US20200017324A1

US20200017324A1 - Sheet separation using pressing force

Info

Publication number: US20200017324A1
Application number: US16/540,624
Authority: US
Inventors: Eiji Aoki; Jin Soo Lee
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2017-03-03
Filing date: 2019-08-14
Publication date: 2020-01-16
Also published as: CN110392661A; KR20180101054A; WO2018159936A1; CN110392661B; EP3529184A1; EP3529184A4

Abstract

A sheet separation device includes a separating member to contact a feed roller and to separate sheet-type media transported between the feed roller and the separating member, the separating member movable to contact the feed roller at a plurality of contact points on the feed roller along the withdrawing direction to apply different pressing forces corresponding to the plurality of contact points.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of PCT International Application No. PCT/KR2018/000248, filed on Jan. 5, 2018, which claims the priority benefit of Korean Patent Application No. 10-2017-0027777, filed on Mar. 3, 2017, the contents of the PCT International Application and the Korean Patent Application are incorporated by reference herein in their entirety.

BACKGROUND

Apparatuses, such as printers, scanners, and ticketing machines, using a sheet-type medium, for example, a cut sheet (hereinafter, referred to as paper, or piece(s) of paper, or sheet(s) of paper), use a sheet separation device that feeds one sheet at a time from a load tray on which a plurality of sheets are placed.
The sheet separation device separates paper to be fed one sheet at a time using difference(s) in frictional forces between a feed roller, paper, and a separating member while the paper passes between the feed roller and the separating member contacting the feed roller.
A frictional force depends on a normal force between the feed roller and the separating member, and friction coefficients between the feed roller and the paper, a sheet of the paper and another sheet of the paper, and the paper and the separating member. If the normal force is strong, the chance of miss-feeding and the chance of abrasion of the feed roller and/or the separating member may decrease, while the chance of multi-feeding of more than one sheet of the paper may increase. On the other hand, if the normal force is weak, the chance of multi-feeding may decrease, while the chance of miss-feeding and the chance of abrasion of the feed roller and/or the separating member may increase.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readily appreciated from the following description of the examples, taken in conjunction with the accompanying drawings in which:

FIG. 1A is a schematic configuration diagram of a sheet separation device according to an example;

FIG. 1B is a schematic side view of the sheet separation device of FIG. 1a according to an example;

FIG. 2 is a diagram of an active retard roller structure according to an example;

FIG. 3 is a diagram of a semi-active retard roller structure according to an example;

FIG. 4A is a diagram of a separating member in a first location, according to an example;

FIG. 4B is a diagram of the separating member in a second location, according to an example;

FIG. 4C is an operating diagram of a separating unit, according to an example;

FIGS. 5A to 5E are diagrams of operations of a sheet separation device in a case in which no paper or only one piece of paper is guided between a feed roller and a separating member, according to an example;

FIGS. 6A to 6C are diagrams of operations of a sheet separation device in a case in which at least two pieces of paper are guided between a feed roller and a separating member, according to an example;

FIG. 7 is a schematic configuration diagram of a sheet separation device according to an example;

FIG. 8 is a perspective view of an implementation example of a structure whereby a separating member may move to first and second locations, according to an example;

FIG. 9 is a diagram of a sheet separation device including a guide member, according to an example;

FIG. 10 is a perspective view of an implementation example of a structure whereby a separating member may move to first and second locations;

FIG. 11 is a schematic configuration diagram of a sheet separation device according to an example;

FIG. 12 is a block diagram of a sheet processing apparatus including a sheet separation device, according to an example;

FIG. 13 is a schematic configuration diagram of a scanner including a sheet separation device, according to an example;

FIG. 14 is a schematic configuration diagram of an image forming apparatus including a sheet separation device, according to an example; and

FIG. 15 is a schematic diagram of a multifunctional apparatus according to an example.

DETAILED DESCRIPTION

Hereinafter, examples of a sheet separation device and a sheet processing apparatus using the same will be described with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout, and size or thickness of each element may be exaggerated for clarity of description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
FIG. 1A is a schematic configuration diagram of a sheet separation device 1 according to an example. FIG. 1B is a schematic side view of the sheet separation device 1 of FIG. 1A according to an example.
Referring to FIGS. 1A and 1B, the sheet separation device 1 includes a load tray 10 on which sheet-type media, for example, cut sheets (hereinafter, referred to as paper, or piece(s) of paper, or sheet(s) of paper) P, are placed, and a pickup roller (pickup member) 20 that picks up the pieces of paper P placed on the load tray 10. The pickup roller 20 contacts, for example, paper P1, which is at the top from among the pieces of paper P placed on the load tray 10. A pickup member is not limited to a roller type, and may be any of various types such as a belt type.
The pickup roller 20 may be connected to a feed roller 31, for example, by a belt. When the pickup roller 20 rotates, the paper P1 is picked up and guided or transported out of the load tray 10. In some cases, the paper P1 and at least one piece of paper P2 below the paper P1 may be guided or transported out together, which is referred to as multi-feeding.
The sheet separation device 1 further includes a separating unit for separating and transporting only one piece of paper, for example, the paper P1, when multi-feeding occurs. The separating unit may have various structures such as an active retard roller structure, a semi-active retard roller structure, or a retard pad structure. The separating unit includes the feed roller 31 and a separating member 32 to contact or contacting the feed roller 31. An elastic member 35 a is to apply or applies an elastic force (first elastic force) in a direction of the separating member 32 contacting the feed roller 31.
FIG. 2 is a diagram of an active retard roller structure according to an example. Referring to FIG. 2, the separating member 32 is an active retard roller that is to contact or contacts the feed roller 31. The feed roller 31 and the separating member 32 rotate in mesh with each other. The feed roller 31 rotates in a first direction B1 for transporting the pieces of papers P in a withdrawing direction A1. The separating member 32 rotates in a second direction B2 for transporting the pieces of papers P in a direction A2 opposite to the withdrawing direction A1. A driving member, for example, a driving gear 34, provides a driving force in the second direction B2 to the separating member 32. Besides a gear, various power transmission members such as a belt may be used as the driving member.
A torque limiter 33 provides a threshold torque whereby driven rotation of the separating member 32 by the feed roller 31 starts. That is, the torque limiter 33 selectively allows driven rotation of the separating member 32 by the feed roller 31 according to a size of a load torque applied to the separating member 32. When the load torque applied to the separating member 32 exceeds the threshold torque provided by the torque limiter 33, the driving force in the second direction B2 transmitted to the separating member 32 is blocked by the torque limiter 33, and the separating member 32 is allowed to be driven by the feed roller 31 to rotate in a third direction B3. When the load torque applied to the separating member 32 is less than the threshold torque provided by the torque limiter 33, the separating member 32 is rotated in the second direction B2 by the driving force of the driving gear 34.
The torque limiter 33 may have various well-known structures. For example, the torque limiter 33 may be implemented by a spring clutch structure. The separating member 32 is installed at a supporting shaft 321 and engages with the feed roller 31. When the supporting shaft 321 and the separating member 32 are integrally formed with each other, or the separating member 32 is fixed to the supporting shaft 321, the supporting shaft 321 and the driving gear 34 are connected to each other by the torque limiter 33. For example, a clutch spring (not shown) may be inserted into the supporting shaft 321 or a hub fixed to the supporting shaft 321, and a predetermined threshold torque may be provided by a clamping force thereof. The driving gear 34 provides a driving force in the second direction B2 to the clutch spring. When a load torque applied to the supporting shaft 321 is less than a threshold torque, the supporting shaft 321 rotates in the second direction B2. When the load torque applied to the supporting shaft 321 is greater than the threshold torque, the clutch spring loosens, thereby blocking the driving force of the driving gear 34.
When the separating member 32 is rotatably installed at the supporting shaft 321, the supporting shaft 321 and the separating member 32 are connected to each other by the torque limiter 33. For example, a clutch spring (not shown) may be inserted into the supporting shaft 321 or a hub fixed to the supporting shaft 321, and a predetermined threshold torque may be provided by a clamping force thereof. An end portion of the clutch spring may be connected to the separating member 32. The driving gear 34 is fixed to the supporting shaft 321 and rotates the supporting shaft 321 in the second direction B2. When a load torque applied to the separating member 32 is less than a threshold torque, the separating member 32 rotates in the second direction B2. When the load torque applied to the separating member 32 is greater than the threshold torque, the clutch spring loosens, thereby blocking driving connection between the supporting shaft 321 and the separating member 32.
A separating operation according to such a structure will now be briefly described.
When no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32, a load torque applied to the separating member 32 is greater than a threshold torque of the torque limiter 33, and thus, the torque limiter 33 blocks a driving force toward the separating member 32. Accordingly, the separating member 32 rotates in the third direction B3 for transporting the pieces of papers P in the withdrawing direction A1 in cooperation with the feed roller 31.
When at least two pieces of paper P, for example, the paper P1 and the paper P2, are guided between the feed roller 31 and the separating member 32, the paper P1 and the paper P2 contact the feed roller 31 and the separating member 32, respectively. In this regard, a frictional force between the paper P1 and the paper P2 is less than a frictional force between the paper P2 and the separating member 32. Thus, a slip occurs between the paper P1 and the paper P2, and a load torque applied to the separating member 32 is less than a threshold torque provided by the torque limiter 33. The separating member 32 rotates in the second direction B2, and the paper P2 is transported in the direction A2 opposite the withdrawing direction A1 by the separating member 32. Accordingly, only the paper P1 passes between the feed roller 31 and the separating member 32 and is transported in the withdrawing direction A1.
FIG. 3 is a diagram of a semi-active retard roller structure according to an example. Referring to FIG. 3, the separating member 32 is a semi-active retard roller that contacts the feed roller 31. The semi-active retard roller structure is different from the active retard roller structure in that a driving force in the second direction B2 is not provided to the separating member 32.
The feed roller 31 rotates in the first direction B1 for transporting the pieces of paper P in the withdrawing direction A1. The separating member 32 is rotatably installed at the supporting shaft 321. The separating member 32 is connected to the supporting shaft 321 by the torque limiter 33. The separating member 32 is driven by the feed roller 31 to rotate in the third direction B3.
The torque limiter 33 selectively allows rotation of the separating member 32 according to a size of a load torque applied to the separating member 32. When the load torque applied to the separating member 32 exceeds a threshold torque provided by the torque limiter 33, the torque limiter 33 allows the separating member 32 to be rotated in the third direction B3 by the feed roller 31. When the load torque applied to the separating member 32 is less than the threshold torque provided by the torque limiter 33, the torque limiter 33 does not allow rotation of the separating member 32.
A separating operation according to such a structure will now be briefly described.
When no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32, a load torque applied to the separating member 32 is greater than a threshold torque of the torque limiter 33, and thus, the separating member 32 rotates in the third direction B3 for transporting the pieces of papers P in the withdrawing direction A1 in cooperation with the feed roller 31.
When at least two pieces of paper P, for example, the paper P1 and the paper P2, are guided between the feed roller 31 and the separating member 32, the paper P1 and the paper P2 contact the feed roller 31 and the separating member 32, respectively. In this regard, a frictional force between the paper P1 and the paper P2 is less than a frictional force between the paper P2 and the separating member 32. Thus, a slip occurs between the paper P1 and the paper P2, and a load torque applied to the separating member 32 is less than a threshold torque provided by the torque limiter 33. The separating member 32 does not rotate, and the paper P2 is caught in the separating member 32 to stop without being transported in the withdrawing direction A1. Accordingly, only the paper P1 passes between the feed roller 31 and the separating member 32 and is transported in the withdrawing direction A1.
The sheet separation device 1 separates only one piece of paper P1 by using a difference in frictional forces between the feed roller 31 and the paper P1, the paper P1 and the paper P2, and the separating member 32 and the paper P2. A frictional force depends on a normal force N between the feed roller 31 and the separating member 32, and friction coefficients between the feed roller 31 and the paper P1, the paper P1 and the paper P2, and the paper P2 and the separating member 32. Since the frictional coefficients are determined by materials, the frictional force depends on the normal force N. If the normal force N is strong, the chance of miss-feeding and the chance of abrasion of the feed roller 31 and/or the separating member 32 may decrease, whereas the chance of multi-feeding may increase. On the other hand, if the normal force N is weak, the chance of multi-feeding may decrease, whereas, as the separating member 32 slips without being driven by the feed roller 31, the chance of abrasion of the feed roller 31 and/or the separating member 32 may increase, and the chance of miss-feeding may increase.
Accordingly, when no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32, the normal force N may be increased to decrease the chance of miss-feeding and the chance of abrasion of the feed roller 31 and/or the separating member 32. When at least two pieces of paper P are guided between the feed roller 31 and the separating member 32, the normal force N may be decreased to decrease the chance of multi-feeding.
The normal force N is influenced by a static pressing force Ns due to an elastic force Fs of the elastic member 35 a pressing the separating member 32 toward the feed roller 31, and a dynamic pressing force Nr1 due to a torque Tr1 applied to the separating member 32 by the feed roller 21, and in an active retard mechanism, is additionally influenced by a dynamic pressing force Nr2 due to a torque Tr2 for driving the separating member 32.
That is, in a semi-active retard roller mechanism and a retard pad mechanism,
N=Ns+Nr1 —(Equation 1)
is satisfied, and
in an active retard roller mechanism,
N=Ns+Nr1+Nr2 —(Equation 2)
is satisfied.
Accordingly, the normal force N may be changed by adjusting the elastic force Fs, the torque Tr1, and the torque Tr2.
In order to adjust the elastic force Fs, a detecting device as means of detecting the number of pieces of paper P guided between the feed roller 31 and the separating member 32 and an adjusting device as active means to adjust a length of free field of the elastic member 35 a (or adjusting a location of a supporting portion of the elastic member 35 a) may be required. Also, in order to adjust the torque Tr2, a detecting device as means of detecting the number of pieces of paper P guided between the feed roller 31 and the separating member 32 and an active means for adjusting a reduction gear ratio between a driving motor (not shown) and the separating member 32 may be required.
In the present example, without the detecting device as means of detecting the number of pieces of paper P guided between the feed roller 31 and the separating member 32, a structure in which the normal force N is adjusted according to the number of pieces of paper P guided between the feed roller 31 and the separating member 32 is employed. In the present example, the normal force N is changed by adjusting the dynamic pressing force Nr1 according to the number of pieces of paper P guided between the feed roller 31 and the separating member 32.
Referring to FIG. 1B, the separating member 32 may move to a first location (denoted by solid lines) and a second location (denoted by dashed lines). The second location is at a downstream side of the first location with respect to a rotation direction of the feed roller 31 or in a withdrawing direction of paper P. For example, a holder 36 is rotatable on a hinge 361. The separating member 32 is supported by an end portion of the holder 36. The elastic member (first elastic member) 35 a applies an elastic force so that the holder 36 rotates on the hinge 361 in a direction where the separating member 32 contacts the feed roller 31. The hinge 361 is movable from a location denoted by solid lines in FIG. 1B to a location denoted by dashed lines. A second elastic member 35 b provides an elastic force (second elastic force) in a direction for maintaining the separating member 32 in the first location, that is, a direction for returning from the second location to the first location.
FIG. 4A is a diagram of the separating member 32 in the first location. FIG. 4B is a diagram of the separating member 32 in the second location.
Referring to FIG. 4A, the separating member 32 is placed in the first location. When the feed roller 31 rotates, the torque Tr1 acts on the separating member 32. Owing to the torque Tr1, a force F of Tr1×R acts at a first contact point C1 of the feed roller 31 and the separating member 32. In this regard, R is a radius of the separating member 32. The force F acts in a direction perpendicular to a line L11 connecting a center 32 a of the separating member 32 or the first contact point C1 to a center 31 a of the feed roller 31. Since the separating member 32 is installed capable of rotating on the hinge 361, the force F has a component in a direction of the line L11 and a component in a direction of a line L21 connecting the first contact point C1 to the hinge 361. A first dynamic pressing force Nr11, which is the component of the force F in the direction of the line L11, corresponds to Nr1 of Equations 1 and 2. Nr11 depends on an angle G1 between the line L11 and the line L21.
Referring to FIG. 4B, the separating member 32 is placed in the second location. When the feed roller 31 rotates, the force F acts. The force F acts in a direction perpendicular to a line L12 connecting the center 32 a of the separating member 32 or a second contact point C2 to the center 31 a of the feed roller 31. Since the separating member 32 is installed capable of rotating on the hinge 361, the force F has a component in a direction of the line L12 and a component in a direction of a line L22 connecting the second contact point C2 to the hinge 361. A second dynamic pressing force Nr12, which is the component of the force F in the direction of the line L12, corresponds to Nr1 of Equations 1 and 2.
In this regard, the force F is identical. Nr1 depends on an angle between a first line connecting the center 31 a of the feed roller 31 to the center 32 a of the separating member 32, or a contact point of the feed roller 31 and the separating member 32 to the center 31 a of the feed roller 31, and a second line connecting the contact point of the feed roller 31 and the separating member 32 to the hinge 361. As the angle increases, Nr1 increases. The first angle G1 between the line L11 and the line L21 at the first location is less than a second angle G2 between the line L12 and the line L22 at the second location. Therefore, Nr11 is less than Nr12, and a first normal force at the first location is less than a second normal force at the second location. Accordingly, when one piece of paper P is guided between the feed roller 31 and the separating member 32, the separating member 32 is moved to the second location so that a separating unit may operate under the strong second normal force, and when at least two pieces of paper P are guided between the feed roller 31 and the separating member 32, the separating member 32 is moved to the first location so that the separating unit may operate under the weak first normal force, thereby simultaneously obtaining effects of preventing miss-feeding, preventing multi-feeding, and preventing abrasion. Seeing such an operation in view of an operating diagram of the separating unit illustrated in FIG. 4c , the first location and the second location are within a region where neither miss-feeding nor multi-feeding occurs. That is, the first location and the second location respectively correspond to regions of window a and window b.
Compared to the first location or the first contact point C1, the second location or the second contact point C2 is at a downstream side with respect to a rotation direction of the feed roller 31. Also, the second location is a location where the second angle G2 between the first line connecting the center 31 a of the feed roller 31 to the center 32 a of the separating member 32 and the second line connecting the contact point of the feed roller 31 and the separating member 32 to the hinge 361 is greater than the first angle G1 at the first location.
Operations of the sheet separation device 1 will now be described. FIGS. 5A to 5E are diagrams of operations of the sheet separation device 1 in a case in which no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32. FIGS. 6A to 6C are diagrams of operations of the sheet separation device 1 in a case in which at least two pieces of paper P are guided between the feed roller 31 and the separating member 32.
First, operations of the sheet separation device 1 in the case in which no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32 will be described with reference to FIGS. 5A to 5E.
Referring to FIG. 5A, the separating member 32 is placed in the first location while in a stop or standby state. Owing to an elastic force of the first elastic member 35 a, the separating member 32 contacts the feed roller 31. Also, the separating member 32 is maintained in the first location by an elastic force of the second elastic member 35 b.
When the feed roller 31 rotates in the direction B1, a torque in the direction B3 acts on the separating member 32 owing to a frictional force between the feed roller 31 and the separating member 32. The separating member 32 does not rotate in the direction B3 due to drag provided by the torque limiter 33. Instead, the hinge 361 is pushed in an opposite direction of the elastic force of the second elastic member 35 b, that is, a direction D1, and the separating member 32 moves to the second location while rotating in the direction B2. While moving from the first location to the second location, the separating member 32 is maintained in contact with the feed roller 31 by the elastic force of the first elastic member 35 a. As illustrated in FIG. 5B, when the separating member 32 reaches the second location, the separating member 32 is driven by the feed roller 31 to rotate in the direction B3.
A second normal force at the second location is greater than a first normal force at the first location. No slip occurs between the feed roller 31 and the separating member 32, and the separating member 32 is driven by the feed roller 31 to rotate. Therefore, abrasion of the feed roller 31 and/or the separating member 32 may be reduced.
As illustrated in FIG. 5C, even when one piece of paper P picked up from the load tray 10 by the pickup roller 20 is guided between the feed roller 31 and the separating member 32, the separating member 32 is maintained in the second location. Since the second normal force is greater than the first normal force, the paper P may be stably transported without miss-feeding.
Though the paper P is completely transported, while the feed roller 31 rotates, as illustrated in FIG. 5D, the separating member 32 is maintained in the second location. When the feed roller 31 stops, as illustrated in FIG. 5E, the hinge 361 is moved in a direction D2. When the feed roller 21 stops rotating, the separating member 32 returns to the first location by the elastic force of the second elastic member 35 b as illustrated in FIG. 5E.
Next, operations of the sheet separation device 1 in the case in which at least two pieces of paper P are guided between the feed roller 31 and the separating member 32 will be described with reference to FIGS. 6A to 6C.
While in the state illustrated in FIG. 5B, paper P is picked up from the load tray 10 by the pickup roller 20 and transported between the feed roller 31 and the separating member 32. In this regard, as illustrated in FIG. 6A, at least two pieces of paper P, for example, the paper P1 and the paper P2, may be guided between the feed roller 31 and the separating member 32. In this regard, since the separating member 32 is placed in the second location and pressed against the feed roller 31 by a strong second normal force, the paper P1 and the paper P2 may be definitely transported without miss-feeding until both pieces of paper P1 and P2 are guided between the feed roller 31 and the separating member 32.
A frictional force between the paper P1 and the paper P2 is less than a frictional force between the paper P1 and the feed roller 31 and a frictional force between the paper P2 and the separating member 32, and accordingly, as illustrated in FIG. 6B, for example, when the two pieces of paper P1 and P2 are definitely guided between the feed roller 31 and the separating member 32, a slip occurs between the paper P1 and the paper P2. Then, since a torque of the feed roller 31 is not transferred to the separating member 32, a load torque applied to the separating member 32 becomes smaller than a threshold torque of the torque limiter 33. Then, the separating member 32 stops. When a torque of the feed roller 31 is not transferred to the separating member 32, a force of maintaining the separating member 32 in the second location is gone, and the hinge 361 is moved in the direction D2 by the elastic force of the second elastic member 35 b. As illustrated in FIG. 6C, the separating member 32 returns to the first location.
In this regard, a quick return operation in which the paper P2 is rapidly returned towards the load tray 10 by the separating member 32 occurs. Also, when the separating member 32 returns to the first location, a slip continuously occurs between the paper P1 and the paper P2, and accordingly, the separating member 32 is maintained in the first location. In an active retard mechanism, the separating member 32 rotates in the direction B2, and in a semi-active retard mechanism, the separating member 32 stops. A first normal force that is weaker than the second normal force acts between the feed roller 31 and the separating member 32. Accordingly, only the paper P1 may be stably separated and transported without multi-feeding.
When the paper P1 is completely transported, and the paper P2 is guided between the feed roller 31 and the separating member 32 again, the paper P2 is transported according to the operations illustrated in FIGS. 5A to 5E.
As described above, when no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32, the separating member 32 moves to the second location, and a strong second normal force acts between the feed roller 31 and the separating member 32. Accordingly, the separating member 32 may be definitely driven by the feed roller 31, and thus, abrasion of the feed roller 31 and/or the separating member 32 may be prevented, and one piece of paper P may be stably transported without miss-feeding.
When at least two pieces of paper P are guided between the feed roller 31 and the separating member 32, the paper P2 contacting the separating member 32 may be momentarily returned in an opposite direction of a transporting direction of the paper P1 as the separating member 32 momentarily returns from the second location to the first location. This is very effective in preventing multi-feeding in a semi-active retard roller mechanism in which the separating member 32 did not reversely rotate, that is, did not rotate in the direction B2. Also, since a first normal force that is weaker than the second normal force acts between the feed roller 31 and the separating member 32 at the first location, only the paper P1 may be stably separated and transported without multi-feeding.
In order to test the effects of the sheet separation device 1 according to the present example, 109 pieces of test paper were prepared. The 109 pieces of test paper includes 10 reams each including 10 pieces of unused paper and 9 pieces of used paper between the reams. Friction coefficients of unused paper and used paper are different from each other, and thus, multi-feeding is likely to occur. For example, the friction coefficient of unused paper is 0.7, and the friction coefficient of used paper is 0.3. The used paper may be, for example, paper having a black or gray image printed on a surface thereof. A result obtained by testing multi-feeding by using such test paper is as follows.
As shown in Table 1 below, in the case of a sheet separation device of the related art in which the separating member 32 is located at a fixed position, a bad result of essentially multi-feeding two pieces of unused paper on used paper was obtained.

	TABLE 1

		Multi-
	Reams of test paper	feeding

	1	2	3	4	5	6	7	8	9	10	rate

Occurrence of	◯	◯	◯	◯	◯	◯	◯	◯	◯	X	9/109
multi-feeding

In the case of the sheet separation device 1 according to the present example, as shown in Table 2 below, a very good result of no multi-feeding was obtained in three tests.

	TABLE 2

		Multi-
	Reams of test paper	feeding

	1	2	3	4	5	6	7	8	9	10	rate

Occurrence of	X	X	X	X	X	X	X	X	X	X	0/109
multi-feeding 1
Occurrence of	X	X	X	X	X	X	X	X	X	X	0/109
multi-feeding 2
Occurrence of	X	X	X	X	X	X	X	X	X	X	0/109
multi-feeding 3

FIG. 7 is a schematic configuration diagram of the sheet separation device 1 according to an example. The sheet separation device 1 illustrated in FIG. 7 is different from the sheet separation device 1 illustrated in FIG. 1 in that the hinge 361 is connected to a link 37 and the link 37 is connected to a rotation shaft 38. According to the above configuration, the hinge 361 moves as the link 37 is rotated in a direction E with respect to the rotation shaft 38. Thus, the separating member 32 may be allowed to move to a first location (denoted by solid lines) and a second location (denoted by dashed lines). Operations of the sheet separation device 1 illustrated in FIG. 7 are the same as described above with reference to FIGS. 5a to 5e and FIGS. 6A to 6C.
FIG. 8 is a perspective view of an implementation example of a structure whereby the separating member 32 may move to first and second locations. The implementation example illustrated in FIG. 8 may be applied to the example of the sheet separation device 1 illustrated in FIG. 7.
Referring to FIG. 8, the holder 36 may have a “U” shape supporting both ends of the separating member 32. Thus, when the separating member 32 moves to the first and second locations, deviation of the separating member 32 in a widthwise direction of paper P may be minimized to allow stable location movement.
In an active retard roller mechanism, a driving member, for example, the driving gear 34 illustrated in FIG. 1a , may be connected to the supporting shaft 321.
The link 37 may have a “U” shape supporting the holder 36 so as to be rotatable on the hinge 361. The link 37 is supported rotatably on the rotation shaft 38. As the link 37 rotates on the rotation shaft 38 in the direction E, the hinge 361 may move, and as the holder 36 rotates on the hinge 361, the separating member 32 may move to the first and second locations.
The first elastic member 35 a is supported by the link 37 and the holder 36. For example, the first elastic member 35 a may be a compressive coil spring having one end portion supported by the link 37 and the other end portion pushing the holder 36. When the separating member 32 moves to the first and second locations, the first elastic member 35 a also moves together, and thus, a change in an elastic force of the first elastic member 35 a at the first and second locations may be minimized. Accordingly, since only a dynamic pressing force changes when the separating member 32 moves to the first and second locations, normal forces at the first and second locations may be stably set so that an operating region of a separating unit may be within the region of the operating diagram of the separating unit illustrated in FIG. 4c , where neither miss-feeding nor multi-feeding occurs.
In the present example, the second elastic member 35 b is connected to the link 37 and applies an elastic force in a direction where the separating member 32 moves to the first location to the link 37. However, the present disclosure is not limited thereto, and as illustrated in FIG. 7, the second elastic member 35 b may be connected to the holder 36.
FIG. 9 is a diagram of the sheet separation device 1 including a guide member 40, according to an example. FIG. 9 illustrates the guide member 40 in detail and the rest of the sheet separation device 1 is omitted. Referring to FIG. 9, the guide member 40 is at an upstream side of the separating member 32 with respect to a transporting direction of paper P. The guide member 40 guides a bottom surface of the paper P so that the paper P picked up by the pickup roller 20 may be stably guided between the separating member 32 and the feed roller 31.
In the present example, the guide member 40 moves along with the separating member 32. That is, even when the separating member 32 moves to first and second locations, relative locations between the separating member 32 and the guide member 40 do not change. Thus, the picked up paper P may be guided by the guide member 40 and stably guided between the feed roller 31 and the separating member 32.
To this end, the guide member 40 is installed at the holder 36. In an example, the guide member 40 may combine with the holder 36. For example, the guide member 40 may be a film-type member, and may be attached to the holder 36. In another example, the guide member 40 may be integrally formed with the holder 36.
FIG. 10 is a perspective view of an implementation example of a structure whereby the separating member 32 may move to first and second locations. The implementation example illustrated in FIG. 10 may be applied to the example of the sheet separation device 1 illustrated in FIG. 1 b.
Referring to FIG. 10, the holder 36 may have a “U” shape supporting both ends of the separating member 32. Thus, when the separating member 32 moves to the first and second locations, deviation of the separating member 32 in a widthwise direction of paper P may be minimized to allow stable location movement.
In an active retard roller mechanism, a driving member, for example, the driving gear 34 illustrated in FIG. 1a , may be connected to the supporting shaft 321.
The hinge 361 may be supported by an elastic frame 60. For example, the hinge 361 may be installed at a bracket 50, and the bracket 50 may be fixed to the elastic frame 60. The bracket 50 may have a “U” shape supporting the holder 36 so as to be rotatable on the hinge 361. The elastic frame 60 may extend in a widthwise direction of the paper P, that is, a length direction of the feed roller 31 and the separating member 32. When no paper P or only one piece of paper P is guided between the feed roller 31 and the separating member 32, a pushing force in a direction from the first location to the second location acts on the separating member 32 as the feed roller 31 rotates. In this regard, while elastically deformed, as denoted by dashed lines in FIG. 10, the elastic frame 60 allows movement of the hinge 361. Accordingly, the separating member 32 may move from the first location to the second location. When at least two pieces of paper P are guided between the separating member 32 and the feed roller 31, or the feed roller 31 stops, the elastic frame 60 elastically returns to the location denoted by solid lines. Thus, the separating member 32 may return from the second location to the first location. As described above, the elastic frame 60 supports the holder 36 so as to be rotatable on the hinge 361, and at the same time, serves as the second elastic member 35 b providing an elastic force in a direction for returning the separating member 32 from the second location to the first location.
Although not illustrated, the hinge 361 may be directly installed at the elastic frame 60.
Although not illustrated, the first elastic member 35 a may be supported by the bracket 50 and the holder 36. Accordingly, since only a dynamic pressing force changes when the separating member 32 moves to the first and second locations, normal forces at the first and second locations may be stably set and controlled.
FIG. 11 is a schematic configuration diagram of the sheet separation device 1 according to an example. In the previous examples, a rotary retard roller is used as the separating member 32. However, in the present example, a retard pad is used as the separating member 32. The retard pad is a friction pad, and satisfies a condition in which a friction coefficient between the retard pad and paper P is less than a friction coefficient between the feed roller 31 and the paper P and is greater than a friction coefficient between pieces of paper P.
The retard pad is, for example, pivotably supported by one end portion of the holder 36. The other end portion of the holder 36 is pivotably supported by the hinge 361. In order to allow movement of the retard pad to a first location (denoted by solid lines) and a second location (denoted by dashed lines), the hinge 361 may be, for example, elastically movable by the structure illustrated in FIG. 1b , FIG. 10, or FIGS. 7 and 8.
Operations in the example in which a retard pad is used as the separating member 32 are the same as described above with reference to FIGS. 5A to 5E and FIGS. 6A to 6C.
The sheet separation device 1 may be used in various apparatuses. FIG. 12 is a block diagram of a sheet processing apparatus including the sheet separation device 1, according to an example. Referring to FIG. 12, the sheet processing apparatus includes a paper feeder 1 a including the sheet separation device 1, and a sheet processor 2 that receives paper P from the paper feeder 1 a and processes the paper P. The processed paper P may be discharged into an output tray 3.
FIG. 13 is a schematic configuration diagram of a scanner 600 including the sheet separation device 1, according to an example. Referring to FIG. 13, the scanner 600 includes a medium processor that reads an image while transporting a document D supplied from a paper feeder including the sheet separation device 1. The medium processor may include a document feeding unit 600 a and a reading unit 600 b that reads an image from a document. The sheet separation device 1 has been described with reference to FIGS. 1 to 11. Since the scanner 600 is an apparatus that reads an image recorded on the document D, the sheet separation device 1 transports the document D.
The reading unit 600 b includes a reading member 650 for reading an image from the document D. The reading member 650 emits light toward the document D, receives light reflected from the document D, and reads an image of the document D. As the reading member 650, a contact-type image sensor (CIS), a charge-coupled device (CCD), or the like may be used.
The scanner 600 uses a flatbed method in which the document D is located at a fixed location and a reading member such as a CIS or a CCD reads an image while moving, a document feeding method in which a reading member is located at a fixed location and the document D is transported, or a combination thereof. The scanner 600 according to the present example is a scanner that uses a combination of the flatbed method and the document feeding method.
The reading unit 600 b includes a platen glass 660 on which the document D is placed to read an image from the document D by using the flatbed method. Also, the reading unit 600 b includes a reading window 670 for reading an image from the document D by using the document feeding method. The reading window 670 may be, for example, a transparent member. In an example, the height of an upper surface of the reading window 670 may be the same as that of an upper surface of the platen glass 660.
When the document feeding method is used, the reading member 650 is located below the reading window 670. When the flatbed method is used, the reading member 650 may be moved in a sub-scanning direction S, that is, in a length direction of the document D, below the platen glass 660 by a transport device as transport means that is not shown. Also, when the flatbed method is used, the platen glass 660 may be externally exposed in order to place the document D on the platen glass 660. For this, the document feeding unit 600 a may rotate with respect to the reading unit 600 b to expose the platen glass 660.
The document feeding unit 600 a transports the document D so that the reading member 650 may read an image recorded on the document D, and discharges the read document D. For this, the document feeding unit 600 a includes a document feeding path 610, and the reading member 650 reads an image from the document D transported along the document feeding path 610. The document feeding path 610 may include, for example, a supply path 611, a reading path 612, and a discharge path 613. The reading member 650 is disposed in the reading path 612, and an image recorded on the document D is read by the reading member 650 while passing through the reading path 612. The supply path 611 is a path for supplying the document D to the reading path 612, and the document D loaded on the load tray 10 is supplied to the reading path 612 via the supply path 611. The discharge path 613 is a path for discharging the document D having passed through the reading path 612. Accordingly, the document D loaded on the load tray 10 is transported along the supply path 611, the reading path 612, and the discharge path 613 and is discharged to a discharge tray 630.
Transport rollers 621 and 622 for transporting the document D withdrawn from the load tray 10 by the sheet separation device 1 may be disposed in the supply path 611. Each of the transport rollers 621 and 622 may have a structure in which a driving roller and a driven roller rotate while being engaged with each other.
Transport rollers 623 and 626 for transporting the document D may be disposed in the reading path 612. For example, the transport rollers 623 and 626 for transporting the document D may be disposed at both sides of the reading member 650. Each of the transport rollers 623 and 626 may have a structure in which a driving roller and a driven roller rotate while being engaged with each other. A reading guide member 624 facing the reading member 650 is disposed in the reading path 612. The reading guide member 624 is pressed against the reading window 670 by its own weight or an elastic member 625, and the document D is transported to come between the reading window 670 and the reading guide member 624. Although not shown, a reading roller that is elastically pressed against the reading window 670 and rotates to transport the document D supplied therebetween may be used instead of the reading guide member 624.
A discharge roller 627 that discharges the document D that has been read is disposed in the discharge path 613. The discharge roller 627 may have a structure in which a driving roller and a driven roller rotate while being engaged with each other.
By the configuration described above, the document D supplied from the sheet separation device 1 is transported along the supply path 611, the reading path 612, and the discharge path 613, and the reading member 650 may read an image from the document D.
FIG. 14 is a schematic configuration diagram of an image forming apparatus 700 including the sheet separation device 1, according to an example. Referring to FIG. 14, the image forming apparatus 700 includes a printing unit (medium processor) 700 a that prints an image on the paper P supplied from a paper feeder. As shown by solid lines in FIG. 14, the paper feeder may be in the form of a cassette feeder 1 b including the sheet separation device 1 and may be under the printing unit 700 a. Also, as shown by dashed lines in FIG. 14, the sheet separation device 1 may be applied to a multi-purpose tray (MPT) 1 c at a side portion of the printing unit 700 a.
The printing unit 700 a according to the present example may print an image on the paper P by using various methods such as an electrophotography method, an inkjet method, a thermal transfer method, or a thermal sublimation method. The image forming apparatus 700 according to the present example prints a color image on the paper P by using an electrophotography method. Referring to FIG. 14, the printing unit 700 a may include a plurality of developing devices 710, an exposure device 720, a transfer device, and a fusing device 740.
For color printing, the plurality of developing devices 710 may include, for example, four developing devices 710 for developing cyan C, magenta M, yellow Y, and black K images. The four developing devices 710 may accommodate cyan C, magenta M, yellow Y, and black K toners, respectively. The printing unit 700 a may further include a developing device 710 for accommodating toners of various colors, such as light magenta and white, in addition to the colors described above, and developing such color images.
The developing device 710 includes a photosensitive drum 7 a. The photosensitive drum 7 a is an example of a photoreceptor having an electrostatic latent image formed on a surface thereof, and may include a conductive metal pipe and a photosensitive layer formed on the outer circumference thereof. A charging roller 7 c is an example of a charger that charges the photosensitive drum 7 a to have a uniform surface potential. A cleaning blade 7 d is an example of a cleaning device as cleaning means that removes toner and a foreign material remaining on a surface of the photosensitive drum 7 a after a transfer process described below.
The developing device 710 supplies toner accommodated therein to an electrostatic latent image formed on the photosensitive drum 7 a and thus develops the electrostatic latent image into a visible toner image. Examples of developing methods include a one-component developing method using toner and a two-component developing method using toner and carrier. The developing device 710 according to the present example uses the one-component developing method. A developing roller 7 b is used to supply toner to the photosensitive drum 7 a. A developing bias voltage for supplying toner to the photosensitive drum 7 a may be applied to the developing roller 7 b.
The one-component developing method may be classified into a contact developing method in which the developing roller 7 b and the photosensitive drum 7 a rotate in contact with each other and a non-contact developing method in which the developing roller 7 b and the photosensitive drum 7 a rotate spaced apart from each other by about tens to hundreds of microns. A supply roller 7 e supplies toner in the developing device 710 to a surface of the developing roller 7 b. A supply bias voltage for supplying toner in the developing device 710 to a surface of the developing roller 7 b may be applied to the supply roller 7 e.
The exposure device 720 forms an electrostatic latent image on the photosensitive drum 7 a by irradiating light modulated according to image information on the photosensitive drum 7 a. As the exposure device 720, a laser scanning unit (LSU) using a laser diode as a light source, a light-emitting diode (LED) exposure device using an LED as a light source, or the like may be used.
The transfer device may include an intermediate transfer belt 731, a first transfer roller 732, and a second transfer roller 733. A toner image developed on photosensitive drums 7 a of the four developing devices 710 is temporarily transferred to the intermediate transfer belt 731. The intermediate transfer belt 731 is circulated while being supported by supporting rollers 734, 735, and 736. Four first transfer rollers 732 are disposed at locations facing the photosensitive drums 7 a of the four developing devices 710 with the intermediate transfer belt 731 therebetween. A first transfer bias voltage for first transferring a toner image developed on the photosensitive drum 7 a to the intermediate transfer belt 731 is applied to the four first transfer rollers 732. The second transfer roller 733 faces the intermediate transfer belt 731. A second transfer bias voltage for transferring the toner image first transferred to the intermediate transfer belt 731 to the paper P is applied to the second transfer roller 733.
Upon receiving a printing command from a host (not shown), a controller (not shown) charges a surface of the photosensitive drum 7 a to a uniform potential via the charging roller 7 c. The exposure device 720 forms an electrostatic latent image on the photosensitive drum 7 a by scanning four light beams modulated according to image information of each color to the photosensitive drums 7 a of the four developing devices 710. The developing roller 7 b develops the electrostatic latent image into a visible toner image by supplying C, M, Y, K toner to corresponding photosensitive drums 7 a, respectively. Developed toner images are firstly transferred to the intermediate transfer belt 731. The paper P is transported from the paper feeder 1 b or 1 c to a transfer nip formed by the second transfer roller 733 and the intermediate transfer belt 731. The toner images firstly transferred on the intermediate transfer belt 731 are secondly transferred to the paper P by the second transfer bias voltage applied to the second transfer roller 733. When the paper P passes through the fusing device 740, the toner images are fused to the paper P by heat and pressure. The paper P on which fusing has been performed is externally discharged by a discharge roller 750.
The scanner 600 and the image forming apparatus 700 may each be used separately, or may be combined with each other and be used as a multifunctional apparatus. FIG. 15 is a schematic diagram of a multifunctional apparatus according to an example.
Referring to FIG. 15, the scanner 600 is disposed on the printing unit 700 a. Structures of the scanner 600 and the printing unit 700 a are the same as shown in FIGS. 13 and 14. The sheet separation device 1 for supplying the paper P to the printing unit 700 a may be realized in various forms. For example, examples of the sheet separation device 1 shown in FIGS. 1 to 11 may be applied to an MPT at a side portion of the printing unit 700 a, as shown in FIG. 14, a main cassette feeder 810 installed under the printing unit 700 a, as shown in FIG. 15, a secondary cassette feeder 820 installed under the main cassette feeder 810, a high capacity feeder 830 installed below the main cassette feeder 810 or under the secondary cassette feeder 820, a high capacity feeder 840 installed at a side portion of the printing unit 700 a, or the like.
It should be understood that examples described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example should typically be considered as available for other similar features or aspects in other examples.
While one or more examples have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.

Claims

1. A sheet separation device comprising:

a feed roller to transport a sheet-type medium in a withdrawing direction of the sheet-type medium;

a separating member movable to first or second contact points on the feed roller to separate a plurality of sheet-type media transported between the feed roller and the separating member; and

an elastic member to apply an elastic force in a direction to allow the separating member to move to contact the feed roller at the first or second contact points,

wherein the separating member is movable to,

the first contact point on the feed roller to apply a first pressing force, and

the second contact point on the feed roller to apply a second pressing force greater than the first pressing force, the second contact point located at a downstream side of the first contact point in the withdrawing direction.

2. The sheet separation device of claim 1, wherein the elastic member includes first and second elastic members,

the first elastic member to apply a first elastic force in a first direction of the separating member to allow the separating member to contact the feed roller at the first or second contact points; and

the second elastic member to apply a second elastic force in a second direction to cause movement of the separating member to the first contact point from the second contact point.

3. The sheet separation device of claim 2, further comprising:

a holder to support the separating member and be rotatable; and

a hinge to rotatably support the holder and to be movable by the first elastic force to enable the separating member to move between the first and the second contact points.

4. The sheet separation device of claim 3, wherein

a second angle formed between a line through the second contact point and a center of the feed roller and a line through the second contact point and the hinge when the separating member is at the second contact point is greater than a first angle formed between a line through the first contact point and the center of the feed roller and a line through the first contact point and the hinge when the separating member is at the first contact point.

5. The sheet separation device of claim 3, further comprising a guide member to

guide a bottom side of the plurality of sheet-type media transported between the feed roller and the separating member, and

move along with the separating member.

6. The sheet separation device of claim 5, wherein the guide member is coupled to the holder.

7. The sheet separation device of claim 3, wherein the first elastic member applies the first elastic force to the holder so that the holder rotates in a direction to allow the separating member to contact the feed roller at the first or second contact points.

8. The sheet separation device of claim 3, further comprising:

a link to which the hinge is coupled; and

a rotation shaft to rotatably support the link.

9. The sheet separation device of claim 8, wherein the second elastic member is to apply the second elastic force to the link.

10. The sheet separation device of claim 3, wherein the second elastic member includes an elastic frame to support the hinge.

11. The sheet separation device of claim 10, wherein the elastic frame extends in a length direction of the feed roller.

12. The sheet separation device of claim 1, further comprising a torque limiter,

wherein the separating member includes a retard roller, and

the torque limiter is to selectively enable, according to a size of a load torque applied to the retard roller, a rotation of the retard roller caused by a rotation of the feed roller.

13. The sheet separation device of claim 12, further comprising a driving member to transfer a torque in a direction opposite to the withdrawing direction.

14. The sheet separation device of claim 1, wherein the separating member includes a retard pad.

15. A sheet separation device, comprising:

a feed roller to transport a sheet-type medium in a withdrawing direction of the sheet-type medium; and

a separating member to separate a plurality of sheet-type media transported between the feed roller and the separating member,

the separating member movable to contact the feed roller at a plurality of contact points on the feed roller along the withdrawing direction to apply different pressing forces corresponding to the plurality of contact points.