JP3367317B2 - Image forming device - Google Patents

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 copying machine or a printer for forming an image on a sheet, and more specifically, a stapling process or a punching process for a plurality of stacked sheets. The present invention relates to an improvement in an image forming apparatus having a post-processing unit that performs post-processing.

[0002]

2. Description of the Related Art Heretofore, an image forming apparatus of this type has, for example, an image forming section for forming an image on a sheet, a discharge sheet tray on which a plurality of sheets on which an image has been formed are stacked, and a sheet discharged from the image forming section. It has a sheet discharging / conveying unit that conveys a sheet to a sheet tray, and a post-processing unit that performs a post-processing such as a stapling process on the plurality of sheets stacked on the discharged sheet tray.

Further, the image forming section forms, for example, a latent image by rotatably arranging an image carrier, charging means for uniformly charging the image carrier, and exposing the image carrier. Exposure means, a developing means for adhering toner to the latent image to form a toner image, a transfer means for applying a transfer voltage between the image carrier and the transfer means for transferring the toner image onto a sheet, And a fixing unit configured to heat and press the sheet to fix the toner image as an image on the sheet. Then, in the image forming section, while rotating the image carrier at a constant peripheral speed, charging, exposure, development and transfer are performed to form an image on a sheet.

Therefore, in the image forming apparatus, an image is formed on a sheet at every rotation cycle of the image carrier, that is, the sheet is formed at a constant image forming cycle corresponding to the operation cycle of the image forming section. An image is formed on the sheet, and eventually the sheet is discharged onto the discharged sheet tray at a constant image forming cycle corresponding to the operation cycle of the image forming unit.

Therefore, it is necessary for the post-processing means to complete the post-processing within the fixed image forming cycle corresponding to the operation cycle of the image forming section. It should be noted that the above-mentioned post-processing unit must actually complete the post-processing after the sheet is positioned at a predetermined position on the discharge sheet tray and before the next sheet is discharged to the discharge sheet tray. It is necessary to complete the post-processing within a time much shorter than the image forming cycle.

[0006]

However, in such an image forming apparatus, when the operation cycle of the image forming section is improved and the image forming cycle is shortened, the discharge interval of the paper to the discharge paper tray is accordingly increased. Becomes shorter and the post-treatment cannot be completed within the discharge interval.

Therefore, in the conventional image forming apparatus,
In addition to improving the operation cycle of the image forming unit, when performing the post-processing, the image forming unit is made to perform an idle operation once, that is, the image forming unit executes a dummy cycle in which an image is not formed on the paper. As a result, in the image forming apparatus, it is possible to secure a sufficient discharge interval between the sheet discharged to the discharge sheet tray before performing the post-processing and the sheet discharged to the discharge sheet tray after performing the post-processing. The post-treatment can be completed in the meantime.

However, if the operation matching of the image forming apparatus is attempted by such a method, the capability of the image forming section cannot be fully exhibited.

Therefore, an object of the present invention is to develop an image forming apparatus having a post-processing means and capable of sufficiently exhibiting its capability even if an image forming section having a fast operation cycle is used.

[0010]

That is, the present invention is
An image forming unit that forms an image on paper, a paper ejecting unit that ejects the paper, a paper ejecting and conveying unit that conveys the paper from the image forming unit to the paper ejecting unit, and post-processing of the paper in the paper ejecting unit. In the image forming apparatus having a post-processing unit for performing, the paper discharge / conveyance unit includes the image forming unit and the paper discharge unit.
The shortest sheet discharge device that is provided between the
It is placed facing the exit path and this shortest paper discharge path,
Conveying paper consisting of a pair of conveying rollers that can rotate forward and backward
Paper reversal discharge path having reversal conveyance means for reversing direction
And the sheet discharging and transporting section is
When a post-processing of two or more parts is performed, the first part of the next part
Paper from the shortest paper discharge path to the paper reverse discharge path
, And then temporarily stop
Stop and reverse rotation of the transport roller after a specified waiting time.
Further , the image forming apparatus is characterized in that it is discharged from the sheet inversion discharge path to lengthen the transport time of the first paper.

The sheet transport time is the time from when the leading edge of the sheet is carried into the sheet discharging and transporting section until when the trailing edge of the sheet is transported out of the sheet discharging and transporting section.

The above-mentioned sheet discharging and conveying section can convey the sheet from the image forming section to the sheet discharging section, and if the post-processing means can carry out the post-processing, the time for conveying the next sheet can be extended. Of course, for example, it can be constituted by a plurality of sheet conveying means arranged along the shortest sheet discharging path from the image forming section to the sheet discharging section and a sheet conveying control means for controlling the plurality of sheet conveying means. . In order to detect the operation of the post-processing unit by the sheet discharging / conveying unit, for example, a post-processing operation command signal from the image forming unit to the post-processing unit is distributed and input to the sheet discharging / conveying unit. Good.

It should be noted that the shortest sheet ejection path is the sheet that is conveyed from the image forming section to the sheet ejecting section without changing its conveying direction when the sheet conveying path from the image forming section to the sheet ejecting section is viewed. This is a path that is assumed by extracting only possible paths. For example, if there is a path for the paper to reciprocate between the image forming unit and the paper discharge unit, the paper discharge excluding that part The route corresponds to that.

The sheet conveying means may be any one capable of holding the sheet carried in from the image forming section side and sending the sheet to the sheet discharging section side, for example, via the shortest sheet discharging path. There are a pair of conveyance rollers arranged in pressure contact with each other, a conveyance belt for adsorbing and conveying a sheet, and the like.
In general, the amount of paper fed is proportional to the amount of movement of the conveying surface of the conveying roller or the conveying belt, and the conveying speed of the sheet is proportional to the peripheral speed of the conveying roller or the conveying belt.

The sheet transport control means may be any means capable of controlling the sheet transport means. For example, when the sheet transport means is composed of the pair of transport rollers, a drive motor for driving the transport rollers to rotate. It can be configured with a control circuit to which the above-mentioned post-processing operation command signal is input and which controls the rotation of the drive motor. In the configuration, when the post-processing operation command signal is input, the control circuit temporarily stops the rotation of the drive motor, or the control circuit slows the rotation speed of the drive motor. It is possible to slow down the transport speed of the paper by the transport rollers, and consequently to extend the paper transport time.

By the way, in the present invention, when the post-processing means performs post-processing, the above-mentioned paper discharge / conveyance section is not limited to one that lengthens the conveyance time of the next paper only. It may also be possible to lengthen the transportation time of the sheet transported later. When the conveyance time of N sheets is lengthened, the interval between the pair of sheets discharged before and after the post-processing is defined as X when the interval between the two sheets caused by the operation cycle of the image forming unit is X. Maximum {(N +
1) × X}.

However, in order to lengthen the transport time of a plurality of sheets, it is necessary to hold the plurality of sheets in the sheet discharging and transporting section. Therefore, for example, the shortest sheet discharge path between the image forming section and the sheet discharge section is set to one straight line,
Moreover, as is clear when a plurality of sheet conveying means are arranged along the line to configure the sheet discharging and conveying section, the sheet discharging and conveying section becomes very large, and thus the image forming apparatus becomes very large. . Therefore, when a plurality of sheets are held in the sheet discharging / conveying unit, it is preferable to arrange a reversing conveying unit for reversing the sheet conveying direction so as to face the shortest sheet discharging path.

The reversing conveying means can be composed of, for example, a pair of conveying rollers which are arranged in pressure contact with each other and can rotate in forward and reverse directions. In the case where the reversing conveyance means is composed of a pair of conveyance rollers, the reversing conveyance means is opposed to the shortest sheet ejection path by arranging the two conveyance rollers along the shortest sheet ejection path, for example. Can be placed. The reversing conveyance means rotates the conveyance roller in the forward direction to temporarily draw in the sheet conveyed from the image forming section side, and then rotates the conveyance roller in the reverse direction to eject the sheet on the sheet ejection side. It may be operated so that it is discharged to.

In other words, by disposing the reversal conveying means so as to face the shortest sheet discharge path, it is not necessary to hold a plurality of sheets in the shortest sheet discharge path between the image forming section and the sheet discharge section. Since it is not necessary to secure the length of the shortest sheet discharge path from the image forming section to the sheet discharge section, the size of the image forming apparatus can be suppressed.

However, as the above-mentioned inversion conveying means, for example,
When a pair of transport rollers arranged in pressure contact with each other and capable of rotating in the forward and reverse directions is used, the reversal transport means must discharge the previously fed sheet before the next sheet is fed. Therefore, the pair of transport rollers need to eject the paper in a very short time after the paper is supplied, and must reversely rotate at a very high speed.

Therefore, when, for example, a pair of forward and reverse rotatable conveying rollers is used as the reverse conveying means, the pair of conveying rollers are arranged so as to be able to come into contact with and separate from each other, and the reverse conveying means and the sheet discharging section are arranged. It is advisable to provide a sheet conveying means in the shortest sheet discharge path between the pair of conveying rollers and separate the pair of conveying rollers when the sheet discharged from the pair of conveying rollers can be conveyed by the sheet conveying means. . Accordingly, even when the previous sheet remains between the pair of transport rollers, the next sheet can be carried in between the pair of transport rollers, that is, the leading edge of the next sheet is the pair of transport rollers. It is not necessary to rotate the pair of conveying rollers at a high speed so that the trailing edge of the preceding sheet is conveyed out between the pair of conveying rollers before being conveyed in between the pair of conveying rollers. It can be turned at low speed.

The state in which the sheet can be conveyed by the sheet conveying means means a state in which the sheet can be conveyed by the sheet conveying means itself, and, for example, a pair of conveying rollers arranged in pressure contact with each other is used for the sheet conveying means. When used as, means a state in which the pair of conveying rollers sandwich the sheet.

In the above image forming apparatus, when the post-processing means does not perform the post-processing, the paper is ejected to the paper ejecting portion at intervals according to the operation cycle of the image forming portion,
When the post-processing means performs the post-processing, the paper discharge / conveyance unit lengthens the conveyance time of the next paper, so that the next paper is ejected to the paper ejection unit with an interval wider than the above interval. .

As a result, in the image forming apparatus, the interval between the sheets before and after the post-processing by the post-processing means is wider than the interval between the sheets when the sheets are discharged according to the operation cycle of the image forming section. .

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is shown in FIG. The image forming apparatus of FIG. 1 is a copier that forms an image based on a document on a sheet, and includes an image forming unit 1 that reads the image of the document and forms an image on the sheet, and a large number of various sheets 3 One paper tray 2a, 2b, 2c and a discharge paper tray 3 in which a plurality of papers on which images have been formed are stacked.
And a sheet conveying section that sequentially conveys sheets from the sheet tray 2 to the discharged sheet tray 3 via the image forming section 1, and stapling processing and / or punching for a plurality of sheets stacked on the discharged sheet tray 3. Post-processing means 5 for processing
Have and. Further, these are divided into an image forming unit 100 having the image forming unit 1 and a post-processing unit 101 having a post-processing unit.

In the image forming apparatus, a paper carry-in / carrying path (broken line A → B) for carrying paper from each paper tray 2 to the image forming unit 1 and an image for forming an image on both sides of the paper. A paper circulation path (broken line of C → E → F → B) for conveying the paper discharged from the forming unit to the image forming unit again,
A sheet discharge path for conveying the image-formed sheet from the image forming section 1 to the discharge sheet tray 3 is set, and further, the sheet discharged from the image forming section changes its conveying direction in the sheet discharge path. Shortest paper discharge route (C
→ D) (broken line of D) and a sheet reversal discharge path (broken line of C → E → D) in which the conveyance direction of the sheet changes once are set.

The image forming section 1 includes an original reading means (not shown) for reading an image of an original, an image memory 1d for storing image information of the original, and a photosensitive drum rotatably arranged at a constant peripheral speed. 1a, a charging corotron 1b that uniformly charges the photosensitive drum 1a, and the image memory 1d.
Laser exposure means 1c for exposing the photosensitive drum 1a to form a latent image based on the image information in the inside, a developing unit 1e for adhering toner to the latent image to form a toner image, and the photosensitive drum 1a. And a pair of fixing rolls 1g that heat and pressurize the paper to fix the toner image as an image on the paper, and a transfer corotron 1f that applies a transfer voltage to the paper to transfer the toner image onto the paper. And an image forming control means 1h for forming an image on a sheet.

The paper carrying section includes a paper carrying-in carrying section arranged along the paper carrying-in carrying path, a paper paper circulating carrying section arranged along the paper circulating path, and a paper discharging path. And a sheet discharging and conveying section 4 arranged along the same.

In the present embodiment, the paper discharging / conveying section 4 includes four pairs of paper conveying rollers 4a, 4b, 4c, 4d which are sequentially arranged along the shortest paper discharging path.
A paper conveyance roller drive motor 4e that drives the four pairs of conveyance rollers, a discharge paper sensor 4f that optically detects the paper that has been carried in from the image forming unit 1, and a shortest paper discharge path that is the paper conveyance path. A first conveyance direction switching member 4g for switching between the (D direction) and the sheet reversal discharge path (E direction), and a pair of reversible conveyance that is arranged opposite to the shortest sheet discharge path and is capable of forward and reverse rotation. The roller 4h, a second transport direction switching member 4j that switches the transport route of the sheet discharged from the reverse transport roller 4h between the sheet circulation route (direction of F) and the sheet discharge route (direction of E), and the above-mentioned inversion. A reversing conveyance roller drive motor 4k that drives the conveyance roller 4h, a reversal conveyance roller clutch 4m that transmits the rotation of the reversal conveyance roller drive motor 4k to the reversal conveyance roller 4h, and the reversal. A reverse conveying roller retracting member 4p to separate the feed roller 4h, the image forming control unit 1h
And a paper ejection control means 4q for controlling them based on the information from the ejection paper sensor 4f. The pair of reversing conveyance rollers 4h are brought into pressure contact with each other via the sheet reversing discharge path (path E).

The reverse conveying roller clutch 4m
For example, as shown in FIG. 4, the rotation of the drive motor 4h is divided into forward rotation and reverse rotation by a gear, and the rotations are transmitted to the reversing roller 4h via the electromagnetic clutches 6a and 6b, respectively. Alternatively, as shown in FIG. 5, the rotation of the forward / reverse rotation drive motor 4k may be accelerated / decelerated by a gear and transmitted to the reversing roller 4h, but as shown in FIG. The rotation of the motor 4h is divided into forward rotation and reverse rotation by a gear, and one of them is divided into a torque limiter 6c.
And the other is transmitted to the reversing roller 4h via the electromagnetic clutch 4d, the number of control signals can be reduced, and it is not necessary to use an expensive drive motor capable of forward / reverse rotation, which is preferable. .

The reversing / conveying roller retract member 4q may be provided with an arm for holding the rotating shaft of one reversing / conveying roller 4h, and the arm may be moved by switching a solenoid.

The post-processing means 5 includes a post-processing member 5a having a stapler and a puncher arranged so as to sandwich a plurality of sheets stacked on the discharged sheet tray 3.
A post-processing sheet sensor 5b that optically detects the sheet discharged from the sheet discharge / conveyance unit 4, and an image forming control unit 1h.
And post-processing control means 5c for controlling the post-processing member 5a based on the information from the post-processing sheet sensor 5b.

Further, as shown in FIG. 2, the information transmitted from the image forming control means 1h to the paper discharge control means 4q includes a partial copy number signal for notifying a partial copy number,
A copy number signal indicating the number of copies to be continuously formed, and
There is a mode signal for notifying the set operation mode, and the information transmitted from the image forming control means 1h to the post-processing control means 5c includes a partial number signal for notifying the number of partial sheets and a set number of signals. There is a mode signal that indicates the operating mode.

In the image forming apparatus, the copy number signal has copy number information set on a panel (not shown) of the image forming unit 100, and the partial copy number signal is the number of originals read by the original reading means. Have information.

The operation modes include a staple mode for stapling the entire sheet, a punching mode for punching holes in the sheet, and a sheet ejected from the image forming section 1 again through the sheet circulation path for the image. Forming part 1
There is a double-sided image forming mode for carrying in the sheet, and the mode signal transmits the operation mode information to the sheet discharging and conveying section 4 and the post-processing section 5.

The operation of the sheet discharging / conveying section 4 and the post-processing means 5 in each operation mode will be described below.

In the staple mode, first,
The sheet discharging control unit 4q sets the first conveying direction switching member 4g and the second conveying direction switching member 4j so that the sheet can be discharged through the sheet reverse discharging path, and operates the sheet conveying roller drive motor 4e. .

Next, as shown in FIG. 6, when the discharge paper sensor 4f detects the paper carried in from the image forming section 1, the paper discharge control means 4q drives the reverse conveyance roller after a predetermined time. The motor 4k is operated to rotate the reverse conveyance roller 4h in the forward direction so that the reverse conveyance roller 4h draws the paper. Further, the sheet discharging control unit 4q rotates the reverse conveying roller 4h in the reverse direction by operating the reverse conveying roller clutch 4m, and discharges the sheet from the reverse conveying roller 4h.

After that, the paper is conveyed by three pairs of paper conveying rollers 4.
After passing through b, 4c and 4d, the sheet is discharged onto the discharged sheet tray 3 and the post-processing control means 5 operates the stapler when the post-processing sheet sensor 5b detects the same number of sheets as the partial number signal. The predetermined number of sheets are stapled. Then, in the image forming apparatus, the above operation is repeated for a predetermined number of copies, and a series of operations is ended.

By the way, the paper discharge control means 4q
When the number-of-copies signal is 2 or more and the same number of sheets as the partial number-of-sheets signal is detected by the discharge sheet sensor 4f, the next sheet is controlled by the control sequence shown in FIG. In the control sequence, the paper discharge control unit 4q once stops the reverse conveyance roller drive motor 4k when the reverse conveyance roller 4h draws the paper, and again operates the reverse conveyance roller drive motor 4k after a predetermined waiting time. At the same time, the reverse conveyance roller clutch 4m is operated to eject the sheet from the reverse conveyance roller 4h.

As a result, the image forming apparatus shown in FIG.
As shown in the detection signal of the post-processing sheet sensor 5b in FIG. 7, the timing at which the sheet is ejected to the ejection sheet tray 3 can be delayed, so that the interval between the sheets before and after the post-processing unit 5 performs the post-processing. Can be made wide enough for the post-processing means 5 to perform the stapling process, and the stapling process can be completed during the time interval.

In the case of executing the control sequence shown in FIG. 7, the paper discharge control means 4q reverses the second paper while discharging the first paper after the second copy. Since the sheet is carried into the carrying roller 4h, the reverse carrying roller retract member 4p is operated after a predetermined time from the start of carrying out the first sheet to separate the pair of reverse carrying rollers 4h. The predetermined time is from the timing when the leading edge of the first sheet in the transport direction is nipped by the second pair of sheet transport rollers 4b, and the leading edge of the second sheet in the transport direction is the reverse transport roller. It is set so that the pair of reversing conveyance rollers are separated by the timing of being pinched by 4h.

As a result, in the image forming apparatus, even when the first sheet remains between the pair of reverse conveying rollers 4h, the second sheet remains between the pair of reverse conveying rollers 4h. It can be carried in, and there is no inconvenience in conveying the paper.

Further, the paper discharge control means 4q activates the reverse transfer roller retract member 4p and the reverse transfer roller clutch 4m as soon as the first sheet is completely discharged from between the pair of reverse transfer rollers 4h. I tried to stop it.

As a result, in the above-mentioned image forming apparatus, the second sheet already drawn between the pair of reverse conveying rollers can be surely drawn in by a predetermined amount, and the subsequent operation is performed as usual. be able to.

In the punching mode, the sheet discharging / conveying section 4 and the post-processing means 5 operate similarly to the staple mode except that the puncher operates instead of the stapler.

In the double-sided image forming mode, first, the paper ejection control means 4q and the first conveying direction switching member 4g and the second paper feeding direction switching member 4g so that the paper can be supplied again to the image forming section 1 through the paper circulation path. The second conveyance direction switching member 4j is set and the paper conveyance roller drive motor 4e is operated. Next, the paper ejection control means 4q
When the discharge paper sensor 4f detects the paper carried in from the image forming unit 1, the reverse conveyance roller drive motor 4k operates after a predetermined time to rotate the reverse conveyance roller 4h in the forward direction, and the reverse conveyance roller 4h. Pull the paper into.
In addition, the sheet discharging control unit 4q switches the second transport direction switching member 4j and operates the reverse transport roller clutch 4m to rotate the reverse transport roller 4h in the reverse direction, thereby circulating the sheet from the reverse transport roller 4h. Eject the paper in the path.

As a result, in the above-mentioned image forming apparatus, by re-conveying the sheet to the image forming section 1 while reversing the conveying direction thereof, the sheet can be turned over to the image forming section 1 and conveyed again. An image can be formed on each.

[0049]

As described above, in the image forming apparatus of the present invention, when the post-processing means carries out the post-processing, the paper-discharging / conveying section lengthens the time for carrying the next paper so that the post-processing means Since the interval between the sheets before and after the post-processing is made wider than the interval between the sheets when the sheets are ejected according to the operation cycle of the image forming unit, that is, the sheet ejected before and after the post-processing is performed by the post-processing unit. Since the interval is made wider than usual, the above-mentioned post-processing can be completed in the meantime.

Therefore, in the above-mentioned image forming apparatus, the post-processing can be carried out without making the image forming means idle once, so that even if the image forming means having a high process speed is used, its ability can be sufficiently exhibited. Can be made.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the invention.

FIG. 2 is an explanatory diagram of a control system in the image forming apparatus of FIG.

FIG. 3 shows an example (1) of a reversing drive roller clutch.

FIG. 4 shows an example of a reversing drive roller clutch (2).

FIG. 5 shows an example of a reversing drive roller clutch (3).

6 is a control sequence (No. 1) of the reverse driving roller in the image forming apparatus of FIG.

7 is a control sequence (No. 2) of the reverse driving roller in the image forming apparatus of FIG.

[Explanation of symbols]

1: image forming unit, 3: discharged paper tray, 4: paper discharging and conveying unit, 5: post-processing means, (C → D path): shortest paper discharging path, 4a, 4b, 4c, 4d: paper conveying means, Four
h: reverse conveying means, 4k: reverse conveying roller drive motor,
4m: reverse conveyance roller clutch, 4p: reverse conveyance roller retract member, 4q: paper ejection control means.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65H 29/20 B65H 37/04 G03G 15/00 534

Claims (2)

(57) [Claims] 1. An image forming section for forming an image on a sheet, a sheet discharging section for discharging the sheet, a sheet discharging and conveying section for conveying the sheet from the image forming section to the sheet discharging section, and a sheet for the sheet discharging section. In the image forming apparatus having a post-processing unit that performs post-processing, the paper discharge transport unit includes the image forming unit and the paper discharge unit.
The shortest sheet ejection process that is provided between the
And the shortest paper discharge path,
Consists of a pair of rotatable transport rollers that control the transport direction of paper.
And a paper reversal discharge path having a reversal conveyance means for reversing
And the paper discharge / transport unit has two or more sets of the post-processing means.
When performing the above post-processing, add the first sheet of the following
The conveyance from the shortest paper discharge path to the paper reverse discharge path
After pulling in by the normal rotation of the roller, stop it temporarily, and then
After a certain waiting time, the reverse rotation of the transport roller
An image forming apparatus characterized in that the sheet is ejected from a paper reversal ejection path to lengthen the transport time of the first sheet. 2. The pair of discharge rollers are arranged so that they can come into contact with and separate from each other.
In addition, the first sheet of the next part is transferred by the transport roller.
While the paper is being ejected, the second sheet of paper
When it is loaded into the transfer discharge path, the first sheet concerned
At the timing when it can be transported by the transport means
The image forming apparatus according to claim 1, wherein the conveying rollers are separated from each other .