JP2515441B2 - 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 that feeds transfer sheets in parallel, feeds them to registration rollers, and further conveys them toward an image forming unit.

[0002]

2. Description of the Related Art Conventionally, transfer sheets such as envelopes are fed in parallel by a feed roller, for example, two sheets are fed in parallel and fed to a registration roller to be in a nip state. There is known an image forming apparatus that simultaneously transfers an image to the transfer paper. In such an image forming apparatus, the transfer paper is conveyed from the paper feed cassette to the registration rollers at the same timing on the left and right by the feed roller.

[0003]

In such an image forming apparatus, one of the left and right transfer sheets is continuously fed,
Or, if the transfer paper is fed while the transfer paper is in front of the paper feed cassette due to double feed,
The transfer sheet on the front side of the paper feed cassette comes into contact with the registration roller first. In such a case, after the transfer sheet comes into contact with the registration roller, the feed roller continues feeding the transfer sheet until the other transfer sheet comes into contact with the registration roller. The bending of the transfer paper that comes into contact with the transfer paper is increased, and the transfer paper is wrinkled or folded, and particularly in the case of an envelope, the transfer paper vibrates to cause a squeal.

As a countermeasure against this, it is conceivable to configure a paper feed mechanism for controlling the left and right transfer papers to be independently fed, but the structure becomes complicated and the cost is increased.

An object of the present invention is to solve the above problems, and an object thereof is to provide an image forming apparatus which prevents the transfer paper, which has previously come into contact with the registration rollers, from being folded during parallel feeding. To do.

[0006]

In order to achieve the above object, the present invention provides an image forming apparatus for guiding a transfer sheet, which is conveyed in parallel via a registration roller on a conveyance path, to an image forming section. The first and second roller portions which are arranged upstream of the conveyance path and at a position shorter than the length dimension of the transfer sheet to be conveyed, and which are juxtaposed with a shaft provided in a direction traversing the conveyance path. Between the registration roller and the feed roller and a feed roller provided with a torque limiter mechanism that idles when each of them is equal to or greater than a predetermined load torque, and corresponds to the arrangement of the first and second roller portions. First installed on the road to detect the arrival of transfer paper,
Second registration means, and the registration roller starts driving after a lapse of a predetermined time from the time when the detection signal is obtained later from the detection signals from the first and second detection means. Has been done.

According to the image forming apparatus having the above structure, the plurality of transfer sheets are fed in parallel by the first and second roller portions.
Then, among the transfer papers fed in parallel, the transfer paper which comes into contact with the registration roller first, that is, the transfer paper detected first by one of the first and second detecting means is the other transfer paper. Bends until it reaches the registration roller, but this bending causes a load torque of a predetermined torque or more to be applied to the roller portion, so that the roller portion idles and no further bending occurs, and the proper nip state is achieved. Is retained. Next, when the detection means detects the arrival of another transfer sheet at the registration roller, the registration roller is started to drive after a predetermined time, and both transfer sheets are aligned in parallel to the image forming unit with their leading ends aligned. Be transported.

[0008]

FIG. 2 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. The image forming apparatus includes paper feed cassettes 4a and 4b, paper feed rollers 5a and 5b, a feed roller pair 1, a registration switch 6, a registration roller pair 7, a photoconductor 8, a light emitting unit 9 including a laser, a polygon mirror 10, and a transfer unit. 11, a fixing unit 1 including a fixing roller and the like
2, discharge roller pairs 13 and 15, a discharge guide 14, a discharge tray 16 and the like.

Then, the light emitting section 9 emits light in response to an image signal input from the outside of the image forming apparatus, and the laser beam from the light emitting section 9 exposes the surface of the photoconductor 8 through the polygon mirror 10. On the other hand, the surface of the photoconductor 8 is charged by a charging device (not shown), exposed to form an electrostatic image, and developed by a developing device (not shown).

On the other hand, the transfer paper from the paper feed cassette 4a or the paper feed cassette 4b is fed by the feed roller 1 to, for example, 2
The sheets are fed in parallel in rows and come into contact with the registration roller pair 7, and the drive of the photoconductor 8 and the registration roller pair 7 is controlled based on a signal from the registration switch 6.

The developed image is transferred to the transfer section 11
After being transferred to each of the transfer papers by the fixing unit 12, it is fixed by the fixing unit 12, and the discharge guide 1 is discharged by the discharge roller pair 13, 15.
The sheet is discharged to the discharge tray 16 via 4.

Next, the structure of the feed roller 1 will be described. The feed roller 1 is composed of a forward rotation roller 2 and a reversal roller 3, and the transfer paper is separated and fed by these rollers 2 and 3. The forward rotation roller 2 is shown in FIG.
As shown in FIG. 3, the transfer is composed of the shaft 21 and the roller portions 22 and 23, and is rotated in the paper feeding direction (direction of arrow A in FIG. 2) and is set in advance in parallel from the paper feeding cassette 4a or the paper feeding cassette 4b. The paper is fed to the registration roller pair 7 in parallel. That is, the transfer paper on the left side is sent by the roller unit 22, and the transfer paper on the right side is sent by the roller unit 23.

Further, as shown in FIG. 3, the roller portions 22 and 23 are fixed portions 22a and 23a and idling portion 22, respectively.
A torque limiter mechanism composed of b and 23b is provided.
The fixing portions 22a and 23a are arranged on the inner diameter side of the idling portions 22b and 23b, and are fixed to the shaft 21 by screws 22c and 23c. The idling portions 22b and 23b have their peripheral surface portions formed of a rubber material or the like, and are configured to idly rotate with respect to the fixed portions 22a and 23a when a load torque of a predetermined torque or more is applied. That is, the idle parts 22b, 23
The b and the fixed portions 22a and 23a are made of, for example, a magnet and an iron piece, and these are connected by magnetic force. And
When a load torque equal to or higher than a predetermined torque is applied to the idling portions 22b and 23b, the idling portions 22b and 23b are made to idle.

The idle parts 22b and 23b and the fixed part 22
It is also possible to form a and 23a with a resin or the like and connect them by a frictional force. In addition, the idle parts 22b, 23
When a load torque equal to or greater than the spring force (predetermined torque) of the spring coil is applied to the fixed portion 22a and the fixed portion 22a, the spring coil is connected to the fixed portion 22a and the fixed portion 22b.
May be idle.

The reversing roller 3 has a shaft 3 as shown in FIG.
1 and the roller portion 3 facing the roller portions 22 and 23
2 and 33, which rotate in the opposite direction to the forward rotation roller 2 to prevent double feeding of transfer sheets.

The registration switch 6 is composed of registration switches 6a and 6b so that the left and right transfer sheets fed in parallel are independently detected. And
The registration roller pair 7 is driven when a predetermined time elapses after both the registration switches 6a and 6b are turned on.

Next, the operation of the feed roller 1 will be described with reference to the timing chart of FIG. When the paper feed roller 5a or the paper feed roller 5b is driven at time t1 to start the paper feed, the transfer paper is conveyed from the paper feed cassette 4a or the paper feed cassette 4b to the feed roller 1. At the same time, the driving of the feed roller 1 is started, and the transfer sheet is further fed in parallel toward the registration roller pair 7.

Then, for example, when the left transfer sheet reaches the registration switch 6a first (at time t2), the registration switch 6a is turned on, and then the left transfer sheet comes into contact with the registration roller pair 7. At this time, the feed roller 1
Continues to drive the right side transfer paper to the registration roller pair 7, the leading end of the left side transfer paper is the feed roller 1
As a result, the resist roller pair 7 is pressed and bent. Then, when a load torque of a predetermined torque or more is applied to the forward rotation roller 2 due to the reaction of the deflection, the forward rotation roller 2 starts idling and prevents the transfer sheet from being deflected more than a predetermined amount.

On the other hand, the transfer paper on the right side is the registration switch 6
When it reaches b (at time t3), the registration switch 6b
Turns on. After the registration switch 6b is turned on, when a preset time T1 has elapsed, that is, when the transfer paper on the right side comes into contact with the registration roller pair 7 and a sufficient amount of time elapses so that the transfer sheet slightly bends and enters the nip state. ,
The registration roller pair 7 is driven. That is, the left and right two rows of transfer papers are conveyed to the photoconductor 8 in a state where the front end timings thereof are matched, and the images are transferred to the respective transfer papers.

As described above, when the transfer rollers 1 feed the transfer sheets in parallel to the registration roller pair 7, if one transfer sheet is abutted against the registration roller pair 7 due to double feeding or the like, Even if the transfer paper contacting the registration roller pair 7 is excessively bent, a load torque of a predetermined torque or more is applied to the normal rotation roller 2 by the bending force, and the normal rotation roller 2 idles to transfer. It is possible to prevent excessive bending of the paper.

In the above description, the transfer sheets fed in parallel are two rows, but they may be three rows or more. In this case, the number of roller portions of the forward rotation roller 2 and the reversal roller 3 is increased according to the number of rows.

[0022]

According to the present invention, the first and second roller portions of the feed roller are constructed so as to idle at a predetermined load torque or more, and among the detection signals from the first and second detecting means, Since the registration rollers are configured to start driving after a lapse of a predetermined time from the time when the detection signal is obtained, at least one transfer paper among the transfer papers fed in parallel is first transferred to the registration roller by double feeding or the like. Even if the contact paper comes into contact with the transfer paper to cause excessive bending, it is possible to prevent the roller portion that feeds the transfer paper from idling and to cause the above-mentioned extra bending.
Therefore, it is possible to prevent the transfer paper from wrinkling, folding, squealing, and the like, and it is possible to convey the transfer papers in parallel to the image forming unit with the leading ends thereof aligned.

[Brief description of drawings]

FIG. 1 is a front view showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention.

FIG. 3 is a perspective view showing an example of a normal rotation roller.

FIG. 4 is a timing chart for explaining the operation of the feed roller.

[Explanation of symbols]

 1 Feed roller pair 2 Forward rotation roller 3 Reversal roller 7 Registration roller pair 21 Shaft 22,23 Roller section 22a, 23a Fixed section 22b, 23b Idling section

Continuation of the front page (56) References JP-A-59-217540 (JP, A) JP-A-63-147739 (JP, A) JP-A-59-108636 (JP, A) Actual development 63-175647 (JP , U) Actually open 60-85658 (JP, U) Actually open 3-73546 (JP, U)

Claims (1)

(57) [Claims] 1. A parallel arrangement via registration rollers on a conveying path.
The image forming apparatus that guides the transfer paper conveyed in a row to the image forming unit
The upstream side of the conveyance path with respect to the registration rollers, and
If the position is shorter than the length of the transfer paper
No. 1 installed side by side on a shaft provided in the direction crossing the transport path
Each of the first and second roller parts has a predetermined load torque or more.
Feed roller with torque limiter mechanism
Between the registration roller and the feed roller.
And a conveyance path corresponding to the arrangement of the first and second roller portions.
First, which is provided on the top and detects the arrival of the transfer paper,
A second detection unit, wherein the registration roller is
Of the detection signals from the first and second detection means, detected later
Driving starts after a lapse of a predetermined time from the time when the signal is obtained.
Imaging instrumentation, characterized in that is adapted to be
Place .