JP2008254856A - Sheet conveying device, image forming device, and image reading device - Google Patents

Sheet conveying device, image forming device, and image reading device Download PDF

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Publication number
JP2008254856A
JP2008254856A JP2007097888A JP2007097888A JP2008254856A JP 2008254856 A JP2008254856 A JP 2008254856A JP 2007097888 A JP2007097888 A JP 2007097888A JP 2007097888 A JP2007097888 A JP 2007097888A JP 2008254856 A JP2008254856 A JP 2008254856A
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Prior art keywords
sheet
skew
skew correction
correction
roller
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JP2007097888A
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Japanese (ja)
Inventor
Hakuji Inoue
Daisuke Kawaguchi
博慈 井上
大輔 川口
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Canon Inc
キヤノン株式会社
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Priority to JP2007097888A priority Critical patent/JP2008254856A/en
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Abstract

A sheet conveying apparatus, an image forming apparatus, and an image reading apparatus capable of correcting sheet skew with high accuracy are provided.
SOLUTION: First skew detection units 27a and 27b that detect sheet skew upstream of the skew correction rollers 21 and 22 detect sheet skew downstream of the skew correction rollers 21 and 22, respectively. Second skew detection units 28a and 28b are provided. After the first skew correction is performed by the skew correction rollers 21 and 22 on the sheet based on the detection information of the first skew detection units 27a and 27b, and after passing through the skew correction rollers 21 and 22. The second skew correction is performed by the skew correction rollers 21 and 22 based on the detection information of the second skew detection units 28a and 28b.
[Selection] Figure 4

Description

  The present invention relates to a sheet conveying apparatus, an image forming apparatus, and an image reading apparatus, and more particularly to a configuration for correcting skew feeding of a sheet such as a recording sheet or a document conveyed to an image forming unit or an image reading unit.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines, printers, facsimiles, and image reading apparatuses are provided with a sheet conveying device that conveys a sheet such as a recording sheet or a document to the image forming unit or the image reading unit. Some sheet conveying apparatuses include a skew correction unit for correcting the skew of the sheet in order to adjust the posture and position of the sheet before the sheet is conveyed to the image forming unit or the image reading unit. .

  By the way, in recent years, image forming apparatuses have various types of sheets such as coated paper and embossed paper in addition to plain paper, from thin paper to thick paper, or from a small size of postcard to a large size of about 330 mm × 488 mm. An image can be formed.

  Further, in recent years, there has been an increasing demand for higher productivity and smaller size in image forming apparatuses. In order to meet the demand for higher productivity, it is effective to make the gap between the conveyed sheets as small as possible.

  However, when the gap between the sheets is reduced as described above, it is necessary to correct the skew and misalignment of the sheet that occurs when the sheet is fed in a short time. For this reason, there has been proposed a skew correction unit using a so-called active registration skew correction method that corrects skew generated when a sheet is fed while conveying the sheet (patent). Reference 1).

  Here, in this active registration method, for example, as shown in FIG. 17, two sensors 1101a and 1101b are arranged in the width direction which is a direction orthogonal to the sheet conveying direction indicated by an arrow. The skew amount of the sheet S is detected based on a detection signal when the leading edge of the conveyed sheet S passes the sensors 1101a and 1101b.

  Thereafter, the skew correction roller pairs 1103a and 1103b arranged coaxially with a predetermined interval in the width direction are independently driven and controlled by the motors 1102a and 1102b, so that the detected skew amount is obtained. Accordingly, the skew of the sheet S is corrected. This makes it possible to correct skew feeding in a short time even when the sheet interval is small.

As shown in FIG. 18, the sheet conveyance speed at the time of correction of the skew correction roller pair 1103a, 1103b is V L , V R , the thrust pitch between the skew correction roller pair is L RP , and the sheet S is rotated at the turning center O. When the turning speed (angular speed) is ω, the turning speed ω is expressed by the following equation.

Further, as shown in FIG. 19, assuming that the turning radius R ROT from the turning center O of the sheet S to the middle point O ′ between the pair of skew feeding correction rollers 1103a and 1103b, R ROT is expressed by the following equation. .

R ROT · ω≡ (V L + V R ) / 2
From this equation, R ROT is represented by the following equation.

Further, at the time of skew correction, if the force applied to the pair of skew correction rollers 1103a and 1103b is F L and F R , and the conveyance load (back tension) applied to the sheet S is F BT , F L , F R and F BT The relationship of force balance is expressed by the following formula.

F L + F R + F BT ≡0

By this relationship, the relationship of F L, F R, F BT can be expressed by the following equation.

F Lx + F Rx + F BTx = 0
F Ly + F Ry + F BTy = 0

Furthermore, when the distance from the turning center O of the sheet S to the skew correction roller pair 1103a, 1103b is R L , R R , and the conveyance load point applied to the sheet S is R BT (X, Y), the moment balance The relationship is expressed by the following formula.

From R L · F L + R R · F R + R BT · F BT ≡0,
- (R ROT -L RP / 2 ) F Lx - (R ROT + L RP / 2) F Rx + (XF BTy -YF BTx)
= 0

The conveying load F BT according to the sheet S, than R BT ⊥F BT for ideally take revolving conveyor direction and opposite direction of the sheet S,
XF BTx + YF BTy = 0
Therefore,
F Lx = −1 / 2 · {1-2 / L RP · [(X 2 + Y 2 ) / YR ROT ]} · F BTx (1)
F Rx = −1 / 2 · {1 + 2 / L RP · [(X 2 + Y 2 ) / Y−R ROT ]} · F BTx (2)
It becomes.

In general, assuming that the ideal maximum conveyance force F 0 of the skew correction roller pair 1103a and 1103b and the conveyance load applied to the sheet S is F BT , the roller slip rate is experimentally a function of F BT / F 0 . I know that I can express.

Further, assuming that the ideal speed is V 0 and the slip ratio function is f (F BT / F), the conveyance speed V during skew correction is expressed by the following equation.

V = (1−f (F BT / F 0 )) V 0

  Further, assuming that the control time is τ and the slip amount is Δd, the slip amount Δd is expressed by the following equation.

Δd≈ (V 0 −V) τ = f (F BT / F 0 ) V 0 τ

  Here, when the slip amount Δd of the roller is sufficiently small, it is known from experience that the slip ratio function can be approximated to a proportional expression. Therefore, assuming that the constant k, the slip amount Δd is expressed by the following equation.

Δd≈k (F BT / F max ) V 0 τ

The skew correction accuracy is greatly influenced by the difference | Δd Lx −Δd Rx | of the slip amount of the skew correction roller pair 1103a and 1103b. Here, | Δd Lx −Δd Rx | is expressed by the following equation.

| Δd Lx −Δd Rx | ≈k (| F Lx V L −F Rx V R | / F max ) τ ·· (3)

Here, during the skew correction of the sheet, the forces F Lx and F Rx applied to the pair of skew correction rollers 1103a and 1103b are proportional to the conveyance load F BT to the sheet, so that the skew correction accuracy is improved. Therefore, it is necessary to reduce the conveyance load FBT to the sheet.

For this reason, generally, when correcting the skew of the sheet, as shown in FIG. 20, the transport rollers 1104 positioned upstream of the pair of skew correction rollers 1103a and 1103b are all separated and the transport guide is straight. I try to make it a pass. Thereby, the conveyance load FBT to the sheet can be reduced.

JP-A-4-277151

However, when the conveyance guide of the resist unit is made straight in this way, the sheet conveyance device becomes large. Therefore, in order to reduce the size of the sheet conveying apparatus, it is necessary to arrange a bent conveyance guide upstream of the registration unit. However, when the bent conveyance guide is arranged in this way, a conveyance load F to the sheet is required. BT becomes very large.

Furthermore, the basis weight of sheets used in recent years varies from a thin paper of about 50 g / m 2 to a thick paper of 300 g / m 2 or more, and the size of the sheet ranges from a small size of a postcard to a large size of about 330 mm × 488 mm. Diversified. In particular, when correcting skew and misalignment of a large-size sheet of thick paper having a large inertia force, the conveyance load FBT to the sheet is further increased.

As a result, the forces F Lx and F Rx applied to the skew correction roller pair 1103a and 1103b during skew correction also increase in proportion, and the difference between the forces F Lx and F Rx applied during correction increases simultaneously. If the difference between the forces F Lx and F Rx applied at the time of correction increases as described above, the difference in slip amount also increases. Therefore, the skew correction accuracy deteriorates due to the slip of the skew correction roller pair 1103a and 1103b. Will occur.

  On the other hand, as described above, in order to transport various types of paper such as coated paper and embossed paper in addition to plain paper, in the conventional sheet feeding device, air is blown onto a stack of stacked sheets and sheets 1 In many cases, so-called air feeding is used in which the sheets are forcibly separated one by one.

  Here, in the case of such air feeding, it becomes possible to separate and feed various stacked sheets one by one, but the sheet blown with air regulates the position in the width direction of the sheet. When there is no restriction member, there is a case where the skew is greatly performed.

Then, the corrected in this manner greatly skewed sheets at short distances (short), necessary to increase skew correction roller pair 1103a, during the correction of 1103b sheet conveying speed V L, the difference between V R There is. In other words, it is necessary to reduce the turning radius R ROT .

However, thus skew correction roller pair 1103a, the sheet conveying speed V L at the time of correction of 1103b, the larger the difference between V R, skew correction roller pair 1103a, the force F Lx applied during correction 1103b, the F Rx The difference also increases at the same time. As a result, the difference in slip amount between the skew correction roller pair 1103a and 1103b increases, and the skew correction accuracy deteriorates.

  Accordingly, the present invention has been made in view of such a current situation, and an object thereof is to provide a sheet conveying apparatus, an image forming apparatus, and an image reading apparatus capable of correcting skew of a sheet with high accuracy. To do.

  The present invention relates to a sheet conveying apparatus that conveys a sheet, a sheet conveying path for conveying a sheet, a skew correction unit that is provided in the sheet conveying path and corrects the skew of the sheet, and detects the skew of the sheet. A first skew detection unit that detects the skew of the sheet, and a second skew detection unit that is provided downstream of the first skew detection unit and detects the skew of the sheet. The skew correction unit performs the first skew correction based on the detection information of the skew detection unit, and the second skew detection unit performs the first skew correction on the sheet on which the first skew correction has been performed. A second skew correction is performed by the skew correction unit based on detection information.

  As in the present invention, after the first skew correction is performed on the sheet by the skew correction unit, the second skew correction is performed on the sheet on which the first skew correction has been performed. The skew of the sheet can be corrected with high accuracy.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a printer that is an example of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 1000 denotes a printer, and the printer 1000 includes a printer main body 1001 and a scanner 2000 disposed on the upper surface of the printer main body 1001.

  Here, the scanner 2000 that reads a document includes a scanning optical system light source 201, a platen glass 202, and a document pressure plate 203 that opens and closes. An image reading unit 2001 including a lens 204, a light receiving element (photoelectric conversion element) 205, an image processing unit 206, a memory unit 208 for storing image processing signals processed by the image processing unit 206, and the like. I have.

  When reading the original, the original (not shown) placed on the platen glass 202 is read by irradiating light with the scanning optical system light source 201. Then, the read document image is processed by the image processing unit 206, converted into an electrically encoded electric signal 207, and transmitted to the laser scanner 111 a serving as an image forming unit. Note that the image information processed and encoded by the image processing unit 206 can be temporarily stored in the memory unit 208 and transmitted to the laser scanner 111a as required by a signal from the controller 120.

  The printer main body 1001 includes a sheet feeding device 1002, a sheet conveying device 1004 that conveys the sheet S fed by the sheet feeding device 1002 to the image forming unit 1003, and a controller 120 that is a control unit for controlling the printer 1000. Etc.

  Here, the sheet feeding apparatus 1002 includes a separation unit including a cassette 100, a pickup roller 101, a feed roller 102, and a retard roller 103. The sheets S in the cassette 100 are separated and fed one by one by the action of the pickup roller 101 that moves up and down / rotates at a predetermined timing and the separation unit.

  The sheet conveying apparatus 1004 includes a vertical path roller pair 105 (105a, 105b), an assist roller pair 10, first and second skew correction roller pairs 21, 22, and a registration roller pair 30.

  The sheet S fed from the sheet feeding apparatus 1002 is guided by the pair of vertical path rollers 105 to the registration unit 1 after passing through a sheet conveyance path 108 constituted by guide plates 106 and 107 having curved upper portions. Thereafter, the sheet S is conveyed to the image forming unit 1003 after skew correction is corrected in the registration unit 1 as described later.

  The image forming unit 1003 is of an electrophotographic type, and includes a photosensitive drum 112 as an image carrier, a laser scanner 111a as an image writing unit, a developing device 114, a transfer charger 115, a separation charger 116, and the like. .

  When forming an image, first, the laser beam from the laser scanner 111a is folded back by the mirror 113 and applied to the exposure position 112a on the photosensitive drum rotating in the clockwise direction, so that a latent image is formed on the photosensitive drum. It is formed. Further, the latent image formed on the photosensitive drum in this way is thereafter visualized as a toner image by the developing device 114.

Next, the toner image on the photosensitive drum that has been visualized in this manner is then transferred to the sheet S by the transfer charger 115 in the transfer unit 112b. The distance from the laser beam irradiating position 112a on the photosensitive drum 112 to the transfer portion 112b has a l 0.

  Further, the sheet S on which the toner image is transferred in this manner is electrostatically separated from the photosensitive drum 112 by the separation charger 116 and then conveyed to the fixing device 118 by the conveyance belt 117 to fix the toner image. Thereafter, the paper is discharged by a discharge roller 119.

  In FIG. 1, reference numeral 131 denotes a registration sensor provided downstream of the registration roller pair 30, and the registration sensor 131 detects the sheet S that has passed through the registration roller pair 30. When the registration sensor 131 detects the sheet S that has passed the registration roller pair 30, based on this detection signal, the controller 120 sends a sheet leading edge signal (image destination signal) to the laser scanner 111a, for example, after T seconds, as will be described later. Thereby, irradiation of the laser beam by the laser scanner 111a is started.

  In this embodiment, the printer main body 1001 and the scanner 2000 are separate, but the printer main body 1001 and the scanner 2000 may be integrated. In addition, the printer main body 1001 functions as a copying machine when a processing signal of the scanner 2000 is input to the laser scanner 111a, and functions as a FAX when a FAX transmission signal is input. Furthermore, if an output signal of a personal computer is input, it functions as a printer.

  Conversely, if the processing signal of the image processing unit 206 of the scanner 2000 is transmitted to another FAX, it functions as a FAX. If the scanner 2000 is equipped with an automatic document feeder 250 as shown by a two-dot chain line instead of the original pressure plate 203, the original can be automatically read.

  Next, the resist unit 1 will be described.

  As shown in FIG. 2, the registration unit 1 includes an assist roller pair 10, first and second skew correction roller pairs 21 and 22, and a registration roller pair 30 provided in the sheet conveyance path 108. These roller pairs 10, 21, 22, and 30 are rotatably held by a frame (not shown).

  The assist roller pair 10 includes an assist drive roller 10a and an assist driven roller 10b that is detachably pressed against the assist drive roller 10a by a pressure spring (not shown). Here, the assist drive roller 10a is driven in the sheet conveying direction by the assist motor 11, and is shifted in the width direction integrally with the assist driven roller 10b by the assist shift motor 12.

  Further, the assist driven roller 10b is moved in a direction away from the assist driving roller 10a by the assist release motor 14. In FIG. 2, 13 is an assist shift HP sensor for detecting the home position (HP) of the assist drive roller 10a, and 15 is an assist release HP sensor for detecting the home position of the assist driven roller 10b.

  The first and second skew correction roller pairs 21 and 22 constitute a skew correction unit that corrects the skew of the sheet, and a pair is disposed at a predetermined interval in the width direction. Further, the skew correction driving rollers 21a and 22a, the circumferential surfaces of which are partially cut away, and the skew correction driven rollers 21b and 22b that are pressed against the skew correction driving rollers 21a and 22a by a pressure spring (not shown). It is configured.

  Here, the skew correction driving rollers 21a and 22a are independently driven in the sheet conveyance direction by skew correction motors 23 and 24, respectively. Further, on the upstream side in the sheet conveying direction of the first and second skew correction roller pairs 21 and 22, a start sensor for starting the skew correction motors 23 and 24 is arranged in the width direction as shown in FIG. Are arranged at a predetermined interval L.

  When the start sensors 27a and 27b, which are first skew detection units for detecting the skew of the sheet, detect the leading edge of the sheet S, the skew correction motors 23 and 24 are started in synchronization with the detection. The Thus, the sheet is conveyed while being nipped by the skew correction driving rollers 21a and 22a and the skew correction driven rollers 21b and 22b.

  Here, as shown in FIG. 10, which will be described later, the skew correction driving rollers 21a and 22a have a home position where a portion where the peripheral surface is notched faces the skew correction driven rollers 21b and 22b. As a result, the holding of the sheet is released. Further, by releasing the nipping of the sheet in this way, the first and second skew feeding correction roller pairs 21 and 22 are prevented from hindering the sheet conveyance and the sheet width direction shift by the registration roller pair 30 described later. be able to.

  In FIG. 2, reference numerals 25 and 26 denote skew correction HP sensors for detecting the phases of the skew correction drive rollers 21a and 22a. The skew correction HP sensors 25 and 26 are used to detect the skew correction drive rollers. It is detected that 21a and 22a have moved to the home position.

  Further, on the downstream side of the first and second skew correction roller pairs 21 and 22 in the sheet conveying direction, the first and second skews are second skew detection units for detecting the skew of the sheet S. The detection sensors 28a and 28b are arranged at a predetermined interval L in the width direction as shown in FIG. Note that the start sensors 27a and 27b and the first and second skew detection sensors 28a and 28b provided downstream of the start sensors 27a and 27b are photosensitive drums 112 provided on the downstream side in the sheet conveying direction (see FIG. 1). ) Are arranged so as to be parallel to an axis (not shown).

  The registration roller pair 30 is composed of a registration driving roller 30a with a peripheral surface partially cut away, and a registration driven roller 30b that is in pressure contact with the registration driving roller 30a by a pressure spring (not shown).

  The registration driving roller 30a of the registration roller pair 30 is driven by the registration motor 31 in the sheet conveying direction. Thus, the sheet is conveyed while being nipped by the registration roller pair 30 (the registration driving roller 30a and the registration driven roller 30b).

  Here, as shown in FIG. 8, which will be described later, when the registration driving roller 30a is at the home position where the peripheral surface is cut away from the registration driven roller 30b, the nipping of the sheet is released. The In addition, by releasing the nipping of the sheet in this way, it is possible to prevent the registration roller pair 30 from interfering with the skew correction of the sheet by the first and second skew correction roller pairs 21 and 22 described later.

  The registration roller pair 30 is shifted in the width direction by a registration shift motor 33. In FIG. 2, reference numeral 32 denotes a registration HP sensor for detecting the phase of the registration driving roller 30a. The registration HP sensor 32 detects that the registration driving roller 30a has moved to the home position.

  Reference numeral 34 denotes a registration shift HP sensor for detecting a home position in the width direction of the registration roller pair 30. The registration shift HP sensor 34 detects that the registration roller pair 30 has moved to the home position. Reference numeral 35 denotes a lateral registration detection sensor that is provided upstream of the registration roller pair 30 in the sheet conveyance direction and detects a positional deviation in the width direction of the side edge of the sheet S. The lateral registration detection sensor 35 is a predetermined sensor in the width direction. They are arranged at intervals.

  Detection signals (detection information) from these sensors are input to the CPU 121 shown in FIG. 3 provided in the controller 120 (see FIG. 1), and the CPU 121 drives a motor or the like based on the detection signals from these sensors. To control.

By the way, in the present embodiment, when the leading edge of the sheet S is detected at different timings by the activation sensors 27a and 27b as shown in FIG. 4, the CPU 121 determines that the sheet is based on the detection time difference Δt 1 between the activation sensors 27a and 27b. Calculate the skew amount at the tip.

After this, for example, when the activation sensor 27a detects the sheet first, the control parameter is used to correct the skew by decelerating the first skew correction roller pair 21 (skew correction motor 23). The correction time T 1 and the deceleration speed ΔV 1 are calculated so as to satisfy the following formula.

  Further, the speed of the assist roller pair 10 in the sheet conveyance direction is obtained as follows.

From the relationship of FIG. 5, the sheet conveyance speed during correction of the first and second skew correction rollers 21 and 22 is V L , V R , the thrust pitch between the first and second skew correction rollers is L RP , and the sheet When the turning speed (angular speed) at the turning center O of S is ω, the turning speed ω is expressed by the following equation.

Further, assuming that the turning distance from the turning center O of the sheet S to the middle point O ′ between the first and second skew feeding correction roller pairs 21 and 22 is R ROT , the turning distance R ROT is expressed by the following equation. The

R ROT · ω≡ (V L + V R ) / 2

From this equation, the turning distance R ROT is expressed by the following equation.

On the other hand, the sheet conveyance direction speed in the assist roller pair 10 is V ASX , the thrust direction speed is V ASY , and the distance between the first and second skew correction roller pairs 21 and 22 and the assist roller pair 10 is L AS . At this time, the turning distance R AS between the turning center O of the sheet S and the assist roller pair 10 is expressed by the following equation.

Further, when the angle formed between the turning center O of the sheet S and the assist roller pair 10 is θ, and the angle formed with the combined conveyance speed | ωR AS | of the sheet S by the assist roller pair 10 is φ, the angle φ is expressed by the following equation. expressed.

  φ = θ−π / 2

From the above, the sheet conveying direction speed V ASX and the thrust direction speed V ASY of the assist roller pair 10 are represented by the following relational expressions.

Here, if the skew amount is sufficiently small,
Can be approximated.

Therefore, the sheet conveying direction speed V ASX and the thrust direction speed V ASY of the assist roller pair 10 are expressed by the following equations.

Therefore, the deceleration amounts ΔV 1 , ΔV 2 , and ΔV 3 of the respective speeds of the skew correction motor 23, the assist motor 11, and the assist shift motor 12 can be calculated from the following relational expressions.

On the other hand, the skew correction accuracy greatly affects the slip amount difference | Δd Lx −Δd Rx | between the first and second skew correction roller pairs 21 and 22 as described above. Here, the difference | Δd Lx −Δd Rx | between the slip amounts of the first and second skew feeding correction roller pairs 21 and 22 is expressed by the above-described equation (3). Further, the conveying forces FLx and FRx applied to the skew feeding correction roller pair 21 and 22 at the steady speed of the above-described formula (4) are expressed by the above-described formulas (1) and (2).

On the other hand, the conveyance load on the seat S (back tension) F BT, since it is divided into conveying stationary conveying resistance component F BT1 by the guide, the shift conveying resistance component F BT2 occurring during acceleration and deceleration, represented by the following formula The

FBT = FBT1 + FBT2

Here, F BT2 is a proportional expression of a constant k ′ when the acceleration a during the conveyance of the sheet S is assumed, and is expressed by the following expression.

F BT = F BT1 + k'a ( 5)

Further, the sheet S is composed of paper fibers and generally has a property as a viscoelastic plastic body. In particular, when a thick sheet is conveyed at a high speed to the bent conveyance guide section upstream of the resist section, the conveyance load F BT to the sheet Will become very large.

Here, when the sheet conveyance speed is V, the viscosity coefficient is c, and the constant is k ″, the conveyance load FBT to the sheet is expressed by the following equation.

F BT = cV + k "( 6)

From the above, in order to improve the skew correction accuracy, the sheet conveyance speeds V L and V of the first and second skew correction roller pairs 21 and 22 in the skew correction time τ of the above-described formula (3) are used. It is necessary to make the speed difference ΔV of R as small as possible (≈increase the turning radius R ROT ). That is, it is necessary to make the skew correction amount of the sheet S to be corrected as small as possible.

In addition, the difference between the forces F Lx and F Rx applied to the first and second skew correction roller pairs 21 and 22 in the skew correction time τ of the above-described equation (3) needs to be small at the same time. For this purpose, it is necessary to reduce the sheet conveyance speed difference ΔV and increase the turning radius R ROT from the equations (1) and (2) described above.

Furthermore, from the above-described equation (5), the acceleration a during correction of the first and second skew feeding correction roller pairs 21 and 22 must be made as small as possible. Further, from the above equation (6), in order to reduce the transport load F BT, the sheet conveying speed V L of the skew correction roller pair 21, 22 should be as small as possible V R. On the other hand, in order to reduce the size of the apparatus, the control time τ must be as small as possible.

  For this reason, in the present embodiment, as shown in FIG. 6A, the skew of the sheet S is not corrected at one time by one skew correction, but (b) of FIG. As shown in (2), the skew correction is performed twice with different settings. As a result, the skew of the sheet S skewed greatly is corrected with high accuracy.

  More specifically, the first skew correction is set to a rough skew correction accuracy setting that makes a large sheet S skew as short as possible and within a predetermined amount in a short time. In the second skew correction, a skew feeding amount equal to or less than a predetermined amount of the sheet S is set as long as possible with a correction conveyance path and a correction time as much as possible, and a highly accurate skew correction accuracy setting is performed. That is, the skew correction amount of the sheet in the first skew correction is set to be larger than the skew correction amount of the sheet in the second skew correction.

For this reason, the transport speed in the first skew correction is V 0 , the transport speed difference is ΔV, the acceleration is a, the correction time is T, the transport speed in the second skew correction is V 0 ′, and the transport speed difference Where ΔV ′, acceleration a ′, and correction time T ′, parameters are set as follows.

V 0 »V 0 ', ΔV»ΔV' , a»a ', T«T' (7)

  Next, a sheet skew correction operation in the registration unit 1 that corrects sheet skew by two skew corrections having different settings will be described with reference to a flowchart shown in FIG.

  The sheet S fed from the cassette 100 is conveyed to the assist roller pair 10 by the vertical pass roller pair 105. When the sheet S reaches the assist roller pair 10, the CPU 121 first separates the vertical pass roller pair 105 by a roller release motor (not shown) as necessary for each sheet size, and releases the nip of the vertical pass roller pair 105. (Step 1).

  Next, when the leading edge of the sheet S conveyed by the assist roller pair 10 is detected by the activation sensors 27a and 27b and the activation sensors 27a and 27b are turned on (Y in step 2), the inclination is based on the activation sensors 27a and 27b. The row correction motors 23 and 24 are started (step 3). Then, when the skew feeding correction motors 23 and 24 are activated by such skew feeding correction roller pair activation control, the skew feeding correction driving rollers 21a and 22a rotate in the direction of arrow A in FIG.

  When the skew correction driving rollers 21a and 22a rotate in this way, the skew correction driven rollers 21b and 22b, which have been released from the pressure contact with the skew correction driving rollers 21a and 22a, are inclined as shown in FIG. The line correction drive rollers 21a and 22a are pressed against each other. As a result, the sheet S can be conveyed, and the CPU 121 then starts the first skew correction control.

Here, in the first skew correction control, first, based on the difference in detection timing by the start sensors 27a and 27b, the CPU 121 performs various control parameters for performing skew correction, such as a sheet conveyance speed V 0 and a conveyance speed difference. ΔV, acceleration a, and correction time T are calculated. Based on this, the control amount of each motor is calculated (step 4).

For example, the skew correction motor 24 that drives the second skew correction roller 22 on the delay side of the sheet is controlled to maintain the sheet conveyance speed at V 0 as shown in FIG. As for the skew correction motor 23 for driving the first skew correction roller 21 on the preceding side of the sheet, as shown in FIG. 9B, the sheet is conveyed in the first skew correction section T1. The speed is controlled so as to decelerate by ΔV 1 from V 0 at acceleration a 1 .

The first skew correction is performed by the second skew correction roller 22 in which the sheet conveyance speed is maintained at V 0 and the first skew correction roller 21 decelerated by ΔV 1 . At the end of the skew correction section, the skew correction motor 23 is controlled to re-accelerate the sheet of the first skew correction roller 21 to the transport speed V 0 and prepare for skew correction of the next transported sheet. .

At the same time, the assist motor 11 changes the sheet conveying speed from V 0 to the acceleration a 2 as shown in FIG. 9C so that the sheet does not bend between the decelerated first skew feeding correction roller 21. Is reduced by ΔV 2 and re-accelerated to the conveyance speed V 0 at the end of the skew correction section. Further, the assist shift motor 12 accelerates to ΔV 3 at an acceleration a 3 so as not to hinder the turning of the sheet at the time of skew correction by the first and second skew correction rollers 21 and 22, and the skew correction section ends. Sometimes stop.

Thus, the skew correction motors 23, 24, the assist motor 11, by controlling the assist shift motor 12 (step5), the skew correction interval T 1, performing the first skew correction. As a result, as shown in FIG. 4 described above, the skewed sheet S is largely corrected as indicated by S ′. When such first skew correction is performed, the roller phases of the skew correction drive rollers 21a and 22a are the same.

Next, after the first skew correction of the sheet S is completed, the skew correction motor 23 as shown in FIG. 9 is used to reduce the transport load FBT so as to improve the skew correction accuracy as described above. , 24, controls the assist motor 11 decelerates the sheet conveying speed from V 0 to V 0 '. Thereafter, as shown in FIG. 4, the first and second skew detection sensors 28a and 28b are detected, and the first and second skew detection sensors 28a and 28b are turned ON (Y in step 6).

  Then, the CPU 121 detects the skew amount of the sheet S based on the difference between the detection timings of the first and second skew detection sensors 28a and 28b, and calculates the control amount of each motor based on this (step 7).

For example, the skew feeding correction motor 24 that drives the second skew feeding correction roller 22 on the delay side of the sheet is controlled to maintain the sheet conveyance speed at V 0 ′, as shown in FIG. As for the skew correction motor 23 for driving the first skew correction roller 21 on the preceding side of the sheet, as shown in FIG. 9B, the sheet is conveyed in the second skew correction section T2. The speed is controlled so as to decelerate by ΔV 1 ′ from V 0 ′ with acceleration a 1 ′.

Then, the second skew correction is performed by the second skew correction roller 22 in which the sheet conveyance speed is maintained at V 0 ′ and the first skew correction roller 21 decelerated by ΔV 1 ′. At the end of the skew correction section, the skew correction motor 23 is controlled to re-accelerate the sheet on the first skew correction roller 21 to the transport speed V 0 ′ and to correct the skew of the next transported sheet. Prepare.

At the same time, as shown in FIG. 9C, the assist motor 11 decelerates the sheet conveyance speed from V 0 ′ by the acceleration a 2 ′ by ΔV 2 ′, and reaches the conveyance speed V 0 ′ at the end of the skew correction section. Re-accelerate. Assist shift motor 12 accelerates 'by [Delta] V 3' acceleration a 3 to be stopped during the skew correction section end.

Thus, the skew correction motors 23, 24, the assist motor 11, by controlling the assist shift motor 12 (step8), the skew correction interval T 2, performing the second round of skew correction. As a result, as shown in FIG. 4 described above, the sheet S ′ whose skew has been corrected by the first skew correction is completely skew-corrected as indicated by S ″.

  Next, the sheet S whose skew has been corrected by the first and second skew correction roller pairs 21 and 22 by such second skew correction control is conveyed to the registration roller pair 30. Then, the CPU 121 starts the registration motor 31 with reference to the delay side of the first and second skew detection sensors 28a and 28b, that is, the second skew detection sensor 28b (step 9).

  Here, when the registration motor 31 is activated by such registration roller pair activation control, the registration drive roller 30a of the registration roller pair 30 rotates in the direction of arrow A in FIG. When the registration driving roller 30a rotates in this way, the registration driven roller 30b, which has been released from the pressure contact with the registration driving roller 30a, is pressed against the registration driving roller 30a as shown in FIG. Can be transported.

  When the sheet S is conveyed by the registration roller pair 30, the skew correction driving rollers 21a and 22a that have been in pressure contact with the skew correction driven rollers 21b and 22b so far move to the home position as shown in FIG. , Away from the skew correction driven rollers 21b and 22b. When the skew correction HP sensors 25 and 26 detect that the skew correction drive rollers 21a and 22a have reached the separated positions as described above, the CPU 121 stops the skew correction motors 23 and 24, respectively (step 10). .

  Next, after such skew correction roller HP stop control is completed, the registration sensor 131 detects the leading edge of the sheet S conveyed by the rotation of the registration roller pair 30. When the registration sensor 131 that detects the leading edge of the sheet S is turned ON (Y in step 11), the side edge position of the sheet S is simultaneously detected by the lateral registration detection sensor 35 as shown in FIG. 11 (step 12).

  Here, as shown in FIG. 12, a time difference Δt3 between the detection timing of the registration sensor 131 and the timing (ITOP) at which the photosensitive drum 112 is irradiated with the laser beam, that is, the leading registration, which is a deviation in the sheet conveyance direction of the sheet. Ask.

Then, based on this time difference Δt 3, the deceleration speed ΔV 4 and the shift time T of the registration motor 31 and the assist motor 11 shown in FIGS. 12A and 12C so as to synchronize the leading edge of the image on the photosensitive drum and the leading edge of the sheet. 3 is calculated (step 13).

Further, based on the detection signal of the lateral registration detection sensor 35, the lateral position (image lateral registration position) of the image on the photosensitive drum and the lateral position (lateral registration position) of the sheet S are synchronized (matched). . Therefore, the speed ΔV 5 and the shift time T 4 in the shift direction of the registration shift motor 33 and the assist shift motor 12 shown in FIGS. 12B and 12D are calculated. Thus, the movement amounts of the registration roller pair 30 and the assist roller pair 10 by the registration shift motor 33 and the assist shift motor 12 are calculated (step 14).

  In the leading registration and lateral registration correction control, the registration motor 31, the registration shift motor 33, the assist motor 11 and the assist shift motor 12 are controlled to correct the leading registration and lateral registration of the sheet (step 15). As a result, the sheet S moves as shown in FIG. 11, and the leading edge position and the lateral registration position of the image position on the photosensitive drum 112 and the sheet S can be matched.

  Next, when the shifting operation of the sheet S is completed, as shown in FIG. 12E, the assist release motor 14 is rotated forward (step 16), and the assist driven roller 10a of the assist driven roller 10b of the assist roller pair 10 is in contact with the assist drive roller 10a. Release pressure contact. Then, when the nip release of the assist roller pair 10 is detected by the assist release HP sensor 15, the assist shift motor 12 is started (step 17), and the assist roller pair 10 is in a direction opposite to the step 15 described above. Shift to. Thereafter, when the assist shift HP sensor 13 detects the assist roller pair 10 that has been shifted, the assist shift motor 12 is stopped.

At this time, since the assist roller pair 10 is moved in the shift direction by the first and second skew corrections and the lateral registration correction, the assist shift motor 12 is driven in preparation for the next conveyed sheet. controlling, T 5 shifts move drivable maximum moving speed. Then, at the position where the rear end of the sheet S passes through the assist roller pair 10, the assist release motor 14 is rotated in reverse (step 18). As a result, the assist driven roller 10b comes into pressure contact with the assist driving roller 10a again. Thereafter, the T 4 ′ registration shift motor 33 is reversely rotated to return the registration roller pair 30 to HP.

  Next, after such pre-registration HP control, the sheet S conveyed by the registration roller pair 30 is transferred and attracted to the photosensitive drum 112, and then reaches the home position where the registration driving roller 30a is separated from the registration driven roller 30b. (See FIG. 8). When the registration HP sensor 26 detects that the registration driving roller 30a has reached the home position, the skew feeding correction motors 23 and 24 are stopped based on the registration HP sensor 26 (step 19).

  At the same time, the registration shift motor 33 is started as the registration roller HP stop control (step 20), the registration roller pair 30 is shifted in the direction opposite to that of step 15, and the registration roller pair 30 stops when the registration shift HP sensor 34 detects it. .

  Thereafter, by repeating such step 1 to step 20, it is possible to continuously perform the skew correction of the sheet S and the position correction between the image on the drum 112 and the sheet S with high accuracy. In other words, the skew of the sheet S is roughly roughened by the first skew correction, that is, most of the skew of the sheet is corrected to reduce the skew amount of the sheet, and small by the second skew correction. By correcting the skewed sheet S with high accuracy, the skewed sheet S can be corrected with high accuracy.

  As described above, the first and second skew correction roller pairs 21 and 22 perform the first skew correction on the sheet S, and the second sheet S after the first skew correction is performed. By performing the skew correction, the skew of the sheet can be corrected with high accuracy.

  Next, a second embodiment of the present invention will be described.

  FIG. 13 is a diagram illustrating a skew correction driving roller constituting a skew correction roller pair provided in the registration unit of the sheet conveying apparatus according to the present embodiment.

  As shown in FIG. 13, the skew correction driving roller 21a performs the first high-accuracy skew correction on the first outer peripheral surface 211 in contact with the sheet when performing the first rough skew correction. When performing, it has the 2nd outer peripheral surface 212 and the notch part 213 which contact | abut with a sheet | seat.

By the way, at the time of correcting the skew of the sheet, the skew correction is performed by turning the sheet S by the first and second skew correction roller pairs 21 and 22. At this time, the conveyance forces F L and F R from the first and second correction roller pairs 21 and 22 and the conveyance resistance F BT applied to the sheet S are balanced at approximately three points (see FIG. 19).

  However, since the first and second skew correction roller pairs 21 and 22 have a predetermined roller width, the first and second skew correction roller pairs 21 and 22 are sandwiched when the sheet is turned. The seat part is not able to swivel. In this case, as shown in FIG. 14, the sheet S tries to turn in the ω ′ direction opposite to the ω direction within the nip having a predetermined width between the first and second skew feeding correction roller pairs 21 and 22. And

  As a result, a strain H is generated in the sheet S. When such a distortion H occurs, the first and second skew feeding are performed so that the distortion H is eliminated during the skew feeding correction of the sheet S by the first and second skew feeding correction roller pairs 21 and 22. A delicate slip occurs in the nip between the correction roller pair 21 and 22, and the skew correction accuracy deteriorates.

  In the worst case, the sheet Sh shown in FIG. 14 is greatly distorted between the first and second skew correction roller pairs 21 and 22. Such a phenomenon depends on the paper type of the sheet Sh, but tends to occur when the roller widths of the first and second skew correction roller pairs 21 and 22 are large and the pressure contact pressure is high.

  In addition, the first and second skew correction roller pairs 21 and 22 have low roller hardness and a large roller thickness, so that they easily collapse and have a large contact area with the sheet Sh. It is likely to occur when it is high.

  Therefore, in the present embodiment, the first outer peripheral surface 211 is a roller that increases the contact area with the sheet S so as to eliminate the distortion H generated in the sheet Sh and the accompanying deterioration in skew correction accuracy. The thickness and width are large. Further, a knurled groove shape is formed on the surface of the roller so as to be resistant to slipping and durability of paper dust and to increase frictional resistance.

  Further, the second outer peripheral surface 212 has a small roller thickness and width, and the roller surface is polished with high accuracy. By configuring the first outer peripheral surface 211 and the second outer peripheral surface 212 in this way, most of the skew of the sheet can be corrected in the first skew correction.

  In the present embodiment, the first outer peripheral surface 211 has a large roller thickness and width and a knurled groove shape on the roller surface, but if most of the skew of the sheet can be corrected, It only needs to have one of a large roller thickness and width and a knurled groove shape. Also, the second outer peripheral surface 212 only needs to have a small roller thickness and width and one of the roller surfaces polished with high accuracy.

  Next, the first and second skew correction roller pairs 21 and 22 including the skew correction drive roller 21a and the skew correction drive roller 22a having the same configuration as the skew correction drive roller 21a having the above-described configuration. The sheet skew correction operation will be described.

  As shown in FIG. 15, the skew correction driven rollers 21b and 22b constituting the first and second skew correction roller pairs 21 and 22 are corrected by the pressure springs 21c and 22c via the driven roller shaft 20b. It is biased toward the drive roller. Further, pressure arms 21d and 22d are attached to one ends of the pressure springs 21c and 22c. The pressure arms 21d and 22d are pressure adjustments mounted on the motor shafts of the skew feeding correction motors 23 and 24, respectively. The cams 21e and 22e are connected.

  Here, when the skew correction motors 23 and 24 are started, the skew correction drive rollers 21a and 22a rotate in the arrow direction from the stop state shown in FIG. When rotating in this manner, the first outer peripheral surface 211 and the skew correction driven rollers 21b and 22b are in pressure contact with each other as shown in FIG. 15B, and in this state, the first skew correction of the sheet is performed.

  At this time, the skew correction driven rollers 21b and 22b are in pressure contact with the skew correction driving rollers 21a and 22b with the maximum size by the pressure adjusting cams 21e and 22e. That is, the sheet clamping force of the first and second skew feeding correction roller pairs 21 and 22 is maximized. Then, by being conveyed in such a state, the skew of the sheet is greatly corrected.

  Next, after such first skew correction, as shown in FIG. 15C, the second outer peripheral surface 212 and the skew correction driven rollers 21b and 22b are in pressure contact, and in this state, the second sheet The second skew correction is performed. At this time, the skew correction driven rollers 21b and 22b are pressed against the skew correction driving rollers 21a and 22b with a minimum size by the pressure adjusting cams 21e and 22e. Then, by being conveyed in such a state, the skew of the sheet is corrected with high accuracy.

  FIG. 16 is a diagram illustrating a skew correction amount in the skew correction according to the present embodiment.

  Here, in the case of the first skew correction, the first outer peripheral surface 211 has a large roller thickness, width, and pressing force (clamping force), and the roller surface has a knurled groove shape. Is strong. For this reason, even when the skew amount of the sheet S is large, it is possible to correct even the skew variation indicated by the thick broken line to the extent that the skew correction accuracy is deteriorated due to the distortion H of the sheet S.

  In the case of the second skew correction, the second outer peripheral surface 212 has a small correction roller thickness, width, and pressing force, and the roller surface is polished with high accuracy. When it is large, slip occurs. However, when the skew amount of the sheet S is small, there is almost no deterioration in skew correction accuracy due to distortion in the sheet S.

  For this reason, in the case of the first skew correction, the skew of the sheet S is roughly roughened by the first outer peripheral surface 211, and the second skew correction is performed on the sheet S whose skew amount is small. In this case, the skew correction can be performed with high accuracy by performing the skew correction on the second outer peripheral surface 212.

  In the present embodiment, the contact state between the first outer peripheral surface 211 and the sheet of the second outer peripheral surface 212 is changed depending on the thickness of the roller and the surface shape, but the first outer peripheral surface 211 and the second outer peripheral surface 212 are changed. The same effect can be obtained even if the roller material is changed with the outer peripheral surface 212. For example, the material of the first outer peripheral surface 211 may have a larger friction coefficient than the material of the second outer peripheral surface 212.

  In the description so far, the first skew correction and the second skew correction are performed by the same skew correction roller pair 21 and 22, but the present invention is not limited to this. For example, the skew correction unit that corrects the skew of the sheet includes a skew correction roller pair for the first skew correction and a downstream that performs the second skew correction downstream of the skew correction roller pair. You may make it comprise with a side skew correction roller pair. The first skew correction and the second skew correction may be performed by the pair of skew correction rollers for correction.

  Further, in the description so far, the case where the sheet conveying apparatus according to the present invention is used in a printer which is an example of an image forming apparatus has been described, but the present invention is not limited to this. For example, an image reading apparatus shown in FIG. 1 is used so that the image reading unit that reads an image of the sheet conveyed by the sheet conveying device has no inclination and can be accurately aligned in the image reading unit. The present invention can also be applied to the scanner 2000.

1 is a schematic configuration diagram of a printer that is an example of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention. The figure explaining the structure of the resist part provided in the said sheet conveying apparatus. The control block diagram of the said resist part. FIG. 3 is a top view showing a state in which sheet skew is corrected by the registration unit. FIG. 6 is a diagram for explaining operation parameters when the skew of the sheet is corrected by the registration unit. The figure which shows the skew correction amount in the 1st time and the 2nd skew correction by the said registration part. 6 is a flowchart showing sheet skew correction operation by the registration unit. FIG. 6 is a first diagram illustrating sheet skew correction operation by the registration unit. FIG. 3 is a first diagram illustrating a motor operation in the registration unit. FIG. 10 is a second diagram illustrating a sheet skew correction operation by the registration unit. FIG. 6 is a diagram for explaining a leading registration and lateral registration correcting operation by the registration unit. FIG. 6 is a second diagram illustrating the motor operation in the registration unit. FIG. 10 is a diagram illustrating a skew correction driving roller that constitutes a pair of skew correction rollers provided in a registration unit of a sheet conveying device according to a second embodiment of the present invention. Schematic explaining the behavior with the sheet | seat in the said resist part. The figure explaining the skew feeding correction | amendment operation | movement of the sheet | seat by the said registration part. The figure which shows the skew correction amount in the 1st time and the 2nd skew correction by the said registration part. FIG. 10 is a first diagram illustrating a skew correction operation of a conventional sheet conveying apparatus. FIG. 10 is a first diagram illustrating operation parameters in skew correction of a conventional sheet conveying apparatus. FIG. 10 is a second diagram illustrating operation parameters in skew correction of a conventional sheet conveying apparatus. FIG. 9 is a second diagram illustrating a skew correction operation of a conventional sheet conveying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Assist roller pair 10a Assist drive roller 10b Assist driven roller 11 Assist motor 12 Assist shift motor 13 Assist shift HP sensor 14 Assist release motor 15 Assist release HP sensor 21 First skew feeding correction roller pair 21a Skew correction driving roller 211 First Outer peripheral surface 212 second outer peripheral surface 21b skew correction driven roller 22 second skew correction roller pair 22a skew correction drive roller 22b skew correction driven rollers 23 and 24 skew correction motors 25 and 26 skew correction HP sensor 27a, 27b Start sensor 28a, 28b Skew detection sensor 30 Registration roller pair 30a Registration drive roller 30b Registration driven roller 31 Registration motor 32 Registration HP sensor 33 Registration shift motor 34 Registration shift HP sensor 35 Lateral registration detection sensor 120 Controller 121 CP
131 Registration Sensor 1000 Printer 1001 Printer Main Body 1003 Image Forming Unit 2000 Scanner 2001 Image Reading Unit S Sheet

Claims (10)

  1. In a sheet conveying apparatus that conveys a sheet,
    A sheet conveyance path through which the sheet is conveyed;
    A skew correction unit that is provided in the sheet conveyance path and corrects skew of the sheet;
    A first skew detection unit that detects skew of the sheet;
    A second skew detection unit that is provided downstream of the first skew detection unit and detects the skew of the sheet,
    A first skew correction is performed by the skew correction unit on the sheet based on detection information of the first skew detection unit, and the first skew correction is performed on the sheet on which the first skew correction is performed. A sheet conveying apparatus that performs second skew correction by the skew correction unit based on detection information of the second skew detection unit.
  2.   2. The sheet conveying apparatus according to claim 1, wherein a skew correction amount of the sheet in the first skew correction is larger than a skew correction amount of the sheet in the second skew correction.
  3.   The skew feeding correction unit is provided in a width direction orthogonal to the sheet transport direction of the sheet transport path, and is independently driven, and is a pair of skews that correct the skew of the sheet by rotating the sheet while transporting the sheet. The sheet feeding speed of the skew feeding correction roller in the second skew correction is lower than the sheet feeding speed in the first skew correction. The sheet conveying apparatus according to claim 1 or 2.
  4. The skew feeding correction unit is provided in a width direction perpendicular to the sheet transport direction of the sheet transport path, and is independently driven, and a pair of skews that correct the skew of the sheet by rotating while transporting the sheet. Consists of line correction rollers,
    The contact area between the skew correction roller and the sheet in the first skew correction is larger than the contact area between the skew correction roller and the sheet in the second skew correction. The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is configured.
  5. The skew feeding correction unit is provided in a width direction perpendicular to the sheet transport direction of the sheet transport path, and is independently driven, and a pair of skews that correct the skew of the sheet by rotating while transporting the sheet. Consists of line correction rollers,
    The material of the portion of the skew correction roller that contacts the sheet at the time of the first skew correction is larger in friction coefficient than the material of the portion that contacts the sheet at the time of the second skew correction. The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus.
  6. The skew feeding correction unit is provided in a width direction perpendicular to the sheet transport direction of the sheet transport path, and is independently driven, and a pair of skews that correct the skew of the sheet by rotating while transporting the sheet. Consists of line correction rollers,
    The shape of the portion of the skew correction roller that contacts the sheet at the time of the first skew correction has a larger frictional resistance than the shape of the portion that contacts the sheet at the time of the second skew correction. The sheet conveying apparatus according to any one of claims 1 to 3, wherein the sheet conveying apparatus has a shape as follows.
  7. The skew feeding correction unit is provided in a width direction perpendicular to the sheet transport direction of the sheet transport path, and is independently driven, and a pair of skews that correct the skew of the sheet by rotating while transporting the sheet. Consists of line correction rollers,
    The sheet clamping force by the skew feeding correction roller at the time of the first skew correction is larger than the sheet clamping force at the time of the second skew correction. The sheet conveying apparatus of any one of Claims.
  8. The skew feeding correction unit is provided in a width direction perpendicular to the sheet transport direction of the sheet transport path, and is independently driven, and a pair of skews that correct the skew of the sheet by rotating while transporting the sheet. Consists of a row correction roller and a pair of downstream skew correction rollers,
    The skew correction roller performs a first skew correction on the sheet based on detection information of the first skew detection unit, and the sheet on which the first skew correction has been performed. 8. The sheet conveyance according to claim 1, wherein the second skew correction is performed by the downstream skew correction roller based on detection information of a second skew detection unit. 9. apparatus.
  9. The sheet conveying device according to any one of claims 1 to 8,
    An image forming unit for forming an image on a sheet conveyed by the sheet conveying device;
    An image forming apparatus comprising:
  10. The sheet conveying device according to any one of claims 1 to 8,
    An image reading unit for reading an image of a sheet conveyed by the sheet conveying device;
    An image reading apparatus comprising:
JP2007097888A 2007-04-03 2007-04-03 Sheet conveying device, image forming device, and image reading device Pending JP2008254856A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2007097888A JP2008254856A (en) 2007-04-03 2007-04-03 Sheet conveying device, image forming device, and image reading device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2007097888A JP2008254856A (en) 2007-04-03 2007-04-03 Sheet conveying device, image forming device, and image reading device

Publications (1)

Publication Number Publication Date
JP2008254856A true JP2008254856A (en) 2008-10-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
JP2007097888A Pending JP2008254856A (en) 2007-04-03 2007-04-03 Sheet conveying device, image forming device, and image reading device

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Country Link
JP (1) JP2008254856A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011184200A (en) * 2010-02-15 2011-09-22 Canon Inc Image forming apparatus including skew correction mechanism and control method therefor
JP2012116597A (en) * 2010-11-30 2012-06-21 Canon Inc Sheet conveying device, image reader using the same, and image forming apparatus
US8789827B2 (en) 2012-06-22 2014-07-29 Ricoh Company, Ltd. Sheet conveying device, image reading device, and image forming apparatus
JP2015108651A (en) * 2013-12-03 2015-06-11 コニカミノルタ株式会社 Image forming apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011184200A (en) * 2010-02-15 2011-09-22 Canon Inc Image forming apparatus including skew correction mechanism and control method therefor
JP2012116597A (en) * 2010-11-30 2012-06-21 Canon Inc Sheet conveying device, image reader using the same, and image forming apparatus
US8789827B2 (en) 2012-06-22 2014-07-29 Ricoh Company, Ltd. Sheet conveying device, image reading device, and image forming apparatus
JP2015108651A (en) * 2013-12-03 2015-06-11 コニカミノルタ株式会社 Image forming apparatus

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