JP4595661B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus, and more particularly to an image reading apparatus and an image forming apparatus that move and read a document.

  An image reading apparatus or an image forming apparatus that optically reads an original as an image performs image reading processing by applying light to the original and inputting the reflected light to an image sensor such as a CCD sensor. Image reading apparatuses are generally classified into a stationary document image reading apparatus and a moving document image reading apparatus. The document stationary image reading apparatus performs optical scanning by moving an optical unit for performing image reading processing with respect to a stationary document. The document movement type image reading apparatus performs optical scanning by arranging an optical unit at a predetermined position and moving the document with respect to the optical unit.

  The document movement type image reading apparatus includes a document table glass, and the document moves on the document table glass. A light source that emits light and an image sensor are disposed below the platen glass. The light from the light source is applied to the document via the document table glass. Then, the reflected light is input to the image sensor via the platen glass.

  Therefore, if foreign matter such as dust, dust, and dirt adheres to the platen glass, the image read by the image sensor has a streak line (hereinafter also referred to as streak noise) due to the influence of the foreign matter. Image quality is degraded.

Therefore, a technique for suppressing streak noise by moving the original platen glass at the same time as moving the original in the original moving type image reading apparatus is disclosed in Japanese Patent Application Laid-Open No. 2000-324312 (Patent Document 1). Yes.
JP 2000-324312 A

  However, with the technique disclosed in Japanese Patent Application Laid-Open No. 2000-324312 (Patent Document 1), it is difficult to read a document with sufficient image quality when a region with foreign matter on the platen glass exceeds a predetermined region. Such a problem occurs.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an image reading apparatus capable of reading a high-quality image.

  Another object of the present invention is to provide an image forming apparatus capable of forming a high-quality image.

  In order to solve the above-described problems, according to one aspect of the present invention, an image reading apparatus that moves a transparent member that transmits reflected light from a document when reading the document according to conveyance of the document when reading the document is provided. The transparent member is reverse to the predetermined direction with respect to the original conveying portion for conveying the image in a predetermined direction at a variable speed and the used transmitting portion for transmitting the reflected light among the transmitting portion of the transparent member. A drive unit for moving in a direction at a set moving speed, and a document for reading a document being conveyed based on reflected light transmitted through a transparent member moving at the set moving speed at the time of reading the document A reading unit, a used part setting unit for setting a used transparent part, a speed setting unit for setting a transport speed at which the document transport unit transports the document, and a moving speed of the transparent member, and a movement of the transparent member Speed Is provided with a moving speed determining means for determining whether or not the moving speed of the transparent member is lower than the predetermined moving speed. The document conveyance speed is reset so that the relative speed based on the document conveyance speed and the moving speed of the transparent member is equal to or higher than a predetermined speed.

  Preferably, the predetermined speed is a relative speed based on a document transport speed and a predetermined movement speed.

  Preferably, the use part setting unit sets the use transmission part based on a part where a foreign matter having a predetermined size or more does not exist among the transmission parts of the transparent member.

  Preferably, the document reading unit includes a magnification changing unit that changes a magnification for reading the document based on a ratio between the conveyance speed initially set by the speed setting unit and the reset conveyance speed.

  Preferably, the speed setting means includes a conveyance speed setting means for setting a conveyance speed at which the document conveyance unit conveys the document, and a movement speed setting means for setting the movement speed of the transparent member, and the transparent member Is determined to be lower than the predetermined moving speed, the original conveying speed is reset so that the relative speed between the original conveying speed and the transparent member moving speed is equal to or higher than the predetermined speed. Reset instruction transmission means for transmitting a reset instruction for setting to the transport speed setting means, information on the transport speed reset from the transport speed setting means, and information on timing for resetting the transport speed And an information receiving means for receiving the information, and the moving speed setting means synchronizes the moving speed of the transparent member in synchronization with the timing for resetting the conveying speed based on the reset conveying speed information. The driving unit moves the transparent member based on the reset moving speed of the transparent member, and the magnification changing unit synchronizes with the timing for resetting the transport speed based on the reset transport speed information. The magnification for reading the original is changed.

  According to another aspect of the present invention, an image forming apparatus that moves a transparent member that transmits reflected light from a document when the document is read according to the conveyance of the document when the document is read. The moving speed that is set in the direction opposite to the predetermined direction is set for the transparent part of the original conveying part for conveying the light and the used transmissive part for transmitting the reflected light among the transmissive part of the transparent member. A drive unit for moving the document, a document reading unit for reading the document being transported based on the reflected light that is transmitted through the transparent member that is moving at the set moving speed at the time of document reading, and a use transmitting part. The used part setting means for setting, the speed setting means for setting the transport speed at which the document transport section transports the document, and the moving speed of the transparent member, and the moving speed of the transparent member are higher than the predetermined moving speed. Small Moving speed determining means for determining whether the moving speed of the transparent member is lower than a predetermined moving speed, and the speed setting means Image formation for resetting the document transport speed so that the relative speed based on the moving speed is equal to or higher than a predetermined speed, and forming an image on a predetermined object based on the document information read by the document reading unit The unit is further provided.

  In the image reading apparatus according to the present invention, when it is determined that the moving speed of the transparent member is lower than the predetermined moving speed, the relative speed based on the document conveyance speed and the moving speed of the transparent member is equal to or higher than the predetermined speed. Then, the speed setting means resets the document transport speed. The document transport unit transports the document at the reset transport speed.

  Accordingly, it is possible to prevent the reading quality of the original reading unit from being deteriorated when the moving speed of the transparent member is lower than the predetermined moving speed, and the original reading unit can read a high-quality image. Play.

  In the image forming apparatus according to the present invention, when it is determined that the moving speed of the transparent member is lower than the predetermined moving speed, the relative speed based on the document conveying speed and the moving speed of the transparent member is equal to or higher than the predetermined speed. Then, the speed setting means resets the document transport speed. The document transport unit transports the document at the reset transport speed.

  Accordingly, it is possible to prevent the reading quality of the document reading unit from being deteriorated when the moving speed of the transparent member is lower than the predetermined moving speed, and the document reading unit can read a high-quality image. As a result, the image forming unit has an effect that a high-quality image can be formed on a predetermined object.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

FIG. 1 is a block diagram illustrating an internal configuration of the image forming apparatus 1000.
Referring to FIG. 1, image forming apparatus 1000 includes an automatic document feeder (hereinafter also referred to as ADF) 100, an image reading unit 200, and an image forming unit 400.

  The ADF 100 includes a paper feed tray 110, a paper feed roller 120A, a separation roller 120B, a pre-reading roller 120C, a post-reading roller 120D, a drive pulse motor 150, and a white plate 130.

  A document group 115 is set on the paper feed tray 110. The document group 115 includes a plurality of documents. A document size detection sensor 118 for detecting the size of the document in the sub-scanning direction (hereinafter also referred to as document FD length) is provided on the surface of the sheet feed tray 110. A document passage sensor 119 is provided between the paper feed roller 120A and the separation roller 120B. The document passage sensor 119 determines whether or not a document is passing in front of the sensor.

  The drive pulse motor 150 independently controls the operations of the paper feed roller 120A, the separation roller 120B, the pre-reading roller 120C, and the post-reading roller 120D. Each of paper feed roller 120A, separation roller 120B, and pre-reading roller 120C takes the original set on paper feed tray 110 one by one into ADF 100 under the control of drive pulse motor 150, and reaches the original reading position L1. Rotate to carry.

  The post-reading roller 120D controls the drive pulse motor 150 to perform processing for discharging the document that has passed the document reading position L1 to a discharge stacking tray (not shown) or conveying it to a reverse path for reading the back surface.

  The image reading unit 200 includes a contact glass 210, a reading slider unit 220, mirrors 230A and 230B, a lens 232, an image processing unit 240, a drive pulse motor 250A, and a drive pulse motor 250B.

  The reading slider unit 220 includes an exposure unit 222 and a mirror 224. The drive pulse motor 250B performs control to move the reading slider unit 220 in the left-right direction.

  Drive pulse motor 250A performs control to move contact glass 210 in the left-right direction.

  The contact glass 210 moves in the left-right direction within the range from the reference position L0 to the position L2 under the control of the drive pulse motor 250A when the document is conveyed from the ADF 100.

  The exposure unit 222 has an exposure function. The mirrors 230 </ b> A and 230 </ b> B are arranged to transmit the light received by the mirror 224 to the image processing unit 240 via the lens 232. The image processing unit 240 has a function of converting input light into image data.

  A plurality of documents included in the document group 115 set on the sheet feeding tray 110 is taken into the ADF 100 one by one by the sheet feeding roller 120A, and the document reading position is obtained by the rotation operation of the separation roller 120B and the pre-reading roller 120C. It is conveyed to L1.

  The exposure unit 222 exposes the document from immediately after the document is conveyed to the document reading position L1 until the document passes the document reading position L1. The reflected light from the exposed document is transmitted to the image processing unit 240 through the mirrors 224, 230A, 230B and the lens 232. The image processing unit 240 reads the document as an image by converting the transmitted light into image data. Hereinafter, the process in which the image processing unit 240 reads a document as an image is also referred to as an image reading process.

Image reading unit 200 further includes a reference position detection sensor 260.
The reference position detection sensor 260 detects whether or not the contact glass 210 is at the reference position L0.

  While the image reading process is not performed, the contact glass 210 is stationary at a position where the position of the left end portion of the contact glass 210 is the reference position L0. In the image reading process, the contact glass 210 is controlled to move in the direction opposite to the direction of the document conveyed from the ADF 100 by the drive pulse motor 250A. Specifically, the contact glass 210 is controlled to start moving toward the position L2 in synchronization with the time when the end of the document conveyed from the ADF 100 reaches the document reading position L1. Further, the contact glass 210 is controlled to move by the drive pulse motor 250A so that the position of the right end of the contact glass 210 becomes the position L2 at the time when one document finishes passing the document reading position L1.

  When one document finishes passing through the document reading position L1, the contact glass 210 has the position of the left end of the contact glass 210 as a reference before the time when the end of the next document reaches the document reading position L1. Control is performed to return to a position where the position becomes L0. The contact glass 210 is controlled to move as described above for each image reading process for one original.

  Therefore, by the operation of the contact glass 210, the image processing unit 240 can obtain image data with less noise (for example, streak noise) even if there is a foreign substance such as paper dust or adhesive on the contact glass 210. it can.

  The white plate 130 included in the ADF 100 is disposed so as to cover a part of the range in which the contact glass 210 is movable (for example, a range of positions between the reference position L0 and the positions L1 and L2).

  In general, the speed at which the ADF 100 transports a document (hereinafter also referred to as a document transport speed) is set so as to change relative to the reading speed of the image processing unit 240 based on a setting magnification desired by the user. Here, it is assumed that the user-desired set magnification is, for example, an enlargement ratio of 120% or a reduction ratio of 75%. Based on the set magnification desired by the user and the set document conveyance speed, the image processing unit 240 performs image processing such as enlargement or reduction of image data in the document conveyance direction.

In the image reading process, a speed scaling process or an electronic scaling process is performed.
The speed scaling process is a process of changing the document transport speed in the sub-scanning direction relative to the reading speed of the image processing unit 240 in accordance with a user-set magnification.

  In the electronic scaling process, the document conveyance speed in the sub-scanning direction is set to be the same as the reading speed of the image processing unit 240, and the image data read by the image processing unit 240 is interpolated or thinned based on the set magnification desired by the user. This is a process for enlarging or reducing the image data.

  The image forming unit 400 has a function of performing, for example, a process of printing image data read by the image reading unit 200 on paper (hereinafter also referred to as a printing process). The image forming unit 400 then discharges the printed paper to the outside. The image forming unit 400 may be any device that forms an image on paper based on given data, such as a color laser printer, a monochrome laser printer, or an ink jet printer.

FIG. 2 is a block diagram illustrating an internal control configuration of the image forming apparatus 1000.
Referring to FIG. 2, image forming apparatus 1000 includes ADF 100, image reading unit 200, operation panel unit 300, and image forming unit 400.

  The operation panel unit 300 is attached to, for example, the image reading unit 200 in FIG. Operation panel unit 300 includes panel control unit 370, display unit 310, operation key group 320, and data temporary storage unit 390.

  Panel control unit 370 has a function of performing various types of processing, arithmetic processing, and the like for each unit in operation panel unit 300. The panel control unit 370 includes a microprocessor, an FPGA (Field Programmable Gate Array) which is an LSI (Large Scale Integration) that can be programmed, and an ASIC (Integrated Circuit) designed and manufactured for a specific application. Application Specific Integrated Circuit) or any other circuit having an arithmetic function may be used.

  The display unit 310 has a function of displaying various information to the user as characters, images, and the like. Display unit 310 displays characters or images based on control instructions transmitted from panel control unit 370. The display unit 310 may be any other display device such as a liquid crystal display (LCD (Liquid Crystal Display)), an FED (Field Emission Display), an organic EL display (Organic Electroluminescence Display), or a dot matrix. Good.

  The operation key group 320 is for giving an instruction to the image forming apparatus 1000 by a user's pressing operation. For example, the user inputs the set magnification described above by pressing the operation key group 320. Information input by the operation key group 320 is transmitted to the panel control unit 370.

  The temporary data storage unit 390 is accessed by the panel control unit 370 and used as a work memory for temporarily storing data. The temporary data storage unit 390 is a high-speed RAM (Random Access Memory), SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), SDRAM (Synchronous DRAM), or double data rate mode capable of temporarily storing data. DDR-SDRAM (Double Data Rate SDRAM), which is an SDRAM with an excellent data transfer function, RDRAM (Rambus Dynamic Random Access Memory), DRAM that adopts high-speed interface technology developed by Rambus, and Direct-RDRAM (Direct Rambus Dynamic) Random Access Memory) or any other circuit having a configuration capable of storing and storing data in a volatile manner.

  ADF 100 includes an ADF control unit 170, a motor drive control unit 175, a drive pulse motor 150, a document size detection sensor 118, a document passage sensor 119, and a data temporary storage unit 190.

  The document size detection sensor 118 detects the document FD length of the document group 115 set on the paper feed tray 110 and transmits a document FD length signal indicating the document FD length to the ADF control unit 170.

  The document passing sensor 119 continues to transmit a passing signal to the ADF control unit 170 if the document is passing in front of the sensor.

  The ADF control unit 170 has a function of performing various types of processing, arithmetic processing, and the like for each unit in the ADF 100. Since ADF control unit 170 is similar to panel control unit 370, detailed description will not be repeated. The ADF control unit 170 receives the document FD length signal from the document size detection sensor 118 to acquire the document FD length. The ADF control unit 170 is connected to the motor drive control unit 175 through four signal lines that transmit the excitation signals PA0 to PA3. The ADF control unit 170 sends a control instruction (hereinafter also referred to as a motor control instruction PA) using excitation signals PA0 to PA3 to the motor drive control unit 175.

  The motor drive control unit 175 is connected to the drive pulse motor 150. The motor drive control unit 175 drives the drive pulse motor 150 according to the motor control instruction PA.

  The ADF control unit 170 changes the document conveyance speed in accordance with a user-desired set magnification. Specifically, the ADF control unit 170 outputs a motor control instruction PA for conveying a document at a document conveyance speed (hereinafter also referred to as a set magnification corresponding speed) according to a user-desired set magnification. 175. The motor control instruction PA is a control instruction using excitation signals PA0 to PA3 set at a frequency corresponding to the set magnification corresponding speed.

  The motor drive control unit 175 drives the drive pulse motor 150 according to the motor control instruction PA.

  The drive pulse motor 150 controls the paper feed roller 120A, the separation roller 120B, and the pre-reading roller 120C so that the document is conveyed at a speed corresponding to the set magnification according to the control of the motor drive control unit 175.

  The data temporary storage unit 190 is used as a work memory that is accessed by the ADF control unit 170 and temporarily stores data.

  Since data temporary storage unit 190 is similar to data temporary storage unit 390, detailed description thereof will not be repeated.

  The image reading unit 200 includes a unit controller 270, a motor drive controller 275A, a drive pulse motor 250A, a motor drive controller 275B, a drive pulse motor 250B, an image processor 240, and a reference position detection sensor 260. And a storage unit 290.

  The unit control unit 270 has a function of performing various types of processing, arithmetic processing, and the like for each unit in the image reading unit 200. Since unit control unit 270 is similar to panel control unit 370, detailed description will not be repeated. The unit control unit 270 is connected to the ADF control unit 170 in the ADF 100 through a signal line and can perform data communication.

  The unit control unit 270 transmits information about the set magnification correspondence speed, operation mode information such as single-sided / double-sided mode, control instructions, and the like to the ADF control unit 170 during the image reading process. The ADF control unit 170 receives information on the set magnification corresponding speed, information on the operation mode, a control instruction, and the like, and sends a control instruction corresponding to the control instruction to each unit in the ADF 100.

  Unit control unit 270 is connected to motor drive control unit 275A and four signal lines for transmitting excitation signals U1A0 to U1A3, respectively. Unit control portion 270 sends a control instruction (hereinafter also referred to as motor control instruction U1A) based on excitation signals U1A0 to U1A3 to motor drive control portion 275A. The motor control instruction U1A is a control instruction using excitation signals U1A0 to U1A3 set to a frequency corresponding to the set magnification corresponding speed.

  The motor drive control unit 275A is connected to the drive pulse motor 250A. The motor drive control unit 275A drives the drive pulse motor 250A in response to the motor control instruction U1A.

  Drive pulse motor 250A moves contact glass 210 at a constant speed in the left-right direction under the control of motor drive control unit 275A.

  Unit control unit 270 is connected to motor drive control unit 275B and four signal lines that transmit excitation signals U1B0 to U1B3, respectively. Unit control portion 270 sends a control instruction (hereinafter also referred to as motor control instruction U1B) based on excitation signals U1B0 to U1B3 to motor drive control portion 275B.

  The motor drive control unit 275B is connected to the drive pulse motor 250B. The motor drive control unit 275B drives the drive pulse motor 250B in response to the motor control instruction U1B.

  The drive pulse motor 250B moves the reading slider unit 220 in the left-right direction under the control of the motor drive control unit 275B. In the image reading process using the ADF 100, the reading slider unit 220 is stopped at the document reading position L1.

  Unit control unit 270 is connected to image processing unit 240 and reference position detection sensor 260, and performs data communication.

  The storage unit 290 stores a program for causing the unit control unit 270 and the image processing unit 240 to perform processing to be described later, reading speed data of the image processing unit 240, various other programs and data, and the like. The storage unit 290 is accessed by the unit control unit 270 and the image processing unit 240.

  The storage unit 290 is a hard disk capable of storing a large amount of data. Note that the storage unit 290 is not limited to a hard disk, and may be any medium (for example, a flash memory) that can hold data without being supplied with power.

  That is, the storage unit 290 uses an EEPROM (Erasable Programmable Read Only Memory) that can erase and write the memory any number of times, an EEPROM (Electronically Erasable and Programmable Read Only Memory) that can be electrically rewritten, and ultraviolet rays. Any of a UV-EPROM (Ultra-Violet Erasable Programmable Read Only Memory) capable of erasing and rewriting the stored contents any number of times and a circuit having a configuration capable of storing and storing data in a nonvolatile manner may be used.

  Unit control unit 270 is connected to image forming unit 400. The unit control unit 270 transmits a control instruction for causing the image forming unit 400 to perform a printing process and data necessary for the printing process.

  Upon receiving the control instruction, the image forming unit 400 prints an image corresponding to the received data on paper.

  In the following, an apparatus including the ADF 100, the image reading unit 200, and the operation panel unit 300 is also referred to as an image reading apparatus. In the present invention, among the processes performed by the ADF 100, the image reading unit 200, and the operation panel unit 300, processes that do not use the image forming unit 400 can be realized only by the image reading apparatus.

FIG. 3 is a block diagram illustrating an internal configuration of the image processing unit 240.
Referring to FIG. 3, the image processing unit 240 includes a charge coupled device (CCD) 242, an amplifier unit 243, an A / D conversion unit 244, a shading correction unit 246, and a noise removal processing unit 248.

  The CCD 242 converts the light input from the lens 232 into an electric signal and outputs the electric signal to the amplifier unit 243.

  The amplifier unit 243 amplifies the input electrical signal and outputs the amplified electrical signal to the A / D conversion unit 244.

  The A / D conversion unit 244 converts the input electrical signal into digital data, and outputs the digital data to the shading correction unit 246 during a period in which a shading correction process described later is performed.

  The shading correction unit 246 performs a shading correction process for correcting the sensitivity of the CCD 242 based on the input digital data at the start of use of the image forming apparatus 1000 or at predetermined time intervals.

  The A / D conversion unit 244 outputs the converted digital data to the noise removal processing unit 248 during a period when the shading correction processing is not performed.

  When the image based on the input digital data is an image having noise of a predetermined size or less due to a foreign substance or the like (hereinafter also referred to as a noise-removable image), the noise removal processing unit 248 applies noise to the noise-removable image. Noise is removed by a removal process. Here, the noise removal process is, for example, an image process such as a filter process using data in the peripheral area of the noise part. Thereafter, the noise removal processing unit 248 causes the storage unit 290 to store the image data from which noise has been removed.

  When the image based on the input digital data is an image having noise of a predetermined size or more due to foreign matter or an image having no noise at all, the noise removal processing unit 248 performs noise removal processing to avoid deterioration of the entire image. And the image data is stored in the storage unit 290. In addition, the noise removal processing unit 248 transmits the acquired image data to the unit control unit 270.

  The detection process of foreign matter (hereinafter also referred to as large-size foreign matter) that causes noise of a predetermined size or more is performed during a period not during the image reading process, that is, a period during which the contact glass 210 returns from the position L2 to the reference position L0. It is. In the large foreign matter detection process, an image of the original reading position L1 in the white plate 130 via the contact glass 210 (hereinafter also referred to as a large foreign matter detection image) is input to the image processing unit 240. The image processing unit 240 transmits the input large-size foreign object detection image data to the unit control unit 270. The unit controller 270 can detect the large foreign matter on the contact glass 210 by monitoring the data of the input large foreign matter detection image.

  The position of the large foreign matter on the contact glass 210 is determined by, for example, counting the pulses of the excitation signals U1A0 to U1A3 having the frequency set by the unit control unit 270 to move the contact glass 210 at a desired speed. It can be calculated by

  The unit control unit 270 calculates the position of the large foreign matter on the contact glass 210, and sets the movement region of the contact glass 210 only to the region where the large foreign matter does not exist. As a result, the image noise removal performance can be improved.

  Next, the setting method of the moving speed of the contact glass 210 which is the point of this invention is demonstrated.

FIG. 4 is a view for explaining a method for setting the moving speed of the contact glass 210.
Referring to FIG. 4, FIG. 4A is a diagram illustrating a case where no large-size foreign matter is detected on the contact glass 210 by the large-size foreign matter detection process described above. The glass movement effective length Lg0 (mm) is a width capable of moving the contact glass 210 at the maximum. Note that the data of the glass movement effective length Lg0 is stored in the storage unit 290 in advance. V0 indicates a document conveying speed that is initially set.

In the case of FIG. 4A, the image reading process is performed while the contact glass 210 is moved within the glass movement effective length Lg0. The contact glass 210 is moved by a glass movement effective length Lg0 during a period from the document reading start time to the reading end time (hereinafter also referred to as document reading time). If the length of the document in the sub-scanning direction is L0 (mm) and the reading speed of the image processing unit 240 is V0 (mm / s), the document reading time T0 is calculated by the following equation (1).
T0 (s) = L0 (mm) / V0 (mm / s) (1)
The moving speed of contact glass 210 (hereinafter also referred to as glass moving speed) Vg0 (mm / s) is calculated by the following equation (2).
Vg0 (mm / s) = Lg0 (mm) / T0 (s) (2)
FIG. 4B is a diagram illustrating a case where the large foreign matter 400 is detected on the contact glass 210 by the large foreign matter detection process described above. In this case, image reading processing is performed using a portion on the contact glass 210 where no large foreign matter exists. Therefore, the width that allows the contact glass 210 to be moved at the maximum is set to the glass movement effective length Lg1 (mm) by the unit controller 270.

Before the image reading process is started, the contact glass 210 is moved to the right by the width g1 where the large foreign matter exists under the control of the unit control unit 270. The contact glass 210 is moved by the glass movement effective length Lg1 during the document reading time. In this case, the glass moving speed Vg1 (mm / s) is calculated by the following formula (3).
Vg1 (mm / s) = Lg1 (mm) / T0 (s) (3)
Since Lg1 <Lg0, Vg1 <Vg0.

  FIG. 4C is a diagram illustrating a case where a plurality of large-size foreign matters are detected on the contact glass 210 by the above-described large-size foreign matter detection process. In this case, an image reading process is performed using a portion on the contact glass 210 where a plurality of large foreign matters are not present. Accordingly, the unit controller 270 sets the width in which the contact glass 210 can be moved at the maximum to the glass movement effective length Lg2 (mm).

Before the image reading process is started, the contact glass 210 is moved to the right by a width g2 in which a plurality of large foreign matters are present under the control of the unit control unit 270. The contact glass 210 is moved by the glass movement effective length Lg2 during the document reading time. In this case, the glass moving speed Vg2 (mm / s) is calculated by the following equation (4).
Vg2 (mm / s) = Lg2 (mm) / T0 (s) (4)
Since Lg2 <Lg0, Vg2 <Vg0.

  That is, as the glass movement effective length Lgn becomes smaller, the glass movement speed Vgn becomes slower. When the glass moving speed is slower than a predetermined speed, the speed stability decreases, the vibration of the contact glass 210, noise, and the like become significant.

  FIG. 5 is a graph showing the rate of speed variation with respect to the glass moving speed. The glass moving speed in FIG. 5 is changed by the two-phase excitation method. Here, when the speed fluctuation rate is 10%, for example, even if the glass moving speed is set to 10 (mm / s), the glass moving speed is a speed within a range of 10% (9 to 11 (mm / S)).

  Referring to FIG. 5, the rate of speed fluctuation increases as the glass moving speed decreases. In this case, in order to keep the noise removal performance of the noise removal processing at a predetermined level or higher, the speed variation rate needs to be 60% or lower as an example.

  Therefore, the glass movement effective length Lgn is about 1/4 of the state of FIG. 4A (state of FIG. 4C), and the glass movement speed is less than or equal to the speed Vgs of about ¼ of the initial speed Vg0. Then, the speed variation rate becomes larger than 60%, and the noise removal performance of the noise removal process is lowered below a predetermined level. Hereinafter, the speed Vgs is also referred to as a glass movement limit speed Vgs. When the glass moving speed becomes slower than the glass moving limit speed Vgs, the speed stability decreases, the vibration and noise of the contact glass 210, etc. become remarkable.

  The graph of FIG. 5 is an example, and the characteristics of the graph vary depending on various parameters such as the reading speed of the image processing unit 240, the driving configuration of the contact glass 210, the driving method of the contact glass 210, and the noise removal processing. However, there is no change in the noise removal performance of the noise removal process as the glass moving speed becomes slower.

  When the noise removal performance of the noise removal process is reduced, noise based on a foreign substance smaller than a large foreign substance that can be removed by the noise removal process before the glass moving speed is reduced cannot be completely removed. Therefore, the image processing unit 240 obtains image data in which streak noise is conspicuous. That is, the quality of the image obtained by the image processing unit 240 is degraded.

  Therefore, in order to improve the above problem, in the present invention, when the glass movement effective length Lgn is smaller than the predetermined value Ls, the document conveyance speed is increased. Specifically, when the glass movement speed Vgn becomes smaller than the glass movement limit speed Vgs, the document conveyance speed is increased. That is, the relative speed based on the glass moving speed Vgn and the document conveying speed is kept at a predetermined speed or higher. The predetermined speed is a relative speed based on the document conveyance speed V0 and the glass movement limit speed Vgs. Then, in the image reading process, an electronic scaling process according to the changed document conveyance speed is performed.

  Referring to FIG. 4 again, FIG. 4D shows that the large-size foreign matter is detected on the contact glass 210 by the above-described large-size foreign matter detection process, and the glass moving speed Vgn (mm / s) is FIG. 10 is a diagram showing a state in which the document conveyance speed is increased when the unit control unit 270 sets the glass movement limit speed Vgs (mm / s) or less.

In this case, the document conveyance speed V1 (mm / s) is calculated by the following equation (5).
V1 = V0 × Vgs / Vgn (5)
As a result, the relative speed based on the glass moving speed Vgn and the document conveying speed V1 can maintain a speed necessary for maintaining the noise removal performance of the noise removal processing at a predetermined level or higher. Therefore, the image processing unit 240 has an effect that a high-quality image can be obtained.

  Next, processing (hereinafter also referred to as image forming processing) performed by image forming apparatus 1000 in the present embodiment will be described. The image forming process is a process performed for one JOB (for example, a process of copying 100 originals). The image forming process is performed according to a job start instruction by the user's operation key group 320. The panel control unit 370 causes the data temporary storage unit 390 to store information input by the user operation key group 320.

FIG. 6 is a flowchart of the image forming process.
Referring to FIG. 6, in step S10, unit control portion 270 sets “0” to document number count variable n. Here, the document number count variable n is a variable for counting the number of documents in one JOB. The document number count variable n is stored in the storage unit 290. Thereafter, the process proceeds to step S20.

  In step S20, an initial setting process is performed. In the initial setting process, unit control unit 270 transmits to panel control unit 370 a control instruction for acquiring input information that is stored in data temporary storage unit 390 by the user's operation key group 320 being pressed. In the following, the input information obtained by the user pressing the operation key group 320 is also referred to as user input information. The user input information is, for example, the number of copies, copy density, document set magnification (copy magnification), and the like.

  The panel control unit 370 reads user input information stored in the data temporary storage unit 390 based on the received control instruction, and transmits the user input information to the unit control unit 270. The unit control unit 270 causes the storage unit 290 to store the received user input information. Thereafter, the process proceeds to step S22.

  In step S22, the document conveyance speed V0 is calculated. First, unit control section 270 reads information on the original set magnification (for example, an enlargement ratio of 120%) from the user input information stored in storage section 290. In the following, the information on the set magnification of the document is also referred to as document set magnification information.

  After that, the unit control unit 270 calculates the document conveyance speed V0 based on the document setting magnification information and the reading speed data of the image processing unit 240 stored in the storage unit 290. For example, if the set magnification of the document is 100%, the document conveyance speed V0 is the same as the reading speed of the image processing unit 240. Unit control portion 270 causes storage portion 290 to store the calculated document conveyance speed V0 data. The unit control unit 270 transmits a control instruction for conveying the document to the ADF control unit 170 at the document conveyance speed V0. Based on the control instruction, ADF control unit 170 performs settings for conveying the document at document conveyance speed V0. Thereafter, the process proceeds to step S30.

  In step S30, unit control portion 270 increments document number count variable n by “1”. Thereafter, the process proceeds to step S32.

  In step S32, the nth original is taken in. Specifically, unit control unit 270 transmits to ADF control unit 170 a control instruction for taking in the nth document among a plurality of documents included in document group 115. The ADF control unit 170 transmits a control instruction for taking the nth document to the motor drive control unit 175. In response to the received control instruction, the motor drive control unit 175 operates the paper feed roller 120A to start taking in the nth document. Thereafter, the process proceeds to step S34.

  In step S34, document FD length MLn acquisition processing is performed. In the document FD length MLn acquisition process, the ADF control unit 170 receives the nth document based on the length of time for continuously receiving the passing signal from the document passage sensor 119 based on the nth document that has been captured. The original FD length MLn of the original is determined (acquired). Note that the nth document that has been started to be taken in step S32 temporarily stops at the pre-reading roller 120C. The nth document is conveyed so as to pass the document reading position L1 by the operation of the pre-reading roller 120C after the image reading process of the (n-1) th document is completed. Then, ADF control unit 170 stores data of document FD length MLn in data temporary storage unit 190.

  This document FD length MLn acquisition process is repeated every time one document is fetched. The document FD length acquired by the previous document FD length MLn acquisition process is expressed as ML (n−1).

  Since the process of step S34 is repeated every time one document is taken, if the document FD length MLn is already stored in the data temporary storage unit 190, the ADF control unit 170 determines the old document FD. The newly acquired document FD length MLn is stored, leaving one piece of data of length ML (n−1). That is, the data temporary storage unit 190 stores data of two document FD lengths.

  In the case where two original FD length data are already stored in the data temporary storage unit 190, the ADF control unit 170 adds the newly acquired original FD length MLn data to the old original FD length data. Is overwritten. Thereafter, the process proceeds to step S36.

  In step S36, a conveyance speed change determination process is performed. In the conveyance speed change determination process, it is determined whether or not the document conveyance speed needs to be changed. Specifically, unit control portion 270 determines whether or not document transport speed V0 needs to be changed. Unit control portion 270 determines whether or not latest document FD length MLn is different from document FD length ML (n−1) acquired by the previous document FD length MLn acquisition process. The unit control unit 270 transmits a control instruction for obtaining the document FD length MLn and the document FD length ML (n−1) to the ADF control unit 170, whereby the document FD length MLn and the document FD length ML (n -1) is acquired.

  If the document FD length MLn is different from the document FD length ML (n−1), unit control portion 270 sets the document conveyance speed change flag stored in storage portion 290 to ON. The document transport speed change flag is a flag for determining whether or not to change the document transport speed. When document FD length MLn is different from document FD length ML (n−1), the sizes of the plurality of documents included in document group 115 are not all the same.

  Then, unit control portion 270 calculates the document setting magnification based on the ratio between document FD length MLn and document FD length ML (n−1). For example, when the document FD length MLn is a vertical length of B5 size and the document FD length ML (n−1) is a vertical length of A4 size, the document setting magnification is about 86%. The unit controller 270 calculates the document conveyance speed V0 based on the calculated document setting magnification and the reading speed data of the image processing unit 240 stored in the storage unit 290. The unit controller 270 then replaces the calculated document transport speed V0 with the document transport speed V0 already stored in the storage unit 290.

  The unit control unit 270 transmits a control instruction for conveying the document to the ADF control unit 170 at the document conveyance speed V0. Based on the control instruction, ADF control unit 170 performs settings for conveying the document at document conveyance speed V0.

  As will be described later, when the user has previously made a setting that disables the change of the reading processing mode in the job, the calculated document conveyance speed V0 is stored in the document conveyance already stored in the storage unit 290. Processing to replace the speed V0 is not performed.

  On the other hand, when document FD length MLn and document FD length ML (n−1) are the same, unit control unit 270 sets the document conveyance speed change flag stored in storage unit 290 to OFF. Thereafter, the process proceeds to step S100.

  In step S100, a document conveyance speed changing process, which is a point of the present invention, is performed. The document transport speed changing process is a process for changing the document transport speed. A detailed description of the document conveyance speed changing process will be described later. When the document conveyance speed changing process is completed, the process proceeds to step S200.

  In step S200, the above-described image reading process is performed. A detailed description of the image reading process will be described later. When the image reading process ends, the process proceeds to step S220.

  In step S220, a printout process for printing out the image data obtained by the image reading process is performed. The detailed description of the printout process will be described later. When the printout process ends, the process proceeds to step S240.

  In step S240, the large foreign matter detection process described above is performed. This large foreign matter detection process is repeated every time one document is taken. The large foreign matter detection process is also performed when the image forming apparatus 1000 is turned on. Depending on the frequency of dust on the contact glass 210, the large-size foreign matter detection process is performed every time the image reading process is performed a predetermined number of times so as not to change the glass moving speed unnecessarily. May be performed once.

  In the large foreign matter detection process, as described above, the unit controller 270 calculates the position of the large foreign matter on the contact glass 210 and causes the storage unit 290 to store the position data of the large foreign matter.

  Hereinafter, the position data of the large foreign matter calculated by the previous large foreign matter detection process is also referred to as old large foreign matter position data. Further, the data of the position of the large foreign matter calculated by the detection processing of the large foreign matter at this time is also referred to as new large foreign matter position data.

  Further, since the process of step S240 is repeated every time one document is fetched, if the old large size foreign object position data is already stored in the storage unit 290, the unit control unit 270 determines the old large size. One piece of foreign object position data is left and the newly calculated new large-size foreign object position data is stored. That is, the storage unit 290 stores two large size foreign object position data.

  Note that when two large foreign object position data are already stored in the storage unit 290, the unit controller 270 overwrites and stores the newly calculated large foreign object position data over the old large foreign object position data. Let

  Unit control portion 270 performs the following data comparison process when two large-size foreign object position data are stored in storage portion 290.

  In the data comparison process, the unit control unit 270 determines whether or not the old large foreign matter position data and the new large foreign matter position data are the same. If the old large foreign matter position data and the new large foreign matter position data are not the same, the unit control unit 270 sets the foreign matter position change flag stored in the storage unit 290 to ON. The foreign matter position change flag is a flag indicating that the position data of the large foreign matter has been changed, and the initial value is set to off. Thereafter, the process proceeds to step S250.

  In step S250, it is determined whether there is no document to be captured. Specifically, unit control portion 270 transmits a control instruction for confirming whether there is a document set on paper feed tray 110 to ADF control portion 170. Hereinafter, information indicating whether or not there is a document set on the paper feed tray 110 is also referred to as document presence information. The ADF control unit 170 acquires the document presence information by determining a signal from the document size detection sensor 118 based on the received control instruction, and transmits the document presence information to the unit control unit 270. Through the above processing, the unit control unit 270 determines whether or not there is a document set on the paper feed tray 110.

  If YES in step S250, the image forming process ends. On the other hand, if NO at step S250, the process at step S30 is performed again.

  Next, the document conveyance speed changing process performed in step S100 of the image forming process will be described in detail.

FIG. 7 is a flowchart of the document conveyance speed changing process.
Referring to FIG. 7, in step S102, it is determined whether or not it is necessary to change the document conveyance speed. Specifically, unit control portion 270 determines whether or not the document conveyance speed change flag stored in storage portion 290 is set to ON. If YES in step S102, the process proceeds to step S110. On the other hand, if NO at step S102, the process proceeds to step S104.

  In step S104, unit control portion 270 determines whether or not the glass movement speed change completion flag indicating whether or not the glass movement speed change has been completed is on. The glass movement speed change completion flag is stored in the storage unit 290, and is set to ON or OFF by a process described later. Note that the initial state of the glass movement speed change completion flag is OFF.

  If YES in step S104, the process proceeds to step S106. On the other hand, if NO at step S104, the process proceeds to step S110.

  In step S106, it is determined whether or not the position data of the large foreign matter has been changed. Specifically, unit control portion 270 determines whether or not the foreign object position change flag stored in storage portion 290 is on.

  If YES in step S106, the process proceeds to step S110. On the other hand, if “NO” in the step S106, the document conveying speed changing process is ended, the process returns to the image forming process of FIG. Thus, the image reading process is performed with the currently set glass moving speed, original conveying speed, and original setting magnification unchanged.

  In step S110, the document conveyance speed V0 and the document FD length are acquired. Specifically, unit control portion 270 reads data of document conveyance speed V0 from storage portion 290. Unit control portion 270 also transmits a control instruction for acquiring document FD length MLn to ADF control portion 170. ADF control unit 170 transmits data of document FD length MLn to unit control unit 270 based on the received control instruction. With the above processing, unit control portion 270 acquires document FD length MLn. Thereafter, the process proceeds to step S112.

In step S112, an initial document transport time T0 is calculated. Specifically, unit control portion 270 calculates document conveyance time T0 based on the following equation (6).
T0 = MLn / V0 (6)
Thereafter, the process proceeds to step S114.

  In step S114, the glass movement effective length Lgn is calculated. Specifically, unit control portion 270 calculates glass movement effective length Lgn in which a plurality of large-size foreign matters on contact glass 210 do not exist based on the latest large-size foreign matter position data stored in storage portion 290. To do. The unit control unit 270 stores the calculated glass movement effective length Lgn in the storage unit 290. In addition, when the glass movement effective length Lgn is already stored in the storage unit 290 by the processing of the previous step S114, the unit control unit 270 leaves one piece of data of the old glass movement effective length Lg (n−1). Then, the newly calculated glass movement effective length Lgn is stored. That is, the storage unit 290 stores two pieces of glass movement effective length data.

  In addition, when two pieces of glass movement effective length data are already stored in the storage unit 290, the unit control unit 270 overwrites and stores the data of the glass movement effective length Lgn on the old glass movement effective length data. Let Thereafter, the process proceeds to step S116.

In step S116, the glass movement speed Vgn is calculated. Specifically, unit control portion 270 calculates glass moving speed Vgn based on the following equation (7).
Vgn = Lgn / T0 (7)
The unit control unit 270 stores the calculated glass moving speed Vgn in the storage unit 290. In addition, when the glass moving speed Vg (n−1) is already stored in the storage unit 290 by the process of the previous step S116, the unit control unit 270 stores the data of the old glass moving speed Vg (n−1). One is left and the newly calculated glass movement speed Vgn is stored. That is, the storage unit 290 stores data of two glass moving speeds.

  In addition, when two pieces of glass movement speed data are already stored in the storage unit 290, the unit control unit 270 overwrites and stores the glass movement speed Vgn on the older glass movement speed data. Thereafter, the process proceeds to step S118.

  In step S118, unit control portion 270 sets the glass movement speed change completion flag to OFF. Thereafter, the process proceeds to step S120.

  In step S120, the unit controller 270 determines whether or not the glass movement speed Vgn calculated in step S116 is smaller than the above-described glass movement limit speed Vgs. If YES in step S120, the process proceeds to step S122. On the other hand, if NO at step S120, the process proceeds to step S120A.

  In step S120A, unit control unit 270 performs setting for setting the moving speed of contact glass 210 to glass moving speed Vgn. With this setting, the contact glass 210 is controlled to move at the glass moving speed Vgn.

  In addition, unit control unit 270 performs setting for setting glass movement effective length of contact glass 210 to glass movement effective length Lgn stored in storage unit 290. With this setting, the contact glass 210 is controlled to move with the glass movement effective length Lgn. Thereafter, the process proceeds to step S122A.

  In step S122A, unit control portion 270 sets the glass movement speed change completion flag to ON. Thereafter, the document conveyance speed changing process ends, the process returns to the image forming process of FIG. 6, and the process proceeds to step S200 subsequent to step S100.

  In step S122, a process for changing the document conveyance speed is performed in order to solve the above-described problem when the contact glass 210 is moved at a speed lower than the glass movement limit speed Vgs. Note that the changed document conveying speed is V1.

  Specifically, unit controller 270 calculates document conveyance speed V1 based on the above-described equation (5). The document conveyance speed V1 is a speed at which the relative speed based on the document conveyance speed V1 and the glass movement speed Vgn is equal to or higher than the relative speed based on the document conveyance speed V0 and the glass movement limit speed Vgs. Thereafter, the process proceeds to step S124.

  In step S124, a speed change request is made to ADF 100. Specifically, unit control unit 270 transmits a control instruction for conveying a document to ADF control unit 170 at document conveyance speed V1. Thereafter, the process proceeds to step S130.

  In step S130, unit control portion 270 determines whether or not the ADF 100 side can change the document conveyance speed. First, the unit control unit 270 receives from the ADF control unit 170 an answer to the control instruction transmitted in step S124.

  In actual control, in response to a speed change request to the ADF 100, a sheet passing path configuration in the ADF 100, a configuration of a part for changing the speed, or a speed change processing delay due to a communication processing delay are considered. For this reason, the unit control unit 270 needs to confirm which read original is to be changed in speed and synchronize.

  Accordingly, unit control unit 270 determines that ADF 100 can change the document conveyance speed when it receives information on the number of sheets that can be changed as the document conveyance speed change timing determined on ADF 100 side. The number information that can be changed is information included in the response transmitted from the ADF control unit 170. Here, the number information that can be changed is assumed to be information of m (natural number). In this case, the changeable sheet number information indicates that the ADF 100 can change the document conveyance speed from the mth document in the JOB. When the unit control unit 270 receives information on the number of sheets that can be changed, the ADF control unit 170 conveys the document from the mth document in the JOB based on the control instruction received in step S124. The setting for conveying the speed at V1 has been completed.

  If YES in step S130, the process proceeds to step S132. On the other hand, if NO at step S130, the process proceeds to step S130A.

  In step S130A, a glass movement setting process is performed. In the glass movement setting process, the unit control unit 270 performs setting for setting the moving speed of the contact glass 210 to the glass moving speed Vg (n−1) stored in the storage unit 290. With this setting, the contact glass 210 is controlled to move at the glass moving speed Vg (n−1). In this case, since the change of the glass movement speed is not completed, the glass movement speed change completion flag remains off.

  In addition, unit control unit 270 performs setting for setting the glass movement effective length of contact glass 210 to glass movement effective length Lg (n−1) stored in storage unit 290. With this setting, the contact glass 210 is controlled to move with the glass movement effective length Lg (n−1). Thereafter, the document conveyance speed changing process ends, the process returns to the image forming process of FIG. 6, and the process proceeds to step S200 subsequent to step S100.

  Here, as an example of the case where the process of step S130A is performed, that is, the case where it is impossible to change the document conveyance speed on the ADF 100 side, there is the following case. For example, if the reading processing mode is changed in the job currently being processed, a difference occurs in the image quality of a plurality of documents read in the job. Therefore, a user who desires to keep the image quality of a plurality of originals performs a setting for disabling the change of the reading processing mode in the job by pressing the operation key group 320 in advance.

  In this case, it is impossible to change the document conveyance speed within the JOB. Therefore, the movement of the contact glass 210 is controlled as set in S130A. In this case, the newly detected large foreign matter is subjected to noise removal at a level that is possible only by noise removal processing.

  In step S132, the document number count variable n is referred. Specifically, unit control portion 270 reads document number count variable n stored in storage portion 290. Thereafter, the process proceeds to step S140.

  In step S140, unit control portion 270 determines whether document number count variable n is greater than or equal to m. If YES in step S140, the process proceeds to step S142. On the other hand, if NO at step S140, the process proceeds to step S130A described above.

  In step S142, the electronic zoom mode is set. Specifically, unit control portion 270 turns on an electronic magnification processing flag for performing electronic magnification processing in the image reading processing performed after the document conveyance speed change processing. The electronic scaling processing flag is stored in the storage unit 290. At the time when the process of step S142 is performed, the ADF control unit 170 has completed the setting for conveying the document conveyance speed at V1. Thereafter, the process proceeds to step S144.

In step S144, document setting magnification change processing is performed. In the document setting magnification changing process, the unit control unit 270 calculates the document setting magnification SC1 by substituting the document conveyance speed V0 and the document conveyance speed V1 obtained or calculated in the above-described processing into the following equation (8). To do.
SC1 = V1 / V0 (8)
Unit control portion 270 causes storage portion 290 to store the calculated document setting magnification SC1. Thereafter, the process proceeds to step S146.

In step S146, the glass movement speed Vgn1 is calculated. Specifically, the glass movement speed Vgn is changed to a glass movement speed Vgn1 commensurate with the document conveyance speed V1. First, a document transport time T1 corresponding to the document transport speed V1 is calculated. Specifically, unit control portion 270 calculates document conveyance time T1 by substituting V1 for document FD length MLn and document conveyance speed acquired or calculated in the above-described processing in equation (9) below. .
T1 = MLn / V1 (9)
The unit control unit 270 calculates the glass movement speed Vgn1 by substituting the glass movement effective length Lgn and the document conveyance time T1 acquired or calculated in the above-described processing into the following equation (10).
Vgn1 = Lgn / T1 (10)
Then, unit control unit 270 performs setting for setting the moving speed of contact glass 210 to glass moving speed Vgn1. With this setting, the contact glass 210 is controlled to move at the glass moving speed Vgn1.

  In addition, unit control unit 270 performs setting for setting glass movement effective length of contact glass 210 to glass movement effective length Lgn stored in storage unit 290. With this setting, the contact glass 210 is controlled to move with the glass movement effective length Lgn.

  Therefore, the image reading process is performed at a speed equal to or higher than the glass movement limit speed Vgs using the glass movement effective length Lgn of the portion on the contact glass 210 where no large foreign matter exists.

  Thereby, as above-mentioned, the glass moving speed can maintain speed required in order to keep the noise removal performance of a noise removal process more than a predetermined level. Therefore, in the image reading process, the image processing unit 240 has an effect that a high-quality image can be obtained.

Thereafter, the process proceeds to step S148.
In step S148, unit control portion 270 sets the glass movement speed change completion flag to ON. Thereafter, the document conveyance speed changing process ends, the process returns to the image forming process of FIG.

  In step S200, an image reading process is performed. In the image reading process, the ADF control unit 170 transmits a control instruction for conveying the nth document to the motor drive control unit 175 at the document conveyance speed set in the document conveyance speed changing process. Assume that the set document transport speed is, for example, the document transport speed is V1.

  Based on the received control instruction, the motor drive control unit 175 controls the pre-reading roller 120C so that the nth document passes through the document reading position L1 at the specified document transport speed.

  In synchronization with the passage of the nth original document at the original reading position L1, the unit controller 270 controls the movement of the contact glass 210 at the glass movement speed and the glass movement effective length set in the original conveyance speed changing process. To do.

  Assume that the glass movement speed and the glass movement effective length are, for example, a glass movement speed Vgn1 and a glass movement effective length Lgn, respectively.

  The unit control unit 270 sends a control instruction for performing the movement control to the motor drive control unit 275A. The motor drive control unit 275A operates the drive pulse motor 250A to control the movement of the contact glass 210 based on the received control instruction.

  Further, the following image reading setting process is performed before the nth original is conveyed. In the image reading setting process, the unit control unit 270 determines whether or not the electronic scaling process flag stored in the storage unit 290 is set to ON.

  When the electronic scaling process flag is set to ON, the unit control unit 270 acquires image data by the electronic scaling process based on the document setting magnification SC1 stored in the storage unit 290 in the image processing unit 240. A control instruction for performing processing is transmitted to the image processing unit 240. Based on the received control instruction, the image processing unit 240 performs image data acquisition processing (hereinafter also referred to as electronic scaling acquisition processing) by electronic scaling processing based on the document setting magnification SC1. In the electronic scaling acquisition process, the image processing unit 240 performs image processing such as thinning processing or interpolation processing on the read image data in accordance with the document setting magnification SC1. By this processing, the image processing unit 240 has the same magnification as that at the document conveyance speed V0 even if the document conveyance speed set in the document conveyance speed change process is the document conveyance speed V1 larger than the document conveyance speed V0. There is an effect that data can be acquired.

  Note that the n-th image data read by the image processing unit 240 performing the processing described with reference to FIG. 3 while the n-th document starts to pass through the document reading position L1 and finishes passing. On the other hand, an electronic magnification acquisition process is performed. The image processing unit 240 causes the storage unit 290 to store the image data acquired by the electronic scaling acquisition process.

  With the above processing, the image processing unit 240 has an effect that a high-quality image with less noise can be obtained.

  If the electronic scaling process flag is set to OFF, the image processing unit 240 performs the process described with reference to FIG. 3 without performing the above-described electronic scaling acquisition process, and uses the nth document as image data. Read and store in the storage unit 290. Thereafter, the process proceeds to step S220.

  In step S220, printout processing is performed. In the printout process, unit control unit 270 transmits the control instruction for performing the printing process and the image data stored in storage unit 290 in the process of step S200 to image forming unit 400.

  Upon receiving the control instruction, the image forming unit 400 prints an image corresponding to the received image data on paper.

  As a result of the above processing, when the electronic scaling processing flag is set to ON, the image data received by the image forming unit 400 is a high-quality image with little noise, so the image printed on the paper also has little noise. There is an effect that a high-quality image can be obtained.

  As described above, in the present embodiment, when there are a plurality of large foreign matters on the contact glass 210, image reading is performed using a portion on the contact glass 210 where there are no large foreign matters. Processing is performed. Therefore, the image processing unit 240 has an effect of being able to obtain a high-quality image free from streak noise due to a large foreign object.

  Further, based on a portion on the contact glass 210 where a plurality of large foreign matters do not exist, the glass movement effective length Lgn of the contact glass 210 is set. When the glass movement speed Vgn corresponding to the set glass movement effective length Lgn is smaller than the glass movement limit speed Vgs, the document conveyance speed is increased. Therefore, the relative speed based on the glass moving speed Vgn and the changed document conveying speed can maintain the speed necessary for maintaining the noise removal performance of the noise removal processing at a predetermined level or higher. That is, when the glass movement speed Vgn becomes smaller than the glass movement limit speed Vgs, the glass movement speed Vgn is not changed. As a result, since the movement of the contact glass 210 is controlled at the glass movement speed Vgn, it is possible to prevent vibration noise and the like that are generated when the contact glass 210 is controlled to move at a glass movement speed that is lower than the glass movement speed Vgn. There is an effect that can be done.

  In addition, even if the document conveyance speed is changed, by performing electronic scaling acquisition processing that performs image processing such as thinning processing or interpolation processing according to the changed document conveyance speed, and before the document conveyance speed is changed, There is an effect that an appropriate image of the same magnification can be obtained.

  In this embodiment, when changing the document conveyance speed, unit control unit 270 issues a control instruction to change the document conveyance speed to ADF control unit 170 in ADF 100. A process of changing the glass moving speed in synchronization with the change of the document conveying speed by the ADF control unit 170 is described. However, the present invention can be realized by other processing methods.

  As an example of another processing method, the unit control unit 270 issues a control instruction for changing the document conveyance speed to the ADF control unit 170. Then, the image reading process may be interrupted until the change of the document conveyance speed by the ADF control unit 170 is completed. The ADF 100 resumes the image reading process when the document can be conveyed.

  Further, in the present embodiment, an example will be described in which the ADF control unit 170 in the ADF 100 performs control for conveying a document, and the unit control unit 270 in the image reading unit 200 performs movement control of the contact glass 210. Yes. However, the control for conveying the document and the movement control of the contact glass 210 may be performed by one control unit. For example, the place where the one control unit is provided may be in the ADF 100 or the image reading unit 200. That is, the number and configuration of the control units are arbitrary.

  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.

1 is a block diagram illustrating an internal configuration of an image forming apparatus. 2 is a block diagram showing an internal control configuration of the image forming apparatus. FIG. It is a block diagram which shows the internal structure of an image process part. It is a figure for demonstrating the setting method of the moving speed of contact glass. It is the figure which showed the speed fluctuation rate with respect to the glass moving speed with the graph. It is a flowchart of an image formation process. 10 is a flowchart of document conveyance speed change processing.

Explanation of symbols

  100 ADF, 200 image reading unit, 210 contact glass, 240 image processing unit, 270 unit control unit, 370 panel control unit, 400 image forming unit, 1000 image forming apparatus.

Claims (6)

An image reading apparatus that moves a transparent member that transmits reflected light from the original when the original is read, according to conveyance of the original when reading the original,
A document conveying section for conveying the document in a predetermined direction at a variable speed;
Drive for moving the transparent member in a direction opposite to the predetermined direction at a set moving speed with respect to a used transmissive portion used for transmitting the reflected light among the transmissive portion of the transparent member. And
A document reading unit for reading the document being conveyed based on the reflected light transmitted through the transparent member being moved at the set moving speed at the time of reading the document;
Use part setting means for setting the use transparent part;
Speed setting means for setting the transport speed at which the document transport section transports the document and the moving speed of the transparent member;
A moving speed determining means for determining whether or not the moving speed of the transparent member is lower than a predetermined moving speed;
When it is determined that the moving speed of the transparent member is smaller than the predetermined moving speed, the speed setting means determines that a relative speed based on the document conveying speed and the moving speed of the transparent member is a predetermined speed. An image reading apparatus that resets the conveyance speed of the original so as to achieve the above.   The image reading apparatus according to claim 1, wherein the predetermined speed is a relative speed based on a conveyance speed of the document and the predetermined movement speed.   The image reading apparatus according to claim 1, wherein the use part setting unit sets the use transmission part based on a part where a foreign matter having a predetermined size or more does not exist among transmission parts of the transparent member.   The document reading unit includes a magnification changing unit that changes a magnification for reading the document based on a ratio between a conveyance speed initially set by the speed setting unit and the reset conveyance speed. The image reading apparatus according to 1. The speed setting means includes a transport speed setting means for setting a transport speed at which the document transport section transports the document,
A moving speed setting means for setting the moving speed of the transparent member,
When it is determined that the moving speed of the transparent member is lower than the predetermined moving speed, the relative speed based on the document conveying speed and the moving speed of the transparent member is equal to or higher than a predetermined speed. A reset instruction transmitting means for transmitting a reset instruction for resetting the transport speed of the document to the transport speed setting means;
Information receiving means for receiving information on the reset transport speed and information on timing for resetting the transport speed from the transport speed setting means,
The moving speed setting means resets the moving speed of the transparent member in synchronization with the timing of resetting the transport speed based on the reset transport speed information,
The driving unit moves the transparent member based on the reset moving speed of the transparent member,
The image reading apparatus according to claim 4, wherein the magnification changing unit changes a magnification for reading the document in synchronization with a timing for resetting the conveyance speed based on the reset conveyance speed information. An image forming apparatus that moves a transparent member that transmits reflected light from the original when the original is read in accordance with the conveyance of the original when reading the original;
A document conveying section for conveying the document in a predetermined direction at a variable speed;
Drive for moving the transparent member in a direction opposite to the predetermined direction at a set moving speed with respect to a used transmissive portion used for transmitting the reflected light among the transmissive portion of the transparent member. And
A document reading unit for reading the document being conveyed based on the reflected light transmitted through the transparent member being moved at the set moving speed at the time of reading the document;
Use part setting means for setting the use transparent part;
Speed setting means for setting the transport speed at which the document transport section transports the document and the moving speed of the transparent member;
A moving speed determining means for determining whether or not the moving speed of the transparent member is lower than a predetermined moving speed;
When it is determined that the moving speed of the transparent member is smaller than the predetermined moving speed, the speed setting means determines that a relative speed based on the document conveying speed and the moving speed of the transparent member is a predetermined speed. Reset the document transport speed so that
An image forming apparatus, further comprising: an image forming unit configured to form an image on a predetermined object based on information on a document read by the document reading unit.

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