JP2001039585A - Picture image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely position a sheet and a picture image without lowering throughput of printing. SOLUTION: Blurring of time when a sheet 29 is carried to a first resist roller 15 and a second resist roller 13 is absorbed by a change of stopping time of the sheet 29 respectively at each of the first resist roller 15 and second resist roller 13 by making carriage starting time of the sheet 29 from the first resist roller 15 and the second resist roller 13 a standard of time after an electrostatic latent image is written on a photosensitive member belt 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a printer, a facsimile, a copying machine, and the like, in which a correction of a paper conveyance delay and a correction of a skew of a paper are performed a plurality of times during the conveyance of the paper, and The present invention relates to an image forming apparatus that accurately performs alignment with an image.

[0002]

2. Description of the Related Art Next, a conventional image forming apparatus of this type will be described with reference to the drawings.

FIG. 4 is a schematic configuration diagram showing a conventional image forming apparatus 100.

Referring to FIG. 4, an image forming apparatus 100
Is a photoreceptor belt 1 on which an image is written, a charger 11 for uniformly charging the surface of the photoreceptor belt 1, and a yellow laser unit for exposing the surface of the photoreceptor belt 1 to write an electrostatic latent image of each color. (Y-LD) 31, magenta laser unit (M-LD) 32, cyan laser unit (C-LD) 33, and black laser unit (KL)
D) a laser unit 3 comprising: a developing unit 41; a yellow developing unit 41 which develops the written electrostatic latent image of each color to form a toner image on the surface of the photoreceptor belt 1;
2, a developing device 4 including a cyan developing device 43 and a black developing device 44, a transfer roller 2 for transferring a developed image to a sheet 29, and an eraser 12 for removing charges remaining on the surface of the photoreceptor belt 1. And a hopper 28 for storing paper 29, a pick roller 18 for picking the paper 29 from the hopper 28, a first transport roller 17, a second transport roller 16, and a third transport roller 1 for transporting the picked paper 29.
A registration roller 113 for temporarily stopping the sheet 29 conveyed from the fourth conveyance roller 14 and correcting skew of the sheet 29 and correcting a conveyance delay;
Sheet sensors 21 and 19 provided near the printer 8 and the registration roller 113 to detect the presence or absence of a sheet 29, a photoreceptor belt motor 25 for rotating the photoreceptor belt 1, and a registration motor 22 for rotating the registration roller 113, respectively. ,
A feed motor 23 for rotating the third transport roller 115 and the fourth transport roller 14, a hopper motor 24 for rotating the pick roller 18, the first transport roller 17 and the second transport roller 16, a photoreceptor belt motor 25, The operation of the image forming apparatus 100 configured as described above, including the motor 22, the feed motor 23, the hopper motor 24, and the control unit 27 that controls the developing device 4, will be described with reference to the drawings.

FIG. 5 is a diagram showing the relationship between the position of the sheet 29 and the time during conveyance.

FIG. 6 is a diagram showing the relationship between the position of the sheet 29 and the time when a pick mistake of the sheet 29 occurs. Note that a solid line indicates when a pick error has occurred, and a two-dot chain line indicates a normal case when there is no pick error.

Referring to FIGS. 4, 5 and 6, when a print request is sent from information processing device 26 to control portion 27 of image forming apparatus 100, control portion 27 controls hopper motor 24 and feed motor 23. , The first transport roller 17,
The second transport roller 16 and the pick roller 18 are turned on, the paper 29 is picked from the hopper 28 and transported. When the paper sensor 20 is turned on, the third transport roller 115 and the fourth transport roller 14 are turned on, and the registration is performed. The sheet 29 is transported to the rollers 113.

By turning off the third conveying roller 115 and the fourth conveying roller 14 after a certain period of time after the paper sensor 19 is turned on, the conveyance of the paper 29 is stopped, and the yellow laser unit (Y-LD) 31 Is turned on to turn on the registration roller 113 at a timing at which the image drawn on the photoreceptor belt 1 is transferred to the paper 29 by the transfer roller 2 after a predetermined time from the start of writing the electrostatic latent image on the photoreceptor belt 1, The conveyance of the paper 29 is restarted.

However, the above-described image forming apparatus 100 has the following problems when a pick mistake occurs and the sheet conveyance is delayed.

Referring to FIG. 6, when a pick error occurs in the pick roller 18 and a second pick is performed, the transfer is temporarily stopped by the registration roller 113 and then the transfer is started again (t1 in FIG. 6). Then, the paper 29 has not yet reached the registration roller 113, and the transfer roller 2
The paper 29 is conveyed to the printer, so that the alignment between the paper 29 and the image is not correctly performed.

Further, the first sheet 29 having a pick error
The rear end and the front end of the next second sheet 29 interfere with each other and collide with each other, causing a jam phenomenon.

Therefore, in order to improve the above problem, the waiting time (stop time) of the paper 29 at the registration roller 113 is adjusted to absorb the fluctuation in the time from picking the paper 29 to hitting the registration roller 113. However, if the interval between picks of the paper 29 is the same, if the standby time is too long, the paper 29 may be jammed and jammed.

Further, by increasing the interval for transporting the paper 29, the standby time of the paper 29 at the registration roller 113 can be lengthened, but in this case, there is a disadvantage that the printing throughput is reduced.

[0014]

As described above, in the conventional image forming apparatus, when the conveyance of the paper is delayed, the alignment between the paper and the image is not performed correctly, and the rear end of the first paper and the next paper are not aligned. However, there is a problem that the leading edge of the second sheet interferes with the second sheet to cause a jam phenomenon.

SUMMARY OF THE INVENTION It is an object of the present invention to adjust the position of a sheet and an image without deteriorating the printing throughput by correcting the sheet conveyance delay and correcting the skew of the sheet a plurality of times during the sheet conveyance. To provide an image forming apparatus that can accurately perform the image formation.

[0016]

According to the present invention, there is provided an image forming apparatus comprising: a photoreceptor belt on which an image is written; a charger for uniformly charging the surface of the photoreceptor belt; A laser unit that writes electrostatic latent images of each color, a developing device that develops the written electrostatic latent images of each color to form a toner image on the surface of the photoreceptor belt, and a transfer that transfers the developed image to paper Rollers, an eraser for removing charges remaining on the photoreceptor belt surface, a hopper for storing paper, a pick roller for picking paper from the hopper, a transport roller for transporting the picked paper, and a transport roller from the transport roller. A registration roller for temporarily stopping the paper sheet and correcting skew of the paper sheet and correction of paper conveyance delay;
A paper sensor is provided near the pick roller and the registration roller to detect the presence or absence of paper, and a plurality of registration rollers are provided between the pick roller and the transfer roller.

Further, the image forming apparatus of the present invention comprises a photoreceptor belt on which an image is written, a charger for uniformly charging the surface of the photoreceptor belt, A laser unit for writing a latent image, a developing device for developing a written electrostatic latent image of each color to form a toner image on the surface of a photoreceptor belt, a transfer roller for transferring the developed image to paper, An eraser for removing charges remaining on the surface of the body belt, a hopper for storing paper, a pick roller for picking paper from the hopper, a first transport roller and a second transport roller for transporting the picked paper, and a first transport A first registration roller for temporarily stopping the sheet conveyed from the rollers and the second conveyance roller to correct the skew of the sheet and to correct a delay in the conveyance of the sheet, and resume the operation of the first registration roller A fourth transport roller for transporting the paper, a second registration roller for temporarily stopping the paper transported from the fourth transport roller and correcting the skew of the paper and the correction of the transport delay of the paper, a pick roller, and a pick roller. A paper sensor provided near each of the first registration roller and the second registration roller for detecting the presence or absence of a sheet, a photoconductor belt motor for rotating the photoconductor belt, a registration motor for rotating the second registration roller, and a fourth transporter A feed motor that rotates the roller and the first registration roller, a hopper motor that rotates the pick roller, the first conveyance roller, and the second conveyance roller, and a photoreceptor belt motor, a registration motor, a feed motor, a hopper motor, and a developing device are controlled. And a control unit that performs the control.

The first registration roller and the second registration roller are characterized in that they are arranged at an interval longer than the length of the sheet in the transport direction.

The pick roller and the first registration roller are
It is characterized by being arranged at an interval longer than the length of the sheet in the transport direction.

The first registration roller and the second registration roller are characterized in that the conveyance delay of the sheet is corrected by changing the stop time.

Each of the first registration roller and the second registration roller restarts the sheet conveyance after a predetermined time has elapsed from the start of image writing on the photosensitive belt.

The time from the start of writing an image on the photoreceptor belt by the laser unit to the start of picking of paper is from the time from the start of writing the image on the photoreceptor belt by the laser unit to transfer to the paper by the transfer roller. And a value obtained by subtracting the time required for conveying the paper from picking the paper to reaching the transfer roller.

The first transport roller, the second transport roller, the fourth transport roller, the pick roller, and the first registration roller each have a clutch.

The laser unit includes a yellow laser unit, a magenta laser unit, a cyan laser unit,
And a black laser unit.

The developing device comprises a yellow developing device, a magenta developing device, a cyan developing device, and a black developing device.

The paper sensor is an optical sensor.

[0027]

Next, an embodiment of an image forming apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic structural view showing an image forming apparatus 50 of the present invention.

The conventional image forming apparatus 10 shown in FIG.
Components that are the same as 0 are denoted by the same reference numerals.

Referring to FIG. 1, the image forming apparatus 50 includes:
A photosensitive belt 1 on which an image is written, and a photosensitive belt 1
Charger 11 for uniformly charging the surface of the photosensitive member, and photoreceptor belt 1
An eraser 12 for removing electric charges remaining on the surface, a yellow laser unit (Y-LD) 31, a magenta laser unit (M-LD) 32, and a cyan laser unit for exposing the surface of the photoreceptor belt 1 and exposing images of respective colors. (C
-LD) 33 and black laser unit (KL)
D) 34, a yellow developing unit 41, a magenta developing unit 42 for developing a written image of each color to form a toner image on the surface of the photosensitive belt 1;
A developing unit 4 including a cyan developing unit 43 and a black developing unit 44; a transfer roller 2 for transferring a developed image to a sheet 29; a hopper 28 in which the sheet 29 is stored; and picking the sheet 29 from the hopper 28 Pick roller 18
And the first transport roller 17 that transports the picked sheet 29
A first registration roller 15 for temporarily stopping the sheet 29 conveyed from the first conveyance roller 17 and the second conveyance roller 16 and correcting the skew of the sheet 29 and aligning the image; , First registration roller 15
And a second registration roller 13 for temporarily stopping the sheet 29 conveyed from the fourth conveyance roller 14 and correcting the skew of the sheet 29 and aligning the image. Optical sheet sensors 21, 20, and 19 provided near the pick roller 18, the first registration roller 15, and the second registration roller 13 to detect the presence or absence of a sheet 29, and a photosensitive member for rotating the photosensitive belt 1. Body motor 25, a registration motor 22 for rotating the second registration roller 13, and a feed motor 2 for rotating the fourth conveyance roller 14 and the first registration roller 15.
3, a hopper motor 24 for rotating the pick roller 18, the first transport roller 17 and the second transport roller 16, and a control for controlling the photoreceptor belt motor 25, the registration motor 22, the feed motor 23, the hopper motor 24, and the developing device 4. The first registration roller 15 and the second registration roller 13 are disposed at a distance interval longer than the length of the sheet 29 in the transport direction, and the pick roller 1
8 and the first registration roller 15 are arranged at a distance interval longer than the length of the sheet 29 in the transport direction.

The first transport roller 17, the second transport roller 16, the fourth transport roller 14, the pick roller 18, and the first registration roller 15 each have a clutch and can be independently controlled. It has become.

Next, the operation of the image forming apparatus 50 configured as described above will be described with reference to the drawings.

FIG. 2 is a diagram showing the relationship between the position of the sheet 29 and the time when the sheet 29 is conveyed by a solid line, and the relationship between the image position on the photosensitive belt 1 and the time by a dashed line.

Referring to FIGS. 1 and 2, when a print request is sent from the information processing device 26 to the control unit 27, the control unit 27 activates the laser units 3 of each color to activate the photosensitive belt 1 , The charger 11 and the eraser 1
2 is turned on. When the activation of the laser unit 3 is completed and the laser unit 3 is in a printable state, the information processing device 26
The image data of each color flows, and writing of an electrostatic latent image on the photosensitive belt 1 by the laser unit 3 is started. The electrostatic latent image written by the laser unit 3 is developed by each of the developing devices 4 and transferred to the transfer roller 2, and further transferred to the transported paper 29.

After a certain period of time from the start of writing the electrostatic latent image on the photosensitive belt 1 (after the start of writing the electrostatic latent image on the photosensitive belt 1 by the yellow laser unit 31 and the transfer roller 2). From the time required until the image is transferred to the sheet 29, the transfer roller 2
2 minus the time until the image is transferred: T in FIG.
In step 0), the hopper motor 24, the pick roller 18, and the transport rollers 16 and 17 are turned on to start picking the sheet 29 and transport the sheet 29 to the first registration roller 15. Here, the time when the leading end of the paper 29 passes the first transport roller 17 and the paper 29 can be fed by the first transport roller 17 and the second transport roller 16 is determined after the paper sensor 21 is turned on. Recognizing the time, the pick roller 18 is stopped, and the paper 29 is further transported by the first transport roller 17 and the second transport roller 16.
0, the first conveyance roller 17 and the second conveyance roller 16 are stopped after a predetermined time from when the sheet 29 passes and the sheet sensor 20 is turned on, and the sheet 29 is moved to the first registration roller 15 which is not rotated. At the point where it abuts, it is paused (t1, t21 in FIG. 2).

For a certain period of time from when the paper sensor 20 is turned on to when the first transport roller 17 and the second transport roller 16 are stopped, the paper 29 is abutted against the first registration roller 15, and a few mm By setting the transport time, if the leading edge of the paper 29 is not parallel to the first registration roller, its skew is corrected.

Further, after the yellow laser unit 31 is turned on and the electrostatic latent image is written on the photoreceptor belt 1 after a predetermined time (T1, T21 in FIG. 2), the first registration roller 15 is turned on. Then, the conveyance of the paper 29 is restarted. After the conveyance is resumed, the sheet 29 is abutted against the second registration roller 13 to correct the skew of the sheet 29, and the fourth conveyance roller 1 is fixed a certain time after the sheet sensor 19 is turned on.
4. Stop the first registration roller 15 (t in FIG. 2)
2, t22). Thereafter, after a predetermined time (T2, T22 in FIG. 2) from the start of writing the electrostatic latent image on the photosensitive belt 1 by turning on the yellow laser unit 31 and turning on the second registration roller 13, At the timing when the image drawn on the photoreceptor belt 1 is transferred to the sheet 29 by the transfer roller 2, the conveyance of the sheet 29 is restarted.

Here, the conveyance start time of the sheet 29 from the first registration roller 15 and the second registration roller 13 is not the time since the sheet sensors 20 and 19 are turned on, but the electrostatic latent image on the photosensitive belt 1. Is written on the basis of the time from the writing of the first registration roller 15 and the second registration roller 13 respectively. Thus, the position of the sheet 29 and the image can be accurately adjusted.

The time (T0 in FIG. 2) from the start of writing the image on the photosensitive belt 1 by the laser unit 3 to the start of picking the sheet 29 (T0 in FIG. 2), the writing of the image on the photosensitive belt 1 by the yellow laser unit 31 is started. From the time (t3 in FIG. 2) until the transfer to the transfer roller 2 from the time (t3 in FIG. 2), the time required to convey the sheet 29 from picking the sheet 29 to reaching the transfer roller 2 (FIG.
(T3-T0) is subtracted.

Next, a case where a transport delay of the paper 29 occurs due to a pick mistake of the paper 29 from the hopper 28 will be described with reference to the drawings.

FIG. 3 is a diagram showing the relationship between the position of the sheet 29 and the time during transport. Note that a solid line indicates when a pick error has occurred, and a two-dot chain line indicates a normal case when there is no pick error.

Referring to FIGS. 3 and 1, the picking operation of the sheet 29 is performed first, and if there is a pick error, the sheet sensor 21 does not turn on within a predetermined time, so that the second picking operation is performed. After the sheet 29 is picked and conveyed, when the leading end of the sheet 29 comes to the position of the first registration roller 15 (t1 in FIG. 3), it is the timing to start rotating the first registration roller 15 when it is already normal. Therefore, the stop of the sheet 29 is not performed, the stop time of the sheet 29 at the position of the second registration roller 13 (ts in FIG. 3) is shortened, and the time during which the conveyance of the sheet 29 is delayed is absorbed. As a result, the timing of starting to rotate the second registration roller 13 is the same as the timing when there is no pick mistake. Therefore, the delay of the sheet 29 after the second registration roller 13 is eliminated, and the alignment between the sheet 29 and the image is adjusted. Done exactly.

In the above embodiment, the paper 2
In the case where two registration rollers are provided to temporarily stop the printer 9, three or more registration rollers can be provided when the paper transport distance is long, such as when printing from an additional hopper. Needless to say, it is included in the invention.

[0044]

As described above, the image forming apparatus of the present invention is provided with a plurality of registration rollers for temporarily stopping the sheet conveyance and correcting the skew of the sheet and aligning the image. This has the effect of increasing the permissible amount of time and preventing displacement of the paper and the image due to the paper transport delay without reducing the printing throughput.

Further, by providing a plurality of registration rollers in the sheet transport path, the sheet skew correction is performed a plurality of times.
It is possible to correct a large skew of the sheet, which was not sufficient just by abutting the sheet against the registration roller once, and it is possible to more reliably correct the skew of the sheet.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating a relationship between a sheet position and time and a relationship between an image position on a photosensitive belt and time in the image forming apparatus of the present invention.

FIG. 3 is a diagram illustrating a relationship between a sheet position and time when a sheet pick error occurs in the image forming apparatus of the present invention.

FIG. 4 is a schematic configuration diagram illustrating a conventional image forming apparatus.

FIG. 5 is a diagram illustrating a relationship between a sheet position and time in a conventional image forming apparatus.

FIG. 6 is a diagram illustrating a relationship between a sheet position and time when a sheet pick error occurs in a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2 Transfer roller 3 Laser unit 31 Yellow laser unit (Y-LD) 32 Magenta laser unit (M-LD) 33 Cyan laser unit (C-LD) 34 Black laser unit (K-LD) 4 Developing device 41 Yellow developing device 42 Magenta developing device 43 Cyan developing device 44 Black developing device 11 Charging device 12 Eraser 13 Second registration roller 14 Fourth conveyance roller 15 First registration roller 16 Second conveyance roller 17 First conveyance roller 115 Third conveyance roller REFERENCE SIGNS LIST 18 pick roller 19, 20, 21 paper sensor 22 registration motor 23 feed motor 24 hopper motor 25 photoreceptor belt motor 26 information processing device 27 control unit 28 hopper 29 paper 50, 100 image forming device

Claims (11)

[Claims] 1. A photoreceptor belt on which an image is written, a charger for uniformly charging the surface of the photoreceptor belt, and a laser unit for exposing the surface of the photoreceptor belt to write an electrostatic latent image of each color. A developing device that develops the written electrostatic latent image of each color to form a toner image on the surface of the photoreceptor belt, a transfer roller that transfers the developed image to paper, and An eraser that removes the remaining charge, a hopper in which the paper is stored, a pick roller that picks up the paper from the hopper, a transport roller that transports the picked paper, and the paper that is transported from the transport roller A registration roller for temporarily stopping and correcting the skew of the sheet and the correction of the conveyance delay of the sheet; and the registration rollers provided near the pick roller and the registration roller, respectively. An image forming apparatus comprising: a paper sensor for detecting the presence / absence of paper; and a plurality of registration rollers provided between the pick roller and the transfer roller. 2. A photoreceptor belt on which an image is written, a charger for uniformly charging the surface of the photoreceptor belt, and a laser unit for exposing the surface of the photoreceptor belt to write an electrostatic latent image of each color. A developing device that develops the written electrostatic latent image of each color to form a toner image on the surface of the photoreceptor belt, a transfer roller that transfers the developed image to paper, and An eraser for removing the remaining charge, a hopper in which the paper is stored, a pick roller for picking the paper from the hopper, a first transport roller and a second transport roller for transporting the picked paper, and the first A first registration roller that temporarily stops the sheet conveyed from the conveyance roller and the second conveyance roller to perform skew correction of the sheet and correction of a conveyance delay of the sheet; A fourth transport roller that transports the paper after resuming the operation of one registration roller, and temporarily stopping the paper transported from the fourth transport roller to correct skew of the paper and correction of a transport delay of the paper. Registration rollers, a paper sensor provided in the vicinity of the pick roller, the first registration roller, and the second registration roller for detecting the presence or absence of the paper, and a photosensitive belt for rotating the photosensitive belt A motor, a registration motor that rotates the second registration roller, a feed motor that rotates the fourth conveyance roller and the first registration roller, the pick roller, the first conveyance roller, and the second conveyance roller. A hopper motor for rotating the
An image forming apparatus comprising: a control unit that controls the photoreceptor belt motor, the registration motor, the feed motor, the hopper motor, and the developing device. 3. The image forming apparatus according to claim 2, wherein the first registration roller and the second registration roller are arranged at a distance longer than a length of the sheet in the conveying direction. 4. The image forming apparatus according to claim 2, wherein the pick roller and the first registration roller are arranged at a distance interval longer than a length of the sheet in the conveying direction. 5. The image forming apparatus according to claim 2, wherein the first registration roller and the second registration roller correct a conveyance delay of the sheet by changing a stop time. 6. The method according to claim 2, wherein the first registration roller and the second registration roller each resume the paper conveyance after a predetermined time has elapsed from the start of writing an image on the photosensitive belt. Or the image forming apparatus according to 5. 7. A time period from the start of writing an image on the photosensitive belt by the laser unit to the start of picking of the sheet, the time between the start of writing an image on the photosensitive belt by the laser unit and the transfer roller. 3. The image forming apparatus according to claim 2, wherein a value obtained by subtracting a time required for conveying the sheet from picking of the sheet to reaching the transfer roller is subtracted from a time until the sheet is transferred to the sheet. . 8. The image according to claim 2, wherein the first transport roller, the second transport roller, the fourth transport roller, the pick roller, and the first registration roller each have a clutch. Forming equipment. 9. The image forming apparatus according to claim 1, wherein said laser unit comprises a yellow laser unit, a magenta laser unit, a cyan laser unit, and a black laser unit. 10. The image forming apparatus according to claim 1, wherein said developing device comprises a yellow developing device, a magenta developing device, a cyan developing device, and a black developing device. 11. The image forming apparatus according to claim 1, wherein the paper sensor is an optical sensor.