JP6138064B2 - Sheet conveying apparatus, image reading apparatus, image forming apparatus, and sheet conveying method - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, an image reading apparatus, an image forming apparatus, and a sheet conveying method for conveying a sheet from a sheet placing section to a sheet discharging section.

  An image reading apparatus such as a scanner capable of reading an image of an original document may be provided with a sheet conveying apparatus that conveys a sheet from a sheet placement unit to an sheet discharging unit through an image reading position. In this type of image reading apparatus, it is possible to automatically read an image from a plurality of documents by setting a plurality of documents on the sheet placement unit. At this time, in the sheet conveying apparatus, a conveying sound is generated when the sheet is conveyed by a conveying roller or the like. For example, when a sheet having a high rigidity such as thick paper is conveyed by the sheet conveying apparatus, a large conveying sound is generated. On the other hand, a technique is known in which the stiffness of a conveyed sheet is detected and the sheet conveyance speed is controlled according to the detection result (see, for example, Patent Document 1).

JP 2010-52933 A

  However, even when a sheet having low rigidity is conveyed by the sheet conveying apparatus, for example, when the image reading apparatus is used in a quiet environment, the conveying sound of the sheet may be heard as a large noise. On the other hand, conveying sound is suppressed by slowing the sheet conveying speed in the sheet conveying apparatus. However, if the sheet conveyance speed is slowed down, the time required to read an image from a large amount of originals becomes long. That is, there is a trade-off relationship between the suppression of the conveyance sound and the speeding up of the image reading.

  An object of the present invention is to provide a sheet conveying apparatus, an image reading apparatus, an image forming apparatus, and a sheet conveying method capable of achieving a good balance between suppression of sheet conveying sound and high speed image reading.

  A sheet conveying apparatus according to an aspect of the present invention includes conveying means and conveying speed control means. The conveying unit can continuously convey a plurality of sheets from the sheet placing unit to the sheet discharging unit. The conveyance speed control means gradually increases the conveyance speed of the sheets continuously conveyed by the conveyance means from a predetermined first speed to a second speed.

  An image reading apparatus according to another aspect of the present invention includes a sheet conveying device and an image reading unit. The sheet conveying apparatus includes conveying means and conveying speed control means. The conveying unit can continuously convey a plurality of sheets from the sheet placing unit to the sheet discharging unit. The conveyance speed control means gradually increases the conveyance speed of the sheets continuously conveyed by the conveyance means from a predetermined first speed to a second speed. The image reading unit can read image data from a sheet conveyed by the sheet conveying apparatus.

  An image forming apparatus according to another aspect of the present invention includes an image reading device and an image forming unit. The image reading device includes a sheet conveying device and an image reading unit, and the sheet conveying device includes a conveying unit and a conveying speed control unit. The conveying unit can continuously convey a plurality of sheets from the sheet placing unit to the sheet discharging unit. The conveyance speed control means gradually increases the conveyance speed of the sheets continuously conveyed by the conveyance means from a predetermined first speed to a second speed. The image reading unit can read image data from a sheet conveyed by the sheet conveying apparatus. The image forming unit can form an image based on read image data read by the image reading device.

  A sheet conveying method according to another aspect of the present invention is a sheet conveying method executed by a sheet conveying apparatus, and includes the following first step and second step. In the first step, the conveyance of the sheet from the sheet placement unit to the sheet discharge unit is started at a predetermined first speed. In the second step, the conveyance speed of the sheet is gradually increased from the first speed toward a predetermined second speed.

  According to the present invention, it is possible to achieve a good balance between suppression of sheet conveyance noise and high speed image reading.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing a system configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of an ADF of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of an ADF of an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating an example of a conveyance speed control process executed by the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an example of a conveyance speed control process executed by the image forming apparatus according to the embodiment of the present invention.

  In the following, an embodiment of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Schematic Configuration of Image Forming Apparatus 10]
First, a schematic configuration of an image forming apparatus 10 according to an embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a schematic sectional view of the image forming apparatus 10. 3 is a schematic cross-sectional view showing the conveyance port 111 of the document placing portion 11. FIG. 3A shows a state when the lift member 113 is lowered, and FIG. 3B shows a state where the lift member 113 is raised. It is a figure which shows the state of time. Note that the thick line in FIG. 3 indicates the document. FIG. 4 is a plan view showing the configuration of the document placing portion 11.

  As shown in FIGS. 1 and 2, the image forming apparatus 10 includes an ADF 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, and an operation display unit 6. The image forming apparatus 10 is a multifunction device having a plurality of functions such as a printer function, a facsimile function, and a copy function, in addition to a scan function for reading image data from a document. Note that the image forming apparatus 10 includes the ADF 1 and the control unit 5 as an example of a sheet conveying apparatus according to the present invention. The present invention can also be applied to image reading apparatuses or image forming apparatuses such as scanner apparatuses, facsimile apparatuses, and copiers.

  The image forming unit 3 performs an image forming process (printing process) based on image data read by the image reading unit 2 or image data input from an information processing apparatus such as an external personal computer. The image forming unit. Specifically, as shown in FIG. 1, the image forming unit 3 includes a photosensitive drum 31, a charging device 32, an exposure device (LSU) 33, a developing device 34, a transfer roller 35, a cleaning device 36, a fixing roller 37, A pressure roller 38 and a paper discharge tray 39 are provided. In the image forming unit 3, an image is formed on the paper supplied from the paper feed cassette 41 that can be attached to and detached from the paper feed unit 4 according to the following procedure, and the paper after the image formation is discharged to the paper discharge tray 39. Is done.

  First, the photosensitive drum 31 is uniformly charged to a predetermined potential by the charging device 32. Next, the exposure device 33 irradiates the surface of the photosensitive drum 31 with light based on image data. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 31. The electrostatic latent image on the photosensitive drum 31 is developed (visualized) as a toner image by the developing device 34. The developing device 34 is supplied with toner (developer) from a toner container 34 </ b> A that can be attached to and detached from the image forming unit 3. Subsequently, the toner image formed on the photosensitive drum 31 is transferred onto a sheet by the transfer roller 35. Thereafter, the toner image transferred to the sheet is heated and fixed by the fixing roller 37 when the sheet passes between the fixing roller 37 and the pressure roller 38. The toner remaining on the surface of the photosensitive drum 31 is removed by the cleaning device 36.

  The control unit 5 includes control devices such as a CPU, ROM, RAM, and EEPROM (not shown). The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile storage unit in which information such as a control program for causing the CPU to execute various processes is stored in advance. The RAM is a volatile storage unit, and the EEPROM is a non-volatile storage unit. The RAM and the EEPROM are used as a temporary storage memory (working area) for various processes executed by the CPU. Then, the control unit 5 comprehensively controls the image forming apparatus 10 by executing various control programs stored in advance in the ROM using the CPU. The control unit 5 may be an electronic circuit such as an integrated circuit (ASIC), and is provided separately from a main control unit that controls the image forming apparatus 10 in an integrated manner. It may be.

  The operation display unit 6 includes a display unit such as a liquid crystal display that displays various types of information according to control instructions from the control unit 5, and a hardware that inputs various types of information to the control unit 5 according to user operations. An operation unit such as a key or a touch panel is provided. Here, the operation display unit 6 is an example of an operation unit.

  As shown in FIG. 1, the image reading unit 2 includes a document table 21, a reading unit 22, mirrors 23 and 24, an optical lens 25, and a CCD (Charge Coupled Device) 26. The document table 21 is a document placement unit provided on the upper surface of the image reading unit 2. The reading unit 22 includes an LED light source 221 and a mirror 222, and is movable in a sub-scanning direction (left and right direction in FIG. 1) by a motor (not shown). The LED light source 221 includes a large number of white LEDs arranged along the main scanning direction (the depth direction in FIG. 1). The mirror 222 reflects the light emitted from the LED light source 221 and reflected by the surface of the document at the reading position on the document table 21 toward the mirror 23. The light reflected by the mirror 222 is guided to the optical lens 25 by the mirrors 23 and 24. The optical lens 25 collects incident light and makes it incident on the CCD 26. The CCD 26 includes a photoelectric conversion element that inputs an electrical signal corresponding to the amount of light incident from the optical lens 25 to the control unit 5 as image data of the document.

  The ADF 1 is an automatic document feeder that conveys a document read by the image reading unit 2. Specifically, as shown in FIGS. 1 and 3 to 4, the ADF 1 includes a document placement unit 11, a plurality of transport rollers 12, a document press 13, a paper discharge unit 14, a passage detection sensor 15, and a distance detection sensor. 16, an inclination regulating member 17, and original detection sensors 18A and 18B.

  The document placing unit 11 is a document placing table on which a document to be read by the image reading unit 2 is placed. The document placed on the document placement unit 11 is transported from the transport port 111 formed in the casing of the ADF 1 toward the paper discharge unit 14. Specifically, as shown in FIG. 3A, the document placing portion 11 is inclined downward toward the conveyance direction 112, and a document can be stacked below the conveyance port 111. A space is formed. Further, a lift member 113 for lifting the placed document to the transport port 111 is provided on the side of the document placement unit 11 in the transport direction 112. For example, as shown in FIGS. 3A and 3B, the lift member 113 is pivotally supported at one end opposite to the transport direction 112, and the other end is rotated by a driving means (not shown) such as a motor. By doing so, the document can be lifted. Then, the document lifted by the lift member 113 is transported into the housing of the ADF 1 by a pickup roller 114 provided at the transport port 111. Here, the document placing portion 11 is an example of a sheet placing portion.

  In the ADF 1, the pickup roller 114 is disposed so as to be able to be pushed up, and a sensor 115 capable of detecting the push-up of the pickup roller 114 is provided above the pickup roller 114. The driving unit rotates the lift member 113 until the sensor 115 detects that the pickup roller 114 is pushed up by the document placed on the lift member 113. For example, the sensor 115 is a transmissive optical sensor having a light emitting part and a light receiving part, and detects the interruption of the optical path by the blocking member 116 arranged to be interlocked with the push-up of the pickup roller 114.

  The transport roller 12 is provided on the transport path of the document inside the ADF 1 and is driven by a motor (not shown) so that the document sent from the transport port 111 is read by the image reading unit 2. The sheet passes through the position and is conveyed to the paper discharge unit 14. The document presser 13 presses the document passing through the reading position onto the document table 21. As a result, the image reading unit 2 can read image data from a document conveyed by the ADF 1. Here, the paper discharge unit 14 is an example of a sheet discharge unit.

  As shown in FIG. 1, the passage detection sensor 15 is disposed on the document transport path inside the ADF 1, and detects passage of the document at the placement position. For example, the passage detection sensor 15 is a transmissive optical sensor having a light emitting part and a light receiving part. The passage detection sensor 15 outputs an electric signal indicating whether or not a document has passed to the control unit 5.

  As shown in FIG. 3, the distance detection sensor 16 is provided on the lower side of the lift member 113, and the distance from the arrangement position of the distance detection sensor 16 in the vertical direction to the bottom surface on the other end side of the lift member 113. (Height) is detected. For example, the distance detection sensor 16 is a reflective optical sensor having a light emitting part and a light receiving part. The distance detection sensor 16 outputs an electrical signal corresponding to the distance from the position where the distance detection sensor 16 is disposed to the bottom surface on the other end side of the lift member 113 to the control unit 5.

  As shown in FIG. 4, the tilt restricting member 17 is a pair of plate-like members disposed on the lift member 113 so as to face each other in a direction perpendicular to the transport direction 112. The tilt regulating member 17 is provided so as to be able to be interlocked in directions close to each other, and the document placed on the document placing unit 11 is sandwiched in a direction perpendicular to the transport direction 112 to place the placed document. It is possible to correct the inclination of the original document with respect to the conveyance direction 112.

  Here, a position detection circuit 17 </ b> A for detecting the position of the tilt regulating member 17 in a direction perpendicular to the transport direction 112 is incorporated in the lift member 113. For example, the position detection circuit 17A has a plurality of electrical terminals in a direction perpendicular to the transport direction 112, and any one of the plurality of electrical terminals is a metal plate provided on the bottom surface of the tilt regulating member 17; When contacted, the electrical signal corresponding to the position of the electrical terminal in contact with the metal plate is configured to be output to the control unit 5. The control unit 5 can detect the position of each tilt regulating member 17, that is, the width of the document placed on the lift member 113 based on the electrical signal input from the position detection circuit 17 </ b> A. .

  The document detection sensors 18A and 18B are provided in the document placement unit 11 as shown in FIG. 4, and can detect the presence or absence of a document at the arrangement position. Specifically, the document detection sensor 18A is disposed in the vicinity of the center of the end of the lift member 113 on the transport direction 112 side. The document detection sensor 18B is disposed at a position separated from the position where the document detection sensor 18A is disposed by a predetermined distance in the direction opposite to the conveyance direction 112. Specifically, the document detection sensor 18B is disposed at a position that is not covered by an A4 size document placed on the document placement unit 11 with its longitudinal direction set in a direction perpendicular to the transport direction 112. For example, the document detection sensors 18A and 18B are reflection type optical sensors having a light emitting part and a light receiving part. The document detection sensors 18A and 18B each output an electrical signal corresponding to the presence or absence of a document to the control unit 5.

  By the way, when a sheet such as a document is conveyed by a sheet conveying apparatus such as the ADF 1, a conveying sound is generated by the conveying roller 12 or the like. For example, when a sheet having a high rigidity such as thick paper is conveyed by the sheet conveying apparatus, a large conveying sound is generated. On the other hand, a technique is known in which the stiffness of a conveyed sheet is detected and the sheet conveyance speed is controlled according to the detection result. However, even when a sheet having low rigidity is conveyed by the sheet conveying apparatus, for example, when the sheet conveying apparatus is used in a quiet environment, there is a possibility that the sound of conveying the sheet may be heard as a large noise. On the other hand, conveying sound is suppressed by slowing the sheet conveying speed in the sheet conveying apparatus. However, if the sheet conveyance speed is slowed down, the time required to read an image from a large amount of originals becomes long. That is, there is a trade-off relationship between the suppression of the conveyance sound and the speeding up of the image reading. On the other hand, in the image forming apparatus 10, as described below, it is possible to achieve a good balance between suppression of sheet conveyance sound and high-speed image reading.

  Specifically, a conveyance speed control program for causing the CPU to execute a conveyance speed control process (see FIGS. 5 and 6) described later is stored in advance in the ROM or the EEPROM of the control unit 5. The transport speed control program is recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and is read from the recording medium and installed in a storage unit such as the EEPROM of the control unit 5. It may be a thing.

  As shown in FIG. 2, the control unit 5 includes a document detection unit 51, a number detection unit 52, a size detection unit 53, a conveyance unit 54, a conveyance speed control unit 55, and a condition change unit 56. The control unit 5 uses the CPU to execute the conveyance speed control program stored in the ROM, so that the document detection unit 51, the number detection unit 52, the size detection unit 53, the conveyance unit 54, functions as the conveyance speed control unit 55 and the condition change unit 56. Here, the number detection unit 52 is an example of a number detection unit, and the size detection unit 53 is an example of a size detection unit. Moreover, the said conveyance part 54 is an example of a conveyance means, and the said conveyance speed control part 55 is an example of a conveyance speed control means. Furthermore, the condition changing unit 56 is an example of a condition changing unit.

  The document detection unit 51 detects the presence or absence of a document placed on the document placement unit 11. Specifically, the document detection unit 51 detects the presence or absence of a document based on an electrical signal output from the document detection sensor 18A.

  The number detection unit 52 detects the number of documents placed on the document placement unit 11. Specifically, the number detection unit 52 detects the distance from the arrangement position of the distance detection sensor 16 to the bottom surface on the other end side of the lift member 113 based on the electrical signal output from the distance detection sensor 16. To do. The number detection unit 52 refers to the first table data indicating the correspondence between the distance and the number of documents stored in advance in a storage unit such as the EEPROM based on the detected distance. The number of documents can be acquired. Note that the method of detecting the number of documents placed on the document placement unit 11 is not limited to the above, and other known methods may be used.

  The size detecting unit 53 detects the size of the document placed on the document placing unit 11. Specifically, the size detection unit 53 detects the width of the document based on the electrical signal output from the position detection circuit 17A. Then, the size detection unit 53 refers to the second table data indicating the correspondence between the document width and the document size stored in advance in the storage unit such as the EEPROM based on the detected document width. Thus, the size of the document can be acquired. Note that there may be a plurality of document sizes acquired from the width of the document, such as A3 size landscape and A4 size portrait. In this case, the size detection unit 53 determines the size of the document placed on the document placement unit 11 from the obtained plurality of document sizes based on the electrical signal output from the document detection sensor 18B. Identify.

  The transport unit 54 can continuously transport a plurality of documents from the document placing unit 11 to the paper discharge unit 14. Specifically, the transport unit 54 controls driving of the motor that rotates the transport roller 12 to transport a document at a predetermined speed. For example, the transport unit 54 transports a document based on a transport speed set by being stored in a predetermined storage area of the RAM.

  The conveyance speed control unit 55 gradually increases the conveyance speed of the document continuously conveyed by the conveyance unit 54 from a predetermined first speed V1 to a second speed V2. Here, the second speed V2 is an upper limit value of the reading speed (conveying speed) when the image of the original conveyed by the ADF 1 is read at the maximum resolution, for example, at the initial shipment stage of the image forming apparatus 10 or the like. The speed is set in advance in the storage unit such as the EEPROM. The first speed V1 is a speed set in advance in a storage unit such as the EEPROM as a speed slower than the second speed V2.

  Specifically, the transport speed control unit 55 increases the transport speed every time the number of documents continuously transported by the transport unit 54 increases by a predetermined number. For example, the transport speed control unit 55 sets the transport speed to the first speed V1 and starts the transport of the document to the transport unit 54. Each time the number of transported documents increases by five, It is conceivable to add the increment X1 to the transport speed. The conveyance speed control unit 55 acquires the number of conveyed documents based on the electrical signal output from the passage detection sensor 15.

  The transport speed control unit 55 fixes the transport speed to the first speed V1 when the number of documents detected by the sheet number detection unit 52 is equal to or less than a predetermined first threshold value, and the first speed V1. If it exceeds one threshold, the transport speed is gradually increased from the first speed V1 to the second speed V2. On the other hand, the transport speed control unit 55 fixes the transport speed to the second speed V2 when the number of documents detected by the sheet number detection unit 52 exceeds a predetermined second threshold value, and the second speed V2. If it is less than or equal to the threshold, the transport speed is gradually increased from the first speed V1 to the second speed V2. For example, the first threshold value may be 10 sheets and the second threshold value may be 50 sheets.

  Further, the transport speed control unit 55 changes the first speed V1 according to the size of the original detected by the size detection unit 53. Specifically, the transport speed control unit 55 is configured to reduce the first speed V1 so that the transport speed becomes slow when the size of the document detected by the size detection unit 53 is equal to or larger than a predetermined size. To change. For example, when the size of the document detected by the size detection unit 53 is B4 size or more and the first speed V1 is set as the transport speed, the third speed V3 that is slower than the first speed V1. May be set as the set speed instead of the first speed V1. It is also conceivable that the transport speed control unit 55 changes the second speed V2 or the rate of increase in speed so that the transport speed becomes slow instead of the first speed V1. In addition, the transport speed control unit 55 changes one or more of the first speed V1, the second speed V2, and the rate of increase of the speed so that the transport speed becomes slower. May be.

  The condition changing unit 56 controls the first speed V1, the second speed V2, the rate of increase of the transport speed by the transport speed control unit 55, the first threshold value, the second threshold value, and the specific size. The display unit 6 can be changed according to a user operation. Here, the increase rate of the transport speed is the number of transported documents between the increment X1 and the increment X1 until the next addition. For example, the condition changing unit 56 sets the first speed V1 or the like when an operation input for changing the setting of the first speed V1 or the like is performed on the operation display unit 6 by the user. A setting screen is displayed on the operation display unit 6. Then, the condition changing unit 56 changes the first speed V1 and the like according to an input operation on the display screen by the user.

[Conveying speed control processing]
Hereinafter, with reference to FIGS. 5 and 6, an example of a procedure of a conveyance speed control process executed by the control unit 5 according to the conveyance speed control program in the image forming apparatus 10 will be described. Here, steps S11, S12,... Represent the numbers of processing procedures (steps) executed by the control unit 5.

<Step S11>
First, in step S <b> 11, the control unit 5 determines whether or not a document is placed on the document placement unit 11. Specifically, the control unit 5 detects the presence or absence of a document based on an electrical signal output from the document detection sensor 18A. Here, the process of step S <b> 11 is executed by the document detection unit 51 of the control unit 5.

  If the control unit 5 determines that a document is placed on the document placement unit 11 (Yes in S11), the process proceeds to step S12. If no document is placed on the document placement unit 11 (No side of S11), the control unit 5 waits for a document to be placed on the document placement unit 11 in step S11. .

<Step S12>
In step S <b> 12, the control unit 5 detects the size of the document placed on the document placement unit 11. Specifically, the control unit 5 detects the width of the document based on the electrical signal output from the position detection circuit 17A, and refers to the second table data based on the detection result to determine the size of the document. get. In addition, when the sizes of a plurality of documents are acquired, the control unit 5 specifies the size of the document based on the electrical signal output from the document detection sensor 18B. Here, the process of step S12 is executed by the size detection unit 53 of the control unit 5.

<Step S13>
In step S <b> 13, the control unit 5 detects the number of documents placed on the document placement unit 11. Specifically, the control unit 5 controls the driving unit to rotate the lift member 113 to a position where a document placed on the lift member 113 pushes up the pickup roller 114. Then, the control unit 5 detects the distance from the arrangement position of the distance detection sensor 16 to the bottom surface on the other end side of the lift member 113 based on the electrical signal output from the distance detection sensor 16, and the detection result The number of originals is acquired by referring to the first table data based on the above. Here, the process of step S13 is executed by the number detection unit 52 of the control unit 5.

<Step S14>
In step S <b> 14, the control unit 5 determines whether or not the document placed on the document placement unit 11 has been taken out. Specifically, the control unit 5 detects the presence or absence of a document based on an electrical signal output from the document detection sensor 18A. Here, the process of step S <b> 14 is performed by the document detection unit 51 of the control unit 5.

  Here, when the control unit 5 determines that the document placed on the document placement unit 11 has been taken out (Yes in S14), the process proceeds to step S11. If the document placed on the document placement unit 11 has not been taken out (No side of S14), the control unit 5 shifts the process to step S15.

<Step S15>
In step S <b> 15, the control unit 5 determines whether or not the user has performed an operation of performing image reading processing on the document placed on the document placement unit 11 with respect to the operation display unit 6.

  Here, if the said control part 5 judges that the said execution operation was performed with respect to the said operation display part 6 (Yes side of S15), a process will be transferred to step S16. If the execution operation is not performed on the operation display unit 6 (No side in S15), the control unit 5 shifts the process to step S14 and places the operation on the document placement unit 11. The execution operation on the operation display unit 6 is awaited until the finished document is taken out.

<Step S16>
In step S <b> 16, the control unit 5 determines whether or not the number of documents acquired in step S <b> 13 exceeds 50 sheets set as the second threshold value.

  If the control unit 5 determines that the number of documents exceeds 50 (Yes in S16), the process proceeds to step S161. If the number of documents does not exceed 50 (No in S16), the control unit 5 shifts the process to step S17.

<Step S161>
In step S161, the control unit 5 sets the transport speed to the second speed V2. That is, when the number of documents placed on the document placement unit 11 is large, the time required for reading the document image becomes long. Therefore, in the conveyance speed control process, when the number of documents placed on the document placement unit 11 exceeds the second threshold, priority is given to speeding up image reading over suppression of conveyance sound, The conveyance speed is fixed to the second speed V2. Thus, the time required for the image reading process when the number of documents placed on the document placement unit 11 is large is shortened. Here, the process of step S161 is executed by the transport speed controller 55 of the controller 5.

<Step S17>
In step S17, the control unit 5 determines whether or not the size of the document acquired in step S12 is equal to or larger than the B4 size set as the specific size.

  Here, when the control unit 5 determines that the size of the document is equal to or larger than the B4 size (Yes side of S17), the process proceeds to step S171. On the other hand, if the size of the document is not equal to or larger than the B4 size (No in S17), the control unit 5 moves the process to step S18.

<Step S171>
In step S171, the control unit 5 sets the transport speed to the third speed V3. That is, when a large-size document is conveyed by the ADF 1, the conveyance sound becomes larger than that of a small-size document. Therefore, in the conveyance speed control process, when the size of the document placed on the document placement unit 11 is equal to or larger than the specific size, priority is given to suppression of conveyance sound over speeding up of image reading. The initial speed of the conveyance speed is set to the third speed that is slower than the first speed V1. Thereby, the conveyance sound when a large document is conveyed by the ADF 1 is suppressed. Here, the process of step S <b> 171 is executed by the transport speed controller 55 of the controller 5.

<Step S18>
In step S18, the control unit 5 sets the transport speed to the first speed V1. Here, the process of step S18 is executed by the transport speed control unit 55 of the control unit 5.

<Step S19>
In step S19, the control unit 5 determines whether or not the number of documents acquired in step S13 is 10 or less set as the first threshold value.

  If the control unit 5 determines that the number of documents is 10 or less (Yes in S19), the process proceeds to step S191. If the number of documents is not less than 10 (No in S19), the control unit 5 shifts the process to step S20.

<Step S191>
In step S191, the control unit 5 sequentially conveys the document placed on the document placement unit 11 at the conveyance speed, and causes the image reading unit 2 to read the image data of the document. Here, the control unit 5 changes the light amount of the LED light source 221 irradiated on the document when reading the image data in accordance with the conveyance speed. Specifically, when the transport speed is the first speed V1 or the third speed V3, the control unit 5 determines the amount of light emitted from the LED light source 221 and the transport speed is the second speed. In the case of the speed V2, it controls so that it may become smaller than the light quantity of the light irradiated from the said LED light source 221. FIG. As a result, the amount of light reflected by the original and received by the CCD 26 is maintained at a constant level regardless of the change in the irradiation time of the light with respect to one line in the main scanning direction of the original by changing the transport speed. It becomes possible to do. Then, after the reading of the document image placed on the document placement unit 11 is completed, the control unit 5 shifts the processing to step S11. Here, the process of transporting the document in step S191 is executed by the transport section 54 of the control section 5.

  Here, when the transport speed is set to the first speed V1 in the step S18, the transport speed is fixed to the first speed V1 and the image of the document is read. That is, when the number of documents placed on the document placement unit 11 is small, the time required for reading the document image is short. Therefore, in the conveyance speed control process, when the number of documents placed on the document placement unit 11 is equal to or less than the first threshold value, priority is given to suppression of conveyance sound over speeding up of image reading. The conveyance speed is fixed to the first speed V1. Thereby, the conveyance sound generated in the ADF 1 when the number of documents placed on the document placement unit 11 is small is suppressed.

<Step S20>
In step S20, the control unit 5 executes a stage control process described below. And the said control part 5 makes a process transfer to said step S11, after the said step control process is complete | finished.

[Step control processing]
Here, an example of the procedure of the step control process executed in step S20 of the transport speed control process will be described with reference to FIG.

<Step S31>
First, in step S31, the control unit 5 conveys one document placed on the document placing unit 11 at the carrying speed, and causes the image reading unit 2 to read the image data of the document. The controller 5 conveys the document at the first speed V1 (or the third speed V3) until the conveyance speed is first increased in step S34 described later. Moreover, the said control part 5 changes the light quantity of the light irradiated from the said LED light source 221 according to the said conveyance speed similarly to said step S191 of the said conveyance speed control process. Here, the process of step S31 is an example of the first step. Further, the process of transporting the document in step S31 is executed by the transport unit 54 of the control unit 5.

<Step S32>
In step S <b> 32, the control unit 5 determines whether all of the documents placed on the document placing unit 11 have been conveyed. Specifically, the control unit 5 detects the presence or absence of a document based on an electrical signal output from the document detection sensor 18A. Here, the process of step S <b> 32 is executed by the document detection unit 51 of the control unit 5.

  Here, when the control unit 5 determines that all of the document has been conveyed (Yes in S32), the control unit 5 ends the step control process. If all the originals are not conveyed (No side of S32), the control unit 5 shifts the process to step S33.

<Step S33>
In step S33, the control unit 5 determines whether or not the number of conveyed documents is a multiple of five. Specifically, the control unit 5 counts the number of conveyed documents based on the electrical signal output from the passage detection sensor 15 and determines whether or not the counted number is a multiple of 5. .

  If the controller 5 determines that the number of conveyed documents is a multiple of 5 (Yes in S33), the process proceeds to step S34. If the number of conveyed documents is not a multiple of 5 (No in S33), the control unit 5 shifts the process to step S31 and causes the image reading unit 2 to read the next document.

<Step S34>
In step S34, the control unit 5 adds the increment X1 to the transport speed. That is, in the step control process, the increment X1 is added to the conveyance speed every time five sheets of originals are conveyed. Therefore, the conveyance speed gradually increases from the first speed V1 (or the third speed V3) as the initial speed. Here, the process of step S <b> 34 is an example of a second step, and is executed by the transport speed controller 55 of the controller 5.

<Step S35>
In step S35, the control unit 5 determines whether or not the transport speed is equal to or higher than the second speed V2.

  Here, if the said control part 5 judges that the said conveyance speed is more than the said 2nd speed V2 (Yes side of S35), it will transfer a process to step S36. If the transport speed is not equal to or higher than the second speed V2 (No in S35), the control unit 5 moves the process to step S31 and causes the reading control unit 2 to read the next document.

<Step S36>
In step S36, the control unit 5 sequentially conveys the document remaining on the document placement unit 11 at the conveyance speed, and causes the image reading unit 2 to read the image data of the document. When the conveyance speed exceeds the second speed V2 in step S34, the controller 5 resets the conveyance speed to the second speed V2 and conveys the document. . Then, after the reading of the document image placed on the document placement unit 11 is finished, the control unit 5 finishes the step control process. Here, the process of conveying the document in step S36 is executed by the conveyance unit 54 of the control unit 5.

  The first speed V1, the second speed V2, the increase rate of the transport speed, the first threshold value, the second threshold value, and the specific size used in the transport speed control process are the operation display unit 6 By performing the setting operation for, the user can arbitrarily change. Specifically, the control unit 5 sets the first speed V1 and the like when an operation input for changing the setting of the first speed V1 and the like is performed on the operation display unit 6 by the user. The setting display screen is displayed on the operation display unit 6. And the said control part 5 changes said 1st speed V1 etc. according to input operation in the said setting screen by a user. Here, the above process is executed by the condition changing unit 56 of the control unit 5.

  In addition, when the user sets the document conveyance speed in the image reading process on the operation display unit 6 in advance or in the middle of the image reading process, the conveyance speed control in the conveyance speed control process is performed. Regardless, it is conceivable that the document is conveyed at the conveyance speed set by the user. As a result, the document can be conveyed at the conveyance speed reflecting the user's intention.

  As described above, in the transport speed control process, the transport speed of the document transported by the ADF 1 is gradually increased from the first speed V1 toward the second transport speed V2. For this reason, it is possible to achieve a good balance between the suppression of the conveyance sound of the document and the speeding up of the image reading.

  In the transport speed control process, the increment X1 is added to the transport speed every time a predetermined number of sheets are transported. Therefore, the increase in the transport speed from the first speed V1 to the second speed V2 can be realized with a simple process.

  In the transport speed control process, it may be considered as another embodiment that the transport speed is increased every time a predetermined time elapses. For example, the time may be 10 seconds. Even with such a configuration, an increase in the transport speed from the first speed V1 to the second speed V2 can be realized by a simple process.

  In the transport speed control process, when the detected document size is equal to or smaller than a predetermined size, any one of the first speed V1, the second speed V2, and the speed increase rate is selected. Alternatively, it is conceivable as another embodiment that a plurality is changed so that the conveyance speed is increased. Accordingly, it is possible to achieve a balance between suppression of the conveyance sound of the original and speeding up of the image reading in accordance with the size of the original conveyed by the ADF 1.

  Incidentally, the application example of the present invention is not limited to the automatic document feeder such as the ADF 1 of the image forming apparatus 10. For example, the present invention can also be applied to a transport unit for printing paper or the like in the image forming unit 3 of the image forming apparatus 10.

1: ADF
11: Document placement unit 12: Conveying roller 13: Document pressing unit 14: Paper discharge unit 15: Passage detection sensor 16: Distance detection sensor 17: Inclination regulating member 18A, 18B: Document detection sensor 2: Image reading unit 3: Image formation Unit 4: paper feeding unit 5: control unit 51: document detection unit 52: number of sheets detection unit 53: size detection unit 54: conveyance unit 55: conveyance speed control unit 56: condition change unit 6: operation display unit 10: image forming apparatus

Claims (8)

Conveying means capable of continuously conveying a plurality of sheets from the sheet placing section to the sheet discharging section;
Each time the number of sheets continuously conveyed by the conveying means increases by a predetermined number or every time a predetermined time elapses, the sheets continuously conveyed by the conveying means A transport speed control means for increasing the transport speed by a predetermined increment from a predetermined first speed to a second speed;
A sheet number detecting means for detecting the number of sheets placed on the sheet placing section;
Size detecting means for detecting the size of the sheet placed on the sheet placing portion;
Equipped with a,
The transport speed control means fixes the transport speed of the sheet by the transport means at the first speed when the number of sheets detected by the number detection means is equal to or less than a predetermined first threshold; When the first threshold value is exceeded, the conveyance speed of the sheet by the conveyance means is increased from the first speed to the second speed, and the increment is increased according to the size of the sheet detected by the size detection means. change,
In the case where the increase is greater than or equal to a predetermined specific size, the size of the sheet detected by the size detection means is less than the specific size. Smaller sheet conveying device than in some cases . When the number of sheets detected by the number detection unit exceeds a predetermined second threshold, the conveyance speed control unit fixes the sheet conveyance rate by the conveyance unit at the second speed, and the second 2. The sheet conveying apparatus according to claim 1 , wherein the sheet conveying speed of the conveying unit is increased from the first speed to the second speed when the value is equal to or less than a threshold value. 3. The sheet conveyance according to claim 1, wherein the conveyance speed control unit changes one or both of the first speed and the second speed in accordance with a sheet size detected by the size detection unit. apparatus. The conveying speed control means when the size of the sheet detected by said size detecting means is the specific size or more, the first speed as the conveying speed is reduced, and any of the second speed whereas Or the sheet conveying apparatus in any one of Claims 1-3 which changes both . Operation means for accepting user operations;
Condition change that can change any one or more of the first speed, the second speed, the increment , the first threshold, the second threshold, and the specific size according to a user operation on the operation means Means,
Further comprising a sheet conveying apparatus according to claim 1 a. An image reading apparatus comprising: the sheet conveying apparatus according to claim 1 ; and an image reading unit capable of reading image data from a sheet conveyed by the sheet conveying apparatus. An image forming apparatus comprising: the image reading apparatus according to claim 6 ; and an image forming unit capable of forming an image based on read image data read by the image reading apparatus. A sheet conveying method in a sheet conveying apparatus,
A first step of starting conveyance of the sheet from the sheet placement unit to the sheet discharge unit at a first predetermined speed;
Each time the number of sheets continuously conveyed in the first step increases by a predetermined number or every time a predetermined time elapses, the sheet conveyance speed is changed from the first speed in advance. A second step of increasing by a predetermined increment toward a predetermined second speed;
A third step of detecting the number of sheets placed on the sheet placement unit;
A fourth step of detecting the size of the sheet placed on the sheet placement unit;
Only including,
In the second step, when the number of sheets detected in the third step is equal to or less than a predetermined first threshold value, the sheet conveyance speed is fixed to the first speed, and the first threshold value is set. When exceeding, the conveyance speed of the sheet is increased from the first speed to the second speed, and the increment is changed according to the size of the sheet detected by the fourth step,
In the case where the increase is greater than or equal to a predetermined specific size determined in the fourth step, the size of the sheet detected in the fourth step is less than the specific size. Smaller sheet conveyance method than in some cases .

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