JP2002249250A - Feeding device, paper feeding device, image forming device and paper feeding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance paper feeding/separating performance even when high adhesion force is applied between paper sheets, by giving fluctuation to a nip pressure and giving the lowest value condition for the applied time of a low pressure value, in a paper feeding device by an FRR method. SOLUTION: At least 2 pairs of a driving gear and a driven gear or more are provided along the longitudinal direction of the rotation shaft 8 of a reverse roller 2, and either one of gears in each pair has a partially toothless part where no tooth exists. When letting PBLT be the engagement time of a tooth part having least number of teeth, which is a part of the gear having the partially toothless part in the pair of the driving gear and the driven gear disposed nearest to the support point of the rotation shaft 8, at the time when the gear is driven for feeding, letting NIP be the width of a nip part where a feed roller is brought into contact with the reverse roller in the paper carrying direction, and letting VR be the linear velocity of the reverse roller, the relationship equation of PBLT>NIP/VR is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feeding device for feeding sheet-like media such as banknotes, tickets, and sheets one by one, a paper feeding device, a copying machine having the paper feeding device, a printer, a facsimile machine, and the like. The present invention relates to an image forming apparatus and a sheet feeding method.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile, etc., as a sheet feeding apparatus for separating sheets as sheet-like media provided in a stacked state one by one and feeding the separated sheets to an image forming section, From the FRR (feed roller-re
A verse roller type is known. The FRR type paper feeder is provided with a feed roller for transporting paper, a cantilevered rotary shaft having a driven gear, and a free end side of the rotary shaft that is rotatable forward and reverse via a torque limiter. It has a reverse roller that presses against the feed roller and a drive gear that meshes with the driven gear. A change in the frictional force according to the number of sheets entering the nip between the feed roller and the reverse roller causes rotation of the reverse roller in the transport direction and rotation in the return direction with respect to the sheet.

[0003] A schematic configuration and functions of the FRR sheet feeding system will be specifically described with reference to FIG. FRR paper feeding method
As shown in FIG. 14, the frictional force acting between the paper 6 stacked on the tray 7 and the feed roller 1 is set to the highest value, and the frictional force acting between the reverse roller 2 and the paper 6 is set between the papers. By setting a value higher than the frictional force, the conveyance of the uppermost sheet 6 and the separation of the second or lower sheet are performed. In FIG. 14, reference numeral 8 denotes the reverse roller 2
, A cantilevered rotating shaft that supports
Reference numeral 4 denotes a driven gear fixed to the rotating shaft 108, and 3 denotes a driving gear that meshes with the driven gear 4.

In the FRR sheet feeding method, non-feeding can be avoided if the nip pressure is high. However, since double feeding is a method in which the sheet is returned by a reverse roller utilizing the low frictional force between sheets as described above, If the state where the nip pressure is high continues, there is a possibility that the double feed avoidance function may not be realized. From such a viewpoint, Japanese Patent Application Laid-Open No. Hei 5-213468 discloses a configuration in which various types of paper separation are performed by changing the frictional force between the paper and the reverse roller. This is because a piezoelectric element is embedded on the rubber surface of the reverse roller, the paper is vibrated and loosened by the instantaneous high and low vibrations of the nip pressure, and the paper has a width that varies depending on the hardness of the paper. The second and subsequent sheets are prevented from being conveyed, that is, separated, to prevent double feeding.

[0005]

Problems to be Solved by the Invention As shown in FIG.
When the driving gear 3 rotates to rotate the opposing driven gear 4, a driven gear pressure P 1 depending on the radius of the driven gear 4 is generated, and a rotational moment acts in the circumferential direction of the rotating shaft 8. Since the torque limiter 5 is added to the reverse roller 2, a reaction force is generated by the torque limiter return force TA,
This reaction force also contributes to the rotational moment of the rotating shaft 8 in the circumferential direction. As a result, assuming that the radius of the driven gear 4 is RZ and the radius of the reverse roller 2 is RS, the following equation is derived from the balance of the rotational moment of the reverse roller 2 about the rotation shaft 8. RZ · P1 = RS · TA Here, however, here, the friction of rotating the rotating shaft 8 (bearing friction).
Is described as zero.

As shown in FIG. 16, the distance between the fulcrum 9 of the rotating shaft 8 and the driven gear 4 is L1, and the center of gravity of the fulcrum 9 and the rotating shaft 8 (the whole center of gravity including the rotating shaft 8 and the reverse roller 2). The distance between L2 and the distance between the fulcrum 9 and the bearing of the rotary shaft 8 is L2.
3, the distance between the fulcrum 9 and the reverse roller 2 is L4, the own weight of the center of gravity of the rotating shaft 8 and the like is P2, and the pressure of the bearing of the rotating shaft 8 is P
3. Assuming that the nip pressure is PB, the following equation is derived from the balance of the rotational moment about the fulcrum 116. L1 · P1−L2 · P2 = −L3 · P3 + L4 · PB... From the equation, the following equation is derived by eliminating the driven gear pressure P1. PB = (L1 / L4) · (RS / RZ) · TA + (L3 · P3-L2 · P2) / L4... From the formula, the nip pressure PB is obtained in the FRR type sheet feeding device.
Is proportional to the torque limiter return force TA and the distance L1 between the fulcrum 9 and the driven gear.

If the friction coefficient between the feed roller 1 and the sheet 6 is μr, the friction coefficient between the sheets 6 is μp, and the weight per sheet is m, the nip pressure PB in the above equation is , The following equation must be satisfied. PB> TA / μr + (μp / μr) · m Also, in order to prevent double feed, the nip pressure PB in the above equation is used.
Needs to satisfy the following expression. PB <TA / μp−3m Therefore, in order to prevent non-feeding and double feeding, the nip pressure PB in the above formula needs to satisfy the following formula according to the formula. TA / μr + (μp / μr) · m <PB <TA / μp−3m

However, for example, when a high adhesive force is applied between sheets in a high humidity, static electricity environment or the like, if this adhesive force (supposed to act in the shearing force direction) is Q, the following equation is obtained. , The expression becomes ', and as a result, the expression becomes the following expression'. Therefore, the range of the nip pressure PB in the equation becomes significantly narrower. However, here, it is assumed that all the adhesion forces acting between the sheets have the same value, and this is
And PB> TA / μr + (μp / μr) · m + Q / μr ··· PB <TA / μp-3m-2Q / μp ··· TA / μr + (μp / μr) · m + Q / μr <PB <TA / μp-3m-2Q / μp ... '

That is, in the paper feeder of the FRR system, the margin of the nip pressure PB decreases with respect to a high adhesion force,
Depending on the magnitude of the adhesion Q, the nip pressure PB given by the expression satisfying the expression ′ may not exist. Therefore, in the conventional configuration, non-feeding or double feeding may occur.

Accordingly, the present invention provides a feeder and a paper feeder capable of preventing non-feeding and double feeding with high accuracy even in an environment where a high adhesion force acts between sheet-like media such as paper. It is an object of the present invention to provide an image forming apparatus and a sheet feeding method. In other words, according to the present invention, in the method of changing the nip pressure, the weight is set to the high nip pressure that contributes to the prevention of non-feed, and the ideal condition of the application time of the low nip pressure that avoids the double feed is specified. It is an object of the present invention to provide a feeding device, a sheet feeding device, an image forming device, and a sheet feeding method that can be used.

[0011]

According to a first aspect of the present invention, there is provided a feed roller for conveying a sheet-like medium, a cantilevered rotary shaft having a driven gear, and A reverse roller is provided on the free end side of the rotating shaft via a torque limiter so as to be capable of normal and reverse rotation, and has a reverse gear that presses against the feed roller, and a drive gear that meshes with the driven gear. In a feeding device that obtains rotation of the reverse roller in the transport direction and rotation in the return direction of the reverse roller with respect to the sheet-like medium by a change in frictional force according to the number of the entering sheet-like medium, the nip pressure of the nip portion changes. The feeding drive time in the state where the nip pressure is the lowest is set to be longer than the time required for the sheet-shaped medium to pass through the nip portion at a fixed point. , It adopts a configuration that.

According to the second aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilever-type rotating shaft having a driven gear, and a forward / reverse rotating shaft on a free end side of the rotating shaft via a torque limiter. A reverse roller rotatably provided to press against the feed roller, and a drive gear meshing with the driven gear; and In a feeding device that obtains rotation of the reverse roller in the conveyance direction and rotation in the return direction with respect to the sheet-like medium by a change, the nip pressure of the nip portion changes,
In addition, a configuration is adopted in which the feeding drive time in the state where the nip pressure is the lowest is equal to the time when the sheet-like medium passes through the nip portion at a fixed point of the sheet-like medium.

According to the third aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilever-type rotating shaft having a driven gear, and a forward / reverse rotating shaft at a free end side of the rotating shaft via a torque limiter. A reverse roller that is rotatably provided and presses against the feed roller, and a drive gear that meshes with the driven gear. In a feeding device that obtains rotation of the reverse roller in the conveyance direction and rotation in the return direction with respect to the sheet-like medium by a change, the nip pressure of the nip portion changes,
Further, the feeding drive time in the state where the nip pressure is the lowest is set to be larger than a value obtained by dividing the width of the nip portion in the conveying direction of the sheet-like medium by the linear speed of the reverse roller. Has been adopted.

According to a fourth aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilever-type rotating shaft having a driven gear, and a forward / reverse rotation-free end of the rotating shaft via a torque limiter. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device that obtains rotation of the reverse roller in the conveyance direction and rotation in the return direction with respect to the sheet-like medium by a change, the nip pressure of the nip portion changes,
In addition, a configuration is adopted in which the feed driving time in the state where the nip pressure is the lowest is equal to a value obtained by dividing the width of the nip portion in the transport direction of the sheet-like medium by the linear speed of the reverse roller. .

According to a fifth aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a reverse end of the rotary shaft at a free end side via a torque limiter. A reverse roller that is rotatably provided and presses against the feed roller, and a drive gear that meshes with the driven gear. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is the only one set of gear teeth. The feeding drive time in the state where the nip pressure of the nip portion is the lowest is set to be longer than the time for passing the fixed point of the sheet-shaped medium through the nip portion. Yes,
The configuration is adopted.

According to the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotating shaft having a driven gear, and a forward / reverse rotating shaft having a free end side via a torque limiter are provided. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is only one set of gear teeth. A configuration in which the nip pressure of the nip portion is the lowest, and a feeding drive time in a state where the nip pressure of the nip portion is the lowest is equal to a time when the sheet-shaped medium passes through the nip portion at a fixed point. Has been adopted.

According to the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a forward / reverse rotation-free end of the rotary shaft via a torque limiter are provided. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is the only one set of gear teeth. A feed drive time in a state where the nip pressure of the nip portion is the lowest, and the width of the nip portion in the conveying direction of the sheet-like medium is set to a line of the reverse roller. It is configured to be set larger than the value divided by speed.

According to the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a forward / reverse rotating shaft having a free end through a torque limiter are provided. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is the only one set of gear teeth. A feed driving time in a state where the nip pressure of the nip portion is the lowest, and the width of the nip portion in the conveying direction of the sheet-like medium is set to a line of the reverse roller. The value is equal to the value divided by the speed.

According to a ninth aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a forward / reverse rotating shaft on a free end side thereof via a torque limiter. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is the only one set of gear teeth. It has a configuration that is caused by meshing between the segments, and the meshing time at the time of the feeding drive in the tooth portion having the fewest teeth of the gear having the toothless portion in the set of the drive gear and the driven gear closest to the fulcrum of the rotary shaft is set. PB
LT, where NIP is the width of the nip in the transport direction of the sheet-like medium, and VR is the linear velocity of the reverse roller, a relational expression of PBLT> NIP / VR holds.

According to a tenth aspect of the present invention, a feed roller for transporting a sheet-like medium, a cantilevered rotating shaft having a driven gear, and a forward / reverse rotating shaft on a free end side of the rotating shaft via a torque limiter. A reverse roller that is rotatably provided and presses against the feed roller, and a driving gear that meshes with the driven gear, has a frictional force corresponding to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller. In a feeding device for obtaining rotation of the reverse roller in the conveying direction and rotation in the return direction with respect to the sheet-like medium by a change, at least two sets of the driving gear and the driven gear are arranged along the longitudinal direction of the rotating shaft. And any one of the gears in each set has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft at any moment is the only one set of gears. The gear has the configuration caused by the meshing of the parts, and the meshing time at the time of the feeding drive in the tooth portion having the fewest teeth of the gear having the toothless portion in the set of the driving gear and the driven gear closest to the fulcrum of the rotating shaft is set. P
When the width of the nip portion in the transport direction of the BLT and the sheet medium is NIP, and the linear speed of the reverse roller is VR, a relational expression of PBLT = NIP / VR holds.

According to an eleventh aspect of the present invention, in the feeding device according to the ninth or tenth aspect, a distance from the fulcrum to the driven gear when the direction from the fulcrum toward the reverse roller is positive is L, The distance from the fulcrum to the center of gravity of the rotating shaft is L2, the distance from the fulcrum to the bearing on the free end side of the rotating shaft is L3, the distance from the fulcrum to the reverse roller is L4, and its own weight at the center of gravity of the rotating shaft. P2, the pressure at the bearing portion is P3, the return force of the torque limiter is TA, the radius of the driven gear is RZ, the radius of the reverse roller is RS, and the nip pressure of the nip portion is PB. (L2 ・ P2-L3 ・ P3) ・ (RZ / RS) / T
A relational expression of A is established.

According to a twelfth aspect of the present invention, in the feeding device according to any one of the ninth to eleventh aspects, continuous feeding of the set of a driving gear and a driven gear farthest from the reverse roller during feeding driving is performed. The minimum time in one cycle time, which is the sum of the engagement time at one tooth portion and the non-engagement time at the next missing tooth portion, is T, and the conveyance of the sheet-like medium from the pair of the feed roller and the reverse roller. When the distance to the next pair of transport rollers downstream in the direction is DL and the linear velocity of the feed roller is VF, the relational expression of T ≦ DL / VF is established.

According to a thirteenth aspect of the present invention, in the feeding device according to the tenth aspect, the distance from the fulcrum of the rotation shaft in the drive gear and the driven gear closest to the reverse roller is set to LLONG, and the distance between the drive gear and the most distant drive gear is set. When the distance of the driven gear from the fulcrum of the rotary shaft is LSHORT, the optimum transfer performance in a configuration having only one set of drive gears and driven gears is obtained at the distance LFRR1 from the fulcrum of the rotary shaft, and the optimum separation performance. Is obtained at a distance LFRR2 from the fulcrum of the rotation axis, the following relationship is established: LFRR1 = (LLONG + LSHORT) / 2 LFRR2 = LSHORT.

According to a fourteenth aspect of the present invention, in the feeding device according to the tenth aspect, the feed roller line at the time of the feed driving at the tooth portion of the set of the driving gear and the driven gear closest to the fulcrum of the rotary shaft. When the speed is different from the linear speed of the feed roller at the time of the feeding drive at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotary shaft, the former is VF1, and the latter is VF2, VF1 ≧ The configuration that the relational expression of VF2 is established is adopted.

According to a fifteenth aspect of the present invention, in the feeding device according to the tenth aspect, a line of the reverse roller at the time of driving the feed at a tooth portion of a set of a driving gear and a driven gear closest to the fulcrum of the rotary shaft. When the speed is different from the linear speed of the reverse roller at the time of the feeding drive at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotary shaft, the former is VF1 and the latter is VF2, VR1 ≧ A configuration is adopted in which the relational expression of VR2 holds.

According to a sixteenth aspect of the present invention, in the feeding device according to the fourteenth aspect, the line of the reverse roller at the time of the feed driving at the tooth portion of the set of the driving gear and the driven gear closest to the fulcrum of the rotary shaft. When the speed is different from the linear speed of the reverse roller at the time of the feeding drive at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotating shaft, the former is VF1, and the latter is VF2, VR1 ≧ A configuration is adopted in which the relational expression of VR2 holds.

According to a seventeenth aspect of the present invention, in the feeding device according to any one of the ninth to sixteenth aspects, a circumferential end of a tooth portion adjacent to the missing tooth portion in the gear having the missing tooth portion. Is set smaller than the tooth width of the other teeth.

According to an eighteenth aspect of the present invention, in the feeding device according to any one of the first to seventeenth aspects, the feed roller and the reverse roller are formed of rubber, and both rubber hardnesses are K. , K ≧ 37 ° holds.

According to the nineteenth aspect of the present invention, a feed roller for transporting a sheet as a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a free end side of the rotary shaft via a torque limiter. And a driving gear meshed with the driven gear, the frictional force corresponding to the number of sheets entering the nip between the feed roller and the reverse roller. 19. A sheet feeder that obtains rotation of the reverse roller in the conveyance direction and rotation in the return direction with respect to the sheet according to the change of the reverse roller, having the configuration of the feeding device according to any one of claims 1 to 18. The configuration is adopted.

According to the twentieth aspect, the electrostatic latent image formed on the image carrier is developed by a developing means into a toner image, and the toner image is converted into a sheet-like medium fed by a paper feeding device. In the image forming apparatus for transferring to a sheet, the sheet feeding device has a configuration of the feeding device according to one of claims 1 to 18.

According to the twenty-first aspect of the present invention, the nip between the feed roller for transporting the paper and the reverse roller provided on the free end side of the cantilevered rotary shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller with respect to the paper and the rotation in the return direction with respect to the paper are obtained by changing the frictional force according to the number of papers entering the nip portion, and the paper is fed one by one. In the paper feeding method, the nip pressure of the nip portion is changed, and
A procedure is adopted in which the paper feed drive time when the nip pressure is the lowest is set longer than the time required for the paper to pass through the nip at a fixed point.

In the invention according to the twenty-second aspect, the nip between the feed roller for transporting the sheet and the reverse roller provided on the free end side of the cantilevered rotary shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and paper is fed one by one. In the paper feeding method, a nip pressure of the nip portion is changed, and
The paper feed drive time in the state where the nip pressure is the lowest is made equal to the time when the paper passes through the nip portion at a fixed point.

According to the twenty-third aspect of the present invention, the nip between the feed roller for transporting the paper and the reverse roller provided at the free end side of the cantilever type rotary shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and the paper is fed one by one. In the paper feeding method, a nip pressure of the nip portion is changed, and
The paper feeding drive time in the state where the nip pressure is the lowest is set to be larger than the value obtained by dividing the width of the nip in the paper transport direction by the linear speed of the reverse roller.

In the invention according to claim 24, the nip between the feed roller for transporting the paper and the reverse roller provided on the free end side of the cantilever type rotary shaft via the torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and paper is fed one by one. In the paper feeding method, the nip pressure of the nip portion is changed, and
A procedure is adopted in which the paper feed driving time in the state where the nip pressure is the lowest is equal to the value obtained by dividing the width of the nip in the paper transport direction by the linear speed of the reverse roller.

According to the twenty-fifth aspect of the present invention, the nip between the feed roller for conveying the paper and the reverse roller provided on the free end side of the cantilevered rotary shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and paper is fed one by one. In the sheet feeding method, at least two or more sets of a drive gear and a driven gear for rotating the rotation shaft are provided along the longitudinal direction of the rotation shaft, and one of the gears in each set has a circumference. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion in which no teeth exist in the direction, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined as the fixed point of the paper. Larger set than the time to pass through the nip, has adopted a procedure called.

According to the twenty-sixth aspect of the present invention, a nip between a feed roller for conveying a sheet and a reverse roller rotatably and reversely provided via a torque limiter on a free end side of a cantilevered rotating shaft. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and the paper is fed one by one. In the sheet feeding method, at least two or more sets of a drive gear and a driven gear for rotating the rotation shaft are provided along the longitudinal direction of the rotation shaft, and one of the gears in each set has a circumference. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion in which no teeth exist in the direction, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined as the fixed point of the paper. Equal to the time through the nip, it has adopted a procedure called.

According to the twenty-seventh aspect of the present invention, the nip between the feed roller for transporting the paper and the reverse roller provided on the free end side of the cantilever type rotating shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller with respect to the paper and the rotation in the return direction with respect to the paper are obtained by changing the frictional force according to the number of papers entering the nip portion, and the paper is fed one by one. In the paper feeding method, at least two or more sets of a drive gear and a driven gear for rotating the rotation shaft are provided along the longitudinal direction of the rotation shaft, and one of the gears in each set has a circumference. The nip pressure of the nip portion is changed as a configuration having a toothless portion in which no teeth are present in the direction, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined by the method of transporting the paper. The width of the nip portion adopts a procedure that is set larger than the value obtained by dividing the linear speed of the reverse roller at.

According to the twenty-eighth aspect of the present invention, the nip between the feed roller for transporting the paper and the reverse roller that is provided at the free end side of the cantilevered rotary shaft via a torque limiter so as to be capable of normal and reverse rotation. Paper is fed into the nip portion, and the rotation of the reverse roller in the conveyance direction and the rotation in the return direction with respect to the paper are obtained by a change in frictional force according to the number of papers entering the nip portion, and the paper is fed one by one. In the sheet feeding method, at least two or more sets of a drive gear and a driven gear for rotating the rotation shaft are provided along the longitudinal direction of the rotation shaft, and one of the gears in each set has a circumference. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion in which no teeth exist in the direction, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined by a method of transporting the paper. The width of the nip portion adopts a procedure that is equal to the value divided by the linear velocity of the reverse roller at.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, a schematic configuration and functions of a copying machine as an image forming apparatus according to the present embodiment will be described with reference to FIG. The copying machine includes an image reading unit 80 having an ADF (auto document feeder) and an image forming unit 8.
1 and a paper feeding unit 82. In the image reading unit 80,
An image of a document (not shown) is automatically read, the read information is converted into an electric signal, and transmitted to a writing control means (not shown).

The image forming section 81 is provided with a photoreceptor 50 as an image carrier. Around the photoreceptor 50, a charger 52, an optical writing means 51, a developing A unit 53, a transfer / conveying belt 54, a cleaning unit 55, a static elimination lamp (not shown) and the like are arranged. A fixing unit 58 and a sheet discharging unit 59 are provided on the upstream side of the transfer conveyance belt 54 in the conveyance direction. In the case of single-sided copying, the sheet is discharged from the sheet discharging means 59 to a discharge tray (not shown).

The paper supply unit 82 has four paper supply trays 90a, 90 from the top to accommodate different sizes or paper types.
b, 90c, and 90d are provided, and four FRR-type paper feeders 57a, 57
7b, 57c and 57d are provided. Each paper feeder 5
From 7a, 57b, 57c, and 57d, a conveyance path indicated by a broken line extends to the image forming unit 81. The paper fed from these paper feeders 57a, 57b, 57c, 57d is transported toward a pair of registration rollers 85 by a transport guide (not shown). Each paper feeder 57a,
Of the 57b, 57c, and 57d, the lowermost sheet feeding device 57d will be described as an example.
The pickup roller 18 for pulling out the paper stacked on the paper feed tray 90d, the feed roller 1, the reverse roller 2 pressed against the feed roller 1, and the guide 86
And transport rollers 87, 88 and the like. The other paper feeders 57a, 57b, 57c have the same configuration. The copying machine has a manual feed tray 83, and an FRR type paper feeder 57e is provided corresponding to the manual feed tray 83. The paper feeding device 57e has the same configuration as the paper feeding device 57d.

Next, a copying operation by the copying machine will be described. The photoreceptor 50 starts rotating, and during this rotation, the charger 52
As a result, the surface of the photoconductor 50 is uniformly negatively charged. The light writing unit 51 irradiates and scans with a light beam to erase the charge in the light irradiation unit, and forms an electrostatic latent image corresponding to an image to be created. The electrostatic latent image reaches the developing unit 53 with the rotation of the photoconductor 50, where it is visualized as a toner image. The developing system in the present embodiment is a negative-positive developing system, and the developing unit 53 supplies a positive toner to the electrostatic latent image to visualize the electrostatic latent image.

After the toner image is formed, feeding of the sheet is started by the pickup roller 18 at a predetermined sheet feeding timing, and the sheet reaches the registration roller pair 85 via a conveyance path shown by a broken line. At this point, the photoconductor 5 is temporarily stopped and corrected for oblique displacement, etc.
The photoconductor 50 and the transfer / transport belt 54 are moved at a timing when the leading edge of the toner image on
Is sent to the transfer section. At the transfer portion, the toner image is transferred to the sheet by the transfer bias applied. The sheet on which the toner image has been transferred is fused and fixed by the fixing unit 58 with heat and pressure by the heat and pressure, and is conveyed to the sheet discharging unit 59. Residual toner remaining on the photoreceptor 50 without being transferred by the transfer unit is
The rotation of the photoconductor 50 reaches the cleaning unit 55, and the cleaning unit 55 cleans and removes the cleaning unit 55.
Further, the residual potential on the photoreceptor 50 is initialized by an unillustrated static elimination lamp to prepare for the next image formation.

Next, the configuration and functions of the FRR type sheet feeding device 57d will be described in detail with reference to FIGS.
As shown in FIG. 1, a bundle S of sheets as a sheet-like medium is aligned by a support member (not shown), and is stacked even if the number of sheets is reduced by feeding or the number of sheets is added by replenishment. The height of the uppermost surface of the paper is maintained at a constant position. Reference numeral X indicates a sheet feeding (feeding) direction, and a pickup roller 18 is provided on the upper surface of the sheet at the center in the width direction of the sheet orthogonal to the sheet feeding direction X and on the downstream side in the sheet feeding direction X. It is in contact with its own weight.

Pickup roller 1 in paper feeding direction X
In the vicinity of the downstream side of the feed roller 8, the feed roller 1 and the reverse roller 2 are arranged to face each other in a pressure-contact state. The position of the nip between the feed roller 1 and the reverse roller 2
Is set to the same height level as the topmost sheet.
The feed roller 1 is provided on a feed roller drive shaft (not shown) supported in a cantilevered state on the main body frame 9 (see FIG. 2), and is synchronized with a gear 1G integrally provided on the feed roller drive shaft. Rotate. The gear 1G meshes with a gear 18G provided integrally with the rotation shaft 18a of the pickup roller 18 via an idle gear 20G. Therefore, the pickup roller 18 and the feed roller 1 are rotated in the sheet feeding direction X to feed the sheet.

As shown in FIG. 2, the reverse roller 2 can be rotated forward and reverse through a torque limiter 5 on a free end side of a rotating shaft 8 supported in a cantilever manner with the main body frame 9 as a fulcrum. It is provided in. The rotating shaft 8 penetrates a vertically extending elongated hole 14a formed in the auxiliary side plate 14 which is a part of the main body frame 9, and a flanged bearing 16 is provided in the penetrating portion so as to be vertically displaceable. ing.
As shown in FIG. 1, the auxiliary side plate 14
The arm 24a of the lever 24 rotatably supported by the support shaft 22 is in contact with the lever 24 by elastic force. This elastic force is given by a moment due to the elasticity of the spring 26 locked to the one end 12 b of the lever 24. Spring 2
6, the reverse roller 2 is pressed against the feed roller 1.

As shown in FIG. 2, the rotating shaft 8 has a fulcrum-side driven gear 10 at a position (hereinafter referred to as a fulcrum-fulcrum-side driven gear) La from the main frame 9 as a fulcrum.
The reverse roller-side driven gear 11 is provided at a position Lb from the fulcrum (hereinafter referred to as a distance between the fulcrum and the reverse roller-side driven gear). A drive shaft 15 is supported between the main body frame 9 and the auxiliary side plate 14 substantially in parallel with the rotating shaft 8, and the fulcrum-side driven gear 1
0, and a reverse roller side drive gear 13 facing the reverse roller side driven gear 11
Is provided. The drive shaft 15 is provided with a rotational driving force by a motor 17 fixed to the main body frame 9.

The fulcrum-side driven gear 10 and the reverse roller-side driven gear 11 have a configuration in which the entire circumference is a tooth portion. On the other hand, the fulcrum-side drive gear 12 and the reverse roller-side drive gear 13 have no teeth in a certain partial area, that is,
It has a missing tooth portion with one or more teeth. The fulcrum-side drive gear 12 and the reverse roller-side drive gear 13 are
At the time of paper feed driving, the rotational drive force is transmitted to the opposing fulcrum-side driven gear 10 and the reverse roller-side driven gear 11 only at the tooth portions. The fulcrum-side driven gear 1
0 and the reverse roller side driven gear 11 may have a missing tooth portion. In this case, the fulcrum-side drive gear 12
The entire periphery of the reverse roller side drive gear 13 is a tooth portion.

The phase relationship regarding the angle between the toothless portion and the tooth portion of the fulcrum-side drive gear 12 and the reverse roller-side drive gear 13 is alternately configured. This will be described in detail with reference to FIG. As shown in FIG. 3A, the fulcrum-side drive gear 12 has four teeth in a counterclockwise direction by cutting some of the teeth and missing teeth in a configuration of 32 teeth per circumference. Tooth part 12a, toothless part 12b without three teeth, tooth part 12c with three teeth, toothless part 12d without three teeth, tooth part 12e with three teeth, toothless part 12f without three teeth, three teeth Has a toothed portion 12g, a toothless portion 12h without three teeth, a toothed portion 12i with three teeth, and a toothless portion 12j without four teeth. Of course, it may be formed by integral molding (the same applies hereinafter). On the other hand, the reverse roller side drive gear 13 is
As shown in FIG. 3B, in the counterclockwise direction, in order, the toothless portion 13a without four teeth, the tooth portion 13c with three teeth, the toothless portion 13c without three teeth, and the tooth portion 13d with three teeth Missing tooth portion 13e without three teeth 13f Missing tooth portion 13f without three teeth 13g Missing tooth portion 13g without three teeth 13h Missing tooth portion 13i without three teeth Four-tooth missing tooth portion 13j.

Tooth portion 1 with four teeth of fulcrum side drive gear 12
The quadrant 2a corresponds to the toothless portion 13a without the four teeth of the reverse roller side drive gear 13, and conversely, for example, the quadrant of the toothless portion 12j without the four teeth of the fulcrum side drive gear 12,
Four-toothed tooth portion 13 of reverse roller side drive gear 13
j corresponds. With such a configuration, when the reverse roller-side drive gear 13 and the fulcrum-side drive gear 12 are driven to rotate simultaneously at the time of paper feed driving, the reverse roller-side driven gear 11 and the fulcrum-side driven gear 10 are alternately meshed with each other and differ from the fulcrum. The rotational driving force is transmitted to the rotating shaft 8 with the distances La and Lb.

Therefore, in the above equation for determining the nip pressure PB, when the reverse roller-side driven gear 11 and the reverse roller-side driving gear 13 mesh with each other, the distance L1 is equal to the fulcrum.
It becomes the distance Lb between the reverse roller-side driven gears, and the nip pressure PB is expressed by the following equation. PB = (Lb / L4) · (RS / RZ) · TA + (L3 · P3−L2 · P2) / L4.. The distance L1 between the driven gears is the distance La between the fulcrum and the fulcrum-side driven gear, and the nip pressure PB is given by the following equation. PB = (La / L4) · (RS / RZ) · TA + (L3 · P3-L2 · P2) / L4

Therefore, at the time of paper feeding, the nip pressure PB expressed by the equation and the equation is continuously repeated, and La <
Since Lb, the nip pressure PB is smaller in the equation than in the equation, and as a result, the nip pressure PB shows a pressure value that fluctuates between high and low. This pressure fluctuation is shown in FIGS.
A description will be given based on the timing chart of FIG. As shown in FIG. 3, both the fulcrum-side drive gear 12 and the reverse roller-side drive gear 13 rotate counterclockwise. When the tooth portion 13j having four teeth of the reverse roller side drive gear 13 meshes with the opposing reverse roller side driven gear 11, the fulcrum side drive gear 12 is moved to the opposite fulcrum side driven gear 10
Does not mesh with That is, as shown in FIG. 4, the engagement timing T13 of the reverse roller
Turns ON, and at the same time, the engagement timing T12 of the fulcrum-side drive gear 12 turns OFF.

At this time, the nip pressure PB has a maximum value as shown by the timing TV of the pressure fluctuation (the maximum value and the minimum value of the nip pressure PB) because the distance between the reverse roller side drive gear 13 and the fulcrum is long. Indicates PBmax. The maximum value PBmax of the nip pressure PB occurs while the tooth portion 13j is in contact with the reverse roller-side driven gear 11, that is, during the rotation time 13jt. After the rotation time 13 jt has elapsed, the tooth portion 12 a having four teeth of the fulcrum-side drive gear 12 meshes with the fulcrum-side driven gear 10, and the reverse roller-side drive gear 13 and the reverse roller-side driven gear 11 do not mesh with each other. In this case, the fulcrum-side drive gear 1
2 is turned ON, and at the same time, the meshing timing T1 of the reverse roller side drive gear 13 is set.
3 turns OFF. At this time, the nip pressure PB shows the minimum value PBmin as shown at the pressure change timing TV because the fulcrum-side drive gear 12 is short from the fulcrum. The minimum value PBmin of the nip pressure PB occurs while the tooth portion 12a is in contact with the fulcrum-side driven gear 10, that is, during the rotation time 12at.

After the rotation time 12at has elapsed, the tooth portion 13 having three teeth in the reverse roller side drive gear 13
b meshes with the reverse roller-side driven gear 11, and
The fulcrum-side drive gear 12 and the fulcrum-side driven gear 10 do not mesh with each other. In this case, the engagement timing T13 of the reverse roller side drive gear 13 turns ON, and at the same time, the engagement timing T12 of the fulcrum side drive gear 12 turns OFF.
At this time, the nip pressure PB is determined by the pressure change timing TV.
Shows the highest value PBmax. The maximum value PBmax of the nip pressure PB occurs while the tooth portion 13b is in contact with the reverse roller-side driven gear 11, that is, during the rotation time 13bt.

After the lapse of the rotation time 13 bt, the tooth portion 12 c having three teeth of the fulcrum-side drive gear 12 meshes with the fulcrum-side driven gear 10, and the reverse-roller-side drive gear 13 and the reverse-roller-side driven gear 11 Does not mesh. In this case, the engagement timing T12 of the fulcrum-side drive gear 12 turns ON, and at the same time, the engagement timing T13 of the reverse roller-side drive gear 13 turns OFF.
At this time, the nip pressure PB is determined by the pressure change timing TV.
Shows the minimum value PBmin. The minimum value PBmin of the nip pressure PB is determined while the tooth portion 12c is in contact with the fulcrum-side driven gear 10, that is, the rotation time 12c.
occurs between t. Thereafter, similarly, the nip pressure PB becomes the maximum value PBm during a time corresponding to the rotation range of the tooth portion of the fulcrum-side drive gear 12 and the reverse roller-side drive gear 13.
ax and the minimum value PBmin are repeated.

In the fulcrum-side drive gear 12 and the reverse roller-side drive gear 13 in this embodiment, the tooth width at the circumferential end of the tooth portion adjacent to the missing tooth portion is set smaller than the tooth width of the other teeth. It has a configuration that Fulcrum drive gear 1
Taking as an example a tooth portion 12a having two 4 teeth, as shown in FIG. 5, 12a-
1 and 12a-4 are inner teeth 12a-2 and 12a
The tooth width is formed narrower than -3 (claim 17).
With this configuration, at the moment when the meshing starts via the toothless portion or when the transition from the meshing state to the toothless portion occurs, the meshing ratio with the fulcrum-side driven gear 10 and the reverse roller-side driven gear 11 is improved, and noise is reduced. I do.

In the present embodiment, in the configuration for obtaining the pressure fluctuation of the nip pressure PB, a configuration for further providing a minimum value condition of the application time of the low pressure value is provided. This is shown in FIG.
It will be described based on. The tooth portion of the fulcrum drive gear 12 is
When meshing with the fulcrum-side driven gear 10 at the time of paper feed drive, the minimum value of the meshing time with the fulcrum-side driven gear 10 at the time of paper feed drive, in other words, of the tooth portion In the tooth part of the area where the width in the circumferential direction is the smallest, or the part where the number of continuous teeth is the least in the tooth part,
Assuming that the minimum meshing time is PBLT and the time of meshing with the fulcrum-side driven gear 10 is VR, the reverse roller linear speed is VR, and the nip width formed by the contact between the feed roller 1 and the reverse roller 2 is NIP, the following equation is obtained. It is configured to be established (claims 3, 7, 9, 23, 27). PBLT> NIP / VR ...

More specifically, the minimum meshing time PBLT is determined by setting the rotation speed of the fulcrum-side drive gear 12 to ω, the number of teeth forming the tooth portion in the narrowest region among the tooth portions to NMIN, and the entire circumference to indicate the tooth portion. If the total number of teeth is assumed to be NALL, it is determined by the following equation (10). However, the coefficient 60 is the fulcrum-side drive gear 1
2 is to convert the unit of the rotation speed ω from [rpm] to [rps]. In this case, the unit of the PBLT is [second]. PBLT = (60 / ω) × (NMIN / NALL) (10) Therefore, for example, the nip width NIP is actually measured, the PBLT is obtained from the reverse roller linear velocity VR known from the design specification, and the equation 10 is satisfied so as to satisfy the equation. NALL and NMI by
N may be determined. The time at which an arbitrary fixed point on the paper actually passes through the NIP may be obtained by an experiment or the like (including computer simulation), and this may be set as the PBLT (claims 1, 5, 5, 21 and 25).

FIG. 7 shows an experimental result of measuring the maximum transport force and the maximum separation force of the paper when the adhesion force Q acts between the papers in the above-mentioned FRR type paper supply configuration. 5 trials
And the average is plotted. However, the maximum conveying force was obtained by attaching a force sensor to one sheet of paper and fixing the force sensor as the maximum fixing force at the start of the paper feeding operation. On the other hand, the maximum separation force was obtained by measuring the maximum value of the adhesion force that can be separated in a state where a pseudo adhesion force is imposed by adding a droplet between two sheets of paper. The maximum conveying force and the maximum separating force are shown converted into the nip pressure PB based on the equations (1) and (2). In addition, the experiment shows that the minimum engagement time PBLT
Was used as a parameter. Therefore, the horizontal axis in FIG. 7 gives the minimum engagement time PBLT. However, it is expressed as a dimensionless amount by dividing by (nip width NIP / reverse roller linear velocity VR).

The vertical axis in FIG. 7 shows the nip pressure PB normalized and its ratio value. In this case, the value 0 on the vertical axis indicates the nip pressure PB (minimum value) in the equation, and the value 1 on the vertical axis indicates the nip pressure PB (highest value) in the equation. As is clear from FIG. 7, the minimum engagement time PB
As LT increases from 0.7 [sec / (NIP / VR)], the nip pressure PB on the left-hand side of the equation を that determines double feed avoidance with cohesion decreases rapidly, and the minimum meshing time P
When BLT ≧ 1 [second / (NIP / VR)], the nip pressure PB (minimum value) in the equation is saturated, and the margin for the adhesion Q on the right side of the equation ′ is most improved. Also, at this time, the nip pressure PB, which is the left-hand side value of the equation ′ that determines the non-feeding accompanied by the contact force, monotonously decreases from the nip pressure PB (highest value) in the equation with the increase of the minimum engagement time PBLT. Nip pressure PB in the equation
(Lowest value) and maintain the height.

Therefore, in the paper feeder according to the present embodiment that satisfies the expression, unlike the conventional FRR type paper feeder,
The nip pressure PB of the left-hand side of the equation for determining the avoidance of double feed with cohesion is kept at a minimum value, and the nip pressure PB, the left-hand side value of the equation for determining the avoidance of non-feeding, is kept higher than the minimum value. Can be. Therefore, it is possible to avoid the non-feeding accompanied by the contact force, and it is possible to increase the contact force Q in the formula (1) which determines the avoidance of the double feed accompanied by the contact force. Performance can be improved.

[Embodiment 1] An embodiment of the FRR system will be described with reference to FIGS. 8 to 10 and Table 1. In this embodiment, two driven gears (corresponding to the fulcrum-side driven gear 10 and the reverse roller-side driven gear 11) having 21 teeth per circumference are shared, and three types of two driving gears (the fulcrum-side driving gear 12, the reverse Roller side drive gear 1
(Equivalent to 3) will be described with reference to the experimental results of the maximum separation force.

As shown in FIG. 8 (a), the three types of drive gears include a fulcrum drive gear 120 having no missing teeth.
And a reverse roller side drive gear 13 having no missing tooth portion
The drive gear 30 was formed by cutting some teeth in a different pattern for each type. FIG. 8B shows a side surface of the drive gear 30. The three types of drive gears manufactured by cutting are distinguished as type a, type b, and type c, respectively, as shown in FIG. Type a has a fulcrum-side drive gear 120a and a reverse roller-side drive gear 130a, as shown in FIGS. 9A and 9B.
As shown in FIG. 9D, a fulcrum-side drive gear 120b and a reverse roller-side drive gear 130b are provided, and the type c is, as shown in FIGS.
c and a reverse roller side drive gear 130c. The above three types of drive gears have different patterns of tooth portions and missing tooth portions, and these patterns are shown in the second and third columns of Table 1.

[0064]

[Table 1]

The fulcrum-side drive gear 120a has two teeth, ten teeth, two teeth, and ten teeth in one round. Corresponding to this, the reverse roller side drive gear 130a has a configuration with 10 teeth, 2 teeth, 10 teeth, and 2 teeth. The fulcrum-side drive gear 120b has three teeth, no nine teeth, three teeth, and nine teeth in one round. Correspondingly, the reverse roller-side drive gear 130b has a configuration with nine teeth, no three teeth, nine teeth, and no three teeth. The fulcrum-side drive gear 120c has four teeth, no eight teeth, four teeth, and no eight teeth in one round. Correspondingly, the reverse roller side drive gear 13
0c has eight teeth, four teeth, eight teeth, and four teeth. As described above, the three types of drive gears have a configuration in which the tooth portion and the missing tooth portion differ by one as the alphabet for distinguishing the types changes in the order of a, b, and c. Below, each experiment of the maximum separation power was performed.

In the experiment of the maximum separating force, the rotation speed was 398 rpm and the reverse roller diameter was 27 mm for all three types of drive gears. As a result, the reverse roller linear velocity VR
Became 643 mm / sec. At this time, for the three types of drive gears, the number of teeth in the tooth portion and the missing tooth portion for each type and the minimum meshing time PBLT calculated based on the rotation speed are shown in the fourth column of Table 1. However, when the nip pressure PB is separately transiently measured by a pressure sensor, the minimum engagement time PBLT is determined by the addition of the attenuation of the rubber constituting the feed roller and the reverse roller and the loss at the time of engagement of the drive gear and the driven gear. Due to the effect of the responsiveness of the deflection of both the feed roller and the reverse roller shaft, the response is relaxed when the nip pressure PB transitions from the maximum value to the minimum value or from the minimum value to the maximum value. The measured value was lower than the calculated value shown in FIG. Therefore, only in the case of the experiment conducted here, it should be recognized that the minimum meshing time PBLT becomes the value shown in the fifth column due to the experimental environment and configuration, and the restrictions of the rubber material used. The maximum separation force experiment was performed by regarding the value shown in the fifth column as the minimum engagement time PBLT.

In the sixth column of Table 1, the result of measuring the maximum separating force is shown as a ratio value obtained by converting the value into the nip pressure PB using the formula 下 below. As for this ratio value, the value 0.00 indicates the minimum value of the nip pressure PB, and the value 1.00
Indicates the maximum value of the nip pressure PB. On the other hand, the nip width NIP is approximately 4.0 mm on average as a result of the measurement, whereby the value NI obtained by dividing the nip width NIP = 4.0 mm by the reverse roller linear velocity VR = 643 mm / sec.
P / VR was 4/643 = 6.2 msec. Therefore, the minimum meshing time PBLT for the three types of drive gears shown in the fifth column of Table 1 is calculated by using the obtained NIP / VR
= 6.2 msec, the drive gears of type b and type c satisfy the condition of PBLT> NIP / VR, and at this time, the ratio values shown in the sixth column of Table 1 have the values −0. The value of 10, 0.00 was around 0.00. On the other hand, in the case of a type a drive gear, PBLT
<NIP / VR, PBLT> The condition of NIP / VR was not satisfied, and the ratio value was 0.50, which was a value between the values 0.00 and 1.00.

In the seventh column of Table 1, the minimum engagement time PBLT in the fifth column is calculated as NIP / VR = 6.2 ms.
The value divided by c is shown. FIG. 10 is a graph of the values in the sixth column with respect to the values shown in the seventh column. From FIG. 10, PBLT [sec / (NIP / V
R)] determines whether or not the nip pressure PB of the left-hand side of the equation ′ that determines the avoidance of double feed accompanied by adhesion is saturated with the nip pressure PB (minimum value) in the equation, with the value approximately 1 as a boundary. You can see that. Further, if the value of PBLT is 1 or more, it can be confirmed that the nip pressure PB on the left side of the expression 決 め る that determines the avoidance of double feed accompanied by the adhesion force matches the nip pressure PB (minimum value) in the expression.

As a result, it has been confirmed that when the value of the PBLT is 1 or more, the margin is most improved with respect to the adhesion force Q on the right side of the equation (1). In the above experiment,
If the experimental environment and configuration, and the rubber material used were configured to have an agile response to the nip pressure PB, the calculated values shown in the fourth column of Table 1 indicate the true minimum meshing. Adopted as time PBLT. At this time, NIP
/VR=6.2 msec, so that in the three types of drive gears from type a to type c, PBLT> N
After satisfying the condition of IP / VR and converting the result of measuring the maximum separation force into the nip pressure PB based on the equation (1), the ratio values obtained by normalizing this value are all 0.00 or 0. The nip pressure PB on the left-hand side of the expression ′ that determines the avoidance of double feed accompanied by the adhesion is equal to the nip pressure PB (minimum value) in the expression, and has a margin for the adhesion Q on the right-hand side of the expression ′. The degree is the most improved. As an example in which the nip pressure PB is configured to have a quick response, for example, in the experimental environment and the configuration, the backlash may be eliminated and the hardness of both the feed roller and the reverse roller may be increased. The rubber material constituting the feed roller and the reverse roller can be achieved by using a vibration-proof rubber material.

Next, another embodiment (corresponding to claim 11)
Will be described. Since the configuration and functions are the same as those of the above embodiment, illustration and description will be omitted unless otherwise required,
Only the main part will be described (the same applies to other embodiments described below). In the paper feeder according to the present embodiment, the nip pressure PB, which is the left-hand value of the equation, is set to a value greater than zero, so that the following equation 11 is established. L1> (L2 · P2−L3 · P3) · (RZ / RS) / TA (11) The distance L1 between the fulcrum and the fulcrum-side driven gear is calculated from the fulcrum when the direction from the fulcrum toward the reverse roller 2 is positive. Refers to the distance to the driven gear. Accordingly, the driven gear may be disposed at a position from the fulcrum in the direction opposite to the reverse roller 2, and in this case, the distance L1 between the fulcrum and the fulcrum-side driven gear becomes a negative value. According to Equation 11, the fulcrum-side driven gear 1
The equation which is the nip pressure PB accompanying 0 is always positive, and the contact between the reverse roller 2 for avoiding the double feed accompanied by the contact force and the sheet to be separated is always assured.
The reverse roller 2 rotating at R reliably transmits the return force by rotation to the paper to be separated. Therefore, it is possible to reliably improve the paper feed separation performance in the case where the adhesion force acts between the sheets.

Next, another embodiment (corresponding to claim 12) will be described with reference to FIGS. In the paper feeding device according to the present embodiment, as shown in FIG. I have. In such a configuration, the meshing time of one continuous tooth portion at the time of paper feed driving in the set of the fulcrum-side driving gear 12 and the fulcrum-side driven gear 10 farthest from the reverse roller 2 and the non-meshing due to the next one missing tooth portion When the minimum time is T and the linear velocity of the feed roller 1 is VF in one cycle time consisting of the total time, the following equation 12 is satisfied. T ≦ DL / VF ・ ・ ・ 12

As shown in FIG. 13, the fulcrum-side drive gear 12
, One tooth portion 12a and one missing tooth portion 12
j is adjacent. The time required for the rotation of the fulcrum-side drive gear 12 to rotate the quadrant of the tooth portion 12a and the missing tooth portion 12j and that is shorter than that of any other combination of the tooth portion and the missing tooth portion. As one cycle time T1
It is shown. The right side of Expression 12 indicates the time during which the paper to be fed is transported by the distance DL, which is the distance DL
Is divided by the feed roller linear velocity VF. When the one cycle time T1 is set to be less than the right side value of Expression 12, at least once until the sheet to be fed is conveyed by the distance DL,
When the nip pressure PB shown by the formula is applied, and the adhesion force acts between the sheets, the sheet separation performance can be reliably improved.

Next, another embodiment (claims 4, 8, 1)
0, 24, and 28). The sheet feeding device according to the present embodiment is configured so that the following Expression 13 is satisfied. PBLT = NIP / VR ... 13 As described with reference to FIG. 7, the minimum meshing time PBLT = 1
In [second (NIP / VR)], the nip pressure PB of the left side of the equation 決 め る that determines the double feed avoidance with the adhesion force is saturated with the nip pressure PB (minimum value) in the equation and becomes minimum, so that the right side The margin with respect to the adhesion Q is most improved.
At the same time, the nip pressure PB on the left-hand side of the expression 決 め る that determines non-feeding with cohesion is substantially the intermediate value between the nip pressure PB (highest value) in the expression and the nip pressure PB (lowest value) in the expression, and PBLT ≧ 1. This is the maximum in the range of [seconds (NIP / VR)], and the non-sending avoidance performance with adhesion (in other words, the transport performance) is the maximum. Therefore, in the sheet feeding device according to the present embodiment, the sheet feeding / separation performance when the adhesion force acts between the sheets is improved, and the margin for avoiding non-feeding is maximized. The PBLT may be grasped as a time when a fixed point on the paper passes through the nip portion.
6, 22, 26).

Next, another embodiment (corresponding to claim 13)
Will be described. In the present embodiment, it is an object of the present invention to embody an approach for obtaining the non-feeding avoidance performance accompanied by the contact force and the separation performance accompanied by the contact force to facilitate the design. Specifically, the distance from the fulcrum of the rotating shaft 8 in the reverse roller side drive gear 13 and the reverse roller side driven gear 11 closest to the reverse roller 2 is LLON.
G, the distance from the fulcrum of the rotary shaft 8 in the fulcrum-side drive gear 12 and the fulcrum-side driven gear 10 to the farthest point,
In the configuration having only one set of the driving gear and the driven gear, the optimum conveyance performance is obtained at the distance LFRR1 from the fulcrum of the rotating shaft 8 and the optimum separation performance is obtained at the distance LFRR2 from the fulcrum of the rotating shaft 8. In this case, the following expressions 14 and 15 are satisfied. LFRR1 = (LLONG + LSHORT) / 2... 14 LFRR2 = LSHORT.

When the minimum engagement time PBLT = 1 [second (NIP / VR)], the sheet feeding device having the maximum non-feeding allowance margin has a nip pressure PB on the left-hand side of the expression 決 め る that determines the avoidance of double feeding accompanied by adhesion. Is the nip pressure PB (minimum value) in the formula
And the minimum, the margin with respect to the adhesion Q on the right side is most improved. At the same time, the nip pressure PB on the left-hand side of the expression ′ that determines non-feeding with cohesion is approximately the middle value between the nip pressure PB (highest value) in the expression and the nip pressure PB (lowest value) in the expression, and PBLT ≧ 1
The maximum is within the range of [seconds (NIP / VR)], and the non-sending avoidance performance accompanied with the adhesion (in other words, the transport performance) is maximum.

Accordingly, in this case, the expressions 14 and 15 are the same as those of the FRR type paper feeder having a single driving gear and a driven gear having a nip pressure PB as shown in the following expression 16. The separation performance is the same as that of an FRR type paper feeder having a single drive gear and a driven gear having a nip pressure PB shown in the equation. PB = ((La + Lb) / 2 / L4) · (RS / RZ) / TA + (L3 · P3−L2 · P2) / L4 Therefore, the paper feeder having the maximum non-sending avoidance margin is designed. In this case, the actual performance of the FRR paper feeder is such that the distance between the fulcrum and the fulcrum-side driven gear is (La + Lb) / 2 for the transport performance, and the FRR type paper feeder is that the distance between the fulcrum and the fulcrum-side driven gear is La for the separation performance. It is performed while recognizing and confirming the paper feeder.

Next, another embodiment (corresponding to claim 14)
Will be described. The paper feeder according to the present embodiment has a configuration in which the non-feeding avoidance margin is maximized, and the feed roller linear speed at the time of paper feed driving at the tooth portion by the fulcrum-side drive gear 12 and the fulcrum-side driven gear 10 is controlled by the reverse roller-side drive. Unlike the feed roller linear speed at the time of paper feed driving at the tooth portion by the gear 13 and the reverse roller side driven gear 11, the former is VF
1. When the latter is VF2, the following equation 17 is satisfied: VF1 ≧ VF2 17

In the equation (17), when VF1 = VF2 × 1.2, the sheet is fed because the feed roller linear speed of the sheet to be fed is increased within the application time of the nip pressure PB (minimum value) in the equation. The slip performance of the paper to be fed and the feed roller 1 was improved. That is, since the transport performance was improved, the experimental result shown in FIG. 7 shows that the nip pressure PB, which is the left-hand side value of the equation for determining non-feed avoidance, was uniformly increased by + 4% regardless of the minimum meshing time PBLT (experimental experiment) Average of the number of times 3). From this, the minimum engagement time PBLT
= 1 [sec (NIP / VR)], the nip pressure PB of the left-hand side of the equation 決 め る that determines the double feed avoidance with cohesion is saturated with the nip pressure PB (minimum value) in the equation and becomes minimum. The margin for the adhesion Q on the right side is improved.
At the same time, the nip pressure PB on the left-hand side of the expression 決 め る which determines non-feeding with cohesion is + 4% above the intermediate value between the nip pressure PB (highest value) in the expression and the nip pressure PB (lowest value) in the expression. At the same time, the maximum value is in the range of PBLT ≧ 1 [second (NIP / VR)], and the non-sending avoidance performance accompanying the adhesion force is higher than the case of only the configuration with the maximum non-sending avoidance margin. Therefore, it is possible to obtain the sheet feeding performance in the case where the adhesion force acts between the sheets, and also to obtain the sheet feeding performance with a large non-feeding allowance margin.

Next, another embodiment (corresponding to claim 15)
Will be described. In the paper feeder according to the present embodiment, in addition to the configuration in which the non-feeding avoidance margin is the maximum, the linear speed of the reverse roller during the paper feed driving at the tooth portion by the fulcrum-side drive gear 12 and the fulcrum-side driven gear 10 is reduced. Unlike the reverse roller linear speed at the time of paper feed driving at the tooth portion by the gear 13 and the reverse roller side driven gear 11, the former is VR
1. When the latter is VR2, the following equation 18 is satisfied. VR1≥VR2 ... 18

In equation (18), VR1 = VR2 × 1.15
In this case, since NIP / VR1 is smaller than NIP / VR2, the minimum meshing time PBLT can be reduced. Therefore, since the application time of the nip pressure PB (minimum value) in the equation is reduced, the experimental result shown in FIG. + 3% (average value of the number of trials 4). Thus, the minimum engagement time PBLT = 1 [second (NIP / V
R)], the nip pressure PB on the left-hand side of the expression ′ that determines the avoidance of double feed accompanied by the adhesion force is the nip pressure PB in the expression.
By saturating (minimum value) and minimizing, the margin for the adhesion Q on the right side is improved. At the same time, the nip pressure PB on the left-hand side of the equation that determines non-feeding with cohesion is + 3% higher than the intermediate value between the nip pressure PB (highest value) in the equation and the nip pressure PB (lowest value) in the equation. At the same time, the maximum value is in the range of PBLT ≧ 1 [second (NIP / VR)], and the non-sending avoidance performance accompanying the adhesion force is higher than the case of only the configuration with the maximum non-sending avoidance margin. Therefore, it is possible to obtain the sheet feeding performance in the case where the adhesion force acts between the sheets, and also to obtain the sheet feeding performance with a large non-feeding allowance margin.

Next, another embodiment (corresponding to claim 16)
Will be described. The sheet feeding device in the present embodiment is expressed by Expression 17 and Expression
18 at the same time. VF1 = VF2
× 1.2 and VR1 = VR2 × 1.15, the paper to be fed because the feed roller linear speed of the paper to be fed was increased within the application time of the nip pressure PB (minimum value) in the equation And the slip performance of the feed roller 1 was improved, that is, the transport performance was improved. Also, NIP / VR
Since 1 is smaller than NIP / VR2, the minimum meshing time PBLT can also be reduced. Therefore, since the application time of the nip pressure PB (minimum value) in the equation is reduced, the experimental result shown in FIG. , Uniformly improved by + 4.5% (average of the number of trials 4).

Thus, the minimum meshing time PBLT = 1
In [sec (NIP / VR)], the nip pressure PB on the left side of the equation 決 め る that determines the avoidance of double feed with cohesion is saturated with the nip pressure PB (minimum value) in the equation and becomes minimum, and the right side The margin for the adhesion Q is improved. At the same time, the nip pressure PB on the left-hand side of the expression を that determines non-feeding with cohesion is + 4.5% higher than the intermediate value between the nip pressure PB (highest value) in the expression and the nip pressure PB (lowest value) in the expression. At the same time, the maximum in the range of PBLT ≧ 1 [second (NIP / VR)], and the non-sending avoidance performance with cohesive force is obtained by adding the condition of Equation 17 to the configuration with the maximum non-sending avoidance margin. Or, it becomes higher than the case where the condition of Expression 18 is added. Accordingly, it is possible to obtain the sheet feeding performance in the case where the adhesion force acts between the sheets, and also to obtain the sheet feeding performance with a larger non-feeding allowance margin.

Next, another embodiment (corresponding to claim 18)
Will be described. The paper feeder according to the present embodiment is characterized in that the rubber hardness K of the feed roller 1 and the reverse roller 2 complies with the following equation (19). K ≧ 37 ° 19 The experimental results shown in FIG. 7 are for the case where the rubber hardness of the feed roller 1 and the reverse roller 2 is 37 °. When K = 39 ° according to Equation 19, NIP when K = 39 °
Since / VR becomes smaller than NIP / VR when K = 37 °, the minimum meshing time PBLT can also be made shorter. Therefore, since the application time of the nip pressure PB (minimum value) in the equation was reduced, the experimental result shown in FIG.
Nip pressure P, which is the left-hand side value of the expression that determines non-feeding avoidance
B is uniformly + 0.B regardless of the minimum meshing time PBLT.
It was improved by 5% (average of the number of trials 3).

Thus, the minimum engagement time PBLT = 1
In [sec (NIP / VR)], the nip pressure PB on the left side of the equation 決 め る that determines the avoidance of double feed with cohesion is saturated with the nip pressure PB (minimum value) in the equation and becomes minimum, and the right side The margin for the adhesion Q is improved. At the same time, the nip pressure PB on the left-hand side of the expression 決 め る that determines non-feeding with cohesion is + 0.5% higher than the intermediate value between the nip pressure PB (highest value) in the expression and the nip pressure PB (lowest value) in the expression. At the same time, the maximum is in the range of PBLT ≧ 1 [second (NIP / VR)], and the non-sending avoidance performance with the adhesion force is higher than the case of only the configuration having the maximum non-sending avoidance margin. Similarly, K = 30 °, K = 41 °
Was performed, but the nip pressure PB of the left-hand side of the expression 決 め る which determines the non-feeding accompanied by the adhesion force is the nip pressure PB (maximum value) in the expression and the nip pressure PB in the expression, respectively.
(Minimum value) shows -2.1% and + 0.6% from the intermediate value. If K = about 37 °, the performance is almost saturated. Therefore, by setting the rubber hardness, it is possible to obtain the sheet feeding performance in the case where the adhesion force acts between the sheets, and also to obtain the sheet feeding performance with a large margin for avoiding non-feeding.

In each of the above embodiments, the paper feeder and the image forming apparatus provided with the same have been described. However, the present invention can be similarly applied to a flexible sheet-like medium feeder such as a bill or a ticket.

[0086]

According to the invention as set forth in claims 1, 19, 20 and 21, the nip pressure of the nip portion is changed, and the feed driving time in the state where the nip pressure is the lowest is provided. Since the time is set to be longer than the time required for the sheet-shaped medium to pass through the fixed point nip portion, the minimum value condition of the application time of the low pressure value can be given. As a result, while avoiding non-feed due to high nip pressure,
Avoidance of double feeding due to low nip pressure can be ensured, and the margin for avoiding non-feeding and double feeding can be improved. Can be done.

According to the invention described in claim 2, 19, 20, or 22, the nip pressure of the nip portion is changed, and the feeding drive time in the state where the nip pressure is the lowest is set to the sheet. Since the length of the medium is equal to the time required to pass through the nip portion at the fixed point, it is possible to obtain a function having the maximum margin for avoiding non-feeding and further improve the sheet separation performance.

According to the invention of claim 3, 19, 20 or 23, the nip pressure of the nip portion is changed, and the feeding drive time in the state where the nip pressure is the lowest is set to the sheet. The width of the nip portion in the transport direction of the medium is set to be larger than a value obtained by dividing the width of the nip portion by the linear velocity of the reverse roller. To avoid double feed, and to improve the margin for avoiding non-feed and double feed, thereby improving the paper feed separation performance even when a high adhesion force is applied between sheets. it can.

According to the invention as set forth in claim 4, 19, 20 or 24, the nip pressure of the nip portion is changed, and the feeding driving time in the state where the nip pressure is the lowest is set to the sheet. Is equal to the value obtained by dividing the width of the nip in the transport direction of the medium by the linear speed of the reverse roller, so that the function with the maximum margin for avoiding non-feeding can be obtained, further improving the paper feed separation performance. Can be done.

According to the invention as set forth in claim 5, 19, 20 or 25, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotary shaft, and one of each set is provided. The gear has a toothless part in its circumferential direction with no teeth, and the rotation of the rotating shaft is only one at any moment
A feed driving time in a state where the nip pressure of the nip portion is the lowest is set to be longer than a time required for the sheet-shaped medium to pass through the fixed nip portion of the sheet-shaped medium. Because of the configuration, it is possible to reliably avoid double feed due to low nip pressure, while ensuring non-feed avoidance due to high nip pressure,
In addition, it is possible to improve the margin for avoiding the non-feed and the double feed, and to improve the sheet separation performance even when a high adhesion force acts between the sheets.

According to the invention as set forth in claim 6, 1, 20, or 26, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotating shaft, and one of each set is provided. Gear has a toothless portion in the circumferential direction of which there are no teeth, and the rotation of the rotating shaft is only one at any moment.
A configuration in which the gears of a set of gears are meshed with each other, and a feeding drive time in a state where the nip pressure of the nip portion is lowest is equal to a time required for the sheet-shaped medium to pass through a fixed nip portion of the sheet medium. Therefore, the function with the maximum non-feeding allowance margin can be obtained, and the paper feed separation performance can be further improved.

According to the invention of claim 7, 19, 20 or 27, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotating shaft, and one of each set. Gear has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft is caused by engagement of only one set of gears at any moment, and the nip portion Since the feeding drive time in the state where the nip pressure is the lowest is set to be larger than the value obtained by dividing the width of the nip portion in the transport direction of the sheet medium by the linear speed of the reverse roller, a high nip While avoiding non-feeding due to pressure, it is possible to reliably avoid double feeding due to low nip pressure, and it is possible to improve the margin for avoiding non-feeding and double feeding, and high adhesion between sheets. Where work works But it is possible to improve the paper separation performance.

According to the invention of claim 8, 19, 20, or 28, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotating shaft, and one of each set is provided. Gear has a toothless portion in which no teeth are present in the circumferential direction, and the rotation of the rotating shaft is caused by engagement of only one set of gears at any moment, and the nip portion Since the feed driving time in the state where the nip pressure is the lowest is equal to the value obtained by dividing the width of the nip in the conveying direction of the sheet medium by the linear speed of the reverse roller, the non-feeding allowance margin is Can obtain the maximum function, and the paper feed separation performance can be further improved.

According to the ninth, nineteenth or twentieth aspect of the present invention, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotary shaft, and one of each set of gears. Has a missing tooth portion in which no teeth are present in the circumferential direction, and has a configuration in which rotation of the rotating shaft is caused by engagement of only one set of gear teeth at any moment, and from the fulcrum of the rotating shaft. The meshing time of the gear having the missing tooth portion in the pair of the closest drive gear and the driven gear is defined as PBLT,
The width of the nip in the transport direction of the sheet medium is set to NI
P, when the linear velocity of the reverse roller is VR, PBLT
> NIP / VR, it is possible to reliably prevent non-feed due to high nip pressure and to avoid double feed due to low nip pressure.
In addition, it is possible to improve the margin for avoiding the non-feed and the double feed, and to improve the sheet separation performance even when a high adhesion force acts between the sheets.

According to the tenth, nineteenth or twentieth aspect of the present invention, there are at least two or more sets of drive gears and driven gears along the longitudinal direction of the rotary shaft, and one of each set of gears. Has a toothless portion having no teeth in its circumferential direction, and has a configuration in which rotation of the rotating shaft is caused by engagement of only one set of gear teeth at any moment, and from the fulcrum of the rotating shaft. The meshing time of the gear having the missing tooth portion in the pair of the closest drive gear and the driven gear is defined as PBLT,
The width of the nip in the transport direction of the sheet medium is set to NI
P, when the linear velocity of the reverse roller is VR, PBLT
= NIP / VR, the function with the maximum non-sending margin can be obtained, and the paper feed separation performance can be further improved.

According to the eleventh, nineteenth, or twelfth aspect of the present invention, in the feeding device according to the ninth or tenth aspect, when the direction from the fulcrum toward the reverse roller is positive, the distance from the fulcrum to the driven gear can be increased. L is the distance, L2 is the distance from the fulcrum to the center of gravity of the rotary shaft, L3 is the distance from the fulcrum to the bearing on the free end side of the rotary shaft, L4 is the distance from the fulcrum to the reverse roller. The weight at the center of gravity is P
2. The pressure at the bearing is P3, the return force of the torque limiter is TA, the radius of the driven gear is RZ, the radius of the reverse roller is RS, and the nip pressure of the nip is PB.
L> (L2 · P2-L3 · P3) · (RZ /
(RS) / TA relationship is established, so that a positive nip pressure can always be obtained, contact between the reverse roller for avoiding double feeding and the paper to be separated is always guaranteed, and close contact between the papers It is possible to reliably obtain the sheet separation performance when force is applied.

According to the twelfth, twelfth and twelfth aspects of the present invention, in the feeding device according to any one of the ninth to twelfth aspects, the feeding device in the set of the driving gear and the driven gear farthest from the reverse roller is provided. The minimum time in one cycle time consisting of the sum of the meshing time at one continuous tooth portion at the time of feeding driving and the non-meshing time due to the next missing tooth portion is T, and the sheet-like shape is formed from the pair of the feed roller and the reverse roller. When the distance to the next transport roller pair downstream in the transport direction of the medium is DL, and the linear velocity of the feed roller is VF, the relational expression of T ≦ DL / VF is established. 12. At least once between a pair and a next conveying roller pair.
Because the function of paper feed separation in one of the
The reliability of paper feeding can be improved.

According to the thirteenth, nineteenth or twelfth aspect of the present invention, in the feeding device according to the tenth aspect, the distance from the fulcrum of the rotating shaft in the drive gear and the driven gear closest to the reverse roller is LLONG, and the distance is the longest. LSHO indicates the distance from the fulcrum of the rotating shaft in the driven gear and the driven gear.
In the case of RT, it is assumed that in a configuration having only one set of the driving gear and the driven gear, the optimum conveyance performance is obtained at the distance LFRR1 from the fulcrum of the rotary shaft and the optimum separation performance is obtained at the distance LFRR2 from the fulcrum of the rotary shaft. LFR
R1 = (LLONG + LSHORT) / 2, LFRR2
Since the relational expression of = LSHORT is established, it is possible to easily design a configuration having the maximum non-sending avoidance margin.

According to the invention as set forth in claim 14, 19 or 20, in the feeding device as set forth in claim 10, at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear closest to the fulcrum of the rotary shaft. The linear velocity of the feed roller is different from the linear velocity of the feed roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotating shaft,
When the former is VF1 and the latter is VF2, VF1 ≧ VF
Since the relational expression 2 is satisfied, the slip performance for the paper to be fed can be improved, and the paper feed separation performance can be further improved.

According to the fifteenth, nineteenth, or twentieth aspect of the present invention, in the feeding device according to the tenth aspect, the feeding device is configured to perform the feeding driving at the tooth portion of the set of the driving gear and the driven gear closest to the fulcrum of the rotating shaft. The linear velocity of the reverse roller is different from the linear velocity of the reverse roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotating shaft,
When the former is VF1 and the latter is VF2, VR1 ≧ VR
Since the relational expression 2 is satisfied, the application time of the low pressure value for avoiding the double feed accompanied by the close contact force can be reduced, whereby the transportability of the paper to be fed can be improved, and It is possible to obtain the sheet separation performance that can cope with the adhesion.

According to the sixteenth, nineteenth, or twentieth aspect of the present invention, in the feeding device according to the fourteenth aspect, the feed driving at the tooth portion of the set of the driving gear and the driven gear closest to the fulcrum of the rotating shaft is performed. The linear velocity of the reverse roller is different from the linear velocity of the reverse roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum of the rotating shaft,
When the former is VF1 and the latter is VF2, VR1 ≧ VR
Since the configuration satisfying the relational expression 2 is satisfied, the sheet separation performance can be further improved.

According to the invention described in claim 17, 19 or 20, in the feeding device according to any one of claims 9 to 16, the teeth adjacent to the missing tooth portion in the gear having the missing tooth portion. Since the tooth width at the end in the circumferential direction of the portion is set to be smaller than the tooth width of the other teeth, it is possible to reduce noise during paper feed driving and to improve gear durability. Further, disturbance of the nip pressure can be reduced, and a stable sheet feeding and separating function can be obtained.

According to the invention described in claim 18, 19 or 20, in the feeding device according to any one of claims 1 to 17, the feed roller and the reverse roller are formed of rubber, and both rubber hardnesses are set. Is K ≧ 37 °
Is satisfied, it is possible to optimize the contribution to the paper feed separation function from the viewpoint of rubber hardness, and to improve the paper feed separation function.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing the number of sets of a drive gear and a driven gear and a positional relationship.

3A and 3B are diagrams illustrating tooth shapes of a drive gear, wherein FIG. 3A is a diagram illustrating a fulcrum-side drive gear, and FIG. 3B is a diagram illustrating a reverse roller-side drive gear.

FIG. 4 is a timing chart of ON / OFF of a driving gear.

FIG. 5 is a front view of a main part showing a shape of a tooth portion of the drive gear.

FIG. 6 is a main part front view showing a nip width.

FIG. 7 is a graph showing a relationship between a nip pressure and a minimum engagement time.

8A and 8B are diagrams illustrating a drive gear according to the embodiment, in which FIG. 8A is a side view before a missing tooth portion is formed, and FIG. 8B is a front view before a missing tooth portion is formed.

FIG. 9 is a diagram showing a pattern of a missing tooth portion of a drive gear.

FIG. 10 is a graph showing a relationship between a nip pressure and a minimum engagement time in the example.

FIG. 11 is a schematic front view of a copying machine as an image forming apparatus according to the embodiment.

FIG. 12 is a schematic front view of another embodiment.

13 is a schematic front view showing one cycle time of a combination of a tooth portion and a missing tooth portion adjacent thereto in the embodiment shown in FIG.

FIG. 14 is a front view of a main part of an FRR type sheet feeding device.

FIG. 15 is a force relation diagram centering on a reverse roller rotating shaft in the FRR type sheet feeding device.

FIG. 16 is a force relation diagram centered on a fulcrum in the FRR type sheet feeding device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 feed roller 2 reverse roller 5 torque limiter 6 paper as sheet-like medium 8 rotating shaft 10 fulcrum-side driven gear as driven gear 11 reverse-roller-side driven gear as driven gear 12 fulcrum-side driving gear 12a, 12c as driving gear , 12e, 12g, 12i Tooth portion 12b, 12d, 12f, 12h, 12j Tooth missing portion 13 Reverse roller side drive gear 13b, 13d, 13f, 13h, 13j as drive gear Tooth portion 13a, 13c, 13e, 13g, 13i Missing part

Claims (28)

[Claims] 1. A feed roller for conveying a sheet medium, a cantilevered rotary shaft having a driven gear, and a free end side of the rotary shaft provided via a torque limiter so as to be rotatable in normal and reverse directions. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. A feed device for obtaining rotation in the conveyance direction and rotation in the return direction with respect to the sheet-shaped medium, wherein the nip pressure of the nip portion is changed, and the feed driving time in a state where the nip pressure is the lowest But,
A feeding device, wherein the time is set to be longer than the time required for the fixed point of the sheet-shaped medium to pass through the nip portion. 2. A feed roller for transporting a sheet-like medium, a cantilevered rotary shaft having a driven gear, and a free end side of the rotary shaft provided via a torque limiter so as to be rotatable forward and reverse. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. A feeding device for obtaining rotation in the conveyance direction and rotation in the return direction with respect to the sheet-shaped medium, wherein the nip pressure of the nip portion is changed, and the feeding drive time in a state where the nip pressure is the lowest But,
The feeding device is characterized in that the feeding time is equal to the time required for the fixed point of the sheet medium to pass through the nip portion. 3. A cantilevered rotary shaft having a feed roller for transporting a sheet-like medium, a driven gear, and a free end side of the rotary shaft via a torque limiter so as to be rotatable forward and reverse. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. A feeding device for obtaining rotation in the conveyance direction and rotation in the return direction with respect to the sheet-shaped medium, wherein the nip pressure of the nip portion is changed, and the feeding drive time in a state where the nip pressure is the lowest But,
A feeding device, wherein a width of the nip portion in a conveying direction of the sheet-like medium is set to be larger than a value obtained by dividing by a linear speed of the reverse roller. 4. A cantilever type rotary shaft having a feed roller for conveying a sheet-like medium, a driven gear, and a free end side of the rotary shaft via a torque limiter so as to be rotatable in normal and reverse directions. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. A feeding device for obtaining rotation in the conveyance direction and rotation in the return direction with respect to the sheet-shaped medium, wherein the nip pressure of the nip portion is changed, and the feeding drive time in a state where the nip pressure is the lowest But,
A feeding device, wherein a width of the nip portion in a conveying direction of the sheet-like medium is equal to a value obtained by dividing the width of the nip portion by a linear speed of the reverse roller. 5. A cantilever type rotary shaft having a feed roller for transporting a sheet-like medium, a driven gear, and a free end side of the rotary shaft via a torque limiter so as to be rotatable forward and reverse. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. In a feeding apparatus for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along the longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feeding drive time in a state where the nip pressure of the nip portion is the lowest, and a time required to pass through the nip portion at a fixed point of the sheet-shaped medium A feeding device characterized by being set larger. 6. A cantilever rotary shaft having a feed roller for transporting a sheet-like medium, a driven gear, and a free end side of the rotary shaft provided via a torque limiter so as to be rotatable in normal and reverse directions. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. In a feeding device for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along a longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feed drive time in a state where the nip pressure of the nip portion is the lowest, and a time required for the sheet-shaped medium to pass through the nip portion at a fixed point, having a configuration caused by the meshing of the teeth of the set of gears. A feeding device, characterized in that: 7. A cantilever type rotating shaft having a feed roller for conveying a sheet-like medium, a driven gear, and a free end side of the rotating shaft which is rotatably and reversely rotatable via a torque limiter. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear; the reverse roller is driven by a change in frictional force according to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller; In a feeding device for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along a longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feed drive time in a state where the nip pressure of the nip portion is the lowest, and the width of the nip portion in the transport direction of the sheet-like medium is reduced. The feeding device is set to be larger than a value obtained by dividing by a linear speed of the reverse roller. 8. A cantilever type rotary shaft having a feed roller for transporting a sheet-like medium, a driven gear, and a free end side of the rotary shaft via a torque limiter so as to be rotatable forward and reverse. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear; the reverse roller is driven by a change in frictional force according to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller; In a feeding device for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along the longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feed drive time in a state where the nip pressure of the nip portion is the lowest, and the width of the nip portion in the transport direction of the sheet-like medium is reduced. A feeding device characterized by being equal to a value obtained by dividing by a linear speed of the reverse roller. 9. A cantilever rotary shaft having a feed roller for transporting a sheet-like medium, a driven gear, and a free end side of the rotary shaft via a torque limiter so as to be rotatable forward and reverse. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear; the reverse roller is driven by a change in frictional force according to the number of sheets of the sheet-like medium entering the nip portion between the feed roller and the reverse roller; In a feeding device for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along a longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feed drive in a tooth portion having the smallest number of teeth of a gear having a toothless portion in a set of a drive gear and a driven gear closest to a fulcrum of the rotary shaft, the configuration being caused by meshing between tooth portions of a set of gears; The engagement time at the time of PBL
T, wherein the width of the nip portion in the transport direction of the sheet medium is NIP, and the linear speed of the reverse roller is VR, and a relational expression of PBLT> NIP / VR holds. 10. A feed roller for transporting a sheet-like medium, a cantilevered rotating shaft having a driven gear, and a free end side of the rotating shaft provided via a torque limiter so as to be rotatable in normal and reverse directions. A reverse gear that is in pressure contact with the feed roller, and a drive gear that meshes with the driven gear. In a feeding apparatus for obtaining rotation in a conveyance direction and rotation in a return direction with respect to the sheet-shaped medium, there are at least two or more sets of the drive gear and the driven gear along the longitudinal direction of the rotation shaft, and each set One of the gears has a toothless portion in which no teeth exist in the circumferential direction, and the rotation of the rotating shaft is only one at any moment.
A feed drive in a tooth portion having the smallest number of teeth of a gear having a toothless portion in a set of a drive gear and a driven gear closest to a fulcrum of the rotary shaft, the configuration being caused by meshing between tooth portions of a set of gears; The engagement time at the time of PBL
T, wherein the width of the nip portion in the transport direction of the sheet-like medium is NIP, and the linear velocity of the reverse roller is VR, and a relational expression of PBLT = NIP / VR holds. 11. The feeding device according to claim 9, wherein a distance from the fulcrum to the driven gear when the direction from the fulcrum toward the reverse roller is positive is L, and the rotation shaft is The distance to the center of gravity is L2, the distance from the fulcrum to the bearing on the free end side of the rotary shaft is L3, the distance from the fulcrum to the reverse roller is L4, the own weight at the center of gravity of the rotary shaft is P2, and the bearing is Pressure at P3,
When the return force of the torque limiter is TA, the radius of the driven gear is RZ, the radius of the reverse roller is RS, and the nip pressure of the nip is PB, L> (L2 · P2-L3 · P3) · ( RZ / RS) / T
A feeding device, wherein the relational expression of A is satisfied. 12. The feeding device according to claim 9, wherein a set of a driving gear and a driven gear farthest from the reverse roller has one continuous tooth portion at the time of feeding driving. The minimum time in one cycle time consisting of the sum of the meshing time and the non-meshing time due to the next missing tooth portion is T,
When the distance from the pair of the feed roller and the reverse roller to the next pair of transport rollers downstream of the sheet-like medium in the transport direction is DL, and the linear velocity of the feed roller is VF, the relational expression of T ≦ DL / VF is given by A feeding device characterized by being satisfied. 13. The feeding device according to claim 10, wherein a distance between a fulcrum of the rotary shaft in the drive gear and the driven gear closest to the reverse roller is LLONG, and the distance between the drive gear and the driven gear in the farthest drive gear and the driven gear is LLONG. When the distance from the fulcrum is LSHORT, the optimum transfer performance in a configuration having only one set of drive gears and driven gears is obtained at the distance LFRR1 from the fulcrum of the rotary shaft, and the optimum separation performance is the fulcrum of the rotary shaft. Distance from LFRR2
Where LFRR1 = (LLONG + LSHORT) / 2 LFRR2 = LSHORT. 14. A feed device according to claim 10, wherein the linear velocity of said feed roller at the time of feed driving at a tooth portion of a set of a driving gear and a driven gear closest to a fulcrum of said rotary shaft is equal to said rotary shaft. Different from the linear velocity of the feed roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum, when the former is VF1 and the latter is VF2, the relational expression of VF1 ≧ VF2 holds. A feeding device characterized by the above-mentioned. 15. The feeding device according to claim 10, wherein a linear speed of said reverse roller at the time of feed driving at a tooth portion of a set of a driving gear and a driven gear closest to a fulcrum of said rotary shaft is equal to said rotary shaft. Different from the linear speed of the reverse roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum, when the former is VF1 and the latter is VF2, the relational expression of VR1 ≧ VR2 holds. A feeding device characterized by the above-mentioned. 16. The feeding device according to claim 14, wherein the linear speed of said reverse roller at the time of feeding driving at a tooth portion of a set of a driving gear and a driven gear closest to a fulcrum of said rotating shaft is equal to said rotating shaft. Unlike the linear speed of the reverse roller at the time of feeding driving at the tooth portion of the set of the driving gear and the driven gear farthest from the fulcrum, when the former is VF1 and the latter is VF2, the relational expression of VR1 ≧ VR2 holds. A feeding device characterized by the above-mentioned. 17. The feeding device according to claim 9, wherein a tooth width of a tooth portion adjacent to the toothless portion of the gear having the toothless portion has another tooth width. A feeding device characterized in that the feeding device is set to be narrower than the tooth width. 18. The feeding device according to claim 1, wherein the feed roller and the reverse roller are formed of rubber, and when both rubber hardnesses are K, K ≧ 37 °. A feeding device, wherein a relational expression holds. 19. A cantilever type rotary shaft having a feed roller for transporting a sheet as a sheet-shaped medium, a driven gear, and a free end side of the rotary shaft capable of rotating forward and backward through a torque limiter. A reverse gear provided in pressure contact with the feed roller, and a drive gear meshing with the driven gear. The reverse roller is driven by a change in frictional force corresponding to the number of sheets entering the nip portion between the feed roller and the reverse roller. 19. A sheet feeding apparatus for obtaining rotation of the sheet in the conveying direction and rotation of the sheet returning direction, wherein the sheet feeding apparatus has the configuration of the sheet feeding apparatus according to claim 1. apparatus. 20. An image in which an electrostatic latent image formed on an image carrier is developed by a developing means into a toner image, and the toner image is transferred to a sheet medium fed by a sheet feeding device. An image forming apparatus, wherein the sheet feeding device has the configuration of the feeding device according to any one of claims 1 to 18. 21. A sheet is fed to a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilevered rotary shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, A paper feeding method, wherein a nip pressure of a nip portion is changed, and a paper feed driving time in a state where the nip pressure is the lowest is set to be longer than a time for passing the fixed point of the paper through the nip portion. . 22. A sheet is fed to a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilevered rotating shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, A paper feeding method, wherein a nip pressure of a nip portion is changed, and a paper feeding driving time in a state where the nip pressure is the lowest is equal to a time when the paper passes through the nip portion at a fixed point of the paper. 23. A sheet is fed into a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilever type rotating shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, The nip pressure of the nip portion is changed, and the paper feed drive time in the state where the nip pressure is the lowest is larger than the value obtained by dividing the width of the nip portion in the paper conveyance direction by the linear speed of the reverse roller. A paper feeding method characterized by setting. 24. A sheet is fed into a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilever type rotary shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, The nip pressure of the nip portion is changed, and the paper feed drive time in the state where the nip pressure is the lowest is equal to the value obtained by dividing the width of the nip portion in the paper transport direction by the linear speed of the reverse roller. Feeding method characterized by performing. 25. A sheet is fed to a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilevered rotating shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, At least two or more sets of driving gears and driven gears for rotating the rotating shaft are provided along the longitudinal direction of the rotating shaft, and one of the gears in each set has no teeth in its circumferential direction. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion, and the paper feed driving time in the state where the nip pressure of the nip portion is the lowest is the time for passing the fixed point of the paper through the nip portion. A paper feeding method characterized by being set larger. 26. A sheet is fed to a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilever type rotating shaft via a torque limiter; A paper feeding method for feeding the sheets one by one by obtaining rotation of the reverse roller in the conveyance direction and rotation of the return direction with respect to the sheet by changing the frictional force according to the number of sheets entering the nip portion, and feeding the sheets one by one. At least two or more sets of driving gears and driven gears for rotating the rotating shaft are provided along the longitudinal direction of the rotating shaft, and one of the gears in each set has no teeth in its circumferential direction. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion, and the paper feed driving time in the state where the nip pressure of the nip portion is the lowest is the time for passing the fixed point of the paper through the nip portion. A paper feeding method characterized by being equal to: 27. A sheet is fed to a nip portion between a feed roller for conveying the sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilever type rotary shaft via a torque limiter, A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, At least two or more sets of driving gears and driven gears for rotating the rotating shaft are provided along the longitudinal direction of the rotating shaft, and one of the gears in each set has no teeth in its circumferential direction. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined by the width of the nip portion in the transport direction of the paper. Is set to be larger than a value obtained by dividing by the linear velocity of the reverse roller. 28. A sheet is fed to a nip portion between a feed roller for conveying a sheet and a reverse roller rotatably and reversely provided on a free end side of a cantilever type rotating shaft via a torque limiter, A paper feeding method for feeding the sheets one by one by obtaining a rotation of the reverse roller in a conveyance direction and a rotation of a return direction with respect to the sheet by changing a frictional force according to the number of sheets entering the nip portion, At least two or more sets of driving gears and driven gears for rotating the rotating shaft are provided along the longitudinal direction of the rotating shaft, and one of the gears in each set has no teeth in its circumferential direction. The nip pressure of the nip portion is changed as a configuration having a missing tooth portion, and the paper feed driving time in a state where the nip pressure of the nip portion is the lowest is determined by the width of the nip portion in the transport direction of the paper. And a value obtained by dividing by a linear velocity of the reverse roller.