JPH09265220A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device equipped with recording-paper carrying means which achieves satisfactory carrying of recording paper, thereby realizing satisfactory image-linearity. SOLUTION: The image forming deuce, equipped with the recording paper carrying means which carries the recording paper by means of paper feed roller, stops it once in a resist position, and then recarries it, is provided with a recording-paper-carrying control means which exerts control in such a manner that the carrying of the recording paper stopping in the resist position is restarted by driving a resist roller 2 and while the carrying by the resist roller 2 is continued, the paper feed roller 1 pushes out the rear end part of the recording paper for a length of time TK after the carrying by the resist roller 2 is started and then a specific length of time TD elapses. Also, the device is provided with a plurality of paper feed parts having their own paper feed rollers 1, and the specific length of time TD or TK is set to different value depending on from which paper feed part the recording paper is supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a recording paper conveying means for temporarily stopping a recording paper fed to a transfer position at a registration position immediately before the transfer position in order to align an image forming start position on the recording paper. The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus capable of favorably conveying recording paper and maintaining image linearity.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus that forms an image on a recording sheet by transferring and fixing a toner image formed on a photosensitive drum or the like onto the recording sheet, the recording sheet is accurately timed. It is necessary to convey it to the transfer position. Therefore, first, the recording paper P is conveyed to the registration position R immediately before the transfer position T by the paper supply roller 21 shown in FIG. 8 and then stopped at the registration position R to set the timing of image formation on the photosensitive drum. The conveyance of the recording paper at the registration position is restarted by the registration roller 22 in synchronization with each other. When this conveyance is restarted, the rear portion of the recording paper to be conveyed is still at the position of the paper feed roller 21, but in one conventional technique,
At this time, the paper feed roller 21 simply rotates along with the movement of the recording paper. On the other hand, in another conventional technique, the paper feed roller 21 is restarted (driven) at the same time as the rotation of the registration roller 22, and the paper feed roller 21 is rotated for a predetermined time to push the recording paper. FIG. 9 is a timing chart showing the former conventional paper feeding operation. In FIG. 9, MMTR is a drive timing for rotating a drive motor (main motor) (High level is a drive period), and FDCL is a rotation of the drive motor. The feed roller
21 is the feed clutch on / off timing (High level), RGST is the paper presence (High level) signal from the registration sensor, and TRCL is the registration clutch on / off timing that transmits the rotation of the drive motor to the registration roller 22. Show. In other words, when the drive motor rotates and the feed clutch turns on, the paper feed roller 21
When the recording paper is conveyed and the recording paper reaches the registration position, the registration sensor detects the recording paper, and the feed clutch is turned off after a predetermined timing from the detection. In this way, after the recording paper is stopped at the registration position, the registration clutch is turned on and the registration roller 22 is rotated to convey the recording paper again. FIG. 10 is a timing chart showing the other conventional paper feeding operation. As shown in the figure, the feed clutch is turned on at the same time as the registration clutch is turned on, and the paper is fed for a predetermined time (0.2 seconds in the illustrated example). The roller 21 also rotates to push the recording paper.

[0003]

However, in the former prior art in which the sheet is not pushed by the sheet feeding roller when the conveyance from the registration position is resumed, the recording sheet may be skewed or slipped due to a problem such as conveyance. However, there is a problem in that the linearity of the image is impaired. Further, in the latter prior art in which the post-pressing is performed by the paper feed roller, although the problems as described above are improved, the optimum post-pressing timing varies depending on the type of the recording paper, etc. Conveyance · Good image linearity cannot be obtained. An object of the present invention is to solve the above-mentioned problems of the prior art and to realize an even better recording paper conveyance, thereby providing an image forming apparatus equipped with a recording paper conveyance means capable of realizing better image linearity. To provide.

[0004]

According to a first aspect of the invention, a recording sheet is conveyed by a sheet feeding roller toward a registration position where a registration roller exists, and when the leading end of the recording sheet reaches the registration position, the sheet feeding roller. In an image forming apparatus provided with a recording sheet conveying means for temporarily stopping the driving of the recording sheet and then starting the conveyance again, the registration roller is driven to restart the conveyance of the recording sheet which is stopped to the registration position, and only the registration roller is used. While carrying, the drive of the paper feed roller is restarted after a predetermined time TD has elapsed after the start of the carry by only the registration rollers and the drive of the paper feed roller is continued for the time TK, whereby the paper feed roller is It is characterized in that a recording paper conveyance control means for controlling so as to push the rear side of the recording paper is provided. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus includes a plurality of sheet feeding units each having an individual sheet feeding roller, and the predetermined time period TD depends on which sheet feeding unit the recording sheet is fed from. Alternatively, it is characterized in that the driving time TK of the paper feed roller is set to different values. According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, is it provided with a plurality of sheet feeding units each having an individual sheet feeding roller, and is controlled to start pushing by the sheet feeding rollers after a delay of a predetermined time TD? It is characterized in that whether or not each sheet is fed is set individually. According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, a recording sheet determination unit that determines the type of recording sheet to be conveyed is provided, and the recording sheet determination unit determines the type of the recording sheet determined by the recording sheet determination unit. It is characterized in that the time TD or the drive time TK of the paper feed roller is set to different values. According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, a recording paper determination unit that determines the type of recording paper to be conveyed is provided, and control is performed to delay the predetermined time TD and start the extrusion by the paper feed roller. It is characterized in that whether or not it is set individually for each type of recording paper.

[0005]

According to the image forming apparatus of the present invention, when the recording sheet is conveyed again from the registration position, the recording roller is conveyed by the registration rollers, and after the start of the conveyance by the registration rollers, a time TK has elapsed after a predetermined time TD has elapsed. Since the paper feed roller pushes out the rear side of the recording paper, good recording paper conveyance can be realized, and thereby better image linearity can be realized. In the image forming apparatus according to claim 2,
The predetermined time TD or TK can be set to different values depending on which paper feeding unit the recording paper is fed from. Therefore, it is possible to change the predetermined time TD or TK according to the conditions such as the size and direction of the recording paper stored in the paper feeding unit. It is possible to obtain the optimum paper feeding state. In the image forming apparatus according to the third aspect, it is possible to set, for each sheet feeding unit, whether or not to carry out the feeding by which the sheet feeding roller starts with a delay of the predetermined time TD after the sheet feeding by the registration rollers. It is possible to solve the problem that occurs when trying to do it. That is, it is possible to arbitrarily select according to individual conditions, and it is possible to improve image quality. In the image forming apparatus according to the fourth aspect, the predetermined time TD or TK can be set to different values according to the type, material, etc. of the recording paper to be supplied, so that the optimum paper feeding condition is set according to the paper quality. It becomes possible to do. In the image forming apparatus according to the fifth aspect, after the conveyance by the registration roller is started, it is possible to set whether or not the conveyance is started by delaying the predetermined time TD by the predetermined time TD for each kind of the supplied recording paper. It is possible to flexibly respond to differences in individual conditions.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 7 is a schematic configuration diagram of an image forming apparatus to which the present invention is applied. In the image forming apparatus having such a configuration, image formation is performed as follows. First, the recording paper is fed from the paper feed tray 3 by the paper feed roller 1, and when it reaches the registration position, the registration sensor 4 detects the arrival of the leading edge and stops at that position. on the other hand,
A latent image is formed on the photoconductor 6 by the laser light from the optical scanning device 5, and the latent image is caused by the toner from the developing device 7.
Then, in synchronization with the movement timing of the toner image on the photoconductor, the conveyance of the recording paper stopped at the registration position is resumed, and the toner image is transferred to the recording paper by the transfer charger 8. Further, fixing is performed by the fixing unit 9, and the sheet is discharged to the sheet discharge tray 10. FIG. 1 is a configuration block diagram of a main part of an image forming apparatus showing a first embodiment of the present invention. As shown in the figure, the image forming apparatus of this embodiment controls the entire apparatus, a drive motor 12 for rotating the paper feed roller 1, the registration roller 2, etc., and a rotation of the drive motor 12 for the paper feed roller 1. Feed clutch to transmit 1
3, a registration clutch 14 for transmitting the rotation of the drive motor 12 to the registration roller 2, an operation unit 15 and the like. Further, the control unit 11 has a CPU and a ROM having a control program built therein, and is provided with a recording paper conveyance control means constituted by them. The recording paper conveyance control means controls the start / stop of rotation of the drive motor 12, the on / off of the feed clutch 13 and the registration clutch 14, and the like.

FIG. 2 is an operation flow chart of this embodiment, and FIG.
The timing chart is shown in FIG. Note that the meanings of the signal names and the like shown in the timing chart are the same as those described in the section “Prior Art”. That is, the MMTR is a drive timing (Hi) for rotating the drive motor (main motor).
GH level is the driving period), the FDCL turns on the feed clutch (H which transmits the rotation of the driving motor to the paper feeding roller 1).
High level) / off timing, RGST is a paper present (High level) signal from the registration sensor, TRCL
Indicates the on / off timing of the registration clutch that transmits the rotation of the drive motor to the registration roller 2.

The operation of this embodiment will be described below with reference to FIG. First, the control section 11 gives an instruction to output to a recording sheet, whereby the recording sheet conveyance control means in the control section 11 starts the rotation of the drive motor 12 (S1) (MMTR: H
then turn on the feed clutch 13 (F
DCL: High). As a result, the rotation of the drive motor 12 is transmitted to the paper feed roller 1 and the paper feed roller 1 starts rotating (S2). In this way, the recording paper is delivered from the paper feed tray 3 (S3), and eventually the registration sensor 4 detects that the leading edge of the recording paper has reached the registration position (S4).
Yes) (RGST: High). When the detection signal of the registration sensor 4 is given to the recording paper conveyance control means,
The recording paper conveyance control means turns off the feed clutch 13 (FDCL: Low). Therefore, the paper feed roller 1 stops rotating and the conveyance of the recording paper stops (S5). on the other hand,
The image forming process as described above has started operating under the control of the control unit 11, and eventually a predetermined signal from this image forming process is received, that is, the image forming process is synchronized (Yes in S6). The registration clutch 14 is controlled by the control of the recording paper conveyance control means in response to a command from the control unit 11.
Turns on (TRCL: High). In this way, the registration roller 2 starts rotating, and the conveyance of the recording paper is restarted (S7). Further, at this time, the recording paper conveyance control means starts the timer in the control section 11.

Thereafter, the recording paper conveyance control means monitors that the timer measures a predetermined time (waiting time from the restart of the registration roller drive to the restart of the feed roller drive) TD (S8 → S8). Then, when the predetermined time TD has elapsed (Yes in S8), that is, after a delay of TD from the rotation start of the registration rollers 2, the feed clutch 13 is turned on again (FDCL: High). Therefore, the paper feed roller 1 starts to rotate again (S9). Thus, the recording paper is not only conveyed by the rotation of the registration roller 2, but also pushed by the rotation of the paper feed roller 1. Also,
The recording paper conveyance control means resets the timer at the same time as turning on the feed clutch 13 and restarts it, and monitors that the timer measures a predetermined time TK (S10 → S10).
Then, when a predetermined time (driving time of the paper feed roller for which driving is restarted) TK has elapsed (Yes in S10), the feed clutch 13 is turned off again (FDCL: Low), and the rotation of the paper feed roller 1 is stopped (S11). ). Therefore, thereafter, the paper feed roller 1 is rotated together until the trailing edge of the recording paper leaves the paper feeding roller 1, and eventually the trailing edge of the recording paper also leaves the registration position and the registration sensor 4 is turned off (RGS
(T: Low), the recording paper conveyance control means turns off the registration clutch 14 (TRC) after separating from the registration roller 2.
L: Low), the rotation of the registration roller 2 is stopped (S12). In addition, in parallel with the above operation, the transfer to the recording paper is performed, then the fixing is performed, and the recording paper is transferred to the discharge tray 10.
(S13). Thus, according to this mode example, when the recording sheet is conveyed again from the registration position, the pushing force of the recording sheet by the sheet feeding roller 1 is adjusted to the type (paper quality) of the recording sheet to be used, the condition (size, direction), etc. Therefore, the recording paper can be conveyed without skew or slippage, and the linearity of the image can be maintained.

In the second embodiment of the present invention, as shown in the schematic view of FIG. 4, individual paper feed rollers 1a-1c are provided.
Paper feed trays (not shown) corresponding to (three examples)
In an image forming apparatus having a plurality of paper feeding units
The recording paper conveyance control means has a control table as shown in FIG. The sheet feeding units A, B and C shown in FIG. 5 correspond to the sheet feeding rollers 1a, 1b and 1c (FIG. 4). As is clear from FIG. 5, in this embodiment, the predetermined time TD and the driving time TK of the paper feed roller are varied depending on which paper feed unit the recording paper is fed from and the type of the recording paper. . Further, in FIG. 5, RF means control of the paper feed roller when the conveyance from the registration position is restarted, and
Indicates that the paper feed roller 1 is driven (rotated), and x indicates that it is not driven. paper 1-3 are
It means the type (material) of recording paper, and each paper feed unit A,
Optimal predetermined times TD and TK according to the types of recording papers stored in B and C are shown, respectively. Such a control table is created beforehand in the control unit 11 by inputting data from the operation unit 15 or the host computer (when the image forming apparatus is used as an output-only printer), and the recording paper conveyance control unit , The predetermined time TD and TK are set by referring to this control table when the recording paper is conveyed. In addition,
The recording paper conveyance control means determines the paper feed unit to which the recording paper is supplied and the type of the recording paper in order to set TD and TK.

The determinations regarding the sheet feeding units A, B, and C are as follows.
For example, it is performed according to the size of the recording paper used. Each paper feed tray of each paper feed unit has a size sensor,
When the recording paper is stored in this paper feed tray, the size of the stored recording paper is detected, and the control unit 11 sets the recording paper size in the recording paper table associated with each paper supply unit in accordance with the detected size. . Further, the type of recording paper is set by the user from the operation unit 15 or the like when the recording paper is stored in the respective paper feed trays or when the recording paper is of a different type. FIG.
Is an example of the recording paper table set in this way. Consider a case where an output operation to recording paper occurs in the state where such a table is created. If this image forming apparatus is a copying machine, the control unit 11 can know the recording paper size from the size of the document. If the image forming apparatus is a printer, the control unit 11 acquires the recording paper size in response to a print command from the host computer. And
Data about the acquired recording paper size is passed to the recording paper conveyance control means. For example, if the recording paper size is A4, the recording paper conveyance control unit refers to the recording paper table as shown in FIG. 6, the paper feeding unit is A, and the paper type is pap.
It is determined to be er1.

Therefore, in the case of the above example, the recording paper conveyance control means turns on the feed clutch 13 belonging to the paper feed section A to rotate the paper feed roller 1a to feed the recording paper from the paper feed section A. Then, when the recording paper is conveyed again from the registration position, it is more than 0.2 from the start of rotation of the registration roller 2.
After delaying for 2 seconds, the paper feed roller 1a is rotated again to 0.4.
The paper feed roller 1a is rotated only for a second (see FIG. 5). Thus, according to the second embodiment, when the recording sheet is re-conveyed from the registration position,
Further, since the timing of pushing the recording paper by the paper feed roller 1 can be automatically changed and controlled depending on the type of the supplied recording paper, skew and slippage of the recording paper can be further prevented, and thus the linearity of the image can be improved. Can be further improved.

By the way, as described above, the information RF is set in the control table shown in FIG. 5, but if this information indicates negative (x mark), even TK or TD is set. However, it is also possible not to drive (back-press) the paper feed roller 1 when the recording paper is re-conveyed from the registration position. The RF is set in advance by the user from the operation unit 15 or the like, and when the recording paper is re-conveyed from the registration position, the recording paper conveyance control means first refers to the RF information when referring to the control table. And R
If the F information indicates negative, the recording paper is unconditionally conveyed only by the registration roller 2. On the other hand, if the RF information is affirmative (marked with ◯), the recording paper is conveyed with the backing by the paper feed roller 1 according to the set TD and TK.

[0014]

As described above, according to the present invention,
In the image forming apparatus according to claim 1, when the recording sheet is conveyed again from the registration position, the recording sheet is conveyed for a time TK after a predetermined time TD elapses after the conveyance by the registration roller is started while the conveyance by the registration roller is started. Since the roller pushes the rear side of the recording paper, appropriate control for preventing skew and slippage of the recording paper can be performed, and thus the linearity of the recorded image is improved. In the image forming apparatus according to the second aspect, the predetermined time TD or TK can be set to different values depending on which paper feeding unit the recording paper is supplied from. Therefore, the conditions such as the size and the direction of the recording paper can be satisfied. Corresponding to the difference, the control for preventing the skew and slip of the recording paper can be more appropriately performed.

In the image forming apparatus according to the third aspect of the present invention, it is possible to set, for each paper feeding unit, whether or not to carry out the transportation of starting the extrusion by the paper feeding roller after delaying the transportation by the registration rollers by a predetermined time TD. It is possible to deal with it.
In the image forming apparatus according to the fourth aspect, the predetermined time TD or TK can be set to different values according to the type (material, etc.) of the recording paper to be supplied, so that the skew or slip of the recording paper can be prevented. The control can be performed more appropriately. In the image forming apparatus according to claim 5, after the conveyance by the registration roller is started,
Since it is possible to set for each type of recording paper to be supplied whether or not to carry out the start of the extrusion by the paper feed roller after delaying by the predetermined time TD, it is possible to flexibly deal with it.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a main part of an image forming apparatus showing a first embodiment of the present invention.

FIG. 2 is an operation flowchart of a main part of the image forming apparatus showing the first embodiment of the present invention.

FIG. 3 is a timing chart of essential parts of the image forming apparatus showing the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a main part of an image forming apparatus showing a second embodiment of the present invention.

FIG. 5 is a data configuration diagram of a main part of an image forming apparatus showing a second embodiment of the present invention.

FIG. 6 is another data configuration diagram of the main part of the image forming apparatus showing the second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an image forming apparatus in which the present invention is implemented.

FIG. 8 is an explanatory diagram of a main part of an image forming apparatus showing an example of a conventional technique.

FIG. 9 is a timing chart of a main part of an image forming apparatus showing an example of a conventional technique.

FIG. 10 is a timing chart of the main part of the image forming apparatus showing another example of the conventional technique.

[Explanation of symbols]

 1 Paper Feed Roller 2 Registration Roller 3 Paper Feed Tray 4 Registration Sensor 11 Control Unit 13 Feed Clutch 14 Registration Clutch 15 Operation Unit

Claims (5)

[Claims] 1. A recording sheet is conveyed by a sheet feeding roller toward a registration position where a registration roller exists, and when the leading edge of the recording sheet reaches the registration position, the driving of the sheet feeding roller is once stopped and then the conveyance is restarted. In an image forming apparatus equipped with a recording paper conveying means for driving, the registration roller is driven to restart the conveyance of the recording paper which has been stopped to the registration position, and the conveyance by only the registration roller is carried out while the conveyance by only the registration roller is carried out. Recording for controlling the paper feed roller to push out the rear side of the recording paper by restarting the drive of the paper feed roller after the start of a predetermined time TD and continuing the drive of the paper feed roller for the time TK An image forming apparatus comprising a paper conveyance control means. 2. The image forming apparatus according to claim 1, further comprising a plurality of paper feed units each having an individual paper feed roller, and the predetermined time TD or the paper feed depending on which paper feed unit feeds the recording paper. An image forming apparatus characterized in that the driving time TK of the paper roller is set to different values. 3. The image forming apparatus according to claim 1, further comprising a plurality of paper feed units each having an individual paper feed roller, and whether or not control is performed to delay the predetermined time TD and start extrusion by the paper feed rollers. An image forming apparatus having a configuration in which each of the sheet feeding units is individually set. 4. The image forming apparatus according to claim 1, further comprising a recording paper determination unit that determines a type of recording paper to be conveyed,
An image forming apparatus characterized in that the predetermined time TD or the drive time TK of the paper feed roller is set to a different value according to the type of recording paper judged by the recording paper judging means. 5. The image forming apparatus according to claim 1, further comprising a recording paper determination unit that determines the type of recording paper to be conveyed,
An image forming apparatus having a configuration in which whether or not to perform control to start pushing by a paper feed roller after a delay of a predetermined time TD is set individually for each type of recording paper.