JP4424091B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image of an original, and more particularly, to an image reading apparatus that reads an image of a conveyed original.

2. Description of the Related Art Conventionally, as a reading device such as a copying machine or a facsimile, or a scanner device for computer input, an image reading device that reads an image formed on the original while conveying the original is known.
In general, when reading a document, for example, a method of irradiating light with a fluorescent lamp as a light source and reading the reflected light with an optical sensor via a reduction optical system is adopted. As a sensor in such a system, for example, a one-dimensional CCD (Charge Coupled Device) sensor is used, and one line is processed simultaneously. When reading of one line in this line direction (scanning main scanning direction) is completed, the original is moved by a minute distance in a direction (sub-scanning direction) perpendicular to the main scanning direction, and the next line is read. This is repeated over the entire document size to complete one page of document reading. In this reading method, it is necessary to apply a light source to an original and read the reflected light with a CCD sensor via several mirrors, so that the entire unit tends to be large. Therefore, in order to solve such a space problem, an LED (Light Emitting Diode) having a small shape is used as a light source, and for example, an image is directly read by a linear sensor via a Selfoc lens (registered trademark). The use of a contact-type image sensor called CIS (Contact Image Sensor) has been studied.

In the reading method using the CIS, the depth of focus is very shallow compared to the reading method using the reduction optical system, and if the distance between the CIS and the document surface is slightly out of focus, the focus is shifted, and the read image is displayed. It will be out of focus. That is, although the entire apparatus can be reduced, it is difficult to realize a sharp image. Therefore, conventionally, for example, a technique has been used in which a document is brought into close contact with a CIS reading surface using a pressing roll or the like to suppress blurring of a read image (see Patent Document 1).
However, when reading is performed using such a method, there is a possibility that dirt or dust on the original such as toner attached to the original or ballpoint pen ink may adhere to the reading surface of the CIS. If dirt or dust adheres to the CIS reading surface in this way, streaks are generated in the sub-scanning direction of the read image data, leading to poor reading.

  On the other hand, for example, a transparent glass plate is arranged at a predetermined distance from the reading sensor so as to face a reading sensor such as CIS, and the original is conveyed in an oblique direction so that the original abuts against the glass plate. Has been proposed (see Patent Document 2). Further, in Patent Document 2, a plate-shaped presser spring is placed in contact with a glass plate, and the conveyed document is forcibly brought into close contact with the glass plate by the presser spring, thereby reducing the distance between the document and the reading sensor. Techniques for maintaining it constant are also described.

Japanese Patent Laid-Open No. 5-114974 (2nd page, FIG. 1) Japanese Patent Laid-Open No. 10-190938 (page 3-4, FIG. 1)

  However, when the former method in Patent Document 2 is used, when reading a curled document or a folded document, the document cannot be brought into contact with a glass plate such as a curled portion or a folded portion. There was a risk of the formation of a site. In this way, in a portion where the original cannot be brought into contact with the glass plate, the read image is defocused.

  Further, when the latter method in Patent Document 2 is used, since the holding spring is pressed against the glass plate, the conveyed document is sandwiched between the glass plate and the holding spring and the original is jammed. Could occur. In such a case, the original image cannot be read. Furthermore, a so-called double-sided image sensor is provided that reads another surface of the document on the opposite side of the document in the upstream of the document conveyance direction so as to read the image formed on both sides of the document with a single document conveyance. In the simultaneous reading device, when the leading end of the document in the conveyance direction enters between the glass plate and the holding spring, the document conveyance speed fluctuates temporarily. There is a possibility that the read image is extended and disturbed.

The present invention has been made in order to solve such technical problems, and the object of the present invention is to suppress jamming of a conveyed document while reading an image of the conveyed document, The purpose is to position the conveyed document at the reading position.
Another object is to suppress the disturbance of the read image due to the disturbance of the conveyance of the original when the images on both sides of the original are read by the single conveyance of the original.

For this purpose, an image reading apparatus to which the present invention is applied includes a reading unit that reads an image of a conveyed document, a facing member that is disposed opposite the reading unit with the conveyed document interposed therebetween, and a document that is conveyed. And a guide member that guides the original so that the original to be conveyed is abutted against the original conveying surface.
Here, the reading unit may be a CIS (Contact Image Sensor). Further, the gap may be 0.1 to 1.0 mm. Furthermore, the guide member is made of a metal plate, and the end portion on the side in contact with the document is bent.

From another point of view, an image reading apparatus to which the present invention is applied includes a reading unit that reads an image of a conveyed document, a counter member that is disposed to face the reading unit across the conveyed document, A guide member that guides the conveyed document to the opposing member; a gap forming unit that forms a gap between the opposing member and the guide member; and a biasing unit that biases the guide member toward the opposing member. .
Here, the gap forming means may be characterized in that a gap of 0.1 to 1.0 mm is formed between the opposing member and the guide member. Further, the gap forming means has a rib shape that protrudes from both ends of the opposing member in the direction orthogonal to the document conveyance direction toward the reading unit and extends along the document conveyance direction. Can be a feature.

Further, from another viewpoint, an image reading apparatus to which the present invention is applied includes a conveyance path through which a document is conveyed, a first reading unit that reads a first surface of a document from one side of the conveyance path, A second reading unit that is provided downstream of the first reading unit in the document conveyance direction and reads an image on the second surface of the document from the other side of the conveyance path is disposed opposite to the second reading unit. It includes a counter member, and a guide member that is disposed with a predetermined gap from the document conveyance surface of the counter member and guides the document so that the conveyed document is abutted against the document conveyance surface.
Here, the second reading unit may be a CIS (Contact Image Sensor). Further, the gap may be 0.1 to 1.0 mm.

  According to the present invention, in an image reading apparatus that reads an image of a conveyed document, it is possible to position the conveyed document at a reading position while suppressing the document jam or the speed fluctuation of the document.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing an image reading apparatus to which the present embodiment is applied. This image reading apparatus is roughly divided into a document feeding device 10 that sequentially conveys documents from a stacked document bundle, a scanner device 70 that reads an image by scanning, and a processing device 80 that processes the read image signal. Is done.

  The document feeder 10 includes a document tray 11 on which a bundle of documents composed of a plurality of documents is stacked, and a tray lifter 12 that raises and lowers the document tray 11. Further, a nudger roll 13 that conveys the original on the original tray 11 raised by the tray lifter 12, a feed roll 14 that conveys the original conveyed by the nudger roll 13 further downstream, and an original supplied by the nudger roll 13. Are provided with a retard roll 15. In the first conveyance path 31 where the original is first conveyed, a take-away roll 16 that conveys the originals that are being fed one by one to the downstream roll, and further conveys the original to the further downstream roll and creates a loop. The pre-registration roll 17 to be performed, the rotation is resumed at the timing after stopping once, the registration roll 18 for supplying the original while adjusting the registration to the original reading unit, the platen roll 19 for assisting the conveyance of the original being read, An out-roll 20 is provided for conveying the read original further downstream. The first conveyance path 31 as a conveyance path is provided with a baffle 41 that rotates around a fulcrum according to the loop state of the conveyed document. Further, a CIS (Contact Image Sensor) 50 as a reading unit (second reading unit) is provided between the platen roll 19 and the out-roll 20.

  A second transport path 32 and a third transport path 33 are provided on the downstream side of the out-roll 20, a transport path switching gate 42 for switching between these transport paths, a discharge tray 40 for stacking documents that have been read, and a discharge tray A first discharge roll 21 that discharges the original document 40 is provided. In addition, an inverter roll 22 and an inverter pinch roll 23 that are provided in the fourth transport path 34 and the fourth transport path 34 for switching back the document that has passed through the third transport path 33 and actually switch back the document, The document switched back by the fourth transport path 34 is again guided to the first transport path 31 including the pre-registration roll 17 and the like, and the document switched back by the fourth transport path 34 is discharged to the discharge tray 40. The transport paths of the second discharge roll 24, the fifth transport path 35, and the sixth transport path 36 that are provided in the sixth transport path 36 and the sixth transport path 36 and transport the inverted document to the first discharge roll 21. An exit switching gate 43 for switching is provided.

  The nudger roll 13 is lifted up and held at the retracted position during standby, and descends to the nip position (original conveyance position) during conveyance of the document to convey the uppermost document on the document tray 11. The nudger roll 13 and the feed roll 14 convey a document by connecting a feed clutch (not shown). The pre-registration roll 17 makes a loop by abutting the leading end of the document against the stopped registration roll 18. In the registration roll 18, when the loop is created, the leading edge of the document bitten by the registration roll 18 is returned to the nip position. When this loop is formed, the baffle 41 opens around the fulcrum and functions so as not to disturb the document loop. Further, the take away roll 16 and the pre-registration roll 17 hold a loop during reading. By this loop formation, the read timing can be adjusted, and the skew associated with the document conveyance at the time of reading can be suppressed, and the alignment adjustment function can be enhanced. The stopped registration roll 18 starts rotating in accordance with the start timing of reading, and is pressed against the second platen glass 72B (described later) by the platen roll 19 to read the image data from the lower surface direction.

  The conveyance path switching gate 42 switches so that the document passing through the out-roll 20 is guided to the second conveyance path 32 and discharged to the discharge tray 40 at the end of reading one-sided document and at the same time when reading both-side documents simultaneously. It is done. On the other hand, the transport path switching gate 42 is switched so as to guide the document to the third transport path 33 in order to invert the document when the double-sided document is sequentially read. The inverter pinch roll 23 is retracted with the feed clutch (not shown) turned off during sequential reading of the double-sided document to open the nip, and guides the document to the inverter path (fourth conveyance path 34). Thereafter, the inverter pinch roll 23 is nipped, the original to be inverted by the inverter roll 22 is guided to the pre-registration roll 17, and the original to be reversed is conveyed to the second discharge roll 24 in the sixth conveyance path 36.

  The scanner device 70 can include the document feeding device 10 described above, supports the document feeding device 10 with a device frame 71, and reads an image of a document conveyed by the document feeding device 10. The scanner device 70 is being transported by a first platen glass (platen glass) 72A for placing a document to be read in a stationary state on a device frame 71 forming a first housing, and a document feeder 10. A second platen glass 72B is provided to form a light opening for reading the original. In the present embodiment, the document feeder 10 is attached to the scanner device 70 so as to be swingable with the back side as a fulcrum. When the document is set on the first platen glass 72A, the document feeder 10 is fed. The apparatus 10 is lifted to place a document, and then the document feeder 10 is lowered to the scanner device 70 and pressed.

  The scanner device 70 serving as a first reading unit includes a full-rate carriage 73 and a full-rate carriage 73 that are stationary under the second platen glass 72B and scan the entire first platen glass 72A to read an image. A half-rate carriage 75 for providing the obtained light to the image coupling unit is provided. The full-rate carriage 73 is provided with an illumination lamp 74 that irradiates light on the original and a first mirror 76A that receives reflected light obtained from the original. Further, the half-rate carriage 75 is provided with a second mirror 76B and a third mirror 76C that provide the light obtained from the first mirror 76A to the imaging unit. Further, the scanner device 70 includes an imaging lens 77 that optically reduces the optical image obtained from the third mirror 76C, and a CCD (Charge Coupled Device) that photoelectrically converts the optical image formed by the imaging lens 77. ) An image sensor 78 and a drive substrate 79 having a CCD image sensor 78 are provided, and an image signal obtained by the CCD image sensor 78 is sent to the processing device 80 through the drive substrate 79.

  Here, first, when reading an image of a document placed on the first platen glass 72A, the full rate carriage 73 and the half rate carriage 75 move in the scanning direction (arrow direction) at a ratio of 2: 1. . At this time, the light of the illumination lamp 74 of the full rate carriage 73 is irradiated on the surface to be read of the document, and the reflected light from the document is reflected in the order of the first mirror 76A, the second mirror 76B, and the third mirror 76C. Then, it is guided to the imaging lens 77. The light guided to the imaging lens 77 forms an image on the light receiving surface of the CCD image sensor 78. The CCD image sensor 78 is a one-dimensional sensor and processes one line at the same time. When reading of one line in this line direction (main scanning direction of scanning) is completed, the full-rate carriage 73 is moved in a direction (sub-scanning direction) orthogonal to the main scanning direction to read the next line of the document. By executing this over the entire document size, reading of one page of the document is completed.

  On the other hand, the second platen glass 72B is constituted by a transparent glass plate having a long plate-like structure, for example. A document conveyed by the document feeder 10 passes over the second platen glass 72B. At this time, the full-rate carriage 73 and the half-rate carriage 75 are stopped at the solid line positions shown in FIG. First, the reflected light of the first line of the document that has passed through the platen roll 19 of the document feeder 10 is imaged by the imaging lens 77 via the first mirror 76A, the second mirror 76B, and the third mirror 76C. An image is read by the CCD image sensor 78. That is, after one line in the main scanning direction is simultaneously processed by the CCD image sensor 78 which is a one-dimensional sensor, the next line in the main scanning direction of the original conveyed by the original feeding device 10 is read. After the leading edge of the document reaches the reading position of the second platen glass 72B, the document passes through the reading position of the second platen glass 72B, whereby reading of one page is completed in the sub-scanning direction.

  In the present embodiment, the full-rate carriage 73 and the half-rate carriage 75 are stopped, and the first platen glass 72B is used to read the first surface of the document by the CCD image sensor 78. It is possible to read the second side of the original by the CIS 50 (meaning that it is not coincident but the same as when the same original is conveyed). That is, by using the CCD image sensor 78 and the CIS 50, it is possible to read the images on both the front and back sides of the original by one conveyance of the original to the conveyance path.

  FIG. 2 is a diagram for explaining a reading structure using the CIS 50. As shown in FIG. 2, the CIS 50 is provided between the platen roll 19 and the out roll 20. One side (first side) of the original is pressed against the second platen glass 72B, and the image on the first side is read by the CCD image sensor 78. On the other hand, in the CIS 50, an image on one side (second side) is read from the other side facing through a conveyance path for conveying a document. The CIS 50 includes a housing 50a, a glass 51 attached to an opening formed on the conveyance path side of the housing 50a, and an LED (Light Emitting Diode) that transmits light through the glass 51 to the second surface of the document. An array 52, a Selfoc lens (registered trademark) 53 that condenses the reflected light from the LED array 52, and a line sensor 54 that reads the light collected by the Selfoc lens 53 are provided. As the line sensor 54, a CCD, a CMOS sensor, a contact sensor, or the like can be used, and an image with an actual width (for example, A4 longitudinal width 297 mm) can be read. In the CIS 50, since the image is captured using the SELFOC lens 53 and the line sensor 54 without using the reduction optical system, the structure can be simplified, the housing can be downsized, and the power consumption can be reduced. Can be reduced. When reading a color image, the LED array 52 is combined with LED light sources of three colors of R (red), G (green), and B (blue), and a set of three rows of RGB three-color sensors is used as the line sensor 54. Use it.

  Further, when the image is read by the CIS 50, a control member that extends toward the downstream side in the transport direction of the document from a projecting portion 50b that protrudes on the upstream side in the transport direction of the document with respect to the housing 50a of the CIS 50 in the transport path constituting the reading unit. 55, an abutting member 60 as an opposing member against which the conveyed document is abutted. Here, the control member 55 is attached to the document feeder 10 (see FIG. 1) via the CIS 50, but the abutting member 60 is attached to the scanner device 70 (see FIG. 1). In addition, a guide 61 is provided on the downstream side of the abutting member 60, an opening 63 is formed between the guide 61 and the abutting member 60, and the opening 63 is a lower portion of the guide 61. A dust storage portion 62 for collecting dust and dirt adhering to the surface of the document is provided at a portion continuing to the front. The control member 55 and the abutting member 60 are positioned in the conveyance path from the front surface to the rear surface of the document feeder 10 in a direction orthogonal to the document conveyance path (that is, from the front surface to the rear surface of the document feeder device 10). Correspondingly provided.

  Here, the control member 55 is supported by a rotating shaft 551 formed of a screw attached to the above-described projecting portion 50b, and is swingably supported by one end being wound around the rotating shaft 551. A free end which is an end is wound around a guide member 552 as a plate-like guide member extending toward the abutting member 60 and the rotary shaft 551, and an end portion of one arm is formed on the protruding portion 50b. It has a torsion spring 553 as an urging means that is inserted into the hole 50c and arranged so that the end of the other arm urges the guide member 552 toward the abutting member 60. Here, two protrusions 50b are provided at both ends in a direction orthogonal to the document conveyance path, and a rotating shaft 551 and a torsion spring 553 are also provided at both ends correspondingly. On the other hand, the guide member 552 is provided from the front surface to the rear surface in the direction orthogonal to the document conveyance path.

In the present embodiment, the guide member 552 is made of a metal plate (metal plate) such as SUS. Further, the free end side of the guide member 552 extends in the vicinity of the reading position by the CIS 50, specifically, to a position 3 mm upstream from the reading position in the document transport direction. Further, a hemming bent portion 552a is provided on the free end side of the guide member 552, that is, a portion that comes into contact with the document. By providing this folded portion 552a, when contacting with the conveyed document. Generation of paper dust and the like can be prevented. The guide member 552 is made of a metal sheet metal and can be bent by the torsion spring 553, so that the thickness of the conveyed document can be absorbed and even a document with a folding trace can be stabilized. Can be transported.
Further, the torsion spring 553 is made of, for example, a 0.45 mm diameter wire made of SUS304, which is a spring stainless steel material, and biases the guide member 552 toward the conveyance path with a force of 1N. . The urging force by the torsion spring 553 is preferably selected in the range of 1N ± 0.5N. If it is less than 0.5N, the urging force is weakened and the normal general document is out of focus, resulting in a decrease in resolution. On the other hand, if it exceeds 1.5 N, the biasing force is too strong, and for example, a Z-folded thick paper document may be jammed.

  On the other hand, the abutting member 60 is provided on the upstream side in the document conveyance direction, and guides the document to be conveyed. The document conveyance surface 60a guides the document to be conveyed and the document conveyance surface 60a on the downstream side of the document conveyance direction 60a. And a step surface 60b formed by lowering one step. Further, the step surface 60b is formed so as to face the extension line of the light focus point by the SELFOC lens 53, and a white reference tape 64 made of a biaxially stretched polyester film is pasted on the step surface 60b. It is attached. Therefore, the white reference tape 64 is attached to the scanner device 70 via the abutting member 60. In the present embodiment, the white reference tape 64 is disposed with the upper surface exposed in the conveyance path, and the upper surface of the white reference tape 64 is slightly behind the upper surface of the document conveyance surface 60a (away from the conveyance path). Is located on the side). Further, at both ends of the abutting member 60 on the conveyance path side (upper side) and in the direction orthogonal to the document conveyance direction with respect to the white reference tape 64, as shown by the broken lines in the figure, the document is directed toward the document conveyance direction. Ribs 65 are formed as extending gap forming means. The rib 65 is integrally formed of resin together with the abutting member 60, and the height of the rib 65 is appropriately selected from the range of 0.1 to 1.0 mm in consideration of the thickness of the conveyed document. Is set. The height of the rib 65 is preferably slightly larger than the thickness of a document that is frequently used. Then, the guide member 552 urged by the torsion spring 553 contacts the rib 65, so that the document is not transported between the guide member 552 and the document transport surface 60a of the abutting member 60. In this state, a gap of 0.1 to 1.0 mm corresponding to the height of the rib 65 is formed.

  FIG. 3 is a view for explaining the mounting structure of the CIS 50. In FIG. 3, the control member 55 is not shown. As shown in FIG. 3, bolts 56 extending in the same direction as the optical axis of CIS 50 (see FIG. 2) are attached to both side ends (front side, rear side) of CIS 50 (FIG. 3 shows only one side). Shows). A compression spring 57 is wound around the bolt 56, and the bolt 56 is attached to a frame member 58 provided in the document feeder 10 in a state where the compression spring 57 is wound. As a result, the CIS 50 moves toward the side close to the frame member 58 when urged from the conveyance path side (lower side), and also moves away from the frame member 58 when the urge is released. It is possible to move. On the other hand, three protrusions 59 (59a to 59c) are formed in the lower part of the CIS 50, that is, on the side facing the conveyance path, so as to face the white reference tape 64 provided on the abutting member 60.

  Here, FIG. 4A shows a bottom view of the CIS 50 as seen from the conveyance path side, and FIG. 4B shows a top view of the abutting member 60 as seen from the conveyance path side. As shown in FIG. 4A, the protrusion 59 (59a to 59c) provided on the CIS 50 has a length (maximum original width) W in a direction orthogonal to the maximum original conveyance direction that can be read by the image reading apparatus. Of these, the projections 59a and 59b are attached to the rear side of the CIS 50, and the projection 59c is attached to the front side of the CIS 50. Each of these protrusions 59a, 59b, 59c has a half-moon shape. The protrusions 59a, 59b, 59c are formed by integrally molding a resin together with a frame 59d (see also FIG. 3) provided at the lower part of the CIS 50 housing 50a.

  Further, in the abutting member 60, as shown in FIG. 4B, the protrusion 59 provided on the CIS 50 is in contact with the outside of the white reference tape 64 (the contact position is indicated by a broken line in the figure). Indicated by). Further, the white reference tape 64 is affixed corresponding to the maximum document width W. Here, since the protrusions 59a, 59b, and 59c provided on the CIS 50 side have a half-moon shape, they contact the abutting member 60 in a state closer to a line rather than a surface. Become. Further, the rib 65 provided on the abutting member 60 is outside the white reference tape 64 in the direction orthogonal to the document transport direction, and is more than the contact position of the protrusions 59a, 59b, 59c provided on the CIS 50. It is formed inside. The rib 65 is formed by integrally molding a resin together with the abutting member 60. As a result, both ends of the guide member 552 in the direction orthogonal to the document conveyance direction abut against the rib 65, and within the maximum document width W, a predetermined gap is formed between the guide member 552 and the abutting member 60. Will be.

As described above, the document feeder 10 to which the CIS 50 is attached is attached to the scanner device 70 to which the abutting member 60 is attached, so that the document feeder 10 can be opened and closed. In the case of swinging, the protrusions 59a, 59b, 59c provided on the CIS 50 abut against the abutting member 60, and the CIS 50 biased by the compression spring 57 is pressed by the abutting member 60 to form the frame. Retreat toward the member 58 side. That is, the distance between the CIS 50 and the abutting member 60 (and the white reference tape 64) is always kept constant by the compression spring 57 and the protrusions 59a, 59b, and 59c. Thereby, even when the attachment accuracy of the document feeder 10 with respect to the scanner device 70 decreases with the passage of time, the distance between the CIS 50 and the abutting member 60 can be maintained at a constant distance.
Further, when the document feeder 10 is swung in the closing direction with respect to the scanner device 70, the guide member 552 provided on the CIS 50 side contacts the rib 65 provided on the abutting member 60. The guide member 552 urged by the torsion spring 553 is pressed by the rib 65. As a result, the distance between the free end side of the guide member 552 of the control member 55 and the document conveying surface 60a provided on the abutting member 60 is also always kept constant. Here, in the present embodiment, since the rib 65 is formed along the document conveyance direction, the relative relationship between the two when the document feeder 10 is closed with respect to the scanner device 70 with long-term use. Even in the case where the positional relationship is deviated, the gap formed between the two can be kept constant.

  Further, when the document feeder 10 is closed with respect to the scanner device 70, the projection 59 and the abutting member 60 come into contact with each other at three points (projections 59a to 59c). Therefore, it becomes possible to make both contact in a stable state. Further, when the document feeder 10 is opened and closed, the document feeder 10 opens and closes while swinging around the rear support shaft, so that the protrusion 59 opens and closes while sliding with respect to the abutting member 60. It will be. For this reason, it is preferable to use a resin that has low friction and is not easily worn as the material constituting the protrusion 59. Furthermore, the relative positional relationship between the scanner device 70 and the document feeder 10 may be shifted by opening and closing the document feeder 10 with respect to the scanner device 70 a great number of times due to long-term use. However, in the present embodiment, since the rib 65 is formed along the document conveyance direction, the document feeder 10 is closed with respect to the scanner device 70 even if the relationship between the two is slightly deviated. Further, the guide member 552 provided on the document feeder 10 side can be brought into contact with the rib 65 provided on the scanner device 70 side, and the gap between the abutting member 60 and the guide member 552 is constant over a long period of time. Can be maintained.

  Since the CIS 50 employs the SELFOC lens 53 as an optical imaging lens, the depth of focus (field of view) is shallow. FIG. 5 is a diagram for explaining the depth of focus as the lens imaging performance. FIG. 5 shows an MTF (Modulation Transfer Function) having a lens depth (7.87 Lp / mm) using a reduction optical system such as the scanner device 70 according to the present embodiment, and a lens depth using a SELFOC lens 53 ( An example of MTF of 6 Lp / mm) is shown. This “Lp / mm” is a value indicating how many ladder patterns of black and white exist within 1 mm. The MTF expresses how the spatial information (contrast) of a subject is faithfully reproduced from the low frequency range (coarse manuscript) to the high frequency range (fine stripes) using frequency characteristics. . The vertical axis in FIG. 5 indicates MTF (%), and the horizontal axis indicates a state where the distance is 1 mm away from the best focus position on the platen glass or the like, and a state where the distance is 1 mm closer.

  For example, if the target is MTF of 20% or more when reading a document, when the scanner device 70 according to the present embodiment is used, a constant focus is achieved even at about ± 4 mm, and the depth of field can be increased. On the other hand, when the SELFOC lens 53 is used, if the target is MTF of 20% or more, the depth of field is as shallow as about ± 0.3 mm, which is about 1/13 or less than that when the scanner device 70 is used. It is a depth. That is, when reading with the CIS 50 in the present embodiment, it is required to set the reading position of the document within a predetermined narrow range.

  Therefore, in the present embodiment, the control member 55 is provided, and the document is pressed against the abutting member 60 by the control member 55 and conveyed, so that the posture of the document between the platen roll 19 and the out-roll 20 can be stabilized. It was configured to be controllable. 2 and 3 show the movement of the document when the control member 55 is provided. It is understood that the document to be conveyed is conveyed while being pressed against the abutting member 60. In other words, the control member 55 reads the conveyed document while pressed against the abutting member 60, thereby improving the sweetness of the focus when the CIS 50 having a shallow depth of field is used. As described above, the configuration in which the distance between the abutting member 60 and the CIS 50 is constant using the compression spring 57 and the protrusions 59a, 59b, and 59c is also the case where the CIS 50 having a shallow depth of field is used. This is the reason why the sweetness of focus can be improved.

Next, the processing device 80 shown in FIG. 1 will be described.
FIG. 6 is a block diagram for explaining the processing device 80. The processing device 80 to which the present embodiment is applied is large and includes a signal processing unit 81 that processes image information obtained from sensors (CCD image sensor 78 and line sensor 54), a document feeder 10 and a scanner device 70. And a control unit 90 for controlling. The signal processing unit 81 includes an AFE (Analog Front End) 82 that performs analog signal processing, an ADC (Analog to Digital Converter) 83 that converts an analog signal into a digital signal, and various types of shading correction and offset correction for the digital signal. A digital processing unit 84 that performs processing is provided, and the digital signal processed by the digital processing unit 84 is output to a host system, for example, output as image information to a printer.

  On the other hand, the control unit 90 includes an image reading control 91 that controls the entire document feeding device 10 and the scanner device 70, including various double-sided scanning control and single-sided scanning control, a CCD image sensor 78 that is a first sensor, and A CCD / CIS control 92 for controlling the CIS 50, a lamp control 93 for controlling the LED array 52 of the CIS 50 and the illumination lamp 74 of the full rate carriage 73 in accordance with the reading timing, a motor in the scanner device 70 being turned on / off, etc. A scanning control 94 for controlling the scanning operation of the half-rate carriage 75, a motor control in the document feeder 10, various roll operations, a feed clutch operation, a gate switching operation, and the like. It is equipped with a roll 95. From these various controls, control signals are output to the document feeder 10 and the scanner device 70, and these operations can be controlled based on the control signals. The image reading control 91 sets a reading mode based on a control signal from the host system, a sensor output detected in the automatic selection reading function, a selection from the user, and the like, and controls the document feeder 10 and the scanner device 70. I have control.

  Here, in the present embodiment, when an image is read by conveying the document by the document feeder 10, the scanner device 70 (CCD image sensor 78) is used for the document conveyed to the platen roll 19 through the second platen glass 72B. And can be read using the CIS 50 provided in the document feeder 10. However, as described above, the depth of focus differs between reading by the CCD image sensor 78 using the mechanism of the scanner device 70 and reading using the SELFOC lens 53 of the CIS 50, and the resolution characteristics. Will cause a difference. In particular, when a color image such as a photograph is read, color matching becomes difficult when both are read, and the image quality obtained by reading both is different. Therefore, in this embodiment, a plurality of reading modes are prepared, and an optimum mode can be selected based on the setting state of the apparatus, the type of document, the user's selection, and the like.

  FIG. 7 is a flowchart showing an example of processing executed by the image reading control 91 shown in FIG. In the image reading control 91, first, it is determined whether or not the conveyed document is a single-sided document (step 101). This determination is made by, for example, selection from a user using a control panel (not shown) provided on the scanner device 70, or, for example, when the automatic selection reading function is working, the first conveyance before image reading. It can be recognized by sensors (not shown) provided on both sides of the conveyance path on the path 31. In addition, a request from the host system or a selection from the user via a network or the like can be considered. If it is determined in step 101 that the document is a single-sided original, single-sided reading is performed by one pass (one-time original conveyance pass without using a reverse pass) (step 102). In this one-pass single-sided reading, either the reading by the CCD image sensor 78 or the reading by the CIS 50 may be selected. However, in order to realize higher-quality image reading, the reading by the CCD image sensor 78 is selected. It is preferable to do. In such a case, the document tray 11 is placed so that there is a single-sided document portion facing upward and the first page of the document comes up, and the document is transported from the first page and sequentially read.

  If the original is not a single-sided original in step 101, that is, if it is a double-sided original, it is determined whether the original is a white / black original (step 103). The determination in step 103 is determined by the selection from the user or the automatic selection reading function as in step 101. There are cases where the user desires white / black reading even for a color original. When white / black reading is not performed, that is, when color reading is performed, it is determined whether or not image quality is important (step 104). For example, in the case of a color image such as a color photograph or a pamphlet, image quality is generally more important than productivity for increasing the reading speed. Such a determination is also made based on user settings. If it is determined in this step 104 that the image quality is important, double-sided reading by the reverse pass, which is the first double-sided reading mode, is executed (step 105). That is, without reading by the CIS 50, the first surface of the document and the second surface of the document are both read by the CCD image sensor 78 as the first sensor. As a result, both the first side of the original and the second side of the original can be read on both sides with high image quality using the reading means having a deep focal depth.

  On the other hand, when white / black reading is performed in step 103 or when a color image output is required in step 104, for example, when subtle shades such as business colors are not emphasized, plus one color If the image quality is not so important and other factors such as productivity are important, such as in the case of (including other colors such as red and blue in addition to black), the second duplex scanning The mode is simultaneous reading on both sides by one pass without using the reverse pass (step 106). That is, the first surface is read by the CCD image sensor 78 as the first sensor, and the second surface is read by the CIS 50 in the same transport path during this transport path. As a result, it is not necessary to transport the document twice to the same reading unit, the document reading speed can be improved, and the transport path is simplified, so that document transportation troubles such as document jamming (JAM) can be prevented. Can be suppressed. As described above, “simultaneous reading” does not necessarily mean a case in which they coincide with each other in time, and the both sides of the both sides are almost always in one pass without the need for reversing, reversing or re-feeding the document. It means reading at the same time.

  Note that the processing flow shown in FIG. 7 is simplified, and in the case of reading a black and white original in double-sided original reading, double-sided simultaneous reading in step 106 is executed, and in the case of a color original, the reverse path in step 105 is sequentially performed. It is also possible to configure to read a document. Also, these modes can be mixed and used according to the type of document surface.

Next, a document transport method in each document reading mode will be described with reference to FIGS.
FIGS. 8A and 8B are views showing a document pass in the single-sided reading mode by one pass shown in step 102 of FIG. 7 and the double-sided simultaneous reading mode by one pass shown in step 106. FIG. As shown in FIG. 8A, the documents placed on the document tray 11 are sequentially supplied to the first conveyance path 31 by the nudger roll 13, the feed roll 14, the retard roll 15, and the takeaway roll 16. The As shown in FIG. 8B, the supplied document is moved to the second transport path 32 by the transport path switching gate 42 via the reading section of the platen roll 19 and the reading section of the CIS 50, and the discharge tray 40. Are sequentially discharged. In the case of single-sided reading, reading is performed using the CCD image sensor 78 of the scanner device 70 shown in FIG. However, as described above, single-sided reading using the CIS 50 is also possible. In the case of simultaneous reading on both sides by one pass, the first surface is read using the CCD image sensor 78 of the scanner device 70, and the second surface is read using the CIS 50 during the same conveyance. As a result, it is possible to read both sides of the document by one document pass.

  FIGS. 9A to 9D are diagrams for explaining the double-sided reading mode by the reverse path shown in step 105 of FIG. As shown in FIG. 9A, the originals placed on the original tray 11 are sequentially supplied to the first transport path 31 and are used with a platen roll using the CCD image sensor 78 of the scanner device 70 shown in FIG. Reading is performed from below at 19 locations. Then, the transfer path switching gate 42 moves to the fourth transfer path 34 via the third transfer path 33. The document that has completely passed through the third conveyance path 33 is switched back by the inverter roll 22 and the inverter pinch roll 23 and supplied to the fifth conveyance path 35 as shown in FIG. 9B.

  The document supplied to the fifth conveyance path 35 is again supplied to the first conveyance path 31. Then, as shown in FIG. 9C, the document is read from below by the CCD image sensor 78 of the scanner device 70. At this time, the document is in an inverted state from the case shown in FIG. 9A, and the second side that is different from the first side is read. The original on which the second side has been read is in an inverted state. If the original is discharged to the discharge tray 40 as it is, the page order of the loaded original after reading will be out of order. Therefore, as shown in FIG. 9C, the document whose second surface has been read is moved to the fourth transport path 34 via the third transport path 33 using the transport path switching gate 42. The document supplied to the fourth conveyance path 34 and completely passing through the exit switching gate 43 is discharged to the discharge tray 40 by the outlet switching gate 43 via the sixth conveyance path 36 as shown in FIG. Is done. This makes it possible to align the page order of the original after reading in the first double-sided reading mode in which images on both sides of the original are sequentially read.

  In this image reading apparatus, after reading one side (first side) of a document using a CCD image sensor 78 as a first sensor, the document is reversed and the other side (second side) is set to the first side. Using the first double-sided reading mode that is sequentially read by the sensor, and the CIS 50 that is the second sensor provided on the other side facing the first sensor together with the first sensor, A second double-sided reading mode was prepared in which both the front and back sides (first side and second side) of the original were conveyed once. These modes are configured to be selectable automatically or based on a user designation or the like as necessary. This makes it possible to select the duplex scanning mode appropriately and use these modes depending on the application, for example, whether output is monochrome or color, whether speed (productivity) is important, or whether image quality is important. can do.

  In this description, the selection of the reading mode has been described as being executed by the image reading control 91 of the processing apparatus 80. However, these processes are performed by a host that controls the entire image processing apparatus such as a digital color copying machine, for example. It can also be executed by a system or the like.

  Further, in this image reading apparatus, when the shading data on the CIS 50 side is acquired, the following operation is performed before starting the document reading operation. First, the LED array 52 is turned on, and the reflected light from the white reference tape 64 is acquired as reflected data via the SELFOC lens 53 and the line sensor 54. Next, the shading data is generated by the digital processing unit 84 of the processing device 80 based on the acquired reflection data from the white reference tape 64 and stored in a memory (not shown). At the time of actual document reading operation, the image data obtained by reading the document with the CIS 50 is corrected using shading data stored in a memory (not shown), and unevenness caused by the light quantity distribution of the LED array 52 is removed. Then output to the host system. Note that the acquisition of the shading data can be set at an appropriate timing, for example, before the start of a job or for each sheet on which an image is read.

  In order to make the shading data on the CIS 50 side more accurate, it is required that the white reference surface of the white reference tape 64 has no unevenness in the direction orthogonal to the document transport direction. In the initial stage, this requirement can be satisfied by using a white reference tape 64 that is uniformly white. However, as time passes (the number of originals to be read increases), the white reference tape 64 is transferred from dust and originals. As a result, the white reference surface of the white reference tape 64 may become uneven.

  Here, FIG. 10 is a diagram illustrating a state in which the document feeder 10 is lifted and separated (opened) from the scanner device 70 in the image reading apparatus according to the present embodiment. In the present embodiment, as described above, the CIS 50 is mounted on the document feeder 10 and the abutting member 60 is mounted on the scanner device 70, respectively. For this reason, when the document feeder 10 is lifted, the white reference tape 64 mounted on the abutting member 60 is exposed. Therefore, in this image reading apparatus, it is possible to easily wipe off the dirt adhering to the white reference surface of the white reference tape 64, and the maintainability can be improved.

In this image reading apparatus, the CIS 50 is urged by the compression spring 57, and the projection 59 provided on the CIS 50 is pressed against the abutting member 60, thereby positioning the relative position between the CIS 50 and the abutting member 60. Since the distance between the two is kept constant, it is possible to focus even when the CIS 50 has a shallow focal depth when acquiring shading data (when reading the white reference tape 64) and when reading a document. Become.
Further, in the present embodiment, the white reference tape 64 as the white reference member for the CIS 50 is provided not on the document feeder 10 but on the scanner device 70 side, so that the size of the document feeder 10 is reduced accordingly. be able to. Along with this, it is possible to provide a reversal conveyance path and a reversal conveyance mechanism for reversing and conveying a document on the document feeder 10 side.

  As described above, in the image reading apparatus according to the present embodiment, the document is transported to the reading position by the CIS 50 while the document is abutted against the abutting member 60 while the movement trajectory of the document is regulated by the guide member 552. Since it did in this way, the contact with the original document conveyed and the glass 51 provided in CIS50 can be prevented. As a result, it is possible to prevent paper dust, ink, correction fluid, and the like from being transferred and attached from the original to the glass 51, and it is possible to suppress the generation of streaks in the read image data. As a result, the distance between the CIS 50 and the original can be maintained constant, and even when image reading is performed using the CIS 50 having a short focal depth, it is possible to obtain clean image data with no blur.

  In the present embodiment, the abutting member 60 and the guide member 552 are brought into contact with the ribs 65 formed at both ends of the abutting member 60 in the direction orthogonal to the document transport direction. A gap was previously formed between them. Accordingly, it is possible to prevent a situation in which the conveyed document is sandwiched between the abutting member 60 and the guide member 552 and the document is clogged. Further, in the double-sided simultaneous reading mode using one pass described above, it is possible to prevent a situation in which the leading edge of the document is caught between the abutting member 60 and the guide member 552 and the speed of the document is changed. Thereby, the situation where the image read by the CCD image sensor 78 is disturbed does not occur.

Furthermore, in the present embodiment, since the guide member 552 is made of a metal sheet metal, the guide member 552 is less likely to be deformed than when a plastic film or the like is used, for example. Can be maintained. In the present embodiment, since the guide member 552 is exposed by lifting the document feeder 10 and can be contacted by the user, it is effective to use a sheet metal that can be easily prevented from being deformed by the user's contact. is there.
In this embodiment, by forming the folded portion 552a that is hemmed and bent on the free end side of the guide member 552 that comes into contact with the document, the conveyed document and the guide member 552 come into contact with each other. The amount of paper dust generated can be reduced. As a result, the influence of paper dust on the image data read by the CIS 50 can be removed, and good image data can be obtained.

It is the figure which showed the image reading apparatus with which this Embodiment is applied. It is a figure for demonstrating the reading structure using CIS. It is a figure for demonstrating the attachment structure of CIS. (a) is the bottom view of CIS seen from the conveyance path side, (b) is the top view of the abutting member seen from the conveyance path side. It is a figure for demonstrating a depth of focus as lens imaging performance. It is a block diagram for demonstrating a processing apparatus. It is the flowchart which showed an example of the process performed by image reading control. (a), (b) is a figure for demonstrating the original path | pass of the 2nd double-sided reading mode which is the single-sided reading mode by 1 pass, and the double-sided simultaneous reading by 1 pass. (a)-(d) is a figure for demonstrating the double-sided reading by a reverse path | pass. It is a figure which shows the state which lifted the original document feeder from the scanner apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Document feeder, 11 ... Document tray, 19 ... Platen roll, 20 ... Out roll, 31 ... 1st conveyance path, 32 ... 2nd conveyance path, 33 ... 3rd conveyance path, 34 ... 4th conveyance path, 35 ... Fifth transport path, 36 ... Sixth transport path, 40 ... Discharge tray, 50 ... CIS (Contact Image Sensor), 50a ... Housing, 51 ... Glass, 52 ... LED (Light Emitting Diode) array, 53 ... Selfoc lens 54 ... Line sensor, 55 ... Control member, 552a ... Folding part, 56 ... Bolt, 57 ... Compression spring, 58 ... Frame member, 59 ... Protrusion, 60 ... Abutting member, 60a ... Original conveying surface, 60b ... Step surface , 61 ... Guide, 62 ... Garbage reservoir, 63 ... Opening, 64 ... White reference tape, 70 ... Scanner device, 71 ... Device frame, 72A ... First platen glass, 72B ... Second platen glass, 7 ... Full-rate carriage, 74 ... Illumination lamp, 75 ... Half-rate carriage, 76A ... First mirror, 76B ... Second mirror, 76C ... Third mirror, 77 ... Imaging lens, 78 ... CCD image sensor, 80 ... Processing device , 81 ... signal processing unit, 90 ... control unit

Claims (10)

A transport path through which the document is transported;
A CIS (Contact Image Sensor) that is provided on one side of the conveyance path and reads an image of a document conveyed along the conveyance path ;
An opposing member provided on the other side of the transport path and disposed opposite the CIS across the transport path ;
One side of the conveyance path, which is provided on the upstream side of the CIS in the document conveyance direction, is configured by a metal plate having flexibility, and the document conveyed on the conveyance path serves as the counter member . A guide member that guides the document to be abutted,
It is provided on the other side of the conveyance path so as to protrude from the outer side of both ends in the direction orthogonal to the conveyance direction of the maximum size document conveyed on the conveyance path, with the conveyance path interposed therebetween. An image reading apparatus comprising: a gap forming member that forms a gap for allowing a document to pass between the facing member and the guide member by abutting the opposing guide member . The guide member is attached so that the upstream side in the transport direction of the document is a fixed end and the downstream side in the transport direction is a free end with respect to the CIS , and the end on the free end side is the side in contact with the gap forming member. The image reading apparatus according to claim 1, wherein the image reading apparatus is bent to the opposite side . The fixed end side of the guide member is attached to the CIS,
The image according to claim 2, further comprising a biasing member that biases the CIS toward the opposing member and biases the guide member toward the gap forming member via the CIS. Reading device. The image reading apparatus according to claim 3, further comprising a spring attached to the CIS and imparting to the guide member a force in which a free end side of the guide member is directed toward the gap forming member. The gap forming members are respectively provided outside both ends in a direction orthogonal to the conveyance direction of the maximum-size document conveyed on the conveyance path, and each is formed along the document conveyance direction. The image reading apparatus according to claim 1. A transport path through which the document is transported;
A first reading unit that reads a first surface of a document from one side of the conveyance path;
A second reading unit that is configured by a CIS (Contact Image Sensor), is provided downstream of the first reading unit in the document conveyance direction, and reads an image on the second surface of the document from the other side of the conveyance path. When,
A counter member provided on the other side of the transport path and disposed to face the second reading unit across the transport path ;
On one side of the transport path, downstream of the document reading direction with respect to the first surface reading position by the first reading unit and at the second surface reading position of the second surface by the second reading unit. A guide member that is provided on the upstream side in the transport direction and is configured of a flexible metal plate , and guides the document so that the document transported along the transport path is abutted against the opposing member ;
The other side of the conveyance path is provided to protrude from the outer side of both ends in the direction orthogonal to the conveyance direction of the maximum size document conveyed on the conveyance path, and sandwiches the conveyance path. An image reading apparatus comprising: a gap forming member that forms a gap for allowing a document to pass between the facing member and the guide member when the guide members facing each other are abutted against each other . The guide member is attached so that the upstream side in the transport direction of the document is a fixed end and the downstream side in the transport direction is a free end with respect to the second reading portion, and the end on the free end side is connected to the gap forming member. The image reading apparatus according to claim 6, wherein the image reading apparatus is bent to a side opposite to the side in contact with the side. The fixed end side of the guide member is attached to the second reading unit,
It further includes an urging member that urges the second reading portion toward the facing member and urges the guide member toward the gap forming member via the second reading portion. The image reading apparatus according to claim 7. The image reading apparatus according to claim 8, further comprising a spring attached to the second reading unit, the spring applying a force toward the guide member at a free end side of the guide member toward the gap forming member. The gap forming members are respectively provided outside both ends in a direction orthogonal to the conveyance direction of the maximum-size document conveyed on the conveyance path, and each is formed along the document conveyance direction. The image reading apparatus according to claim 6.

Images