JP5132287B2 - Sheet conveying apparatus, sheet conveying method, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet, a sheet conveying method, and an image forming apparatus.

  In image forming devices such as copiers and laser printers, corrections are made to the skew (skew) of the paper being transported and the shift (lateral registration) of the position (horizontal registration) in the direction perpendicular to the transport direction (paper width direction). A paper aligning device has been proposed.

FIG. 9 is a diagram showing a schematic configuration of a lateral deviation detection / correction unit as a conventional sheet aligning device. The lateral deviation detection / correction unit is provided with a pair of conveyance rollers 1901 for nipping and conveying the paper so as to be movable in the axial direction (the width direction of the paper), and at the lateral deviation reference position in the vicinity of the conveyance roller pair 1901 A paper detection sensor 1800 for detecting the edge of the edge is disposed. The lateral deviation detection / correction unit detects the position of the edge in the width direction of the sheet being conveyed by the sheet detection sensor 1800, and moves the pair of conveyance rollers 1901 in the axial direction while holding the sheet based on the detection result. Move to match the lateral shift (see Patent Document 1). As a result, the lateral shift of the paper can be corrected and the paper can be conveyed at an appropriate conveyance reference position.
Japanese Patent Laid-Open No. 06-298435

  However, in the conventional image forming apparatus described above, there is the following problem in the case where the conveyance roller pair is shifted in the horizontal direction by the detected lateral deviation amount. As the sheet detection sensor, a CIS (contact image sensor) in which a pair of elements each having a light emitting portion and a light receiving portion for reflected light are arranged in an array is often used. The CIS has a configuration in which a plurality of elements are arranged in a direction orthogonal to the paper transport direction, and a boundary line (n pixels in FIG. 10A) between the reception of reflected light from the paper and the reception of light from the outside is used for the paper. Detect as end. FIG. 10 is a diagram illustrating detection of the sheet edge.

  Here, when dust such as paper dust adheres to the light emitting unit or the light receiving unit, the edge of the paper may be erroneously detected due to the dust. FIG. 4B shows a case where dust adheres to a position corresponding to the seventh to ninth pixels of the CIS. If there is a difference between the amount of light reflected by dust and the amount of light reflected by the paper, it will lead to erroneous detection of the edge of the paper. In order to prevent this, in FIG. 6C, detection is performed in advance with no paper in the CIS, and 7 to 9 pixels having different detection levels are regarded as defective detection pixels. When detecting the edge of the paper, as shown in FIG. 6D, the output from the 7 to 9 pixels regarded as defective pixels is not used, but masked by the output of the peripheral pixels (the previous pixel level = paper in the figure). Thus, there is a method for accurately detecting n pixels at the end of the paper.

  FIG. 11 is a diagram showing a specific example of dust detection. Even if the dust detection portion is masked, if dust is in the vicinity of the paper edge position to be detected, for example, in the (n) to (n + 2) pixels, as described above, (n) to (n + 2). ) Pixels are masked at the mask level of the surrounding pixels (with paper). As a result, the end of the sheet is erroneously detected as (n + 2) pixels. Although not shown in the drawing, even if the mask level is set to no paper, the detection error will not change. As described above, the detection of the edge of the paper by the CIS has a problem that erroneous detection occurs due to dust adhesion or element failure.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus, a sheet conveying method, and an image forming apparatus that can accurately detect the position of an end portion of a sheet even if a partial abnormality occurs in a plurality of reading units. And

In order to achieve the above-mentioned object, the position of the sheet end portion in the orthogonal direction has conveying means for conveying the sheet and a plurality of reading sections provided along a direction orthogonal to the conveying direction of the sheet. A sheet position detecting means for detecting a shift amount, a shift amount calculating means for calculating a shift amount based on the position of the edge of the sheet detected by the sheet position detecting means, and moving the conveyed sheet in the orthogonal direction a moving means for Ru is, before the position of the end portion of the sheet is detected by the sheet position detection means, among the plurality of reading portions, and detecting means for detecting a position of the reading portion having the abnormality, to the orthogonal And determining whether or not a reference position that is a target of the position of the end portion of the sheet in the direction is within a predetermined range including the position of the abnormal reading unit detected by the detection unit. And means, the result of the determination, if the reference position is within the predetermined range, the moving means, said when the position of the end of the sheet is assumed to be coincident with the reference position as the position of the end portion of the sheet deviates from the predetermined range, before the position of the end of the sheet by the sheet position detection means is detected, moves the sheet to be pre-Symbol transported in the direction the perpendicular The shift amount calculation unit is configured so that the position of the end portion of the sheet deviates from the predetermined range when the position of the end portion of the sheet is assumed to match the reference position by the moving unit. After the conveyed sheet has moved in the orthogonal direction, the difference between the position of the end of the sheet detected by the sheet position detecting unit and the reference position is calculated as a shift amount, and the moving unit Further, only the shift amount of the calculated, characterized in that moving the sheet to be the transport.

  In the sheet conveying apparatus according to the first aspect of the present invention, it is detected in advance whether the reading unit at a position likely to be used for detecting the position of the end portion of the sheet is abnormal, and in the case of abnormality, detection at this position is avoided. Before the sheet position is detected, the sheet is moved in the direction orthogonal to the conveying direction in advance. Therefore, it is possible to accurately detect the position of the end portion of the sheet even if a partial abnormality occurs in the plurality of reading units.

According to the sheet conveying apparatus of the second aspect, it is possible to cope with various sheet sizes . According to the sheet transporting device according to 請 Motomeko 4, it can easily detect the position of the reading portion having the abnormality. According to the sheet conveying apparatus of the fifth aspect, it is possible to cope with the amount of the sheet position that can be changed and the detection accuracy.

  Embodiments of a sheet conveying apparatus, a sheet conveying method, and an image forming apparatus according to the present invention will be described with reference to the drawings. The sheet conveying apparatus of this embodiment is mounted on an electrophotographic color copying machine that is a color tandem type image forming apparatus.

  FIG. 1 is a cross-sectional view showing the overall configuration of an electrophotographic color copying machine according to an embodiment. The electrophotographic color copying machine is a color image output apparatus in which a plurality of image forming units are arranged in parallel and adopts an intermediate transfer method. The electrophotographic color copying machine 1 includes an image reading unit 2 and an image output unit 3.

  The image reading unit 2 optically reads a document image and converts it into an electrical signal, and transmits the electrical signal to the image output unit 3. The image output unit 3 includes a plurality (four in this embodiment) of image forming units 10a, 10b, 10c, and 10d, a paper feeding unit 20, an intermediate transfer unit 30, a fixing unit 40, cleaning units 50 and 70, A photo sensor 60, a control unit 80, and the like are included.

  Each unit will be described in detail. Since the image forming units 10a, 10b, 10c, and 10d have the same configuration, they are collectively referred to as the image forming unit 10. In each of the image forming units 10 (10a, 10b, 10c, and 10d), a drum-shaped electrophotographic photosensitive member as a first image carrier, that is, the photosensitive drums 11a, 11b, 11c, and 11d are rotatably shafts. It is supported and rotated in the direction of the arrow in the figure. Each photoconductor drum 11a, 11b, 11c, 11d has the same configuration.

  A primary charger 12a, an optical system 13a, a folding mirror 16a, a developing unit 14a, and a cleaning device 15a are arranged in the rotational direction opposite to the outer peripheral surface of the photosensitive drum 11a. Similarly, a primary charger 12b, an optical system 13b, a folding mirror 16b, a developing unit 14b, and a cleaning device 15b are arranged in the rotation direction so as to face the outer peripheral surface of the photosensitive drum 11b. Similarly, a primary charger 12c, an optical system 13c, a folding mirror 16c, a developing unit 14c, and a cleaning device 15c are arranged in the rotational direction so as to face the outer peripheral surface of the photosensitive drum 11c. Similarly, a primary charger 12d, an optical system 13d, a folding mirror 16d, a developing unit 14d, and a cleaning device 15d are arranged in the rotational direction so as to face the outer peripheral surface of the photosensitive drum 11d.

  The primary chargers 12a to 12d give a uniform charge amount to the surfaces of the photosensitive drums 11a to 11d, respectively. The optical systems 13a to 13d respectively expose the photosensitive drums 11a to 11d via the folding mirrors 16a to 16d using light beams (for example, laser beams) modulated according to the recording image signal from the image reading unit 2. Thereby, electrostatic latent images are formed on the photosensitive drums 11a to 11d.

  The development units 14a to 14d for the respective colors respectively store four color developers (toners) such as yellow, cyan, magenta, and black. Each of the developing units 14a to 14d has a developing sleeve for visualizing the electrostatic latent images formed on the photosensitive drums 11a to 11d, and a coating roller for uniformly feeding the toner to the sleeve. Each visualized visible image (toner image) is a belt-like intermediate transfer member as a second image carrier that constitutes the intermediate transfer unit 30 with the image transfer regions Ta, Tb, Tc, and Td, that is, Transferred to the intermediate transfer belt 31.

  On the downstream side of the image transfer areas Ta, Tb, Tc, and Td, the cleaning devices 15a, 15b, 15c, and 15d scrape the toner remaining on the photosensitive drums 11a to 11d without being transferred to the intermediate transfer belt 31, respectively. Drop and clean the drum surface. By the above process, image formation with each toner is sequentially performed.

  The paper feed unit 20 includes a cassette 21 for storing the transfer material P and a manual feed tray (not shown). Note that the transfer material may be referred to as a sheet, a sheet, or a recording medium. The paper feed unit 20 includes a pickup roller 22 for feeding the transfer material P one by one from the cassette 21 or the manual feed tray, and a pair of paper feed rollers 23-1, 23-2 for further transporting the fed transfer material P. , 23-3, and a paper feed guide 24. The paper feed unit 20 also includes a lateral deviation detection / correction unit 100 that detects and corrects lateral deviation of the fed paper. Further, the paper feeding unit 20 has a registration roller 25 for feeding the transfer material P to the secondary transfer region Te.

  Next, the intermediate transfer unit 30 will be described in detail. The intermediate transfer belt 31 is wound while being stretched between the driving roller 32, the driven roller 33, and the secondary transfer counter roller 34. The driving roller 32 transmits driving force to the intermediate transfer belt 31. The driven roller 33 is driven by the rotation of the intermediate transfer belt 31 as a tension roller that applies an appropriate tension to the intermediate transfer belt 31 by a biasing force of a spring (not shown). A primary transfer plane A is formed between the driving roller 32 and the driven roller 33. The driving roller 32 is driven by a pulse motor (not shown).

  In the primary transfer regions Ta to Td where the respective photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other, primary transfer chargers 35 a to 35 d are disposed on the back of the intermediate transfer belt 31. Each of the primary transfer chargers 35a to 35d has the same configuration.

  Further, a secondary transfer roller 36 is disposed to face the secondary transfer counter roller 34 around which the intermediate transfer belt 31 is wound, and a secondary transfer region Te is formed by a nip with the intermediate transfer belt 31. ing. The secondary transfer roller 36 is pressed against the intermediate transfer belt 31 with an appropriate pressure. The paper whose lateral deviation has been corrected by the lateral deviation detection / correction unit 100 is conveyed to the secondary transfer roller 36 by the registration roller 25 so that the timing at which the toner image on the intermediate transfer belt 31 reaches the secondary transfer roller 36 coincides. Is done. Then, the toner image on the intermediate transfer belt 31 is transferred onto the paper by the secondary transfer roller 36.

  A cleaning unit 50 for cleaning the image forming surface of the intermediate transfer belt 31 is disposed downstream of the secondary transfer region Te of the intermediate transfer belt 31. The cleaning unit 50 includes a cleaning blade 51 for removing toner on the intermediate transfer belt 31 and a waste toner box 52 for storing waste toner.

  The driving roller 32 of the intermediate transfer belt 31 is provided with a cleaning blade 70 and a pulse motor (not shown) for attaching / detaching the cleaning blade 70 to / from the intermediate transfer belt 31. The cleaning blade 70 is also for removing toner on the intermediate transfer belt 31.

  The fixing unit 40 includes a fixing roller 41a provided with a heat source such as a halogen heater inside, and a fixing roller 41b pressurized by the fixing roller 41a (the fixing roller may also include a heat source). The fixing unit 40 includes a guide 43 for guiding the transfer material P to the nip portion of the roller pair 41 including the fixing roller 41a and the fixing roller 41b, and a fixing heat insulating cover 47 for confining heat of the fixing unit 40 inside. Have. Further, an inner discharge roller 44 for guiding the transfer material P discharged from the roller pair 41 to the outside of the apparatus, an outer discharge roller 45, and a discharge tray 48 on which the transfer material P is stacked are provided.

  When a toner image is also formed on the back surface of the paper, the paper P that has passed through the fixing unit 40 is conveyed in the direction of the reverse path 201. The sheet P is reversed in the reverse path 201, passes through the double-sided path 202, and reaches the refeed unit 203. Then, after the paper P is temporarily stopped by the paper re-feed unit 203, the conveyance is resumed at a predetermined timing, and the paper P joins the path of the paper feed rollers 23-2 and 23-3 and is conveyed to the lateral deviation detection / correction unit 100. Similarly, the lateral shift is corrected.

  In the present embodiment, only one paper feed stage is shown, but a plurality of paper feed stages can be provided in the vertical direction to feed paper from each paper feed stage.

  FIG. 2 is a diagram showing a schematic configuration of the lateral deviation detection / correction unit 100. In the drawing, the sheet is conveyed according to the sheet conveyance direction Y from right to left. The lateral deviation detection / correction unit 100 includes a lateral deviation detection CIS 800, a CIS detection timing reference sensor 900, a lateral deviation correction roller 902, and a correction timing reference sensor 901. The lateral deviation detection CIS 800 arranges a plurality of elements (pixels) in the X direction orthogonal to the paper transport direction, and detects the edge of the paper from the boundary line between the reflected light from the paper and the light received by diplomacy. The lateral displacement detection CIS 800 corresponds to a sheet position detection unit. The CIS detection timing reference sensor 900 detects the arrival of the leading edge of the paper serving as a reference for determining the detection timing. The lateral deviation correction roller 902 corrects the end position by shifting the paper in the X direction by moving in the X direction while holding the paper. The correction timing reference sensor 901 detects the arrival of the leading edge of the paper as a reference for determining the shift correction timing.

  FIG. 3 is a diagram illustrating a configuration of the lateral deviation detection / correction control unit 200. The lateral deviation detection / correction control unit 200 controls the lateral deviation detection / correction unit 100 and is provided in the control unit 80. The lateral deviation detection / correction control unit 200 includes a timing sequencer (TS1) 210, a correction roller control unit (RC1) 220, a position comparison unit (CMP1) 230, a CIS control unit (CC1) 240, a storage unit (MEM1) 250, and a storage unit. (MEM2) 260.

  The timing sequencer (TS1) 210 determines the operation timing of each unit based on the inputs of the CIS detection timing reference sensor 900 and the correction timing reference sensor 901. The correction roller control unit (RC1) 220 controls the motor M1 that drives the lateral deviation correction roller 902 in accordance with the direction and movement amount instructions from the position comparison unit 230. The position comparison unit (CMP1) 230 performs comparison processing using a reference position X1, an abnormal position X2, and a range specification value REG, which will be described later, and functions as a determination unit. The CIS control unit (CC1) 240 controls the lateral deviation detection CIS 800. The storage unit (MEM1) 250 stores an LUT (Look Up Table) indicating the correspondence between the paper size and the reference position X1. The storage unit (MEM2) 260 stores an LUT indicating the correspondence between each pixel and the comparison result. Further, a user interface (UI) 300 such as an operation panel is connected to the lateral deviation detection / correction control unit 200.

  FIG. 4 is a flowchart showing a lateral deviation detection / correction processing procedure executed by the lateral deviation detection / correction control unit (hereinafter referred to as a control unit) 200. First, the control unit 200 inputs print job settings (here, paper size settings) set by the user via the user IF (UI) 300 (step S1). Then, the control unit 200 starts (starts) the print job (step S2).

  The control unit 200 notifies the storage unit (MEM1) 250 of the size set in the UI 300 (step S3). As described above, the storage unit (MEM1) 250 stores an LUT (Look Up Table) indicating the correspondence between the paper size and the reference position X1. Here, the reference position X1 is set to a target paper end position in a direction orthogonal to the paper transport direction, and is a position that differs depending on the paper size. Further, the reference position X1 may be set at any end position on the near side and the far side of the conveyed sheet. The paper size may be set from the UI 300 or may be detected by the paper feeding unit 20 by a known method.

  The control unit 200 reads (acquires) the reference position X1 corresponding to the specified size from the storage unit (MEM1) 250, and sets the reference position X1 in the position comparison unit (CMP1) 230 (step S4). For example, “X1_a4” (actually the pixel number of the lateral shift detection CIS 800) corresponding to the “A4” size is read out.

  When the operation of the lateral deviation detection CIS 800 is controlled by the CIS control unit (CC1) 240, the control unit 200 performs detection (pre-detection) by the lateral deviation detection CIS 800 in the absence of a sheet in response to an ON command from the timing sequencer (TS1) 210. This is performed (step S5). The control unit 200 uses the CIS control unit (CC1) 240 to compare the detected output level (pixel reading value) with a preset sheet presence / absence threshold value Vd for each pixel (step S6).

  When the detection output level (pixel reading value) in each pixel of the CIS 800 is larger than the paper presence / absence threshold value Vd, the control unit 200 regards this pixel as abnormal due to dust adhesion and the like, and stores this pixel as the abnormal position X2 in the storage unit (MEM2) 260. (Step S7). The storage unit (MEM2) 260 stores data indicating normal / abnormal results in each pixel. The contents of the storage unit (MEM2) 260 are notified to the position comparison unit (CMP1) 230 as the abnormal position X2. On the other hand, when the pixel read value is equal to or smaller than the sheet presence / absence threshold value Vd in step S6, the control unit 200 proceeds to the process of step S8 as it is.

  In the position comparison unit (CMP1) 230, the control unit 200 uses the paper reference position X1, the abnormal position X2 of the lateral deviation detection CIS 800, and the range designation value REG set in advance, and performs the determination shown in Formula (1) ( Step S8). That is, it is determined whether or not the reference position X1 is within a predetermined range determined from the abnormal position X2 and the range designation value REG.

X2-REG <X1 <X2 + REG (1)
Here, the range specification value REG is related to the amount of paper position that can vary from the pre-detection in the absence of paper to the lateral deviation detection and the detection accuracy of the lateral deviation detection CIS 800, and is determined in advance via the UI 300 or the like. . FIG. 5 is a diagram showing a predetermined range including the abnormal position X2 compared with the reference position X1. As a predetermined range to be compared with the reference position X1, range designation values REG are set on both sides centered on the abnormal position X2.

  When the relationship of Formula (1) is established, the control unit 200 calculates the shift direction and the amount of movement of the sheet for detecting the edge position in order to avoid the abnormal pixel X2 (step S9). This shift for edge detection is called pre-shift. Here, the pre-shift direction may be uniformly the same direction, or may be changed according to the size. Further, the movement amount may be uniformly set to the same movement amount (for example, REG), or the above-described equation (1) may be continuously determined and moved until it deviates from this conditional equation.

  The control unit 200 performs pre-shifting according to the direction and movement amount calculated in step S9 (step S10), and reliably avoids the use of abnormal pixels in the lateral shift detection CIS 800. On the other hand, when the relationship of Formula (1) is not established in step S8, the control unit 200 proceeds to the process of step S11 as it is.

  Thereafter, the control unit 200 detects the edge of the sheet by the lateral deviation detection CIS 800, and sets the lateral deviation detection value X3 (step S11). Then, the control unit 200 calculates a lateral shift amount (also simply referred to as a shift amount) (step S12). Here, the shift amount is a difference | X3−X1 | between the lateral deviation detection value X3 and the reference position X1 corresponding to the paper size. That is, the control unit 200 also functions as a shift amount calculation unit.

  The control unit 200 performs the horizontal shift of the correction roller 902 so as to return the shift amount as described above (step S13), and after the trailing edge of the sheet has come out of the correction roller 902, the correction roller 902 is returned to the home position (HP) ( Step S14).

  Thereafter, the control unit 200 determines whether or not the print job has ended (step S15). If the print job has not ended, the control unit 200 returns to the process of step S3, and performs the above processing for the next page until the print job ends. repeat. On the other hand, when the print job is finished, the control unit 200 finishes this process.

  FIG. 6 is a diagram showing the positional relationship between the paper and the lateral deviation detection CIS 800. Numerical values (1, 2, 3,..., (N−2), (n−1), n, (n + 1),...) Written on the lateral shift detection CIS 800 each represent a pixel number, that is, a pixel position. ing. FIG. 6A shows a state before the pre-shift of the paper. In the state before the pre-shift, the positional relationship between the paper whose reference position is n and the lateral displacement detection CIS 800 is shown, and dust is attached to the positions n, (n + 1), and (n + 2) of the lateral displacement detection CIS 800. The pre-detection indicates that these pixels are masked at the level of the adjacent pixel (n−1) (= paper level).

  As described above, when the reference position X1 = n, the abnormal position X2 = n to (n + 2), and REG = 4, Expression (1) becomes Expression (2).

(X2-REG = n-4) <(X1 = n) <(X2 + REG = n + 6) (2)
That is, since the relationship of the mathematical formula (1) is established, the pre-shift operation is performed because there is a high possibility that the sheet will arrive near the abnormal portion of the lateral deviation detection CIS 800.

  FIG. 5B shows a lateral shift detection result by the lateral shift detection CIS 800 after the paper is pre-shifted to the position (n + 8). The lateral deviation detection position (n + 8) is correctly detected with respect to the paper position (n + 8) after pre-shifting is performed while avoiding use of the abnormal portions n to (n + 2) of the lateral deviation detection CIS 800.

  FIG. 7 is a timing chart of the lateral deviation detection / correction operation. FIG. 8 is a diagram showing a positional relationship among the paper, the CIS detection timing reference sensor 900, and the correction roller 902 when performing the lateral deviation detection / correction operation.

  First, the control unit 200 performs pre-detection by the CIS 800 in the absence of paper after the time T1 when the paper reaches the lateral displacement detection CIS 800 with reference to the timing when the leading edge of the paper passes through the CIS detection timing reference sensor 900 (see FIG. 8 (a)).

  Next, the controller 200 pre-shifts the sheet at time T2 (> T1) when the leading edge of the sheet reaches the lateral deviation correction roller 902 (becomes in a state of being engaged with the correction roller 902) (see FIG. 8B). As described above, pre-shifting is not performed depending on the detection result.

  Then, the control unit 200 performs lateral shift detection at time T3 (> T2) after the preshift operation is finished (see FIG. 8C).

  Thereafter, the control unit 200 performs lateral shift correction at time T4 (> T3) with reference to the timing when the leading edge of the sheet reaches the correction timing reference sensor 901 (see FIG. 8D).

  At time T5 (> T4) after the completion of the lateral shift correction, the control unit 200 returns the correction roller 902 to the home position (HP) (see FIG. 8E), and the series of operations ends. If there is a next page in the print job, the process is repeated in the same manner from the arrival of the paper at the CIS detection timing reference sensor 900 again.

  The pre-detection timing T1 for detecting whether or not there is an abnormal pixel in the lateral deviation detection CIS 800 is set to a predetermined timing after the sensor 900 detects the leading edge of the paper. However, the timing may be any time before the sheet reaches the lateral deviation detection CIS 800, and another timing sensor may be used as a reference. For example, the timing may be a standby mode in which the image forming apparatus waits for an image formation instruction. Similarly, the sensors serving as references for other timings T2 to T5 are not limited to the sensors 900 and 901 described above.

  According to the image forming apparatus of the present embodiment, it is detected in advance whether or not the CIS element (pixel) at the position used for detecting the edge of the sheet is abnormal, and if it is abnormal, the edge detection is performed so as to avoid detection at this position. Pre-shift before. Accordingly, even when a CIS partial abnormality occurs, accurate sheet edge detection is possible. In addition, since the position where the abnormality should be compared is changed according to the paper size, each paper size can be handled. Thereby, highly accurate lateral deviation correction control can be performed. Further, it is possible to easily detect the pixel position of the CIS that cannot be read.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable.

  For example, in the above embodiment, the case where the present invention is applied to the engine conveyance unit in the copying machine has been described. However, the output paper sorts the output product on the front side or the back side of the job for each JOB or number of copies by the optional paper discharge device. The present invention may be applied to a division (shift sort) mechanism or the like.

  Further, the detection of the paper position may be performed on either the front side or the back side of the conveyed paper. Further, the sheet to be conveyed is not particularly limited, such as an OHP sheet and a cardboard sheet in addition to a normal sheet made of a paper medium.

  Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. In addition to the original printing apparatus, the image forming apparatus may of course be a facsimile machine having a printing function, a multifunction machine (MFP) having a printing function, a copying function, a scanner function, or the like.

  In the above-described embodiment, an intermediate transfer member is used as the image forming apparatus, and toner images of each color are sequentially transferred onto the intermediate transfer member, and the toner images carried on the intermediate transfer member are collectively transferred to a recording medium. An image forming apparatus to be transferred is illustrated. However, the present invention is not limited to this transfer method, and an image forming apparatus that uses a recording medium carrier and sequentially superimposes and transfers the toner images of each color onto the recording medium carried on the recording medium carrier. Good.

  In addition, the shapes of the component parts described in the above embodiment, the relative arrangement thereof, and the like should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention is described above. It is not limited only to what is illustrated.

  In the above-described embodiment, the case where the printing method of the composite apparatus is an electrophotographic method has been described as an example. However, the present invention is not limited to the electrophotographic method, and an inkjet method, a thermal transfer method, and a thermal method. It can be applied to various printing methods such as electrostatic method and electric discharge destruction method.

1 is a cross-sectional view illustrating an overall configuration of an electrophotographic color copying machine according to an embodiment. 2 is a diagram illustrating a schematic configuration of a lateral deviation detection / correction unit 100. FIG. 3 is a diagram illustrating a configuration of a lateral deviation detection / correction control unit 200. FIG. 5 is a flowchart showing a lateral deviation detection / correction processing procedure executed by a lateral deviation detection / correction control unit 200. It is a figure which shows the predetermined range containing the abnormal position X2 compared with the reference position X1. 6 is a diagram illustrating a positional relationship between a sheet and a lateral deviation detection CIS 800. FIG. It is a timing chart of a lateral shift detection / correction operation. FIG. 5 is a diagram illustrating a positional relationship among a sheet, a CIS detection timing reference sensor 900, and a correction roller 902 when performing lateral deviation detection / correction operation. It is a figure which shows schematic structure of the lateral deviation detection and correction | amendment part as the conventional paper aligning apparatus. FIG. 6 is a diagram illustrating detection of a paper edge. It is a figure which shows the specific example of dust detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 100 Side shift detection / correction part 200 Side shift detection / correction control part 230 Position comparison part 800 Side shift detection CIS
900 CIS detection timing reference sensor 901 Correction timing reference sensor 902 Side shift correction roller

Claims (8)

Conveying means for conveying the sheet;
A sheet position detecting unit having a plurality of reading units provided along a direction orthogonal to the sheet conveying direction, and detecting a position of an end of the sheet in the orthogonal direction;
Shift amount calculating means for calculating a shift amount based on the position of the edge of the sheet detected by the sheet position detecting means;
Moving means Before moving the sheet to be the transport in the direction the perpendicular,
Detecting means for detecting the position of an abnormal reading section among the plurality of reading sections before the position of the end of the sheet is detected by the sheet position detecting section ;
A determination unit that determines whether or not a reference position that is a target of the position of the end portion of the sheet in the orthogonal direction is within a predetermined range including the position of the abnormal reading unit detected by the detection unit; With
As a result of the determination, when the reference position is within the predetermined range, the moving means determines the position of the end of the sheet when it is assumed that the position of the end of the sheet matches the reference position. position so deviates from the predetermined range, before the position of the end of the sheet by the sheet position detection means is detected, moves the sheet to be pre-Symbol transported in the direction the perpendicular,
The shift amount calculation unit is configured so that the position of the end portion of the sheet deviates from the predetermined range when the moving unit assumes that the position of the end portion of the sheet matches the reference position. After the conveyed sheet moves in the orthogonal direction, the difference between the position of the end portion of the sheet detected by the sheet position detection unit and the reference position is calculated as a shift amount,
The moving means further moves the conveyed sheet by the calculated shift amount .   The sheet conveying apparatus according to claim 1, further comprising an acquisition unit configured to acquire a reference position corresponding to the size of the sheet. 3. The sheet conveying apparatus according to claim 1 , further comprising an image forming unit that forms an image on the sheet after the sheet is moved by the moving unit by the calculated shift amount .   The detection means detects reading values by the plurality of reading units in a state where the sheet is not conveyed, and compares the detected reading values with a threshold value, thereby detecting the abnormal reading unit. The sheet conveying apparatus according to claim 1, wherein the position is detected.   The sheet conveying apparatus according to claim 1, wherein the determination unit determines whether or not a reference position of the sheet is within a predetermined range centered on a position of the abnormal reading unit.   The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is mounted on an image forming apparatus and conveys a sheet used for image formation. A conveying unit that conveys the sheet, and a sheet position detecting unit that includes a plurality of reading units provided along a direction orthogonal to the conveying direction of the sheet, and detects a position of the end of the sheet in the orthogonal direction. the sheet to be the transfer a sheet conveyance method of the sheet conveying device provided with a moving means Before moving in the direction the perpendicular,
A detection step in which the sheet conveying device detects a position of an abnormal reading unit among the plurality of reading units before the position of the end portion of the sheet is detected by the sheet position detection unit ;
Whether the sheet conveying apparatus has a reference position that is a target of the position of the end of the sheet in the orthogonal direction within a predetermined range including the position of the abnormal reading unit detected in the detection step. A determination step for determining
As a result of the determination, when the reference position is within the predetermined range, the position of the edge of the sheet when the position of the edge of the sheet is assumed to match the reference position is the predetermined position. as outside the scope, before the position of the end portion of the sheet is detected by the sheet position detection means, a first moving step of moving the sheet to be pre-Symbol transported in the direction of the perpendicular by the moving means ,
A shift amount calculating step of calculating, as a shift amount, a difference between the position of the end portion of the sheet detected by the sheet position detecting unit and the reference position after the movement in the first moving step;
A second moving step for moving the sheet conveyed by the moving means by the shift amount calculated in the shift amount calculating step;
Sheet conveying method characterized by having a. An image forming apparatus for forming an image on a sheet,
Conveying means for conveying the sheet;
A sheet position detecting unit having a plurality of reading units provided along a direction orthogonal to the sheet conveying direction, and detecting a position of an end of the sheet in the orthogonal direction;
Shift amount calculating means for calculating a shift amount based on the position of the edge of the sheet detected by the sheet position detecting means;
Moving means Before moving the sheet to be the transport in the direction the perpendicular,
Detecting means for detecting the position of an abnormal reading section among the plurality of reading sections before the position of the end of the sheet is detected by the sheet position detecting section ;
A determination unit that determines whether or not a reference position that is a target of the position of the end portion of the sheet in the orthogonal direction is within a predetermined range including the position of the abnormal reading unit detected by the detection unit; With
As a result of the determination, when the reference position is within the predetermined range, the moving means determines the position of the end of the sheet when it is assumed that the position of the end of the sheet matches the reference position. position so deviates from the predetermined range, before the position of the edge portion of the sheet by the sheet position detection means is detected, moves the sheet to be pre-Symbol conveyed in the direction the perpendicular,
The shift amount calculation unit is configured so that the position of the end portion of the sheet deviates from the predetermined range when the moving unit assumes that the position of the end portion of the sheet matches the reference position. After the conveyed sheet moves in the orthogonal direction, the difference between the position of the end portion of the sheet detected by the sheet position detection unit and the reference position is calculated as a shift amount,
The image forming apparatus , wherein the moving unit further moves the conveyed sheet by the calculated shift amount .

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