diagram which shows the relationship between the 1st reflective surface 54a and the 2nd reflective surface 54b, and reflected light (light ray 1). A plurality of imaging elements 50 shown in FIG. 6A are provided in series along the arrangement direction X (FIG. 6A, the direction perpendicular to the paper surface) as an optically equivalent element. In FIG. 6A, the hatching applied to the cut surface of the cross section of the imaging element 50 is omitted for the sake of simplicity.

  As shown in FIG. 6A, the imaging element 50 includes an incident lens surface 53 and a reflection surface group 54 (first surface) formed on an incident end 52 of a transparent synthetic resin transparent body 51 having light transmittance. The reflecting surface 54 a, the second reflecting surface 54 b), and the exit lens surface 56 formed on the exit end 55. A light beam emitted from an arbitrary light source on an object surface (not shown) enters the transparent body 51 from the incident lens surface 53, is reflected by the first reflection surface 54a (the front surface of the reflection surface), and the reflected light is first. 2 Reflected by the reflecting surface 54b (the reflecting surface rear group), exits from the exit lens surface 56, and forms an image on an image surface (not shown). The transparent body 51 is configured as a lens system having positive refractive power by the entrance lens surface 53 and the exit lens surface 56.

  The incident lens surface 53 and the output lens surface 56 are aspherical surfaces (rotationally symmetric surfaces or nonrotationally symmetric surfaces), and the first reflecting surface 54 a and the second reflecting surface 54 b have a refractive power in the arrangement direction X of the imaging elements 50. It is a concave surface (anamorphic aspherical surface such as a toroidal surface or a free-form surface) having a different refractive power in the direction orthogonal to the arrangement. The first reflecting surface 54a and the second reflecting surface 54b have positive refractive powers in the arrangement direction X and the arrangement orthogonal direction.

  As shown in FIG. 6B, the intermediate image i (focal point) is formed between the first reflecting surface 54a and the second reflecting surface 54b by the refractive power in the arrangement direction X and the arrangement orthogonal direction of the first reflecting surface 54a. It is formed. Therefore, the reflected light (light beam 1) from the first reflecting surface 54a forms an inverted image of the object, and the image is incident on the second reflecting surface 54b as a subject.

  Further, since the transparent body 11 is configured as a lens system (convex lens) having a positive refractive power by the incident lens surface 53 and the output lens surface 56, an inverted image of an object is formed on the image surface (not shown). Is done. Accordingly, one unit of the imaging element 50 constituting the imaging element array has a substantially erecting equal magnification system in the arrangement direction X and the arrangement orthogonal direction in the relationship between the object plane and the image plane (both not shown). Can be made. Therefore, the imaging element array can be configured as an optical system that can form an erect image of an object on the image plane.

  Next, a third embodiment and a fourth embodiment will be described with reference to FIG. In the first embodiment and the second embodiment, the case where each of the reflecting surface groups 20 and 54 is configured by two reflecting surfaces (the reflecting surface front group and the reflecting surface rear group are each one surface) has been described. On the other hand, in the third embodiment, a case will be described in which a reflecting surface group 64 (a reflecting surface front group and a reflecting surface rear group are each two surfaces) is configured by four reflecting surfaces. In the fourth embodiment, six reflecting surfaces are formed. The case where the reflecting surface group 74 (the reflecting surface front group and the reflecting surface rear group are each three surfaces) is configured by the reflecting surface will be described. In addition, about the part same as 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted.

  FIG. 7A is an optical path diagram of the imaging element 60 constituting one unit of the imaging element array in the third embodiment, and FIG. 7B is one of the imaging element array in the fourth embodiment. It is an optical path figure of image formation element 70 which constitutes a unit. The imaging elements 60 and 70 shown in FIGS. 7A and 7B are optically equivalent in the arrangement direction X (FIG. 7A and FIG. 7B in the direction perpendicular to the paper surface). A plurality of image forming element arrays are formed by being provided in series.

  As shown in FIG. 7A, the imaging element 60 includes an incident lens surface 63 formed on an incident end 62 of a transparent synthetic resin transparent body 61 having optical transparency, and a reflecting surface group 64 (first surface). 1 reflecting surface 64a to 4th reflecting surface 64d) and an exit lens surface 66 formed on the exit end portion 65. A light beam l emitted from an arbitrary light source on an object surface (not shown) enters the transparent body 61 from the incident lens surface 63, and is reflected by the reflecting surface group 64 (first reflecting surface 64a to fourth reflecting surface 64d). The reflected light is reflected from the exit lens surface 66 and forms an image on an image surface (not shown). The transparent body 61 is configured as a lens system having a positive refractive power by the entrance lens surface 63 and the exit lens surface 66. Further, the front surface of the reflecting surface (the first reflecting surface 64a and the second reflecting surface 64b) and the rear surface of the reflecting surface (the third reflecting surface 64c and the fourth reflecting surface 64d) are set to the same refractive power.

  According to the imaging element 60, the positive direction of the arrangement direction (arrow X direction) by the incident lens surface 63 and the two reflecting surfaces (the first reflecting surface 64a and the second reflecting surface 64b) near the incident lens surface 63 is positive. Due to the refractive power, an intermediate image i (focal line) extending in the array orthogonal direction (arrow Y direction) is formed between the second reflecting surface 64b and the third reflecting surface 64c, which are in the middle of the reflecting surface group 64. The intermediate image i (focal line) becomes an inverted image of an object in the arrangement direction (arrow X direction), and the image is emitted from the exit lens surface 66 as a subject, and is arranged on the image plane (not shown) in the arrangement direction (arrow). An equal-magnification image of an object that is upright in the (X direction) and inverted in the array orthogonal direction (arrow Y direction) is formed.

  According to the third embodiment, the reflecting surface group 64 is configured by four reflecting surfaces (first reflecting surface 64a to fourth reflecting surface 64d), and the incident lens surface 63 and the reflecting surface front group (the first reflecting surface 64a and the first reflecting surface 64a and the fourth reflecting surface 64d). The intermediate image i can be formed by the positive refractive power in the arrangement direction (arrow X direction) of the second reflecting surface 64b). Using the intermediate image as a subject, an erect image of the object is formed by the positive refractive power in the arrangement direction (arrow X direction) of the rear surface of the reflecting surface (the third reflecting surface 64c and the fourth reflecting surface 64d) and the exit lens surface 66. Imaged. The refractive power necessary to form the intermediate image i can be borne by the three surfaces of the incident lens surface 63 and the front surface of the reflecting surface (the first reflecting surface 64a and the second reflecting surface 64b). In addition, the refractive power necessary to form an erect image of the object on the image plane can be borne by the three surfaces of the reflecting surface rear group (the third reflecting surface 64c and the fourth reflecting surface 64d) and the exit lens surface 66. Compared with the first embodiment, the degree of freedom in designing the lens surface and the reflecting surface can be improved.

  Next, as shown in FIG. 7B, the imaging element 70 includes an incident lens surface 73 formed on an incident end 72 of a transparent synthetic resin transparent body 71 having light transmittance, and a reflecting surface group. 74 (first reflecting surface 74a to sixth reflecting surface 74f) and an exit lens surface 76 formed on the exit end 75. A light beam emitted from an arbitrary light source on an object surface (not shown) enters the transparent body 71 from the incident lens surface 73 and is reflected by the reflecting surface group 74 (the first reflecting surface 74a to the sixth reflecting surface 74f). Then, the reflected light exits from the exit lens surface 76 and forms an image on an image plane (not shown).

  According to the imaging element 70, the positive refraction in the arrangement direction (arrow X direction) of the incident lens surface 73 and the three reflecting surfaces (the first reflecting surface 74a to the third reflecting surface 74c) near the incident lens surface 73. Due to the force, an intermediate image i (focal line) extending in the array orthogonal direction (arrow Z direction) is formed between the third reflecting surface 74c and the fourth reflecting surface 74d, which are in the middle of the reflecting surface group 74. The intermediate image i (focal line) becomes an inverted image of an object in the arrangement direction (arrow X direction), and the image is emitted from the exit lens surface 76 as a subject, and is arranged on the image plane (not shown) in the arrangement direction (arrow). An equal-magnification image of an object that is upright in the (X direction) and inverted in the array orthogonal direction (arrow Y direction) is formed.

  According to the fourth embodiment, the reflecting surface group 74 is configured by six reflecting surfaces (first reflecting surface 74a to sixth reflecting surface 74f), and the incident lens surface 73 and the reflecting surface front group (first reflecting surfaces 74a to 74f). The intermediate image i is formed by the positive refractive power in the arrangement direction (arrow X direction) of the four surfaces of the third reflecting surface 74c). Further, an image is formed on the image plane by the positive refractive power in the arrangement direction (arrow X direction) of the four reflecting surface rear group (fourth reflecting surface 74d to sixth reflecting surface 74f) and the exit lens surface 76. The refractive power necessary to form the intermediate image i can be borne by the four surfaces of the incident lens surface 73 and the first reflecting surface 74a to the third reflecting surface 74c, and the refractive power necessary for image formation on the image surface is reflected by the fourth reflection. Since the four surfaces of the surface 74d to the sixth reflection surface 74f and the exit lens surface 76 can be burdened, the degree of freedom in designing the lens surface and the reflection surface can be further improved as compared with the third embodiment.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed. For example, the shapes of the transparent bodies 11, 51, 61, 71 described in the above embodiments, the number of the imaging elements 10, 50, 60, 70 arranged in the imaging element array 1 are examples, and are arbitrary. Can be set to

  In each of the above embodiments, the case where the transparent bodies 11, 51, 61, 71 are made of synthetic resin has been described. However, the present invention is not necessarily limited to this, and the transparent bodies 11, 51, 61, 71 are made of glass. Of course it is possible.

  In each of the above-described embodiments, the imaging elements 10 and 50 having the reflecting surface groups 20 and 54 (each one reflecting surface front group and the reflecting surface rear group) each including two reflecting surfaces are configured from four reflecting surfaces. An imaging element 60 having a reflecting surface group 64 (two reflecting surface front groups and reflecting surface rear group), and a reflecting surface group 74 composed of six reflecting surfaces (each reflecting surface front group and reflecting surface group). The imaging element array in which a plurality of imaging elements 70 having the rear group) are arranged has been described. However, the number of reflecting surfaces constituting the reflecting surface group is not limited to 2, 4, and 6. The number of reflecting surfaces constituting the reflecting surface group can be appropriately set as long as it is a positive even number. An incident lens surface 13, 53, 63, 73 and an n-plane (where n is a natural number) reflecting surface (having positive refractive power in the arrangement direction (arrow X direction)) within the optical path of the reflecting surface group (in front of the reflecting surface) Inverted imaging (intermediate image i) in the direction of arrangement of the imaging elements (in the direction of the arrow X) is formed at a position between the group and the rear surface of the reflecting surface), and the intermediate image i is used as a subject, This is because an image can be formed on the image plane by the exit lens surfaces 15, 56, 66 and 76.

  In each of the above-described embodiments, the case where the light emitting element array 33 that irradiates the image forming element array 1 with the light flux is configured by the LED array. However, the present invention is not necessarily limited thereto, and other light emitting element arrays may be used. Of course it is possible to adopt. Examples of the other light emitting element array include an EL light emitting element array and an optical shutter array in which a shutter array such as a liquid crystal shutter is disposed in front of a light source such as a single halogen lamp. In the optical shutter array, a shutter array that can be controlled to be opened and closed for each pixel is arranged in front of the light source. Opening and closing the shutter array for each pixel can be equivalent to an array in which a plurality of light emitting elements (light emitting points) are arranged in a pseudo manner.

  Although not described in the above embodiments, the object surface 16 and the imaging elements 10, 50, 60, and 70 (incident lens surfaces 13, 53, 63, and 73) and the image surface 17 and the imaging element 10 are omitted. , 50, 60, and 70 (outgoing lens surfaces 15, 56, 66, and 76), it is possible to arrange an aperture that blocks a part of the light beam that does not contribute to the formation of the intermediate image i. By arranging the aperture, it is possible to suppress the light rays incident on the imaging elements 10, 50, 60, 70 from being transmitted to the adjacent imaging elements 10, 50, 60, 70. Thereby, it can suppress that the contrast of the image formation of an object falls by the transmission of the light ray between the adjacent image formation elements 10, 50, 60, 70. The resolution of the optical system can be improved by suppressing the decrease in the contrast of the imaging.

  Although not described in each of the above-described embodiments, a slit extending in the direction orthogonal to the groove-like arrangement is formed between adjacent imaging elements 10, 50, 60, 70 of the imaging element array 1, and the imaging elements 10, It is possible to separate 50, 60, and 70 (a state in which a part of the imaging elements 10, 50, 60, and 70 is connected). By forming a slit between the imaging elements 10, 50, 60, and 70, the light incident from the incident lens surfaces 13, 53, 63, and 73 is emitted from the adjacent imaging elements 10, 50, 60, and 70. The optical path toward the surfaces 15, 56, 66, 76 can be blocked. Accordingly, it is possible to prevent light incident on the imaging elements 10, 50, 60, 70 from entering the adjacent imaging elements 10, 50, 60, 70. , 70 can suppress ghost light that is condensed at a position where it should not be imaged.

  Further, it is possible to insert or apply a light shielding member into a slit formed between adjacent imaging elements 10, 50, 60, and 70 extending in the direction orthogonal to the array. The light shielding member is formed of a member having a refractive index comparable to that of the imaging elements 10, 50, 60, and 70 (transparent bodies 11, 51, 61, and 71). By inserting or applying the light shielding member into the slit, it is possible to suppress the reflection of the light beam at the boundary surface of the slit. Furthermore, the light beam transmitted through the boundary surface of the slit can be attenuated by forming the light shielding member with a material having absorption characteristics with respect to the wavelength of the light source. As a result, it is possible to suppress the generation of ghost light caused by the light beam reflected at the boundary surface of the slit.

DESCRIPTION OF SYMBOLS 1 Imaging element array 10, 50, 60, 70 Imaging element 11, 51, 61, 71 Transparent body 13, 53, 63, 73 Incident lens surface 15, 56, 66, 76 Outgoing lens surface 16 Object surface 17 Image surface 21, 54a First reflective surface (reflective surface, front group of reflective surfaces)
22, 54b Second reflecting surface (reflecting surface, rear group of reflecting surfaces)
DESCRIPTION OF SYMBOLS 30 Optical writing apparatus 33 Light emitting element array 35 Light emitting element 36 Writing surface 40 Image forming apparatus 41 Image carrier 64a, 74a 1st reflective surface (reflective surface, a part of reflective surface front group)
64b, 74b Second reflecting surface (reflecting surface, part of front group of reflecting surfaces)
64c Third reflecting surface (reflecting surface, part of rear group of reflecting surfaces)
64d Fourth reflecting surface (reflecting surface, part of rear group of reflecting surfaces)
74c Third reflecting surface (reflecting surface, part of front group of reflecting surfaces)
74d Fourth reflecting surface (reflecting surface, part of rear group of reflecting surfaces)
74e Fifth reflecting surface (reflecting surface, part of rear group of reflecting surfaces)
74f Sixth reflecting surface (reflecting surface, part of rear group of reflecting surfaces)
i Intermediate image l Ray

Claims (4)

In an imaging element array in which a plurality of imaging elements that collect light rays incident from the object plane are arranged on the image plane,
The imaging element is
An incident lens surface on which light rays are incident from the object surface;
A reflecting surface front group composed of n-surface (where n is a natural number) reflecting surfaces that reflect light incident from the incident lens surface;
A reflecting surface rear group composed of n reflecting surfaces that reflect light incident from the reflecting surface front group;
An exit lens surface that emits a light beam incident from the rear surface of the reflecting surface and forms an image on the image surface, and
The exit lens surface, the incident lens surface, the reflecting surface front group and the reflecting surface rear group are formed on each predetermined surface of one transparent body,
The incident lens surface and the reflecting surface front group form an inverted image of an object in the arrangement direction of the imaging elements as an intermediate image at a position between the reflecting surface front group and the reflecting surface rear group,
The imaging element array, wherein the reflecting surface rear group and the exit lens surface form an inverted image of the intermediate image in the arrangement direction on the image plane with the intermediate image as a subject. The reflecting surface front group and the reflecting surface rear group are set such that the refractive power in the array orthogonal direction of the imaging elements is smaller than the refractive power in the array direction,
The intermediate image is configured as a focal line extending in the array orthogonal direction,
The lens system including the incident lens surface, the reflecting surface front group, the reflecting surface rear group, and the exit lens surface forms an inverted image of the object in the array orthogonal direction on the image surface. The imaging element array according to claim 1. In an optical writing apparatus for forming an optical spot on a writing surface,
A light emitting element array in which a plurality of light emitting elements are arranged at predetermined intervals;
An optical writing apparatus comprising: the imaging element array according to claim 1, wherein light from the light emitting element array is condensed on the writing surface. In an image forming apparatus for irradiating an image carrier with a light spot to perform exposure and forming an image,
A light emitting element array in which a plurality of light emitting elements are arranged at predetermined intervals;
An image forming apparatus comprising: the imaging element array according to claim 1, which condenses light rays from the light emitting element array onto the image carrier.

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