JP2001341894A - Paper feeder and image forming device comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of clarifying a timing to exchange a feed roller or retard roller pair, and an image forming device comprising the same. SOLUTION: Sheets fed out from a feeding means 1 are separated and conveyed one by one by the retard roller pair composed of the feed roller 2 and the retard roller 3 rotating in the direction opposite to the rotating direction of the feed roller 2, and the sheets S1 passed between the retard roller pair are successively detected by two sheet detecting means 10 and 11 mounted at a downstream side of the retard roller pair. A judging means judges the service life of the feed roller 2 by detecting a speed of the sheet S1 passed through the retard roller pair on the basis of a time from the detection of the sheet by the upstream side sheet detecting means 10 to the detection of the sheet S1 by the downstream side sheet detecting means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder and an image forming apparatus provided with the same, and more particularly to a sheet feeder in which sheets are separated and fed one by one using a pair of retard rollers.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as an LBP or a copying machine is provided with a sheet feeding device for feeding a sheet to an image forming section. Alternatively, there is a printer having a feeding roller for feeding the uppermost sheet stacked on the sheet stacking tray, and a separating unit for separating the sheets fed by the feeding roller one by one.

Further, the separating means includes a feed roller which rotates in the same direction as the feed roller, and a retard roller which rotates in the opposite direction to the feed roller, and a plurality of sheets are rotated by the feed roller. If sent,
By using a retard roller to return sheets other than the top sheet to the sheet stacking cassette or sheet stack tray, only the top sheet can be fed to the image forming unit. Has been

FIG. 8 is a view showing the structure of such a conventional retard roller type separating means. In FIG.
Reference numeral 1 denotes a feed roller serving as a feeding means, and reference numeral 2 denotes a feed roller which is provided on the downstream side of the feed roller 1 in the sheet feeding direction and rotates in the sheet S feeding direction similarly to the feed roller 1.

Reference numeral 3 denotes a retard roller, which is disposed so as to be able to contact and separate from the feed roller 2 and which has a torque (not shown) with respect to a retard shaft 4 which rotates in a direction opposite to the direction in which the sheet S is fed. They are connected via a limiter unit. In addition, this retard roller 3
Before the feeding operation is started, the feeding roller 2 is pressed against the feed roller 2 with a predetermined pressure by an urging means (not shown).

Here, the pressing force for pressing the retard roller 3 against the feed roller 2 is determined when the retard roller 3 is in contact with the feed roller 2 and when the sheet S is between the feed roller 2 and the retard roller 3. When only one sheet is fed, the retard roller 3 is
While rotating forward in the direction in which the sheet S is sent out,
The pressure is set such that the retard roller 3 rotates integrally with the retard shaft 4 when two or more sheets S are fed between the feed roller 2 and the retard roller 3.

Therefore, when two or more sheets S are fed between the feed roller 2 and the retard roller 3,
As shown in the figure, the uppermost sheet S1 is fed by the feed roller 2, while the other sheets S2 are returned to the sheet storage unit 15 by the retard roller 3.

On the other hand, when the retard roller 3 is rotated in the reverse direction and the sheet S2 other than the uppermost sheet S1 is conveyed in the direction opposite to the sheet feeding direction, the feeding roller 1 does not touch the sheet S. Is moving upwards. This allows
The other sheet S2 can be returned to the original position without being disturbed by the feeding roller 1.

In such a retarding roller type separating means, the feeding roller 1 and the retarding roller 3 of the uppermost sheet S1 of the stacked sheets S are used for the purpose of keeping the sheet feeding and separating performance constant. It is common practice to provide a seat height adjustment mechanism for adjusting the height of the seat to a constant value.

By the way, in such a retard roller type separating means, when the feeding force of the feed roller 2 is reduced due to abrasion or the like, the feed roller 1 sends out the sheet S1 and then moves upward. As shown in (1), there is a possibility that the sheet S1 cannot be conveyed and a paper feed failure occurs.

On the other hand, FIG. 10 is a view showing the structure of another conventional separating device of the retard roller type. In this case, the feeding roller 1 has the arm member 5 rotatable about a shaft 6. It is rotatably attached to one end. The sheet feed roller 1 is located downstream of the shaft in the sheet feeding direction.
1 is in contact with the upper surface.

Here, the arm member 5 is rotated downward by its own weight or by urging means (not shown), so that the feeding roller 1 is always in contact with the sheet S regardless of the amount of the sheet S stacked. Further, a gear or the like (not shown) is built in the arm member 5, and driving from a driving source (not shown) is transmitted to the feed roller 1 through the gear or the like. The rotation speed of the feed roller 1 is set to be lower than that of the feed roller 2.

[0013]

By the way, in such a conventional sheet feeding apparatus using the retard roller type separating means, the sheet S cannot be conveyed due to a decrease in the conveying force of the feed roller 2. In this case, since the feed roller 1 is always in contact with the sheet as shown in FIG. 11, no paper feed failure occurs. However, the feed roller 2 and the retard roller 3 whose conveyance force has been reduced due to the service life have been used. The nip portion of the retard roller pair causes the sheet conveyance resistance.

Here, the sheet feeding pressure generated on the uppermost sheet S1 when the sheet is conveyed by the feed roller 1 using the arm member 5 is determined by the biting force of the feed roller 1 as the sheet conveyance resistance increases. Becomes larger in proportion to the sheet resistance, so that when the sheet conveyance resistance increases due to a decrease in the conveying force of the feed roller 2,
The paper feed pressure of the feed roller 1 becomes larger than necessary. When the sheet feeding pressure becomes unnecessarily large, there is a possibility that the motor loses synchronism due to the double feed or an increase in the load torque of the drive motor.

Therefore, in order to prevent the occurrence of such a double feed or loss of synchronism of the motor, the feed roller 2 or the pair of retard rollers may be replaced before the conveying force of the feed roller 2 is reduced due to its life. However, since the appropriate roller replacement time is not known, the roller cannot be replaced even if the feed roller 2 approaches the end of its life. For this reason,
Double feed and motor loss of synchronization may occur.
As described above, in the separating means having the configuration shown in (1), there is a possibility that a paper feeding failure jam occurs.

The present invention has been made in view of such circumstances, and provides a paper feeder capable of clarifying the time for replacing a feed roller or a retard roller pair, and an image forming apparatus having the same. The purpose is to do so.

[0017]

According to the present invention, there is provided a paper feeder for separating and feeding a sheet sent by a feeding means one by one, comprising: a feed roller for feeding the sheet fed by the feeding means; A retard roller that rotates in a direction opposite to the rotation direction of the feed roller, and a pair of retard rollers that separates and conveys the sheets fed by the feeding unit one by one, and a pair of retard rollers downstream of the pair of retard rollers. Two sheet detecting means for sequentially detecting sheets passing through the pair of retard rollers, and a time period between when the sheet detecting means on the upstream side detects the sheet and when the sheet detecting means on the downstream side detects the sheet. A timer that counts time, and a determiner that determines the life of the feed roller based on timing information from the timer. Is shall.

Further, according to the present invention, the judging means detects the speed of the sheet passing through the retard roller pair from the timing information from the timing means and the distance between the two sheet detecting means, and detects the detected sheet. The life of the feed roller is determined by comparing the speed of the feed roller with a predetermined set value.

Further, according to the present invention, the sheet conveying speed of the feed roller is set to be faster than the sheet conveying speed of the feeding unit, and the predetermined set value is set as the sheet conveying speed of the feeding unit. The determining means determines that the feed roller has reached the end of its life when the detected speed of the sheet passing through the retard roller pair is equal to or lower than the sheet conveying speed of the feeding means. Things.

Further, according to the present invention, the distance between the two sheet detecting means is L (mm), the sheet conveying speed of the feed roller is Vf (mm / s), and the sheet conveying speed of the feed roller is Vp (mm). / S), the predetermined set value T is: T = L / Vf + 0.8 (L / Vp-L / Vf).

Also, the present invention counts the number of times the detected speed of the sheet passing through the retard roller pair is equal to or slower than a predetermined set value, and when the number of times is larger than the predetermined number, This is characterized in that the life of the feed roller is determined.

According to the present invention, the feeding means is attached to an arm supported swingably by a shaft, and is arranged so as to abut on a sheet at a downstream side of the shaft in a sheet feeding direction. It is characterized by the following.

According to the present invention, there is provided an image forming apparatus including an image forming unit and a sheet feeding device for feeding a sheet to the image forming unit, wherein the sheet feeding device is any one of the above. It is characterized by the following.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an image forming apparatus provided with a sheet feeding device according to an embodiment of the present invention. In addition,
In the figure, the same reference numerals as those in FIG. 10 indicate the same or corresponding parts.

In FIG. 1, reference numeral 20 denotes an image forming apparatus provided with an electrophotographic image forming unit (not shown), for example. Is attached.

The paper feed deck 21 is provided with a storage 8 for storing print paper S, which is a sheet. The storage 8 is attached to the apparatus main body 21a so as to be able to be pulled out. When replenishing the print paper S, the storage 8 is pulled out along the guide rail 23 to the front side of the apparatus main body and supplied. ing.

The print paper S is provided above the storage 8.
A feed roller 1 is provided which rotates forward in the direction in which the paper is fed out. The feed roller 1 is rotatably supported by one end of an arm member 5 which is swingably supported by a shaft 6.
The feed roller 1 is provided so as to be able to contact the print sheet S downstream of the shaft 6 in the sheet feeding direction.

On the other hand, in FIG.
The print paper loading table 9 is configured such that when the storage 8 is pulled out to the front side of the apparatus body and the print paper S is loaded, the storage 8 is stored.
The ascending / descending means (not shown) ascends.

After that, the printing paper loading table 9 is
The uppermost surface of the stacked print papers S rises to a predetermined height fed by the feed roller 1, and stops when a paper surface detection unit (not shown) detects this.

After stopping in this manner, the printing paper stacking table 9 is held by the paper surface detecting means so that the uppermost surface of the printing paper S is always maintained at a predetermined height fed by the feeding roller 1. Accordingly, the sagging angle of the arm member 5 when the feeding roller is driven is always constant regardless of the load amount.

Reference numeral 7 denotes a pair of conveying rollers, and the pair of conveying rollers 7 is, as shown in FIG.
The feed roller 2 is disposed downstream of the sheet conveying (feeding) direction and rotates forward in the feed direction of the print sheet S. And the retard roller 3 that rotates in the direction of paper transport of the pair of retard rollers.

In this embodiment, the paper transport speed of the feed roller 1 is set lower than the paper transport speed of the feed roller 2.

Next, the sheet feeding deck 2 constructed as described above
1 will be described.

When the paper feeding operation is started, the feed roller 1 rotates in the forward direction, and the uppermost print paper S1 of the print paper S on the print paper loading table is fed to the nip portion between the feed roller 2 and the retard roller 3. Feed to

When only the uppermost print sheet S1 is fed to the nip between the feed roller 2 and the retard roller 3 at this time, the print sheet S1 is conveyed by the feed roller 2 rotating in the forward direction in the feed direction. The sheet is fed to the roller pair 7. At this time, the retard roller 3 is normally rotated in the feed direction of the print paper S1 following the feed roller 2.

On the other hand, when two or more print papers S are fed to the nip between the feed roller 2 and the retard roller 3, the uppermost print paper S1 is fed by the feed roller 2 that rotates forward in the feed direction. In this direction, the print paper S other than the topmost print paper, ie, the second and subsequent print papers S, is fed to the feed roller pair 7 by the retard roller 3 which rotates in the reverse direction with respect to the feed direction. Transported in the opposite direction and returned to the print paper loading table.

As a result, the printing paper S is surely separated one by one from the uppermost printing paper S1 and then transported by the transport roller pair 7 to the image forming apparatus 20 installed on the paper feed deck. Then, an image is formed in the image forming apparatus main body.

By the way, between the feed roller 2 and the retard roller 3 and the conveying roller pair 7, two sheet detections for detecting the uppermost print sheet S1 sent out by the feed roller 2 as shown in FIG. First and second sensors 10 and 11 as means are provided. Here, the first sensor 10 is provided in the vicinity of the nip between the feed roller 2 and the retard roller 3, and the second sensor 1
Reference numeral 1 is arranged near the pair of transport rollers 7.

The first and second sensors 10, 10
Reference numeral 11 denotes ON when the print sheet S1 is detected, and turns OFF when the rear end of the sheet passes. The outputs of the first and second sensors 10 and 11 are input to a control device 30 as shown in FIG. The time T during which the print paper S1 moves from the first sensor 10 to the second sensor 11 as shown in FIG.
Is detected by the timer 32 which is a time measuring means shown in FIG.

Here, the paper transport speed when the print paper S1 is fed by the feed roller 2 is Vf (mm / mm).
s) The paper transport speed when the paper is fed by the feed roller 1 is Vp (mm / s). This feed roller 2
Paper transport speed Vf and paper transport speed Vp of feed roller 1
Is Vf> Vp as described above.

Assuming that the distance between the first and second sensors 10 and 11 is L (mm), the time T during which the print paper S1 moves from the first sensor 10 to the second sensor 11 is represented by T
Is L when the feed roller 2 has not reached the end of its life.
/ Vf.

On the other hand, when the feed roller 2 is worn or the like,
In other words, when the transport force is reduced due to the service life and the print paper S1 cannot be transported, the print paper S1 is transported by the feed roller 1, and the movement time T in this case is L / Vp.

Here, since Vf> Vp, the moving time T when the conveying force of the feed roller 2 is not decreased is shorter than the moving time when the conveying force of the feed roller 2 is decreased. Become. Therefore, if the movement time T is detected, it is possible to determine a decrease in the conveying force of the feed roller 2, that is, the life. Further, when it is determined that the feed roller 2 has reached the end of its life, by displaying this, it is possible to clarify the time for replacing the feed roller 2 or the retard roller pair.

Next, the sheet feeding deck 2 constructed as described above
1 will be described with reference to the flowchart shown in FIG.

When the paper feeding operation is started, the control device 30, which is a determining means for determining the life of the feed roller 2, drives the paper feeding motor 31 to rotate the feed roller 1 and the feed roller 2 (S50). . And after this, the first
When the sensor 10 is turned on (Y in S51), the timer 32
Is started (S52), and then the second sensor 10 is turned on.
It is determined whether or not (S53).

When the second sensor 10 is turned on (Y in S53), the timer 32 is stopped (S5).
4) At this time, the timing information of the timer 32, that is, the time T during which the print sheet S1 moves from the first sensor 10 to the second sensor 11, and the print sheet S1 is conveyed by the feed roller 1, which is a predetermined set value. Moving time L / Vp
Compare with

If the feed roller 2 is not worn, T = L / Vf and Vf> Vp, so that T <L / Vp (N in S55). And
In such a case, it is determined that the life of the feed roller 2 has not reached the end of its life, and thereafter the paper feed motor 31 is stopped (S5).
6).

On the other hand, when the feed roller 2 is worn, the transport force of the feed roller 2 is reduced, and the transport speed is reduced, and eventually T ≧ L / Vp (Y in S55). In this case, it is determined that the life of the feed roller 2 has reached the end of its life, and thereafter the paper feed motor 31 is stopped (S57).
At the same time, a display for instructing replacement of the retard roller pair or the feed roller 2 is performed on the display device 33 (S5).
8).

In consideration of the peripheral speed error of the feed roller 1, the comparison formula in S55 is, for example, the following formula, that is, the predetermined set value is set to Vf + 0.8.
By setting (L / Vp−L / Vf), the life of the feed roller 2 can be more accurately determined.

T ≧ L / Vf + 0.8 (L / Vp−L / Vf) In the above equation, 0.8 is a value determined based on an error in the peripheral speed of the feeding roller 1.

By displaying on the display device 33 that the feed force of the feed roller 2 is reduced due to the service life and the print paper S cannot be fed, the user can change the roller at an appropriate time. Accordingly, it is possible to prevent the double feed due to the life of the feed roller 2 and the step-out of the motor from occurring.

Note that the second sensor 10 is not turned on (S
If the predetermined time has elapsed (N in S53), it is determined that a jam has occurred, the timer 32 is stopped (S71), and the paper feed motor 31 is stopped (S72). Then, jam display is performed by the display device 33 (S73).

As described above, by determining the life of the feed roller 2 by detecting the transport speed of the printing paper S1 passing through the retard roller pair, the roller can be replaced at an appropriate time. Of the double feed and motor step-out due to the life of the motor can be prevented.

As described above, the life of the feed roller 2 can be determined by comparing T with L / Vp. However, the life of the feed roller 2 is still small due to erroneous detection or malfunction of the feed roller 2. , The controller 30 may determine the life of the feed roller 2 and display it on the display unit 33.

In order to prevent such erroneous detection, T ≧
By determining that the transport force of the feed roller 2 has decreased only when L / Vp is detected a plurality of times during feeding of a predetermined number of print sheets, the roller can be replaced at a more appropriate time.

Next, the feed roller life determining operation of the sheet feeding device (sheet feeding deck) according to another embodiment of the present invention will be described with reference to the flowchart shown in FIG.

In the figure, portions that are the same as those in the flow chart shown in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the transport force of the feed roller 2 is reduced and the paper S cannot be transported, and the paper S is transported by the feed roller 1 so that T ≧ L / V
p or T ≧ L / Vf + 0.8 (L / Vp−L / V
It is controlled to count the number of times f).

That is, when T ≧ L / Vp (Y in S55), the controller 30 counts this number to the counter 34 (FIG. 4).
(See S60). If the number of times counted by the counter in this way while feeding the predetermined number of print papers, in other words, the counted number exceeds a certain value (Y in S61), the life of the feed roller 1 reaches the end of its life. Is determined to be unable to convey the print paper S, and the paper feed motor 31 is stopped (S
At the same time as 62), a display for instructing replacement is displayed on the display device 33 (S63).

If the ratio counted by the counter does not exceed a certain value (N in S61), it is determined that the life of the feed roller 1 has not reached the end of its life, and the paper feed motor 31 is stopped (S64). ).

As described above, T ≧ L / Vp or T ≧ L /
When Vf + 0.8 (L / Vp-L / Vf) is detected a plurality of times during feeding of a predetermined number of print sheets (in the present embodiment, when the counted ratio exceeds a certain value) By displaying the replacement instruction in ()), it is possible to prevent the replacement instruction from being displayed even though the feed roller 2 has not reached the end of its life.

[0063]

As described above, according to the present invention, the life of the feed roller is determined by detecting the conveying speed of the sheet passing through the retard roller pair, so that the replacement time of the feed roller or the retard roller pair is determined. Can be clarified. As a result, it is possible to prevent double feed and loss of synchronism of the motor due to the life of the feed roller.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a structure of an upper portion of a sheet feeding deck as the sheet feeding device.

FIG. 3 is a side view showing a configuration of a pair of retard rollers of the paper feeding deck.

FIG. 4 is a control block diagram of a feed roller life determining operation of the paper feeding deck.

FIG. 5 is a diagram illustrating an operation of determining the life of the feed roller.

FIG. 6 is a flowchart illustrating a feed roller life determining operation.

FIG. 7 is a flowchart illustrating an operation of determining the life of a feed roller in a sheet feeding apparatus according to another embodiment of the present invention.

FIG. 8 is a diagram showing the configuration of a conventional retard roller type separation unit.

FIG. 9 is a diagram illustrating a state where the conveying force of a feed roller in the conventional separation unit is reduced.

FIG. 10 is a diagram showing a configuration of another conventional retard roller type separation unit.

FIG. 11 is a diagram showing a state in which the conveying force of the feed roller in the other conventional separation unit is reduced.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 feed roller 2 feed roller 3 retard roller 5 arm member 7 transport roller pair 10 first sensor 11 second sensor 30 control device 32 timer 33 display device 34 counter S print paper

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Kawanishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takashi Kuwata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Akira Matsushima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Makoto Izumi 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. F Terms (reference) 3F048 AA01 AB01 BA11 BB02 BB05 CC01 CC11 CC12 CC17 DA04 DB04 DB07 DB12 EB12 3F343 FA02 FB01 FC22 GA01 GB01 GC01 GD01 JA01 JD09 JD34 MA41 MA45 MA54 MA58 MC28

Claims (7)

[Claims] 1. A sheet feeding device for separating sheets fed by a feeding means and feeding the separated sheets one by one, comprising: a feed roller for conveying the sheets fed by the feeding means; and a rotation direction of the feed roller. A retard roller pair that rotates in the opposite direction and separates and conveys the sheet sent by the feeding unit one by one; and a retard roller pair provided downstream of the retard roller pair, Two sheet detecting means for sequentially detecting a passing sheet; and a timing means for measuring a time from when the sheet detecting means on the upstream side detects the sheet to when the sheet detecting means on the downstream side detects the sheet. A determination unit configured to determine a life of the feed roller based on timing information from the timing unit. 2. The method according to claim 1, wherein the determining unit detects a speed of the sheet passing through the pair of retard rollers based on timing information from the timing unit and a distance between the two sheet detecting units. 2. The paper feeder according to claim 1, wherein the life of the feed roller is determined by comparing the feed roller with a predetermined set value. 3. The sheet conveying speed of the feed roller is set to be higher than the sheet conveying speed of the feeding unit, and the predetermined set value is set as the sheet conveying speed of the feeding unit. The means determines that the feed roller has reached the end of its life when the detected speed of the sheet passing through the retard roller pair is equal to or slower than the sheet conveyance speed of the feeding means.
Paper feeder as described. 4. The distance between the two sheet detecting means is L.
(Mm), the sheet conveying speed of the feed roller is Vf
(Mm / s), the sheet conveying speed of the feed roller is Vp
3. The sheet feeding device according to claim 2, wherein, when (mm / s) is set, the predetermined set value T is: T = L / Vf + 0.8 (L / Vp-L / Vf). 5. A method for counting the number of times that the speed of a sheet passing through the detected retard roller pair is equal to or lower than a predetermined set value, and when the number of times is greater than the predetermined number, The paper feeder according to claim 3, wherein the life of the paper is determined. 6. The apparatus according to claim 1, wherein the feeding unit is attached to an arm supported by a shaft so as to be swingable, and is arranged so as to abut on a sheet downstream of the shaft in a sheet feeding direction. The sheet feeding device according to any one of claims 1 to 5, wherein: 7. An image forming apparatus comprising: an image forming unit; and a sheet feeding device for feeding a sheet to the image forming unit, wherein the sheet feeding device is the one according to any one of claims 1 to 6. An image forming apparatus, comprising: