JP5716847B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus.

  2. Description of the Related Art Conventionally, there is an image reading apparatus that irradiates a reading document with light emitted from a light source and forms an image on a photoelectric conversion element using light reflected from the reading document with an imaging lens (for example, Patent Document 1, 2).

  In the image reading apparatus of Patent Document 1, a light shielding plate is disposed opposite to a reading document, and the reflectance of the light source side surface of the light shielding plate is set higher than the reflectance of the surface of the reading document side. The side of the scanned document is painted black.

  The image reading apparatus of Patent Document 2 uses a black steel plate as a base member to which an exposure lamp as a light source is attached.

JP 2002-247297 A JP 2006-189537 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus and an image forming apparatus that can reduce the amount of light that is reflected from the surface to be read and irradiated again onto the surface to be read.

An image reading apparatus according to a first aspect of the present invention includes a light source that emits light, an incident surface on which light emitted from the light source is incident, an exit surface that emits light toward the surface to be read, and the incident A light guide having a side surface that reflects light incident from a surface and guides the light to the emission surface and transmits reflected light from the read surface; and a part of the light emitted from the emission surface, a reflecting member for reflecting the surface to be read, said receiving reflected light from the reading surface, the image reading apparatus having a reading means for reading an image of the surface to be read, the side, the object An upper side surface of the reading surface side and a lower side surface facing the upper side surface are provided, and light incident on the upper side surface is transmitted to the lower side surface, and the light guide is a part of the upper side surface. Is reflected from the surface to be read with respect to the upper member disposed above the light guide. Projecting to the optical axis side of the optical path that guides the light to the reading means, and the upper member is directed from the reflecting member to the surface to be read, and the regular reflection component of the light reflected from the surface to be read is transmitted to the light guide. Light guide means arranged at an angle leading to the upper side surface.

  In the image reading apparatus according to claim 2 of the present invention, the surface roughness of the side surface of the light guide is 0.1 μm or less as measured by the arithmetic average roughness Ra of JIS-B-0601. .

An image forming apparatus according to a third aspect of the present invention forms an image based on the image reading apparatus according to the first or second aspect and image information read by the reading unit of the image reading apparatus. And an image forming unit.

  The image reading apparatus according to the first aspect includes a plurality of light sources arranged in a row and emitting light, and guides the light emitted from the plurality of light sources to a surface to be read and reflects light from the surface to be read. A light guide disposed so as to transmit, a light guide provided on an upper member disposed above the light guide, and guiding reflected light from the surface to be read to the light guide; Reading means for receiving reflected light from the reading surface and reading an image on the surface to be read.

  In the image reading apparatus according to the second aspect, at least a part of the light guide from the light incident surface to the light exit surface reflects the reflected light from the read surface to the reading unit with respect to the upper member. It protrudes to the optical axis side of the optical path to guide.

  In the image reading apparatus according to the third aspect, the horizontal distance from the optical axis to the end of the upper member on the optical axis side is set to 12 mm or more.

  In the image reading device according to the fourth aspect, the light guide is transparent.

  An image forming apparatus according to a fifth aspect provides an image based on information on an image read by the image reading apparatus according to any one of the first to fourth aspects and the reading unit of the image reading apparatus. An image forming unit to be formed.

  According to the first aspect of the present invention, compared to the case where the reflected light from the surface to be read does not pass through the inside of the light guide, the amount of light that is reflected again from the surface to be read is applied to the surface to be read is reduced. be able to.

  According to the second aspect of the present invention, the surface to be read is compared with the case where the surface roughness of the side surface of the light guide is larger than 0.1 μm in the surface roughness measured by the arithmetic average roughness Ra of JIS-B-0601. The amount of light that is reflected on the surface to be read again can be reduced.

According to the third aspect of the present invention, it is possible to suppress a decrease in the luminance difference of the image as compared with the case where the reading unit that does not transmit the reflected light from the surface to be read through the inside of the light guide is used.

  According to the configuration of the first aspect, compared to the case where the reflected light from the read surface does not pass through the inside of the light guide, the amount of light that is reflected on the read surface again by the reflected light from the read surface is reduced. Can be reduced.

  According to the structure of the 2nd aspect, the light quantity of the reflected light which reaches | attains an upper member from a to-be-read surface can be reduced compared with what the part between an entrance plane and an output surface is covered with an upper member.

  According to the configuration of the third aspect, the reflected light that reaches the upper member from the surface to be read is compared with the case where the upper member is provided adjacent to the optical axis of the optical path that guides the reflected light from the surface to be read to the reading means. The amount of light can be reduced.

  According to the structure of the 4th aspect, compared with the case where the light guide which cannot visually recognize an inside from the to-be-read surface side is used, reduction of the total reflection efficiency of the light inside a light guide can be suppressed.

  According to the structure of the 5th aspect, compared with the case where the reading means from which the reflected light from a to-be-read surface does not permeate | transmit the inside of a light guide is used, the fall of the brightness | luminance difference of an image can be suppressed.

1 is an overall view of an image forming apparatus according to an embodiment of the present invention. 1 is a configuration diagram of an image forming unit according to an embodiment of the present invention. FIG. 1 is a configuration diagram of an automatic document feeder and a document reading device according to an embodiment of the present invention. FIG. 1 is a perspective view of a main part of a document reading apparatus according to an embodiment of the present invention. 1 is a perspective view of the inside of a main part of a document reading apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view in the sub-scanning direction of the main part of the document reading apparatus according to the embodiment of the present invention. (A) It is a fragmentary sectional view of the principal part of the original reading apparatus concerning embodiment of this invention. (B) It is a schematic diagram which shows the permeation | transmission state of the light in the light guide member which concerns on embodiment of this invention. 6 is a cross-sectional view of the main part of the document reading apparatus according to the embodiment of the present invention in the sub-scanning direction and a graph showing the relative intensity distribution of light at the reading position. (A) It is a schematic diagram which shows the advancing state of the light in the principal part of the original reading apparatus of a 1st comparative example. (B) It is a schematic diagram which shows the advancing state of the light in the principal part of the original document reading apparatus concerning embodiment of this invention. (A) It is a schematic diagram which shows the advancing state of the light in the principal part of the original reading apparatus of a 2nd comparative example. (B) It is a schematic diagram which shows the advancing state of the light in the principal part of the original document reading apparatus concerning embodiment of this invention. It is a fragmentary sectional view of the principal part of the original reading apparatus which concerns on the other Example of embodiment of this invention.

  An example of an image reading apparatus and an image forming apparatus according to an embodiment of the present invention will be described.

(overall structure)
As shown in FIG. 1, an automatic document feeder 12 that automatically feeds a plurality of read documents G one by one, and one reading, are arranged on the upper portion of the apparatus main body 10 </ b> A of the image forming apparatus 10 according to the present embodiment. As an example of a platen glass 43 on which a document G is placed, and an image reading device that reads a read surface GA (see FIGS. 6 and 7) of a read document G that is transported by the automatic document feeder 12 or placed on the platen glass 43. A document reading device 14 is provided. In addition, a control unit 71 that controls the operation of each unit of the image forming apparatus 10 is provided at the center of the apparatus main body 10A. Note that an arrow UP shown in the drawing indicates a vertically upward direction, and an arrow H indicates a horizontal direction.

  A plurality of image forming units 30 that form toner images of different colors are provided at the center in the vertical direction of the apparatus main body 10A. Further, on the upper side of the image forming unit 30, an endless intermediate transfer belt 32 to which the toner image formed by the image forming unit 30 of each color is transferred while being circulated in the direction of arrow A in the drawing is provided. The image forming unit 30 corresponds to an example of an image forming unit.

  As the image forming unit 30, four image forming units 30Y, 30M, 30C, and 30K are provided corresponding to the toner colors of yellow (Y), magenta (M), cyan (C), and black (K). First, the position of the image forming unit 30Y on which the yellow (Y) toner image transferred to the intermediate transfer belt 32 is formed is high, and the black (K) toner image transferred to the intermediate transfer belt 32 is finally formed. The image forming units 30Y, 30M, 30C, and 30K are arranged in an inclined state with respect to the horizontal direction (the direction indicated by the arrow H) so that the position of the image forming unit 30K to be lowered.

  These four image forming units 30Y, 30M, 30C, and 30K are basically composed of the same members. In the following description, characters (Y, M, C, K) corresponding to each color are added to the code when distinguishing each color, and characters corresponding to each color are omitted unless otherwise distinguished.

  As shown in FIG. 2, the image forming unit 30 for each color is provided with an image carrier 34 that is rotated by a driving means (not shown), and charging for primary charging that charges the surface of the image carrier 34. A member 36 is provided.

  Further, on the downstream side in the rotation direction of the image carrier 34 with respect to the charging member 36, the surface of the image carrier 34 whose surface is charged by the charging member 36 is exposed to light corresponding to each color to form an electrostatic latent image. An exposure device 40 is provided, and the electrostatic latent image formed on the surface of the image carrier 34 is developed with toner of each color on the downstream side of the rotation direction of the image carrier 34 with respect to the exposure device 40. A developing device 42 that visualizes the toner image is provided.

  As shown in FIG. 1, the toner of each color is supplied to the developing unit 42 of each color of yellow (Y), magenta (M), cyan (C), and black (K) above the intermediate transfer belt 32. Toner cartridges 38Y, 38M, 38C, and 38K are provided. The toner cartridge 38K containing black (K) toner is larger in size than the other color toner cartridges 38Y, 38M, and 38C in accordance with the frequency of use.

  On the other hand, as shown in FIG. 2, the primary transfer for transferring the toner image formed on the surface of the image carrier 34 to the intermediate transfer belt 32 on the opposite side of the image carrier 34 across the intermediate transfer belt 32. A member 46 is provided. Further, a cleaning device 44 that cleans residual toner or the like remaining on the surface of the image carrier 34 without being transferred from the image carrier 34 to the intermediate transfer belt 32 is in contact with the surface of the image carrier 34, and is in contact with the primary transfer member 46. The image holding member 34 is provided on the downstream side in the rotation direction.

  With this configuration, the exposure device 40 (Y provided individually in the image forming unit 30 (Y, M, C, K) for each color of yellow (Y), magenta (M), cyan (C), and black (K). , M, C, K), the image data of each color is sequentially output. Further, the light emitted according to the image data from these exposure devices 40 (Y, M, C, K) exposes the surface of the corresponding image carrier 34, and the surface of the image carrier 34 is electrostatically exposed. A latent image is formed. The electrostatic latent image formed on the surface of the image carrier 34 is yellow (Y), magenta (M), cyan (C), and black (K) by the developing units 42 (Y, M, C, and K), respectively. Are developed as toner images of respective colors.

  Further, yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the surface of the image carrier 34 are converted into image forming units 30 (Y, M, C, K) are transferred onto the intermediate transfer belt 32 inclined at an upper position by the primary transfer member 46.

  Here, as shown in FIG. 1, the intermediate transfer belt 32 includes a drive roll 48 that applies a driving force to the intermediate transfer belt 32, a support roll 50 that rotates and supports the intermediate transfer belt 32 from the back surface, and an intermediate transfer. A tension applying roll 54 for applying tension to the belt 32, a first driven roll 56, and a second driven roll 58 are wound around at a predetermined tension.

  Further, a cleaning device 52 for cleaning the surface of the intermediate transfer belt 32 is provided on the opposite side of the drive roll 48 across the intermediate transfer belt 32. This cleaning device 52 is provided on the front side of the apparatus main body 10A (a user stands up). By opening a front cover (not shown) provided on the front side, the apparatus main body 10A is detachable.

  In addition, a toner image primarily transferred onto the intermediate transfer belt 32 is disposed at the lower end of the intermediate transfer belt 32 disposed at a predetermined angle with respect to the horizontal direction (arrow H direction). A secondary transfer member 60 for secondary transfer of the toner image to a recording sheet P as a recording medium is disposed so as to sandwich the intermediate transfer belt 32 with the support roll 50. That is, the position sandwiched between the secondary transfer member 60 and the support roll 50 is the secondary transfer position at which the toner image is transferred to the recording sheet P.

  Above the support roll 50 and the secondary transfer member 60, a fixing device 64 for fixing the toner image to the recording sheet P transferred by the secondary transfer member 60 and transported along the transport path 62 is provided. It has been. The fixing device 64 includes a heating roll disposed on the image surface side of the recording sheet P and a pressure roll that pressurizes the recording sheet P toward the heating roll.

  Further, on the downstream side in the conveyance direction of the recording sheet P with respect to the fixing device 64 (hereinafter simply referred to as “the downstream side in the conveyance direction”), a conveyance roll 66 that conveys the recording sheet P on which the toner image is fixed is provided. A switching gate 68 for switching the conveyance direction of the recording sheet P is provided on the downstream side in the conveyance direction of the roll 66. A first discharge roll 70 that discharges the recording sheet P guided by the switching gate 68 switched in one direction to the first discharge unit 69 is provided on the downstream side in the conveyance direction of the switching gate 68.

  Further, on the downstream side in the transport direction of the switching gate 68, a second discharge roll 74 that discharges the recording sheet P guided by the switching gate 68 switched in the other direction and transported by the transport roll 73 to the second discharge section 72. And a third discharge roll 78 for discharging the recording sheet P to the third discharge portion 76 is provided.

  On the other hand, on the upstream side in the conveyance direction of the recording sheet P with respect to the secondary transfer member 60 (hereinafter, simply referred to as “upstream side in the conveyance direction”), the paper feeding units 80, 82, 84, 86 in which the recording sheet P is accommodated. Are provided, and recording sheets P of different sizes are accommodated in the paper feeding sections 80, 82, 84, and 86, respectively.

  Further, each of the paper feeding units 80, 82, 84, 86 is provided with a paper feeding roll 88 that takes the stored recording sheet P from the paper feeding units 80, 82, 84, 86 to the transport path 62. On the downstream side of the roll 88 in the conveyance direction, a conveyance roll 90 and a conveyance roll 92 that convey the recording sheets P one by one are provided. In addition, a position adjustment roll 94 that stops the recording sheet P at one end and sends it to the secondary transfer position at a predetermined timing is provided on the downstream side of the conveyance roll 92 in the conveyance direction.

  On the other hand, in order to form an image on both sides of the recording sheet P, a duplex conveying unit 98 that reverses and conveys the recording sheet P is provided on the side of the secondary transfer position. A reversing path 100 through which the recording sheet P conveyed by reversing the conveying roll 73 is fed is provided. A plurality of conveying rolls 102 are provided along the reversing path 100, and the recording sheet P conveyed by these conveying rolls 102 is conveyed again to the position adjusting roll 94 with the front and back reversed. It has become.

  Further, a foldable manual sheet feeding unit 106 is provided next to the duplex conveying unit 98. A paper feed roll 108 and transport rolls 110 and 112 for transporting the recording sheet P fed from the opened foldable manual sheet feeding unit 106 are provided and transported by the transport rolls 110 and 112. The recording sheet P is conveyed to the position adjustment roll 94.

  Next, the configuration of the automatic document feeder 12 will be described.

  As shown in FIG. 3, the automatic document feeder 12 includes a document table 13 on which a plurality of read documents G are stacked, a sending roll 15 for feeding the read documents G one by one from the document table 13, and a sending roll. And a first transporting roll 17 that transports the read original G sent out by 15 further downstream.

  The automatic document feeder 12 has a first conveyance path 19 through which the read document G sent from the document table 13 is first conveyed. The first conveyance path 19 includes a second conveyance roll 21 that conveys the read original G separated one by one to a downstream roll, and a second conveyance roll 21 that conveys the read original G to a further downstream roll and forms a loop. 3 transport roll 23, position adjustment roll 25 for supplying read original G while adjusting the leading edge position of read original G with respect to the original reading apparatus 14 after resuming rotation after stopping once, and during reading An auxiliary roll 27 for assisting the conveyance of the read original G and a fourth conveyance roll 29 for conveying the read original G further downstream are provided. The first conveyance path 19 is provided with a guide member for guiding the read original G to be conveyed, but is not illustrated.

  A second transport path 31 is provided on the downstream side of the fourth transport roll 29, and on the downstream side of the second transport path 31, a discharge roll 35 that discharges the read original G that has been read to the discharge unit 33. Is provided.

  On the other hand, a third conveyance path 37 for reversing the read original G that has passed through the second conveyance path 31 is formed from the downstream side of the second conveyance path 31 toward the third conveyance roll 23. A switching gate 39 that switches the transport path of the read document G to the second transport path 31 or the third transport path 37 is provided at a branch position between the second transport path 31 and the third transport path 37.

  Here, the sending roll 15 is raised or lowered by a driving unit including a motor (not shown), and is raised and held at the retracted position while the image forming apparatus 10 is on standby. During the conveyance, the lowermost document G is lowered to convey the uppermost read original G on the original table 13. The delivery roll 15 and the first transport roll 17 are rotated by the connection of a clutch mechanism (not shown) to transport the read original G.

  The first transport roll 17, the second transport roll 21, and the third transport roll 23 form a loop by abutting the leading end of the read original G against the stopped position adjustment roll 25. The position adjustment roll 25 adjusts the position of the leading edge of the read document G that is bitten by the position adjustment roll 25 during loop formation. By forming the loop of the read original G, the read timing is adjusted, and the deviation (skew) of the read original G during reading is suppressed. Then, when the position adjustment roll 25 that has been stopped starts rotating in accordance with the start timing of reading, reading of the read original G is started.

  The switching gate 39 is switched so that the end portion is arranged on the upper side when reading one side of the read original G is started, and the read original G that has passed through the fourth transport roll 29 is discharged to the discharge portion 33. On the other hand, when the switching gate 39 sequentially reads both sides of the read original G, the end of the switching gate 39 is lowered so as to guide the read original G to the third conveyance path 37 in order to reverse the read original G. As a result, the read original G is guided again to the first conveyance path 19 via the third conveyance path 37.

  Next, the configuration of the document reading device 14 will be described.

  In the document reading device 14, a platen glass 43 is attached to an upper portion of a housing 41 provided at a lower portion of the automatic document feeder 12. The platen glass 43 includes a first platen glass 43A on which the read original G is placed in a stationary state, and a second platen glass 43B that forms a light transmitting portion for reading the read original G being conveyed. .

  In addition, the document reading device 14 emits light for reading an image on a surface to be read GA (see FIG. 6) of the read document G, and light to be read from the light emitting element 61 is read. The first carriage 18 to which the light guide member 65 that leads to the GA, the first mirror 75 that reflects the light emitted from the light guide member 65 and reflected by the read surface GA, and the first carriage 18 of the first carriage 18 are attached. A second carriage 45 to which a second mirror 45A and a third mirror 45B for guiding the light incident from one mirror 75 to the imaging unit 20 are attached. The imaging unit 20 corresponds to an example of a reading unit.

  The first carriage 18 stops under the second platen glass 43B (below the conveyance surface of the read original G), which is the initial position, or the read surface GA of the read original G over the entire first platen glass 43A. While moving along (see FIG. 7), the light L is emitted to the read original G by the light emission of the light emitting element 61, and the light L reflected by the read original G is guided to the second carriage 22. The detailed configuration of the first carriage 18 will be described later.

  The second carriage 22 reflects the light L incident from the first mirror 75 of the first carriage 18 downward, and the third mirror 45A returns the light L reflected by the second mirror 45A in the direction of the arrow X. And a mirror 45B.

  The imaging unit 20 includes an imaging lens 24 that images the light L (optical image) folded by the third mirror 45B, and a photoelectric conversion element that photoelectrically converts the optical image formed by the imaging lens 24. The electric signal (image signal) converted by the photoelectric conversion element 26 is sent to an image processing device 28 that is electrically connected to the photoelectric conversion element 26. In the image processing device 28, the electrical signal is subjected to image processing, and the image signal subjected to the image processing is sent to the exposure device 40 (see FIG. 2) by the control unit 71 (see FIG. 1).

  Here, first, when reading the image of the read original G placed on the first platen glass 43A, the first carriage 18 and the second carriage 22 move in the moving direction (arrow X) at a moving distance ratio of 2: 1. Direction). At this time, the light L is irradiated from the light emitting element 61 of the first carriage 18 to the read surface GA (see FIG. 7) of the read original G, and the light L reflected by the read surface GA is applied to the second carriage 22. The light L is reflected in the order of the second mirror 45A and the third mirror 45B and guided to the imaging lens 24. The light L guided to the imaging lens 24 is imaged on the light receiving surface of the photoelectric conversion element 26. Note that since the moving distance of the second carriage 22 is half the moving distance of the first carriage 18, the optical path length of the light L from the read surface GA of the read original G to the photoelectric conversion element 26 does not change.

  The photoelectric conversion element 26 is a one-dimensional sensor and processes one line of the read original G in a direction crossing the moving direction (arrow X direction). In the document reading device 14, after the reading of one line in the direction intersecting the moving direction is completed, the first carriage 18 is moved in the moving direction to read the next line of the read document G. By executing this over the entire read original G, reading of one page is completed. In the following description, the moving direction of the first carriage 18 and the second carriage 22 is referred to as the sub-scanning direction, and the direction intersecting the moving direction is referred to as the main scanning direction.

  On the other hand, when the image of the read original G is read on the second platen glass 43B, the read original G conveyed by the automatic original conveying device 12 passes over the second platen glass 43B. At this time, the first carriage 18 and the second carriage 22 are stopped at the solid line reading position shown at one end (left end in FIG. 3) of the document reading device 14. At this reading position, first, the light L reflected by the first line of the read original G that has been conveyed is imaged by the imaging lens 24, and the image is read by the photoelectric conversion element 26. That is, after one line in the main scanning direction is processed by the photoelectric conversion element 26 which is a one-dimensional sensor, one line in the next main scanning direction of the read original G to be conveyed is read. Then, when the rear end of the read original G passes through the reading position of the second platen glass 43B, the reading of one page of the read original G is completed in the sub-scanning direction.

(Main part configuration)
Next, the configuration of the first carriage 18 will be described.

  As shown in FIG. 4, the first carriage 18 is sub-scanned with the main scanning direction as a longitudinal direction on top of two side plates 55A and 55B arranged to face each other with a gap in the main scanning direction (arrow Y direction). Both ends of the first holder 51 and the second holder 53, which are sheet metals arranged at intervals in the direction (arrow X direction), are attached. A third holder 47 and a fourth holder 49 are attached to the side plates 55A and 55B. Here, the first holder 51 corresponds to an example of an upper member.

  The upper surfaces of the first holder 51 and the second holder 53 form the upper surface of the first carriage 18 and are arranged to face the surface to be read GA (see FIG. 6) of the read original G. The arrangement interval between the side plates 55A and 55B in the main scanning direction is larger than the width of the image forming area in the main scanning direction of the read document G (see FIG. 1).

  The first holder 51 has an L-shaped cross section in the sub-scanning direction, and includes an upper wall 51A as an upper surface of the first carriage 18 and a side wall 51B in front of the first carriage 18 in the sub-scanning direction (movement direction). It consists of The end portion of the upper wall 51A is bent downward. In addition, one flat portion 57A of a bracket 57 having a main scanning direction as a longitudinal direction and a cross-section in the sub-scanning direction having a reverse letter shape is fixed by a screw 77 inside the first holder 51 and below the side wall 51B. .

  As shown in FIG. 5, in the other inclined plane portion 57B of the bracket 57, a light emitting element 61 as an example of a light source is provided along a main scanning direction on a circuit board 59A having a main scanning direction as a longitudinal direction. A plurality of light emitting portions 59 arranged in a row are attached. The circuit board 59A is supplied with power from the control unit 71 (see FIG. 1) via the flexible board 63 connected to the end. In the present embodiment, an LED (Light Emitting Diode) element is used as the light emitting element 61.

  Here, the control unit 71 (see FIG. 1) of the image forming apparatus 10 incorporates a light source driving circuit (not shown) for driving the light emitting unit 59. The light source driving circuit includes a resistor that adjusts the amount of light emitted from each light emitting element 61 to the read original G (see FIG. 1). The light source driving circuit drives the light emitting unit 59 based on a light source driving signal for controlling on / off of light emission of the light emitting element 61 and an adjustment signal for adjusting the amount of light. .

  As shown in FIG. 6, each light emitting element 61 is inclined with respect to the read surface GA of the read original G at a predetermined angle. As a result, the light emitted from the light emitting element 61 toward the read original G enters the read face GA of the read original G from a predetermined inclination direction and is scattered. Compared with the case where light is incident on the reading surface GA perpendicularly, regular reflection on the background (white) of the read original G is suppressed, and a decrease in image luminance difference (contrast) is suppressed.

  In the first carriage 18, a light guide member 65 corresponding to an example of a light guide having a main scanning direction as a longitudinal direction is disposed facing the light emitting surface of each light emitting element 61. As an example, the light guide member 65 is formed by forming an acrylic resin into a rectangular parallelepiped shape, and both end portions in the main scanning direction are supported by the side plates 55A and 55B. The light guide member 65 diffuses directional light at least in the main scanning direction and guides the light emitted from the light emitting element 61 to a position near the reading position of the read original G (see FIG. 1). Yes.

  Thereby, light from the light emitting element 61 of the light emitting portion 59 is totally reflected and emitted on the light emitting surface 65A opposite to the surface facing the light emitting element 61 of the light guide member 65. The variation in the light amount distribution on the light exit surface 65A is suppressed. Other materials for the light guide member 65 include polycarbonate resin, polyimide resin, and glass.

  A light diffusing plate 67 is joined to the light emitting surface 65 </ b> A of the light guide member 65. The diffusion plate 67 is made of an acrylic resin as an example, and unevenness (not shown) for diffusing the light incident from the light emission surface 65 </ b> A of the light guide member 65 is formed on the light emission surface of the diffusion plate 67. ing. By changing the shape of the uneven pattern, the light emitted from the diffusion plate 67 is shaped into a circle or an ellipse. Other materials for the diffusion plate 67 include polycarbonate resin, polyester resin, and glass.

  On the other hand, at a position separated from the diffusion plate 67 by a predetermined distance in the sub-scanning direction, a reflection plate that reflects the light emitted from the diffusion plate 67 and guides it to the reading position (read surface GA) of the read document G. 79 is arranged. The reflection plate 79 is a mirror body whose longitudinal direction is the main scanning direction, and the surface opposite to the light reflection surface is fixed to the inclined surface of the second holder 53.

  Further, below the light guide member 65 and the diffusing plate 67, a first mirror 75 that guides the light reflected by the read original G to the second mirror 45A (see FIG. 3) of the second carriage 22 is provided. Yes. Both ends of the first mirror 75 are held by holes formed in the side plates 55A and 55B (see FIG. 4).

  In the first carriage 18, the light L emitted from each light emitting element 61 proceeds while being totally reflected inside the light guide member 65 and is diffused by the diffusion plate 67. Here, if the optical axis of the light L reflected from the read surface GA of the read original G and traveling toward the first mirror 75 is an optical axis LT, a part of the light L diffused by the diffusion plate 67 is the second platen glass. The read original G is irradiated from one side of the optical axis LT through 43B, and the rest of the light L is reflected by the reflector 79 and then passes through the second platen glass 43B from the other side of the optical axis LT. Is irradiated. Then, the light L irradiated to the read original G is reflected by the first mirror 75 after being reflected by the read surface GA of the read original G and, as shown in FIG. An image is formed by the photoelectric conversion element 26 through the lens 24, and image information is read. In FIG. 6, the optical axis LT corresponds to an example of the optical axis of the optical path that guides the reflected light from the read surface GA of the read original G to the imaging unit 20.

  Next, details of the light guide member 65 will be described. In FIG. 7 and subsequent figures, description will be made with reference to partial views in which illustration of the bracket 57 and the side plate 55A is omitted.

  As shown in FIG. 7B, the light guide member 65 includes a light incident surface 65B on which the light L from the light emitting element 61 (see FIG. 7A) is incident, and a light emitting surface 65A on which the light L is emitted. And an upper side surface 65C located above the reading document G (see FIG. 7A) and a lower side surface 65D facing the upper side surface 65C and positioned below the upper side surface 65C. ing. The upper side surface 65C and the lower side surface 65D have surface roughness set in advance so that the light L is totally reflected, and the entire light guide member 65 is colorless and transparent.

  Here, in this embodiment, the light transmittance measured by the test method (part 1: single beam method) of the total light transmittance of the plastic-transparent material of JIS-K-7361-1: 1997 is 80%. The above is defined as a transparent member. The light guide member 65 is preferably a transparent member, but may have a light transmittance of 80% or less.

  The surface roughness of the upper side surface 65C and the lower side surface 65D of the light guide member 65 is, for example, such that the surface roughness measured by the arithmetic average roughness Ra of JIS-B-0601 is 0.1 μm or less. It is desirable to set. In terms of suppressing re-reflection of the light L from the upper side surface 65C of the light guide member 65 to the read original G, the surface roughness of the upper side surface 65C is made rougher than 0.1 μm, and the light L incident from the outside is scattered. However, in this case, since the total reflection inside the light guide member 65 is affected, it is necessary to set an upper limit of the surface roughness. As a method for finishing the light guide member 65 to a surface roughness of Ra 0.1 μm or less, for example, injection molding may be used.

  Here, since the light guide member 65 is transparent, as shown in FIG. 7B, in the light guide member 65, the light LC incident on the upper side surface 65C at an incident angle α (an angle smaller than the critical angle) is obtained. Then, the light is refracted at the refraction angle β on the upper side surface 65C, passes through the light guide member 65, is refracted again on the lower side surface 65D, and proceeds downward from the lower side surface 65D.

  On the other hand, as shown in FIG. 7A, the light guide member 65 includes a first holder 51 (a part of the upper side surface 65C from the light incident surface 65B to the light output surface 65A above the light guide member 65). It protrudes toward the optical axis LT with respect to the upper wall 51A), and is arranged so that reflected light from the surface GA to be read enters and is transmitted. The light guide member 65 does not have to protrude entirely toward the optical axis LT with respect to the first holder 51, and at least the light incident surface so that the reflected light from the surface GA to be read is incident and transmitted. A part of the upper side surface 65 </ b> C from 65 </ b> B to the light emitting surface 65 </ b> A only has to protrude from the end 51 </ b> C of the first holder 51.

  Next, the position of the end 51C of the first holder 51 will be described.

  FIG. 8 is a cross-sectional view of the first carriage 18 in the sub-scanning direction and the light L (including LA and LB) applied to the read surface GA of the read original G around the reading position X0 of the read original G. A graph showing the result of calculating the change in relative intensity in the sub-scanning direction by simulation is shown.

  In the graph of the intensity distribution of the light L in the sub-scanning direction, the reading position X0 is the intensity distribution center, and the relative intensity decreases as the position moves away from the reading position X0 in the sub-scanning direction. Here, assuming that the relative intensity of the light L at the reading position X0 is 100%, the distance W1 from the reading position X0 to the position X3 where the relative intensity is 10% is calculated, and W1 = 12 mm. Further, when the distance W2 from the reading position X0 to the position X4 where the relative intensity is 7% was calculated, W2 = 15 mm.

  In the region where the relative intensity is 10% or more, the intensity of the light L reflected from the read original G is high. Therefore, if an upper member is provided in this region (region where the relative intensity is 10% or more), Light re-reflects on the upper surface of the upper member, and as described above, the luminance difference (contrast) of the image is reduced in the photoelectric conversion element 26 (see FIG. 1). For this reason, in the first carriage 18 of the present embodiment, the distance from the optical axis LT passing through the reading position X0 to the upper surface end of the first holder 51 (here, the horizontal distance d) is set to d = W1 = 12 mm. . Although the horizontal distance d is preferably 12 mm or more, it is preferable to set the horizontal distance d ≧ 15 mm so that the relative strength is 7% or less. The upper limit value of the horizontal distance d is determined based on the installation area of the first holder 51 in the first carriage 18.

  On the other hand, on the reflection plate 79 side from the reading position X0 in the sub-scanning direction, the reflection plate 79 is disposed closer to the optical axis LT than the end 51C of the first holder 51. The attachment position of the reflection plate 79 is as follows. Since the distance is set based on the reflection state of the light LB emitted from the diffusion plate 67, the distance from the optical axis LT to the reflection plate 79 may be within 12 mm.

  Next, the progress of the light L in the first carriage 18 will be described. Here, a case where the read original G is on the first platen glass 43A will be described.

  As shown in FIG. 7A, when the reading document G is placed on the first platen glass 43A and the reading operation is started, the first carriage 18 moves in the sub-scanning direction (arrow X direction) and emits light. The element 61 emits light. The light L emitted from the light emitting element 61 enters the light guide member 65 from the light incident surface 65B while spreading at a predetermined divergence angle. Since the light L travels at an angle larger than the critical angle inside the light guide member 65, the light L travels to the light exit surface 65A while being totally reflected by the upper side surface 65C and the lower side surface 65D.

  Subsequently, the light L emitted from the light emitting surface 65A of the light guide member 65 is diffused by the diffusing plate 67, and part of the light L travels toward the read original G as light LA, and the rest as the light LB. And is reflected by the reflector 79. The light LA and the light LB are incident on the first platen glass 43A and refracted, and are applied to the reading position X0 on the read surface GA of the read original G. The reading position X0 is the center position of the intensity distribution of the light L applied to the read original G and is on the optical axis LT.

  Subsequently, among the light L that has been reflected and diffused at the reading position X0 of the read original G, the light L that travels along the optical axis LT is directed from the surface of the read original G to the first mirror 75 to the first mirror 75. 75 is reflected. Then, as shown in FIG. 3, an image is formed by the photoelectric conversion element 26 from the second carriage 22 through the imaging lens 24.

  Next, the operation of this embodiment will be described.

  First, the difference between this embodiment and the first comparative example using the light guide member 202 that reflects the light L on the upper side surface 202A will be described.

  FIG. 9A shows a first carriage 200 that is a first comparative example with the first carriage 18 of the present embodiment. The first carriage 200 has a rectangular parallelepiped light guide member 202 that guides the light L emitted from the light emitting element 61 to the read original G. The first carriage 200 is obtained by replacing the light guide member 65 with the light guide member 202 in the first carriage 18 of the present embodiment. Therefore, the description is omitted. Further, in order to make the reflection path of the light L easy to understand, the optical path of the light L from the light emitting element 61 to the reading position X0 is not shown.

  Although the light guide member 202 totally reflects the light L inside, the upper side surface 202A located on the read original G side is rougher and more opaque than the surface of the light guide member 65 of this embodiment, and the upper side surface 202A The incident light L is reflected.

  Here, in the first carriage 200, the light L irradiated to the reading position X0 is reflected by the reading original G and becomes diffused light. Of the diffused light L, the light L traveling toward the first mirror 75 along the optical axis LT is reflected by the first mirror 75. The light LF emitted from the diffusing plate 67 and reflected by the reflecting plate 79 is applied to the read surface GA of the read document G and is reflected at a position shifted from the reading position X0 toward the reflecting plate 79 in the arrow X direction. It is reflected by X1 and becomes diffused light. Of the diffused light LF, the light directed toward the diffusion plate 67 is transmitted through the diffusion plate 67 and enters the light guide member 202, but is emitted outward from the end surface of the light guide member 202 on the light emitting element 61 side. Therefore, reading is not affected.

  On the other hand, a part of the light L emitted from the light guide member 202 and diffused by the diffusion plate 67 and directly directed to the read original G is the light guide member 202 side from the reading position X0 in the arrow X direction like the light LG. Toward the reflection position X2 shifted to, and is reflected at the reflection position X2 to become diffused light. Of the diffused light LG, the light LG directed toward the upper side surface 202A of the light guide member 202 is reflected by the upper side surface 202A because the upper side surface 202A is rough and opaque, and the read original G is read again. The surface GA is irradiated.

  The light LG irradiated again on the read original G fluctuates the intensity of the reflected light (diffused light) from the image on the read original G, and in particular, the background (white) of the read original G at the periphery of the blackened portion of the image. ) And the intensity of the reflected light from the image (black) are reduced. As a result, in the image photoelectrically converted by the photoelectric conversion element 26 (see FIG. 3), the brightness difference (contrast) between the background of the read original G and the image is lowered, and a phenomenon that the contour of the image is blurred occurs. .

  Next, as shown in FIG. 9B, the first carriage 18 of this embodiment will be described. In order to make the reflection path of the light L easy to understand, the optical path of the light L from the light emitting element 61 to the reading position X0 is not shown.

  In the first carriage 18, of the diffused light reflected by the read original G, the light L directed toward the first mirror 75 along the optical axis LT is reflected by the first mirror 75 as described above. The light LD emitted from the diffusing plate 67 and reflected by the reflecting plate 79 is applied to the surface GA to be read of the read document G, and reflected from the reading position X0 toward the reflecting plate 79 in the arrow X direction. It is reflected at the position X1 and becomes diffused light. Of the diffused light LD, the light LD directed toward the diffusion plate 67 is transmitted through the diffusion plate 67 and enters the light guide member 65, but is emitted outward from the light incident surface 65B. Does not affect.

  On the other hand, a part of the light L that is emitted from the light guide member 65 and is diffused by the diffusion plate 67 and goes directly to the read original G is light guide member 65 from the reading position X0 in the arrow X direction like the light LE. It is reflected at the reflection position X2 shifted to the side and becomes diffused light. Of the diffused light LE, the light LE toward the upper side surface 65C of the light guide member 65 is not reflected by the upper side surface 65C because the light guide member 65 is transparent, and is smaller than the critical angle at the upper side surface 65C. And is refracted and transmitted through the light guide member 65 and proceeds downward from the lower surface 65D. As a result, the light LE is prevented from being irradiated again on the surface GA to be read of the read original G, and fluctuations in the intensity of reflected light (diffused light) from the image on the read original G are reduced. And the fall of the brightness | luminance difference (contrast) in the image photoelectrically converted by the photoelectric conversion element 26 (refer FIG. 3) becomes small.

  Next, the difference between this embodiment and the second comparative example in which the light guide member 65 is used and the end portion 212A of the first holder 212 is closer to the optical axis LT than in this embodiment will be described.

  FIG. 10A shows a first carriage 210 that is a second comparative example with the first carriage 18 of the present embodiment. The same reference numerals are given to the same components as those of the first carriage 200 (see FIG. 9A), which is the first comparative example described above, and the description thereof is omitted. Further, in order to make the reflection path of the light L easy to understand, the optical path of the light L from the light emitting element 61 to the reading position X0 is not shown.

  The first carriage 210 has a light guide member 65 and has a configuration in which a first holder 212 is provided in place of the first holder 51 of the first carriage 200 (see FIG. 9A). The first holder 212 is made of a sheet metal whose longitudinal direction is the main scanning direction and whose width direction is the sub-scanning direction (arrow X direction), and whose cross section in the sub-scanning direction is L-shaped. Further, the upper surface of the first holder 212 forms the upper surface of the first carriage 210 and is disposed so as to face the read original G, and the end portion 212A of the upper surface is bent downward.

  In the first carriage 210, the horizontal distance d = W3 = 9 mm from the optical axis LT passing through the reading position X0 to the end 212A of the upper surface of the first holder 212. That is, the upper end 212A of the first holder 212 is closer to the reading position X0 than the upper end 51C of the first holder 51 of the present embodiment.

  Here, in the first carriage 210, the light L irradiated to the reading position X0 is reflected by the read original G and becomes diffused light. Of the diffused light L, the light L traveling toward the first mirror 75 along the optical axis LT is reflected by the first mirror 75.

  On the other hand, out of the light L emitted from the light guide member 65 and diffused by the diffusion plate 67 and directed directly to the read original G, it is emitted at a diffusion angle larger than the diffusion angle of the light LG (see FIG. 9A). The reflected light LH is reflected at the reflection position X5 that is shifted from the reflection position X2 (see FIG. 9A) in the direction of the arrow X to the side farther from the optical axis LT and becomes diffused light. The diffused light LH is reflected by the upper surface of the first holder 212 and re-irradiated to the read surface GA of the read original G because the first holder 212 is disposed close to the light guide member 65. become. Thereby, the difference between the intensity of the reflected light from the background (white) of the read original G and the intensity of the reflected light from the image (black) is reduced, and the luminance difference (contrast) between the background of the read original G and the image is reduced. A phenomenon occurs in which the image outline is blurred and the outline of the image is blurred.

  Next, as shown in FIG. 10B, the first carriage 18 of this embodiment will be described. In order to make the reflection path of the light L easy to understand, the optical path of the light L from the light emitting element 61 to the reading position X0 is not shown.

  In the first carriage 18, of the diffused light reflected by the read original G, the light L directed toward the first mirror 75 along the optical axis LT is reflected by the first mirror 75 as described above. Further, out of the light L emitted from the light guide member 65 and diffused by the diffusion plate 67 and directed directly to the read original G, it is emitted at a diffusion angle larger than the diffusion angle of the light LE (see FIG. 9B). The reflected light LK is reflected at the reflection position X5 that is shifted outward from the reflection position X2 (see FIG. 9B) in the direction of the arrow X, and becomes diffused light. Here, since the first holder 51 is not arranged in the range from the reading position X0 to the position X3 where the relative intensity of the light L is greater than 10%, the diffused light LK is not irradiated onto the first holder 51. Then, the light enters the upper side surface 65C of the light guide member 65 at an angle smaller than the critical angle and is refracted to pass through the light guide member 65 and travel downward from the lower side surface 65D.

  Even if a part of the diffused light LK reaches the upper surface of the first holder 51, the first holder 51 is disposed in a range where the relative intensity of the light L is 10% or less. The intensity of the light reflected from the upper surface of one holder 51 and re-irradiated to the surface GA to be read is so small that it hardly affects the reading of the read original G.

  As described above, in the first carriage 18 of the present embodiment, the light LK is prevented from being irradiated again on the read surface GA of the read original G, and the reflected light (diffused light) from the image on the read original G is reduced. The fluctuation of intensity becomes small. And the fall of the brightness | luminance difference (contrast) in the image photoelectrically converted by the photoelectric conversion element 26 (refer FIG. 3) becomes small.

  Further, in the first carriage 18 of the present embodiment, the re-irradiation light to the read surface GA of the read original G is reduced only by moving the position of the end portion 51C of the first holder 51 from the optical axis LT. It is not necessary to perform a surface treatment for suppressing light reflection on the upper surface of the first holder 51, and the structure is less expensive than when using a surface-treated product.

  In addition, this invention is not limited to said embodiment.

  As shown in FIG. 11, a first carriage 130 having a first holder 132 formed with a bent portion 132A may be used. The bent portion 132A is a portion where the upper end is bent at an acute angle (inclination angle θ) downward with respect to the horizontal plane. Here, in the first carriage 130, the light LM reflected at the reflection position X6 located on the reading position X0 side with respect to the reflection position X2 is reflected by the bent portion 132A and proceeds to the light guide member 65, and the light guide member 65 inside. Transparent. In this way, a light guide unit that guides the reflected light LM to the light guide member 65 side may be provided.

  The first carriage 18 may be one in which the first holder 51 is not located above the light guide member 65 and the entire light guide member 65 is exposed.

  In addition to using polycarbonate resin, polyimide resin, glass, or the like as another material of the light guide member 65, a resin material that totally reflects and has a light transmittance of 80% or more may be used. In addition, each embodiment is not limited to reading the read original G on the first platen glass 43A, but may be reading on the second platen glass 43B.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Original reading apparatus (an example of an image reading apparatus)
20 Imaging unit (an example of reading means)
30 Image forming unit (an example of an image forming unit)
51 First holder (an example of an upper member)
61 Light emitting element (an example of a light source)
65 Light guide member (an example of a light guide)
65A light exit surface (example of exit surface)
65B Light incident surface (an example of an incident surface)
65C Upper side (example of side)
65D Lower side (example of side)
132A Bent part (an example of light guiding means)
GA Read surface LT Optical axis

Claims (3)

A light source that emits light;
An incident surface on which light emitted from the light source is incident, an exit surface that emits light toward the read surface, and reflects light incident from the incident surface to the exit surface and from the read surface A light guide body including a side surface that transmits the reflected light of
A reflecting member that reflects part of the light emitted from the exit surface toward the read surface;
A reading unit that receives reflected light from the read surface and reads an image of the read surface;
In the image reading apparatus having,
The side surface includes an upper side surface of the read surface side and a lower side surface facing the upper side surface,
The light incident on the upper side is transmitted to the lower side,
In the light guide, a part of the upper side surface is on the optical axis side of the optical path that guides the reflected light from the read surface to the reading unit with respect to the upper member disposed above the light guide. Protruding,
The upper member has light guide means arranged at an angle from the reflection member toward the read surface and guiding a regular reflection component of light reflected from the read surface to the upper side surface of the light guide. Image reading device.   2. The image reading apparatus according to claim 1, wherein a surface roughness of a side surface of the light guide is 0.1 μm or less as a surface roughness measured by an arithmetic average roughness Ra of JIS-B-0601. The image reading apparatus according to claim 1 or 2,
An image forming unit that forms an image based on information of an image read by the reading unit of the image reading device;
An image forming apparatus .

Images