JP2009260870A - Document feeding and reading device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent quality of a read image from being degraded, and to convey a sheet document with high feeding property, in a document feeding and reading device. <P>SOLUTION: While feeding a sheet document between contact glass 51 and a white reference member 62, image information of the sheet document is read through the contact glass on a read line L by an image reading means 50 at a fixed position. In the document feeding and reading device 200, a gap adjusting means 60 is provided for adjusting a gap between the contact glass and the white reference member on the basis of a document thickness control signal. As the white reference member, a white elastic sheet 62 is provided which includes: the upstream end in a document feeding direction attached to an axial turning holder 66 which is supported turnably around an axial center orthogonal to the document feeding direction A; a downstream end in the document feeding direction placed on a receiving member 67 so as to be freely slid, and a top-most vertex positioned on the reading line, the white elastic sheet being curved to protrude toward a side of the contact glass. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a function of recording an image on a recording material and a function of reading image information of a sheet document, such as a copying machine, a facsimile, or a complex machine thereof. And an image reading apparatus having a function of reading the image information of the sheet original, and in particular, conveying the sheet original and passing the image information of the conveyed sheet original while passing between the contact glass and the white reference member. And a document conveying / reading apparatus that reads through the contact glass and reads by the image reading means at a fixed position.

  The image reading apparatus includes a document fixing / optical system moving method (scanning method) that scans the image surface by scanning the image surface along the image surface of the fixed document and reads the image information of the document, and a predetermined document. There is a document moving / optical system fixing method (sheet through method) in which the image surface of the document is exposed while being conveyed at a speed of 1, and image information of the document is read by an image reading means at a fixed position. In addition, this type of image reading apparatus includes an analog type used in a general image reading apparatus and a digital type using an image sensor such as a CCD. Recently, since it is advantageous for reading a large original and performing various image processing thereafter, a digital type original moving / fixing optical system type image reading apparatus has been widely adopted.

  By the way, in such an image reading apparatus, the illumination unit is turned on at a predetermined timing before the image reading starts, the white reference surface of the white reference member is irradiated, and the reflected light is read to obtain white image data. Then, shading correction is performed by collecting white level correction data. In the conventional image reading apparatus, the white reference member is provided so that a gap is formed between the white reference member and the contact glass. Or it was provided so that it might be pressed and lightly pressed on contact glass.

  Then, in the document conveying / reading apparatus which is an image reading apparatus of the document moving / optical system fixing method, the sheet document is conveyed by the conveying roller during image reading, and the sheet is passed between the contact glass and the white reference member. The image information of the original was read by the image reading means at a fixed position through the contact glass on the reading line.

JP 2003-134307 A JP 2003-324586 A JP 2005-123704 A JP 2006-295658 A

  However, in a document conveying / reading apparatus having a gap between the white reference member and the contact glass, a translucent sheet document such as a second original drawing is conveyed between the white reference member and the contact glass during image reading. The shadow of the image of the sheet original is reflected on the white reference member and is also read by the illumination by the illumination means, and the read image quality is deteriorated. Therefore, there has been a problem that when an image is formed based on such a read image, a smear image (background stain) occurs.

  Also, in a document conveying and reading device in which the white reference member is urged and pressed lightly against the contact glass, when a thin paper document with weak stiffness is passed, the sheet document is buckled by the conveyance resistance and the document is conveyed. Defects occurred, the original was damaged, and the read image quality was also lowered. Therefore, even when image formation is performed based on such a read image, there is a problem that a smear image (background stain) occurs.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to eliminate the possibility that the quality of a read image is lowered and to improve the transportability of a sheet document in the document transport / reading apparatus.

  A second object of the present invention is to facilitate the adjustment of the gap between the contact glass and the white reference member, to eliminate the possibility that the read image quality is easily lowered, and to improve the transportability of the sheet document. is there.

  A third object of the present invention is to enable automatic adjustment of the gap between the contact glass and the white reference member without trouble.

  A fourth object of the present invention is to enable accurate adjustment between the contact glass and the white reference member with an appropriate gap.

  A fifth object of the present invention is to enable automatic detection of a document thickness necessary for adjusting a gap between a contact glass and a white reference member without trouble.

  A sixth object of the present invention is to enable an original thickness control signal to be transmitted to the gap adjusting means at a low cost without complicating the configuration.

  According to a seventh object of the present invention, when a thin paper document with low stiffness is passed, the sheet conveyance resistance is reduced so that the sheet document does not buckle, and there is no possibility that the document will be poorly conveyed. In other words, the read image quality is not deteriorated.

  An eighth object of the present invention is to provide an image forming apparatus provided with a document conveying / reading device which eliminates the possibility of occurrence of a blurring image and has good sheet document conveying properties.

According to the first aspect of the present invention, the sheet original is conveyed and passed between the contact glass and the white reference member. In the document conveyance reading device that is read by the image reading means,
A gap adjusting means for adjusting a gap between the contact glass and the white reference member based on the document thickness control signal is provided.

  Then, at the time of image reading, after adjusting the gap between the contact glass and the white reference member to an appropriate gap by the gap adjusting means based on the original thickness control signal, the sheet original to be conveyed while passing the sheet original through the gap The image information is read by the image reading means at a fixed position through the contact glass in the reading line.

  According to a second aspect of the present invention, in the document conveying / reading apparatus according to the first aspect, the original is placed on the shaft-like rotation holder supported as a white reference member so as to be rotatable about an axis perpendicular to the document conveying direction. A white end that is attached to the upstream end in the transport direction, is slidably placed on the receiving member in the downstream direction in the document transport direction, has a vertex on the reading line, and is curved so as to be convex toward the contact glass side. An elastic sheet is provided.

  When reading an image, the shaft-shaped rotation holder is rotated based on the document thickness control signal to change the curvature of the white elastic sheet, and the clearance adjustment means provides a suitable clearance between the contact glass and the white reference member. Adjust to.

  According to a third aspect of the present invention, in the document conveying / reading device according to the second aspect, the gap adjusting means is driven to rotate the shaft-like rotating holder forward and backward based on the document thickness control signal, and the white elastic sheet. A drive means such as a step motor for changing the curvature of curvature is provided. Then, at the time of image reading, based on the document thickness control signal, the driving means rotates the shaft-like rotation holder to change the curvature of curvature of the white elastic sheet.

  According to a fourth aspect of the present invention, in the document conveying / reading device according to the second or third aspect, a distance detection unit provided in the reading line and detecting a distance to the back surface of the white elastic sheet is provided, and when reading an image. Is characterized in that, based on the detection result of the distance detection means, the shaft-like rotation holder is rotated and adjusted so that the original thickness is based on the original thickness control signal.

  According to a fifth aspect of the present invention, in the original conveying / reading apparatus according to any one of the first to fourth aspects, an original thickness detecting means for detecting an original thickness is provided at an upstream position of the reading line, A document thickness control signal is transmitted to the gap adjusting unit based on the detection result of the document thickness detecting unit.

  According to a sixth aspect of the present invention, in the original conveying / reading apparatus according to any one of the first to fourth aspects, an operation unit for inputting a type of the original is provided. A thickness control signal is transmitted. Then, the user operates the operation unit to input a document type, and based on the input result, a document thickness control signal is transmitted to the gap adjusting means.

  According to a seventh aspect of the present invention, in the original conveying / reading apparatus according to the fifth or sixth aspect, for a thin paper original, an original thickness that forms a gap between the contact glass and the white reference member in the gap adjusting means. The control signal is controlled to be transmitted.

  The invention according to claim 8 is a copy which records an image on a recording material such as paper, resin film, etc., comprising the document conveying / reading device according to any one of claims 1 to 7. Image forming apparatus such as a printer or a facsimile machine.

  According to the first aspect of the present invention, when the image is read in the document conveying / reading apparatus, the gap adjusting means adjusts the gap between the contact glass and the white reference member to an appropriate gap based on the document thickness control signal. When a semi-transparent sheet original such as a second original drawing is transported between the white reference member and the contact glass, a gap is not formed between the sheet original and the white reference member, and it is illuminated by illumination means. Further, it is possible to prevent the shadow of the image of the sheet document from appearing on the white reference member, and it is possible to eliminate the possibility of reading the shadow and degrading the read image quality. In addition, since the conveyance resistance is small, even when a thin paper document with a low stiffness is passed, the sheet document is not buckled, the document conveyance is improved, the document is damaged, and the read image quality is similarly improved. The risk of lowering can be eliminated.

  According to the second aspect of the present invention, the shaft-shaped rotation holder is rotated based on the document thickness control signal to change the curvature of curvature of the white elastic sheet, and the contact glass and the white reference member in the gap adjusting means are changed. Since the gap between the contact glass and the white reference member is easily adjusted, it is easy to adjust the gap between the contact glass and the white reference member. be able to.

  According to the third aspect of the present invention, when reading an image, based on the document thickness control signal, the driving means rotates the shaft-shaped rotation holder to change the curvature of curvature of the white elastic sheet. The gap between the white reference member and the white reference member can be automatically adjusted by the gap adjusting means. If a step motor is used as the driving means, the gap between the contact glass and the white reference member can be adjusted more easily and accurately.

  According to the fourth aspect of the present invention, the distance detection means for detecting the distance to the back surface of the white elastic sheet is separately provided in the reading line, and when reading an image, the document is based on the detection result of the distance detection means. Since the shaft-like rotation holder is rotated and adjusted so as to have an appropriate document thickness based on the thickness control signal, the gap between the contact glass and the white reference member can be accurately adjusted to an appropriate gap.

  According to the fifth aspect of the present invention, the document thickness detecting means is provided, and the document thickness control signal is transmitted to the gap adjusting means based on the detection result of the document thickness detecting means. The thickness detection of the sheet document necessary for adjusting the gap with the reference member can be automatically performed without trouble by the document thickness detection means.

  According to the sixth aspect of the present invention, the user operates the operation unit to input the document type, and based on the input result, the document thickness control signal is transmitted to the gap adjusting means. A document thickness control signal can be transmitted to the gap adjusting unit at low cost without providing a detecting unit or the like to complicate the configuration.

  According to the seventh aspect of the present invention, for a thin paper document, control is performed so that a document thickness control signal that creates a gap between the contact glass and the white reference member is transmitted to the gap adjusting means. Therefore, when a thin paper document with low stiffness is passed, the sheet conveyance resistance is reduced, the sheet document is not buckled, the document is not likely to cause a conveyance failure, the document is damaged, or the scanned image is scanned. Quality can be prevented from deteriorating.

  According to the eighth aspect of the present invention, since the image forming apparatus includes the original conveying / reading apparatus according to any one of the first to seventh aspects, the image having the original conveying / reading apparatus having the above-described effect. A forming apparatus can be provided.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of a main part of an image forming apparatus provided with a document conveying / reading apparatus. In the figure, reference numeral 100 denotes an image forming apparatus main body, and reference numeral 200 denotes a sheet-through type document conveying and reading apparatus mounted on the image forming apparatus main body 100.

  First, the image forming apparatus main body 100 includes a drum-shaped image carrier 10 that rotates counterclockwise in the drawing. Around the image carrier 10, an exposure device 13, a developing device 14, a transfer separation device 15, a cleaning device 16, a charge removal device 17, and the like are arranged in this order from the charging device 12 installed above in the rotation direction. Yes.

  Below the image carrier 10, a recording material conveyance path through which a recording material such as paper and resin film is conveyed from the left to the right in the drawing through a transfer separation position T with the transfer separation device 15. 18 is formed. In the recording material conveyance path 18, a registration roller pair 20 is provided upstream of the transfer separation position T, and a recording material conveyance device 22, a fixing device 23, and a conveyance roller pair 24 are sequentially installed downstream. The recording material conveyance path 18 is branched into a paper refeed path 25 and a paper discharge path 26 downstream of the position of the conveyance roller pair 24, and a switching lever 27 is disposed at the branch position. The paper discharge path 26 is formed so as to be reversed upward, and a paper discharge roller pair 28 is provided at the most downstream position.

  On the image forming apparatus main body 100, a paper discharge receiver 30 for receiving a recording material discharged by the paper discharge roller pair 28 is formed. Although not shown, a duplex unit is attached to the back surface (right side in the figure) of the image forming apparatus main body 100. The duplex unit reverses the recording material conveyed through the refeed path 25 and returns it to the image forming apparatus main body 100, and refeeds the recording material to the upstream position of the registration roller pair 20 through the image forming apparatus main body 100.

  Next, the document conveying / reading apparatus 200 is provided with an opening / closing device 400 on the reading device main body 300 so as to be freely opened / closed with the back side as a fulcrum. Between them, a document transport path 40 through which a sheet document is transported from left to right in the figure is formed substantially horizontally and straight. In the document transport path 40, a document placing table 42 on which a sheet document is stacked and placed with the reading image surface facing down is provided on the reading apparatus main body 300 at the most upstream position with the upper part opened.

  On the side of the reading apparatus main body 300, the driving roller 54 of the upstream conveying roller pair 63, the light receiving unit 52 b of the registration detection sensor 52, and the image reading unit 50 are sequentially arranged along the original conveying path 40 from the original placing table 42 in the original conveying direction. Further, a drive roller 55 of the downstream side conveyance roller pair 64 and the like are provided.

  The image reading means 50 is a fixed-type reading sensor that is provided with a fixed position and reads image information of a sheet document conveyed on the document conveyance path 40. As shown in detail in FIG. 2 to be described later, the image reading unit 50 is provided with a contact glass 51 facing the document conveyance path 40, two illumination units 50a for irradiating the conveyed document D with light, and a document An imaging lens 50b that converges the reflected light from D and an image sensor 50c that photoelectrically converts the light converged by the imaging lens 50b and imaged on the light receiving surface are provided.

  On the other hand, on the opening / closing device 400 side, as shown in FIG. 1, the size detection sensor 56, the driven roller 57 of the upstream conveyance roller pair 63, the registration detection sensor, in order from the upstream in the document conveyance direction along the document conveyance path 40. 52, a white elastic sheet 62 as a white reference member, a paper discharge detection sensor 53, a driven roller 58 of the downstream side conveyance roller pair 64, and the like.

  In the opening / closing device 400, a branch discharge path 44 is formed by branching from the document transport path 40 at a position downstream of the downstream transport roller pair 64. The branch discharge path 44 is formed upward, curved and folded, and is provided with a discharge roller pair 46 at the exit position. An operation unit 59 is provided on the front side of the opening / closing device 400 so as to face the front.

  A switching lever 48 is disposed at a position where the branch discharge path 44 branches from the document transport path 40. The switching lever 48 is provided to be switchable between a first position and a second position. When the switching lever 48 is switched to the first position, the image-read sheet original conveyed on the original conveying path 40 advances straight in the original conveying path 40 in the direction of the arrow b, and the image reading apparatus. The sheet is discharged onto a first tray 45 attached horizontally to 200. On the other hand, when the switching lever 48 is switched to the second position, the image-read sheet original conveyed on the original conveyance path 40 proceeds to the branch discharge path 44, is reversed and conveyed, and reaches the most downstream side. The paper is conveyed in the direction of the arrow c by the installed discharge roller pair 46 and is discharged onto the second tray 47 that is externally mounted on the image reading apparatus 200.

  The two drive rollers 57 and 58 are configured by providing a plurality of rubber rollers at intervals on each roller shaft. The two drive rollers 57 and 58 are provided in parallel with each other at intervals in the document transport direction, and both ends of the roller shaft are not provided. Each of the illustrated cases is supported via a bearing. A white elastic sheet 62 is provided on the reading line L of the image reading unit 50 between the two drive rollers 57 and 58. Then, the driven roller 54 is pressed against the driving roller 57 by a biasing member (not shown) to form an upstream-side conveyance roller pair 63, and the driven roller 55 is pressed against the driving roller 58 by a biasing member (not shown). Thus, a pair of downstream side conveyance rollers 64 is formed.

  Now, when a plurality of sheet originals are to be copied using the illustrated image forming apparatus as described above, the sheet originals are stacked and set on the original placement table 42, and the start switch of the operation unit 59 is set. Turn on. Then, before starting the image reading, after the black level correction data is collected, the illumination means is turned on at a predetermined timing to read the white elastic sheet 62, and the white level correction data is collected using the white image data at that time. Then, shading correction for correcting the sensitivity of the reading sensor 50 is executed.

  After performing the shading correction, a scanner motor constituted by a step motor (not shown) is driven, and the driving force is transmitted to the drive rollers 57 and 58 via a drive transmission means such as a timing belt. Then, the sheet document on the document table 42 is fed in the direction of arrow a in FIG. 1 by the rotation of a feed roller (not shown), and after the insertion of the sheet document is detected by the size detection sensor 56, It is inserted between the driven roller 54 and conveyed through the document conveying path 40 by the upstream conveying roller pair 63, and the image information of the conveyed document is read line while passing between the contact glass 51 and the white elastic sheet 62. At L, the contact glass is passed through and is read by the image reading means 50 at a fixed position. Then, the image-read sheet original is conveyed by the downstream conveying roller pair 64, switched by the switching lever 48, and discharged onto the first tray 45 or the second tray 47.

  At this time, the size detection sensor 56 detects the insertion of the document, detects the document size, pauses in front of the registration detection sensor 52, re-rotates the scanner motor after an arbitrarily set waiting time, and reads the image. 50 and the white elastic sheet 62. Then, after a predetermined number of pulses have elapsed since the registration detection sensor 52 detected the leading edge of the document, the image reading means 50 starts reading the read image surface, and then the paper discharge detection sensor 53 passes the document. Detect.

  The drive roller 57 is driven and controlled via an electromagnetic brake clutch, and is driven by the electromagnetic brake clutch being actuated by a document insertion detection signal from the size detection sensor 56. The electromagnetic brake clutch is disengaged at a predetermined arbitrary position after the leading edge of the document passes the driving roller 55 and then the trailing edge of the document passes the size detection sensor 56. The next document cannot be inserted until it is ejected from the printer. Further, the driving force of the scanner motor is also transmitted to the discharge roller pair 46 through a gear and a timing belt. Here, the peripheral speed of each document conveying roller is made slightly higher in order, so that the document does not sag between the rollers.

  In this example, the rotation speed of the scanner motor is controlled in a pattern in which the rotation speed is determined so as to be the document conveyance speed. The rotation speed at the time of zooming is controlled by the rotation speed at the same magnification divided by 100% when the same magnification is set to 100%. For example, when 10% at 100%, the rotation speed is 20 rpm at 50%. It will be.

  In the image forming apparatus main body 100, the image carrier 10 is rotated and the surface is uniformly charged by the charging device 12, and then writing is performed by the exposure device 13 based on the reading content of the contact image sensor 50 to form an electrostatic latent image. After that, the electrostatic latent image is developed by attaching toner with the developing device 14 to form a toner image on the image carrier 10.

  On the other hand, the recording material is fed at an appropriate timing from the recording material setting position and conveyed through the recording material conveyance path 18, and the recording material is fed to the transfer separation position T by the registration roller pair 20 at the timing. The toner image formed on the carrier 10 is transferred to the recording material by the transfer separation device 15, and the recording material after the toner image is transferred is separated from the image carrier 10 and conveyed by the recording material conveyance device 22 to be fixed by the fixing device 23. After the transfer image is fixed, the switching lever 27 switches the sheet to convey it in the direction of the arrow d, and the sheet is discharged onto the sheet receiving tray 30. When an image is also formed on the back side, it is switched by the switching lever 27 and conveyed in the direction of the arrow e, and is reversed and fed again by a duplex unit (not shown).

FIG. 2 shows an enlarged configuration of a main part of the document conveying / reading apparatus 200.
As shown in the figure, a gap adjusting means 60 is provided in the opening / closing device 400 of the document conveying / reading apparatus 200 so as to face the image reading means 50 of the reading apparatus main body 300. The gap adjusting means 60 includes the above-described white elastic sheet 62 made of a PET film sheet, a shaft-like rotating holder 66 whose upstream end side in the document conveying direction indicated by arrow A in the drawing is fixed by a set screw 65, white A step in which the downstream end side of the elastic sheet 62 in the document conveying direction A is connected to the shaft-like rotation holder 66 through a receiving member 67 slidably mounted, and a drive transmission means (not shown) such as a gear. A motor 68, a distance sensor 69 that is a distance detecting means, and the like are provided.

  The shaft-like rotation holder 66 is supported by a housing (not shown) so as to be rotatable about an axis perpendicular to the document conveying direction A. A detection plate (not shown) is attached to the detection plate. The home position is determined by detecting with a transmission sensor. The receiving member 67 also has an axial shape, and both ends thereof are supported by a housing (not shown) in a direction orthogonal to the document conveying direction A. As a result, the white elastic sheet 62 is curved and provided so that the apex is positioned on the reading line L and is convex toward the contact glass 51 side.

  Then, based on the original thickness control signal, the step motor 68 is driven to drive the shaft-like rotation holder 66 forward and reverse, and the support angle of the upstream end of the white elastic sheet 62 is changed to downstream of the white elastic sheet 62. The end side slides on the receiving member 67 and changes the curvature of the white elastic sheet 62 so that the gap between the contact glass 51 and the white elastic sheet 62 can be adjusted.

  A distance sensor 69 that detects the distance to the back surface of the white elastic sheet 62 and adjusts the gap between the contact glass 51 and the white elastic sheet 62 is installed on the reading line L on the back side of the white elastic sheet 62. ing. In a normal state, the distance to the back surface of the white elastic sheet 62 is detected, and the shaft-like rotation holder 66 is rotated so that the surface of the white elastic sheet 62 comes into light contact with the contact glass 51. At the time of reading, the distance to the back surface of the white elastic sheet 62 is detected, and the shaft-like rotation holder 66 is rotated and adjusted so that the original thickness is based on the original thickness control signal.

  On the other hand, an upstream side conveying roller pair 63 position, which is an upstream position of the reading line L, includes an original thickness detecting means 70 for detecting the original thickness in order to transmit an original thickness control signal to the gap adjusting means 60. It has been. In FIG. 2, the size detection sensor 56, the registration detection sensor 52, the paper discharge detection sensor 53, and the like shown in FIG. 1 are not shown.

FIG. 3 shows the position of the original thickness detecting means 70 in an enlarged manner, where (A) is a flat surface and (B) is a side surface.
As shown in the figure, the document thickness detection means 70 is pressed by a distance detection sensor 71 for detecting the distance to the back surface of the document D, a guide mylar (registered trademark) 72 supported by the housing, and the guide mylar 72. And a reference plate 73 through which the document D passes in contact. When the transported document D passes the position of the distance detection sensor 71, the distance to the reference plate 73 is set to 0, the distance to the back side of the document is detected by the distance detection sensor 71, and the document thickness detection unit 70 detects the document D. Detect thickness.

  Then, the detection result is sent to a control device (not shown), a document thickness control signal is issued from the control device, the step motor 69 is driven based on the document thickness control signal, and the shaft shape is transmitted via the drive transmission means. The rotation holder 66 is rotated forward and backward to change the curvature of curvature of the white elastic sheet 62 and adjust the gap with the contact glass 51 to be slightly larger. That is, in FIG. 2, when rotating in the B direction, the curvature curvature increases and the gap with the contact glass 51 increases. Conversely, when rotating in the C direction, the curvature curvature decreases and the clearance with the contact glass 51 decreases. Become. Thereafter, the distance sensor 69 detects the distance to the back surface of the white elastic sheet 62 and controls the step motor 68 based on the detection result to adjust the thickness of the document D detected by the document thickness detection means 70.

  In this example, the distance sensor 69 is provided. However, without providing the distance sensor 69, the relationship between the number of drive pulses of the step motor 68 and the amount of displacement of the white elastic sheet 62 is obtained in advance by experiment, and from this relationship The gap between the white elastic sheet 62 and the contact glass 51 may be directly adjusted based on the detection result of the document thickness detection means 70.

  Further, by inputting the type of the original D from the operation unit 59 without providing the original thickness detecting means 70, an original thickness control signal is transmitted to the gap adjusting means 60 based on the input result. The step motor 69 is driven based on the document thickness control signal, and the shaft-like rotation holder 66 is rotated forward and backward via the drive transmission means, and the curved curvature of the white elastic sheet 62 is changed to form a gap with the contact glass 51. You may make it adjust.

  In the case of a thin paper document, it is preferable to control so that a document thickness control signal that creates a gap between the contact glass 51 and the white reference member is transmitted. In this way, when a thin paper document having a low stiffness is passed, a gap is formed between the contact glass 51 and the white reference member to reduce the conveyance resistance of the document, and the sheet document is not buckled. It is possible to prevent the occurrence of a conveyance failure and prevent the original from being damaged and the quality of the read image from being deteriorated.

1 is a schematic configuration diagram of a main part of an image forming apparatus provided with a document conveyance reading device. FIG. 3 is an enlarged view of a main part configuration of the document conveying / reading apparatus. The position of the original thickness detecting means is shown enlarged, (A) is a plan view and (B) is a side view.

Explanation of symbols

50 Image reading means (contact type reading sensor)
51 Contact Glass 59 Operation Unit 60 Clearance Adjusting Means 62 White Elastic Sheet (White Elastic Sheet)
66 Shaft-shaped rotation holder 67 Receiving member 68 Step motor 69 Distance sensor (distance detection means)
70 Document Thickness Detection Unit 100 Image Forming Apparatus Main Body 200 Document Conveying Image Reading Apparatus A Document Conveying Direction D Document L Reading Line

Claims (8)

In a document conveying and reading apparatus that conveys a sheet document and passes between the contact glass and the white reference member and reads the image information of the sheet document through the contact glass through a reading line by an image reading unit at a fixed position.
An original conveying / reading apparatus, comprising: a gap adjusting means for adjusting a gap between the contact glass and the white reference member based on an original thickness control signal.   As the white reference member, an upstream end in the document transport direction is attached to a shaft-shaped rotation holder that is rotatably supported about an axis orthogonal to the document transport direction, and a downstream end in the document transport direction is slidable on the receiving member. 2. A white elastic sheet that is placed on the reading line and has a vertex located on the reading line and is curved so as to be convex toward the contact glass side is provided. Document conveying and reading apparatus.   The gap adjusting means is provided with driving means for changing the curvature of curvature of the white elastic sheet by driving the shaft-like rotation holder forward and backward based on the original thickness control signal. The document conveying / reading apparatus according to claim 2.   A distance detection unit is provided in the reading line and detects the distance to the back surface of the white elastic sheet. When reading an image, the document based on the document thickness control signal is based on the detection result of the distance detection unit. The document conveying / reading apparatus according to claim 2, wherein the shaft-like rotation holder is rotationally adjusted so as to have a thickness.   An original thickness detecting means for detecting the original thickness is provided at an upstream position of the reading line, and the original thickness control signal is transmitted to the gap adjusting means based on the detection result of the original thickness detecting means. The document conveyance reading apparatus according to claim 1, wherein   The operation unit for inputting a document type is provided, and based on the input result, the document thickness control signal is transmitted to the gap adjusting means. Document conveying and reading apparatus.   7. The thin paper document is controlled so that the document thickness control signal that creates a gap between the contact glass and the white reference member is transmitted. Document conveying and reading apparatus.   An image forming apparatus comprising the document conveying / reading device according to claim 1.

Images