JP2010215374A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can be shifted even when the assumed input shift amount is larger to the position of the origin. <P>SOLUTION: The image forming apparatus has a shift means 40 (S1) for shifting a paper sheet 8 in the direction orthogonal to the conveying direction by using a cam 42, and shifts the paper sheet 8 by the shift means 40 according to the input shift amount 52 detected by a paper sheet transverse position detection means 17. The shift means 40 is allowed to wait at the position shifted by the amount of the output shift amount 56 subtracted from the assumed input shift amount 53 in advance before shifting the paper sheet 8 (S2-S10). Even in the presence of the assumed input shift amount 53 or the output shift amount, the shift correction to align the print starting position between the paper sheet 8 and the image can be executed without using any motor of high output, or without reducing the correction shift range. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a plotter, and more particularly to an image forming apparatus suitable for a multifunction machine having at least two functions of the copying machine, printer, facsimile machine, and plotter.

In recent years, multicolor image forming apparatuses such as full-color printers and spot color printers have been employed in copying machines, printers, facsimiles, plotters, and the like.
As such a multicolor image forming apparatus, a plurality of photosensitive drums are arranged along the traveling direction of an intermediate transfer belt composed of an endless belt, and different color toners are applied to the electrostatic latent images formed on the respective photosensitive drums. A tandem system in which toner images are formed by adsorption and sequentially transferred onto a transfer belt may be employed.

  By the way, in such an image forming apparatus, the sheets stacked on the sheet feeding apparatus are fed out one by one, and the fed-out sheets are conveyed toward the transfer position of the toner image. At this time, the toner image at the transfer position is transferred. In order to align the position of the sheet and the sheet, the pair of registration rollers in front of the transfer position temporarily stops the sheet, and the pair of registration rollers is driven in time with the toner image conveyed on the transfer belt to bring the sheet to the transfer position. I try to send it in.

In the apparatus prior to image formation, a cam is used to align the print start position in the direction perpendicular to the paper conveyance direction (hereinafter referred to as the horizontal direction) between the conveyed paper and the image. A shift unit that moves in the horizontal direction is provided in the registration roller unit, and after aligning the printing start position of the sheet and the image, there is also a type in which the sheet is conveyed and transferred toward the transfer position of the toner image by a pair of registration rollers (for example (See Patent Document 1).
The transferred paper is conveyed to a fixing unit and is fixed by being pressurized and heated by a fixing unit.

In such an apparatus, the sheet running line is kept constant. At this time, when a plurality of sheets having the same width are fixed, the same position of the fixing means is worn at the edge of the sheet. As a result, there are problems in that the worn portion affects the fixing image quality of the paper and shortens the life of the fixing means such as the fixing belt.
Therefore, in order to reduce the wear of the fixing unit due to the sheet, an image device has been proposed in which a shift unit that shifts the position where the fixing unit enters the nip portion in the lateral direction is provided in front of the fixing unit (for example, (See Patent Document 2).

Here, FIG. 6 shows the relationship between the paper position and the shift amount in the horizontal direction at this time. As shown in the figure, when the paper is transported with reference to the center of the paper transport path, The horizontal position of the paper 50 when shifted in the horizontal direction and conveyed in the center of the paper conveyance path, and the horizontal position of the paper 51 detected by the paper horizontal position detection means 17 in the shift means 40 where the registration roller pair 16 is disposed. A difference is generated.
Therefore, this difference is detected and set as the input shift amount 52. At this time, the shift to the operator side is set to + (positive), and the shift to the counter operator side is set to-(negative).

Usually, there is a tendency in the input shift amount 52 detected for each paper transport path due to differences in the path shape and path length of the paper transport path from each paper feeder (not shown) to the paper lateral position detecting means 17.
Also, depending on the characteristics of the paper such as the paper length, paper width, paper type, and paper thickness, there is a tendency in the input shift amount 52 detected for each paper characteristic.
Therefore, this tendency amount is referred to as an assumed input shift amount 53.
Then, for example, an assumed input shift amount 53 from a specific sheet feeding device (not shown) can be an average value of the detected input shift amounts 52 in 10 sheets fed from the sheet feeding device. That is, the detected input shift amount 52 is obtained by adding the fluctuation shift amount 54 (variation for each sheet) that varies for each sheet to the assumed input shift amount 53.

On the other hand, in the case of the method disclosed in Patent Document 2, when the paper is transported downstream of the shift means 40 in the paper transport direction, the paper may be intentionally shifted to a position shifted from the center of the paper transport path.
Therefore, this position is referred to as an output shift position 55, and this shift amount is referred to as an output shift amount 56. The amount by which the sheet is actually shifted is referred to as a correction shift amount 57.

By the way, in the case of the shift means 40 (FIG. 6) which shifts using the cam currently disclosed by patent document 1, the eccentric amount of a cam becomes the one-way maximum correction shift range. At this time, when the cam rotation angle is in the vicinity of 90 °, the correction shift amount 57 becomes extremely small with respect to the angle (or the drive amount of the motor), and therefore it is not normally used. For example, when the eccentric amount of the cam is 6 mm, the correction shift range is usually set to ± 5 mm.
Here, even if the fluctuation shift amount 54 is within ± 5 mm which is the correction shift range, if the assumed input shift amount 53 is at a position shifted from the center of the sheet conveyance path, the shift means 40 cannot complete the shift correction. For this reason, there is a problem that an error such as a color misregistration or a jam occurs because the print start position does not match.

At this time, if the eccentric amount of the cam is increased in order to increase the correction shift range, a higher output motor is required or the current value of the motor must be increased, resulting in an increase in cost. was there.
On the other hand, when the output shift amount 56 is set as in Patent Document 2 in order to reduce the wear of the fixing means, there is a problem that the correction shift range decreases in one direction.
For example, in the case of the shift means 40 having a correction shift range of ± 5 mm, when the output shift amount 56 is −1 mm, a shift correction of −6 mm to +4 mm is possible in the detected input shift amount 52, and a correction shift range of 5 mm on the + side. Cannot be secured.

Similarly, in a post-processing apparatus equipped with a paper alignment means such as a jogger, an output shift amount 56 (FIG. 6) is used to prevent deterioration of paper alignment and jamming due to misalignment of the paper alignment means and the lateral position of the paper. When is set, there is a problem that the correction shift range decreases in one direction.
SUMMARY OF THE INVENTION The present invention addresses the above-described problems and aims to solve the problems. Accordingly, the object of the present invention is to provide an image forming apparatus capable of shifting even when the assumed input shift amount is larger than the origin position. It is to be.

  In order to solve the above problem, the first means includes a shift means for shifting the paper in a direction orthogonal to the transport direction using a cam, an origin detection means for detecting the origin position of the cam, and the paper At least one sheet conveyance path until the sheet is conveyed to the shift unit; and a sheet lateral position detection unit that detects a lateral position of the sheet. The sheet is detected by the sheet lateral position detection unit by the shift unit. In the image forming apparatus that shifts in accordance with the input shift amount, the shift unit waits in advance at a position different from the origin position before shifting the sheet.

Next, the second means is characterized in that, in the first means, a position different from the origin position is shifted to an assumed input shift amount.
Further, the third means is characterized in that, in the second means, the assumed input shift amount is set for each paper transport path.
Similarly, in the fourth means, in the second means or the third means, the assumed input shift amount is set for each feature of the paper such as paper length, paper width, paper type, paper thickness and the like. Features.
Similarly, in the fifth means, when there is a difference between the assumed input shift amount and the input shift amount detected by the paper lateral position detecting means in any of the second to fourth means. The input shift amount assumed in accordance with the difference is reset.

Similarly, the sixth means is characterized in that, in the first means, a position different from the origin position is shifted in the reverse direction by an output shift amount with respect to the center of the paper transport path. To do.
Similarly, the seventh means is characterized in that, in the sixth means, the output shift amount is a shift amount for reducing wear of a fixing means provided at a subsequent stage of the shift means.
Similarly, in the eighth means according to the sixth means or the seventh means, the output shift amount is a shift amount for improving the paper alignment of the post-processing means provided in the subsequent stage of the shift means. It is characterized by.

Similarly, the ninth means in any one of the first to eighth means shifts a position different from the origin position by an amount obtained by subtracting the output shift amount from the assumed input shift amount. It is characterized by being a position.
Similarly, in any one of the first to ninth means, the tenth means is a position different from the origin position when a position different from the origin position exceeds the correction shift range of the shift means. Is the limit position of the correction shift range.
The eleventh means may be configured to display an operator panel display or the like when the position different from the origin position exceeds the correction shift range of the shift means in any of the first to tenth means. It is characterized by urging service personnel to make adjustments.

  According to the present invention, the assumed input shift amount is changed according to the average value of the already detected input shift amount so that the standby position of the shift means can be changed. Even if the amount exceeds the limit, it is possible to cope with the correction shift range as it is, and as a result, printing of paper and images can be started without using a high-output motor or increasing the motor current value. Position shift correction can be performed.

1 is a schematic configuration diagram illustrating an embodiment of a sheet positioning unit in an image forming apparatus according to the present invention. It is a schematic diagram which shows the structure of the shift means in one embodiment of this invention. It is a schematic diagram for demonstrating operation | movement of the shift means in one embodiment of this invention. 6 is a flowchart for explaining sheet positioning control according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus to which an embodiment of the present invention is applied. FIG. 6 is an explanatory diagram illustrating a relationship between a horizontal paper position and a shift amount in the image forming apparatus.

Hereinafter, an image forming apparatus according to the present invention will be described in detail with reference to embodiments shown in the drawings.
First, the image forming apparatus to which the present invention is applied will be described using the four-color full-color image forming apparatus of FIG. 5 as an example. In this case, as shown in the drawing, along the traveling direction of the transfer belt 10. The four image forming units 1a, 1b, 1c, and 1d are arranged so that yellow (for example, 1a), magenta (same as 1b), cyan (same as 1c), and black (same as 1d) are provided. It corresponds to each color.

  At this time, the image forming units 1a, 1b, 1c, and 1d are respectively photosensitive drums 2a, 2b, 2c, and 2d as image carriers, drum chargers 3a, 3b, 3c, and 3d, exposure devices 4a, 4b, 4c, 4d, developing devices 5a, 5b, 5c, 5d, transfer devices 6a, 6b, 6c, 6d, and cleaning devices 7a, 7b, 7c, 7d, so that, for example, the image forming unit 1a is a yellow image, The image forming unit 1b forms a magenta image, the image forming unit 1c forms a cyan image, and the image forming unit 1d forms an image having a different color from the black image.

Upon receiving an image forming operation start instruction signal from a printing apparatus control device (not shown), the photosensitive drum 2a starts rotating in the direction of arrow B and continues rotating until the image forming operation is completed.
When the photosensitive drum 2a starts rotating, a high voltage is applied to the charger 3a, and negative charges are uniformly charged on the surface of the photosensitive drum 2a.
When the character data or graphic data converted into a dot image from the printing apparatus control apparatus is sent to the image forming apparatus as an on / off signal of the exposure apparatus 4a, laser light is emitted from the exposure apparatus 4a to the surface of the photosensitive drum 2a. A part to be irradiated and a part not to be irradiated are formed.

On the photosensitive drum 2a, when the portion where the charge is reduced by the irradiation of the laser beam from the exposure device 4a reaches the position facing the developing device 5a, the portion where the charge is reduced on the photosensitive drum 2a is negatively charged. The toner is attracted to form a toner image (in this case, a yellow image).
When the toner image formed on the photosensitive drum 2a reaches the transfer device 6a as the primary transfer means, the toner image is rotated in the direction of arrow A by the action of a high voltage applied to the transfer device 6a. The image is transferred onto the transfer belt 10 that is present.
At this time, the toner remaining without being transferred onto the photosensitive drum 2a even after passing through the transfer position (image transfer portion) is cleaned by the cleaning device 7a and is prepared for the next image forming operation.

An image forming operation is performed in the same manner in the image forming unit 1b following the image forming unit 1a, and a toner image (in this case, a magenta image) formed on the photosensitive drum 2b is a high voltage applied to the transfer device 6b. It is transferred onto the transfer belt 10 by the action.
At this time, the timing at which the image formed in the image forming unit 1 a and transferred onto the transfer belt 10 reaches the transfer device 6 b and the toner image formed on the photosensitive drum 2 b are transferred onto the transfer belt 10. By matching the timing, the toner images formed by the image forming unit 1 a and the image forming unit 1 b overlap on the transfer belt 10.
Similarly, a toner image (in this case, a cyan image and a black image) formed by the image forming units 1 c and 1 d is successively superimposed on the transfer belt 10 to form a full-color image on the transfer belt 10.

At the same time when the full-color image reaches the paper transfer unit 9 as the secondary transfer unit, the paper 8 conveyed in the direction of arrow C from the paper feed unit (not shown) of the image forming apparatus reaches the paper transfer unit 9. The full color image on the transfer belt 10 is transferred to the paper 8 by the action of the high voltage applied to the paper transfer device 9. When the paper 8 is conveyed to the fixing device 11, the toner image on the paper 8 is melted and fixed on the paper 8.
In this way, after the full-color image passes through the paper transfer unit 9, residual toner that is not transferred is adhered onto the transfer belt 10. Therefore, the residual toner is removed by cleaning by the belt cleaning mechanism 12.

Therefore, next, the sheet positioning unit in the image forming apparatus according to the present invention will be described with reference to an embodiment.
Here, FIG. 1 shows, as an example, an embodiment in which the present invention is applied to the color image forming apparatus described with reference to FIG. 5. Therefore, although not shown in FIG. When the paper is conveyed in the C direction and reaches the paper transfer device 9, the full-color image on the transfer belt 10 is transferred to the paper 8 by the action of a high voltage applied to the paper transfer device 9, which is melted and fixed by the fixing device 11. This is the same as in the case of the color image forming apparatus shown in FIG.

  At this time, although omitted in FIG. 5, in order to reduce the wear of the fixing device 11 due to the passage of the paper 8 before the paper transfer device 9, as described in FIG. Shift means 40 for shifting the entry position of the paper 8 in the lateral direction is provided, which is shown in FIGS. 1 (a) and 1 (b), where FIG. 1 (a) is a side view. On the other hand, FIG. 1 (b) is a view of FIG. 1 (a) viewed from above except for the transfer belt 10, and is provided with a shift means 40A.

Next, FIG. 2 shows the details of the shift means 40A according to this embodiment. Here, first, the substrate 41 forms a first unit that operates integrally with the registration roller pair 16, In the drawing, it is held so as to be slidable in the vertical direction, that is, in the lateral direction with respect to the conveyance direction of the paper 8, and a shift operation is performed during shift correction.
Then, a resist roller pair 16 and a cam 42 that is rotationally driven by a driving means (not shown), a spring 43 that presses the protrusion 41A of the substrate 41 against the cam 42, and an origin position 46 of the cam 42 are detected. There are provided an origin detection means 44 and a position detection plate member 45 which is attached to the cam 42 and rotates together so that a notch for enabling position detection by the origin detection means 44 is formed.

Therefore, as described above, the registration roller pair 16 forms the first unit with the substrate 41, and a shift operation is performed during shift correction. At this time, the cam 42, the spring 43, the origin detection means 44, and the position detection plate member 45 also form a second unit different from the substrate 41 and the registration roller pair 16. During the shift correction, the first unit operates relative to the second unit. At this time, the relative position of the second unit is fixed.
Then, the cam 42 is moved from the origin position 46 shown in FIG. 2A to the CCW (counterclockwise) direction as shown in FIG. 2B, or CW (clockwise) as shown in FIG. By rotating in the direction, the substrate 41 can be moved from the origin position 46, and the paper 8 can be arbitrarily shifted to one side and the other side in the horizontal direction.

Here, as an example, the eccentric amount of the cam 42 is set to 6 mm, the correction shift range is set to ± 5 mm, and the sheet positioning portion of the image forming apparatus according to this embodiment will be described with reference to FIG.
The sheet positioning unit according to this embodiment includes a gate unit 13 that positions the leading end of the sheet by abutting the sheet 8 that has been transported, and a pair of transport rollers disposed upstream of the gate unit 13 in the sheet transport direction. 15, a registration roller pair 16, a sheet lateral position detection unit 17 disposed downstream of the gate unit 13, a timing roller 18, and a conveyance belt 19.
Here, as described above, the registration roller pair 16 is configured to be movable in the lateral direction. The gate means 13 is driven as the paper is opened and closed, but the lateral relative position is fixed.

First, the gate means 13 is driven to an open position where the paper 8 can pass and a closed position where the paper 8 comes into contact and is positioned.
Further, the conveying roller pair 15 and the registration roller pair 16 are each composed of two roller members configured to be rotatable and contactable / separable by a driving unit (not shown). Each of the two roller members is disposed so as to sandwich the paper 8 on the transport path in the thickness direction, and is driven to a contact position for transporting the paper 8 and a separation position for separating the paper 8 from the paper 8.
Here, in this embodiment, when the registration roller pair 16 is separated, the gate means 13 is configured to close.
The sheet lateral position detecting means 17 functions to detect the position of the sheet 8 in the lateral direction, and is disposed between the sheet transfer device 9 and the gate means 13 on the downstream side in the sheet conveying direction.

Next, the paper positioning control of the image forming apparatus according to this embodiment will be described with reference to the schematic diagram of FIG. 3 and the flowchart of FIG.
First, as shown in FIG. 1, the paper 8 fed out from a paper supply unit (not shown) is conveyed in the direction of arrow C toward the gate means 13 by the conveying roller pair 15 and the like.
Then, before the paper 8 reaches the gate means 13, the substrate 41 of the shift means 40A is moved to the standby position (S1).
At this time, as an example, assuming that the position shifted from the origin position 46 by the assumed input shift amount 53 minutes is the standby position, in this case, the paper 8 is fed to the paper conveyance path with respect to ± 5 mm of the variable shift amount 54. Shift correction can be performed in the center.

When the standby position is shifted from the origin position 46 to the center of the paper transport path in the reverse direction by the output shift amount 56, the output is output with respect to the detected input shift amount 52 ± 5 mm. Shift correction to the shift position 55 becomes possible.
This will be described with reference to FIG.
First, FIG. 3 (a) is the same as FIG. 2 (a) and shows a state where the shift means 40A is at the origin position 46 (assumed to be the standby position 0).
Next, FIG. 3B shows a state in which the standby position is set to +1 mm when the output shift amount 56 is −1 mm.

If the detected input shift amount 52 is −5 mm, the shift correction to the output shift position 55 can be performed correctly by shifting the substrate 41 of the shift means 40A by +4 mm as shown in FIG. it can.
When the detected input shift amount 52 is +5 mm, as shown in FIG. 3 (d), the substrate 41 of the shift means 40A is shifted by -6 mm to correct the shift to the output shift position 55. be able to.
On the other hand, when the standby position is set to a position shifted from the origin position 46 by an amount obtained by subtracting the output shift amount 56 from the assumed input shift amount 53, as shown in FIG. The shift can be corrected to the output shift position 55 with respect to ± 5 mm.

The transported paper 8 has its leading end abutted against the gate means 13, and the rear end side of the paper 8 is fed downstream by the transport roller pair 15 from the abutted state. Is done.
By the excessive feeding in the state of being abutted against the gate means 13, the oblique shift at the leading edge of the paper 8 is corrected.
In this state, the registration roller pair 16 is closed and the paper 8 is brought into pressure contact with each other, whereby the leading end of the paper 8 is positioned at the position of the gate means 13.
Subsequently, the gate means 13 is opened to retract from the conveyance path, and the conveyance roller pair 15 is separated to return the sheet 8 to a straight state. That is, the positional deviation on the upstream side of the registration roller pair 16 is also corrected.

From this state, the registration roller pair 16 has a predetermined timing, that is, the front end in the belt rotation direction of the toner image on the transfer belt 10 and the front end in the conveyance direction of the paper 8 in time with the toner image conveyed by the transfer belt 10. The paper 8 is started to be conveyed in the direction of arrow C at the timing when the predetermined position of the copy coincides (S2).
Next, the paper 8 is conveyed to the paper horizontal position detecting means 17, the horizontal position of the paper 8 is detected (S3), and if the detected input shift amount 52 is subtracted from the output shift amount 56, the subtracted value is shifted. The correction shift amount 57 of the means 40A is obtained.
Next, it is checked whether or not the correction shift amount 57 of the shift means 40A is within the correction shift range (S4).

First, when the result is NO, that is, when the correction shift amount 57 of the shift means 40A is outside the correction shift range, that is, when the correction shift amount 57 exceeds ± 5 mm in this embodiment, the output shift is performed. The paper 8 cannot be shifted to the amount 56. Therefore, in this case, the jam is detected here and the printing is finished (S5). Thereafter, a message is displayed on the operator panel so as to set the lateral position of the sheet feeding device (S6. Therefore, in this case, the operator or service person performs the resetting (S7).
On the other hand, if the result of the processing of S4 is YES, that is, if the correction shift amount 57 of the shift means 40 is within the correction shift range, the next detected input shift amount 52 is compared with the assumed input shift amount 53 (S8).

If the result of S8 is NO, that is, if it is not different, the process proceeds to S10 as it is. Here, if the result is YES, that is, if the result is different, the assumed input shift amount 53 is corrected (S9).
Specifically, the average position of the input shift amounts 52 detected for the latest 10 sheets is set as the assumed input shift amount 53 of the subsequent sheet.
Then, the shift correction is performed by shifting the sheet 8 by the correction shift amount 57 (S10). Thereafter, when printing is continuously performed (NO in S11), the process returns to S1 before the subsequent sheet reaches the gate unit 13, and the shift unit 40 is moved to the standby position.

  As a result, before shifting the paper 8, the shift means 40A shifts the position shifted by the amount obtained by subtracting the output shift amount 56 from the presumed input shift amount 53, that is, the detected input shift amount 52 is -5 mm. In this case, as shown in FIG. 3 (c), by shifting the substrate 41 of the shift means 40A by +4 mm, it is made to stand by at the output shift position 55, and when the detected input shift amount 52 is +5 mm, As shown in FIG. 3 (d), by shifting the substrate 41 of the shift means 40A by -6 mm, it is also made to stand by at the output shift position 55, so that the input shift amount is initially assumed. Even when the input shift amount is exceeded, the print start position of the paper and the image can be matched.

Therefore, according to this embodiment, since the input shift amount is assumed and the standby position of the cam 42 is changed according to the input shift amount, the sheet position can be shifted by an amount larger than the eccentric amount of the cam 42. As a result, the shift correction of the printing start position of the paper and the image can be performed without using a high output motor or increasing the current value of the motor.
When the input shift amount detected at this time is different from the assumed input shift amount, in the above embodiment, the input shift amount applied to the next sheet is changed before the correction shift. If it is before being conveyed, it may be changed after the correction shift.
Further, the correction of the assumed input shift amount may be performed for each sheet of paper 8, and the average of the previous 10 sheets may be used as the subsequent assumed input shift amount for the above embodiment.

Although not described here, in the case of the above embodiment, the correction of the assumed input shift amount is performed when it is clear that the succeeding sheet is a sheet different from the preceding stage, for example, when the sheet tray is different. Not applicable. When the tray changes, processing is started as the first sheet at that time.
Although not particularly described in the description of the above embodiment, the detection means such as the paper lateral position detection means 17 and the origin detection means 44 is a reflective sensor such as CIS, and detects the end in hardware. It can be realized by various sensors such as an end detection member and a two-dimensional reading sensor.

1a, 1b, 1c, 1d Image forming unit 2a, 2b, 2c, 2d Photosensitive drum 3a, 3b, 3c, 3d Drum charger 4a, 4b, 4c, 4d Exposure device 5a, 5b, 5c, 5d Developer 6a, 6b , 6c, 6d Transfer device 7a, 7b, 7c, 7d Cleaning device 8 Paper 9 Paper transfer device 10 Transfer belt 11 Fixing device 12 Belt cleaning mechanism 13 Gate means 15 Conveying roller pair 16 Registration roller pair 17 Paper lateral position detection means 18 Timing Roller 19 Conveyor belt 40 Shift means (prior art)
40A shift means (embodiment of the present application)
41 Substrate 41A Protrusion (projection of substrate 41)
42 Cam 43 Spring 44 Origin detecting means 45 Position detecting plate member (member which rotates together with the cam 41)
46 Origin position 50 Paper when transported in the center of the paper transport path 51 Paper detected by the paper lateral position detection means 52 Detected input shift amount 53 Assumed input shift amount 54 Fluctuating shift amount 55 Output shift position 56 Output shift amount 57 Correction shift amount 58 Paper without variable shift amount 59 Paper at output shift position

JP 2008-24507 A JP 2006-72246 A

Claims (11)

Shift means for shifting the paper in a direction orthogonal to the conveyance direction using a cam, origin detection means for detecting the origin position of the cam, and at least one paper conveyance until the paper is conveyed to the shift means In an image forming apparatus, comprising: a path; and a sheet lateral position detecting unit configured to detect a lateral position of the sheet, wherein the sheet is shifted by the shift unit according to an input shift amount detected by the sheet lateral position detecting unit.
An image forming apparatus characterized in that the shift unit waits in advance at a position different from the origin position before shifting the sheet. The image forming apparatus according to claim 1,
An image forming apparatus, wherein a position different from the origin position is a position shifted by an assumed input shift amount. The image forming apparatus according to claim 2.
The assumed input shift amount is set for each sheet conveyance path. The image forming apparatus according to claim 2 or 3,
The assumed input shift amount is set for each paper feature such as a paper length, a paper width, a paper type, and a paper thickness. The image forming apparatus according to any one of claims 2 to 4,
In the case where there is a difference between the assumed input shift amount and the input shift amount detected by the paper lateral position detecting means, the assumed input shift amount is reset according to the difference. apparatus. The image forming apparatus according to claim 1,
An image forming apparatus characterized in that a position different from the origin position is a position shifted in the reverse direction by an output shift amount with respect to the center of the sheet conveyance path. The image forming apparatus according to claim 6.
The image forming apparatus according to claim 1, wherein the output shift amount is a shift amount for reducing wear of a fixing unit provided at a subsequent stage of the shift unit. The image forming apparatus according to claim 6 or 7,
The image forming apparatus according to claim 1, wherein the output shift amount is a shift amount for improving paper alignment of a post-processing unit provided at a subsequent stage of the shift unit. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus, wherein a position different from the origin position is shifted by an amount obtained by subtracting an output shift amount from an assumed input shift amount. The image forming apparatus according to any one of claims 1 to 9,
An image forming apparatus, wherein when a position different from the origin position exceeds a correction shift range of the shift means, a position different from the origin position is set as a limit position of the correction shift range. The image forming apparatus according to any one of claims 1 to 10,
An image forming apparatus characterized in that, when a position different from the origin position exceeds a correction shift range of the shift means, an operator or a serviceman is prompted to make an adjustment by an operator panel display or the like.

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