JP2001294369A - Double-sided image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To further improve the printing speed in duplex continuous printing, reduce the decrease in printing speed in duplex continuous printing with different paper sizes, and to improve the printing speed even in duplex continuous printing with greatly different paper widths. Provided is a double-sided image forming apparatus capable of performing stable printing in which skew and jam are prevented. A reversing roller for conveying a sheet by a sheet reversing mechanism, a re-feeding roller for conveying a sheet to join the sheet from a re-feeding mechanism to an image forming unit, A reversing roller 17, a D-cut roller 18, a two-sided conveying roller 19 and a re-feeding roller 21 are provided with a D-cut roller 18 and a two-sided conveying roller 19 for conveying the sheet to the re-feeding mechanism via the movable plate 22. ,
Each is driven independently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided image forming apparatus having a double-sided reversing mechanism and a paper re-feeding mechanism for performing double-sided printing.

[0002]

2. Description of the Related Art From the viewpoint of resource and environmental protection, a double-sided image forming apparatus for printing both the first and second sides of a recording sheet has been commercialized. In double-sided printing, printing on the second side is achieved by providing a paper reversing mechanism that reverses the paper on which the first side has been printed after printing the first side and a paper re-feeding mechanism that re-feeds the paper. are doing.

[0003] The apparatus has a function of correcting a sheet that has been displaced in the main scanning direction due to conveyance of a sheet, further changes the timing of performing the correction in the main scanning direction according to the sheet width, and controls the sheet conveyance speed. It is devised to prevent a reduction in printing speed by increasing the speed depending on the paper length (see JP-A-9-40303). Further, a contrivance is made to prevent conveyance failure at the time of high-speed printing by performing conveyance by monitoring the home position in the notch rotating body (see Japanese Patent Application Laid-Open No. 11-246131).

When the paper size (paper width) differs between the preceding paper and the succeeding paper, the timing of correcting the main scanning direction of the paper and the combination of the paper transport speeds are changed, so that the continuous paper of different paper sizes is changed. The device is designed to enable double-sided printing (see Japanese Patent Application Laid-Open No. 2000-75759).

[0005]

However, the paper transport speed is increased in accordance with the paper length (Japanese Patent Laid-Open No. 9-40303).
In this case, the preceding paper and the succeeding paper are simultaneously conveyed by the same conveying means. Therefore, when the preceding paper is being conveyed at low speed on both sides, the succeeding paper cannot be speeded up, and the printing speed is reduced. There was a problem that led to a decrease.

Further, in the case of continuous double-sided printing in which the paper size (paper width) differs between the preceding paper and the succeeding paper, the combination of the timing for correcting the paper main scanning direction and the paper transport speed is changed (Japanese Patent Laid-Open No. 2000-75759). In this case, it is necessary to reduce the transport speed of the succeeding sheet so that the sheet moves into the entrance of the lateral registration movable plate after the movement of the lateral registration movable plate adjustment position for correcting the main scanning direction of the subsequent sheet. Here, since the preceding sheet and the succeeding sheet are simultaneously conveyed by the same conveying means, the conveying speed of the simultaneously conveyed preceding sheet is also reduced, which causes a problem that the printing speed is reduced.

[0007] In recent years, the size of paper that can be printed has been diversified, and the difference in paper width between different paper sizes has also increased. In the case of continuous double-sided printing in which such a difference in the sheet width is large, even if the transport speed is reduced to the re-feeding speed, the movement of the horizontal registration movable plate adjustment position for correcting the sheet main scanning direction of the subsequent sheet is performed. In time, there has been a problem that sufficient correction in the main scanning direction cannot be performed and skew or a jam occurs.

Therefore, an object of the present invention is to improve the printing speed in continuous printing on both sides in view of the above problems,
It is an object of the present invention to provide a double-sided image forming apparatus capable of reducing a decrease in printing speed during continuous printing on both sides of different paper sizes and performing stable printing with skewed paper and jams prevented even in continuous printing on both sides of paper having greatly different sheet widths. is there.

[0009]

In order to achieve the above object, a double-sided image forming apparatus according to the present invention comprises a sheet reversing mechanism for drawing a sheet into a reversing conveyance path and reversing the sheet and joining the reversed sheet to an image forming section. A double-sided image forming apparatus provided with a re-feeding mechanism for correcting the position of the inverted sheet in the main scanning direction; a first sheet conveying means for conveying the sheet by the sheet reversing mechanism; A second sheet conveying unit that conveys the sheet to join the sheet from the re-feeding mechanism to the image forming unit; and a sheet conveying unit that conveys the sheet from the sheet reversing mechanism to the re-feeding mechanism via the correction unit. And a third sheet conveying means, wherein the first sheet conveying means, the second sheet conveying means, and the third sheet conveying means
It is characterized by being driven independently of each other.

[0010] The correcting means may include a horizontal registration movable plate in contact with an end portion of the paper in the main scanning direction, a moving means for moving the horizontal registration movable plate, and a position of the horizontal registration movable plate in the main scanning direction of the paper. And paper position adjustment control means for controlling the moving means so as to perform the correction operation.

In addition, there is provided a paper transport speed control means for controlling the transport speed of the first paper transport means, the second paper transport means, and the third paper transport means based on the paper size of the paper to be transported. It is characterized by the following.

Further, there is provided a paper transport speed control means for controlling the transport speeds of the first paper transport means, the second paper transport means and the third paper transport means based on the paper length of the paper to be transported. It is characterized by the following.

Further, the invention is characterized in that the start timing of the correcting operation of the position in the main scanning direction of the sheet by the correcting means is changed based on the sheet width of the sheet to be conveyed.

In the case where a preceding sheet having a different sheet size is being conveyed between the horizontal registration movable plates by the third sheet conveying means, the rear end of the preceding paper passes through the exit of the horizontal registration movable plate. Until the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the conveyance of the first paper conveyance means is performed so that the succeeding paper is stopped before the entrance of the horizontal registration movable plate. It is characterized by comprising control means for controlling.

Further, when a preceding sheet having a different sheet width is being conveyed between the horizontal registration movable plates by the third sheet conveying means, the trailing end of the preceding paper passes through the exit of the horizontal registration movable plate. Until the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the conveyance of the first paper conveyance means is performed so that the succeeding paper is stopped before the entrance of the horizontal registration movable plate. It is characterized by comprising control means for controlling.

In the case where a preceding sheet having a different sheet size is being conveyed between the horizontal registration movable plates by the third sheet conveying means, the trailing end of the preceding paper passes through the exit of the horizontal registration movable plate. After the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the control for controlling the conveyance of the first paper conveyance means so that the leading end of the succeeding paper enters the entrance of the horizontal registration movable plate. It is characterized by comprising means.

In the case where a preceding sheet having a different sheet width is being conveyed between the horizontal registration movable plates by the third sheet conveying means, the trailing end of the preceding paper passes through the exit of the horizontal registration movable plate. After the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the control for controlling the conveyance of the first paper conveyance means so that the leading end of the succeeding paper enters the entrance of the horizontal registration movable plate. It is characterized by comprising means.

With this configuration, even when the preceding sheet is being conveyed at a low speed on both sides or being re-fed during double-sided continuous printing, the succeeding sheet can be speeded up by independent sheet conveying means. Therefore, a decrease in printing speed can be prevented.

For example, when the preceding sheet is being conveyed by the third sheet conveying means, the succeeding sheet can be conveyed faster or slower by the first sheet conveying means driven independently of the third sheet conveying means. On the other hand, when the succeeding sheet is being conveyed by the third sheet conveying means, the preceding sheet can be conveyed faster or slower by the second sheet conveying means driven independently of the third sheet conveying means. Further, when the preceding sheet is being conveyed by the second sheet conveying means, the succeeding sheet can be conveyed faster or slower by the first sheet conveying means driven independently of the second sheet conveying means. Can be transported at independent transport speeds according to the transport status of the paper.

The means for correcting the position in the main scanning direction of the paper using the movable lateral registration plate includes a moving means and a fine paper position adjusting means for performing two-stage movement between the horizontal registration adjustment position and the fine adjustment position. By performing the correction, the position of the sheet in the main scanning direction is corrected, so that more precise correction can be performed.

Further, since there is provided a paper transport speed control means for controlling the transport speed of the first to third paper transport means based on the paper length or the paper size, the transport control of each paper can be performed more precisely. it can.

Here, the paper length refers to the length of the paper in a direction parallel to the paper transport direction at a certain point when the paper is being transported in the apparatus. What is paper size?
For example, it refers to the size of the entire paper such as A4 or B5 (however, the paper size is not limited to a standardized paper size).

Further, since the start timing of the correcting operation of the position in the main scanning direction of the sheet by the correcting means is changed based on the sheet width of the sheet to be conveyed, even if the sheet width of the preceding sheet differs from that of the succeeding sheet. For example, it is possible to prevent the paper from being broken, jammed, or skewed by the horizontal resist movable plate. Here, the sheet width refers to the length of the sheet in a direction perpendicular to the sheet conveying direction at a certain point when the sheet is being conveyed in the apparatus.

In the case of continuous double-sided printing in which the paper size (paper width) is different between the preceding paper and the succeeding paper, the rear end of the preceding paper passes through the exit of the horizontal registration movable plate and the adjustment position movement of the horizontal registration movable plate is completed. Up to this point, the conveyance can be controlled by independent conveyance means so that the succeeding paper is stopped just before the entrance of the horizontal registration movable plate. However, the succeeding paper can enter the horizontal registration movable plate after the completion of the movement of the adjustment position, and the main scanning direction can be corrected to prevent skew and jam. Further, the succeeding paper can be conveyed at a high speed by an independent conveying means to a position not affected by the third conveying means, which leads to an improvement in printing speed.

Further, after the trailing edge of the preceding paper having a different paper size (paper width) has passed through the exit of the horizontal registration movable plate and the adjustment position of the horizontal registration movable plate has been moved, the leading end of the succeeding paper is moved to the entrance of the horizontal registration movable plate. For example, the first sheet conveying means is stopped by the first sheet conveying means having independent driving, or the sheet conveying speed is slowed by the first sheet conveying means to control the first sheet conveying. The waste of paper transport time from the means to the third paper transport means is eliminated, leading to a higher printing speed.

[0026]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

In the following drawings, the same reference numerals are given to members described in the drawings used in the description of the above-described prior art and members similar to the members described in the drawings described above.

(First Embodiment) A first embodiment of a two-sided image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing an electrical configuration of a double-sided image forming apparatus to which the present invention is applied. In FIG. 1, a microcomputer (hereinafter, referred to as a CPU) 201 is mounted on the double-sided image forming apparatus, and is connected to a video controller 202 via a serial communication line and several signal lines.

Reference numerals 205 to 211 denote sensor input circuits, the outputs of which are input to the CPU 201. A paper feed sensor signal (hereinafter, referred to as FEEDS) is input from the paper feed sensor 4 via the sensor circuit 205, and a pre-registration sensor signal (hereinafter, referred to as REGS) is input from the pre-registration sensor 7 via the sensor circuit 206. Then, a fixing discharge sensor signal (hereinafter, referred to as FPOUTS) is input from the fixing discharge sensor 12 via the sensor input circuit 207.

A reverse sensor signal (hereinafter, referred to as SWBKS) is input from the reverse sensor 16 via the sensor input circuit 208, and a double-sided sensor signal (hereinafter, referred to as DUPS) is transmitted from the double-sided sensor 20 via the sensor input circuit 209. ) Is input, and a D-cut roller home position sensor signal (hereinafter referred to as DRHP) is sent from the D-cut roller home position sensor 203 via the sensor input circuit 210.
S) is input.

Further, the horizontal registration movable plate / home position sensor signal (hereinafter referred to as H) from the horizontal registration movable plate / home position sensor 204 via the sensor input circuit 211.
RHPS).

Reference numerals 212 to 221 denote drive circuits for drive components, which are driven by drive signals output from the CPU 201. In response to a main motor drive signal (hereinafter referred to as an MMD), the main motor 2
22 and a feed motor drive signal (hereinafter referred to as FEEDM
D) through the drive circuit 213 to drive the paper feed motor 223.

In addition, a reverse motor drive signal (hereinafter referred to as SWB
KMD) and a rotation direction instruction signal (hereinafter SB)
The drive circuit 214 drives the reversing motor 224 via a drive circuit 214 by a drive circuit 214 (hereinafter referred to as DIRD) and a drive signal for a lateral registration movable plate motor (hereinafter referred to as HREGMD) and a rotation direction instruction signal (hereinafter referred to as HRDIRD).
The lateral registration motor 225 is driven via the reference numeral 15.

A double-sided conveyance motor drive signal (hereinafter referred to as D
UPMD) drives the double-sided conveyance motor 226 via the drive circuit 216, and drives the refeed motor 227 via the drive circuit 217 by the refeed motor drive signal (hereinafter referred to as RFDMD) to feed paper. The sheet feeding / conveying clutch 228 is driven via a driving circuit 218 by a conveying clutch drive signal (hereinafter referred to as FEEDCLD).

A driving circuit 219 is operated in response to a registration roller clutch driving signal (hereinafter referred to as “REGCLD”).
, A double-sided flapper solenoid 230 is driven via a drive circuit 220 by a double-sided flapper solenoid drive signal (hereinafter, referred to as DUPSLD), and a reverse roller pressure release solenoid drive signal (hereinafter, SFSLD and Drive circuit 2
The reversing roller pressure releasing solenoid 231 is driven via 21.

Therefore, the CPU 201, the driving circuit 21
4, 216, 217, the reversing motor 224, the two-sided conveying motor 226, and the re-feeding motor 227 constitute the sheet conveying speed control means of the present invention. Further, the CPU 201, the drive circuit 214, and the reversing motor 224 constitute a control unit of the present invention.

FIG. 2 is a sectional view showing the configuration of the double-sided image forming apparatus. In the image forming apparatus 1, the paper feed roller 3 is rotated by the paper feed motor 223 from the paper feed cassette 2 to feed the paper.

The paper size is detected by a paper size detection switch (not shown) in the paper feed cassette 2. Alternatively, the paper size is recognized by receiving the paper size by serial communication by the video controller 202 without the paper size detecting means.

The fed paper is detected by the paper feed sensor 4 and conveyed by rotating the paper feed conveyance roller 5 and the pre-registration roller 6 by the main motor 222 and the paper feed conveyance clutch 228 for transmitting the drive. You.

Then, the sheet is stopped a predetermined time after the leading edge of the sheet is detected by the pre-registration sensor 7. At this time,
A synchronization signal (hereinafter referred to as VSY)
When the input is input, the registration roller clutch 229 is driven to rotate the registration roller 8, and image print data is transmitted from the video controller 202.

The developed image is transferred to the photosensitive drum 9, fixed on the fixing pressure roller 10, and conveyed by the fixing discharge roller 11. Therefore, the photosensitive drum 9, the fixing pressure roller 10, and the fixing discharge roller 11 correspond to the image forming unit of the present invention.

When the leading edge of the sheet is detected by the fixing sheet ejection sensor 12 (state A), the double-sided flapper solenoid 230 is driven to guide the sheet to the double-side reversing unit. At the time (state B) when the leading edge of the sheet is detected by the reversing sensor 16,
Is driven in the pull-in direction at a low speed (same as the speed of the main motor 222) to rotate the reversing motor 17 as the first sheet conveying means of the present invention.

When a predetermined amount based on the sheet length is conveyed until the trailing edge of the sheet passes through the fixing sheet ejection sensor 12 (state C).
Thus, the paper is completely in the double-sided reversal section. At this time, the speed of the reversing roller 224 is increased.

Therefore, the double-sided flapper 13, the reversing roller 17, and the paper transport path in the states B, C and D correspond to the paper reversing mechanism of the present invention.

At the same time, in the case of a sheet having the same sheet size as the preceding sheet and a small sheet width, the horizontal registration movable plate motor 225
To move the horizontal registration movable plate 22 from the home position (outermost position) to the horizontal registration adjustment position (for example, a position wider by 8 mm than the sheet width).

When the trailing edge of the sheet has passed through the reversing sensor 16 and has been conveyed by a predetermined amount (state D), the reversing motor 224 is stopped, and the sheet reversal is completed. At this time, in the case of a sheet having the same sheet size as the preceding sheet and a large sheet width, the horizontal registration movable plate motor 225 is driven to start moving the horizontal registration movable plate 22 from the home position to the horizontal registration adjustment position.

When the paper size is different from that of the preceding sheet, at the time when the trailing edge of the preceding sheet passes through the exit of the horizontal registration movable plate 22 (state I), the movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is started. Until the adjustment movement is completed, the sheet is kept on standby with the reversing motor 224 stopped.

After the sheet reversal is completed, the reversing motor 224 is driven at a high speed in the double-sided conveying direction (toward the D-cut roller 18) to convey the sheet on both sides. The sheet is transported to the entrance of the horizontal registration movable plate (state E), and is transported between the horizontal registration movable plates.

When the leading edge of the sheet has reached the position just before the D-cut roller 18 (state F), the reversing motor 224 is switched to low-speed driving, and the two-sided conveying motor 226 is driven to serve as the third sheet conveying means of the present invention. D-cut roller 18 and double-sided conveying roller 1 as a third sheet conveying means of the present invention
9 is rotated at a low speed. After the leading edge of the sheet has passed through the D-cut roller 18, the D-cut roller / home position sensor 203 is monitored, and the double-sided conveyance is performed so that the sheet is at a home position (a position where the cut sheet of the D-cut roller does not affect the sheet). The driving of the motor 226 is stopped, and D
The rotation of the cut roller 18 and the duplex conveying roller 19 is stopped (state G).

The horizontal registration movable plate 22 that has been further conveyed by a predetermined amount (state H) by the rotation of the reversing roller 17 as it is and has been moved to the paper adjustment position is driven by the horizontal registration movable plate motor 225 to be finely moved. The skew of the position in the main scanning direction of the paper (the direction perpendicular to the paper conveyance direction (the paper width direction)) is corrected by adjusting (being sandwiched by a small amount smaller than the paper width).

At the start of the fine adjustment of the paper position, the reverse roller pressure release solenoid 231 is driven to drive the reverse roller 1 so that the paper can be easily corrected for movement in the main scanning direction.
Release the trailing edge of the paper biting at 7.

After fine adjustment of the sheet position, the two-sided conveyance motor 226
Is driven at a low speed, and the D-cut roller 18 and the double-sided roller 19
To stop the driving of the reversing roller pressure releasing solenoid 231 and continue the conveyance.

When the leading edge of the sheet is detected by the two-sided sensor 20 (state J), the movement of the horizontal registration movable plate 22 in the fine adjustment position to the home position by driving the horizontal registration movable plate motor 225 is started. Let it. When the trailing edge of the sheet passes through the reversing roller 17, the reversing motor 224 is stopped.

Therefore, the horizontal registration movable plate motor 22
Reference numeral 5 denotes the moving means of the present invention, the driving circuit 215 and the CPU 201 for controlling the driving circuit 215 constitute the paper position adjusting control means of the present invention. Further, the CPU 201 also serves as a timing control unit of the present invention.

Further, when the sheet comes to the position just before the re-feed roller 21, the re-feed motor 227 is driven at a low speed to rotate the re-feed roller 21 as the second sheet conveying means of the present invention. Then, when the leading edge of the sheet reaches a point before the confluence with the conveyance path from the sheet feeding cassette 2 (state L), the driving of the two-sided conveyance motor 226 and the re-feeding motor 227 is stopped, and the two-sided conveyance is completed. .

Therefore, the re-feed roller 21 and the state L
The paper transport path in the above corresponds to the paper re-feeding mechanism of the present invention.

In this state, the apparatus stands by until a print command for the second side specified by the video controller 202 is received. Along with the print command for the second surface, the duplex motor 226 and the re-feed motor 227 are driven at a low speed, and the main motor 222 and the paper feed clutch 228 are driven to rotate the pre-registration roller 6 to rotate the paper. Start re-feeding conveyance. Also, when the trailing edge of the paper has passed through the two-sided conveying roller 19,
The double-sided conveyance motor 226 is stopped.

After a predetermined time from the detection of the leading edge of the sheet by the pre-registration sensor 7, the driving of the feeding and conveying clutch 228 is stopped, and the two-sided conveying motor 226 and the re-feeding motor 2 are stopped.
Then, the driving of the sheet feeding device 27 is stopped, the re-feeding conveyance is completed, and the sheet is stopped. When VSYNC is input from the video controller 202, a registration roller clutch 229 for rotating the registration roller 8 is driven, and image print data is transmitted from the video controller 202.
On the sheet, a second image developed on the photosensitive drum 9 is transferred, fixed by a fixing pressure roller 10, and conveyed by a fixing discharge roller 11.

Then, the double-sided flapper solenoid 230 is not driven, and the paper is guided by the double-sided flapper 13 to the paper discharge roller 14 and discharged to the paper discharge tray 15.

FIG. 3 is a perspective view of the horizontal registration movable plate in the double-sided image forming apparatus. The horizontal resist movable plate is composed of two parts, between which a sheet is conveyed, and the position in the main scanning direction is corrected by sandwiching the sheet from both sides.

FIGS. 4 and 5 are flowcharts showing the processing procedure of only the reverse pull-in, double-sided conveyance, and re-feeding conveyance related to both sides of the processing contents of the CPU in the double-sided image forming apparatus of this embodiment.

Check FPOUTS, and wait until the fixing sheet ejection sensor 12 detects the leading edge of the sheet (S30).
1). When the leading edge of the sheet is detected, the DUPSLD is driven to drive the double-sided flapper (S302). The paper size detected by a paper size detection switch (not shown) in the paper cassette 2 or the paper size received by serial communication from the video controller 202 is
The data is stored in the RAM area of the CPU (S303).

Check SWBKS and check the reverse sensor 1
6 waits until the leading edge of the sheet is detected (S304). When the leading edge of the sheet is detected, the reversing motor 224 is driven to rotate forward on the reversing pull-in side at the same low speed as the speed of the main motor 222 (S305), and the driving of the DUPSLD is stopped to stop the driving of the double-sided flapper (S306).

The FPOUTS is checked again and the process waits until the trailing edge of the sheet is detected by the fixing sheet ejection sensor 12 (S
307). When the trailing edge of the sheet is detected, the reversing motor 224 is driven at a high speed (S308).

It is checked whether there is a sheet having a different sheet size during the preceding two-sided conveyance (9S309), and it is checked whether the sheet width is small (S310). If there is no preceding sheet having a different sheet size and the sheet width is small, The movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is started (S3).
11).

The SWBKS is checked again, and the process waits until the reverse sensor 16 detects the trailing edge of the sheet (S31).
2). When the trailing edge of the sheet is detected, a predetermined moving amount until the trailing edge of the sheet passes the reverse branch point is set (S313), and the completion of the moving of the predetermined amount is waited (S314). When the move is complete,
The driving of the reverse motor 224 is stopped (S315), and the conveyance of the sheet is stopped.

Here, the result already checked in S309 (whether there is a sheet of a different sheet size during the preceding double-sided conveyance) is checked (S316). If there is no preceding paper having a different paper size, it is checked whether the paper width is large (S317).
The movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is started (S318).

If there is a preceding sheet of a different paper size during the double-sided conveyance, it is checked whether or not there is a preceding sheet in the horizontal registration movable plate 22, and the preceding paper is transferred to the horizontal registration movable plate 22.
(S319).

When the preceding sheet passes through the horizontal registration movable plate 22, the movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is started (S320). And the horizontal resist movable plate 2
The process waits until 2 moves to the horizontal registration adjustment position (S321).

The reversing motor 224 is driven at a high speed in the reverse rotation direction on the double-sided conveyance side (S322), and the process shifts to double-sided conveyance. When the conveyance to the double-sided conveyance side is started, a predetermined movement amount is set until the leading end of the sheet reaches the position before the D-cut roller 18 (S32).
3) Wait for completion of the predetermined amount of movement (S324).

After the movement is completed, the double-sided conveyance motor 226 is driven at a low speed (S325), and the reversing motor 224 is lowered at a low speed in the reverse rotation direction (S326). And the leading edge of the paper is D
A predetermined amount of movement before passing through the cut roller 18 is set (S327), and the completion of the movement of the predetermined amount is waited for (S32).
8).

Check the DRHPS and wait for the D-cut roller home position sensor to detect the home position (S329). When the D-cut roller reaches the home position, the drive of the duplex conveying motor 226 is stopped, and the D-cut roller is stopped at the home position (S330). Then, a predetermined moving amount until the leading end of the sheet reaches the exit of the horizontal registration movable plate is set (S33).
1) Wait for the completion of the predetermined amount of movement (S332).

By driving the SFSLD, the reverse motor pressure releasing solenoid 231 is driven to make the trailing end of the sheet on the reverse roller 17 free (S333). Horizontal resist movable plate 22
Then, fine adjustment of the lateral resist is started (S334).

Wait until the horizontal registration fine adjustment is completed (S
335). When the fine adjustment of the lateral registration is completed, the duplex conveying motor 226 is driven at a low speed (S336), the driving of the SFSLD is stopped, the driving of the reversing motor pressure release solenoid 231 is stopped, and the sheet is restrained by the reversing roller 17 (S33).
7) Transport is restarted.

The DUPS is checked, and the duplex sensor 20 is checked.
Wait for the sheet to detect the leading edge of the sheet (S338). When the leading edge of the sheet is detected, the movement of returning the horizontal registration movable plate 22 from the horizontal registration fine adjustment position to the home position is started (S339).

Further, since the timing at which the trailing edge of the sheet passes through the reversing roller 17 differs depending on the length of the sheet, if the trailing edge of the sheet passes through the reversing roller 17 and there is no succeeding sheet, the reversing motor 22
Another monitoring process for performing the process of stopping the driving of No. 4 is started (S340).

A predetermined movement amount until the leading end of the sheet reaches the position before the re-feed roller 21 is set (S341), and the completion of the movement of the predetermined amount is waited (S342). When the movement is completed, the refeed motor 227 is driven at a low speed (S343).

Then, a predetermined amount of movement is set until the leading edge of the sheet reaches a point before the merging point where the sheet merges with the conveyance path from the sheet feeding cassette 2 (S344), and the completion of the predetermined amount of movement is waited for (S344).
345).

When the movement is completed, the two-sided conveyance motor 226
Is stopped (S346), the driving of the re-feed motor S227 is stopped (S347), the double-sided conveyance is terminated, and the sheet is stopped at the re-feed standby position.

It waits for a print instruction (refeed instruction) for the second surface from the video controller 202 (S34).
8).

When a refeed instruction is received, the double-sided conveying motor 2
26 is driven at low speed (S349), the re-feed motor 227 is driven at low speed (S350), and re-feed conveyance is started. Further, since the timing at which the trailing edge of the sheet passes through the two-sided roller 19 differs depending on the length of the sheet, another monitoring operation for stopping the driving of the two-sided motor 226 if the trailing edge of the sheet passes through the two-sided roller 19 and there is no subsequent sheet. The processing is started (S35)
1).

Then, the main motor 222 is driven (S
352), and drives the sheet feeding clutch 228 (S35).
3) The pre-registration roller 7 is rotated.

After checking REGS, the process waits until the leading edge of the sheet is detected by the pre-registration sensor 7 (S354). When the leading edge of the sheet is detected, the leading edge of the sheet is abutted against the registration roller 8 to set a predetermined movement amount until a predetermined loop is created (S355), and the movement of the predetermined amount is waited for (S3).
56).

When the movement is completed, if there is no succeeding sheet, the driving of the two-sided conveying motor 226 is stopped (S357), the driving of the re-feeding motor 227 is stopped (S358), the driving of the sheet feeding / conveying clutch is stopped, and the pre-registration is stopped. The rotation of the roller is stopped (S359). With this, the re-feeding conveyance is completed, and the entire double-sided conveyance control is completed.

Thereafter, upon receiving the VSYNC from the video controller 202, the registration clutch 229 is driven to rotate the registration roller 8, and the sheet feeding / conveying clutch 22 is rotated.
8 to drive the pre-registration roller 6 to start printing on the second surface.

In this embodiment, the reversing motor 224 and the two-sided conveying motor 226 can be driven completely independently. Conventionally, the same motor is used, and two of the D-cut roller 18 and the double-sided roller 19 are configured so that the drive can be separated from the reversing roller by a clutch. During the transportation of the sheet, the reversing roller 17 of the succeeding paper must be rotated, the succeeding paper cannot be stopped, and the transport speed of the preceding paper and the succeeding paper cannot be changed.

For this reason, when the preceding paper is being conveyed on both sides, the speed cannot be increased by the reverse pull-in conveyance of the succeeding paper. However, in the present invention, since the independent driving system is used, whether the preceding paper is being conveyed on both sides is determined. Regardless of whether or not it is possible, the succeeding paper can be pulled in at high speed (corresponding to S308), and the printing speed can be improved.

Furthermore, high-speed conveyance (S32) is also performed during double-sided conveyance in the transition section from the reversing motor 224 to the double-sided motor 226.
2 to S326), and the printing speed can be improved.

Similarly, conventionally, during the double-sided conveyance of the preceding paper, the succeeding paper cannot be stopped.
In two-sided continuous printing with different paper sizes with greatly different paper widths, if the trailing edge of the preceding paper starts to move to the horizontal registration adjustment position after the trailing edge of the horizontal registration movable plate has passed through the exit, the same speed as the preceding paper When the succeeding paper conveyed in the above enters the entrance of the horizontal registration movable plate, since the movement to the horizontal registration adjustment position has not been completed, this causes a skew or a jam. Conversely, if the movement to the horizontal registration adjustment position is completed by the time the succeeding paper enters the entrance of the horizontal registration movable plate, the trailing edge of the preceding paper will not pass through the exit of the horizontal registration movable plate. To move to the horizontal registration adjustment position, the rear end of the preceding paper is pinched too much, causing scratches and jams.

According to the present embodiment, the preceding sheet and the succeeding sheet can be independently conveyed and the succeeding sheet can be stopped, so that the preceding sheet passes through the exit of the lateral resist movable plate 22 and moves to the horizontal resist movable plate. Since the transport of the succeeding paper can be stopped until the movement is completed after the movement to the horizontal registration adjustment position of No. 22 (corresponding to S319 to S321), when the preceding paper enters the entrance of the horizontal registration movable plate, the horizontal registration is performed. The adjustment position allows stable printing without skewing or jamming even in continuous printing on both sides of paper having greatly different paper widths.

(Second Embodiment) Next, a second embodiment to which the present invention can be applied will be described with reference to FIGS. The block diagram (FIG. 1), the sectional configuration diagram (FIG. 2), and the perspective view (FIG. 3) of the horizontal resist movable plate of the electrical configuration of the double-sided image forming apparatus are the same as those of the above-described first embodiment. Description is omitted.

FIGS. 6 and 7 are flow charts showing the processing procedure of only the reverse pull-in, double-sided conveyance, and re-feeding conveyance of both sides of the processing contents of the CPU in the double-sided image forming apparatus. S301 to S320, S32
Steps 2 to S335 and S337 to S359 are the same as those in FIGS. 4 and 5 of the first embodiment, and therefore, different portions (S401 to S406) from the first embodiment will be described.

First, the parts related to S401 and S402 will be described. It is checked whether or not there is a preceding sheet in the horizontal registration movable plate 22, and the process waits until the trailing edge of the preceding sheet comes off the exit of the horizontal registration movable plate 22 (S319). When it is removed, the movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is started.

Then, the time obtained by subtracting (the time during which the succeeding sheet moves from the current stop position to the entrance 22 of the horizontal registration movable plate by high-speed transport) is subtracted from (the time required for the horizontal registration movable plate 22 to move to the horizontal registration adjustment position). Is the waiting time (S401). Wait for the waiting time to elapse (S40)
2). Then, the reversing motor 224 is driven at a high speed in the reverse rotation direction on the double-sided conveyance side (S322), and the process shifts to double-sided conveyance.

Next, parts related to S403 and S404 will be described. When the conveyance to the two-sided conveyance side is started, a predetermined movement amount until the leading end of the sheet reaches the position before the D-cut roller 18 is set (S323), and the completion of the movement of the predetermined amount is waited (S323).
324).

After the movement is completed, the trailing edge of the preceding paper is
It is checked whether 9 has been omitted (S403). If not, the double-sided conveyance motor 226 is driven at a low speed (S325), and the reversing motor 224 is dropped at a low speed in the reverse rotation direction (S326). If detached, the double-sided conveyance motor 226 is driven at high speed (S404), and the reverse motor 224 is driven.
Is set to the reverse direction high speed as it is.

Next, step S405 will be described. After the fine adjustment of the horizontal registration movable plate 22 is completed (S335), the speed of the double-sided conveyance motor 226 is returned to the original speed drive before stopping at S330 (S336).

Next, step S406 will be described. A predetermined movement amount until the leading edge of the sheet reaches the position before the re-feed roller 21 is set (S341), and the completion of the movement by the predetermined amount is waited (S34).
2). When the movement is completed, the double-sided conveyance motor 226 is set to low speed drive (S406), and the re-feed motor 227 is driven at low speed (S343).

When the paper sizes are different, in the above-described first embodiment, the conveyance of the succeeding paper is restarted after the movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is completed. On the other hand, in the second embodiment, S401 to S401
By performing the control of 402, the waiting time is determined by comparing the moving time of the horizontal registration movable plate 22 to the horizontal registration adjustment position and the transport time of the succeeding paper to the entrance of the horizontal registration movable plate. When the movable plate 22 completes the movement to the horizontal registration adjustment position, the succeeding sheet has just been conveyed to the entrance of the horizontal registration movable plate 22.

Therefore, the position of the succeeding sheet when the movement of the horizontal registration movable plate 22 to the horizontal registration adjustment position is in the state D in the first embodiment, but is in the state E in the second embodiment. Therefore, the printing speed is improved by the amount of conveyance from the state D to the state E.

In this embodiment, the double-sided conveyance motor 226 for performing double-sided conveyance and the re-feeding motor 2
In the second embodiment, if the trailing edge of the preceding sheet has passed through the double-sided roller 19, the second sheet feeding roller 21 is controlled by the control of steps S403 to S406. The two-sided conveyance up to this side is all conveyed at high speed. This further improves the printing speed.

Here, the first embodiment and the second embodiment
In the embodiment, as a simple processing example, it is checked that the sheet size of the preceding sheet and the sheet size of the succeeding sheet during the duplex conveyance are different (S309, S316).
Even if the paper sizes are different, if the paper width is the same (for example, A3 portrait and A4 landscape), there is no need to perform a separate process, so it may be checked that the paper widths are different.

Also, if the transport speed is low (the main motor 22
Although the present embodiment has a two-stage embodiment having the same speed as the second speed) and a high-speed embodiment, finer control may be performed in more stages. Further, the double-sided image forming apparatus is an integrated type of one side and both sides, and one CPU
However, both sides inside the dotted line in FIG.
The configuration of a two-sided image forming apparatus in which a PU is mounted and communication is performed between the printing apparatus main body and the two-sided unit by communication may be employed.

[0104]

As described above, according to the present invention,
In the case of continuous printing on both sides, even when the preceding paper is being conveyed on both sides at low speed or during re-feeding, the succeeding paper can be speeded up by independent paper conveying means, so that the printing speed can be improved.

In the case of continuous double-sided printing in which the paper size (paper width) differs between the preceding paper and the succeeding paper, the trailing edge of the preceding paper passes through the exit of the horizontal registration movable plate and moves the horizontal registration adjustment position of the horizontal registration movable plate. After the completion, the leading edge of the succeeding paper can be controlled to be conveyed to the entrance of the horizontal registration movable plate, so that the main scanning direction can be corrected even if the paper width greatly differs and the adjustment position movement time of the horizontal registration movable plate increases. It can prevent skewing and jam. Further, in continuous printing with different paper sizes (paper widths), even if waiting until the movement of the adjustment position of the horizontal registration movable plate is completed, the succeeding paper is then moved by independent transport means to a position not affected by the transport means of the preceding paper. Since the paper can be conveyed at a high speed, a decrease in the printing speed can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an electrical configuration of a first embodiment of a two-sided image forming apparatus according to the present invention.

FIG. 2 is a sectional configuration diagram of a first embodiment of a two-sided image forming apparatus according to the present invention.

FIG. 3 is a perspective view showing an overview of a horizontal registration movable plate in the first embodiment of the duplex image forming apparatus according to the present invention.

FIG. 4 is a flowchart illustrating a duplex processing procedure of a CPU in the first embodiment of the duplex image forming apparatus according to the present invention.

FIG. 5 is a flowchart illustrating a double-side processing procedure of a CPU in the first embodiment of the double-sided image forming apparatus according to the present invention.

FIG. 6 is a flowchart illustrating a double-sided processing procedure of a CPU in a second embodiment of the double-sided image forming apparatus according to the present invention.

FIG. 7 is a flowchart illustrating a double-sided processing procedure of a CPU in a double-sided image forming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 double-sided image forming apparatus 2 paper feed cassette 3 paper feed roller 4 paper feed sensor 5 paper feed transport roller 6 pre-registration roller 7 pre-registration sensor 8 registration roller 9 photosensitive drum 10 fixing pressure roller 11 fixing discharge roller 12 fixing discharge Sensor 13 Double-sided flapper 14 Discharge roller 15 Discharge tray 16 Reverse sensor 17 Reverse roller 18 D-cut roller 19 Double-side transport roller 20 Double-side sensor 21 Re-feed roller 22 Lateral registration movable plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/00 106 G03G 15/00 106 3F102 21/14 21/00 372 F term (Reference) 2C061 AR03 HH01 HJ03 HL01 HN17 2H027 DC10 DE07 ED16 EE03 EE06 FA11 2H028 BA06 BA09 BA16 BB04 3F049 DA12 EA22 EA24 LA03 LB03 3F100 AA02 BA05 CA11 DA04 EA04 EA06 EA18 3F102 AA07 AB01 BA02 BB04 EA14 FA03

Claims (9)

[Claims] 1. A double-sided image forming apparatus comprising: a sheet reversing mechanism for drawing a sheet into a reversing conveyance path and reversing the sheet; and a re-feeding mechanism for joining the reversed sheet to an image forming unit. Correction means for correcting the position in the scanning direction, first paper conveyance means for conveying the paper by the paper reversing mechanism, and second conveyance means for conveying the paper in order to join the paper from the re-feeding mechanism to the image forming section. A second sheet conveying means, and a third sheet conveying means for conveying a sheet from the sheet reversing mechanism to the re-feeding mechanism via the correcting means, wherein the first sheet conveying means, the second sheet conveying means, Paper transport means and third
Wherein the paper transport means are independently transported and driven. 2. The moving device according to claim 1, wherein the correcting unit is configured to move the horizontal registration movable plate in contact with an end portion of the paper in the main scanning direction; 2. The double-sided image forming apparatus according to claim 1, further comprising a sheet position adjustment control unit that controls the moving unit so as to perform the correction operation. 3. A method according to claim 1, wherein the first sheet conveying means, the second sheet conveying means, and the third sheet conveying means are arranged based on a sheet size of the sheet to be conveyed.
The double-sided image forming apparatus according to claim 1, further comprising a sheet conveyance speed control unit that controls a conveyance speed of the sheet conveyance unit. 4. A method according to claim 1, wherein said first sheet conveying means, said second sheet conveying means, and said third sheet conveying means are arranged based on a sheet length of said sheet to be conveyed.
The double-sided image forming apparatus according to claim 1, further comprising a sheet conveyance speed control unit that controls a conveyance speed of the sheet conveyance unit. 5. The apparatus according to claim 1, wherein a start timing of the correction operation of the position in the main scanning direction of the sheet by the correction unit is changed based on a sheet width of the sheet to be conveyed.
The two-sided image forming apparatus according to any one of the above. 6. When a preceding sheet having a different sheet size is being conveyed between the horizontal registration movable plates by the third sheet conveyance means, a rear end of the preceding paper passes through an exit of the horizontal registration movable plate. Until the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the conveyance of the first paper conveyance means is performed so that the succeeding paper is stopped before the entrance of the horizontal registration movable plate. The double-sided image forming apparatus according to any one of claims 2 to 5, further comprising control means for controlling. 7. When a preceding sheet having a different sheet width is being conveyed between the horizontal registration movable plates by the third sheet conveyance means, a trailing end of the preceding paper passes through an exit of the horizontal registration movable plate. Until the movement for adjusting the position of the horizontal registration movable plate in the main scanning direction of the paper is completed, the conveyance of the first paper conveyance means is performed so that the succeeding paper is stopped before the entrance of the horizontal registration movable plate. The double-sided image forming apparatus according to any one of claims 2 to 5, further comprising control means for controlling. 8. When a preceding sheet of a different sheet size is being conveyed between the horizontal registration movable plates by the third sheet conveyance means, the trailing end of the preceding paper passes through the exit of the horizontal registration movable plate. After the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the control for controlling the conveyance of the first paper conveyance means so that the leading end of the succeeding paper enters the entrance of the horizontal registration movable plate. The double-sided image forming apparatus according to any one of claims 2 to 5, further comprising a unit. 9. When a preceding sheet having a different sheet width is being conveyed between the horizontal registration movable plates by the third sheet conveyance means, a trailing end of the preceding paper passes through an exit of the horizontal registration movable plate. After the movement of the horizontal registration movable plate for adjusting the position in the main scanning direction of the paper is completed, the control for controlling the conveyance of the first paper conveyance means so that the leading end of the succeeding paper enters the entrance of the horizontal registration movable plate. The double-sided image forming apparatus according to any one of claims 2 to 5, further comprising a unit.