JPH11222344A - Paper postprocessor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate turbulence of an image caused by a speed difference by switching a torque limiter device to either of a weak operational force state of idly rotating in costant torque or more when an electromagnetic clutch is turned off and a strong operational force state of transmitting motive power in a direct coupled state when the electromagnetic clutch is turned on. SOLUTION: Input of motive power to a pulley 13b1 is transmitted to a carrier roller 4a in a direct coupled state when current-carrying to a coil 13a2 is put in an ON state, and is transmitted by frictional force since a torque limiter 13b functions when the current-carrying to the coil 13a2 is put in an OFF state. The torque limiter 13b can also variably control transmission torque by an inputted electric signal. A torque limiter device 13 can control ON/OFF of the current-carrying to a coil of an electromagnetic clutch 13a and the transmission torque to the torque limiter 13b by a signal from a paper sheet postprocessor side control means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet post-processing apparatus used in conjunction with an image forming apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art A sheet post-processing device provided with an image forming apparatus, wherein a pair of discharge rollers provided at the most downstream position on the image forming apparatus side and the sheet post-processing apparatus side When the same sheet is transported in common with a pair of transport rollers provided at the most upstream position in the above, a paper post-processing device in which the paper transport speed by the transport rollers is higher than the paper transport speed by the discharge rollers is there.

The following cases can be considered as the reasons why the above-mentioned speed difference occurs between the sheet conveying speed in the image forming apparatus and the sheet conveying speed in the sheet post-processing apparatus. A type in which the image forming apparatus transfers the toner to the transfer paper by passing the image-transferred sheet through a fixing device, or in a diazo type image forming apparatus, a sheet in a post-processing apparatus such as a sorter or a stapler. In the transport speed of the paper and the transport speed of the paper in the fixing device, while the speed in the fixing device is a speed defined by the fixing conditions,
Since there is no such limitation in the post-processing apparatus, and the demand for shortening the image processing time, the speed in the post-processing apparatus is generally higher than the speed in the fixing apparatus.

When a user uses a paper post-processing apparatus and an image forming apparatus, which are appropriately selected from various types of paper post-processing apparatuses and image forming apparatuses, as a combined system, the paper feeding speed and image in the paper post-processing apparatus are used. There is a difference between the sheet feeding speed in the forming apparatus and the sheet feeding speed. Also in this case, generally, the speed in the post-processing device is higher than the speed in the fixing device.

As described above, when there is a difference in the feed speed between the sheet feed speed in the image forming apparatus and the sheet feed speed in the sheet post-processing device, a pair of the pair provided at the most downstream position on the image forming device side. When the same sheet is commonly transported by the paper discharge rollers and the pair of transport rollers provided at the most upstream position on the paper post-processing device side, an excessive tension acts on the paper and the fixing roller The image may become dirty due to the slip between the paper and the paper.

In order to avoid this, the image is separated between when the leading edge of the sheet is held by the sheet post-processing device and when the trailing edge of the sheet is held by the fixing roller and when the trailing edge of the sheet is separated from the fixing roller. The paper feed speed in the forming apparatus is changed. In this case, the change is from the feed speed determined by the fixing device to a high feed speed determined by the paper feed speed. The amount of change in the speed is 3 to 5% in the case of a small change, and is 200% in the case of a large change in order to shorten the so-called first copy time.

To cope with such a speed change,
(A) receiving a timing signal from the image forming apparatus side,
(B) In the case of a type in which the timing signal is not output from the image forming apparatus side to the control apparatus on the post-processing apparatus side, in order to absorb a speed difference between the image forming apparatus and the post-processing apparatus, When a torque greater than a certain value is applied to the drive shaft of the transport roller by the tension of the paper, a torque limiter that acts to idle a surplus while maintaining the transmission of a predetermined amount of torque required for paper feeding is attached. Such a method is adopted. Japanese Patent Application Laid-Open No. 60-193361, Japanese Patent Application Laid-Open No.
139463, JP-A-1-197263,
There is an example disclosed in JP-A-2-292076.

[0008]

However, in the above case (a), when the speed change is large, the sheet between the image forming apparatus and the sheet post-processing apparatus is caused by the speed difference caused by a slight timing shift. The sheet may be bent and scratched by touching a part of the apparatus, or the image may be stained by slip between the fixing roller and the sheet.

In the case (b), the lower the set torque value of the torque limiter, the more the excessive force is not applied to the paper, and the better the result of the image contamination in the fixing device is. However, in order to secure the conveying force after the trailing edge of the sheet is separated from the image forming apparatus side, the value must be increased to some extent, and depending on the conditions, the fixing roller may be fixed as in the case of (a) above. The image may be stained due to the slip between the sheet and the paper.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet post-processing apparatus which has a feeding speed higher than that of an image forming apparatus and in which image disturbance due to a speed difference is eliminated by simple means. .

[0011]

The present invention has the following configuration to achieve the above object.

(1) A sheet post-processing device attached to an image forming apparatus, wherein a pair of discharge rollers provided at the most downstream position on the image forming apparatus side and the sheet post-processing device When the same sheet is transported in common with a pair of transport rollers provided on the side, in the sheet post-processing apparatus in which the paper transport speed by the transport rollers is higher than the paper transport speed by the discharge rollers, In the driving system of the driving roller, a torque limiter device configured by a combination of a torque limiter and an electromagnetic clutch is provided, and when the electromagnetic clutch is turned off, the torque limiter idles at a certain torque or more. When the operating force is weak and when the electromagnetic clutch is turned on, the torque limiter is not directly running without idling and the power is transmitted in a directly connected state. To both allowed switching of (claim 1).

(2) In the sheet post-processing apparatus described in (1), the weak state is switched to the strong state when the trailing end of the sheet is separated from the discharge roller.

(3) In the sheet post-processing apparatus described in (1), the strong state is switched to the weak state at least immediately before the leading end of the sheet reaches the transport roller, and the weak state is changed to the weak state. It is held during the time when it is held in common by the transport roller and the discharge roller (claim 3).

(4) In the sheet post-processing apparatus described in (2) or (3), sheet detection information from a sheet detection sensor provided in a sheet conveyance path of the image forming apparatus is input to the control means. The control means sets the strength of the operating force of the torque limiter and the timing of switching (claim 4).

(5) In the sheet post-processing apparatus described in (4), the control means controls the sheet detection sensor based on sheet detection information from the sheet detection sensor provided in the nip portion of the discharge roller. When the detection signal is being output, the electromagnetic clutch is turned off, and when the sheet detection sensor is not outputting the sheet detection signal, the electromagnetic clutch is turned on (claim 5).

[0017]

FIG. 1 shows an example of a sheet post-processing apparatus 5 provided in addition to an image forming apparatus 3. In the present invention, the sheet post-processing device 5 includes various devices such as a stapler and a sorter.
A sorter is illustrated. Further, the image forming apparatus 3 includes a fixing device. The image forming apparatus 3 is not limited to an image forming method (electrophotographic method, diazo method). In this example, after forming an electrostatic latent image on the image carrier, the electrostatic latent image is visualized with toner, and the visible image is transferred to paper.
A description will be given of an image forming apparatus of a type in which a sheet is passed between rollers for heating and pressurizing, fixed, and discharged.

FIG. 1 shows only those components necessary for the description of the present invention among the internal configuration of such an image forming apparatus 3. The paper fed from the paper feed tray 6 is visualized by the toner in the image forming unit 7. The image forming section is provided with a photosensitive drum, around the photosensitive drum, a charging device, an exposure device, a developing device, a transfer device,
A cleaning device and the like are provided.

The sheet carrying the toner image in the image forming section 7 reaches a fixing device 8 and is given heat and pressure while passing between a pair of rollers 8A in the fixing device 8, so that the toner image is fixed. You. The sheet on which fixing has been completed is sent to the sheet post-processing device 5 by a sheet discharge roller 10 including a pair of rollers at the most downstream side on the sheet conveyance path of the image forming apparatus 3. The image forming apparatus 3 is provided with a main body side control unit 20 composed of a CPU, which controls an image forming process in the image forming apparatus 3 and controls a sheet conveying timing, a sheet conveying speed, and the like.

In this example, the sheet post-processing apparatus 5 comprises a sorter having a sorting function. When performing image processing of a plurality of sets, the sheets sequentially fed from the sheet discharging rollers 10 are transport rollers 4a forming a pair from bottom to top.
4b and transport rollers 4a 'and 4b'
The path of the paper is changed by the deflection claw 11a, 11b, 11c which operates sequentially, and the curved surface of the guide 15, and is passed through a pair of conveyance rollers 2a, 2b, 2c, 2d, etc., to the paper discharge tray constituting the paper discharge unit 2. Distributed from top to bottom. In the case of one-sheet processing, the sheet is discharged to a predetermined discharge tray.

In the pair of transport rollers 4a 'and 4b' and the pair of transport rollers 4a and 4b or the pair of transport rollers 2a, 2b, 2c and 2d in the sheet post-processing apparatus 5, the most upstream side Of the pair of transport rollers 4a and 4b provided on the other side, if one of the transport rollers 4a is a drive roller and the other transport roller 4b is a driven roller, the drive system of the transport roller 4a as the drive roller includes: A torque limiter device 13 configured by combining a torque limiter and an electromagnetic clutch is provided. The control of the sheet feeding speed and the sorting in the sheet post-processing device 5 is performed by a CP provided in the sheet post-processing device 5.
U is controlled by the sheet post-processing device-side control means 25, and the torque limiter 13 is also controlled by the sheet post-processing device-side control means 25.

In the image forming apparatus 3 and the sheet post-processing apparatus 5, as shown in FIG. 1, a sheet 12 having a length such that the sheet is conveyed while being simultaneously held by a discharge roller 10 and conveyance rollers 4 a and 4 b. Can be sent without damaging the image.

For this reason, as shown in FIG. 2, a torque limiter device 13 is used.
3a and a torque limiter 13b. The electromagnetic clutch 13a3 includes a yoke 13a1, a coil 13a2 fixed to the yoke 13a1, a clutch plate 13a4, a disk 13a4, and the like. Yoke 13
a1 is fixed to a stationary member, and the shaft 4 of the transport roller 4a is
J is configured in a non-contact manner. Similarly, the coil 13a2 is configured so as not to contact the shaft 4J. Clutch plate 1
3a3 is formed integrally or integrally with the shaft 4J, and is made of a magnetic material such as an iron plate. The disk 13a4 is fixed to the side surface of the pulley 13b1 constituting the torque limiter 13b, faces the clutch plate 13a3, and is not in contact with the clutch plate 13a3. However, when the coil 13a2 is energized as described later, , Clutch plate 13
Attachment to a3 causes rotation integrally with the clutch plate 13a3, that is, integrally with the shaft 4J.

The torque limiter 13b includes a pulley 13b1
And a roller-shaped sliding contact body 13b2 integrally or integrally formed with the shaft 4J. The inner diameter of the pulley 13b1 is in frictional contact with the outer peripheral surface of the sliding member 13b2, and the transmission force is determined by the friction coefficient μ and the contact pressure.

Gear teeth 13 are provided on the outer periphery of the pulley 13b1.
c is formed, and a toothed belt (not shown) is meshed with the teeth 13c. Rotary power is input to the pulley 13b1 via this belt. Alternatively, a configuration in which a drive gear connected to a drive source is engaged with the teeth 13c may be employed.

When the coil 13a2 is not energized, the clutch plate 13a3 and the disk 13a4 are separated from each other, and the power to the pulley 13b1 slips according to the resistance applied to the transport roller 4a to slip on the shaft 4J (transport roller). 4a). When the coil 13a2 is energized, the coils 13a2, clutch plates 13a3,
A magnetic field is formed around the disk 13a4 and the yoke 13a1, and the disk 13a4 is drawn together with the pulley 13b1 toward the clutch plate 13a3, and the clutch plate 13a3
Then, the disk 13a4 comes into close contact with the magnetic attraction and rotates integrally.

As described above, if the power supply to the coil 13a2 is turned on, the power input to the pulley 13b1 is transmitted to the transport roller 4a in a directly connected state, and
If the power supply to a2 is turned off, the torque limiter 13b functions and is transmitted by frictional force.
Further, the torque limiter 13b can variably control the transmission torque by the input electric signal.

As shown in FIG. 1, the torque limiter 13 turns on the power supply to the coil of the electromagnetic clutch 13a in response to a signal from the sheet post-processing device side control means 25.
Off and transmission torque to the torque limiter 13b can be controlled.

On the other hand, a paper detection sensor S is provided in the nip of the paper discharge roller 10, and an information transmission path is configured so that the main body side control means 23 can receive the paper detection information by the paper detection sensor S. Have been. The main body side control means 23 and the sheet post-processing apparatus side control means 25 are connected by an interface signal line.
The transport speed F3 of the sheet in the image forming apparatus 3 is the same as the fixing speed in the fixing device 8, and the same speed for the roller 8A and the sheet discharging roller 10. Further, the paper transport speed F5 in the paper post-processing device 5 is set to a transport speed F5 higher than the transport speed F3 in order to increase the paper processing speed.

The sheet post-processing device-side control means 25 controls the torque limiter 13 as shown in FIG. 3 based on the information from the sensor. In FIG. 3, when the sheet detection sensor S detects a sheet in step (1), the process proceeds to step P2, where the coil is detected. The power supply to 31a2 is turned off, that is, the electromagnetic clutch is turned off. As a result, the torque limiter 13b functions and the operating force of idling at a certain torque or more is weakened, and the sheet is pulled by the sheet discharging roller 10 or the roller 8A and slipped before being slipped by the torque limiter 13b. It prevents the image from being damaged by idling.

This weak state continues until the trailing edge of the sheet passes the sheet detection sensor S. Accordingly, the trailing end of the sheet is added to the discharge rollers 10, and the leading end also includes the transport rollers 4a,
4b, the torque limiter 1
Since the slip occurs at the portion 3b, there is no slip between the paper and the roller, and the paper and the image portion of the paper are not damaged. Note that the transmission torque at the torque limiter 13b is
It is assumed that the power is adjusted so that the power is transmitted with an appropriate slip, or that the power is set under the control of the sheet post-processing apparatus side control means 25.

When the trailing edge of the sheet passes through the discharge roller 10, the sensor S in step P1 in FIG. 3 turns off. Then, the process proceeds to Step P3, where the electromagnetic clutch 13b is turned on. That is, the disk 13a4 comes into close contact with the clutch plate 13a3 and rotates integrally with the pulley 13b1 and the shaft 4J in a directly connected state, and the operating force for transmitting power in the directly connected state without idling of the torque limiter is strong. The sheet is conveyed at a transport speed F5 higher than the transport speed F3. As described above, when the trailing edge of the sheet has run out of the nip portion of the sheet discharging roller 10, the torque limiter 13b is switched from the weak state to the strong state, and the sheet is fed at a high transport speed in the sheet post-processing device 5. However, since the rear end side of the sheet has already passed through both the fixing device 8 and the sheet discharge roller 10, there is no problem.
Since the paper is sent at a high transport speed, the processing time can be reduced.

In this way, the torque limiter 13 switched to the strong state causes the leading end of the next sheet
The state is switched from the strong state to the weak state immediately before reaching a and 4b. In this way, the leading edge of the paper is
By the time it reaches a and 4b, it can be kept in a weak state with a margin.

There is no problem if the feed speed F3 on the image forming apparatus 3 side and the feed speed F5 on the sheet post-processing apparatus 5 side are completely the same, but they are different as described in the problem of the prior art. In general, when the trailing end of the paper 12 is still held by the roller 8A of the fixing device 8, the leading end of the paper 12 is similarly transported by the transport rollers 4a, 4a.
b may be added.

Control for the torque limiter device 13 is as follows:
Since the processing is performed by the sensor S, the main body side control means 23, the paper post-processing apparatus side control means 25, etc., the trough limiter device is automatically performed, and the image forming processing is performed at a high processing speed without damaging the image. Can be.

The setting position of the sensor S is not limited to the nip portion of the paper discharge roller 10 but may be provided at an arbitrary position in the paper transport path on the image forming apparatus 3 side. In this case, the main body side control means 23 or the paper postscript medical device side control means 25
Thus, the time from the point of detection of the leading edge of the sheet is counted, and the time until the leading edge of the sheet is transported to the nip portion of the transport rollers 4a and 4b is calculated from the transport speed of the paper and the time is calculated. So that the torque limiter 13
Is controlled to be in a weak state.

In the above-described example, the case where the torque limiter device is provided in the drive system of the drive roller of the pair of transport rollers provided at the most upstream position on the side of the sheet post-processing device 5 has been described. However, in order to cope with the case where the same paper is simultaneously transported together, for models that are supposed to process such long papers, a pair of transport rollers provided at the most upstream position Not limited, transport rollers 4
a ', 4b' and the transport rollers 2a, 2b, 2c, 2d
It is necessary to appropriately provide a similar torque limiter device and ancillary devices therefor.

[0038]

According to the first aspect of the present invention, in a sheet post-processing apparatus having a higher conveying speed than in the image forming apparatus, the image drive caused by the speed difference is carried by the sheet post-processing apparatus. The problem can be solved by simple means without switching control of the motor speed and without using a special and expensive motor. According to the second aspect of the present invention, it is possible to accurately obtain the timing for transporting the sheet at the transport speed of the sheet post-processing apparatus,
It can be transported without any problems. According to the third aspect of the present invention, it is possible to convey the sheet without damaging the image without adjusting the conveying speed on the sheet post-processing apparatus side. According to the fourth aspect of the present invention, the sheet can be automatically conveyed without damaging the image by the control means.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a sheet post-processing apparatus according to the present invention together with an image forming apparatus.

FIG. 2 is a schematic configuration diagram illustrating a configuration example of a torque limiter device according to the present invention.

FIG. 3 is a flowchart showing a control procedure in a control unit according to the present invention.

[Explanation of symbols]

 3 Image Forming Apparatus 4a Driving Roller 5 Paper Post-Processing Apparatus 10 Discharge Roller 13 Torque Limiter 13a Electromagnetic Clutch 13b Torque Limiter 23 Main Body Control Unit 25 Paper Post-Processing Unit Control Unit S Paper Detection Sensor

Claims (5)

[Claims] 1. A sheet post-processing device attached to an image forming apparatus, comprising: a pair of discharge rollers provided at a most downstream position on the image forming device side; A sheet post-processing device in which the paper feed speed by the transport rollers is larger than the paper feed speed by the discharge rollers when the same paper is transported in common with a pair of transport rollers provided in the transport rollers; An operation in which a torque limiter device constituted by a combination of a torque limiter and an electromagnetic clutch is provided in a drive system of a driving roller, and the torque limiter device idles at a predetermined torque or more when the electromagnetic clutch is turned off. The state in which the force is weak and the state in which the operating force for transmitting power in the directly connected state without idling when the electromagnetic clutch is turned on is strong. A sheet post-processing apparatus characterized in that it is also switchable. 2. The sheet post-processing apparatus according to claim 1, wherein
The sheet post-processing device switches from the weak state to the strong state when the trailing end of the sheet is separated from the sheet discharge roller. 3. The sheet post-processing apparatus according to claim 1, wherein
At least immediately before the leading end of the sheet reaches the transport roller, the strong state is switched to the weak state, and the weak state is changed while the sheet is commonly held by the transport roller and the discharge roller. And a sheet post-processing device for holding. 4. A sheet post-processing apparatus according to claim 2, wherein the control means receives sheet detection information from a sheet detection sensor provided in a sheet conveyance path of the image forming apparatus.
A sheet post-processing apparatus, wherein the control means sets the strength of the operating force of the torque limiter and the timing of switching. 5. The sheet post-processing apparatus according to claim 4, wherein
The control unit is configured to turn off the electromagnetic clutch when the sheet detection sensor is outputting a sheet detection signal based on sheet detection information from the sheet detection sensor provided in the nip portion of the discharge roller, The sheet post-processing device controls the electromagnetic clutch to be in an ON state when the sheet detection sensor does not output a sheet detection signal.