JPH10312144A - Image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate a copying error and a missing copy of an original, and to store a blank transferred object in a copied transferred object even when there is only one storage tray. To provide an image forming apparatus capable of preventing image formation. SOLUTION: A reading means 1 for reading a document image, a photoreceptor 2 for obtaining a read image as a visible image through an electrostatic process of charging, exposing, and developing, and a photoreceptor for transferring a transfer target from a paper feeding unit A pair of registration rollers 3 for feeding the visible image on the pair 2 at the same time; and a delay detection unit 4 for detecting a time delay of the transfer target body reaching the pair of registration rollers 3 from the paper feeding unit.
When the detected time delay is within a predetermined range, the obtained visible image is invalidated, the invalidated original image is read again, and the timing is adjusted to the obtained visible image. Drive control means 5 for controlling the driving of the pair of registration rollers.

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 such as a black-and-white electrophotographic copying machine, a color electrophotographic copying machine, a laser printer, a facsimile, and the like, and more particularly, to detecting a time delay of a transfer member reaching a registration roller pair. The present invention relates to an image forming apparatus having a delay detection function.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus having a function of detecting a delay of a transfer target such as a recording paper, it has been detected that a registration roller pair cannot be reached from a paper feeding unit within a predetermined time. In such a case, this is treated as occurrence of a jam, the driving of the transport system is temporarily stopped, and the apparatus waits until the object to be transferred is taken out. This jam is roughly divided into two cases. One is a case where the transfer target is caught in the course of conveyance or a skew occurs and a paper jam is truly generated. The other case is a case where the time to reach the registration roller pair is slightly delayed due to the influence of paper dust or dust, the reduction in the transfer force of the transfer roller, or the reduction in the friction coefficient of the transfer target. In the former case, it is impossible to convey even if it waits any longer, and it is necessary to stop the driving force of the conveyance system and wait for the transfer target to be taken out, but in the latter case, change the jam detection time, This can be handled by changing the control sequence, so that the object to be transferred is not wasted and the operation does not need to be stopped each time. As a technique corresponding to the latter case, there is a technique described in JP-A-60-93464.
According to this, when the transfer target sent out from the paper feeding unit is present in the registration unit at a timing other than the predetermined timing, the remaining transfer target remaining in the transport path between the paper feeding unit and the registration unit is discharged. As a result, the transferred object having the jam entering the cleaning unit may damage the cleaning unit, or the control sequence may be different depending on the remaining transferred object so that the jam is continuously detected. Troubles can be prevented.

[0003]

As described above, in the conventional image forming apparatus, the driving force of the transport system is stopped when it is determined that a jam occurs even when the time for the transfer target to arrive at the registration roller pair is slightly delayed. Is very inefficient,
In addition, there is a problem that wrinkles and tears are generated when the transfer target is taken out, and the transfer target is wasted. Further, when the transfer target sent out from the paper feeding unit is present in the registration unit at a timing other than the predetermined timing, a process for discharging the remaining transfer target remaining in the conveyance path between the paper feeding unit and the registration unit is performed. According to the method described in the above publication, during the continuous reading, the next document is read by the reading unit while the copy of the document corresponding to the transfer target in which the jam has occurred is missing, or there is only one storage tray. In this case, the blank transfer medium ejected together with the copied transfer medium is ejected and stored together. Therefore, an object of the present invention is to reduce the time required for the transfer object to reach the registration roller pair within a predetermined range because the transfer force of the transfer roller is significantly reduced or the friction coefficient of the transfer object is reduced. In this case, after performing an empty scan once, the same original image is read again, and the registration roller pair is driven to transfer the timing to the visible image on the photoconductor, thereby transferring the image. The present invention provides an image forming apparatus which can eliminate the omission of copying, and can prevent the problem that a blank transfer target is mixed and stored in a copied transfer target even when there is only one storage tray. .

[0004]

According to another aspect of the present invention, there is provided an image forming apparatus having a function of reading a document image and forming an image on a transfer target. A reading means for reading a document image, a photoreceptor for obtaining an image read by the reading means as a visible image through an electrostatic process of charging, exposure and development, and a transferred body conveyed from a paper feeding unit A pair of registration rollers for feeding the registration roller with the visible image on the photosensitive member at the same time, a delay detection unit for detecting a time delay of the transfer target body reaching the registration roller pair from the paper supply unit, and the delay When the time delay detected by the detecting means is within a predetermined range, the visible image obtained by the reading means is invalidated, and the invalidated original image is read again by the reading means, and It said in which said being constituted by a drive control means for controlling the driving of the registration roller pair to match the visible image and the timing on the photosensitive member.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when the time delay detected by the delay detection unit is within a predetermined range, a warning display unit that displays a warning of a transport abnormality is provided. It is configured to further be provided.

[0005]

According to the above configuration, in the image forming apparatus according to the first aspect of the present invention, when a time delay of the transfer target body reaching the registration roller pair from the paper feeding unit is detected in a predetermined range. Invalidating the visible image obtained by the reading unit by the drive control unit, reading the invalidated original image again, and adjusting the registration so as to match the timing with the obtained visible image on the photoconductor. Since the driving of the roller pair is controlled, the transfer is correctly performed on the transferred object which is delayed at the time of the second reading, so that there is no copying error or missing copy of the original, and further, the blank transferred object is stored in the storage tray as it is. The problem of that is also eliminated. Further, in the image forming apparatus according to the second aspect of the present invention,
In addition to the configuration described in the above, when the time delay detected by the delay detection means is within a predetermined range, the warning display means to display a warning of the conveyance abnormality, so that paper dust in the apparatus and It is possible to take quick action such as cleaning of dust and the like, prohibition of the use of the transferred object having a low coefficient of friction, or replacement of parts due to a decrease in the conveying force of the conveying roller.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a side sectional view showing an example of an embodiment of an electrophotographic copying machine (hereinafter, referred to as a copying machine) which is a kind of an image forming apparatus according to the present invention. In FIG. 1, originals stacked on an original feeder table 12 of an automatic original feeder 11 are read one by one by driving an original feed roller 13 and an original feed belt 14 interlocked therewith. The document is transported onto the table 15 and read by the reading unit 1. The reading unit 1 includes a light source group 1a including a light source and a first mirror for guiding reflected light from a document to a subsequent stage, and a front-stage mirror group 1b for guiding light from the light source group 1a to a subsequent stage by a plurality of mirrors. , A lens group 1c for condensing the received light, a rear mirror group 1d including a plurality of mirrors for reflecting the light from the lens group 1c and guiding the light in the opposite direction, and a photosensitive drum for the light of the rear mirror group 1d. 2 is constituted by an exposure mirror 1e and the like leading to a predetermined position on the exposure mirror 1e. The positions of the lens group 1c and the rear mirror group 1d are set according to the magnification at the time of image formation. During reading, the light source group 1a scans the stationary document at a speed of v, and at the same time, moves the front mirror group 1b v / v.
Scan at 2 speeds. The light that has exited the exposure mirror 1e is uniformly charged in advance and is rotating.
Exposure is performed thereon to form an electrostatic latent image corresponding to the image. Next, the electrostatic latent image formed on the photosensitive drum 2 is visualized by the toner of the developing unit 16 as the photosensitive drum 2 rotates (in the direction of the arrow).

On the other hand, the paper supply unit 17 includes a plurality of paper supply cassettes (17a, 17b, 17
c, 17d). The transfer medium supplied from one of the paper feed cassettes is fed to the paper feed roller pair 18 (18).
a, 18b, 18c, 18d), a pair of sheet feeding / conveying rollers 19
(19a, 19b, 19c, 19d) and the like, are conveyed in the direction of the photosensitive drum 2 and stopped by the registration roller pair 3, and the registration roller pair 3 is used to transfer the leading end of the transfer-receiving body and the leading end of the image on the photosensitive drum 2. Are sent at the same timing, the toner image on the photosensitive drum 2 is transferred onto the transfer target. Further, the toner image transferred onto the transfer medium is heat-fixed by the fixing unit 20 and stored in one of the predetermined storage trays 21. The copying machine shown in FIG. 1 has a double-sided copying function. For this purpose, a double-sided unit 22 for reversing the transferred body is provided. The transferred body, one side of which is transferred by the photosensitive drum 2 and is heat-fixed by the fixing unit 20, is transferred to the lower double-sided unit 22 by the branching claw 23. The sheet is conveyed into the duplex unit 22 with the transfer surface down by the action of the duplex unit storage roller 24 and the duplex unit transport roller 25. Thereafter, the image is transferred to the bottom of the double-sided unit 2 (indicated by a dotted line), and the transfer object is stored by being inverted by the double-sided unit reversing roller 26.

Next, the double-sided unit reversing roller 26 rotates in the opposite direction to send out the previously stored object to be transferred from the double-sided unit 22, and the registration roller pair 3 causes the image to be transferred to the tip of the object to be transferred and the image on the photosensitive drum 2. The leading end is sent out at a proper timing, the opposite surface of the transfer-receiving body is transferred by the photosensitive drum 2, and the toner image is fixed by the fixing unit 20.
It is stored in one of the storage trays 21. In this manner, double-sided copying is performed on the transfer target. Also, the illustrated copying machine
There are four types of paper feed cassettes 17a, 17b, 17c, and 17d for storing transfer media having different sizes and transport directions so that copying can be performed on transfer media of various sizes according to the document. The type of transfer object stored in which paper cassette is recognized by the size detection (not shown) attached to each paper cassette, and is displayed on the operation display unit 6 so that it can be easily determined. ing. The operation display unit 6 also includes a warning display unit 6a that displays a warning when a transport error occurs.

The operation display section 6 is provided with a paper cassette selection switch (not shown) so that a paper cassette can be selected in accordance with the size of the object to be transferred and the transport direction during a copying operation. . Further, a paper feed cassette automatic selection switch is provided so that a paper feed cassette containing an optimum transfer medium can be automatically selected according to the document size and the printing magnification. Further, a control printed circuit board 7 for controlling the operation of each part of the image forming apparatus is installed below the sheet feeding cassette 17a. The control printed circuit board 7 includes a CPU,
In addition to the ROM and the RAM, various circuits for controlling the operation of each unit are arranged together. Further, a delay detection unit 4 for detecting a time delay of the transfer object is provided in front of the registration roller pair 3 in the transport direction, and an output of the delay detection unit 4 is connected to the control printed circuit board 7. Further, a drive controller 5 is provided between the control printed board 7 and the registration roller pair 3.

Here, the operation of the copying machine constructed as described above according to the present invention will be described. Documents stacked on the document feeder table 12 of the automatic document feeder 11 are conveyed one by one onto a reading platen 15 for reading, and are read by the reading unit 1. The movement of each component of the reading unit 1 when reading a document has already been described, and a description thereof will be omitted. The read image light is exposed on the photosensitive drum 2 to form an electrostatic latent image corresponding to the image. Further, the electrostatic latent image formed on the photosensitive drum 2 is visualized by the toner of the developing unit 16 as the photosensitive drum 2 rotates (in the direction of the arrow). On the other hand, the transfer object is conveyed from one sheet cassette of the sheet feeding section 17 in the direction of the registration roller pair 3 by driving the sheet feeding roller pair 18 and the sheet feeding roller pair 19. Immediately before the pair of registration rollers 3, a delay detection unit 4 for detecting a time delay of the transfer object is provided. You are measuring time. This arrival time varies greatly depending on wrinkles and tears of the transfer target, obstacles such as paper dust and dust on the transfer path in the middle, or a reduction in the transfer force of the transfer rollers and a reduction in the friction coefficient of the transfer target. The more the wrinkles and tears of the transferred object, the obstacles such as paper dust and dust, or the lowering of the conveying force and the lowering of the coefficient of friction, the longer the arrival time becomes, and finally, the state becomes impossible to convey. In the present invention, a predetermined delay time range is set. The range of this delay time is
Since the sheet has reached the registration roller pair 3, the sheet is not treated as a jam, but is within a range in which timing for transferring a visible image already formed on the photosensitive drum 2 is delayed.

Accordingly, if the delay time is within the above-mentioned predetermined range, the visible image formed on the photosensitive drum 2 is removed by the cleaning unit 27 by the operation of the drive control unit 5, and the charging is performed. The surface of the photosensitive drum 2 is uniformly charged by the charger 28. Thereafter, the original is left as it is, and the scanning unit 1 is again scanned to read the original image, exposed on the photosensitive drum 2 to form an electrostatic latent image corresponding to the image, and the toner of the developing unit 16 is used. Visualize the image. Further, the registration roller pair 3 is driven in synchronization with the visible image on the photosensitive drum 2 obtained in the second reading, and an image is formed on the delayed transfer target.

When the delay detecting section 4 detects a time delay within a predetermined range, a warning is displayed on the warning display section 6a of the operation display section 6 to indicate that a transport abnormality has occurred. That is, the control printed circuit board 7 and the warning display section 6a are connected to each other by a signal line (not shown), and the above warning display is performed according to an instruction from the CPU on the control printed circuit board 7. In response to this warning message, the user can take quick action by cleaning paper dust and dust inside the device, prohibiting the use of transfer media with a low coefficient of friction, or replacing parts due to a decrease in the transport force of the transport rollers. For example, downtime of the image forming apparatus can be reduced. FIG. 2 is a flowchart showing the operation of the copying machine shown in FIG. 1 (corresponding to claim 1). Hereinafter, the operation of the present embodiment will be described with reference to this flowchart. First, the first step S
In step 1, it is checked whether or not the start switch on the operation display section 6 has been pressed, that is, whether or not a document has already been set on the document table 15 and a document image reading request has been issued. Then, the process waits until the start switch is pressed (No in S1). When the start switch is pressed (Yes in S1), the process proceeds to the next step S2. In step S2, the reading unit 1 starts reading a document image set on the document table 15, an electrostatic latent image corresponding to the image is formed on the photosensitive drum 2, and is further statically charged by the toner of the developing unit 16. The electric latent image is visualized.

In the next step S3, the transfer object is supplied from one of the paper feed cassettes of the paper feed unit 17, and the direction of the photosensitive drum 2 is assisted by the paper feed roller pair 18, the paper feed roller pair 19 and the like. At the position of the registration roller pair 3, the timing of the leading end of the transfer-receiving member and the leading end of the image on the photosensitive drum 2 are adjusted. After exiting the paper feed start routine (S3), it is checked whether or not the timing for driving the registration roller pair 3 has come from the rotation state of the photosensitive drum 2 (S4). Then, it waits until the timing time for driving the registration roller pair 3 has come (No in S4), and when the timing time comes (Yes in S4), the next step S5
Proceed to. In step S5, the delay detecting unit 4 determines whether or not the transferred object has reached the registration roller pair 3, and if the transferred object has reached the registration roller pair 3 (Yes in S5), step S6. Proceed to. Step S6
Then, the start of the transfer of the transfer object stopped by the registration roller pair 3 is started by the tip of the transfer object and the photosensitive drum 2
Make sure that the top of the image above matches the timing
Proceed to the next step S7.

In step S7, the transfer object is separated from the photosensitive drum 2 by a separation charger or separation claw (not shown), and the toner image transferred onto the transfer object by the action of the fixing unit 20 is thermally fixed. Storage tray 2 determined in advance
Store in one of the ones. Also, in step S5,
If the transfer target does not reach the registration roller pair 3 even when the registration roller pair 3 is driven (No in S5), the process proceeds to step S10, and the time of the transfer target reaching the registration roller pair 3 is reached. It is checked whether or not the delay is within a predetermined range (S10). If the time delay of the transfer target is out of the predetermined range (No in S10), the process proceeds to step S11. In this step S11, the driving of the transport roller system is completely stopped,
A warning that a transport error has occurred is displayed on the operation display unit 6,
Wait for the jammed transfer object to be removed. In step S10, if the time delay of the transfer target is within a predetermined range (Y in S10).
es) The transfer of the visible image formed on the photosensitive drum 2 due to the delay of the transfer target is delayed in timing, so that the cleaning unit 27 removes the visible image. , The photosensitive drum 2 by the charging charger 28
The surface is uniformly charged (S8). Thereafter, the original to be read is left as it is, and the reading unit 1 is again scanned to read the original image, and is exposed on the photosensitive drum 2 to form an electrostatic latent image corresponding to the image. (S9). Then, it is checked whether or not it is time to start the pair of gyst rollers 3 to transfer the image on the photosensitive drum 2 obtained by the second reading (S4). It waits until the timing to drive the registration roller pair 3 is reached (No in S4), and at that timing (Yes in S4), the next step S5
The delay detecting unit 4 determines whether or not the transferred object has reached the registration roller pair 3. As a result, if the transfer object has reached the registration roller pair 3 (Yes in S5), the transfer object on which an image has been formed is obtained through steps S6 and S7 in the same manner as described above.

FIG. 3 is a flowchart showing another operation of the copying machine shown in FIG. 1 (corresponding to claim 2). The difference from the flow shown in FIG.
8, except that step S12 is newly added, and the other operations are as described in FIG. In the flow shown in FIG. 3, even when it is time to drive the registration roller pair 3, the transfer target body has not reached the registration roller pair 3 (No in S <b> 5), and has reached the registration roller pair 3. If the time delay is within a predetermined range (Yes in S10), a warning is displayed on the warning display section 6a of the operation display section 6 that a transport abnormality has occurred (S12). Therefore, the user who sees the warning display can quickly respond by cleaning paper dust and dust in the apparatus, prohibiting the use of a transfer object having a low coefficient of friction, or replacing parts due to a decrease in the conveying force of the conveying rollers. , The downtime of the image forming apparatus can be reduced. Although the above embodiment is directed to a copying machine, the image forming apparatus of the present invention can be effectively applied not only to a copying machine but also to a laser printer, a facsimile, or a multifunction machine having these functions. it can.

[0016]

As described above, according to the present invention, the following excellent effects can be exhibited. According to the image forming apparatus of the first aspect, when the time delay of the transfer target body reaching the registration roller pair from the sheet feeding unit is detected in a predetermined range, the time delay is obtained by the reading unit. The visible image is invalidated, the invalidated original image is read again, and the drive of the registration roller pair is controlled so as to match the timing with the obtained visible image on the photoconductor. The transfer is correctly performed on the transferred object, and a copy error and a missing copy of the original are eliminated, so that a highly reliable image can be formed. In addition, since there is no problem that the object to be transferred is stored in the storage tray in a blank state, it is not necessary to remove the object to be transferred later. According to the image forming apparatus of the present invention, in addition to the first aspect, when a time delay of the transfer target body reaching the registration roller pair is detected in a predetermined range, Is displayed to notify the user that the user has cleaned the paper dust and dust inside the device, prohibited the use of the transfer object with a low coefficient of friction, or reduced the transport force of the transport rollers. Quick response before failure by replacement etc. can be done,
Downtime can be reduced, and more reliable image formation can be performed.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of an embodiment of an electrophotographic copying machine which is a kind of an image forming apparatus according to the present invention.

FIG. 2 is a flowchart showing an operation content of the copying machine shown in FIG. 1;

FIG. 3 is a flowchart showing another operation content of the copying machine shown in FIG. 1;

[Explanation of symbols]

1 reading unit, 1a light source group, 1b front mirror group, 1c
Lens group, 1d rear mirror group, 1e exposure mirror, 2 photoreceptor drum, 3 registration roller pair, 4 delay detection section, 5 drive control section, 6 operation display section, 6a warning display section, 7 control printed circuit board.

Claims (2)

[Claims] 1. An image forming apparatus having a function of reading a document image and forming an image on a transfer-receiving member, comprising: a reading unit for reading a document image; A photoreceptor that obtains a visible image through an electrical process, a pair of registration rollers that feeds the transfer target conveyed from the paper supply unit to the transfer unit in time with the visible image on the photoreceptor, and a paper supply unit A delay detecting means for detecting a time delay of the object to be transferred reaching the registration roller pair; and a time delay obtained by the reading means when the time delay detected by the delay detecting means is within a predetermined range. The visible image is invalidated, the invalidated document image is read again by the reading means, and the registration roller pair is driven so as to match the timing with the obtained visible image on the photoconductor. An image forming apparatus comprising: the drive control means for controlling, the. 2. The image forming apparatus according to claim 1, further comprising a warning display unit that displays a warning of a conveyance abnormality when a time delay detected by the delay detection unit is within a predetermined range. An image forming apparatus comprising: