JP2008216322A - Power source, image reader, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source for main scanning a document in lines by a plurality of LED devices arrayed in lines, the light source being designed to reduce nonuniform quantity of light on reading lines by providing a light quantity adjusting plate between the LED devices and the reading lines. <P>SOLUTION: The plurality of LED devices 11 are arrayed at prescribed pitches on a substrate 12 that is long in a main scanning direction. The light quantity adjusting plate 60 that is long in the main scanning direction is disposed between the plurality of LED devices 11 and the reading lines of an image face. Light quantity adjusting widows 62 that are long in the main scanning direction are made in the widthwise center of the light quantity adjusting plate 60. The window width a of a portion 62a, corresponding to each LED device 11, of each of the light quantity adjusting windows 62 is made narrower than the window width b of a portion 62b corresponding to an inter-element intermediate between the two adjacent LED elements 11. This reduces nonuniform quantity of light on the reading lines. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light source configured by aligning a plurality of light source elements as point light sources in a line, an image reading apparatus including the light source, and an image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, an image reading apparatus is used to read an image of a document. This image reading apparatus sub-scans the light source or the document in a direction perpendicular to the main scanning direction while main-scanning the image surface with a rod-shaped light source such as a xenon lamp or a halogen lamp, and reflects and reflects the reflected light from the document. The entire image plane is read by being guided to an image sensor such as a CCD through an image lens.

  Patent Document 1 proposes such an image reading apparatus in which a light source is configured by a plurality of light source elements (point light sources) instead of a rod-shaped one.

In this device, a light source is constituted by a plurality of light source elements arranged in parallel to the main scanning direction which is the reading direction of the line sensor. Thereby, the non-uniformity in the amount of light can be eliminated, a compact configuration can be achieved, and the quality of the copy image can be improved by eliminating a partially generated black image (shadow).
JP 2002-314760 A

  However, when a light source is configured by aligning a plurality of light source elements in the main scanning direction, the light amount unevenness is likely to occur on the irradiated surface, unlike a conventional bar light source such as a xenon lamp or a halogen lamp. There is a problem, and this unevenness in the amount of light has a problem that the image reading result by the image reading apparatus and the image forming result by the image forming apparatus are adversely affected. In general, when an irradiation surface is irradiated in a line shape by a plurality of light source elements, there is a tendency that light and shade are alternately generated along the line. This shading tends to brighten the part corresponding to the light source element and darken the part corresponding to the middle of two adjacent light source elements. Such problems can be dealt with to some extent by controlling the amount of light for each light source element or correcting the reading result by the CCD in the image reading apparatus for each pixel. is there. However, in this case, it is necessary to perform complicated control and correction.

  Accordingly, an object of the present invention is to provide a light source, an image reading apparatus, and an image forming apparatus that can suppress light source unevenness while having a simple configuration that does not require complicated control.

  The invention according to claim 1 relates to a linear light source that irradiates an image surface of a document in a main scanning direction. A light source according to the present invention includes a plurality of light source elements aligned in the main scanning direction, a substrate for holding the plurality of light source elements in an aligned state, and supplying power to the plurality of light source elements, and the plurality of light source elements. A light amount adjusting member disposed between the light source element and the image plane, the light amount adjusting member being disposed along the main scanning direction and being long in the main scanning direction, wherein the light amount adjusting member includes the plurality of light source elements. A light amount adjustment window that is long in the main scanning direction, through which light that is emitted from the image plane passes, and the light amount adjustment window corresponds to an intermediate portion between two light source elements adjacent to each other Is set larger than the window width of the element corresponding portion corresponding to the light source element.

  According to a second aspect of the present invention, in the light source according to the first aspect, the light amount adjustment window is such that the window width gradually decreases from the element corresponding part toward the element corresponding part.

  According to a third aspect of the present invention, in the light source according to the second aspect, a peripheral edge located between the element corresponding part and the inter-element corresponding part in the peripheral edge of the light amount adjustment window is formed linearly. It is characterized by that.

  The invention according to claim 4 is the light source according to claim 2, wherein a portion located in the vicinity of the element corresponding portion in the periphery of the light amount adjustment window is formed with a gentle curve convex toward the inside, A portion located in the vicinity of the element interfacing portion is characterized by being formed with a gentle curve concave toward the inside.

  According to a fifth aspect of the present invention, in the light source according to any one of the first to fourth aspects, the light source includes a first adjustment mechanism that adjusts a position of the light amount adjustment member with respect to the substrate.

  According to a sixth aspect of the present invention, in the light source according to any one of the first to fifth aspects, the light amount adjusting member has a surface that faces the image surface around the light amount adjusting window and has a low reflectance. It is characterized by being.

  According to a seventh aspect of the present invention, in the light source according to any one of the first to fifth aspects, the light amount adjusting member has a surface facing the light source element around the light amount adjusting window formed with a low reflectance. It is characterized by being.

  In the invention according to claim 8, the image surface of the document is main-scanned by a long line-shaped light source, and the light source or the document is moved in the direction orthogonal to the main-scanning direction to perform sub-scanning. The present invention relates to an image reading apparatus that guides reflected light that is emitted and reflected by the image surface of the document to a fixed imaging element through an imaging lens. The image reading apparatus according to the present invention is characterized in that the light source is the light source according to any one of claims 1 to 7.

  According to a ninth aspect of the present invention, in the image reading apparatus according to the eighth aspect, a moving frame that supports the light source and moves in the sub-scanning direction, and a second adjustment that adjusts an inclination of the light source with respect to the moving frame. It has a mechanism.

  According to a tenth aspect of the present invention, an image reading unit that reads an image of a document, an image forming unit that forms an image on a sheet based on image information of the document read by the image reading unit, and the image forming unit The present invention relates to an image forming apparatus including a sheet feeding unit that supplies sheets. The image forming apparatus according to the present invention is characterized in that the image reading device according to claim 8 or 9 is disposed in the image reading section.

  According to the first aspect of the present invention, the light emitted from the plurality of light source elements aligned in the main scanning direction passes through the element corresponding portion rather than the inter-element facing portion when passing through the light amount adjustment window. Therefore, when the light reaches the image plane, the amount of light is adjusted in the main scanning direction, and unevenness in the amount of light is suppressed.

  According to the second aspect of the present invention, the window width of the light amount adjustment window gradually decreases from the inter-element corresponding portion toward the element corresponding portion. As compared with the case where there is no element, the amount of light that is reduced gradually increases from the corresponding part between elements toward the corresponding part.

  According to the invention of claim 3, the window width of the light quantity adjustment window is set between the elements by linearly forming the peripheral edge between the element corresponding part and the inter-element corresponding part at the peripheral edge of the light quantity adjustment window. It is gradually decreased from the corresponding part toward the element corresponding part. According to this, since the shape of the light quantity adjustment window becomes simple, the production of the light quantity adjustment member is easy.

  According to the invention of claim 4, the portion located in the vicinity of the element corresponding portion on the periphery of the light amount adjustment window is formed with a gentle curve convex toward the inside, and is located in the vicinity of the element fitting portion. By forming the portion with a gentle curve concave toward the inside, the window width of the light amount adjustment window is gradually reduced from the inter-element corresponding portion toward the element corresponding portion. According to this, although the shape of the light amount adjustment window is complicated, the unevenness of the light amount can be made more uniform.

  According to the fifth aspect of the present invention, the position of the light amount adjusting member (for example, the position and inclination in the main scanning direction) can be adjusted with respect to the substrate by the first adjusting mechanism, so that the image plane is formed in a line shape When irradiated, the difference in light quantity between one end and the other end can be reduced.

  According to the sixth aspect of the present invention, the surface facing the image surface around the light amount adjustment window is formed with a low reflectance, so that flare light reflected by the surface facing the image surface is prevented and stabilized. Light amount correction can be performed.

  According to the seventh aspect of the present invention, the surface facing the light source element around the light amount adjustment window is formed with a low reflectance, so that flare light reflected by the surface facing the high element is prevented and stabilized. Light amount correction can be performed.

  According to invention of Claim 8, the effect of the above-mentioned light source can be show | played as an image reading apparatus. That is, it is possible to prevent image reading failure due to unevenness in the amount of light.

  According to the ninth aspect of the invention, since the inclination of the entire light source with respect to the moving frame can be adjusted by the second adjustment mechanism, one end and the other when the image surface is irradiated in a line shape The difference in the amount of light from the end of the can be reduced.

  According to the invention of claim 10, the effect of the above-described image reading apparatus can be exhibited as an image forming apparatus. That is, it is possible to prevent an image defect caused by an image reading defect caused by unevenness in the amount of light.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
With reference to FIG. 1, an image forming apparatus 1 according to the present invention including an image reading device 7 according to the present invention will be described. FIG. 1 is a schematic view of the image forming apparatus 1 as viewed from the front side (the side on which the user is located when using the image forming apparatus 1). Here, examples of the image forming apparatus 1 include a copying machine, a printer, a facsimile machine, and a multi-function machine thereof. In the following, a case where the image forming apparatus 1 is a printer will be described as an example.

  As shown in FIG. 1, the image forming apparatus 1 includes a sheet feeding unit 2, an image forming unit 3, a fixing unit 4, a sheet discharge unit 5, and an image reading unit 6.

  The sheet feeding unit 2 includes a sheet feeding cassette 2a, a sheet feeding roller 2b, a feeding roller 2c, a retard roller 2d, a conveying roller pair 2e, and a registration roller pair in order from the upstream side in the conveying direction of the sheet P. 2f etc. are arranged. The plurality of sheets P stored in a stacked state in the sheet feeding cassette 2a are fed by the sheet feeding roller 2b and are prevented from being double fed by the feeding roller 2c and the retard roller 2d. Only one sheet is fed downstream. Further, the conveying roller pair 2e is brought into contact with the stopped registration roller pair 2f to correct skew. Thereafter, the sheet P is supplied to the image forming unit 3 so as to be synchronized with the toner image formed on the photosensitive drum 3 a of the image forming unit 3.

  The image forming unit 3 includes a photosensitive drum 3a, a charging roller 3b, an exposure device 3c, a developing device 3d, a transfer roller 3e, a cleaning device 3f, and the like. The photosensitive drum 3a is rotationally driven in the direction of the arrow (clockwise), and the surface thereof is uniformly charged to a predetermined polarity and potential by the charging roller 3b. The charged photosensitive drum 3a is exposed by the exposure device 3c, and the charge of the exposed portion is removed to form an electrostatic latent image. This exposure is performed based on image information of a document read by an image reading device 7 described later. The electrostatic latent image formed on the photosensitive drum 3a is developed as a toner image with toner attached thereto by the developing device 3d. This toner image is transferred to the sheet P supplied from the sheet feeding unit 2 at a transfer nip formed between the photosensitive drum 3a and the transfer roller 3e. After the toner image is transferred, the toner (transfer residual toner) remaining on the surface of the photosensitive drum 3a is removed by the cleaning device 3f and used for the next image formation.

  The fixing unit 4 is provided with a fixing roller 4a and a pressure roller 4b. The fixing roller 4a is heated by a heater (not shown) and rotates in the arrow direction (counterclockwise). On the other hand, the pressure roller 4b is pressed by the fixing roller 4a to form a fixing nip portion with the fixing roller 4a. The sheet P on which the toner image has been transferred to the surface by the image forming unit 3 is heated and pressurized when passing through the fixing nip portion, and the toner image is fixed on the surface.

  The sheet discharge unit 5 is provided with a discharge roller pair 5a and a discharge tray 5b. The sheet P after the toner image is fixed is discharged onto the paper discharge tray 5b by the paper discharge roller pair 5a.

  An image reading device 7 is disposed in the image reading unit 6. The image reading device 7 presses a document (see FIG. 6) placed on the contact glass 18 with the image surface facing downward from above by a document pressing plate 19 to bring the image surface into close contact with the contact glass 18, which will be described later. The image surface is irradiated by the light source 10 and the image is read based on the reflected light at that time.

  The image reading device 7 will be described with reference to FIGS. However, in these drawings, the document pressing plate 19 is not shown. 2 to 5 are views of the longitudinal section of the image reading device 7 as seen from the front side (front side), FIG. 2 shows the optical system, and FIG. 3 shows the drive system. FIG. 4 and 5 are top views for explaining the relationship between the light source 10, the size of the document, and the position of the document at the time of image reading. Further, FIG. 4 shows the case where the document size is A column and B column. FIG. 5 shows a case where the document size is an inch size. In the following description, the left and right in FIGS. 2 to 5 are the left and right of the image reading device 7, the top and bottom in FIGS. 2 and 3 are the top and bottom of the image reading device 7, and FIGS. The bottom and top in the middle will be described as before and after the image reading device 7, respectively. Further, the length in the vertical direction of the document in FIGS. 4 and 5 is referred to as the sheet passing width (or simply “width”), and the length in the left and right direction is referred to as the conveyance direction length (or simply “length”).

  As shown in FIG. 3, the image reading device 7 includes an illumination device 8, an imaging lens 13, and a CCD (solid-state imaging device) 14. Further, the lighting device 8 includes a light source 10 and a driving device (moving device) 15. The light source 10, the driving device 15, the illumination device 8, the imaging lens 13, and the CCD 14 are all disposed inside a rectangular parallelepiped housing (frame) 16. The housing 16 has an opening 17 on its upper surface, and a transparent contact glass 18 is disposed in the opening 17. An openable / closable document pressing plate 19 (see FIG. 1) is disposed above the contact glass 18. In the closed state, the document pressing plate 19 presses a document placed on the contact glass 18 against the upper surface of the contact glass 18 from above. On the other hand, in the open state, a document can be placed on the contact glass 18 and the document placed on the contact glass 18 can be removed.

  As shown in FIGS. 4 and 5, the contact glass 18 is formed in a rectangular shape that is larger than the largest original among the sheet-like originals placed on the upper surface thereof. In the contact glass 18, a left indicator plate 20 that is long in the front-rear direction is provided at the left end, and a rear indicator plate 21 and a front indicator plate 22 that are long in the left-right direction are provided at the rear end and the front end, respectively. A position where the rear end of the left indicating plate 20 and the left end of the rear indicating plate 21 intersect is a reading reference position P01. The document placed on the contact glass 18 is positioned at one corner, that is, a corner (reference corner) located at the left end and the rear end at a position (predetermined position) that matches the reading reference position P01. Placed. In FIGS. 4 and 5, originals of various sizes are illustrated in a state in which the reference corner is aligned with the reading reference position P01. Here, the size and orientation of each original are displayed at positions corresponding to the diagonals of the reference corners in the originals of each size. For example, B5 and A4 in FIG. 4 indicate the position of the original when the “long side” of each original is aligned with the left indicating plate 20. Hereinafter, this is referred to as “horizontal placement” of the manuscript. B5R and A4R indicate the position of the original when the “short side” of each original is aligned with the left indicating plate 20. Hereinafter, the “R” attached is referred to as “vertical placement” of the document and is distinguished from “horizontal placement”. According to this, “B4” and “A3” in FIG. 4 should originally be expressed as “B4R” and “A3R”, but originals of these sizes can be placed horizontally. In other words, only one way of placement is possible and there is no need to distinguish between them.

  The notations such as “B5”, “B5R”, “A4”, “A4R”, “B4”, “A3”, etc. are not actually shown on the contact glass 18 but on the left indicator plate 20 and the rear indicator plate 21. Has been. For example, “B5R”, “A4R”, “B5, B4”, and “A4, A3” are written in this order at the positions indicated by reference signs P1, P2, P3, and P4 on the left indicating plate 20. On the other hand, the positions indicated by reference signs P5, P6, P7, and P8 on the rear indicating plate 21 are labeled “B6R, B5”, “A5R, A4”, “B5R”, and “A4R” in this order. Thus, the user can know the document size and orientation when the document is placed at a predetermined position on the contact glass 18. Therefore, for example, when an image is formed on a sheet of paper or the like by a copying machine or a printer based on the image reading result of the document, it is a reference when selecting the size and orientation of the sheet used for image formation. It can be. In FIG. 5, the document size is displayed in inches. The width slightly larger than the sheet passing width of “A4, A3” in the contact glass 18 in FIG. 4 is the maximum image reading width (maximum irradiation width), and “11 × 17” in the contact glass 18 in FIG. The range slightly longer than the conveyance length of “” is the maximum image reading length (maximum irradiation length). The light source 10 to be described later can irradiate the entire maximum reading area surrounded by the maximum reading width and the maximum reading length.

  As shown in FIGS. 2 to 5, an illumination optical movement frame unit 23 is disposed below the left end side of the contact glass 18. The illumination optical movement frame unit 23 has a movement frame 24 having a length in the front-rear direction longer than the above-described maximum reading width. A light source 10, a concave mirror 26, and a first mirror 27 are mounted on the moving frame 24. 4 and 5, the light source 10 includes a substrate 12 formed such that the length in the front-rear direction is longer than the maximum reading width, and a light source element (point light source) attached to the upper surface thereof. ) As a plurality (22 in this embodiment) of LED elements 11 and a light amount adjusting plate 60 described later. In addition, in the following description, when distinguishing the LED element 11, it describes with LED element L1-L22. The LED elements 11 (L1 to L22) are arranged in a line in the front-rear direction. Here, the line shape is not limited to a case where the lines are aligned on a single straight line, but includes, for example, a case where the lines are aligned in a staggered pattern and are substantially linear. These LED elements L1 to L22 are aligned at a predetermined pitch P (for example, 15 mm in the present embodiment) that can irradiate the image surface of the original without unevenness in the amount of light along the line direction (front-rear direction). 4 and 5, the distance from the center of the rearmost LED element L1 to the center of the frontmost LED element L22 is set to 315 mm (= 15 mm × 21). In the example shown in FIG. 4, the long side (= 297 mm) of the A4 size document having the maximum sheet passing width or the short side (= 297 mm) of the A3 size document is inserted between L22 and FIG. In the example shown in FIG. 5, the long side or the short side is set so that the long side or the short side of the document having an 11-inch (≈279 mm) length is included. As shown in FIG. 2, the light source 10 constituted by the plurality of LED elements L1 to L22 and the substrate 12 irradiates the reading line L set on the upper surface of the contact glass 18 from the lower right side. Yes.

  As shown in FIG. 2, the concave mirror 26 is disposed at a position that is substantially line-symmetric with the light source 10 described above with respect to the perpendicular h that is lowered from the reading line L. As described above, since the light source 10 irradiates the document on the contact glass 18 obliquely from the lower right, a shadow is formed at the left end of the document, and this shadow tends to be read as an image on a straight line in the front-rear direction. It is. The concave mirror 26 reflects light from the light source 10 and guides it to the reading line L to remove this shadow. A first mirror 27 is disposed in a portion of the illumination optical movement frame unit 23 located immediately below the reading line L. The first mirror 27 is attached in a state in which 45 degrees on the upper left is turned. As described above, the illumination optical moving frame unit 23 can move in the left-right direction along the guide member 25 laid in the left-right direction with the light source 10, the concave mirror 26, and the first mirror 27 mounted on the moving frame 24. . That is, it is possible to move in a direction orthogonal to the linear (linear) light source 10. The illumination optical moving frame unit 23 emits light from the light source 10 toward the reading line L while moving to the right, and guides reflected light from the image surface of the document to a second mirror 28 described below. It is.

  As shown in FIGS. 2 and 3, below the left end side of the contact glass 18, a reflection optical moving frame unit 30 is disposed on the left side of the above-described illumination optical moving frame unit 23. The reflective optical moving frame unit 30 has a moving frame 31 that is longer in the front-rear direction than the above-described maximum reading width. A second mirror 28 is mounted on the moving frame 31 with 45 degrees tilted right downward, and a third mirror 32 is mounted with 45 degrees tilted right upward. Further, the moving frame 31 rotatably supports the movable pulley 33 at its front end and rear end. As described above, the reflecting optical moving frame unit 30 can move in the left-right direction along the guide member 25 laid in the left-right direction with the second mirror 28, the third mirror 32, and the movable pulley 33 mounted thereon. It is like that. The optical movement frame unit 30 for reflection reflects light from the first mirror 27 of the optical movement frame unit 23 for illumination described above by the second mirror 28 and the third mirror 32 while moving to the right. It leads to the imaging lens 13.

  As shown in FIG. 3, fixed left pulleys 34 and 34 are provided at the front and rear ends in the vicinity of the left end of the housing 16, and fixed right pulleys 35 and 35 are provided at the front and rear ends in the vicinity of the right end of the housing 16. Are rotatably arranged. Further, a motor 36 capable of rotating in the forward and reverse directions is disposed below the fixed right pulleys 35 and 35 in FIG. Further, a drive pulley 38 that is integral with the drive shaft 37 is disposed on the left side of the motor 36, and a drive belt 41 is stretched between the output shaft 40 of the motor 36 and the drive pulley 38. Yes. Wire drums 42 and 42 are fixed to the front end and the rear end of the drive shaft 37, and optical wires 43 and 43 are wound around the wire drums 42 and 42, respectively. One end portions 44 of the optical wires 43 are fixed to the inner surface of the left side wall 45 of the housing 16. The optical wires 43, 43 extend rightward from here, hang around the right half of the movable pulleys 33, 33 of the reflecting optical moving frame unit 30, are folded back leftward, and left of the fixed left pulleys 34, 34. After being stretched over the half, it is folded rightward and extends toward the fixed right pulleys 35 and 35. Further, it is stretched to the left half of the fixed right pulleys 35 and 35 and extends to the left. After being fixed to the illumination optical movement frame unit 23 in the middle, it further extends to the left and the movable pulleys 33 and 33 It is stretched over the left half, folded back to the right, and locked to a hook 47 protruding on the lens mount 46. When the motor 36 rotates counterclockwise in FIG. 3 based on the routing of the optical wires 43, 43, the wire drums 42, 42 are also anti-clockwise via the drive belt 41, the drive pulley 38, and the drive shaft 37. Rotate clockwise. Along with this, the illumination optical movement frame unit 23 and the reflection optical movement frame unit 30 move to the right by being pulled by the optical wires 43 and 43. At this time, since the movable pulleys 33 and 33 of the reflecting optical moving frame unit 30 act as a so-called moving pulley, the moving distance becomes half of the moving distance of the illumination optical moving frame unit 23. Thereby, regardless of the movement of the illumination optical movement frame unit 23 and the reflection optical movement frame unit 30, the optical path length from the contact glass 18 to the imaging lens 13 (the length of the optical path K) is kept constant, The light that has passed through the imaging lens 13 described below forms an image on the CCD 14. In the present embodiment, the entire configuration for moving the light source 10 as described above corresponds to a driving device (moving device).

  As shown in FIG. 3, the imaging lens 13 is fixed on a lens mounting plate 48 fixed to the lens mounting base 46 described above. The light emitted from the light source 10 is reflected by the image surface of the document and follows the optical path K shown in FIG. That is, the reflected light from the image surface is reflected by the first mirror 27, the second mirror 28, and the third mirror 32 and is incident on the imaging lens 13. The incident light is imaged on the CCD 14 described next.

  The CCD 14 is attached to a “U” -shaped CCD adjustment plate 52 that is fixed to the above-described lens mounting base 46 via a CCD mounting plate 51 that is fixed to the left end surface and the upper end portion 50 is bent to the left. ing. Bosses 53 and 53 having internal threads threaded on the inner diameter are fixed to the front end portion and the rear end portion of the CCD adjustment plate 52, and the upper end portion 50 of the CCD mounting plate 51 is attached to these bosses 53 and 53. The penetrated pins 54 and 54 are screwed together. Further, compression springs 55 and 55 are interposed between the CCD mounting plate 51 and the CCD adjustment plate 52 to urge the CCD mounting plate 51 upward. In this state, the height position of the CCD 14 can be finely adjusted via the CCD mounting plate 51 by turning the pins 54 and 54 clockwise or counterclockwise. By performing this fine adjustment at the front end and the rear end of the CCD 14, the vertical position adjustment of the CCD 14 can be performed.

  FIG. 6 schematically shows an outline of the image reading apparatus 7 described with reference to FIGS. As shown in the figure, the image reading device 7 scans the original G placed on the contact glass 18 along the reading line L by the light source 10 while performing the illumination optical movement frame unit 23 and the reflection optical. Scanning is performed in the sub-scanning direction by moving the moving frame unit 30 to the right. As a result, the entire image surface of the original G can be scanned, and the reflected light at this time is guided to the CCD 14 via the imaging lens 13 by the first mirror 27, the second mirror 28, and the third mirror 32. Thereby, the image of the original G can be read. Based on the read result, an electrostatic latent image is formed on the photosensitive drum 3a by the above-described exposure device 3c.

  In FIG. 7, the irradiation angle α of the LED elements 11 (L1 to L22) and the pitch P between the centers of the adjacent LED elements 11 and the distance H from the light emitting surface of the LED elements 11 to the reading line (image surface) L are shown. Show the relationship. The incident angle α is an angle corresponding to a solid angle of a portion where the light amount is halved when the light emitted from the light emitting surface of the LED element 11 irradiates the reading line L. In addition, the distance H to the reading line L refers to the distance between the reading line L and the center of the light emitting surface at the normal line standing at the center of the light emitting surface of the LED element 11. As shown in FIG. 7, the light emitted from the LED element 11 irradiates the reading line L with the irradiation angle α. For this reason, light amount unevenness as shown in FIG. That is, the portion corresponding to the LED elements L1, L2, L3,... Has a large amount of light, while the portion corresponding to the middle of the adjacent LED elements has a small amount of light. That is, shading (orientation unevenness) occurs corresponding to the pitch of the LED elements L1, L2, L3,. For this reason, when an image having the same density is read, the amount of light received by the CCD 14 (see FIG. 2) is not uniform, and as a result, the image formed by the image forming apparatus 1 shown in FIG. Become.

  Therefore, in the present embodiment, unevenness in the amount of light on the reading line L when the reading line L is irradiated by the LED elements L1, L2, L3,. Hereinafter, this point will be described in detail.

  The light source 10 according to the present embodiment will be described with reference to FIGS. 9 is an enlarged view of the vicinity of the light source 10 in FIG. 1 or FIG. FIG. 10 is a view of the light source 10 in FIG. 9 as viewed from the reading line L side.

  As shown in these drawings, the light source 10 includes the above-described plurality of LED elements 11 (L1 to L22) and the substrate 1 that holds the LED elements 11 and, in addition, a light amount adjusting plate (light amount adjusting member) 60. I have. The light amount adjustment plate 60 is formed long in the main scanning direction, and its longitudinal direction (both ends in the front-rear direction) is supported by support members 61 erected on both ends in the front-rear direction of the illumination optical movement frame unit 23, respectively. It is supported. As shown in FIG. 10, the light amount adjustment plate 60 is disposed between the plurality of LED elements 11 and the reading line L so as to be parallel to the substrate 12. In other words, the light amount adjustment plate 60 is disposed so as to cover the plurality of LED elements 11 at positions slightly away from them. A light amount adjustment window 62 that is long in the main scanning direction is formed in the light amount adjusting plate 60 at the center in the width direction (a direction orthogonal to the longitudinal direction that is the main scanning direction). In the present embodiment, the light amount adjustment window 62 is alternately provided with a portion with a narrow window width (dimension in the sub-scanning direction) and a wide portion along the main scanning direction. That is, the light amount adjustment window 62 has a narrow window width a in the element corresponding portion 62a corresponding to each LED element 11, and corresponds to the middle of the two LED elements 11 and 11 adjacent to each other. The window width b in the inter-element corresponding portion 62b, which is a portion to be formed, is formed to be wide. Further, the window width is gradually reduced from the inter-element corresponding portion 62b toward the element corresponding portion 62a. In the present embodiment, the peripheral edge 62c located between the element corresponding part 62a and the inter-element corresponding part 62b in the peripheral edge 62c of the light amount adjustment window 62 is formed in a gentle curved shape. That is, a portion of the peripheral edge 62c of the light amount adjustment window 62 that is positioned in the vicinity of the element corresponding portion 62a is formed by a gentle curve that is convex inward, and is a portion that is positioned in the vicinity of the element fitting portion 62b. However, these curved lines, which are formed with gentle concave curves inward, are connected between the element corresponding part 62a and the element corresponding part 62b.

  In the present embodiment, the light amount adjusting plate 60 reflects light on the surface 60 b facing the reading line L (the surface facing the image surface) 60 a and the surface 60 b facing the LED element 11 around the light amount adjusting window 62. The rate is configured to be low. For example, the reflectance is kept low by performing matte black coating. Thereby, flare light reflected by these surfaces 60a and 60b can be prevented, and stable light quantity correction can be performed.

  According to the light source 10 described above, the light amount adjustment window 62 which is long in the main scanning direction is provided, and the window width b of the inter-element corresponding portion 62b corresponding to the middle of the two LED elements 11 adjacent to each other is It was made larger than the window width a of the element corresponding part 62a corresponding to the LED element 11. Thereby, when the light emitted from the plurality of light source elements 11 passes through the light amount adjustment window 62, the light passing through the element corresponding part 62a is more concentrated than the inter-element facing part 62b. When reaching L, the amount of light is adjusted in the main scanning direction, and unevenness in the amount of light is suppressed. This is shown in FIG. As shown in the figure, it can be seen that the light amount unevenness is reduced in the entire main scanning direction as compared with FIG. Further, since the peripheral edge 62c of the light amount adjustment window 62 is formed in the curved shape as described above, it is possible to further level the unevenness of the light amount as compared with the case where this is a linear shape. Even when the element corresponding part 62a and the element corresponding part 62b are formed so as to be connected in a straight line, the unevenness in the amount of light can be leveled to some extent. In the case of a straight line, since the configuration is simple compared to the case of a curved line, the light quantity adjustment plate 60 can be easily manufactured.

  As another embodiment, an example in which the position of the light amount adjustment plate 60 can be adjusted will be described with reference to FIGS. Among these drawings, (a) is a view seen from the front side, and (b) is a view seen from the right side. As shown in FIG. 4A, the light amount adjusting plate 60 is formed such that its left end side and right end side hang downward, while the board mounting plate 65 is erected on its left end side and right end side. Is formed. As shown in FIG. 5B, a first adjustment mechanism 74 is disposed on the front end side of the light amount adjustment plate 60. A support portion 66 constituting a part of the first adjustment mechanism 74 is suspended from the front end side of the light amount adjustment plate 60. On the upper side of the outer surface of the support portion 66, a positioning pin 67 protrudes outward, and on the lower side, a female screw portion 68 is provided. On the other hand, a support portion 70 is erected on the front end side of the board mounting plate 65. Through holes 71 and 72 that are long in the vertical direction are formed in the support portion 70 at positions corresponding to the positioning pins 67 and at positions corresponding to the female screw portions 68, respectively. The through hole 71 is engaged with the positioning pin 67 of the support portion 66 on the light amount adjustment plate 60 side, and the screw 73 is screwed into the female screw portion 68 and tightened to tighten the light amount via the support portions 66 and 70. The plate 60 is fixed to the substrate mounting plate 65. As described above, since the support portion 66 on the light amount adjustment plate 60 side has long through holes 71 and 72, a plurality of screws can be moved by loosening the screws 73 and moving the support portion 66 in the vertical direction. The height of the light quantity adjustment plate 60 with respect to the LED element 11 can be adjusted (finely adjusted). That is, the first adjustment mechanism 74 is configured by the support portions 66 and 70, the positioning pin 67, the female screw portion 68, the through holes 71 and 72, and the like. The same first adjustment mechanism (not shown) as the first adjustment mechanism 74 is also provided on the rear end side of the light amount adjustment plate 60. Thus, by providing the first adjustment mechanism on the front end side and the rear end side of the light amount adjustment plate 60, the height of the light amount adjustment plate 60 with respect to the plurality of light sources 11 can be adjusted. In the state where the first adjustment mechanism 74 is fixed, the rear end side of the light amount adjustment plate 60 is moved up and down by the adjustment mechanism on the rear end side, whereby the light amount adjustment plate 60 for the plurality of light sources 11 (with respect to the substrate 12). It is also possible to adjust the inclination angle.

  Further, in the example shown in FIGS. 12A and 12B, the entire light source 10 is fixed to the light source mounting plate 75, and the light source 10 is moved to the moving frame 24 of the illumination optical moving frame unit 23 via the light source mounting plate 75. It is trying to be attached to. On the light source 10 side, as shown in (b), a circular through-hole 76 that is slightly larger than a screw 78 described later is formed. On the other hand, the light source mounting plate 75 is located at a position corresponding to the through-hole 76. A long through hole 77 is formed in the front-rear direction. In FIG. 12B, these through holes 76 and 77 are only at one place, but actually, they are formed at a plurality of places. The entire light source 10 is attached to the light source mounting plate 75 by passing screws 78 through these through holes 76 and 77 and screwing the screws 78 into female threaded portions (not shown) of the light source mounting plate 75. . As described above, since the through-hole 77 is formed long in the front-rear direction, the board mounting plate 75 can be moved in the front-rear direction without changing the position of the board 12 by loosening the screw 78. . As a result, the light quantity adjustment plate 60 can be moved in the front-rear direction with respect to the plurality of light sources 11 to finely adjust the relative positional relationship between the light source 11 and the element corresponding portion 62 a of the light quantity adjustment window 62. On the contrary, when the through hole 76 on the substrate 12 side is long in the front-rear direction and the through hole 77 on the light source mounting plate 65 side is formed in a circle, the substrate 12 is moved in the front-rear direction together with the plurality of light sources 11. Can be made. In any case, it is possible to change the relative position of the light amount adjustment plate 60 in the front-rear direction with respect to the plurality of light sources 11.

  In addition, a second adjustment mechanism 80 similar to the first adjustment mechanism 74 described above is provided between the front end side and the rear end side of the substrate mounting plate 65 and the moving frame 24. Thereby, height adjustment and inclination adjustment of the light source 10 can be performed with respect to the moving frame 24.

  As described above, the first adjustment mechanism 74 and the second adjustment mechanism 80 are provided, and the position and inclination of the light amount adjustment plate 60 in the front-rear direction with respect to the light source 11 and further the inclination of the entire light source 10 with respect to the moving frame 24 are finely adjusted. By adjusting, it is possible to further suppress unevenness in the amount of light in the reading line L.

  Further, instead of the through hole 71 shown in FIGS. 12A and 12B, a through hole (not shown) having a diameter slightly larger than that of the positioning pin 67 is formed. When an arc-shaped through hole (not shown) is formed with the through hole as a center, the light amount adjusting plate 60 is swung (rotated) in the left-right direction around the positioning pin 67 with respect to the plurality of light sources 11. Can be made. That is, it is possible to reduce the amount of light passing through the light amount adjustment window 62 (see FIG. 10) by tilting the light amount adjustment plate 60 with respect to the plurality of light sources 11. This also makes it possible to suppress unevenness in the amount of light.

  In the above description, the case where the light source of the present invention is used in an image reading apparatus or an image forming apparatus has been described as an example. However, the light source according to the present invention is not limited to this, and light intensity unevenness is eliminated in an illumination device such as a display. It can be applied to such cases.

FIG. 2 is a diagram schematically illustrating a vertical cross section of the image forming apparatus as viewed from the front side (front side). It is the figure which looked at the longitudinal section of the image reading device from the front side (front side), and is a figure explaining an optical system. It is the figure which looked at the longitudinal section of the image reading device from the front side (front side), and is a figure explaining a drive system. FIG. 4 is a top view for explaining the relationship between the light source 10, the size of the document, and the position of the document at the time of image reading, and is a diagram for explaining the case where the document size is A row and B row. It is a top view explaining the relationship between the light source 10, the size of an original, and the position of the original at the time of image reading, and is a figure explaining the case where an original size is an inch size. It is a figure which shows typically the longitudinal section of an image reading device seeing from the front side (front side). It is a figure explaining how to irradiate the irradiation angle (alpha) of a LED element, and a reading line. It is a figure explaining the light quantity nonuniformity which generate | occur | produces along the main scanning direction (array direction of an LED element). It is an enlarged view near the light source. It is the figure which looked at the light source in FIG. 9 from the reading line side. It is a figure explaining how light quantity unevenness in the main scanning direction is suppressed by providing a light quantity adjusting plate. (A) is the figure which looked at the 1st adjustment mechanism and the 2nd adjustment mechanism from the front side, and (b) is the figure seen similarly from the right side.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Sheet feeding part, 3 ... Image forming part, 4 ... Fixing part, 5 ... Sheet discharge part, 6 ... Image reading part, 7 ... Image reading apparatus, 10 ...... Light source, 11, L1 to L22 ... LED element (light source element), 12 ... substrate, 13 ... imaging lens, 14 ... CCD (individual imaging element), 24 ... moving frame, 60 ... light quantity Adjustment plate (light quantity adjustment member), 60a... Surface facing the image surface in the light quantity adjustment plate, 60b... Surface facing the LED element in the light quantity adjustment plate, 62. 62b: Inter-element corresponding portion, 62c: Periphery of light quantity adjustment window, 74: First adjusting mechanism, 80: Second adjusting mechanism, a: Window width of corresponding element, b: Between elements Corresponding window width, L ... reading line, P ... sheet

Claims (10)

In a line-shaped light source that irradiates the image surface of a document in the main scanning direction,
A plurality of light source elements aligned in the main scanning direction;
Holding the plurality of light source elements in an aligned state and supplying power to the plurality of light source elements;
A light amount adjusting member disposed along the main scanning direction disposed between the plurality of light source elements and the image plane; and a light amount adjusting member long in the main scanning direction,
The light amount adjustment member has a light amount adjustment window that is long in the main scanning direction through which light emitted from the plurality of light source elements and directed toward the image plane passes.
In the light amount adjustment window, the window width of the corresponding part between the elements corresponding to the middle of the two light source elements adjacent to each other is set larger than the window width of the corresponding part of the element corresponding to the light source element.
A light source characterized by that. In the light amount adjustment window, the window width gradually decreases from the element corresponding part toward the element corresponding part.
The light source according to claim 1. In the periphery of the light amount adjustment window, the periphery located between the element corresponding part and the inter-element corresponding part is formed in a straight line,
The light source according to claim 2. A portion of the peripheral edge of the light amount adjustment window located in the vicinity of the corresponding portion of the element is formed with a gentle curve that is convex inward, and a portion of the peripheral portion of the light adjustment window is positioned inward. Formed with a gentle concave curve,
The light source according to claim 2. A first adjustment mechanism for adjusting the position of the light amount adjustment member with respect to the substrate;
The light source according to claim 1, wherein the light source is a light source. In the light amount adjusting member, a surface facing the image surface around the light amount adjusting window is formed with a low reflectance.
The light source according to claim 1, wherein the light source is a light source. In the light amount adjusting member, a surface facing the light source element around the light amount adjusting window is formed with a low reflectance.
The light source according to claim 1, wherein the light source is a light source. The image surface of the document is main-scanned with a long line-shaped light source, and the light source or the document is moved in the direction orthogonal to the main-scanning direction to perform sub-scanning. In the image reading apparatus that guides the reflected light reflected by the light to the fixed image sensor through the imaging lens,
The light source is the light source according to any one of claims 1 to 7.
An image reading apparatus. A moving frame that supports the light source and moves in the sub-scanning direction;
A second adjustment mechanism that adjusts an inclination of the light source with respect to the moving frame;
The image reading apparatus according to claim 8. An image reading unit that reads an image of an original, an image forming unit that forms an image on a sheet based on image information of the original read by the image reading unit, and a sheet feeding unit that supplies the sheet to the image forming unit In an image forming apparatus comprising:
The image reading device according to claim 8 or 9 is disposed in the image reading unit.
An image forming apparatus.

Images