JP2008148265A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of obtaining excellent picture quality well balanced between top and reverse sides without troubling a user to perform operation by switching the image reader to a read mode suitable to resolution or picture quality to be required when a document image is read. <P>SOLUTION: Images of both sides of the document M conveyed by a document conveying means 100 are read by switching the image reader between a first read mode wherein the images of both sides of the document M by first and second read means 318 and 320 and a second read mode wherein only one of the first or the second read means is used with the document being turned over on an inversion path 110 on the basis of at least one of the resolution or picture quality requested when images of a document M are read. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention has a sheet-through type automatic document feeder and is applied to a copying machine, a facsimile machine, an MFP (Multi Function Peripherals), etc., and can read an image on one side / both sides of a document. About.

  Conventionally, in this type of image reading apparatus, an original is transported to a reading area where a platen glass is arranged, an image on one side of the original is read, the original discharged from the original is reversed by a reverse path, and again In some cases, an image on the other side of the document is read by being conveyed to the reading area.

  In addition, a first reading unit that reads an image on one side of the document is arranged on one side of the reading area across the conveyance path, and a second reading unit that reads an image on the other side of the document on the other side. In addition to double-sided reading by reversing the original, it is also known that the first and second reading units can simultaneously read images on both sides of the original (for example, patents) Reference 1).

  In this case, in addition to the simultaneous reading of both sides of the document, depending on the type of paper, only the image on one side of the document can be read using the reversal path.

In addition to these, depending on the thickness of the document, for example, when the thickness of the document is a predetermined value or less, the first and second reading units do not read both sides of the document simultaneously, A technique is known in which one reading unit executes a mode in which both sides are read one by one (see, for example, Patent Document 2).
JP 2004-15299 A JP 2003-43866 A

  By the way, with the spread of color machines, for example, recently, demands for the quality of read images have increased.

  However, in the mode in which the image on one side of the document and the image on the other side of the document are simultaneously read by the conventional first and second reading units, the first and second images are scanned for images that require high image quality such as photographs. There may be a slight difference in hue between the reading unit and the second reading unit, and some users may not be satisfied with the difference.

  As a countermeasure, for example, the reading unit is manually switched so that the image on one side and the image on the other side of the document can be read by only one reading unit, or both sides of the document are switched manually. Although these are conceivable, both of them are troublesome for the user and impair the operability.

  Further, as in the technique described in Patent Document 2, when the original thickness is equal to or less than a predetermined value, the original is read one side at a time by one reading unit. Although it may be possible to prevent the show-through due to the light of the reading unit, even if the user does not want high image quality or high resolution, simultaneous reading of both sides of the document by the first and second reading units is not possible. There is a problem that it is difficult to meet image quality and resolution level requirements.

  The present invention switches to a reading mode suitable for the resolution or image quality required at the time of reading a document image, and can obtain a good image quality that is balanced between the front and back sides without requiring user's operation. An object is to provide an apparatus.

The above problem is solved by the following means.
(1) A document transporting means capable of transporting a document so that the document is transported from a paper feed tray to a reading region, re-conveyed to the reading region in a state of being reversed by a reversing path, and transported to the reading region. A first reading unit that reads an image on one side of the original, and an image on the other side of the original that is arranged with respect to the first reading unit across the original conveyance path and is conveyed to the reading area. Based on at least one of second reading means capable of reading simultaneously with reading by the first reading means and resolution or image quality required at the time of reading the original image, the original conveying means The first reading mode for reading the images on both sides of the original conveyed by the first and second reading means and the images on both sides of the original for the first time. Includes a control unit that uses only one of the second reading units and switches between a second reading mode in which the document is reversed by the reversing path and reads the images on both sides of the document. An image reading apparatus.
(2) When the resolution or image quality required at the time of reading the document image is high resolution or high image quality, the control means switches to the second reading mode, and the resolution or image quality is low resolution or low image quality. The image reading apparatus according to item 1, wherein the first reading mode is switched to.
(3) The image reading apparatus according to item 1 or 2, wherein it is possible to set whether the switching of the reading mode is enabled or disabled.
(4) Document thickness detecting means for detecting the thickness of the document is provided, and the control means is configured to perform a first reading mode based on the document thickness detected by the detecting means and the resolution or image quality level. 2. The image reading apparatus according to item 1, wherein the image reading apparatus and the second reading mode are switched.

  According to the invention described in item (1) above, when the document fed out from the paper feed tray is carried into the reading area, the image on one side of the document is read by the first reading means, and further the second The image on the other side of the document is read by the reading means. That is, in the first reading mode in which the first and second reading units operate, the images on both sides of the document are read simultaneously by a single sheet passing.

  In the second reading mode in which only one of the first and second reading means is used, an image on one side of the original is read, then the original is inverted, and the other side of the inverted original is read. The image is read.

  Since the first reading mode and the second reading mode are switched based on at least one of resolution and image quality required at the time of reading a document image, for example, a request for high image quality or high resolution is required. If so, it is possible to solve the problem that the reading image quality of the other side is inferior to the reading image quality of the one side of the document by switching to the reading mode corresponding thereto.

  According to the invention described in the above item (2), when the resolution or image quality required at the time of reading the document image is high resolution or high image quality, the second reading mode is switched. The image on both sides of the document can be read using only the image, and the difference in the color of the read image on both sides of the document can be eliminated to satisfy the user. In addition, when the resolution or image quality required when reading the document image is low resolution or low image quality, the mode is switched to the first reading mode, and the images on both sides of the document are displayed using the first and second reading means. Since it is read simultaneously, it can contribute to the improvement of productivity.

  According to the invention described in (3) above, it is possible to set whether to enable or disable the switching of the reading mode. For example, when improvement in productivity is more important than image quality and resolution. In such a case, an operation for invalidating the switching and fixing to the first reading mode is also possible.

  According to the invention described in item (4) above, since the reading mode of the double-sided image of the document can be switched depending on the combination of the thickness of the document, the image quality, and the resolution level, it becomes possible to respond to a finer image quality requirement. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an image reading apparatus according to an embodiment of the present invention.

  In FIG. 1, the image reading apparatus includes a sheet-through type automatic document feeder (ADF) 101 that reads an image while conveying a document, a scanner unit 103, a control unit 313 (FIG. 3), and an operation panel 400. Etc.

  The ADF 101 includes a paper feed tray 200 and a document transport unit 100.

  The paper feed tray 200 is for placing the document M so that it can be fed out.

  The document conveying unit 100 includes a sheet feeding roller 220 that pulls out the document M from the sheet feeding tray 200, a separation roller 221 that separates the document M from the sheet feeding tray 200, and a front roller that is located upstream of the first reading area S1. 201 and a post-reading roller 202 positioned downstream of the reading area S1, and after reading a single-sided image of the document M, the document M is once discharged and then switched back by the switchback roller 111. Thus, the reversing path 110 is provided to be directed to the first reading area S1 in the reversed state.

  The ADF 101 controls document feeding and conveying operations by the CPU 300 (FIG. 3).

  In a predetermined part of the transport path, there are a first reading unit 318 provided corresponding to the first reading area S1, and a second reading area S2 located slightly downstream of the first reading area S1. Correspondingly provided second reading units 320 are arranged across the document conveyance path.

  The scanner unit 103 includes a first reading unit 318 and a first image processing unit 319 (shown in FIG. 3).

  The first reading unit 318 passes through the platen glass 205 and exposes the original M that has reached the first reading area S1, the light source reflector 208, and the reflected light from the original M. A plurality of mirrors 209 facing the CCD 213 and a lens 211 interposed between the mirror 209 and the CCD 213 are provided.

  The analog signal from the CCD 213 is converted into a digital signal by the A / D converter 12 and then subjected to predetermined image processing by the first image processor 319 (FIG. 3).

  The second reading unit 320 provided on the ADF 101 side is composed of a contact image sensor (CIS) and has substantially the same function as the first reading unit 318, and is shown in FIG. As described above, a pair of LEDs 320a and 320b that irradiate light to the original M that has reached the second reading area S2 through the glass 320c, a Selfoc lens 320d that condenses the reflected light from the original M, and condensing light. A line sensor 320e for receiving the reflected light is provided. Here, a CCD is used as the line sensor 320e, but other light receiving elements such as a C-MOS sensor can be used.

  The analog signal from the CCD line sensor 320e is converted into a digital signal by the A / D converter (FIG. 4) 22, and then subjected to predetermined image processing by the second image processor 321 (FIG. 3). It has become so.

  The control unit 313 includes the scanner CPU and controls the scanner unit 103. For example, the level of image quality and resolution required when reading a document image is determined, and the conveyance of the document M by the conveyance unit 100, the reading operations by the first and second reading units 318 and 320, and the like are controlled. Specific control will be described later.

  The operation panel 400 is used for a user to input various operations and processing modes, and to display the status and messages of the apparatus, and includes a touch panel type display unit 401. Also, the administrator or the like can set a setting for enabling or disabling switching between a first reading mode and a second reading mode, which will be described later, and a setting for image quality and resolution level at the time of document reading, via the operation panel. It is supposed to be able to do. These settings are accepted by the control unit 313.

  In such an image reading apparatus, the original M stacked on the paper feed tray 200 is fed by the paper feed roller 220 and conveyed to the first reading area S1 by the separation roller 221 and the pre-reading roller 201.

  In the scanner unit 103, an image on one side of the original M passing through the first reading area S <b> 1 is exposed by the exposure device 206 in the first reading unit 318, and reflected light from one side of the original M is scanned. Is received by the CCD 213 through the platen glass 205 and the lens 211. Based on the RGB data from the CCD 213, the first image processing unit 319 generates image data.

  When the document M that has passed through the first reading area S1 passes through the second reading area S2, the second reading unit 320 reads an image on the other side of the document M and generates image data.

  After passing through the second reading area S <b> 2, the document M is conveyed to the right in FIG. 1 by the post-reading roller 202 and is discharged to the discharge tray 222.

  In this way, the document M is transported from the paper feed tray 200 to the first and second reading areas S1 and S2 and discharged to the discharge tray 222 without being re-transported to the reading area. Is conveyed, the image on one side of the document M is read by the first reading unit 318 and the other image is read by the second reading unit 320 (first reading mode). That is, the images on both sides of the document M can be read simultaneously with a single sheet passing.

  In the first reading area S1, a conveyance guide member 215 is disposed on the platen glass 205 so that the document M carried into the first reading area S1 is conveyed without contact with the platen glass 205. To guide.

  The post-reading roller 202 pulls the original M at a slightly higher speed than the pre-reading roller 201, and prevents the original M from coming into contact with the platen glass 205 due to slack.

  By the way, if there is a foreign substance such as paper dust or adhesive on the platen glass 205, it will remain in the reading area S1, and if one side of the original M is read as it is, the presence of the foreign substance will be conveyed by the original. Appears in image data as color streak noise along the direction. For this reason, as described above, by taking measures to prevent the original M from coming into contact with the platen glass 205, intrusion of foreign matter on the platen glass 205 due to the contact between the original M and the platen glass 205 is mainly suppressed.

  Further, in this embodiment, when a high image quality or a high resolution is required when reading a double-sided image of the document M, the control unit 313 causes the first reading unit 318 and the second reading unit 320 to The reading mode (second reading mode) for reading the images on both sides of the document M using only one reading unit is switched. In this case, the transport path of the original M is also a state in which the original is transported from the paper feed tray 200 to the reading area of one reading unit, switched back by the switchback roller 111 in the middle of discharge, and reversed by the reverse path 110. Then, the second document transport path is switched to the second document transport path for discharging after re-transporting to the same reading area as described above.

  Although not shown, the paper feed tray 200 of the ADF 101 has a guide member for preventing tilting at the time of paper feed, and a position detection sensor connected to the guide member and a feed direction of the paper feed tray 200 are provided. The size of the document M on the sheet feed tray 200 can be determined by the combination with the plurality of document detection members.

  A document thickness detection sensor 304 (shown in FIG. 3) is disposed on the document transport path to detect the thickness of the fed document M and whether the detected value is equal to or smaller than a predetermined value. It is configured to determine whether or not. For the detection of the thickness of the document M, various methods using, for example, transmitted light or ultrasonic waves can be employed.

  FIG. 3 is a block diagram showing a control system for controlling a document image reading operation by the image reading apparatus.

  In FIG. 3, a CPU 300 that controls the ADF 101 is communicably connected to a scanner CPU 313 that controls the scanner unit 103. Through this communication, the CPU 300 reads the size information and operation mode of the document M, and further reads the document M. Various control information such as timing information is exchanged.

  To the CPU 300 of the ADF 101, drive ICs 301, 302, and 303 that drive the drive pulse motors 231, 232, and 233, respectively, are connected.

  The CPU 300 controls driving by inputting excitation signals of φ0 to φ3 to the drive pulse motors 231, 232, and 233, and changes the document conveyance speed according to the magnification and the mode, thereby conveying the document. It comes to control.

  The drive pulse motors 231, 232, and 233 individually drive the paper feeding unit / reading unit / discharge unit and the like in the ADF 101, and change the speed and rotation direction according to the conveyance timing of the document M. By switching, the document M can be passed.

  Further, the analog port of the CPU 300 is connected to a sensor 304 that detects excessive light of the document M and determines its thickness as a thickness detection unit of the document M, and a predetermined reference value and sensor output voltage are determined. Is compared to determine whether or not the thickness of the document M is equal to or less than a predetermined value.

  The first reading unit 318 is controlled by the scanner CPU 313. The CPU 313 controls the drive motor 315 so as to move the reading slider unit 210 including the exposure device 206, the reflection plate 208, and the mirror 209 to the reading position S1.

  Image data from the CCD 213 in the first reading unit 318 is input to the scanner CPU 313 via the first image processing unit 319 and sent to an image data output unit (not shown).

  The second reading unit 320 is mounted on the ADF 101. Image data from the line sensor 320 e in the second reading unit 320 is input to the scanner CPU 313 via the second image processing unit 321.

  Regarding the switching of the operation (reading mode) between the first image reading unit 318 and the second image reading unit 320, the ADF CPU 300 communicates with the scanner CPU 313, whereby the first reading unit 318 and the second reading unit 318. This is performed by recognizing which mode of the unit 320 is used.

  FIG. 4 is a block diagram showing an electrical configuration of the first and second image processing units 319 and 321.

  In FIG. 4, an image signal read by the CCD 213 in the first reading unit 318 is input to the A / D conversion unit 12 and converted into a digital signal.

  The digital image signal is then processed by a shading correction unit 13 and a lightness / color separation unit 14 for converting colors into lightness and color difference methods. Further, adjustment processing is performed by the sharpness adjustment unit 15, the HVC adjustment unit 16, and the density correction unit 18 for image sharpening. Thereafter, the image is processed by a color space conversion unit 17 that converts the color space of the image into an L * a * b * color space, and a compression / expansion unit 19 for compressing and storing the data. The image data is temporarily stored in the data storage memory unit 20 through the compression / decompression unit 19.

  The sharpness adjusting unit 15 and the HVC adjusting unit 16 can optimize the read image by setting image parameters for adjusting image density and the like.

  Also, the second image processing unit 321 has the same image processing configuration as the first image processing unit 319. That is, the image signal read by the CCD 320e, which is a line sensor in the second reading unit 320, is input to the A / D conversion unit 22 and converted into a digital signal.

  Next, the digital image signal is processed by the shading correction unit 23 and the lightness / color separation unit 24. Further, adjustment processing is performed by the sharpness adjusting unit 25, the HVC adjusting unit 26, and the density correcting unit 18 for image sharpening. Thereafter, the image is processed by a color space conversion unit 27 that converts the color space of the image into an L * a * b * color space, and a compression / expansion unit 29 that compresses and stores the data. The image data is temporarily stored in the data storage memory unit 20 via the compression / decompression unit 29.

  In the first image processing unit 319, an optimum image parameter is set by the image adjustment parameter setting unit 41 for the sharpness adjustment unit 15, the HVC adjustment unit 16, and the density correction unit 18, and the first In the second image processing unit 321, optimal image parameters are set by the image adjustment parameter setting unit 42 for the sharpness adjustment unit 25, the HVC adjustment unit 26, and the density correction unit 28.

  FIG. 5 is an explanatory diagram of a document conveyance path corresponding to each reading mode of a document image.

  FIG. 5A shows the case of the first reading mode, that is, the simultaneous reading mode in which the first and second reading units 318 and 320 simultaneously read the images on both the front and back sides of the document M. The document M is transported along the first document transport path.

  That is, the document M fed from the paper feed tray 200 is passed through the first reading area S1 by the transport unit 100. The original M is conveyed along a path indicated by a solid line a, and when the first reading area S1 is reached, the front image of the original M is read by the first reading unit 318. On the other hand, when the original M reaches the second reading area S <b> 2, the back side image of the original M is read by the second reading unit 320 and then discharged onto the paper discharge tray 222. That is, the images on both the front and back sides of the document M can be simultaneously read by one paper passing.

  In the single-sided reading mode in which the first reading unit 318 reads an image on one side (for example, the front side) of the document M, it is conveyed along the same path as described above.

  FIG. 5B shows the second reading mode, in other words, using either one of the first reading unit 318 and the second reading unit 320 to read the surface of the document M, and then the document. This shows the case of the reverse reading mode in which the reverse side is read using the same reading unit as the front side in the inverted state, and the original M is conveyed along the second original conveying path.

  That is, when double-sided reading is performed by the first reading unit 318, the document M fed from the paper feed tray 200 is conveyed to the first reading region S1 as indicated by the solid line a, and the document M is transferred to the first reading region. When S1 is reached, the first reading unit 318 reads the surface image of the document M. After that, when the document M is conveyed in the direction indicated by the solid line b by the switchback roller 111 and reversed by the reversing path 110 and then again passes through the first reading region S1, the first reading unit 318 The back image of the original M is read.

  When the reading of the images on both the front and back sides of the document M is completed, the document M is transported in the direction indicated by the solid line c, so that the document M is reversed again and discharged to the discharge tray 222 in a state where the page order is aligned.

  On the other hand, when duplex scanning is performed by the second scanning unit 320, the document M is transported along the same transport path, but the other surface of the document M, that is, the back surface image is scanned, and then the front surface image is scanned. Is done. Finally, the page order on the image is changed by an image control unit (not shown).

  Next, switching control processing between the first and second reading modes executed by the image reading apparatus shown in FIGS. 1 to 4 will be described based on the flowchart of FIG. In this embodiment, the front surface (first surface) of the document is read by the first reading unit 318, and the back surface (second surface) of the document is read by the second reading unit 318 in the first reading mode. In the second reading mode, the original is turned upside down and read by the first reading unit 318. Of course, in the second reading mode, only the second reading unit 320 may be used to read both sides of the document.

  In FIG. 6, in step S1, it is determined whether or not the original M is in the double-sided reading mode. If the original M is not in the double-sided reading mode (NO in step S1), the process ends. If it is the duplex reading mode of the document M (YES in step S1), it is determined in step S2 whether or not the automatic switching control of the first / second reading units 318 and 320 is set to be effective. If the automatic switching control is invalid (NO in step S2), the process proceeds to step S6.

  Specifically, this is the case when a user who wants to focus on productivity rather than image quality has set automatic switching of the reading mode to “invalid” by a user setting mode or the like by input from the operation panel 400. Equivalent to.

  If the automatic switching control is valid (YES in step S2), it is determined in step S3 whether the image quality mode or the high resolution mode is set.

  Here, as a determination criterion for the high image quality mode or the high resolution mode, the high image quality mode or the high resolution mode may be set in advance, or the user may set the high image quality mode or the high resolution mode from the operation panel 400. May be. Or you may judge based on the input of the processing mode by a user. For example, the user designates a photo mode to perform copying, or the user designates a high resolution mode to perform scanning.

  If the mode is the high image quality mode or the high resolution mode (YES in step S3), in step S4, the simultaneous reading mode (first reading mode) using the first and second reading units 318 and 320 is canceled, and the first After switching to the reverse reading mode (second reading mode) in which the reading unit 318 reads the back side of the document, this processing is terminated. As a result, since the images on both the front and back sides of the document M are read only by the first reading unit 318, the inconvenience of causing a slight difference in color between the front and back is eliminated.

  If it is not the high image quality mode or the high resolution mode (NO in step S3), in step S5, the mode is switched to the simultaneous reading mode, and the first and second reading units 318 and 320 simultaneously apply to both-side images of the document M. Reads automatically. Thereby, both sides of the original M can be read with high production efficiency.

  On the other hand, when it is determined in step S2 that the automatic switching control is invalid (NO in step S2), in step S6, it is determined whether or not to read the back side of the document M using the second reading unit (that is, Judgment of reverse reading mode or simultaneous reading mode).

  This determination is made based on, for example, whether the user is fixing to the simultaneous reading mode that emphasizes productivity, or is fixed to the reverse reading mode with emphasis on image quality, based on input from the operation panel 400 or the like. .

  If it is fixed to the simultaneous reading mode (YES in step S6), in step S7, the mode is switched to the simultaneous reading mode in which the second reading unit 320 is also used. If it is the reverse reading mode (NO in step S6), in step S8, the image reading on the back side of the original M is switched to the reverse reading mode performed by the first reading device 318 by inverting the original.

  Next, another example of the first and second reading mode switching control processing executed by the image reading apparatus shown in FIGS. 1 to 4 will be described with reference to the flowchart of FIG. Also in this example, it is assumed that the front surface (first surface) of the document is read by the first reading unit 318.

  In FIG. 7, in step S10, it is determined whether or not the original M is in the double-sided reading mode. If the original M is not in the double-sided reading mode (NO in step S10), the process ends. If it is the duplex reading mode of the document M (YES in step S10), it is determined in step S11 whether or not automatic switching control of the first / second reading units 318 and 320 is valid.

  If the automatic switching control is invalid (NO in step S11), the process proceeds to step S17.

  In this case as well, specifically, when a user who wants to place more emphasis on productivity than image quality has set automatic switching of the reading mode to “invalid” by a user setting mode or the like by an input from the operation panel 400, etc. It corresponds to.

  If the automatic switching control is valid (YES in step S11), in step S12, the signal of the original thickness detection sensor 304 determines whether the paper thickness of the original M is equal to or less than a predetermined value (paper thickness ≦ α). If the paper thickness is equal to or smaller than the predetermined value (paper thickness ≦ α) (YES in step S12), the image quality / resolution mode is “level 2” or higher (image quality / resolution ≧ “level 2”) in step S13. ) Or not.

  The level of the image quality mode is determined in advance based on image quality, resolution, and the like. Here, for example, “level 1” has the highest image quality requirement, and “level 2”, “level 3”,. Accordingly, the image quality requirement level is set to be lowered.

  The image quality request is input by the user selecting from a plurality of reference values via the operation panel 400.

  If the image quality / resolution mode is higher than “level 2” (YES in step S13), in step S14, the simultaneous reading mode is canceled, the original M is reversed, and then read by the first reading unit 318. Switch to reverse reading mode.

  If the image quality / resolution mode is lower than “level 2” (image quality / resolution <“level 2”) (NO in step S13), in step S16, the simultaneous reading mode using the second reading unit 320 is used. And both sides of the original M are read simultaneously.

  If the paper thickness exceeds a predetermined value (paper thickness> α) (NO in step S12), whether the image quality / resolution mode is “level 1” or higher (image quality / resolution ≧ “level 1”) in step S15. Judge whether or not.

  If the image quality / resolution mode is “level 1” or higher (image quality / resolution ≧ “level 1”) (YES in step S15), the process proceeds to step S14 to switch to the reverse mode.

  If the image quality / resolution mode is a low level less than “level 1” (image quality / resolution <“level 1”) (NO in step S13), in step S16, the above-described simultaneous reading mode is refinanced.

  The switching of the reading mode according to the paper thickness of the original M in this way takes into account the influence light from the first reading unit 318 due to the thickness of the original M. Specifically, when the document M is thin paper, the image quality is improved by selecting the reverse reading mode using the reverse path 110 even if the image quality is lower.

  If it is determined in step S11 that the automatic switching control is invalid (NO in step S11), in step S17, whether or not reading of the back side of the document M is performed using the second reading unit (that is, inversion). Read mode or simultaneous read mode).

  This determination is made based on, for example, whether the user is fixing to the simultaneous reading mode that emphasizes productivity, or is fixed to the reverse reading mode with emphasis on image quality, based on input from the operation panel 400 or the like. .

  If it is fixed to the simultaneous reading mode (YES in step S17), in step S18, the mode is switched to the simultaneous reading mode in which the second reading unit 320 is also used. If it is the reverse reading mode (NO in step S17), in step S19, the image reading on the back side of the original M is switched to the reverse reading mode performed by the first reading device 318 by inverting the original.

  As described above, in the embodiment shown in FIG. 7, since the reading mode is switched based on the combination of the detected thickness of the document M and the image quality / resolution level, it is possible to easily cope with a finer image quality requirement.

1 is a schematic configuration diagram illustrating an image reading apparatus according to an embodiment of the present invention. It is a schematic block diagram which similarly shows an example of the 2nd reading part in an image reading apparatus. 3 is a block diagram showing a control system for controlling a document image reading operation by the image reading apparatus. FIG. It is a block diagram which shows the electric constitution of the image processing part corresponding to the 1st and 2nd reading part, respectively. FIG. 6 is an explanatory diagram of a document conveyance path in each document image reading mode. 10 is a flowchart showing a reading mode switching control process when reading an image on the back side (second side) of a document. 10 is a flowchart illustrating another example of reading mode switching control processing when reading an image on the back side (second side) of a document.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Conveyance part 110 Reverse path 101 Automatic document conveying apparatus 200 Paper feed tray 304 Document thickness detection part 313 Control part 318 1st reading part 320 2nd reading part M Original S1 1st reading area S2 2nd reading area

Claims (4)

A document transporting means capable of transporting a document so that the document is transported from a paper feed tray to a reading region, and is transported again after being transported to the reading region in a state of being reversed by a reversing path;
First reading means for reading an image on one side of the document conveyed to the reading area;
An image of the other side of the document that is arranged with respect to the first reading unit with the document conveyance path interposed therebetween can be read simultaneously with the reading of the first reading unit. A second reading means;
Based on at least one of resolution and image quality required at the time of reading the original image, the first and second reading means read the images on both sides of the original conveyed by the original conveying means. And a second reading mode in which images on both sides of the document are read by using only one of the first or second reading means and inverting the document through the reversing path. Control means for reading images on both sides of
An image reading apparatus comprising:   When the resolution or image quality required at the time of reading the document image is high resolution or high image quality, the control means switches to the second reading mode, and when it is low resolution or low image quality, The image reading apparatus according to claim 1, wherein the image reading apparatus is switched to one reading mode.   The image reading apparatus according to claim 1, wherein whether the switching of the reading mode is enabled or disabled can be set. A document thickness detecting means for detecting the thickness of the document;
The image reading apparatus according to claim 1, wherein the control unit switches between the first reading mode and the second reading mode based on the thickness of the document detected by the detecting unit and the level of the resolution or image quality. .

Images