JP2004193738A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus arranged to detect the bending amount, and the like, of a document based on document forward end detection signals from two sensors, and to control the image reading starting timing. <P>SOLUTION: The image forming apparatus comprises a document mounting means, a means for feeding a document mounted on the document mounting means, a means for carrying the document thus fed toward an image reading position, an image reading means disposed at the image reading position, and an image forming means. The carrying means is disposed in the vicinity of the image reading position and on this side thereof when viewed from the carrying direction of document, and two sensors are provided between the carrying means and the image reading position on the same phase in the direction perpendicular to the carrying direction of document. Bending amount and direction of the document are detected based on the document forward end detection signals from two sensors, and image reading starting timing of the image reading means is controlled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus including an automatic document feeder, such as a copying machine, a printer, and a facsimile.
[0002]
[Prior art]
Exposure (writing) with a laser beam or the like is performed on the surface of the uniformly charged image carrier to form an electrostatic latent image corresponding to the original, and the electrostatic latent image is developed by a developing unit to form a toner image ( A visible image), the toner image is transferred onto a transfer material such as paper by a transfer unit, and the toner image is fixed on the transfer material by heating and pressing using a heating unit. 2. Description of the Related Art An image forming apparatus having a configuration in which an automatic document feeder is attached to an image forming apparatus using an electrophotographic method is widely known.
[0003]
The automatic document feeder separates and feeds the documents stacked (placed) on a document mounting table one by one by a feeder that is driven and controlled in accordance with an image forming process, and performs image reading at an image reading position (image reading unit). ), The original read in the transport state is discharged onto a paper output tray, or when a double-sided image of the original is prepared, the original on which the image of the first side has been read is inverted. Thereafter, the image data is conveyed through the image reading position, and is controlled by a computer so as to be discharged onto the discharge tray.
[0004]
As described above, the automatic document feeder is useful for improving the functions of the image forming apparatus, but on the other hand, there are various factors such as errors in assembling the rollers as the document conveying means, or changes over time of the rollers. However, there is a problem in that the original being transported may bend, and when the original is read by the reading unit, the original is transported in a state inclined with respect to the reference transport direction, so that the finished image becomes difficult to see. Was.
[0005]
In addition, a configuration is generally used in which a signal for starting reading is output to the image forming apparatus main body side from a detection signal obtained by detecting a document at a predetermined position on the transport path with a sensor. It must be provided at a position on the conveyance path that coincides with the center of the document width orthogonal to the conveyance direction.
[0006]
The correction of the document bending in the conveyance path of such an automatic document feeder, and a separation sensor between a separation feeding roller and a first feeding roller pair provided downstream thereof as related to a reading start signal. A skew detection sensor is provided, and both sensors can detect the skew amount of the document; a second feed roller pair is provided downstream of the first feed roller pair; There is known an automatic document feeder which is provided with a post-registration sensor and outputs a document reading start signal to the main body of the copying machine based on detection of the leading edge of the document by the post-registration sensor (see Patent Document 1). .).
[0007]
[Patent Document 1]
JP 2002-199154 A (paragraphs 0051, 0052, 0055, FIG. 2)
However, the configuration in the above-mentioned patent document is a conventionally known configuration in which the skew is corrected by abutting the leading end of a document in a state in which the second feeding roller pair is kept in a rotation stopped state. No consideration has been given to skew that may occur in the transport path.
[0008]
In addition, since the position of the post-registration sensor is far from the reading unit, accurate control is difficult.
[0009]
Further, there is a problem that the structure is further complicated because three sensors are required for detecting the skew amount and controlling the start of reading.
[0010]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and a main object is to provide two sensors in the vicinity of an image reading position in the vicinity of the image reading position, and use the difference between the detection times of the original document leading edge detection signals of the two sensors to detect the original. It is an object of the present invention to provide an image forming apparatus configured to detect a bending (skew) amount and a bending direction and to control a start timing of image reading by an image reading unit.
[0011]
Another object of the present invention is to provide an image forming apparatus which rotates and corrects a read image in accordance with the obtained amount of skew of a document and enables normal image formation.
[0012]
[Means for Solving the Problems]
The object of the present invention can be achieved by the following configurations.
[0013]
(1) Document placement means, paper supply means for feeding a document placed on the document placement means, transport means for transporting the fed document to an image reading position, and image reading In an image forming apparatus having an image reading unit provided at a position and an image forming unit,
The transport unit is provided near the front side of the image reading position when viewed in the transport direction of the document,
Two sensors are provided between the conveyance unit and the image reading position and in the same phase in a direction orthogonal to the conveyance direction of the document, and the document is bent based on the leading edge detection signal of the document by the two sensors. Detecting the amount and the bending direction, and controlling the start timing of image reading by the image reading means,
An image forming apparatus comprising:
[0014]
(2) The image read by the image reading means is subjected to image processing and is taken as image data into a memory, and at least exposure based on the image data read from the memory corrects the bending of the document. The image forming apparatus according to (1), wherein the exposure is performed based on the image data obtained.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus including a digital copying machine.
The image forming apparatus according to the present embodiment forms a toner image on a transfer material using an electrophotographic method, and includes an automatic document feeder (hereinafter, referred to as ADF for convenience of explanation) 1, an image reading device 2, and an image reading device. The image forming apparatus includes a forming unit 3, a transfer material storage unit 4, a paper feed unit 5, a reverse discharge / re-feed unit 6, and a reverse transport unit 8.
[0017]
The ADF 1 includes a document placement unit (hereinafter, referred to as a document placement table) 110 for placing a document, a sheet feeding unit 111 for sending a document placed on the document placement table 110, and a separation (separation) of the sent document. Original separating means 112 for conveying one sheet at a time, a single-sided original registration means 113 controlled to regulate the leading edge of the original separated by the original separation means 112, and the original conveyed by the original registration means 113 Original conveying means 114 (the original feeding means and the original registration means have the function as the original conveying means. However, from the viewpoint of directly relating to the present invention, only this roller pair is used. However, the document is referred to as a document transporting unit (hereinafter, referred to as a document first transporting unit in view of a balance with the document second transporting unit), and the document reading position is interposed therebetween. The document second conveyance means 115 provided at a position substantially corresponding to the first conveyance means 114, the document discharge tray 120, and the document whose image reading based on the content of the image forming instruction is completed is discharged onto the document discharge tray 120. A second discharge unit 116 for feeding paper, a document reversing unit 117 used in a duplex copying mode for forming a double-sided image of a document, and an intermediate conveyance unit 118 are provided.
[0018]
The paper feeding unit 111 is constituted by a single roller, and includes another document separating unit 112, document registration unit 113, document first conveying unit 114, document second conveying unit 115, discharging unit 116, document reversing unit 117. , And the intermediate conveying means 118 are each constituted by a roller pair.
[0019]
Further, the first document conveying means 114 is configured (controlled) so as to function as a document registration means in a double-sided copying mode of the document. At this time, the rotation of the document registration means 113 is controlled as a conveyance roller.
[0020]
In the above-described configuration, a one-way clutch and a plurality of motors including a reversible motor can be attached to appropriate rollers so as not to damage the document to be conveyed, and the drive is controlled by a control unit C described later. It is configured so that:
[0021]
A guide member (guide surface) is provided between each of the means (G and G1 to G7 in FIG. 2) to form a transport path, and a transport path switching member (see FIG. K1, K2) are provided.
[0022]
In the figure, reference numeral 100 at the top of the apparatus main body denotes an operation unit, 101 denotes a start button for starting image formation, and 102 denotes a power switch.
[0023]
When the mode of the image forming apparatus is the one-sided copying mode, the document conveyance path in the ADF is as follows.
[0024]
Note that the configuration including the transport path is specifically shown in FIG. 2 and will be described with reference to FIG.
[0025]
The originals (not shown) stacked on the original placing table 110 are sent out by a paper feeding unit 111, and one original is separated by an original separating unit 112, and is continuously transported.
[0026]
Next, the leading end of the document abuts against the document registration unit 113 that is not rotating to correct the skew of the document.
[0027]
When the document registration means 113 is rotated according to the control of the control means C, the document is directed to the document first conveyance means 114 located below via the back side of the conveyance path switching member K1, and further image reading is performed. It is conveyed toward the position.
[0028]
The image reading position is provided near the downstream side of the first document conveying means 114, and the document image is read by the image reading means (described later) through the slit 21 in which the transparent glass T is embedded.
[0029]
The original at the time of image reading is regulated by the guide member G on the back side of the original and the transparent glass T, and thereafter, is conveyed further downstream under the action of the second original conveying means 115, and the conveyance path switching member K2 The paper advances while being regulated on the abdominal side, and is discharged onto the document discharge table 120 by the discharge means 116.
[0030]
The document conveyance path when the mode of the image forming apparatus is the duplex copying mode is as follows.
[0031]
The original sent out from the original mounting table 110 by the paper feeding unit 111 and separated by the original separating unit 112 is continuously transported downward by the original registration unit 113 which is controlled to rotate, and the transport path switching member K1 The document is directed to the intermediate transport unit 118 under the regulation of the abdomen side, is nipped by the document reversing unit 117 and the intermediate transport unit 118, and is transported by an appropriate length.
[0032]
Next, the rotation of the document reversing means 117 is stopped in a state where the rear end of the document in the conveyance direction is held by the document reversing means 117, and the intermediate conveyance means 118 is again rotated by the reverse rotation of the reversing means 117 immediately after. The document is conveyed to the left via the conveyance path switching member K 1 and reaches the first document conveying means 114.
[0033]
At this time, the first document conveying means 114 is controlled to be in a rotation stop state so as to function as a document registering means. When the leading end of the document comes into contact with the first document conveying means 114, the skew of the document is reduced. Be corrected.
[0034]
When the rotation of the first document transport means 114 is started under the control of the control means C, the document is read at the image reading position on the first surface, and the second document transport means 115 and the transport path switching member K2 are rotated. Under the regulation of the back side, the document reaches the document reversing means 117.
[0035]
The rotation of the document reversing means is stopped at the timing when the rear end of the document in the transport direction is sandwiched by the document reversing means 117, and the document is reversed by clockwise rotation following the reverse rotation control immediately after. In the same manner as when reading the surface, the document comes into contact with the first document conveying device 114 that is not rotating via the intermediate conveying device 118 and the conveyance path switching member K1, and the skew is corrected.
[0036]
Next, the image reading position is reached by the start of rotation of the first document conveying means 114, and while the image on the second surface is sequentially read, the regulation of the second document conveying means 115 and the abdominal side of the conveyance path switching member K2 is performed. Then, the sheet is finally discharged onto the document discharge table 120 by the discharge means 116.
[0037]
Returning to FIG. 1, the ADF 1 is configured to be foldable. The ADF 1 can be raised to open the platen glass 22 and an image can be formed by directly placing a document on the platen glass 22. .
[0038]
The image reading device 2 is a device for reading an image of a document and obtaining image data. The image reading device 2 integrally includes a lamp 231 for irradiating the document via the slit 21 and a first mirror 232 for reflecting light reflected from the document. A first mirror unit 23, a second mirror unit 24 integrating a second mirror 241 and a third mirror 242 that reflect light from the first mirror 232, and a second mirror unit 24. An image reading means comprising an image forming lens 25 for forming an image of the reflected light on a CCD (described later) as an image pickup device, and a linear CCD 26 for photoelectrically converting the light image formed by the image forming lens 25 Having.
[0039]
The analog signal subjected to photoelectric conversion is subjected to A / D conversion after analog processing, subjected to appropriate image processing, and then stored as image data in a memory in the control unit C.
[0040]
The control means C comprises a CPU, and controls the entire apparatus by multitasking.
In other words, the ON signal of the power switch 102 provided in the main body of the apparatus is detected to control the energization of the heating source of the fixing apparatus, and drive control of the related units according to the program flow for the initialization of the apparatus. I do.
[0041]
Further, after the initialization of the apparatus is completed, the idling state is maintained, and the operation according to the image forming mode selected and instructed is performed via the drive control of each drive unit in accordance with the pressing of the start button 101 for image formation. Let it.
[0042]
In a mode in which the image reading device 2 reads the original sent by the ADF 1, the first mirror unit 23 and the second mirror unit 24 are fixed at the illustrated positions.
[0043]
The reading of the image of the original placed on the platen glass 22 is performed by moving the first mirror unit 23 and the second mirror unit 24 along the platen glass 22 while maintaining the optical path length. Performed by
[0044]
The image forming unit 3 includes a photosensitive drum 31 having a photoconductive photosensitive layer as an image carrier on the surface, a charger 32 including a charging electrode for uniformly charging the surface of the photosensitive drum 31, and an image after image processing. Laser writing means 33, which is operated based on the data and is an exposure means for exposing the photosensitive drum 31 to form an electrostatic latent image, and an electrostatic latent image formed on the photosensitive drum 31 Magnetic brush type developing means (hereinafter referred to as a developing device) 34 having a developing sleeve 300 for forming a toner image by reversal developing the toner image onto a transfer material (hereinafter referred to as paper) made of plain paper or the like. A transfer unit (hereinafter, referred to as a transfer device) 35 including a transfer electrode performs corona discharge from the back surface of the sheet on which the toner image has been transferred, for example, by AC or a voltage in which AC and DC are superimposed on each other. Separating means 36 to facilitate separation of the sheet from the top 31, and a cleaning means 37 such as for cleaning the photosensitive drum 31 after the transfer process is completed.
[0045]
A transport belt 38 transports the separated sheet to the fixing device 9.
The main components of the fixing device 9 include a fixing processing unit including a heating source H, and an upper fixing roller 900 that independently rotates around the fixing source H, and a lower fixing roller 903 that rotates while being pressed against the fixing upper roller 900. . 61 is a fixing discharge roller, 62 is a conveyance path switching member for selectively switching the conveyance path of paper, 63 is a paper discharge roller, and 64 is a paper discharge tray on which paper discharged from the apparatus can be stacked.
[0046]
In the image formation by the above configuration, the photosensitive drum 31 rotating in the direction of the arrow is sequentially charged by the appropriate driving means by the charger 32, and then the electrostatic latent image corresponding to the document image is exposed by dot exposure by the laser writing means 33. An image is formed, and the electrostatic latent image is formed into a toner image by contact development or non-contact development using a developing device 34, and thereafter, from any of the paper feed trays (400, 410, 420) of the paper storage unit 4 The fed sheet P is fed toward the transfer area by the rotation of the registration roller 56 as a second sheet feeding unit, and the toner image is transferred onto the sheet via the operation of the transfer unit 35. It is achieved by transferring.
[0047]
Actually, a process for forming a toner image on the photosensitive drum 31 is performed in a state where the sheet reaches the registration roller 56, in synchronization with the sheet feeding accompanying the start of rotation of the registration roller 56. To start.
[0048]
Therefore, the distance from the writing unit to the transfer unit and the distance from the registration roller to the transfer unit are set to be the same, and the linear speeds of the photosensitive drum 31, the registration roller 56, and the pre-transfer roller 57 are set to be the same. is there.
[0049]
The sheet after the transfer is separated from the photosensitive drum 31 by the action of the separating means 36, and is discharged outside the apparatus after being subjected to the heating / pressing action of the fixing device 9.
[0050]
On the other hand, the photosensitive drum 31 that has passed through the transfer area further continues to rotate, and the residual toner is removed by the cleaning unit 37 to prepare for the next image formation.
[0051]
Returning to the description of the configuration, paper feed trays 400, 410, and 420 for storing the paper P in a stacked state are vertically arranged in the paper storage unit 4 (the paper P is shown only in the paper feed tray 400). Each of the paper feed trays is provided so that a dedicated paper feed roller 401, 411, 421 and a pair of separation rollers 403, 413, 423, which are separation means for preventing stacking, can be integrally pulled out.
[0052]
The paper feed unit 5 includes a pair of transport rollers (hereinafter, also referred to as “transport rollers”) R1 as transport means for transporting the paper P from each of the paper feed trays 400, 410, and 420 to the image forming unit 3. R2, R3, R4, R5, R6 are provided.
[0053]
Reference numeral 55 denotes a conveyance roller provided downstream of the conveyance roller R6 when viewed in the conveyance direction of the paper P, and a conveyance path of the paper sent out through the reverse conveyance section 8 and, for example, a paper fed from the paper feed tray 400. At the junction with the transport path.
[0054]
The reverse discharge / refeed unit 6 is an area for reversely discharging the sheet P after the transfer and fixing, and re-feeding the sheet P in accordance with the duplex image forming mode. The discharged sheet P is directly discharged to the outside of the apparatus, when the sheet P is discharged after being turned upside down, or when the sheet P is directed to the registration roller 56 to form an image on the back surface (second surface) of the sheet P. And a conveyance path switching member (hereinafter, simply referred to as a switching member) 62 for switching the conveyance path when the sheet is fed again.
[0055]
When the paper P on which the image has been formed is to be discharged as it is, that is, with the transfer image surface facing upward, the switching member 62 is held at the position shown by the one-dot chain line in FIG. When the sheet P is conveyed by the fixing and discharging roller 61, the switching member 62 is held at the position shown by a solid line in FIG. And stops the operation of the roller group at the timing when the rear end reaches the position in front of the transport roller 600. Thereafter, the rotation direction of the transport roller 600 is rotated in the opposite direction, whereby the switching is performed. The sheet passes through the left side of the member 62 and is discharged to a discharge tray 64 outside the apparatus via a discharge roller 63.
[0056]
Further, in the case of the double-sided image forming mode in which an image is formed on the second side of the sheet P following the first side, the switching member 62 is held at a position shown by a solid line in FIG. Is fed to the reverse transport section 8 via the transport rollers 600 and 610 of the reverse discharge / re-feed section 6 driven by the discharge motor, and the reverse transport section 8 reverses the sheet P. , Is sent out toward the registration rollers 56.
[0057]
The process during which a transfer image is obtained on the second surface of the sheet P is the same as described above, and the sheet P after the fixing process is discharged according to any of the above-described embodiments.
[0058]
The reversing conveyance unit 8 feeds the paper P conveyed by the conveyance roller 610 further rightward, stops the rotation at the timing of nipping the rear end, and then controls the conveyance roller to rotate in the reverse direction. A pair 800 is provided, and is conveyed along a conveyance path extending rightward after drawing an arc upward from the middle of the conveyance in the left direction due to the reverse rotation of the conveyance roller pair 800.
[0059]
Reference numerals 803, 805, 807, 809, and 811 including the transport roller pair 800 are a plurality of transport roller pairs (hereinafter simply referred to as transport rollers) provided on the transport path of the reverse transport unit 8.
[0060]
Next, a specific configuration of the ADF will be described with reference to FIG. FIG. 2 is an enlarged schematic diagram showing a main part of the ADF according to the present embodiment.
[0061]
It should be noted that description overlapping with the contents described so far will be avoided as much as possible.
In the figure, the same reference numerals are given to the same means (members) as the already-described means (members).
[0062]
In the figure, the first document conveying means 114 is provided on the near side (upstream side) of the image reading position and in the vicinity (near) of the image reading position in the conveying direction of the document.
[0063]
Here, the close position (nearby) means that there is an interval between the first document conveying means 114 and the image reading position where a sensor according to the present invention can be disposed, and the position is close to the image reading position. Means that the document conveying means is not located at a position that is meaninglessly separated.
[0064]
The image reading position refers to a certain area of the transparent glass T provided by using the slit 21, and more specifically, for example, a limitation in which an alternate long and short dash line written on the transparent glass T is set as an optical axis center. Indicates the narrow area.
[0065]
The ADF according to the present embodiment includes a guide member G including a region facing the image reading position and having a length that extends over a predetermined range in the document conveyance direction.
[0066]
In other words, one end of the guide member G extends to the vicinity of the first document conveying means 114, and the other end thereof extends to the vicinity of the second document conveying means 115.
[0067]
Further, an opposing surface GT (on the back side of the original) of the guide member G facing the image reading position has the same horizontal plane as the surface of the transparent glass T, and the original at the image reading position has two opposing surfaces. It is transported in a regulated state.
[0068]
In addition, the roller configuration located inside the pair of rollers constituting the first document conveying means 114 and / or the second document conveying means 115 to which the guide member G is related is attached to a mounting shaft and a gap in the axial direction. The guide member G is provided with a convex portion at one end and / or both ends thereof, which can be inserted between the ring-shaped rollers. By assembling them together, the original can be guided stably over a longer range, and the degree of freedom in the design of this area is wide.
[0069]
S1 and S2 in the figure are reflection optical sensors, and the original first transport means 114 and the image reading position (hereinafter, for convenience of explanation, the transparent glass T is used as the image reading position instead of indicating the reading position). ), And on the same phase in a direction orthogonal to the document conveyance direction, with an interval therebetween.
[0070]
Specifically, the sensors S1 and S2 pass through the center of the width of the document (synonymous with the above-described document passage area extending in the orthogonal direction) in a direction perpendicular to the document transport direction. It is arranged on both sides of the position where it is located.
[0071]
FIG. 3 schematically shows the positional relationship between the rollers located inside and the sensors S1 and S2 among the pair of rollers constituting the first document conveying means 114.
[0072]
The sensors S1 and S2 have a function of detecting the leading edge of the conveyed document. A document leading edge detection signal (output signal) of the sensors S1 and S2 is taken into the control means C, and a bending amount (skew amount) and a bending direction of the document are calculated from a difference between the two detection times.
[0073]
The calculation result includes the bending direction, corrects (rotates) the read image by an amount corresponding to the bending amount, and forms an unbent toner image on the photosensitive drum 31 when forming an image on the photosensitive drum. Is image-processed so that can be formed.
[0074]
In other words, the calculation result is a factor for correcting image data on which the laser writing unit 33 controls exposure.
[0075]
The image forming apparatus according to the present embodiment is configured on the basis of the center. Therefore, the sensors S1 and S2 are provided on the basis of the center, as understood from the above description. . Although this is designed to be compatible with a document having a postcard size (100 mm × 148.2 mm) or more, the present invention is not limited to this numerical value.
[0076]
The reason that the first document conveying means and the sensor contributing to the skew correction of the document are attached to the above-described location is that the leading edge of the document in the double-sided mode is particularly attached to the first document conveying means 114. This is because, even if the conveyance path to reach the paper is long and the registration at the leading edge of the document is not as expected at that time, the degree of inconvenience is reduced as much as possible to increase the control accuracy.
[0077]
In addition, at least one of the sensors S1 and S2, the leading edge detection signal of the original, for example, the first leading edge detection signal of the original is also used as a control signal for determining the start timing of reading by the image reading means.
[0078]
However, in the present embodiment, for example, when the sensor S2 detects the leading edge of the document with a delay of several μsec to several tens of μsec after the sensor S1 detects the leading edge of the document, a case where the sensor S1 detects the leading edge of the document is normal. As a reference (for example, a mode in which reading is started by the image reading means after a predetermined time including a certain time spent for feeding the document from the document leading edge detection signal of the sensor S1 to the image reading position), the output time difference between the two sensors The reading by the image reading means is started after a time obtained by adding half the time (time interval) to the predetermined time.
[0079]
This configuration is substantially the same as detecting the center position of the width of the leading edge of the document.
In FIG. 2, S10 is a document leading edge detection sensor provided near the upstream of document registration means (registration means for a document in the one-sided copy mode), and S20 is a double-sided document provided near the upstream of the document conveyance means. The document leading edge detection sensor in the copy mode detects the registration state of the document, and the detection signal is processed in the flow so as to prompt the next processing operation.
[0080]
The above configuration utilizes the output signal of the sensor S1 or S2 installed in the vicinity of the image reading position, and eliminates the need for a dedicated sensor for controlling the timing of starting reading, thus simplifying the configuration. In addition to this, there is an effect that the accuracy of the reading start can be improved.
[0081]
FIG. 4 is a diagram schematically showing a control flow relating to document bending, and the outline of the steps has been described above, so that it will be complementarily described here.
[0082]
When the document skew detection process is started, the presence / absence of the document leading edge detection signal of the sensors S1 and S2 is obtained from the output signal change (step 1).
[0083]
Next, it is determined whether the first output signal is output from the sensor S1 or the sensor S2. At the same time, the output from the second sensor is based on the time when the first output signal is obtained from the first sensor. The time until the signal is output is counted by the counter (step 2).
[0084]
The bending direction and the amount of bending of the document are calculated from the time difference between the outputs of the two sensors S1 and S2 (step 3).
[0085]
The amount of curving of the document, which is essentially the amount of curving of the image read by the reading means, is subjected to image rotation processing corresponding to the amount of curving (step 4).
[0086]
Image formation is performed based on the corrected data (step 5).
The above-described correction control can be achieved by, for example, one subroutine provided in the control unit C, and the image rotation correction can be performed during image processing.
[0087]
The image reading unit or the image forming unit in the above embodiment does not restrict the present invention, and the configuration of the ADF is not limited to this mode. For example, a configuration may be adopted in which the function of the document registration unit 113 is entrusted to the document conveyance unit 114.
[0088]
【The invention's effect】
Using the document leading edge detection signals from the two sensors provided near the image reading unit, the amount of document bending is detected, and the read image corresponding to the amount of document bending from the sensor is read. It is possible to achieve a plurality of functions such as controlling the rotation and controlling the timing of the start of image reading, thereby achieving a good image formation such as a simple configuration of the apparatus and high accuracy of the image reading timing. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus including a digital copying machine.
FIG. 2 is a schematic diagram showing an enlarged main part of the ADF in the present embodiment.
FIG. 3 is a diagram schematically illustrating a positional relationship between a roller located inside and a sensor among a pair of rollers constituting a document conveying unit;
FIG. 4 is a diagram schematically illustrating a control flow relating to document bending.
[Explanation of symbols]
1 Automatic Document Feeder (ADF)
110 Document placement means (document placement table)
111 Paper feeding means
112 Document separation means
113 Document Registration Means
114 Document Conveying Means (Document First Conveying Means)
115 Document Second Conveying Means
120 Document output tray
S1, S2 sensor
2 Image reading device
3 Image forming unit

Claims (2)

Document placement means, paper supply means for feeding a document placed on the document placement means, transport means for transporting the fed document toward an image reading position, provided at the image reading position Image reading means, and an image forming apparatus having an image forming means,
The transport unit is provided near the front side of the image reading position when viewed in the transport direction of the document,
Two sensors are provided between the conveyance unit and the image reading position and in the same phase in a direction orthogonal to the conveyance direction of the document, and the document is bent based on the leading edge detection signal of the document by the two sensors. Detecting the amount and the bending direction, and controlling the start timing of image reading by the image reading means,
An image forming apparatus comprising: The image read by the image reading means is subjected to image processing and is taken into a memory as image data. The image forming apparatus according to claim 1, wherein the exposure is performed based on an image.

Images