JP2006119481A - Image reading unit, image forming apparatus equipped with the image reading unit, and method for assembling the image reading unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading unit which can adjust a lens rotationally around its optical axis without allowing the occurrence of dislocation on the arrangement posture of a light shielding member with respect to a photoelectric conversion element, an image forming apparatus equipped with the image reading unit, and a method for assembling the image reading unit. <P>SOLUTION: First and second lens barrels 27 and 28 which respectively hold two lenses 26 for causing the reduction imaging of the reflected image from a manuscript in the line type photoelectric conversion element 24 are placed on a base member 21 and the first lens barrel 17 is provided with the light shielding member 32 for correcting the fourth power rule of cosine of the lens 26. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading unit used in a copying machine, a facsimile machine, a scanner device, and the like, an image forming apparatus including the image reading unit, and an assembling method of the image reading unit.

  2. Description of the Related Art Conventionally, there has been known an image reading unit that is provided in a copying machine, a facsimile machine, a scanner device, and the like and reads an image from a document (for example, see Patent Document 1).

  The image reading unit has a reduction optical system. This reduction optical system reduces and forms a reflection image from a document on a line-type photoelectric conversion element through a plurality of lenses arranged in series with each other. The reduced and focused reflection image is converted into an electric signal by the photoelectric conversion element. Each lens and the photoelectric conversion element are each provided on a plate-like base member.

  The amount of light that passes through the lens and enters the photoelectric conversion element decreases according to the cosine fourth law as the incident position of the light on the photoelectric conversion element moves away from the optical axis. In order to correct the decrease in the amount of light around the optical axis according to the cosine fourth law of this lens, a light shielding member for performing shading correction on the optical axis of the lens is provided on the base member independently of each lens. Yes. The light shielding member is adjusted so as to have an appropriate posture with respect to each lens and each photoelectric conversion element.

  That is, at the time of assembling the image reading unit, the photoelectric conversion element is disposed on the base member, and the light shielding member is disposed on the base member so as to have an appropriate posture with respect to the photoelectric conversion element. Further, each lens is arranged between the photoelectric conversion element and the light shielding member on the base member so as to coincide with a preset virtual optical axis, and on the plane including the Z axis and the base member along the optical axis. By moving each lens along the X-axis that intersects the Z-axis at right angles and the Y-axis along the thickness direction of the base member, each lens is rotated around the X-axis and Y-axis. Thus, adjustment is performed so that the optical axis of each lens coincides with the virtual optical axis. After the adjustment of each lens, in order to correct the aberration of imaging on the photoelectric conversion element due to the variation in imaging performance with respect to the rotation direction around the optical axis of each lens, each lens is moved around the Z axis, that is, around the optical axis. Rotate.

  However, since each lens and the light shielding member are independently arranged on the base member, the relative position of each lens and the light shielding member may be shifted during adjustment of each lens with respect to the photoelectric conversion element. For this reason, an appropriate shading effect by the light shielding member may not be obtained. Accordingly, in order to correct the relative position shift between each lens and the light shielding member, it is necessary to readjust the arrangement posture of the light shielding member again, and it takes time to assemble the image reading unit.

Therefore, a configuration has been proposed in which each lens is accommodated in a lens barrel, a light shielding member is provided at the end of the lens barrel, and the lens mirror or the like is disposed on the base member. According to this, since each lens and the light-shielding member are integrally provided in the lens barrel, adjustment is made such that each lens is moved along the X, Y, and Z axes when the respective lenses are aligned. Alternatively, even when adjustment is performed to rotate around the X axis and the Y axis, it is possible to prevent the relative position between each lens and the light shielding member from being shifted.
JP 2002-101263 A (page 4-6, FIG. 1)

  However, since the proper posture of the lens for blocking photoelectric conversion and the posture of the light shielding member for blocking photoelectric conversion do not always coincide, when each lens and the light blocking member are integrally provided in the lens barrel, photoelectric conversion is performed. If each lens is rotated around the optical axis in order to correct the aberration of image formation on the element, the light shielding member rotates around the optical axis together with each lens. For this reason, the attitude | position of the light shielding member with respect to a photoelectric conversion element will shift | deviate from an appropriate attitude | position. Conversely, when the light shielding member is rotated around the optical axis to adjust the position of the light shielding member with respect to the photoelectric conversion element, each lens rotates around the optical axis integrally with the light shielding member. There is a problem that the posture of the user deviates from the proper posture.

  An object of the present invention is to form an image on a photoelectric conversion element while maintaining the posture of the light shielding member with respect to the photoelectric conversion element in an appropriate posture even when the light shielding member is provided integrally with the lens in the lens barrel. An image reading unit that can rotate and adjust a lens around an optical axis in order to correct the aberration of the image, an image forming apparatus including the image reading unit, and an assembling method of the image reading unit.

  In order to solve the above problems, the invention described in claim 1 is characterized in that at least two lenses for reducing and forming a reflected image from a document on a line-type photoelectric conversion element, and a lens barrel for holding each of the lenses. Each of the lens barrels and a base member on which the line-type photoelectric conversion element is disposed, and one of the lens barrels is provided with a light shielding member for correcting the cosine fourth law of the lens. It is characterized by being.

  The invention according to claim 2 is the invention according to claim 1, wherein the one lens barrel is made of resin, and the light shielding member is integrally formed with the one lens barrel. The image reading unit according to claim 1.

  According to a third aspect of the present invention, in the first aspect of the present invention, the light shielding member is fixed to the one lens barrel after adjusting the rotational posture around the optical axis of the one lens barrel. It is characterized by being.

  According to a fourth aspect of the present invention, there is provided a scanner device comprising the image reading unit according to any one of the first to third aspects.

  A fifth aspect of the present invention is the scanner apparatus according to the fourth aspect of the present invention, characterized in that a part of the housing is constituted by the base member.

  A sixth aspect of the present invention is an image forming apparatus including the image reading unit according to any one of the first to fifth aspects.

  According to a seventh aspect of the present invention, there is provided at least two lenses for reducing and forming a reflected image from a document on a line-type photoelectric conversion element, a lens barrel for holding the lenses, the lens barrels, and the lenses. And a base member on which a line type photoelectric conversion element is disposed, and an assembling method of an image reading unit, wherein a light shielding member for correcting the cosine fourth law of the lens is fixed to one lens barrel. After determining the position of the one lens barrel, the other lens barrel is rotated around the optical axis to correct the aberration of image formation on the line-type photoelectric conversion element, and then the other The lens barrel is fixed to the base member.

   According to an eighth aspect of the present invention, there is provided at least two lenses for reducing a reflected image from a document on a line-type photoelectric conversion element, a lens barrel for holding the lenses, the lens barrels, And a light shielding member having a window hole for correcting the cosine fourth law of the lens in one lens barrel. The light shielding member is rotatable around the optical axis of the lens. To the line-type photoelectric conversion element after adjusting the rotation posture of the light-shielding member provided on the one lens barrel with respect to the line-type photoelectric conversion element. In order to correct the aberration of image formation, the one lens barrel provided with at least the light shielding member of the two lens barrels is connected to the line type photoelectric conversion element of the light shielding member. The lens barrel is fixed to the base member, and then the light shielding member is fixed to the one lens barrel. To do.

  According to the configuration of claim 1 and the method of claim 7, each lens is held by a separate lens barrel, and the light shielding member is integrally formed with one lens barrel. When the image reading unit is assembled, one of the light shielding members is integrally formed when correcting the imaging aberration on the line type photoelectric conversion element due to the variation in the imaging performance with respect to the rotation direction around the optical axis of each lens. The other lens barrel can be rotated around the optical axis without rotating the lens barrel around the optical axis. As a result, the other lens barrel can be rotated around the optical axis while maintaining the proper posture of the light shielding member with respect to the line type photoelectric conversion element. The aberration of image formation on the line-type photoelectric conversion element can be reliably corrected without degrading the shading effect due to deviation from the posture.

  According to the configuration of the second aspect, since the light shielding member is integrally formed with one lens barrel, the number of parts of the image reading unit can be reduced, and the number of assembly steps of the image reading unit can be reduced. Reduction can be achieved.

  According to the configuration of claim 1 and claim 3 and the method of claim 8, each lens is held by a separate lens barrel, and the light shielding member is rotatable around its optical axis. Since it is held in one lens barrel, when the image reading unit is assembled, the aberration of imaging on the line type photoelectric conversion element due to the variation in imaging performance with respect to the rotation direction around the optical axis of each lens is corrected. Sometimes, each lens barrel can be rotated around the optical axis without rotating the light shielding member provided on one lens barrel around the optical axis. Accordingly, each lens barrel can be rotated and adjusted around the optical axis while maintaining an appropriate rotation posture of the light shielding member with respect to the line type photoelectric conversion element. Therefore, it is possible to reliably reduce the aberration of image formation on the line-type photoelectric conversion element without degrading the shading effect due to the deviation from the proper rotation posture.

  Therefore, since each lens barrel can be rotated and adjusted around the optical axis, finer adjustments can be made than when one lens barrel is rotated around the optical axis. The aberration of image formation on the element can be further reduced.

  According to the configuration of the fourth aspect, by using the image reading unit according to the present invention for the scanner device, it is possible to provide a scanner device capable of high-quality image reading.

  According to the configuration of the fifth aspect, by constituting a part of the housing of the scanner device with the base member, it is possible to reduce the number of assembling steps of the scanner device and to perform high-quality image reading. A scanner device can be provided.

  According to the configuration of the sixth aspect, by using the image reading unit in the image forming apparatus, it is possible to provide an image forming apparatus capable of high-quality image reading.

  Hereinafter, the present invention will be described with reference to the illustrated embodiments.

<Example 1>
FIG. 1 shows an example in which an image reading unit 10 according to the present invention is applied to a scanner device 11.

  The scanner device 11 according to the present invention closes a housing 14 having a rectangular bottom wall 12 and four side walls 13 rising from each edge of the bottom wall, and an upper end opening defined by each side wall 13 of the housing. And a contact glass 15 on which a document (not shown) to be read is placed.

  In the housing 14, a first traveling body 16 and a second traveling body 17 that extend along the X axis that crosses the Z axis along the longitudinal direction of the housing are arranged at intervals from each other in the Z axis direction. ing. Both the first and second traveling bodies 16 and 17 are movable in the same direction along the Z axis. Further, the image reading unit 10 described above is provided on the bottom wall 12 in the housing 14.

  The first traveling body 16 includes a light source (not shown) that extends along the extending direction of the first traveling body and illuminates the original in a line along the X axis, and the original illuminated by the light source. A first mirror 18 that reflects the reflected image to be reflected toward the second traveling body 17 is provided.

  The second traveling body 17 includes a second mirror 19 that reflects the reflected image from the first mirror 18 downward in the vertical direction, and a line that will be described later of the image reading unit 10 by reflecting the reflected image from the second mirror. A third mirror 20 that reflects toward the photoelectric conversion element 24 is provided. As is well known in the art, the second traveling body 17 has the speed of the first traveling body 16 so that the optical path length from the original to the line photoelectric conversion element 24 is always kept constant. Drive at half speed. As a result, a reflection image from the original can be formed on the line photoelectric conversion element 24 at a constant magnification.

  By scanning the first and second traveling bodies 16 and 17 along the longitudinal direction of the housing 14, a predetermined range of the document placed on the contact glass 15 is sequentially illuminated linearly by the light source. . The reflected image reflected from the original is sequentially reflected by the first mirror 18, the second mirror 19 and the third mirror 20, and enters the line-type photoelectric conversion element 24. One line is output by the line-type photoelectric conversion element. Each time it is converted into an electrical signal and output as document image information.

  As shown in FIG. 2, the image reading unit 10 according to the present invention includes a plate-like base member 21 attached to the bottom wall 12 of the scanner device 11, and an imaging unit 22 that rises from an edge 21 a of the base member. .

  The imaging unit 22 has a support plate 22a fixed to the edge 21a of the base member 21 at the lower end via a holding member 23, and a reflection image provided on the support plate and reflected from the third mirror 20. The linear photoelectric conversion element 24 has a linear shape for reading each line and converting it into an electrical signal. The support plate 22a is fixed to the base member 21 via the holding member 23 by using, for example, an adhesive. In the illustrated example, the line-type photoelectric conversion element 24 is composed of three photoelectric conversion elements of R (red), G (green), and B (blue), and the respective longitudinal directions coincide with the X axis. Are arranged.

  Further, the image reading unit 10 includes an imaging lens system 25 for reducing the reflected image from the third mirror 20 provided on the second traveling body 17 and forming it on the line type photoelectric conversion element 24. . The imaging lens system 25 includes a plurality of lenses 26 (see FIG. 3) and two lens barrels 27 and 28 that are open at both ends and hold each lens 26 inside.

  In the illustrated example, each of the lens barrels 27 and 28 is a cylindrical body that is molded from a synthetic resin. In each of the lens barrels 27 and 28, in the example shown in FIG. 3, two lenses 26 are spaced apart from each other in the axial direction of the lens barrels 27 and 28, and the respective optical axes are set to the respective lens barrels 27. , 28 (FIG. 3 shows one lens barrel 27). In the example shown in the drawing, each lens 26 is constituted by a conventionally well-known lens group such as a bonded lens in which a plurality of lenses are bonded together.

  As shown in FIG. 2, the lens barrels 27 and 28 have their respective axes, that is, the optical axes of the lenses 26 fitted in the lens barrels 27 and 28 coincide with each other, and the optical axes of the lenses 26. Are arranged on the base member 21 at a distance from each other so as to be positioned at the center of the line-type photoelectric conversion element 24. In the illustrated example, the lens barrels 27 and 28 are held by the base member 21 via a pair of holding members 29 that come into contact with the outer peripheral surfaces 27a and 28a of the lens barrels 27 and 28, respectively. .

  In the example shown in the figure, the holding member 29 is made of an ultraviolet transmissive resin, and the base plate portion 30 attached to the base member 21 and the outer circumferences of the lens barrels 27 and 28 from the edge of the base plate portion. And an upright plate portion 31 that rises so as to abut against the surfaces 27a and 28a. Each base plate portion 30 and each upright plate portion 31 are bonded to the outer peripheral surfaces 27a and 28a of the base member 21 and the lens barrels 27 and 28, respectively, by an ultraviolet curable adhesive described later. Accordingly, the lens barrels 27 and 28 are fixed to the base member 21 via the holding members 29.

  In the illustrated example, of the two lens barrels 27, 28, the first lens barrel 27 located on the upstream side of the optical path from the original to the line-type photoelectric conversion element 24 includes the first lens mirror. A light shielding member 32 for correcting shading is provided in the opening 27b on the incident side of the reflected image into the cylinder.

  The light shielding member 32 has a circular shape, and is integrally formed integrally with the first lens barrel 27 in this embodiment. A window hole 33 for correcting the amount of light from the third mirror 20 is formed in the light shielding member 32. The window hole 33 extends in parallel to the line-type photoelectric conversion element 24, and in the illustrated example, the vertical width at the center of the window hole 33 is formed to be smaller than the vertical width at both ends of the window hole. Has been. As a result, the light shielding member 32 shields the light irradiated to the central portion of the light shielding member 32, that is, the light on the optical axis of each lens 26, compared to the light shielding amount irradiated to both ends of the light shielding member. Become more. The shading function of the light shielding member 32 corrects the decrease in the amount of peripheral light according to the cosine fourth law of each lens 26, and thereby the amount of light that passes through each lens 26 and enters the line-type photoelectric conversion element 24 becomes uniform. .

  A method for assembling the image reading unit 10 according to the present invention will be described.

  In assembling the image reading unit 10, first, the virtual optical axis of each lens 26 is set on the base member 21 disposed on the bottom wall 12 of the housing 14 of the scanner device 11. Next, the support plate 22a on which the line type photoelectric conversion element 24 is provided is held on the edge 21a of the base member 21 so that the center part in the extending direction of the line type photoelectric conversion element 24 is positioned on the virtual optical axis. 23 to fix. Further, the imaging lens system 25 is formed by fitting the lenses 26 into the lens barrels 27 and 28 so that the optical axes coincide with the axes of the lens barrels 27 and 28, respectively. The lens barrels 27 and 28 are arranged on the base member 21 so that the axes of the tubes 27 and 28, that is, the optical axes of the lenses 26 are substantially along the virtual optical axis. For example, an assembly robot (not shown) is used to arrange the lens barrels 27 and 28 on the base member 21.

  Thereafter, the first lens barrel 27 is aligned on the base member 21. That is, the first lens barrel 27 is placed on a plane including the Z axis and the base member 21 along the optical axis so that the optical axis of each lens 26 in the first lens barrel 27 coincides with the virtual optical axis. Are moved along the respective axes of the X axis perpendicular to the Z axis and the Y axis along the plate thickness direction of the base member 21, and around the X axis (the α direction in FIG. 2) and the Y axis. Around (in the β direction in FIG. 2).

  After axial alignment of the first lens barrel 27, the extension direction of the window hole 33 of the light shielding member 32 fixedly and integrally formed with the first lens barrel 27 is the extension direction of the line-type photoelectric conversion element 24. The first lens barrel 27 is rotated around the Z axis (in the γ direction in FIG. 2), that is, around the optical axis so as to coincide with. Thereby, the shading correction of the light shielding member 32 can be performed appropriately. Adjustment of the rotational posture of the light shielding member 32 and axial alignment of the first lens barrel 27 can be performed simultaneously.

  Further, the second lens barrel 28 is set to the first lens barrel 28 so that the optical axis of each lens 26 fitted in the second lens barrel 28 which is the other lens barrel 28 coincides with the virtual optical axis. In the same manner as the lens barrel 27, the lens barrel 27 is moved along the X axis, the Y axis, and the Z axis on the base member 21 and rotated in the α direction and the β direction.

  After the axial alignment of both the first and second lens barrels 27 and 28, as shown in FIG. 4, a line type photoelectric conversion element due to variation in imaging performance in the rotational direction around the optical axis of each lens 26 The second lens barrel 28 is rotated around the optical axis so that the region R in which the aberration of image formation to 24 is the smallest is parallel to the line-type photoelectric conversion element 24. Since the first lens barrel 27 and the second lens barrel 28 are formed separately from each other, when the second lens barrel 28 rotates around the optical axis, the second lens barrel 28 The first lens barrel 27 does not rotate around the optical axis with the rotation around the optical axis. Therefore, when the second lens barrel 28 rotates around the optical axis, the rotation posture of the light shielding member 32 fixedly and integrally formed with the first lens barrel 27 does not deviate from an appropriate rotation posture. Whether or not the aberration of image formation on the line type photoelectric conversion element 24 is within the standard is determined by processing and evaluating the image signal output from the line type photoelectric conversion element 24 using a signal processing circuit (not shown). Do. Thereby, the adjustment work of the first and second lens barrels 27 and 28 is completed.

  Thereafter, both the first and second lens barrels 27 and 28 that have been adjusted are fixed to the base member 21 with a pair of holding members 29. In order to fix the lens barrels 27 and 28 to the base member 21, the above-described ultraviolet curable adhesive is applied to the base plate portions 30 and the upright plate portions 31 of the holding members 29, respectively. Each holding member 29 is arranged so that 31 and each base plate portion 30 abut against the outer peripheral surfaces 27 a and 28 a of the lens barrels 27 and 28 and the base member 21, respectively. In this state, the ultraviolet curable adhesive applied to each holding member 29 is cured by irradiating each holding member 29 with ultraviolet rays using an ultraviolet irradiation device (not shown). The lens barrels 27 and 28 and the base member 21 are bonded. Adhesives other than the ultraviolet curable adhesive described above can be used for bonding the holding members 29 to the base member 21 and the lens barrels 27 and 28, but the positions of the lens barrels 27 and 28 whose positions have been adjusted are used. In order to quickly bond each lens barrel to the base member 21 without shifting, it is desirable to use the ultraviolet curable adhesive.

  By the adhesion of the holding members 29, the lens barrels 27 and 28 can perform appropriate shading correction and can minimize the aberration of image formation on the line type photoelectric conversion element 24. It is fixed to the base member 21 via each holding member 29. Thereby, the assembly of the image reading unit 10 is completed.

  According to the present embodiment, as described above, the light shielding member 32 for correcting the cosine fourth law of the lens 26 is fixedly and integrally formed on the first lens barrel 27. When the respective lenses 26 accommodated in the lens barrel 27 are aligned, the light shielding member 32 moves integrally with each lens 26 as in the prior art, so that the relative position between each lens 26 and the light shielding member 32 is displaced. It does not occur. This eliminates the need to readjust the rotational posture of the light shielding member 32 in accordance with the movement of each lens 26 and the rotation for axial alignment when each lens 26 is aligned, so that the conventional image reading unit 10 can be assembled. It is possible to reliably prevent an increase in man-hours.

  Further, as described above, since each lens 26 is held by separate lens barrels 27 and 28, the light shielding member 32 is fixed when correcting the aberration of image formation on the line photoelectric conversion element 24. The second lens barrel 28 can be rotated around the optical axis without rotating the first lens barrel 27 integrally formed with the optical axis. Accordingly, the second lens barrel 28 can be rotated around the optical axis while maintaining an appropriate posture of the light shielding member 32 with respect to the line type photoelectric conversion element 24, and thus the line type photoelectric conversion element of the light shielding member 32. Accordingly, the aberration of image formation on the line-type photoelectric conversion element 24 can be reliably reduced without degrading the shading effect due to the deviation of the posture with respect to 24 from the proper posture.

  Accordingly, the image reading unit 10 that can adjust the rotation of the lens 26 around the optical axis without causing a shift in the rotation posture of the light shielding member 32 with respect to the line photoelectric conversion element 24 and the scanner device 11 including the image reading unit are provided. Obtainable.

  Furthermore, as described above, the lens barrels 27 and 28 are formed of synthetic resin and divided into two parts. Therefore, compared to the conventional lens barrel in which all the lenses 26 are fitted, It is possible to reduce the weight of the lens barrel. Further, since the light shielding member 32 is fixedly integrally formed with the first lens barrel 27, the number of parts of the image reading unit 10 can be reduced, and the number of assembling steps of the image reading unit 10 can be reduced. Can be achieved.

<Example 2>
In the first embodiment, as described above, the example in which the light shielding member 32 for correcting the shading is fixed and integrally formed with the first lens barrel 27 has been described. The rotation posture of each lens 26 around the optical axis is held in the first lens barrel 27 so that the rotation posture of the lens 26 can be adjusted, and after adjusting the rotation posture of the light shielding member 32 with respect to the line type photoelectric conversion element 24, It can be fixed to the lens barrel 27.

  As shown in FIG. 5, the light shielding member 32 is formed with an annular fitting portion 32 a that allows fitting into the opening 27 b of the first lens barrel 27. The light shielding member 32 is formed with a window hole 33 similar to that described in the first embodiment. The light shielding member 32 is rotatably supported by the first lens barrel 27 through the fitting portion 32a.

  In the assembly of the image reading unit 10, as in the first embodiment, the support plate 22a provided with the line-type photoelectric conversion element 24 is fixed to the base member 21, and then the first and second lenses 26 are fitted. The second lens barrels 27 and 28 are arranged on the base member 21 using the assembly robot described above so that the optical axis of each lens 26 is substantially along the virtual optical axis set on the base member 21.

  Next, as in the first embodiment, the lens barrels 27 and 28 are moved along the X axis, Y axis, and Z axis, respectively, and rotated around the X axis and Y axis. As a result, the first and second lens barrels 27 and 28 are axially aligned.

  After the alignment of the lens barrels 27 and 28, the rotational posture of the light shielding member 32 is adjusted so that the shading correction by the light shielding member 32 can be properly performed. In other words, the first lens barrel 27 is held in a position such that the extending direction of the window hole 33 formed in the light blocking member 32 coincides with the extending direction of the line type photoelectric conversion element 24, and the light blocking member 32 is moved as shown in FIG. Around the Z axis, that is, around the optical axis of each lens 26.

  After that, as in the first embodiment, the aberration of image formation on the line type photoelectric conversion element 24 due to the variation in image formation performance with respect to the rotation direction around the optical axis of each lens 26 in the second lens barrel 28 is the highest. The second lens barrel 28 is moved along the optical axis while maintaining the posture of the first lens barrel 27 and the proper rotation posture of the light shielding member 32 so that the region R to be reduced becomes parallel to the line photoelectric conversion element 24. Rotate around. Since the first lens barrel 27 and the second lens barrel 28 are formed separately from each other, rotation of the second lens barrel 28 around the optical axis causes the first lens barrel 27 and the light shielding. The member 32 does not rotate around the optical axis.

  Further, instead of rotating the second lens barrel 28 around the optical axis, the first lens barrel 27 can be rotated around the optical axis while maintaining the proper rotation posture of the light shielding member 32. it can. Since the first lens barrel 27 is rotated while maintaining the appropriate rotation posture of the light shielding member 32, the rotation posture of the light shielding member 32 is appropriate due to the rotation of the first lens barrel 27 around the optical axis. Will not deviate from.

  Furthermore, both the first and second lens barrels 27 and 28 can be rotated around the optical axis. This makes it possible to correct the aberration of image formation on the line-type photoelectric conversion element 24 more finely than rotating either one of the lens barrels 27 and 28 around the optical axis.

  Whether the aberration of image formation on the line type photoelectric conversion element 24 is within the standard is determined by using a signal processing circuit (not shown) for the image signal output from the line type photoelectric conversion element 24 as in the first embodiment. It is done by processing and evaluating. Thereby, the adjustment operation of the first lens barrel 27, the second both lens barrels 28, and the light shielding member 32 is completed.

  Thereafter, the light shielding member 32 is fixed to the first lens barrel 27 in an appropriate rotation posture with respect to the line type photoelectric conversion element 24 by using, for example, the above-described ultraviolet curable adhesive. Similarly to the first embodiment, the lens barrels 27 and 28 are each fixed to the base member 21 via a pair of holding members 29 by using an ultraviolet curable adhesive, whereby the image reading unit 10. The assembly of is finished.

  According to the present embodiment, as in the first embodiment, the first lens barrel 27 is provided with the light shielding member 32 for correcting the cosine fourth power law of the lens 26. Since there is no need to readjust the rotational position of the light shielding member 32 according to the movement of each lens 26 and the rotation for axial alignment at the time of axis alignment, the number of assembling steps for the image reading unit 10 as in the conventional case is increased. It can be surely prevented.

  Further, as described above, since the light shielding member 32 is held by the first lens barrel 27 so that the rotational posture of each lens 26 around the optical axis can be adjusted, the image is formed on the line type photoelectric conversion element 24. When adjusting the aberration, the first and second lens barrels 27 and 28 are respectively rotated around the optical axis without rotating the light shielding member 32 provided on the first lens barrel 27 around the optical axis. Can be rotated. As a result, the lens barrels 27 and 28 can be rotated around the optical axis while maintaining an appropriate rotation posture of the light shielding member 32 with respect to the line photoelectric conversion element 24. The aberration of image formation on the line-type photoelectric conversion element 24 can be surely reduced without degrading the shading effect due to the rotation attitude with respect to the conversion element 24 deviating from an appropriate rotation attitude.

  Further, as described above, since both the lens barrels 27 and 28 can be rotated and adjusted around the optical axis, when only the second lens barrel 28 is rotated around the optical axis as in the first embodiment. The correction can be made more finely than the above. Thereby, the aberration of image formation on the line type photoelectric conversion element 24 can be further reduced.

<Example 3>
In the first and second embodiments, the example in which the image reading unit 10 according to the present invention is used in the scanner device 11 is shown. Instead, the image reading unit 10 according to the present invention is as shown in FIG. Further, the image forming apparatus 34 can be used in a copying machine 34.

  The copying machine 34 according to the present invention includes a scanner unit 35 for reading a document (not shown) to be copied, a plurality of sheet storage units 37 in which printing paper 36 is stored, and a sheet 36 from each of the sheet storage units. A paper feed unit 38 that operates to supply toner, an image forming unit 39 that forms a toner image on the paper 36 supplied by the paper feed unit based on an image signal from the image reading unit 10, and a toner image on the paper 36. A fixing unit 40 for fixing the toner image to the paper and a paper discharge unit 41 for discharging the paper 36 on which the toner image is fixed by the fixing unit.

  In the scanner unit 35, as described with reference to FIG. 2 in the first embodiment, a first lens barrel 27 and a second lens barrel in which a lens 26 (see FIG. 3) is fitted. 28, an image reading unit 10 that is fixedly and integrally formed with the first lens barrel 27 and includes a light shielding member 32 for correcting shading, and a line-type photoelectric conversion element 24 is used. As in the first embodiment, the light shielding member 32 is formed with a window hole 33 (see FIG. 2) extending in parallel with the line-type photoelectric conversion element 24. As the scanner unit 35, the image reading unit 10 including the light shielding member 32 of the second embodiment that is rotatably provided on the first lens barrel 27 can be used.

  The image reading unit 10 of the scanner unit 35 reduces the reflected image from the original placed on the contact glass 15 of the scanner unit 35 by both the first and second lens barrels 27 and 28 of the image reading unit 10. Then, an image is formed on the line type photoelectric conversion element 24 and converted into an electric signal by the line type photoelectric conversion element. As is well known, the image forming unit 39 forms a toner image on the surface of the photosensitive drum 42 based on the image information from the scanner unit 35, and the toner formed on the surface of the photosensitive drum 42. The image is transferred from the sheet storage unit 37 to the sheet 36 fed by the sheet feeding unit 38 by the transfer roller 43 and conveyed to the fixing unit 40. The fixing unit 40 fixes the toner image on the sheet 36 by heating and pressing the unfixed toner image on the sheet 36 conveyed from the image forming unit 39 between the fixing roller 44 and the pressure roller 45. The paper 36 on which the toner image has been fixed is discharged by a paper discharge unit 41 from a paper discharge port 47 formed in the housing 46 of the copying machine 34 to a tray 48 provided outside the housing 46.

  According to the present embodiment, by applying the image reading unit 10 according to the present invention to the image forming apparatus 34, the light shielding member 32 is rotated with respect to the line-type photoelectric conversion element 24 by the same assembly as the first or second embodiment. It is possible to obtain the image forming apparatus 34 including the image reading unit 10 that can rotate and adjust the lens 26 around the optical axis without causing a deviation in posture.

  In the first to third embodiments, the base member in which the first lens barrel 27, the second lens barrel 28, and the line-type photoelectric conversion element 24 are provided on the bottom wall 12 of the housing 14 of the scanner device 11. However, instead of this, a part of the bottom wall 12 is constituted by the base member 21, and the first lens barrel 27, the second lens barrel 28, and the line type photoelectric conversion element. Each of the 24 can be fixed directly to the bottom wall 12. Thereby, since the number of parts of the scanner device 11 is reduced, the number of assembling steps of the scanner device 11 can be reduced.

  In the first to third embodiments, the example in which the two lens groups (26) are fitted in the lens barrels 27 and 28, respectively. , 28 can be fitted with one lens group (26) or three or more lens groups (26), respectively. Moreover, although the example which used the lens group for each lens 26 was shown, it replaces with this and all of these each lens groups or its arbitrary lens groups can be comprised with a single lens.

  Furthermore, the example in which the light shielding member 32 is provided in the opening 27b on the incident side of the light into the lens barrel 27 of the first lens barrel 27 is shown, but instead, for example, the first lens mirror The light shielding member 32 can be provided in the opening of the tube 27 on the light emission side from the lens barrel or in each opening of the second lens barrel 28.

1 is an exploded perspective view schematically showing a scanner device according to the present invention. 1 is a perspective view schematically showing an image reading unit according to the present invention. 1 is a longitudinal sectional view schematically showing a lens barrel according to the present invention. It is a front view which shows roughly the relationship between the lens which concerns on this invention, and a line type photoelectric conversion element. It is a longitudinal cross-sectional view which shows schematically the state by which the light shielding member which concerns on Example 2 was rotatably hold | maintained at the lens barrel. FIG. 10 is a perspective view schematically illustrating a copying machine according to a third embodiment.

Explanation of symbols

24 line type photoelectric conversion element 26 lens 27, 28 lens barrel 21 base member 32 light shielding member 10 image reading unit 11 scanner device 14 housing 34 image forming apparatus (copier)

Claims (8)

  Arranged are at least two lenses for reducing and forming a reflection image from a document on a line-type photoelectric conversion element, a lens barrel for holding each lens, the lens barrel and the line-type photoelectric conversion element. An image reading unit comprising: a base member, wherein one of the lens barrels is provided with a light shielding member for correcting a cosine fourth law of the lens.   The image reading unit according to claim 1, wherein the one lens barrel is made of resin, and the light shielding member is integrally formed with the one lens barrel.   2. The image reading unit according to claim 1, wherein the light shielding member is fixed to the one lens barrel after adjusting the rotational posture around the optical axis of the one lens barrel.   A scanner apparatus comprising the image reading unit according to any one of claims 1 to 3.   The scanner device according to claim 4, comprising a housing, wherein a part of the housing is configured by the base member.   An image forming apparatus comprising the image reading unit according to claim 1.   Arranged are at least two lenses for reducing and forming a reflection image from a document on a line-type photoelectric conversion element, a lens barrel for holding each lens, the lens barrel and the line-type photoelectric conversion element. A method of assembling an image reading unit, wherein a light shielding member for correcting a cosine fourth law of the lens is fixed to one lens barrel, the position of the one lens barrel In order to correct the aberration of image formation on the line-type photoelectric conversion element, the other lens barrel is rotated around the optical axis, and then the other lens barrel is attached to the base member. An assembling method of an image reading unit characterized by fixing.   Arranged are at least two lenses for reducing and forming a reflection image from a document on a line-type photoelectric conversion element, a lens barrel for holding each lens, the lens barrel and the line-type photoelectric conversion element. And a light shielding member having a window hole for correcting the cosine fourth law of the lens is rotatably held around the optical axis of the lens. In the assembling method, after adjusting the rotation posture of the light shielding member provided on the one lens barrel with respect to the line type photoelectric conversion element, to correct aberration of image formation on the line type photoelectric conversion element In addition, the one lens barrel provided with at least the light-shielding member of the two lens barrels is held in the optical axis while maintaining the rotational posture of the light-shielding member with respect to the line photoelectric conversion element. After rotating around the respective lens barrel is fixed to each of the base member, then, the assembly method of the image reading unit, characterized in that for fixing the light shielding member to the lens barrel of the one.

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