JPH0687297A - Sheet transport mechanism of image formation device - Google Patents

Abstract

PURPOSE:To transport a sheet stably without qualitative deterioration of an image and a paper jam in a transport path. CONSTITUTION:This sheet transport mechanism consists of a cutter guide 30, arranged at the inlet side of a cutter unit 50, which is connected to a transport motor of a transport roller mechanism 40 through a single directional clutch. Under this constitution, the cutter guide moves vertically in compliance with the rotating direction of the transport motor. In addition, when transporting a recording sheet 10 to the cutter unit 50, the cutter guide 30 is positioned below, thus forming a transport path for the recording sheet 100. On the other hand, when cutting the recording sheet 100 width-wise on the cutter unit 50, the cutter guide 30 is upheld to a position above as shown at 30b and thereby, an open space for forming a loop of the recording sheet 100 is constituted.

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 color electrostatic plotter, and more particularly to a sheet conveying mechanism for an image forming apparatus using a roll-shaped recording sheet as a recording sheet.

[0002]

2. Description of the Related Art In an image forming apparatus such as a color electrostatic plotter, roll paper has been widely used as recording paper. In this type of device, the image-formed part of the roll paper is separated from the unused part where the image is not formed, or the necessary part of the image-formed part is separated from unnecessary parts such as margins. In general, a sheet cutting device is provided. The sheet cutting device includes, for example, a Y cutter that cuts the roll paper in its width direction (Y direction) and an X cutter that cuts the roll paper in its conveyance direction (X direction), and these cutters are in an image formation state. The roll paper is cut by being selectively driven according to the above.

By the way, in an image forming apparatus equipped with such a sheet cutting device, it takes about 0.5 to 1 second to cut the entire width of the roll paper. Therefore, the conveyance of the roll paper in the sheet cutting device must be stopped while the cutting operation is being performed. However, even during the period in which the cutting is performed, the image is formed in the image forming apparatus, and thus the roll paper is continuously conveyed from the image forming apparatus to the sheet cutting apparatus. Therefore, generally, an open space for forming a loop of the roll paper is provided on the sheet carry-in side of the sheet cutting device.

[0004]

However, since the roll paper is generally thin, the roll paper has a property that a curl or the like is likely to occur at the leading end due to temperature or humidity. This tendency is particularly strong in electrostatic recording paper used in color electrostatic plotters. When the roll paper having such a property is fed into the open space, since the habit of the roll paper is not suppressed and corrected in the open space, the leading end of the roll paper is curled or bent due to the habit, and the roll paper becomes a sheet. Paper could get jammed without being loaded into the cutting device.

Further, it has been considered to eliminate the open space in order to prevent this problem. However, for that purpose, the conveyance of the roll paper in the image forming section must be stopped during the cutting period of the roll paper. In this case, the density of the image formed on the roll paper becomes non-uniform, which causes another problem that the image quality is deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to stably convey a sheet without causing image quality deterioration and causing a paper jam in the conveying path. It is to provide a sheet conveying mechanism of an image forming apparatus capable of performing the above.

[0007]

In order to achieve the above object, the present invention conveys a roll-shaped recording sheet to an image forming means to form an image, and then rolls the roll-shaped recording sheet on which the image is formed. In a sheet conveying mechanism of an image forming apparatus having at least a function of conveying and cutting to a cutting unit, a guide space for a roll-shaped recording sheet can be changed in a recording sheet conveying path between the image forming unit and the sheet cutting unit. A guide member for the roll-shaped recording sheet having the above-mentioned structure is disposed, and a control means for the guide member is provided. Then, the guide drive control means sets the guide space of the guide member to a predetermined first state suitable for sheet conveyance while the sheet cutting means is not cutting the rolled recording sheet. Further, the guide space of the guide member is set to the second state, which is larger than the first state, while the roll recording sheet is being cut by the sheet cutting means. is there.

[0008]

As a result, according to the present invention, the guide space of the guide member is in the relatively narrow first state suitable for sheet conveyance while the roll cutting sheet is not being cut by the sheet cutting means. Is set. Therefore, even if the leading end of the roll-shaped recording sheet has a curl or the like,
This tendency is corrected by the guide member, whereby the roll-shaped recording sheet is stably conveyed to the sheet cutting means without causing paper jam. On the other hand, while the sheet cutting device is performing the cutting operation, the guide space of the guide member is expanded to the second state, which is larger than the first state. That is, an open space is formed in the sheet conveying path between the image forming unit and the sheet cutting unit. Therefore, the roll-shaped recording sheet conveyed from the image forming means forms a loop in the guide space of the guide means. Therefore, it is not necessary to stop the conveyance of the roll-shaped recording sheet in the image forming unit during the sheet cutting operation, which prevents image quality deterioration.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration of a color electrostatic plotter having a sheet conveying mechanism according to the present invention.

In FIG. 1, reference numeral 4 denotes a recording paper roll in which an electrostatic recording paper is wound around a paper tube, and the recording paper 100 rewound from the recording paper roll 4 is provided on an encoder roller 5 and an encoder pinch roller 5e. Hold the electrostatic head 1
Be transported to. The encoder roller 5 is the recording paper 10 described above.
It has a function of transporting 0 and a function of detecting the transport speed of the recording paper 100 from the number of rotations. A pad roller 2 is arranged opposite to the head surface of the electrostatic head 1, and the recording paper 100 is pressed against the head surface of the electrostatic head 1 by the pad roller 2. Then, in this state, the electrostatic head 1 forms an electrostatic latent image on the recording paper 100 in accordance with an image signal transferred from an information processing device (not shown). A position sensor 3 is arranged in the conveying path between the encoder roller 5 and the electrostatic head 1, and the position sensor 3 detects the position of the recording paper 100 with respect to the electrostatic head 1.

The recording paper 100 on which the electrostatic latent image is formed in the electrostatic head 1 is conveyed to the developing head portion 6l after the static elimination brush 21 removes unnecessary static electricity in the portion where the latent image is not formed. . The developing head unit 6 is provided with four developing heads corresponding to the developing colors of black, cyan, magenta and yellow. And
Wet toner is supplied to the latent image forming surface of the recording paper 100 by these developing heads, respectively, whereby color development of the electrostatic latent image is performed. The developing head section 6
The recording paper 100, which has been developed in, is held by the suction roller 8 and the conveyor belt 15,
It is conveyed to the nip point A between the drive roller 9 and the drive pinch roller 12. In this conveying process, the suction roller 8
Then, the excess wet toner remaining on the recording paper 100 is absorbed. Reference numeral 17 is a guide for guiding the recording paper 100 to the nip point A. The recording paper 100 conveyed to the nip point A is nipped by the drive roller 9 and the drive pinch roller 12, and thus guided to the take-up roller 10 during the development process, and cuts after the development process. It is conveyed to the unit 50. The switching of the transport path is performed by the transport path switching gate 11. The take-up roller 10 holds the recording paper 100 between the take-up pinch roller 13 and the take-up roller 10 to take up the recording paper 100 in the middle of development and temporarily store it. Further, a paper path sensor 14 is arranged in the conveyance path between the nip point A and the winding roller 10. This paper path sensor 14
Detects the presence of the recording paper 100.

By the way, the cutter unit 50 is constructed as follows. That is, the cutter unit 50
A paper feed roller mechanism 40 for carrying the recording paper 100 into the cutter unit 50 is provided in each of the frames 51a and 51b.
And a Y cutter unit 52 for cutting the recording paper 100 in a direction orthogonal to the transport direction, that is, a width direction of the recording paper 100, and an X cutter unit 53 for cutting the recording paper 100 in the transport direction. Has been done.

First, the Y-cutter unit 52 is used for the recording paper 10.
Round blade 52a that moves at high speed in the width direction of 0, and this round blade 5
It has a fixed blade 52b that is in sliding contact with 2a. And
Recording paper 10 supplied by the paper feed roller mechanism 40
0 is sandwiched between these round blades 52a and fixed blades 52b and cut in the width direction.

The X cutter unit 53 has a plurality of X cutters arranged at predetermined intervals in the width direction of the recording paper 100. Each X cutter has a round blade that is rotationally driven at a high speed by a cutter motor (not shown), and cuts the recording paper 100 in the conveyance direction by the round blade. In addition, 53a is a discharge roller driven by a pulse motor (not shown),
53b is a paper discharge pinch roller, and the recording paper 100 cut by the round blade is these rollers 53a, 53b.
It is held by and is discharged to the stocker 22.

The paper feed roller mechanism 40 has a paper feed roller 41 and a paper feed pinch roller 42 for pressing the recording paper 100 against the paper feed roller 41. And
These rollers 41 and 42 hold the recording paper 100 (not shown) conveyed from the upstream side of the conveyance path and supply it to the Y cutter unit 52 and the X cutter unit 53 in order. A cutter guide 30 is attached to the paper feed roller mechanism 40. The cutter guide 30 is arranged so as to project toward the entrance side of the cutter unit 50, and moves up and down by the rotation operation of the carry motor 34 that operates according to an instruction from the control circuit 60.

FIG. 2 is an enlarged front sectional view showing the construction of the main part of the paper feed roller mechanism 40. In the figure,
Reference numeral 34 is a conveyance motor composed of a pulse motor, and the conveyance motor 34 is fixed to the frame 51a of the cutter unit by studs 35. The drive shaft 34 a of the carry motor 34 has a first unidirectional clutch 43.
Also, the second one-way clutch 31 is axially mounted. A paper feed roller shaft 44 is fixed to the first one-way clutch 43, and the paper feed roller 41 is fixed to the paper feed roller shaft 44. First one-way clutch 43
Transmits the driving force of the carry motor 34 to the paper feed roller 41 via the paper feed roller shaft 44 when the carry motor 34 rotates in the normal direction according to the instruction of the control circuit 60. Carry it inside. On the other hand, a cutter guide 30 is supported by the second one-way clutch 31 via an arm 32. The second one-way clutch 31 transmits the driving force of the carry motor 34 to the cutter guide 30 via the arm 32 when the carry motor 34 rotates in the reverse direction in accordance with the instruction of the control circuit 60, and thereby the cutter guide 30. Lift the guide 30. Incidentally, 33 is a bearing for supporting the drive shaft 34a of the carry motor 34 on the frame 51a.

Next, the recording sheet conveying operation of the apparatus configured as described above will be described according to the control procedure of the control circuit 60. In the recording standby state, the leading edge of the recording paper 100 unwound from the recording paper roll 4 is held at the nip point A by the drive roller 9 and the drive pinch roller 12. When an image signal is sent from an external information processing device in this state, the driving roller 9 causes the recording paper 100
The transportation of is started. Then, the electrostatic head 1 forms a latent image on the recording paper 100 according to the image signal, and the developing head 6 develops the latent image.
In the case of a monochrome image, the recording sheet 100 on which the image is formed by this development is conveyed to the cutter unit 50 as it is because the conveyance path switching gate 11 is in the state shown by 11b in FIG. On the other hand, in the case of a color image, since the transport path switching gate 11 is in the state shown by 11a in FIG. 1, the recording paper 100 on which the first color has been developed is taken up by the take-up roller 10. It is temporarily stored. Then, when the development of the first color is completed, the recording paper 1
00 is conveyed in the opposite direction by the drive roller 9, whereby the tip end portion is returned to the position of the nip point A. And
From this state, the recording paper 100 is again conveyed in the forward direction, and the electrostatic head 1 and the developing head 6 respectively form a latent image of the second color and develop the latent image. Thereafter, the image formation of the third color and the fourth color is similarly performed by repeating the operations of the first color and the first color.

When the image formation is completed in this way, the control circuit 60 shifts from step 3a to step 3b as shown in FIG. 3, in which the transport path switching gate 11 is brought to the state shown by 11a in FIG. Switch. Therefore, the recording paper 100 on which the image has been formed is conveyed toward the cutter unit 50. Further, at this time, the control circuit 60 issues a drive instruction to the transport motor 34 of the paper feed roller mechanism 40 in the cutter unit 50 to rotate the paper feed roller 41 in the normal direction in step 3c. Therefore, the paper feed roller 41
Is conveyed by the first one-way clutch 43.
Since the driving force is transmitted, the forward rotation operation is started. Further, the forward rotation of the carry motor 34 releases the urging force to the cutter guide 30. As a result, the cutter guide 30 descends downward and is set to the state indicated by 30 in FIG. That is, a narrow transport path suitable for transporting the recording paper 100 is formed. Therefore, the recording paper 100
Even if the tip has a curl, it is guided by the cutter guide 30 and is stably conveyed to the cutter unit 5 without causing a paper jam.

Since there is generally an unnecessary portion on the leading end of the recording paper 100 where an image is not formed, it is necessary to cut this unnecessary portion in the cutter unit 50. Therefore, the control circuit 60 executes the control for cutting off the unnecessary portion as follows. That is, when the boundary position between the unnecessary portion of the recording paper 100 and the image forming portion reaches the position of the Y cutter 52 by the conveyance of the paper feed roller 41, the control circuit 60 first causes the conveyance motor 34 to rotate normally in step 3d. After stopping the operation, reverse rotation is performed for 30 pulses. Then, the first one-way clutch 4
By the action of 3, the transmission of the driving force from the carry motor 34 to the paper feed roller 41 is cut off, and the rotation of the carry roller 34 is stopped. On the contrary, the conveyance motor 34
The reverse rotation driving force is transmitted to the arm 32 via the second one-way clutch 31, so that the cutter guide 30 is lifted upward. Therefore, the cutter guide 30 is in the state shown by 100b in FIG. 1, and thereby an open space is formed at the entrance side of the cutter unit 50.

When the above cutting preparation is completed, the control circuit 60
Continues to step 3e where the transport motor 3
4 is stopped for a certain period. During this stop period, the Y cutter 5
2 is set to a time slightly longer than the time required to cut the entire width of the recording paper 100, for example, 0.6 seconds.
Then, when the carry motor 34 is stopped, the control circuit 60
Simultaneously drives the Y cutter 52. Therefore, the unnecessary portion of the recording paper 100 is cut by the Y cutter 52, and the cut unnecessary portion is discharged by the discharge roller 53 b of the X cutter 53. During the cutting period of the recording paper 100 by the Y cutter 52, as described above, the transport motor 34
Has stopped spinning. Therefore, the lifted state of the cutter guide 30 is maintained. Therefore, even when the recording paper 100 is continuously fed from the driving roller 9 during the cutting period of the recording paper 100 by the Y cutter 52, the recording paper 100 is accumulated in a loop in the open space formed by the cutter guide 30b. To be done.

When the cutting of the unnecessary portion of the leading end of the recording paper 100 is completed in this way, the control circuit 60 causes the recording paper 10 to move next.
The control for cutting the image forming portion of 0 by the X cutter 53 in the transport direction is executed. That is, the control circuit 60 proceeds to step 3f to restart the forward rotation of the carry motor 34, and at the same time supplies the X cutter 53 with a cutting instruction. Therefore, the image forming portion of the recording paper 100 is conveyed to the X cutter 53, and is cut in the conveying direction by the X cutter 53. When the forward rotation of the carry motor 34 is resumed, the bias by the carry motor 34 is released, and the cutter guide 30a is gradually lowered by its own weight to the position indicated by 30 in FIG.

When the cutting by the X cutter 53 is completed,
The end position of the image forming portion of the recording paper 100 is the Y cutter 52.
When the cutting position is reached by the control circuit 60,
The carry motor 34 is rotated reversely by 30 pulses by g.
Therefore, the cutter guide 30 is lifted to the position indicated by 30b in FIG. 1, thereby forming an open space for forming a loop of the recording paper 100. And
The control circuit 60 controls the conveyance roller 34 to 0.
It is stopped for 6 seconds, and the Y-cutter 52 is driven during this time to cut the recording paper 100 in the width direction. The cut recording paper 100 on which the image has been formed is carried out to the stocker 22 by the paper discharge roller 53b. Also, after this disconnection, the control circuit 6
At 0, the conveyance motor 34 and the drive motor 9 are reversely rotated until the recording paper 100 is no longer detected by the paper path sensor 14 in step 3i. Therefore, the unused recording paper 100 left on the conveyance path due to the cutting by the Y cutter 52 is the drive roller 9 and the drive pinch roller 12.
It is pulled back until the tip portion returns to the nip point A between and. Then, the control circuit 60 finally stops the paper discharge roller 53b in step 3j, and thereafter returns to the standby state for forming the next image.

Thus, in this embodiment, the cutter unit 5
The cutter guide 30 is disposed on the inlet side of 0, and the cutter guide 30 is connected to the conveyance motor 34 of the conveyance roller mechanism 40 via a one-way clutch to move up and down in accordance with the rotation direction of the conveyance motor 34. It is configured to do. When the recording paper 100 is conveyed to the cutter unit 50, the cutter guide 30 is positioned below to form a conveyance path for the recording paper 100, while the cutter unit 50 cuts the recording paper 100 in the width direction. At times, the cutter guide 30 is lifted to the upper position shown by 30b, thereby forming an open space for forming a loop of the recording paper 100.

Therefore, in this embodiment, the recording paper 10
When 0 is conveyed to the cutter unit 50, the recording paper 10
0 is reliably guided and transported by a relatively narrow transport path formed by the cutter guide 30. Therefore, even if the leading edge of the recording paper 100 has a curl or the like, this habit is corrected by the narrow conveyance path, and thus the recording paper 1
00 is stably supplied to the cutter unit 50 without causing a paper jam. On the other hand, when the conveyance of the recording paper 50 is stopped in the cutter unit 50 and the recording paper 100 is cut in the width direction, the recording paper 100 continuously fed by the drive roller 9 is constituted by the cutter guide 30b. It accumulates in a loop in the open space. Therefore, it is not necessary to stop the conveyance of the recording paper 100 by the driving roller 9 during the cutting period of the recording paper 100.
As a result, there is no concern that a difference in the density of the developed color will occur in the developing head 6, and this can prevent image quality deterioration. Further, in this embodiment, since the cutter guide 30 is moved up and down by changing the rotation direction of the conveyance motor 34, it is not necessary to provide a drive mechanism including a motor for moving the cutter guide 30 up and down. It can be realized with a relatively simple configuration.

The present invention is not limited to the above-mentioned embodiment, and for example, the configuration and shape of the guide member, the configuration of the mechanism for changing the guide space formed by this guide member, the control procedure, etc. Various modifications can be made without departing from the paper of the present invention.

[0026]

As described above in detail, according to the present invention, the roll-shaped recording sheet is configured so that the guide space for the roll-shaped recording sheet is variable in the recording sheet conveying path between the image forming means and the sheet cutting means. And a control means for controlling the guide member. Then, the guide drive control means sets the guide space of the guide member to a predetermined first state suitable for sheet conveyance while the sheet cutting means is not cutting the rolled recording sheet. Further, the guide space of the guide member is set to the second state, which is larger than the first state, while the roll recording sheet is being cut by the sheet cutting means.

Therefore, according to the present invention, it is possible to provide a sheet conveying mechanism of an image forming apparatus which can stably convey a sheet without causing image quality deterioration and causing paper jam in the conveying path. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color electrostatic plotter including a sheet conveying mechanism according to an embodiment of the present invention.

FIG. 2 is a front cross-sectional view showing the configuration of the main parts of the transport roller mechanism shown in FIG.

3 is a flowchart showing a control procedure and control contents by the control circuit shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrostatic head 2 ... Pad roller 3 ... Position sensor 4 ... Recording paper roll 5 ... Encoder roller 5e ... Encoder pinch roller 6 ... Development head 8 ... Suction roller 9 ... Drive roller 10 ... Winding roller 11 ... Transport path switching gate 12 ... Drive pinch roller 13 ... Take-up pinch roller 14 ... Paper path sensor 15 ... Conveying belt 17, 19 ... Guide 21 ... Eliminating brush 22 ... Stocker 30, 30b ... Cutter guide 31 ... Second one-way clutch 32 ... Arm 33 bearing 34 ... conveyance motor 34a ... drive shaft 35 ... stud 40 ... paper feed roller conveyance mechanism 41 ... paper feed roller 42 ... paper feed pinch roller 43 ... first one-way clutch 44 ... paper feed roller shaft 50 ... cutter unit 51a, 51b ...
Frame 52 ... Y cutter 52a ... Round blade 52b ... Fixed blade 53 ... X cutter 53a ... Paper ejection roller 53b ... Paper ejection pinch roller 60 ... Control circuit 100, 100a
…Recording paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/00 111 7369-2H

Claims (2)

[Claims] 1. An image forming apparatus having at least a function of transporting a roll-shaped recording sheet to an image forming unit to form an image, and then transporting the roll-shaped recording sheet on which the image is formed to a sheet cutting unit to cut the sheet. In a sheet conveying mechanism provided in the apparatus, the roll recording sheet is provided in a recording sheet conveying path between the image forming unit and the sheet cutting unit to guide the roll recording sheet to the sheet cutting unit. A guide member in which the guide space for the sheet is variable, and the guide space of the guide member is set to a predetermined first state during a period in which the roll cutting sheet is not cut by the sheet cutting means. And during the period when the roll recording sheet is being cut by the sheet cutting means, the guide space of the guide member is Sheet conveying mechanism of the image forming apparatus, wherein a scan to and a guide driving control means for variably setting the second state greater than said first state. 2. The sheet cutting means has a cutting signal generating means for generating a cutting signal for instructing cutting of the roll-shaped recording sheet, and the guide drive control means cuts the cutting signal generated from the cutting signal generating means. The sheet conveying mechanism of the image forming apparatus according to claim 1, wherein the guide member is driven based on a signal.