JP5321518B2 - Image reading apparatus and document conveying method in image reading apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and a document conveying method in the image reading apparatus, and more particularly to a sheet-through type image reading apparatus that automatically conveys a document to a reading position and a document conveying method in the image reading apparatus.

  A conventional image reading apparatus includes a plurality of roller pairs sandwiching a conveyance path, and conveys a document to a reading position in the conveyance path by rotation of the plurality of roller pairs. The document is transported by rotation of the roller pair at each position, at least two places being restrained by the upstream roller pair and the downstream roller pair in the transport direction.

  In such an image reading apparatus, since it is conveyed by being restrained at least two places, a load is applied to the conveyed document due to the difference in rotational speed between the adjacent upstream roller pair and the downstream roller pair. Or an inclination (skew) occurs in the transport path. The load or skew applied to the document at the reading position leads to deterioration of the quality of the read image.

  For example, in Japanese Patent Laid-Open No. 2001-60023 (hereinafter referred to as Patent Document 1), the rotation speed of the fixing conveyance roller changes due to heating, thereby causing a difference between the rotation speed of the downstream roller and the roller pair. The problem of generating a load on the conveyed paper is cited. In order to solve this problem, Patent Document 1 adjusts the rotation speed of these roller pairs to form a loop (slack) in the document in the conveyance path between the fixing conveyance roller and the downstream roller, thereby reducing the sheet. The technology which buffers the force which acts on is proposed.

  Japanese Patent Laid-Open No. 2003-34450 (hereinafter referred to as Patent Document 2) prevents the quality of a read image from being deteriorated by vibration generated when the trailing edge of the document passes through a roller pair immediately before the reading position. A technique for separating the roller pair before the rear end passes is proposed.

Japanese Patent Laid-Open No. 2001-60023 JP 2003-34450 A

  With respect to the document conveyed in the conveyance path, the upstream roller pair and the adjacent downstream roller pair are stopped by stopping the rotation of the roller pair at the timing when the leading edge of the document reaches the upstream roller pair. In the conveyance path between the two, a similar loop can be formed with the position of the upstream roller pair as the head. This loop is eliminated by resuming the rotation of the upstream roller pair.

  Such a loop is once formed on the upstream side of the reading position and then eliminated, whereby the inclination (skew) of the document in the conveyance path can be corrected. In addition, once such a loop is formed immediately before the reading position, the loop is canceled and conveyed to the reading position, thereby reducing the load on the document during reading and improving the quality of the read image. Connected.

  However, there is a problem that even if the method of once forming a loop and transporting the document to the reading position is used in this way, the read image may be disturbed. In particular, the inventors of the present application have found that this problem becomes conspicuous as the curvature of the conveyance path increases with the miniaturization of the image reading apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus capable of improving the quality of a read image and a document conveying method in the image reading apparatus.

In order to achieve the above object, according to one aspect of the present invention, the image reading apparatus conveys a document in the conveyance path to a reading position provided facing the conveyance path, and causes the document to be read at the reading position. An image reading apparatus for acquiring image data, the first roller for feeding one original document from a paper feed tray positioned at the uppermost stream of the transport path to the transport path, and the first roller. A second roller that is arranged on the downstream side and adjusts the position of the document conveyed in the conveyance path, and is located downstream of the second roller and upstream and downstream of the conveyance path across the reading position. The third roller and the fourth roller for passing the document conveyed on the side of the conveyance path through the reading position, and the first roller for rotationally driving the first roller and the second roller. 1 driving means, a third roller and a fourth roller A second driving means for rotating driven, a clutch for turning on and off the transmission of rotation from the first drive means to the second roller, the image data read surface of the document reading position optically A reading means for obtaining and a control means connected to the first driving means and the second driving means for controlling the first driving means and the second driving means, the control means being conveyed that later the conveying direction of the leading end of the document has reached the third roller, the rear end in the conveying direction of the originals is first roller and the first to pass through the predetermined position between the second roller During the period, the second roller and the third roller are rotated by rotating the second roller at a predetermined rotation speed and rotating the third roller at a predetermined reading speed slower than the rotation speed of the second roller. of a first control for forming a loop between the rollers, first Later between, and at least the tip is a second period to reach the fourth roller, the second control gradually decreases the loop amount of the loop by causing gradually slow the rotational speed of the second roller Then, after the second period has elapsed, third control is executed to stop transmission of rotation to the second roller by turning off the clutch .

Preferably, the image reading apparatus is disposed between the first roller and the second roller in the vicinity of the first roller, and detects a timing at which the next original of the original is fed to the conveyance path. Therefore, a first sensor for detecting the presence or absence of the document at the sensing position on the transport path is further provided, and the predetermined position at which the rear end of the document transport direction passes at the end of the first period is the first position. This is the sensing position of the sensor.

Preferably, the image reading apparatus further includes a determination unit for determining a length of the document in the conveyance direction, and the control unit determines the length of the document in the conveyance direction from the second roller to the fourth roller. When it is determined that the length is equal to or greater than the length of the transport path, the first to third controls are executed in that order, and the length of the document in the transport direction is determined by the determination means from the second roller to the fourth roller The length of the longer one of the length of the transport path from the second roller to the third roller and the length of the transport path from the third roller to the fourth roller that is less than the length of the transport path If it is determined as described above, instead of the first control, the second roller is moved to the predetermined period after the first period until the trailing edge of the document passes the second roller. And the third roller is rotated at the rotational speed of the second roller. Instead of the fourth control that rotates at a slow reading speed, the second control, and the third control, the rotation is transmitted to the second roller by turning off the clutch after the third period has elapsed. The fifth control to be stopped is executed .

  More preferably, the image reading apparatus further includes a second sensor for detecting the presence or absence of a document at a sensing position of the paper feed tray in the paper feed tray, and the determination unit uses a sensor signal from the second sensor. Based on this, the length of the document in the conveyance direction is determined.

Good Mashiku includes an image reading apparatus is obtained from the sensor signal from the first sensor, the document is for determining the length of the conveying direction of the document based on the time which has passed through the sensing position of the first sensor The controller further includes a determination unit, and the control unit determines whether the length of the document in the conveyance direction is equal to or longer than the length of the conveyance path from the second roller to the fourth roller. In the order, the length of the document in the transport direction is less than the length of the transport path from the second roller to the fourth roller, and the second roller to the third roller. Instead of the first control when it is determined that the length is longer than the length of the transport path from the third roller to the fourth roller. From the end of the period until the trailing edge of the document passes the second roller A fourth control in which the second roller is rotated at a predetermined rotation speed during the third period, and the third roller is rotated at a reading speed slower than the rotation speed of the second roller; In place of the third control, the fifth control is executed to stop the transmission of the rotation to the second roller by turning off the clutch after the third period has elapsed .

  Preferably, before the first control, the control means moves the first roller at least for a period from the start of document conveyance to a predetermined time after the leading edge in the document conveyance direction reaches the second roller. Control is further executed to rotate at the paper feed speed defined in advance and stop the rotation of the second roller.

According to another aspect of the present invention, an original conveying method in an image reading apparatus includes an image reading apparatus that conveys an original in a conveying path to a reading position provided facing the conveying path, and reads the original at the reading position. The image reading apparatus includes a first roller for feeding one original document from a paper feed tray positioned at the uppermost stream of the transport path to the transport path. A second roller that is arranged downstream of the first roller and adjusts the position of the document conveyed in the conveyance path, and is downstream of the second roller and sandwiches the reading position. A third roller, a fourth roller, a first roller, and a second roller, which are arranged on the upstream side and the downstream side of the conveyance path and pass the document conveyed in the conveyance path through the reading position ; First driving means for rotationally driving the motor; 3 of the roller and a second drive means for rotating drives the fourth roller, and a clutch for turning on and off the transmission of rotation from the first drive means to the second roller, the reading position of the document and a reading means for obtaining image data by reading surface optically, from after the leading edge in the conveying direction of the document conveyed reaches the third roller, the rear end in the conveying direction of the originals first The second roller is rotated at a predetermined rotational speed and the third roller is rotated at a second rotational speed during a first period until the predetermined position between the second roller and the second roller passes the predetermined position. Forming a loop between the second roller and the third roller by rotating at a slower predetermined reading speed, and after the first period, at least the tip of the second roller becomes the fourth roller During the second period of time, the rotational speed of the second roller Comprising the steps of gradually decreasing the loop amount of the loop by slowing s, after the second period has elapsed, and a step of stopping the rotation of the second roller by turning off the clutch.

  According to the present invention, the quality of the read image can be improved and the reading efficiency can be improved.

1 is a diagram illustrating a specific example of a configuration of an image reading apparatus according to an embodiment. 2 is a control block diagram of the image reading apparatus according to the embodiment. FIG. It is a block diagram of an image processing part. FIG. 3 is a schematic diagram illustrating a roller configuration of an automatic document feeder. 6 is a flowchart illustrating a specific example of a transport operation for reading a document. It is a timing chart of control in conveyance operation. 10 is a flowchart illustrating another specific example of a transport operation for reading a document. 10 is a flowchart illustrating another specific example of a transport operation for reading a document.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

  Referring to FIG. 1, an image reading apparatus 1 according to an embodiment includes a sheet-through type automatic document feeder (hereinafter also referred to as ADF (Auto Document Feeder)) 101 and a reading apparatus 103. 1 is an MFP (Multi Function Peripheral) that is a copier, printer, scanner, facsimile transmitter / receiver, or a multi-function peripheral having a function of any two or more of these devices. ) And the like.

  In the ADF 101, the originals 100 stacked on the original tray 200 are sent out one by one to the conveyance path by the pickup roller 201 and the paper feed roller 220. In the following description, the transport direction of the transport path, that is, the original side in the direction from the document tray 200 to the stacking tray 214 is referred to as “upstream side in the transport direction”, and the front side in this direction is referred to as “downstream side in the transport direction”. Sometimes. Further, the upstream side of the transport path may be referred to as “front”, and the downstream side may be referred to as “rear”.

  The document sent to the conveyance path is transferred from the conveyance path (1) to (2) by the rotation of a plurality of roller pairs arranged across the conveyance path, such as the paper feed roller 220, the registration roller 219, and the pre-reading roller 213. ) To the reading position 211 by the reading device 103. The paper feed roller 220 is disposed in the vicinity of the pickup roller 201 downstream of the pickup roller 201, and rotates to send out one original 100 taken out from the original tray 200 by the pickup roller 201 to the conveyance path. The registration roller 219 is disposed downstream of the paper feed roller 220. The pre-reading roller 213 is disposed downstream of the registration roller 219 and immediately before a position on the conveyance path corresponding to the reading glass 215 of the reading device 103.

  The document that has passed the reading position 211 is conveyed in the direction of the conveyance path (3) by the rotation of the post-reading roller 212 and the paper discharge roller 223, each of which is a roller pair disposed across the conveyance path, and is discharged to the stacking tray 214. The The post-reading roller 212 is disposed downstream of the pre-reading roller 213 and immediately after a position on the conveyance path corresponding to the reading glass 215 of the reading device 103. The paper discharge roller 223 is disposed on the most downstream side of the conveyance path.

  When reading the back side of the original, the paper discharge roller 223 is temporarily stopped in a state where the rear end portion of the original 100 conveyed in the direction of the conveyance path (3) is pinched with respect to the conveyance direction. Rotate. As a result, the original 100 has the portion that was the trailing edge first as the leading edge, and passes through the branching path between the conveyance path (3) and the conveyance paths (3) and (4). It is conveyed in the direction toward the merging part. A conveyance path switching mechanism (not shown) is provided at a branch portion between the conveyance paths (3) and (4), and the original 100 conveyed by the reverse rotation of the paper discharge roller 223 from the conveyance path (3) is conveyed. It is conveyed from the path (4) to (2) and is conveyed again to the reading position 211 by the rotation of the registration roller 219 and the pre-reading roller 213.

  The pickup roller 201, the paper feed roller 220, and the registration roller 219 are rotationally driven by a first drive motor 231 that is a drive pulse motor denoted by M1 in FIG. 1, and a post-reading roller 212, a pre-reading roller 213, and The paper discharge roller 223 is rotationally driven by a second drive motor 232 that is a drive pulse motor represented by M2. The rotational speed and direction of rotation of these rollers are controlled by the control unit 501. A program executed by the control unit 501 is stored in the memory 601.

  The document tray 200 is provided with a guide member (not shown) for preventing the document 100 from being tilted during feeding and a sensor 221 for detecting the document size. The sensor 221 is provided at the rear end position with respect to the conveyance direction of the document 100 on the document tray 200, and detects the presence or absence of the document at the sensing position. A sensor signal from the sensor 221 is input to the control unit 501. As will be described later, the document size can be detected by a method other than the method based on the sensor signal from the sensor 221, and therefore the sensor 221 may not be provided.

  In addition, several sensors for detecting a document to be conveyed are provided on the conveyance path. As one of them, a sensor 222 for detecting the presence or absence of a document at the sensing position is arranged on the downstream conveyance path near the paper feed roller 220. Since the position where the sensor 222 is arranged is used to determine the timing for conveying the next document as will be described later, the sensor 222 is arranged at a position corresponding to a predetermined document conveyance interval. Further, a sensor 224 for detecting a document passing through the registration roller 219 is detected in the vicinity of the registration roller 219 by detecting the presence or absence of the document at the sensing position, and in the vicinity of the pre-reading roller 213 at the sensing position. A sensor 217 for detecting a document passing through the pre-reading roller 213 is detected by detecting the presence or absence of the document. Sensor signals from these sensors 222, 224, and 217 are all input to the control unit 501. Note that the detection of the document passing through the registration roller 219 can be performed by a method other than the method based on the sensor signal from the sensor 224 as described later, and thus the sensor 224 may not be provided.

  The reading device 103 can employ, for example, a CCD (Charged Coupled Device) system. In this case, when the document 100 passes through the reading position 211, the light source 206 irradiates the first surface shown below in FIG. The light reflected from the first surface of the document by the irradiated light is received by the CCD sensor 209 through the reading glass 215 which is an example of a plate-like transparent member, the mirror group 207 in the reading device 103, and the lens 208. The CCD sensor 209 converts the received light signal into RGB data by photoelectric conversion and outputs it to the control unit 503. A program executed by the control unit 503 is stored in the memory 603.

  The reading slider unit including the light source 206, the mirror group 207, the lens 208, and the CCD sensor 209 is movable, and is driven to move to the reading position 211 by a drive motor 235 represented by M in FIG. The movement of the reading slider unit is controlled by the control unit 503.

  Referring to FIG. 2, control unit 501 of ADF 101 and control unit 503 of reading apparatus 103 include CPUs (Central Processing Units) 515 and 513, respectively, and execute programs stored in memories 601 and 603. The CPU 515 of the ADF 101 and the CPU 513 of the reading device 103 are electrically connected to communicate with each other control information such as document size information, operation mode, and document reading timing information.

  A motor driving IC 511 for driving the first driving motor 231 and a motor driving IC 512 for driving the second driving motor 232 are connected to the CPU 515 of the ADF 101. The CPU 515 inputs the excitation signals φ0 to φ3 via the motor drive ICs 511 and 512 to rotate the drive motors 231 and 232. The CPU 515 changes the paper feed speed, the reading speed, and the like according to the reading magnification and the reading mode, and controls the synchronization of the document conveyance interval and the timing with the reading device 103.

  A sensor signal from the sensor 221 is input to the CPU 515 of the ADF 101, and the CPU 515 can determine the size of the document 100 based on the sensor signal. Alternatively, the guide member may be provided with a position detection sensor, or a plurality of document detection members may be provided in the document transport direction of the document tray 200, and the size of the document 100 is determined by a combination thereof. It may be possible. When the non-mixed mode indicating that the document size is only the same size is selected from an operation panel (not shown), the CPU 515 can calculate the read amount of the document based on the sensor signal from the sensor 221.

  Further, sensor signals from the sensors 222, 224, and 217 are input to the CPU 515 of the ADF 101, and the CPU 515 can detect the position of the document 100 being conveyed based on these sensor signals. In other words, the CPU 515 can detect that the document 100 has been sent out to the transport path based on the sensor signal from the sensor 222 and the transport has started. Further, based on the sensor signal from the sensor 224, it can be detected that it is the timing when the document 100 passes (or has passed) the registration roller 219. Further, based on the sensor signal from the sensor 217, it can be detected that it is the timing when the document 100 passes (or has passed) the pre-reading roller.

  A motor drive IC 505 for driving the drive motor 235 is connected to the CPU 513 of the reading device 103. The CPU 513 rotates the drive motor 235 by inputting the excitation signals φ0 to φ3 via the motor drive IC 505 based on the timing detected as described above.

  The control unit 503 of the reading device 103 includes an image input unit 518 for receiving input of RGB data from the CCD 209 and an image processing unit 519 for processing RGB data to generate image data. The image processing unit 519 is connected to the CPU 513.

  Referring to FIG. 3, image processing unit 519 accepts input of RGB data from image input unit 518 at input unit 11. The input RGB image data, which is analog image data, is converted into digital image data by an A / D (Analog / Digital) converter 12.

  The SH correction unit 13 reads a preset SH value, performs shading correction on the image data input from the A / D conversion unit 12, and outputs the image data after the shading correction to the brightness / color difference separation unit 14. The brightness / color difference separation unit 14 separates the image data into a brightness component and a color difference component, and outputs each to the image adjustment unit.

  The image adjustment unit includes a sharpness adjustment unit 15, an HVC adjustment unit 16, and a density correction unit 17. The sharpness adjustment unit 15 executes a process for sharpening the image, and the HVC adjustment unit 16 adjusts the hue (H), lightness (V), and saturation (C) of the image. The density correction unit 17 corrects the density of the image. The image adjustment unit outputs the processed RGB image data to the color space conversion unit 18. The color space conversion unit 18 converts the color space of the image data from the RGB color space to the L * a * b * color space, and outputs it to the compression / decompression unit 19. The compression / decompression unit 19 compresses the image data. The compression / decompression unit 19 stores the compressed image data in an image memory 30 such as an HDD (hard disk). Or output to an external device. For the sharpness adjustment unit 15, the HVC adjustment unit 16, and the density correction unit 17, the read image is optimized by the image parameter setting 32 for adjusting the image density and the like.

  Next, the roller configuration of the ADF 101 will be described with reference to FIG. FIG. 4A schematically shows the configuration of the pickup roller 201, the paper feed roller 220, and the registration roller 219 driven by the first drive motor 231. Referring to FIG. 4A, gears are attached to the rotation shafts of pickup roller 201, paper feed roller 220, registration roller 219, and first drive motor 231, respectively. The gears attached to the rotation shafts of the pickup roller 201, the paper feed roller 220, and the registration roller 219 directly or indirectly mesh with the gears attached to the rotation shaft of the first drive motor 231. Thereby, the rotation of the first drive motor 231 is transmitted to the pickup roller 201, the paper feed roller 220, and the registration roller 219.

  Clutchs are respectively attached to the rotation shafts of the sheet feeding roller 220 and the registration roller 219 between the sheet feeding roller 220 and the registration roller 219 and the gears. Transmission to 219 is turned on / off. In the following description, the clutch attached to the rotation shaft of the paper feed roller 220 is also referred to as “paper feed clutch”, and the clutch attached to the rotation shaft of the registration roller 219 is also referred to as “registration clutch”. Both clutches are connected to the CPU 515 and are turned on / off according to a control signal from the CPU 515. Further, a one-way clutch is attached between the registration roller 219 and the registration clutch. As a result, only rotation in one direction out of rotation by the gear is transmitted to the registration roller 219.

  FIG. 4B schematically shows the configuration of the post-reading roller 212, the pre-reading roller 213, and the paper discharge roller 223 driven by the second drive motor 232. Referring to FIG. 4B, gears are respectively attached to the rotation shafts of post-reading roller 212, pre-reading roller 213, paper discharge roller 223, and second drive motor 232. The gears attached to the rotation shafts of the post-reading roller 212, the pre-reading roller 213, and the paper discharge roller 223 directly or indirectly mesh with the gears attached to the rotation shaft of the second drive motor 232. Accordingly, the rotation of the second drive motor 232 is transmitted to the post-reading roller 212, the pre-reading roller 213, and the paper discharge roller 223.

  In the image reading apparatus 1, in order to correct the inclination (skew) of the document in the transport path, the transported document 100 is eliminated after forming a loop with the position of the registration roller 219 as the tip. In the following description, the loop with the registration roller 219 at the tip is also referred to as a “first loop”. Next, in order to reduce the load on the original at the reading position 211, the conveyed original 100 is eliminated after forming a loop with the position of the pre-reading roller 213 at the front end. In the following description, a loop having the position of the pre-reading roller 213 as a tip is also referred to as a “second loop”. Thus, the image reading apparatus 1 improves the quality of the read image.

  Incidentally, as shown in FIG. 1, the ADF 101 uses a conveyance path as a curve from the viewpoint of miniaturization, and conveys the document 100 along a conveyance path. In recent years, with the miniaturization of image reading apparatuses, the curvature tends to increase. In particular, as shown in FIG. 1, the curvature of the conveyance path from the registration roller 219 to the pre-reading roller 213 tends to increase. The inventors of the present application have found that as the image reading apparatus is further miniaturized and the curvature of the conveyance path is increased, the disturbance of the read image becomes noticeable in the process. And the inventors considered the possibility of the impact at the time of cancellation of the second loop as one of the reasons. This is because the curvature of the second loop formed there increases as the curvature of the transport path increases, and the impact upon cancellation increases, so the influence of the reading position on the document is considered to increase. Therefore, the image reading apparatus 1 performs control for suppressing an impact when the second loop is eliminated.

  A first specific example of the flow of document conveyance in the ADF 101 will be described using the flowchart of FIG. The operation shown in the flowchart of FIG. 5 is started at a timing when the user loads one or more originals 100 on the original tray 200 and instructs the start of a reading operation by an operation panel (not shown). In addition, the timing of control by the CPU 515 will be described with reference to the timing charts of FIGS. 6 (A) and 6 (B).

Referring to FIG. 5, when the reading operation is started first, CPU 515 detects the size of document 100 to be read in step S100. The document size may be detected based on an operation signal from the operation panel or based on a sensor signal from a sensor 221 provided on the document tray 200. Document size detected here, whose length in the conveying direction of the document is the length L1 or more from the registration roller 219 until the rear roller 212 reading is "large", less than the length L1, or One read preparative Those having a length L2 or more from the front roller 213 to the post-read roller 212 are classified as “small”. That is, when the leading edge of the document reaches the post-reading roller 212, the size of the document whose length is upstream from the registration roller 219 is “large”, and when the leading edge reaches the post-reading roller 212, the trailing edge is already reached. The size of the document whose end passes through the registration roller 219 and is upstream of the pre-reading roller 213 is determined to be “small”.

  If it is determined in step S100 that the document size is “large” (“large” in step S100), in step S101, the CPU 515 turns off the sheet feeding clutch and the registration clutch and rotates the sheet feeding roller 220 and the registration roller 219. Block transmission. Thereafter, in step S103, the CPU 515 accelerates the first drive motor 231 and the second drive motor 232 to a rotation speed Vf corresponding to a predetermined paper feed speed and a rotation speed Vr corresponding to a reading speed, respectively. . In the flowchart of FIG. 5 and the timing chart of FIG. 6, the first drive motor 231 is represented as “paper feed motor”, and the second drive motor 232 is represented as “reading motor”. Here, a relationship of Vf> Vr is established between the rotation speed Vf of the first drive motor 231 corresponding to the paper feed speed and the rotation speed Vr of the second drive motor 232 corresponding to the reading speed.

  When acceleration is completed until the rotational speed of the first drive motor 231 reaches a predetermined speed (YES in step S105), the CPU 515 turns on the paper feed clutch in step S107 and starts the rotation of the paper feed roller 220. . As a result, conveyance of one document 100 out of the documents loaded on the document tray 200 is started, and the document 100 is conveyed on the conveyance path at a predetermined feeding speed. Since the registration clutch is turned off at this point, the conveyed document 100 is conveyed only to the position of the registration roller 219 and the leading edge does not pass the registration roller 219. However, since the rotation of the paper feed roller 220 is continued, the conveyance of the document 100 is continued. Therefore, the formation of the first loop starting from the position of the registration roller 219 is started from step S107.

  In step S109, the CPU 515 detects completion of the correction of the skew by detecting whether or not the first loop has been formed to a predetermined loop amount that is defined in advance as a loop amount for which the correction of the skew is completed. In step S109, for example, it may be detected that the elapsed time from the start of conveyance in step S107 has reached a predetermined time stored in advance corresponding to the loop amount, or in order to detect a loop amount (not shown). It may be detected that the predetermined loop amount has been reached by the sensor.

When it is detected that the first loop reaches the predetermined loop amount and the skew correction is completed (YES in step S109), the CPU 515 turns off the paper feed clutch and rotates the paper feed roller 220 in step S111. Is stopped and the registration clutch is turned on . This ensures that the registration roller 219 starts to rotate at a predefined paper feed speed.

  The operation of rotating the sheet feed roller 220 until the loop amount of the first loop reaches a predetermined amount after turning off the registration clutch and stopping the rotation of the registration roller 219 in step S101 (or step S119 described later). 6 is an example of an operation for correcting skew of the conveyed document 100. Therefore, instead of these operations, other operations for correcting the skew may be performed. Alternatively, these operations may not be performed. That is, when the leading edge of the document 100 reaches the registration roller 219, the CPU 515 may turn on the registration clutch without starting the first loop and start the rotation of the registration roller 219.

  When the document size is “large”, referring to the timing chart of FIG. 6A, the timing of step S111 corresponds to time T0. Under the control of step S111, the delivery of a new document from the document tray 200 to the carry-in path is stopped, and the cancellation of the first loop is started from time T0. Since the original 100 is passing the position of the sensor 222, in this state, the CPU 515 detects that the sensor signal from the sensor 222 is ON.

  When the leading edge of the document 100 passes through the registration rollers 219 and reaches the pre-reading roller 213 by the control in step S111, the vicinity of the leading edge of the document 100 is sandwiched between the pre-reading rollers 213 and the upstream side is sandwiched between the registration rollers 219. The leading end is sent out downstream of the pre-reading roller 213. The pre-reading roller 213 rotates at a predetermined reading speed. Even when the front end of the original 100 does not reach the post-reading roller 212 on the downstream side of the pre-reading roller 213, the vicinity of the front end of the original 100 is nipped by the pre-reading roller 213 and conveyed downstream. By doing so, it passes through the reading position 211 at a predetermined reading speed. As a result, the document 100 is read by the reading device 103.

  Here, since the paper feeding speed is faster than the reading speed, the conveyance speed of the portion nipped by the registration roller 219 is faster than the conveyance speed of the portion nipped by the pre-reading roller 213 of the document 100. Become. As a result, the original 100 starts to form a second loop with the position of the pre-reading roller 213 as the front end when the front end of the original 100 reaches the pre-reading roller 213.

  In step S113, the CPU 515 monitors the input of the sensor signal from the sensor 222, and confirms that the rear end of the document 100 has passed the position of the sensor 222 at time T1 in FIG. 6A when the sensor signal is turned off. To detect. The timing at which the trailing edge of the document 100 passes the position of the sensor 222 is set in advance as a timing at which the CPU 515 starts preparation for transporting the next document. Therefore, when CPU 515 detects that the trailing edge of document 100 has passed the position of sensor 222 at time T1, the preparation for transporting the next document or the transport of document 100 that is currently being read ends. Start processing for.

  In order to start the conveyance of the next original or to end the conveyance of the original 100, it is necessary to stop the rotation of the registration roller 219 rotating at the paper feed speed. However, if the rotation of the registration roller 219 is stopped in a state where the second loop is formed, the second loop is eliminated at once. Therefore, when CPU 515 detects that the trailing edge of document 100 has passed the position of sensor 222 (YES in step S113), CPU 515 starts decelerating the rotational speed of first drive motor 231 in step S115. As a result, the loop amount of the second loop formed by the document 100 is gradually reduced. That is, the cancellation of the second loop is started from time T1 in FIG. 6A, which is the timing of step S115. As shown in FIG. 6A, the rotation speed of the first drive motor 231 gradually decreases from time T1 by the control in step S115.

  As shown in FIG. 4A, since a one-way clutch is attached between the registration roller 219 and the registration clutch, the rotation speed of the registration roller 219 is higher than the rotation speed of the pre-reading roller 213. Accordingly, the load on the document 100 held by these rollers can be reduced.

  When the CPU 515 detects the elapse of a predetermined time from the time T1 at which the rotation speed of the first drive motor 231 starts to decrease to the time T2, the CPU 515 determines that the rotation speed reduction of the first drive motor 231 has been completed (step S117). YES), the deceleration of the rotational speed of the first drive motor 231 is completed. Time T2 is a time after the time when the leading edge of the document 100 reaches the post-reading roller 212, and the predetermined time is defined in advance based on the document size, the paper feeding speed, the reading speed, the arrangement position of each roller, and the like. ing.

  Alternatively, when a sensor (not shown) is arranged in the vicinity of the post-reading roller 212 and the presence / absence of the document at the sensing position can be detected, the CPU 515 uses the sensor signal from the sensor instead of detecting the passage of the predetermined time. Based on this, it may be detected that the leading edge of the document 100 has reached the post-reading roller 212, and based on this, the reduction of the rotational speed of the first drive motor 231 may be terminated.

When deceleration of the rotational speed of the first drive motor 231 is completed at time T2 (YES in step S117), the CPU 515 turns off the registration clutch in step S119. As a result, the transmission of rotation to the registration roller 219 is stopped.

  When there is a next document to be read (YES in step S121), in step S123, the CPU 515 determines the rotation speed Vf corresponding to the sheet feeding speed as the rotation speed of the first drive motor 231 decelerated in step S115. To speed up. When the rotation speed of the first drive motor 231 reaches the rotation speed Vf (YES in step S125), the process returns to step S107, and the subsequent processes are repeated. That is, after confirming that the rotation speed of the first drive motor 231 has reached the rotation speed Vf, the CPU 515 turns on the paper feed clutch in step S107. In the timing chart of FIG. 6A, the rotational speed of the first drive motor 231 is accelerated from time T3 when it is confirmed that there is a next original, and the paper feed clutch is turned on at time T4 when the rotational speed Vf is reached. Has been. As a result, at time T4, the paper feed roller 220 starts rotating at the paper feed speed, and conveyance of the next original 100 is started.

  On the other hand, when there is no next original to be read (NO in step S121), when the discharge of the original 100 to the stacking tray 214 is completed (YES in step S127), the CPU 515 performs the first operation in step S129. The driving motor 231 and the second driving motor 232 are stopped, and the conveyance operation for reading a series of documents is completed.

  Normally, when it is detected that the trailing edge of the original 100 has passed the position of the sensor 222 in order to start conveying the next original or to end the conveyance of the original 100, the registration clutch is turned off at that time. Thus, it is conceivable to control the paper feeding clutch to be turned on after the rotation of the registration roller 219 is stopped and to start the conveyance of the next document. However, in such a case, as described above, when it is detected that the trailing edge of the document 100 has passed the position of the sensor 222, the document 100 has a second loop with the position of the pre-reading roller 213 as the leading edge. The second loop is eliminated all at once. If the leading edge of the document 100 is before reaching the post-reading roller 212 when the second loop is canceled, vibrations associated with the cancellation of the second loop occur in the document 100, and the document at the reading position 211. 100 will vibrate.

  Alternatively, the rotational speed Vf of the registration roller 219 is maintained until the leading edge of the document 100 reaches the post-reading roller 212, and the registration clutch is turned off when the leading edge of the document 100 reaches the post-reading roller 212. It is conceivable to control the paper feeding clutch to be turned on after the rotation of the paper is stopped and to start the conveyance of the next document. As a result, the second loop is eliminated while the document 100 is nipped by the pre-reading roller 213 and the post-reading roller 212 with the reading position 211 in between, so that the second loop is eliminated. This is because the influence of the vibration on the document 100 at the reading position 211 can be suppressed. However, in such a case, the conveyance of the next document cannot be started until the leading edge of the document 100 reaches the post-reading roller 212, leading to a decrease in reading efficiency.

  On the other hand, in the above-described operation, the rotation speed of the first drive motor 231 is started to be reduced in step S115 and gradually reduced between time T1 and time T2, so that the time between time T1 and T2 is reached. That is, at least in the period before the leading edge of the document 100 passes through the pre-reading roller 213 and reaches the post-reading roller 212, the second loop is gradually eliminated. Thereby, it is possible to suppress the occurrence of vibration associated with the elimination of the second loop in the period before the leading edge of the document 100 passes through the pre-reading roller 213 and reaches the post-reading roller 212. That is, it is possible to achieve both improvement in reading efficiency and improvement in quality of a read image.

  If the document size is determined to be “small” (“small” in step S100), steps S101 ′ to S111 ′, which are the same operations as steps S101 to S111 when the document size is determined to be “large”, are performed. Executed. However, in this case, the first drive motor 231 is not decelerated in step S115 when it is determined that the document size is “large”. Instead of this operation, when it is detected that the trailing edge of the document has passed the registration roller 219 (YES in step S113 '), the CPU 515 turns off the registration clutch in step S119'.

  The detection in step S113 'is performed based on a detection signal from the sensor 224 when the ADF 101 includes the sensor 224 as shown in FIG. If the sensor 224 is not provided, the transport time obtained based on the transport distance to the registration roller 219 and the paper feed speed is stored in advance, and is based on the elapsed time from the start of transport of the document 100. Also good.

  When the document size is “small”, refer to the timing chart of FIG. 6B. When the document size is “small”, the length of the document in the transport direction is larger than that when the document size is “large”. Therefore, the time T1 ′ when the trailing edge of the document 100 passes the position of the sensor 222 is earlier than the time T1 when the document size is “large”. However, when the document size is “small”, the CPU 515 maintains the rotational speed Vf of the first drive motor 231 without starting the deceleration of the first drive motor 231 from time T1 ′. Then, the registration clutch is turned off at time T <b> 2 ′ when the trailing edge of the document 100 passes the registration roller 219. That is, the registration clutch is turned off and the rotation of the registration roller 219 is stopped without gradually eliminating the second loop in advance.

  This is because, when it is detected that the trailing edge of the document 100 passes the registration roller 219, the leading edge passes the post-reading roller 212, and at that time, the document 100 sandwiches the reading position 211 and the pre-reading roller 213. And the post-reading roller 212, and even if the rotation of the registration roller 219 is stopped at that time, the impact of the cancellation of the second loop on the original at the reading position 211 is small. It is. Further, since the length of the document 100 in the transport direction is sufficiently shorter than that of the document size “large”, the registration clutch is turned off after detecting that the trailing edge of the document 100 passes the registration roller 219. This is because even if the conveyance of the next document is started, the reading efficiency is not lowered as compared with the case where the conveyance of the next document is started at the same timing when the document size is “large”.

Thereafter, when the document size is “small” and there is a next document to be read (YES in step S121 ′), the process returns to step S107 ′ and the subsequent processes are repeated. On the other hand, (NO in step S121 '). If no next original to be read of the object is, the same operation as steps S 127 ~S129 when the document size "large" is performed, for a series of document read This completes the transport operation.

  Thus, when the document size is “small”, an operation different from the operation when the document size is “large” is performed. That is, the rotational speed of the first drive motor 231 is gradually reduced and the second loop is gradually moved. By not performing the canceling operation, the timing for starting the conveyance of the next document can be advanced when the document size is “small”. For this reason, it is possible to achieve both improvement in reading efficiency and improvement in quality of a read image.

[Modification 1]
In the specific example of the operation shown in the flowchart of FIG. 5, the document size is determined based on the sensor signal from the sensor 221 on the document tray 200 or the operation signal from the operation panel (not shown) in step S100. However, the determination of the document size is not limited to this method, and other methods may be used. As another method, in Modification 1, an example in which determination is performed based on a sensor signal from the sensor 222 will be described using the flowchart of FIG.

  Referring to FIG. 7, in the operation according to the first modification, the above-described operations in steps S101 to S111 are performed without determining the document size in step S100. When the rotation of the paper feed roller 220 is stopped and the rotation of the registration roller 219 is started in step S111, the CPU 515 monitors the sensor signal from the sensor 222 and passes the position of the sensor 222 from the front end to the rear end of the document 100. Time is measured. That is, when the trailing edge of the document 100 passes the position of the sensor 222 (YES in step S113), the passage time of the position of the sensor 222 of the document 100 is equal to or longer than a predetermined time, that is, in the transport direction. If the length of the document 100 is equal to or longer than the predetermined length, the CPU 515 determines that the document size is “large” (“large” in step S114), and thereafter performs the operations from step S115 described above. If not, the CPU 515 determines that the document size is “small” (YES in step S113 and “small” in S114), and thereafter performs the operations after step S119 ′ described above.

  Although an example in which the document size is determined based on a sensor signal from the sensor 222 as an example in which the document size is determined without using the sensor 221 on the document tray 200 or the operation on the operation panel is shown. A similar determination can be made using sensor signals from other sensors.

  By determining the document size in this way, even if a plurality of document groups are mixed in document size or have different document orientations, the document size can be accurately determined. Judgment can be made.

[Modification 2]
In the above description, the operation for gradually eliminating the second loop according to the size of the document to be conveyed (the operation on the left side of the flowchart of FIG. 5) and the operation for not performing such an operation (the right side of the flowchart of FIG. 5). Branching to the operation). By doing so, the quality of the read image can be ensured when the document size is large, and the efficiency of the read operation can be ensured when the document size that does not require such operation is small. it can.

  However, when reading a document, the efficiency (speed) of the reading operation may be more important than the quality of the read image. In order to meet such a user's request, the image reading apparatus 1 has a “image quality priority mode” in which the quality of the read image is more important than the efficiency (speed) of the reading operation as the reading mode, and the quality of the read image. It is assumed that a “speed priority mode” that places importance on the efficiency (speed) of the reading operation is provided. In this case, as shown in the flowchart of FIG. 8, the CPU 515 first checks which mode the reading mode is in step S99, and if it is “image quality priority mode” (YES in step S99). The same operation as that shown in the flowchart of FIG. 5 is performed. On the other hand, when the “speed priority mode” is set (NO in step S99), the determination of the document size in step S100 is not performed, that is, the operation when the document size is “small” regardless of the size of the document. That is, the operation on the right side of the flowchart of FIG. 5 is performed. In the flowchart of FIG. 8, only the operations up to steps S103 and S103 'are shown for the sake of simplicity of explanation, but thereafter the operations up to step S129 shown in the flowchart of FIG. 5 are performed.

  As described above, by branching the operation depending on which one of the quality of the read image and the efficiency (speed) of the read operation is prioritized, it is possible to improve both the read efficiency and the quality of the read image. .

  A program for executing the above-described operation can also be provided. Such a program is stored in a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), and a memory card. And can be provided as a program product. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.

  Such a program may be a program module that is provided as a part of an operating system (OS) of a computer and that calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program for executing the above-described operation.

  Such a program may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program for executing the above-described operation.

  The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image reader, 11 Input part, 12 A / D conversion part, 13 SH correction part, 14 Lightness and color difference separation part, 15 Sharpness adjustment part, 16 HVC adjustment part, 17 Color space conversion part, 18 Density correction part, 19 Compression / decompression unit, 30 image memory, 32 image parameter setting, 100 original, 101 ADF, 103 reading device, 200 original tray, 201 pickup roller, 206 light source, 207 mirror group, 208 lens, 209 CCD sensor, 211 reading position, 212 Post-reading roller, 213 Pre-reading roller, 214 Stack tray, 215 Reading glass, 217 sensor, 219 Registration roller, 220 Paper feed roller, 221 Sensor, 222 sensor, 223 Paper discharge roller, 224 sensor, 231 First drive motor, 232 second drive motor, 2 35 drive motor, 501 control unit, 503 control unit, 505 motor drive IC, 511 motor drive IC, 512 motor drive IC, 515 CPU, 513 CPU, 518 image input unit, 519 image processing unit, 601 memory, 603 memory.

Claims (7)

An image reading apparatus that conveys a document in the conveyance path to a reading position provided facing a conveyance path, and acquires image data by reading the document at the reading position.
A first roller for feeding one document from the paper feed tray located at the uppermost stream of the transport path to the transport path;
A second roller that is arranged downstream of the first roller and adjusts the position of the document conveyed in the conveyance path;
In order to pass the document, which is arranged downstream of the second roller and upstream and downstream of the conveyance path with the reading position in between, and conveyed in the conveyance path, through the reading position. A third roller and a fourth roller of
First driving means for rotationally driving the first roller and the second roller;
A second driving means for rotationally driving the third roller and the fourth roller;
A clutch for turning on and off transmission of rotation from the first driving means to the second roller;
Reading means for optically reading the surface of the document at the reading position to obtain the image data;
Control means connected to the first driving means and the second driving means for controlling the first driving means and the second driving means;
The control means includes
Predetermined position between the after the leading edge in the transport direction of the document conveyed reaches the third roller, and the second roller rear end in the carrying direction and the first roller before SL document The second roller is rotated at a predetermined rotational speed for a first period until the second pass, and the third roller is rotated at a predetermined reading speed that is slower than the rotational speed of the second roller. A first control that forms a loop between the second roller and the third roller by rotating;
After the first period, at least in the second period until the tip reaches the fourth roller, the rotation amount of the loop is gradually decreased by gradually decreasing the rotation speed of the second roller. A second control to decrease ;
An image reading apparatus that performs third control to stop transmission of rotation to the second roller by turning off the clutch after the second period has elapsed. In the vicinity of the first roller and between the first roller and the second roller, the transport is performed to detect the timing of feeding the document next to the document to the transport path. A first sensor for detecting the presence or absence of the document at a sensing position on the path;
Wherein the predetermined position where the rear end in the conveying direction passes the document to the end of the first period is sensing the position of the first sensor, the image reading apparatus according to claim 1. A determination unit for determining a length of the document in the transport direction;
The control means includes
When the determination unit determines that the length of the document in the transport direction is equal to or longer than the length of the transport path from the second roller to the fourth roller, the first to third controls are performed. Run in that order ,
In the determination unit, the length of the document in the transport direction is less than the length of the transport path from the second roller to the fourth roller, and from the second roller to the third roller. Instead of the first control when it is determined that the length is longer than the length of the transport path from the third roller to the fourth roller. The second roller is rotated at the predetermined rotational speed for a third period from the end of the first period until the trailing edge of the document passes the second roller, and the second period In place of the fourth control for rotating the third roller at the reading speed slower than the rotational speed of the second roller, the second control, and the third control, the third period has elapsed. The second low is achieved by later turning off the clutch. Executing a fifth control of stopping the transmission of rotation to the image reading apparatus according to claim 1 or 2. The paper feed tray further comprises a second sensor for detecting the presence or absence of the document at the sensing position of the paper feed tray,
The image reading apparatus according to claim 3, wherein the determination unit determines a length of the document in the transport direction based on a sensor signal from the second sensor. And a determination unit configured to determine a length of the document in the conveyance direction based on a time when the document passes through a sensing position of the first sensor, which is obtained from a sensor signal from the first sensor. ,
The control means includes
When the determination unit determines that the length of the document in the transport direction is equal to or longer than the length of the transport path from the second roller to the fourth roller, the first to third controls are performed. Run in that order ,
In the determination unit, the length of the document in the transport direction is less than the length of the transport path from the second roller to the fourth roller, and from the second roller to the third roller. Instead of the first control when it is determined that the length is longer than the length of the transport path from the third roller to the fourth roller. The second roller is rotated at the predetermined rotational speed for a third period from the end of the first period until the trailing edge of the document passes the second roller, and the second period In place of the fourth control for rotating the third roller at the reading speed slower than the rotational speed of the second roller, the second control, and the third control, the third period has elapsed. The second low is achieved by later turning off the clutch. Executing a fifth control of stopping the transmission of rotation to the image reading apparatus according to claim 2. Prior to the first control, the control means includes at least a period from the start of conveyance of the document to a predetermined time after the leading edge of the document in the conveyance direction reaches the second roller. rotating the first roller in a predefined paper feed rate, and said second control to stop the rotation of the rollers further executes image reading apparatus according to any one of claims 1-5. In the image reading apparatus, transporting the document for transporting the document in the transport path to a reading position provided facing the transport path, and acquiring the image data by reading the document at the reading position. A method,
The image reading device includes:
A first roller for feeding one document from the paper feed tray located at the uppermost stream of the transport path to the transport path;
A second roller that is arranged downstream of the first roller and adjusts the position of the document conveyed in the conveyance path;
In order to pass the document, which is arranged downstream of the second roller and upstream and downstream of the conveyance path with the reading position in between, and conveyed in the conveyance path, through the reading position. A third roller and a fourth roller of
First driving means for rotationally driving the first roller and the second roller;
A second driving means for rotationally driving the third roller and the fourth roller;
A clutch for turning on and off transmission of rotation from the first driving means to the second roller;
Reading means for optically reading the surface of the original at the reading position to obtain the image data;
Predetermined position between the after the leading edge in the transport direction of the document conveyed reaches the third roller, and the second roller rear end in the carrying direction and the first roller before SL document The second roller is rotated at a predetermined rotational speed for a first period until the second pass, and the third roller is rotated at a predetermined reading speed that is slower than the rotational speed of the second roller. Forming a loop between the second roller and the third roller by rotating;
After the first period, at least in the second period until the tip reaches the fourth roller, the rotation amount of the loop is gradually decreased by gradually decreasing the rotation speed of the second roller. Reducing steps,
And a step of stopping the transmission of rotation to the second roller by turning off the clutch after the second period has elapsed.

Images