JP4032844B2 - Sheet conveying apparatus, image forming apparatus, and automatic document conveying apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus, an image forming apparatus, and an automatic document conveying apparatus, and more particularly to an improvement of a registration unit that controls sheet conveying timing and posture.
[0002]
[Prior art]
In image forming apparatuses and automatic document conveying apparatuses, generally, a registration unit is provided at a stage upstream of a transfer position, which is an image forming position, or before the image reading position. The attitude of the camera is controlled. With these controls, there is no image position shift in image formation, and an image with no image tilt is formed, and image data that similarly causes image position shift and image tilt in image reading is prevented. The
[0003]
The resist unit generally includes a loop forming unit and a resist unit, and after the leading edge of the sheet reaches the resist unit, a predetermined amount of the sheet is conveyed by the loop forming unit, thereby forming a sheet loop upstream of the resist unit. The leading edge position of the sheet is constant and uniformly controlled over the entire width of the sheet by the stiffness of the sheet. After the leading edge is controlled in this way, the registration unit is activated to convey the sheet, whereby the conveyance timing is accurately controlled and the sheet is conveyed without inclination.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional sheet conveying apparatus, since a loop is formed by conveying a predetermined amount of sheet after the leading edge of the sheet reaches the registration means, a loop having a constant amount or a constant height is always formed. . However, in order to accurately perform timing control and attitude control, it is necessary to change the loop amount depending on the paper quality. In other words, it is necessary to increase the loop amount for a strong sheet. If the loop amount is insufficient, variations in timing and posture will occur. On the contrary, the loop amount is the same as that for a strong sheet for a weak sheet. Doing so may cause the sheet to break or wrinkle.
[0005]
For this reason, the conventional sheet conveying apparatus has a problem that the timing, posture variation, paper breakage, wrinkles, and the like are likely to occur. In addition, there is a problem that the width of the fluctuation range allowed for setting the loop amount is narrow and difficult to set, and the stability is insufficient.
[0006]
The present invention solves the above-described problems in the conventional sheet conveying apparatus, and the sheet conveying apparatus, the image forming apparatus, and the automatic document conveying in which the sheet conveying timing and posture are correctly controlled without being influenced by the properties of the sheet to be conveyed. An object is to provide an apparatus.
[0007]
[Means for Solving the Problems]
The object of the present invention is achieved by the following invention.
[0008]
1. A linear a and the conveyance resistance lower conveying passage can be formed and a high conveyance resistance bent the conveying path of the movable transport path forming means,
Driving means for switching from the bent conveyance path to the linear conveyance path by driving the movable conveyance path forming means;
A driving roller and a driven roller for conveying the sheet in the conveying path , wherein the driving roller connects the conveying unit, the driving shaft , and the conveying unit and the driving shaft, and the driving force of the driving shaft is transmitted to the conveying unit; a loop forming means having a resilient transmission means for accumulating the driving force according to the load exerted on the conveyor section as well as transmission to,
Anda register means disposed downstream of said conveying path and said loop forming means,
After conveying the conveying path bent by the loop forming means, the sheet is switched to a linear conveying path to convey the sheet, and the driving force accumulated in the elastic transmission means is used to push the sheet against the resist means. A sheet conveying apparatus that forms a loop on the sheet by contact .
[0009]
2. It said drive means after the leading edge of the sheet is introduced into straight the conveyance path, described in 1, characterized by forming said transportation path bent by driving the movable feed path forming means Sheet transport device.
[0010]
3. Has a sensor located immediately upstream of said register means, said drive means, based on the leading edge detection signal by the sensor, the linear from the transport path bent by driving the movable feed path forming means 3. The sheet conveying apparatus according to 1 or 2, wherein the sheet conveying apparatus is switched to a conveying path.
[0011]
4). Image forming apparatus characterized by a sheet conveying apparatus according to any one of the 1 to 3 were used as the recording sheet feed means for feeding a sheet to the transfer position.
[0012]
5. An automatic document conveying device comprising the sheet conveying device according to any one of the above items 1 to 3.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A sheet conveying apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 are views showing a sheet conveying apparatus according to an embodiment of the present invention, FIG. 4 is a view showing a driving roller of a loop forming means, and FIG. It is a figure which shows the change of.
[0014]
The sheet conveying device includes a loop forming unit LP including a guide roller GR, a driving roller 101 and a driven roller 102, and a registration unit RR including a driving roller 103 and a driven roller 104.
[0015]
The drive roller 101 has a structure shown in FIG. In the example shown in FIG. 4A, the drive shaft 101c and the driven shaft 101b are connected by a spiral spring 101d as elastic transmission means. A rubber layer 101a that forms a conveyance unit that conveys the sheet P is integrally formed on the driven shaft 101b. Since the driving roller 101 has such a structure, the driving force of the driving shaft 101c driven by the motor 112 is not transmitted directly to the rubber layer 101a but is transmitted via the spiral spring 101d. Accordingly, when the drive shaft 101c rotates with a constant driving force, the twist angle of the spiral spring 101d varies depending on the load applied to the rubber layer 101a. FIG. 5 shows the angular relationship between the spiral spring fixing pin P2 provided on the drive shaft 101c and the spiral spring fixing pin P1 provided on the driven shaft 101b. As shown in the figure, when there is no load, for example, the angle between the spiral spring fixing pins P1 and P2 is 0, but when the load is light, the angle is θ1, and when the load is heavy, the angle θ2 is 0 <θ1 <θ2. And the driving force according to angle (theta) is accumulate | stored in the driven shaft 101b.
[0016]
In the example shown in FIG. 4B, the drive shaft 101c and the driven shaft 101b are connected by a plate-like or rod-like torsion spring 101e as an elastic transmission means.
[0017]
The driving roller 104 is driven by a motor 113, and the motor 113 is activated at a timing controlled based on a leading edge detection signal of the sensor 110, for example, and conveys a sheet.
[0018]
106 is a pair of fixed guides, 107 is a pair of movable guides as movable transport path forming means, 108 is a fixed loop upper guide formed in a mountain shape, and 109 is a linear and fixed lower loop guide.
[0019]
The movable guide 107 moves to a position where a mountain-shaped bent conveyance path is formed as shown in FIG. 2 and a position where a linear conveyance path is formed as shown in FIGS. Is done. 110 is a sensor that detects the leading edge of the sheet P, and 115 is a support member that supports the movable guide 107 and moves by a solenoid 114.
[0020]
The sheet P that has entered the sheet conveying device shown in FIG. 1 travels while being guided by the guide roller GR, but the movable guide 107 is initially in the position shown in FIG. Accordingly, the sheet P travels to the loop forming means LP with a low conveyance resistance.
[0021]
When the leading edge of the sheet P reaches the loop forming means LP, the solenoid 114 is activated to move the movable guide 107 to the position shown in FIG. In this way, a conveyance path with high conveyance resistance is formed. The timing for switching the conveyance path is determined by the sheet conveyance control program. A sensor is provided immediately upstream of the loop forming means LP, and the conveyance path is switched by driving the movable guide 107 based on the tip detection signal of the sensor. You may go.
[0022]
Since the guide roller GR is composed of a pair of driven rollers and only guides the sheet P, in the loop forming unit LP, most of the conveyance resistance of the sheet P becomes a load applied to the loop forming unit LP. Since the bending conveyance path formed by the movable guide 107 has a high conveyance resistance, the driving roller 101 conveys the sheet P in a state where the driving force is accumulated in the spiral spring 101d as indicated by θ1 and θ2 in FIG. . As described above, the accumulated driving force is large in a strong sheet P such as thick paper, and the accumulated driving force is small in a weak sheet such as thin paper.
[0023]
Based on the tip detection signal of the sensor 110, the movable guide 107 moves as shown in FIG. 3 to form a linear conveyance path. As a result, the conveyance resistance decreases, and the sheet P is conveyed by the driving force accumulated in the driving roller 101, and a loop is formed against the registration unit RR.
[0024]
The loop amount of the formed loop becomes larger as the sheet has a higher conveyance resistance such as cardboard. In this way, the loop amount of the sheet P formed upstream of the registration means RR is controlled according to the stiffness of the sheet P. Therefore, in the case of the strong sheet P, the loop amount is insufficient, and the leading edge control of the sheet P is insufficient, and in the case of the weak sheet P, the occurrence of paper folding and wrinkles is effectively prevented. Is done.
[0025]
FIG. 6 is a diagram showing an image forming apparatus and an automatic document feeder according to an embodiment of the present invention.
[0026]
The image forming apparatus GS includes an image forming unit 10, an image reading unit 20, and a paper storage unit 30. Reference numeral 10 denotes an image forming unit that forms an image on a sheet by electrophotography, 20 denotes an image reading unit that reads an image of a document and generates image data, and 30 denotes a sheet storage unit that stores the sheet.
[0027]
The image forming unit 10 includes a photoconductor 11. An electrophotographic process unit 12 forms a toner image on the photoconductor 11 by charging, exposure, and development, and transfers the toner image formed on the photoconductor 11 to a sheet. A recording paper resist unit KRB for supplying a sheet to the transfer position by controlling the posture in synchronization with image formation for forming a toner image on the photoconductor 11, a fixing device 13 for fixing the transferred unfixed image, A paper discharge unit 14 that supports the formed and discharged paper, a reverse conveyance unit 15 that reverses a sheet on which an image is formed on one side, a paper feed unit 16a, 16b, and 16c that feeds the paper from the paper storage unit 30, and a manual feed A paper feed unit 17 is provided.
[0028]
The image reading unit 20 includes a movable scanning unit 21 including a lamp and a mirror for illuminating an original, and two movable mirrors. The scanning unit 22 is movable at a half speed of the scanning unit 21, a lens, and an image sensor. And a platen glass 24 on which a document is placed.
[0029]
The paper storage unit 30 includes a plurality of paper storage units that can be individually inserted into and removed from the image forming apparatus main body. The paper storage units are paper feed trays 31a, 31b, and 31c in the illustrated example.
[0030]
The automatic document feeder JH includes a document feeder 41 on which documents are stacked, a document registration portion GRB that transports documents by controlling the conveyance timing and posture, a platen roller 42 that conveys documents at an image reading position, and a sheet that has been ejected. A document discharge tray 43 on which documents are stacked and a document reversing conveyance unit 44 that reverses the front and back of the document in duplex scanning are provided.
[0031]
The image reading unit 20 has a mode for reading a document conveyed in the automatic document conveyance device JH and a mode for reading a document placed on the platen glass 24.
[0032]
The sheet conveying apparatus shown in FIGS. 1 to 5 and described above is used for the recording paper registration unit KRB or the document registration unit GRB.
[0033]
【The invention's effect】
According to the invention of claim, since the loop amount formed in the resist portion is changed depending on the stiffness of the sheet to be conveyed, the conveyance timing control and the posture control in conveying the rigid sheet are insufficient, or the stiffness is weak Paper breakage and wrinkles that occur when a sheet is conveyed are well prevented.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a driving roller of a loop forming unit.
FIG. 5 is a diagram illustrating a change in position of a drive shaft and a driven shaft due to a difference in sheet conveyance resistance.
FIG. 6 is a diagram illustrating an image forming apparatus and an automatic document feeder according to an embodiment of the present invention.
[Explanation of symbols]
101, 103 Driving roller 102, 104 Drive roller 106 Fixed guide 107 Movable guide 108 Loop upper guide 109 Loop lower guide 110 Sensor LP Loop forming means RR Registration means

Claims (5)

A linear a and the conveyance resistance lower conveying passage can be formed and a high conveyance resistance bent the conveying path of the movable transport path forming means,
Driving means for switching from the bent conveyance path to the linear conveyance path by driving the movable conveyance path forming means;
A driving roller and a driven roller for conveying the sheet in the conveying path , wherein the driving roller connects the conveying unit, the driving shaft , and the conveying unit and the driving shaft, and the driving force of the driving shaft is transmitted to the conveying unit; a loop forming means having a resilient transmission means for accumulating the driving force according to the load exerted on the conveyor section as well as transmission to,
Anda register means disposed downstream of said conveying path and said loop forming means,
After conveying the conveyance path in which the sheet is bent by the loop forming unit, the sheet is switched to a linear conveyance path to convey the sheet, and the driving force accumulated in the elastic transmission unit is used to push the sheet against the registration unit. A sheet conveying apparatus that forms a loop on the sheet by contact . It said drive means after the leading edge of the sheet is introduced into straight the conveyance path, to claim 1, characterized in that forming said transport path bent by driving the movable feed path forming means The sheet conveying apparatus according to the description. Has a sensor located immediately upstream of said register means, said drive means, based on the leading edge detection signal by the sensor, the linear from the transport path bent by driving the movable feed path forming means The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is switched to a conveying path. An image forming apparatus , wherein the sheet conveying device according to claim 1 is used as a recording paper feeding unit that supplies a sheet to a transfer position.   An automatic document conveying device comprising the sheet conveying device according to claim 1.

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