JPH07247039A - Device and method for feeding and separating sheet using retard roll - Google Patents

Abstract

PURPOSE: To reduce misfeed and simultaneous multiple sheet feeding in a copying machine by frequently and continuously adjusting the standard force of a retard nip, which is exerted to the sheet fed to a sheet passage from a stack. CONSTITUTION: If a sheet 17 does not reach a misfeed sensor 14 within a predetermined length of time, a micro-processor controller 21 recognizes it as an occurrence of a nearly misfeed. In the next step, the micro-processor controller 21 detects the phased quantity of changes in optimum perpendicular for the types of the sheets 17 to be fed based on either the property of the predetermined sheet or the dynamic input from an opaque sensor 22 and feeds a retard roll 11 toward a feed roll 10 utilizing a stepper motor 18 to increase the perpendicular force at a retard nip 12. In the case where the increased perpendicular force of the retard nip 12 is not great enough to pass a sheet by means of the retard nip 12, the micro-processor controller 21 makes the retard nip 12 repeat the improvement of its perpendicular force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for feeding a sheet in a copying machine and the apparatus therefor. More particularly, the present invention relates to a sheet feeding system that uses a microprocessor controller to monitor the operation of the sheet feeding apparatus and check for abnormal feeding conditions such as feeding errors and multiple sheet feeding. Regarding

[0002]

2. Description of the Related Art When such an abnormal condition occurs,
Considering the characteristics of the sheet, the microprocessor controller adjusts the normal force of the retard nip on the sheet to be fed to correct the abnormal condition without operator intervention. In a typical copying machine, the sheets are contained in a sheet tray and the sheets are fed to the copying machine one by one. Sheets are removed from the top of the stack one by one by a feed roll that engages the top surface of the sheets and rotates to remove the sheets from the stack and feed them into the sheet path. Such sheet feeding systems often include a sensor located in the sheet path downstream of the feed roll and coupled to the microprocessor controller of the copier to detect the sheet. . This sensor detects a feeding error by the following method. After sending a signal to feed the sheet to the feed roll, the microprocessor controller determines the length of time between this signal and the return signal emitted by the misfeed sensor when the sheet is detected. To measure. If the measured time exceeds a predetermined maximum value, the microprocessor controller recognizes a misfeed condition. Then, in a typical copier, the microprocessor controller sends a signal to the operator that the sheet has been mis-fed and work cannot continue until the mis-fed sheet is manually removed. .

Misfeeds occur in this type of copying machine for a variety of reasons such as edge welding, high stiction and reduced friction within the feed components. A problem associated with the operation of a typical sheet feeder is multiple sheet feeding, where multiple sheets are fed simultaneously through the sheet path rather than a single sheet. For this reason, the main purpose in designing a sheet feeding system is to improve the ability of the system to handle various types of sheets without feeding errors or feeding a large number of sheets. US Patent No. 4,
561 and 644 disclose a sheet feeding device and a sheet separating device. This device adjusts the vertical force exerted on the stack of sheets by the feed mechanism to reduce misfeeds and multiple sheet feeds. This invention makes the whole description of this patent specification into a part of description of this specification by quoting this prior art. This device includes a sensor similar to the misfeed sensor described above. If the sensor cannot detect the sheet within a predetermined time, the vertical force applied to the sheet stack is increased to correct the misfeed condition. The sheet feeder and separator are mounted on a frame that pivots about an axis. When a sheet is detected by the sensor, the solenoid actuates to pivot the frame, which reduces the vertical force on the stack and prevents multiple sheet feeds.

While the prior art seeks to reduce the operator hassle required to correct abnormal feeding conditions, such systems generally operate in a trial and error manner, It does not react to the characteristics of the sheet being fed, nor to repeated problems.

[0005]

SUMMARY OF THE INVENTION Initial settings are created based on the type of sheet being fed, the operation of the sheet feeding device is actively monitored, and frequent adjustments are made in response to abnormal feeding conditions. What is needed is an "intelligent" copier that can improve the initialization to avoid repeating problems.

[0006]

SUMMARY OF THE INVENTION The present invention provides frequent and continuous adjustment of the standard force of the retard nip applied to the sheets fed from the stack into the sheet path to eliminate misfeeds in copying machines. Designed to reduce sheet feeding. The retard nip vertical force increases when the sheet feeding system detects a feeding error state or a state close thereto, and the retard nip vertical force increases when the apparatus detects a multi-sheet feeding state or a state close thereto. Is reduced. The optimum magnitude of the retard nip normal force to be applied to a particular sheet can be determined and delivered by a microprocessor controller using a look-up table of optimum normal force values for various types of sheets. The sheet type to be determined is determined either by a sensor or by the operator inputting information into the system. These optimal retard nip normal forces change the physical position of the retard roll in the sheet feeder with respect to the feeder mechanism, i.e. raise the retard roll by a solenoid, stepper motor or similar device.
Or it can be achieved by lowering it. With the present invention, it is possible to create a copier default setting based on the characteristics of the sheet to be fed, when the microprocessor controller detects that frequent adjustments have been made to the retard nip normal force. You can change the default settings. Thus, the sheet feeding system can compensate for the reduced friction that occurs when roll wear exceeds the life of the device without requiring manual correction by the operator.

The present invention seeks to reduce downtime in copying machines by automatically correcting misfeeds and multi-sheet feed conditions. Thus, the operator does not have to open the machine as often to clean the sheet path as is normally required for conventional types of feed rolls in sheet feeding systems. This is desirable because it improves the efficiency of this duplication process, which makes it more reliable to the machine and more attractive to the consumer. For this reason, the operator finds that this copier is more intelligent than a machine without self-correction capability.

[0008]

1 is a schematic view showing a simplified feed roll type sheet feeding apparatus which is usually used in a copying machine, in which a sheet 1 is moved from a sheet stack 2 to a sheet passage 3. In this apparatus, the friction roll 4 is mounted so as to rotate in a fixed position on the sheet stack tray 5. A motor (not shown) rotates the roll 4 in the direction as indicated by 6. The rotation of the roll 4 causes the outer surface of the roll 4 to feed the sheet 1 in the direction 7 into the sheet path 3. Since the roll 4 is mounted in a fixed position, the vertical force of the roll 4 on the upper sheet 1
As a result, the frictional force that pushes the sheet 1 when the roll 4 rotates is substantially constant. The apparatus shown in FIG. 1 can change the seat characteristics, reduce the friction, or move the seat 1 into the seat passage 3
Cannot be adjusted to accommodate other factors that affect the force required to deliver to. FIG. 2 shows an embodiment of the sheet feeding apparatus according to the present invention, which is used in a copying apparatus or a similar apparatus. The feeding roll 8 feeds the sheet 17 from the sheet stack 9. The feeding roll 10 moves at substantially the same speed as the feeding roll 8 and feeds the sheet 17 to the sheet path 15 of the copying apparatus. Alternatively, the feeding belt can be used as a combination of the feeding roll function and the feeding roll function. Such a device is described in US Pat. No. 4,561,6.
No. 44, the present invention makes the entire description of this patent specification into a part of the description of this specification by quoting this prior art. The retard roll 11 is configured so that excess paper is not sent to the retard nip 12 at the position where the feeding roll 10 contacts the retard roll 11. The retard roll 11 has a setting condition that can be changed using a solenoid, that is, a linear step motor 18,
It is connected to a spring biasing mechanism 13 and is driven by a shaft connected to a slip clutch 16. The slip clutch 16 is provided with a twisting device that applies a torque force in a direction opposite to the direction in which the feeding roll 10 rotates, so that the retard roll 11 prevents the slip clutch 16 from rotating. Further, an inlet guide (not shown) is fed to the roll 8
It is also possible to separate the slugs of a plurality of sheets attached to each other by arranging the sheet between the sheet feeding roll 10 and the feeding roll 10 and performing a gate function.

The microprocessor controller 21 is shown in FIG.
The operation of the sheet feeding device shown in is controlled. The microprocessor controller 21 may be composed of, for example, an 8085 type controller or a device functionally similar to this. The instructions may be provided as hard code on the device, but are typically EPROM devices (erasable programmable ROM) to allow easy software upgrades. The microprocessor controller 21 may be coupled to the memory 23 of the copier. The sheet feeder of FIG. 2 uses multiple sensors to provide information about the copier to the microprocessor controller 2.
1 to provide. For example, the opacity sensor 22 is used to determine the thickness of the sheet 17 as it is fed from the stack 9. Such a sensor is disclosed in US Pat. No. 5,138,178. Further, the misfeed sensor 14 is used to detect the sheet 17 as it passes through the retard nip 12. Finally, when the retard roll 11 rotates in the direction of the sheet stack 9, as occurs during multi-sheet feeding,
The retard roll 11 is a microprocessor controller 2
1 may be coupled with a motion sensor 26 capable of sending a signal.

The sheet feeder may include a user interface 24 coupled to the microprocessor controller 21. The user interface 24 typically includes data entry keys to allow the operator to control certain parts of the copy operation and provides information such as the size of the original, the type of copy paper and the desired number of copies. To the microprocessor controller 21. In addition, the user interface 24 includes a display to provide the operator with information such as job status and error conditions. In the present invention, a semi-active retard roll or a fixed retard roll may be used, but the retard roll 11 shown in the figure is an active retard roll. The active retard roll 11 is driven by a motor (not shown) in the direction opposite to the direction of movement of the sheets 17, and acts to push the excess sheets back into the sheet stack 9. The active retard roll 11 rotates at approximately twice the speed of the feed roll 10 and the payout roll 8. The semi-active retard roll can be driven a small distance in the opposite direction to the movement of the seat by a twist or similar device, rather than being rotated by a motor. Fixed retard rolls cannot rotate and merely physically prevent excess sheets from being fed.

The operation of the active retard roll 11 varies depending on the number of sheets passing through the retard nip 12. When there is no sheet in the retard nip 12, the torque force applied by the feeding roll 10 on the retard roll 11 is sufficiently larger than the torque force applied by the slip clutch 16 and is in the same direction as the feeding roll 10. The retard roll 11 is driven. Similarly, as shown in FIG. 2, only one sheet 17 is used for the retard nip 1.
2, the torque force applied by the feeding roll 10 on the retard roll 11 via the sheet 17 is still sufficiently larger than the torque force of the slip clutch 16, and the retard roll is in the same direction as the feeding roll 10. 11
To drive. However, when there are two or more sheets in the retard nip 12, the torque force applied by the feed roll 10 on the retard roll 11 is no longer greater than the torque force of the slip clutch 16. For this reason, the feed roll 10 moves the top sheet in the direction away from the sheet stack 9, and the retard roll 11 rotates in the opposite direction so that the excess sheet returns to the sheet stack 9. Looking at the dynamic forces present in the sheet feeding system of FIG. 2, the driving force on the sheets removed from the sheet stack by the roll device is generally given by F _drive = Nμ. here,
N is a vertical force acting on the sheet, and μ is a rolling friction coefficient. For heavy weight sheets (eg, 49.83 kilogram bond paper), a significant amount of drive force is required to remove sheet 17 from sheet stack 9. However, for light sheets (eg, 5.9 kilogram bond paper), a drive force of this magnitude is unsuitable. Lightweight paper, for example, has relatively low inner sheet-to-sheet friction properties from the stack and requires relatively little force to separate the individual sheets from the stack. In fact, using too much driving force will damage the sheet. Since it is difficult to change the coefficient of friction of the roll during operation of the copier, another means of adjusting the drive force according to the above equation is:
It turns out that it is to adjust the vertical force acting on the seat.

More specifically, the dynamic force acting on the sheet of the sheet feeding system according to the present invention is represented by F in FIG.
_Shown as _nudger and F _retard . F _nudger represents the force applied to the sheet by the payout roll 8, and
_retard represents the force applied to the sheet 17 at the _retard nip 12. Sheet 1 with pay-out roll 8 in FIG.
The driving force acting on 7 can be represented by F _nudger = N _nudger μ _rs . Here, N _nudger is the vertical force on the payout roll, and μ _rs is the friction coefficient between the roll and the sheet. Take the sheet 17 from the sheet stack 9 and use the retard nip 1
Driving force F _{nudger on the pay-} out roll 8 in order to feed
Must be greater than the sum of the static frictional force between the sheet 17 and the second sheet on the sheet stack 9 plus the drag force on the sheet 17 as the sheet moves out of the sheet stack 9. These drag forces include electrostatic forces and other frictional forces acting on the sheet 17. In detail, F _nudger > (N _nudger + W) μ _ss + drag, where W is the weight of one sheet,
μ _ss is the coefficient of friction between sheets. However, if an excessively large driving force F _nudger is applied to the _pay- out roll 8, one or more sheets are pulled from the sheet stack 9 and a multi-sheet feeding occurs. To this end, in addition to the above equation, the driving force F _nudger must be less than the static friction force between the second and third sheets on the sheet stack 9. Specifically, (N _nudger + W) μ _s1s2 + drag force <F _nudger <(N _nudger
+ 2W) μ _s2s3 , where μ _s1s2 is the coefficient of friction between the first and second sheets, and μ _s2s3 is the coefficient of friction between the second and third sheets.

Considering the feed roll 10 and the retard roll 11, the driving force acting on the sheet 17 in the retard nip 12 with the feeding force F _nudger applied is as follows. F _nudger + F _retard = N _nudger μ _rs + N _retard μ _rs where F _retard is the driving force applied by the combination of the feed roll and the retard roll, and N _retard is
The vertical force applied at the retard nip. The total driving force is the static friction force between the seat 17 and the second seat on the seat stack 9, the drag force on the seat 17 as the seat moves out of the seat stack 9 and the torque force applied to the slip clutch 16. Must be greater than the sum of. Specifically, F _nudger + F _retard > (N _nudger + W) μ _ss + SCT /
R + drag. Where SCT is the slip clutch torque force and R
Is the radius of the retard roll. When more than one sheet is removed from the sheet stack 9 and enters the retard nip 12, the driving force required to feed the top sheet into the sheet passage 15 is the driving force between the sheet 17 on the payout roll 8 and the second sheet. Must be greater than the sum of the static friction force between them, the kinetic friction force between the sheet 17 and the second sheet on the feed roll 10 and the drag force on the sheet 17.
Specifically, F _nudger + F _retard > (N _nudger + W) μ _ss + N _retard
μ _ss + drag.

At the same time, the force required for the nth additional sheet not to pass through the retard nip 12 is expressed as follows. (N _retard + (n-1) W) μ _snsn-1 + (N _nudger +
(N-1) W) μ _{snsn -1} <SCT / R + (N _nudger + N
W) μ _{snsn + 1} + drag The vertical force N applied at the retard nip 12 by adjusting the position of the retard roll 11 with respect to the feeding roll 10.
_{The retard} changes. Therefore, the total driving force applied to the seat will change. In order to accurately feed different types of sheets (eg different weights of paper),
Varying the retard nip normal force is accomplished by raising and lowering the retard roll 11 using a spring biasing mechanism 13 coupled to both the retard roll 11 and a solenoid or linear step motor 18. The retard nip normal force adjustment is generally in the range of 90.6 grams to 1812 grams. The sheet feeding system of the present invention can recognize a feeding error or a possibility of feeding a large number of sheets, and adjusts the retard nip vertical force reactionally so that an abnormal feeding state does not actually occur. it can. Such a possibility becomes apparent, for example, by a condition close to repeated misfeeds, which necessitates adjusting the retard nip normal force of successive sheets to feed the sheets into the sheet path. Recognizing such possibilities, the sheet feeding system can be a safeguard to adjust the default settings depending on the type of sheets to be fed.

In general, a sheet feeding system constructed and operated in accordance with the present invention will detect abnormal operating conditions such as feeding errors or multiple sheet feeding in the following manner:
And can respond to it. Referring again to FIG. 2, in response to the operator's initial operation of the machine, the microprocessor controller 21 causes the retard roll 11 to
Determine the default setting for the height of. This default setting is
For example, it can be determined by the information retrieved from the look-up table 25 stored in the memory 23 based on the characteristics of the paper input by the operator. Alternatively, the microprocessor controller 21 can maintain a default setting that corresponds to the size of the paper being used for the copy, or use whatever setting it had when the previous copy operation was completed. I'm dying. After confirming the initial settings, the microprocessor controller 21 signals the stepper motor 18 to set the retard roll 11 to an appropriate height. After initializing the retard roll 11, the microprocessor controller 21
Sends a signal to the sheet feeding device to take out the sheet 17 from the sheet stack 9 and send it to the sheet passage 15. When the sheet 17 remains in the sheet stack 9, the opacity sensor 22 approximately determines the thickness of the sheet 17 and can be used to provide information to the microprocessor controller 21. The microprocessor controller has a misfeed sensor 1 located close to the retard nip 12.
4 to determine if sheet 17 was successfully fed.

If the sheet 17 does not reach the feeding error sensor 14 within a predetermined time, the micro sensor control device 2
1 recognizes a state close to a feeding error. The microprocessor controller 21 then determines, based on either the previously determined sheet properties or the dynamic input from the opacity sensor 22, the optimum vertical force step for the type of sheet 17 to be fed. The amount of change to be made, and the stepper motor 18 is used to replace the retard roll 11 with the feed roll 10.
The vertical force N _retard at the _retard nip 12 is increased by feeding in the direction of. This displacement of the retard roll 11 must be small so as not to damage the seat 17. If the increased retard nip normal force is still small to pass the sheet through the retard nip 12, the microprocessor controller 2
1 can repeat the step of the retard nip vertical force repeatedly. A more detailed description of the self-correction process is provided below with reference to FIGS. 3, 4 and 5. Retard nip vertical force is applied to the retard nip 12
Adjustments can also be made to correct multi-sheet feed conditions such as those that occur when sheets are fed to the. The multi-sheet feeding, or a state close to this, occurs when the sheet 17 cannot freely pass through the retard nip 12 because the force applied at the retard nip is too large, for example. In such a case, the slip clutch 16 of the active retard roll 11
Returns successive sheets in the direction of the sheet stack 9.
The backward movement of the retard roll 11 is detected by the monitor sensor 26 and accordingly signals the microprocessor controller 21. The microprocessor controller 21 initiates a process similar to the method just described to reduce the vertical force applied at the retard nip 12, which allows the sheet to pass freely.

3 and 4 are flow diagrams showing the operation of the sheet feeding system according to the present invention. The process is, for example, by the operator pressing the copy button,
It begins when you start a duplication session. The controller of the copying machine sets the feeding error counter and the multi-sheet feeding counter to zero, and sets the jam flag to off (19). The weight of the sheets fed from the stack is then determined and the optimal retarded amount is retrieved from the retard roll height initialization and look-up table (20). Seat weight determination is accomplished, for example, using operator input or current default values. The jam flag is queried (25) to determine if the last three feeds are near misfeed or near multiple feeds, and Indicates that the default weight settings should be adjusted. If the jam flag disappears, the controller sets the retard roll height to the initial setting retrieved by seat weight (60).
Alternatively, the controller determines whether the displayed jam condition was caused by a condition (26) near a continuous feed error or a condition (27) near a continuous multiple feed. By repeating the near misfeed condition, the controller raises the retard roll by the optimum step change retrieved for the corresponding sheet weight (30). Further, the retard roll is lowered by the same optimum step change amount by repeating the state similar to the multi-sheet feeding (50). If neither a near feeding error nor a near multiple feeding condition is indicated, the control signal sends an error signal and stops the function (40). Once the retard roll height is set to either an initial setting or an adjusted setting, the controller sends a signal to the sheet feeder to feed the sheet (70). .

After the sheet feeder receives the signal (70), the controller monitors (80) a motion sensor associated with the retard roll. If the monitor sensor detects that the slip clutch coupled to the retard roll is turning rearward (85), the controller initiates correction of the multi-feed condition for step 200 (see FIG. 4). To do. Alternatively, the controller resets the multi-feed counter to zero (90) and monitors the misfeed sensor (100). The feeding error sensor is
If no sheet is found in 05), the controller initiates a near feed error correction for step 300 (see FIG. 5). When the misfeed sensor finds a sheet, the controller resets the misfeed counter to zero (110). The above process is then repeated for the next sheet to be fed. FIG. 5 is a flow diagram of a process used to correct a near multi-feed condition in accordance with the present invention. The controller checks if the retard roll height is already at the minimum height (205). In that case, the controller signals an error and shuts down (210) the system. Alternatively,
The controller determines the weight of the sheets to be fed (2
20) Lower the retard roll (240) by searching for the optimal step change (230). This will reduce the retard nip normal force on the sheet. The determination of the sheet weight (220) is based on preset default values, operator input, or an opacity sensor that monitors the sheet as it is fed from the stack. Multi-sheet feeding counter (250)
After stepping (250), the control device checks whether the multi-sheet counter is equal to a predetermined maximum value (25).
5) Then, when the maximum value is reached, the jam flag is set to ON (260). The process is then continued (299) with the next sheet to be fed, as described above with reference to FIGS. 3 and 4.

FIG. 6 is a flow diagram of a process for correcting a condition near a feeding error according to the present invention. The controller is
First check (305) if the retard roll is already at maximum height. If so, the controller signals the error and shuts down the system (3
10) Let it do. Alternatively, the controller determines (320) the weight of the seat by the method described above in step 220.
Then, the retard roll is raised to the searched optimum stepwise change amount (330) (340). This increases the retard nip normal force on the sheet. The controller then monitors the misfeed sensor (350) to determine if the correct actuation will cause the sheet to be fed. If the sheet is still not detected (355), the controller raises the retard roll height again. This process continues until the sheet is successfully fed or the retard roll is at its maximum height. When a sheet is fed, the controller increments the feeding error counter (360), checks if the counter is equal to a predetermined maximum value (365), and reaches the maximum value (370). ), Set the jam flag to zero. The controller then monitors the misfeed sensor so that the leading edge of the sheet to be fed passes through the sensor (37).
5) Determine whether or not. The tip of the sheet is the sensor (37
If 5) is passed, the process continues with the next sheet to be fed, as described above with reference to FIGS. 3 and 4. If the leading edge does not pass, it means that the sheet is in the sheet feeder and the controller issues an error signal to shut down (380) the system.

Examples of copying machines to which the present invention is particularly applicable include Xerox model 5046 and Xerox model 50.
28 and Xerox model 5034. The present invention is
These examples are for illustration only, as they are applicable to many different types of copying machines. Although the present invention has been described with reference to detailed embodiments, it will be appreciated by those skilled in the art that many variations and modifications can be made. Therefore, the present invention includes all modifications and variations within the spirit and scope of the claims and equivalents.

[Brief description of drawings]

FIG. 1 is a conventional feed roll sheet feeder known in the prior art.

FIG. 2 is an example of a sheet feeding apparatus according to the present invention.

FIG. 3 is a method of operating a sheet feeding system according to the present invention.

FIG. 4 is a method of operating the sheet feeding system according to the present invention.

FIG. 5 is a method for correcting a state close to a feeding error according to the present invention.

FIG. 6 is a method for correcting a state near multi-sheet feeding according to the present invention.

[Code]

 8 Feeding Roll 9 Sheet Stack 10 Feeding Roll 11 Retard Roll 12 Retard Nip 13 Spring Energizing Mechanism 14 Feeding Miss Sensor 15 Sheet Passage 16 Slip Clutch 17 Sheet 21 Microprocessor Control Unit 22 Opacity Sensor 23 Memory 24 User Interface

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kathleen M. Martin, New York, USA 14464 Hamlin Sandy Shore Drive 6968 (72) Inventor Russell Jay Sokaku, New York, USA 14624 Rochester Tyler Terrace 5 (72) Inventor, Lloyd Duffy United States New York 14522 Palmyra Yellow Mills Road 1180 (72) Inventor Gerald M. Garavuso United States New York 14625 Rochester Savannah Court 14 (72) Inventor Robert Piegel United States New York 14526 Penfield Woodside Drive 52 (72) Inventor Steven Lumpur Moore United States, New York 14623 Rochester Galway DRIVE 143

Claims (1)

[Claims] 1. A feeding means capable of applying a selectively changeable driving force to a sheet in a direction of a sheet passage, and (b) a feeding means coupled to the feeding means. A vertical force mitigating means for altering the selectively changeable driving force applied by: (c) a data accumulator for associating a value of a selected characteristic of the seat with the setting of the vertical force mitigating means; ) Determining the value of the selected characteristic of the sheet to be conveyed, retrieving the corresponding setting of the vertical force reducing means from the data storage, and processing the vertical force reducing means for the corresponding setting. A sheet feeding device for transporting a sheet from a stack to a sheet path, the control device coupled to the vertical force reducing means and the data storage section.