JP2889787B2 - Paper feeder with differential pulley reduction mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder having a differential pulley speed reduction mechanism, and more particularly, to a paper feeder suitable for use in a large capacity cassette elevator of a copying machine or a printer.
A wrist (also referred to as a paper feed tray) on which the upper surface is substantially flat and paper is placed, a frame surrounding the wrist so that the wrist can move up and down, a wrist supporting the wrist from the side, and It has a differential pulley deceleration mechanism that moves up and down, and prints paper (natural paper, synthetic paper) on a paper recording device that records codes, characters, images, etc. on paper such as copying machines, printers, facsimile machines, and various printing devices. , And various sheet-shaped materials).

[0002]

2. Description of the Related Art There is a demand for copying machines and printers to copy and print on a large number of sheets. In response to this request, a large-capacity cassette elevator that continuously supplies a large number of sheets to a copying machine or the like without cutting the sheets is used. FIG. 7 is a perspective view of a drive unit configuration of an elevator elevating device used in a conventional large-capacity cassette elevator.

In the elevator elevating device shown in FIG. 7, guide members b which extend vertically and are provided on both right and left sides of a list a on which sheets are placed with respect to the sheet supply direction are provided. On the lower surface of the wrist a, a support member c for supporting the wrist a is provided over the left and right. Guide rollers d that fit into and slide into the rails of the guide member b are rotatably provided on both left and right sides of the wrist a.
Further, a belt member e suspending the wrist a is fixed by a fixing member f. The belt member e is directed upward through a roller g provided above the wrist a, is guided downward, and is wound up by a winding pulley h1 of a winding shaft h. The belt member e is wound right and left on the winding pulley h1 at the same time, and the wrist a is moved up and down along the guide member b. The driving force at the time of the elevation is given from the motor k via a motor pinion, a spur gear reduction unit i having a two-stage gear, a worm gear, and a worm gear reduction unit j having a worm wheel.

[0004]

However, in the conventional elevator elevating device, since the reverse rotation prevention mechanism due to the friction of the worm reduction mechanism is used as the self-weight drop prevention mechanism for the wrist a, the power transmission efficiency is poor (approximately). 4
0%) and needs to be improved.

Further, since the wrist a is lowered at a high speed at the time of initial setting and at the time of replenishment of paper, there is a problem that a loud noise is generated as compared with the meshing part of the spur gear reduction unit i and the worm gear reduction unit j. There is a need to. Also,
Since there is a risk that the lifting device will shake and be damaged when the copier or printer is moved or transported, the conventional method requires special fixing, and the fixing work is complicated and requires improvement. It is.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to greatly improve transmission efficiency, to have a reverse rotation preventing mechanism, and to reduce noise during high-speed ascent and descent. An object of the present invention is to provide a sheet feeder having a differential pulley speed reduction mechanism which does not need to be specially fixed at the time of transfer and transportation.

[0007]

The present invention has the following structure to achieve the above object. That is, the present invention provides a list on which an upper surface is substantially flat and paper is placed on the upper surface, a frame surrounding the list such that the list can move up and down, each pulley operates in substantially the same plane, and And a differential pulley deceleration mechanism for moving the paper up and down in the frame while supporting the paper from the side, and feeding the paper to the paper surface recording device. First and second pulleys movably provided, third and fourth pulleys rotatably provided at two horizontally separated portions below the frame, and the third and fourth pulleys below the frame. Fifth and sixth pulleys provided between the four pulleys, and two locations which are horizontally separated from the support side surface of the wrist and located inside the locations where the first and second pulleys are provided. And the center of the two places 7 provided at, and the pulley of the eighth and ninth, the first
Wraps around the pulley and goes downward to the seventh pulley, and goes to the eighth pulley in one direction substantially along the side surface of the wrist via the seventh pulley,
Via the pulley and heading upward to the second pulley, wrapping around the second pulley and lowering the fourth pulley
Toward the sixth pulley in the other direction along the side of the wrist via the fourth pulley,
Via the sixth pulley, upward toward the ninth pulley, wind around the ninth pulley, downward toward the fifth pulley, and via the fifth pulley in the other direction The difference between the peripheral speed of the belt member and the belt member of the fifth and sixth pulleys, which is directed toward the third pulley and upward via the third pulley, toward the first pulley, is increased. And a peripheral speed difference driving means for driving the sheet feeding device.

[0008]

In the present invention, the speed reduction mechanism is constituted by a differential pulley speed reduction mechanism mainly comprising a pulley and a belt member. Therefore, transmission efficiency is greatly increased (about 80 to 95%).
Be improved. The reverse rotation function for preventing the wrist from dropping due to its own weight is performed by reducing the frictional resistance of the pulley bearing due to the difference between the peripheral speeds of the fifth and sixth pulleys, that is, the return reaction force due to the difference in the diameter of the pulley of the peripheral speed difference driving means. By setting a large value, a reverse rotation prevention function can be provided.

The speed reduction mechanism of the present invention is a differential pulley speed reduction mechanism that does not use gears. In this speed reduction mechanism, the noise caused by the pulley and the belt is very small as compared with the speed reduction mechanism including the spur gear and the worm gear. Therefore, the speed reduction mechanism of the present invention is a low-noise speed reduction mechanism, so that the noise is reduced at the time of ascending and descending at a high speed. For example, when the list is rapidly lowered at the time of initial setting and at the time of refilling paper, the noise is very small. Also, the wrist is hung up and down by the belt member, so that the copying machine and
There is no risk of the lifting device swinging and being damaged during transport, and there is no need to fix it specially.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a differential pulley reduction mechanism for raising and lowering a wrist of a sheet feeding device according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of a control system and operation of the paper feeding device, and FIG. 3 is an explanatory diagram of an example in which the paper feeding device is used in a copier and a printer. It can be used for a paper surface recording device. In the following, a direction perpendicular to the supply direction of the paper (for example, copy paper) on the upper surface of the list 22 is referred to as the width direction of the list 22.

As shown in FIG. 1, the paper feeding device includes a wrist 22 having a substantially flat upper surface and a sheet placed thereon.
A frame 30 (only a pulley fixing portion is shown) surrounding the wrist 22 so that the wrist 22 can move up and down, and the wrist 22 is supported from a side surface (end surface in the width direction) and is moved up and down within the frame 30 as follows. A differential pulley speed reduction mechanism for supplying paper to a paper surface recording device such as a copying machine or a printer.

That is, first and second pulleys 20 and 15 are rotatably provided at two locations separated from each other in the horizontal direction above the frame 30. In addition, third and fourth pulleys 21 and 14 are rotatably provided at two locations separated in the horizontal direction below the frame 30. Fifth and sixth pulleys 10 and 7 are provided between the third and fourth pulleys 21 and 14 below the frame 30.

The first and second pulleys 20 and 15 are horizontally separated from the supporting side surface of the wrist 22 and are separated from each other.
The seventh, eighth, and ninth pulleys 19 are located at two locations located inside the location where the
16 and 13 are provided.

Wrapping around the first pulley 20 and heading downward to the seventh pulley 19, in one direction substantially along the side surface of the wrist 22 via the seventh pulley 19 (the paper supply direction) It goes to the 8th pulley 16, goes up via the 8th pulley 16 to the 2nd pulley 15, winds around the 2nd pulley 15, and goes down to the 4th pulley 14. ,
Via the fourth pulley 14, heading toward the sixth pulley 7 in the other direction along the side surface of the wrist 22, heading upward via the sixth pulley 7 toward the ninth pulley 13, 9, goes down to the fifth pulley 10, goes through the fifth pulley 10, goes in the other direction to the third pulley 21, goes through the third pulley 21. Then, the first timing belt 12 is stretched between the pulleys so as to head upward to the first pulley 20.

The fifth and sixth pulleys 10 and 7 are respectively provided with differential pulleys 9 and 6 which are coaxial and close to each other and have different diameters. The second timing belt 8 is stretched. The differential pulleys 6 and 9 and the second timing belt 8 constitute a peripheral speed difference driving unit that drives the fifth and sixth pulleys 10 and 7 to generate a difference in peripheral speed. The respective pulleys are disposed substantially symmetrically on both sides in the width direction of the wrist 22. In the following, list 22
The left component is denoted by L, and the right component is denoted by R. However, the peripheral speed difference driving means is provided only on the left side in the width direction of the wrist 22. These are examples of the arrangement of the differential pulley mechanism of the present invention, and the mechanism can be arranged at any position or both sides of the side surface of the wrist.

(Configuration of Wrist Driving Unit) Below the wrist 22, the motor 1 and the shafts 5 and 1 extending in the width direction of the wrist 22
1 is provided. The power of the motor 1 is transmitted to the pulley 4 fixed to the shaft 5 by the pulley 2 fixed to the shaft of the motor 1 and the timing belt 3, and the shaft 5 is driven by the pulley 4. The left and right sixth pulleys 7L and 7R are fixed to both ends of the shaft 5, and the power of the motor 1 is divided into two by the shaft 5 and transmitted to the pulleys 7L and 7R.

The pulley 7R drives the following pulleys provided on the right side of the wrist 22 by the first timing belt 12R. In other words, what is driven is the pulley 14
R, pulley 15R, pulley 16R, pulley 17
R, pulley 18R, pulley 19R, pulley 20
R, pulley 21R, pulley 10R, and pulley 13R, and pulleys 17R and 18R correspond to pulley 1
6R and the first pulley wound around the lower part of the pulley 16R and the pulley 19R, being disposed between the pulley 19R.
Is wound around the upper part of the timing belt 12R. The pulley 16R and the pulley 19R are coaxially connected to the pulley 2R.
4R and pulley 25R are fixed, and timing belt 2
3R causes the pulley 24R and the pulley 25R to rotate in synchronization with each other.
6R and pulley 19R rotate synchronously.

The pulley 7L is connected to the pulley 7R.
Similarly, the following pulleys on the left side of the wrist 22 are driven by the timing belt 12L. In other words, the driven components are the pulley 14L, the pulley 15L, the pulley 16L, the pulley 17L, the pulley 18L, the pulley 1
9L, pulley 20L, pulley 21L, pulley 10
L and a pulley 13L, and pulleys 17L and 18
L is disposed so as to be sandwiched between the pulley 16L and the pulley 19L, and winds the first timing belt 12L wound around the lower part of the pulley 16L and the pulley 19L on the upper part. A pulley 24L and a pulley 25L are fixed coaxially to the pulley 16L and the pulley 19L, and the pulley 24L and the pulley 25L rotate in synchronization with each other by the timing belt 23L. Therefore, the pulley 16L and the pulley 19L are Rotate synchronously.

(Arrangement and Configuration of Pulley for Differential Output) In FIG. 1, a differential output section is arranged on the left side of the wrist 22.
The differential pulley 6L and the pulley 7L are coaxially fixed to the shaft 5, and are integrated in a stepped structure having different diameters. The pulley 10L is fixed to both ends of the shaft 11 together with the pulley 10R. The pulley 9L is a pulley 1
It is coaxial with 0L. Differential pulley 6L and differential pulley 9
As for L, the timing belt 8L is wrapped around and outputs differentially. Further, the diameters D ₆ and D ₉ of the differential pulleys 6L and 9L are set to D ₆ <D ₉ (D ₆ > D ₉ is also possible).

Although the above differential output section is provided only on the left side of the list 22, two sets of the differential output section can be used at both ends in the width direction of the list 22. Thereby, the shaft 5 and the shaft 11
The difference between the left and right due to the torsion can be minimized.

(Control System of Paper Feeding Apparatus) As shown in FIG. 2, the paper feeding apparatus has a controller EC for controlling the operation thereof, and the controller EC has a start button switch 35. An upper limit switch (LS-1) 31 for detecting the upper surface of the stacked sheets 34 is provided above the list 22, and a sheet detection switch (for detecting the presence or absence of the sheet 34 on the list 22) is provided below the list 22. LS-2) 32 is provided. Below the wrist 22, a lower limit switch (LS-3) 33 for detecting the falling end of the wrist 22 and the motor 1 are provided. Above the wrist 22, a pickup roller 40 that rotates in contact with the upper surface of the paper 34 to pick up the paper 34 and feeds the paper 34 in the supply direction, and supports the pickup roller 40 rotatably at one end and the other end. A roller arm 41 swinging to the center, a paper feed roller 42 for feeding out the picked-up paper 34 in the supply direction, and a paper 3 to be sent out
Retard roller 4 to limit 4 to one by one
3 are provided. Further, as shown in FIG. 3, the paper feeding device of the embodiment can be disposed on the paper supply side of a copying machine or a printer. Since the configuration and operation of the copying machine and the like are well known, a description thereof will be omitted.

(Operating Principle of Differential Pulley) In the present invention, a well-known moving pulley principle is used as a differential mechanism. 4 and 5 illustrate the differential mechanism of the moving pulley. In FIG. 4, it is assumed that the front side of the belt B wrapped around the pulley D is sent to the left at a speed V1 and the other side is pulled to the right at a speed V2. The speed Vs of the carriage S that supports the pulley D at this time is as follows: Vs = (V2−V1) / 2 (1) A generally known moving pulley is a special case where one end of the belt B is fixed and V1 = 0 as shown in FIG. 5, and Vs = (V2) / 2.

(Related Expressions of Differential Pulley Speed Reduction Mechanism) In the embodiment shown in FIG. 1, if the dimensions and conditions of each part are as follows, the following expression is established. Shaft 5 rotation speed = N ₅ Pulley 6L diameter = D ₆ Pulley 7L (7R) diameter = D ₇ Pulley 9L diameter = D ₉ Pulley 10L (10R) = D ₁₀ Pulley 13L (13R) = D ₁₃ List 22 Elevating speed = V _{twenty two}

| D ₆ −D ₉ |> 0 & D ₇ = D ₁₀
= When D _13, for the speed reduction ratio R and the lifting speed V _22, the following expression holds. R = (1/2) × | (D ₆ −D ₉ ) | / D ₆ (2) V ₂₂ = (1/2) × (D ₇ / D ₉ ) × π × N ₅ × (D ₉₋ D ₆ ) (3) As a result, as shown in equation (3), 1 / (1) of the difference between the peripheral velocities is obtained.
The speed reducer is capable of moving the wrist 22 up and down at a feed speed of 2.

(Function and role of differential reduction mechanism of paper feeder)
The differential pulley reduction mechanism of the paper feeder is based on the principle of the differential pulley, and the respective roles and functions will be described with reference to FIGS. 6 and 1 showing the configuration of the differential pulley reduction mechanism. . The power transmitted from the motor pulley 2 to the pulley 4 via the belt 3 by the motor 1 is transmitted to the left and right driving pulleys 7L and 7R of the shaft 5.

The pulley diameter of the differential pulley 6L is set so that a peripheral speed difference is generated between the differential pulley 6L and the differential pulley 9L in advance (Example D).
₉ <D ₆ , note D ₉ > D ₆ holds true). These differential pulleys 6L and 9L are connected to a timing belt 8L.
, A speed difference is generated between (the pulleys 7L and 7R: pulleys 13L and 13R) and (the pulleys 10L and 10R: pulleys 13L and 13R).
Due to this speed difference, pulleys 13L and 13R, 1R attached to the wrist 22 via belts 12L and 12R.
6L and 16R, 17L and 17R, 18L and 18
R, 19L and 19R are operated as moving pulleys to raise and lower the wrist 22. Therefore, the paper feeding apparatus of the present embodiment can pick up and feed paper one by one on the list 22 by appropriate selection of the reduction ratio. In addition, the list 22 can be listed little by little according to the amount of paper used, so that paper can always be fed from a fixed position during paper feeding.

(Reverse rotation preventing function of differential pulley reduction mechanism and improvement of transmission efficiency) In the present invention, a gear reduction section such as a worm gear having a low transmission efficiency (about 40%) is eliminated, and a high transmission efficiency (about 80%) is eliminated. ９５95%) The transmission efficiency is improved by employing the differential pulley reduction mechanism. When the return reaction force Tr is considered by the differential pulley reduction mechanism, the following relationship is obtained. Tr = [(1/2) × (D ₉ −D ₆ ) / D ₉ ] × W (4) where W: list load weight (list weight + paper weight), and return reaction force is Tr [kg .Mm]. The total friction force Tμ of the pulley shaft has the following relationship.

(Equation 1) However, d _n: pulley shaft diameter D _n: pulley diameter mu: shank friction coefficient F _n: bearing surface load _{n (1 2 ...... 10 11.} ...): Bearing. Here, even if the reduction ratio is set to a large value, the reverse rotation preventing function operates as long as the total friction force Tμ of the pulley shaft exceeds the return reaction force Tr due to its own weight (wrist weight in a loaded state) W (Tμ> Tr). Is set as such, a reverse rotation preventing function with good transmission efficiency can be obtained. That is, F
_n (bearing surface load) is generated by listing the load weight W, this list load weight W transmitted by the timing belt 12 is transferred to the inner diameter d _n of the pulley through the outer diameter D _n of the pulley. The frictional force between the pulley shaft and the inner diameter of the pulley caused by this force is F _n × μ. Further, the friction torque generated at this time is T _n = (d _n / D _n ) × F _n × μ. In the above equation (5), these friction torques are generated at the respective bearing portions of the timing belt 12, and the sum of the friction torques is calculated to obtain the total friction force Tμ.

(Quiet return during quick return) The list 22 is lowered to the lowest position at the time of initial setting and at the time of replenishment of copy paper.
In raising and lowering work for raising the wrist 22 to a predetermined position after picking up the wrist 22, the noise of the differential pulley reduction mechanism is much smaller than that of the worm reduction gear or the spur gear.

Since the wrist 22 is suspended vertically by the pulleys 15 and 20 and the pulleys 7 and 10, the lifting / lowering unit is shaken when the copying machine and the printer of the main body are relocated and transported. There is no possibility that a problem such as the list 22 will occur, and the list 22 does not need to be fixed.

(Pulley arrangement for downsizing the lifting unit) In the differential pulley reduction mechanism, pulleys 16 and 19 are used.
Between the pulley 13 and the pair of pulleys 17 and 1
8 and the pair of pulleys 17 and 18 are arranged on both side surfaces of the wrist 22 in the width direction. Therefore, the lifting part of the wrist 22 has a small configuration.

Next, the operation of the embodiment will be described. (Fixed Position Feeding Operation) The fixed position feeding operation of the paper feeding apparatus will be described with reference to FIGS. 1, 2, and 6. FIG. The motor 1 is started in the CCW direction shown in FIG. 1 or FIG.
→ The list 22 rises. → The paper 34 rises together with the list 22, and the upper limit switch 31 is turned on. → Motor 1 stops. → The list 22 stops.

When the paper feed timing comes, the controller E
In response to the instruction of C, the pickup roller 40 of the main body operates to feed a required amount of copy paper one by one. → The paper position goes down. → The upper limit switch 31 is turned off. → The motor 1 is restarted by the instruction of the controller EC, and the list 22 rises. → When the upper limit switch 31 of the sheet 34 is turned on, the list 22 stops rising. By this repetition, copy paper can always be fed little by little from the fixed position one by one according to the used amount.

(Paper Feeding / Supplying Operation) The operation at the time of sheet feeding will be described with reference to FIGS. 1, 2 and 6. FIG. When all the sheets 34 on the list 22 are conveyed from the upper surface of the list 22 by the home position feeding operation, the sheet detection limit switch 3
2 turns off. → The motor 1 starts in the CW direction according to the instruction from the controller EC. → The list 22 descends.
→ The lower limit switch 33 turns ON. → Motor 1
Stops. → The list 22 stops at the lowest position.
At this lowest position, the paper 34 is put on the list 22 and replenished. → After the setup is completed, press the start button switch 35 on the controller EC side. → Motor 1 is CC
Start in the W direction. → The list 22 rises. → Paper 3
4 rises with list 22 and upper limit switch 31
Turn ON. → Stop motor 1. → The list 22 stops, and the operation of feeding the copy paper is completed.

(Initial Setting Operation) The initial setting operation of the paper supply apparatus will be described with reference to FIG. Main unit power ON
Sometimes the initial setting operation is performed when restarting after an emergency stop. OFF of lower limit switch 33 and paper detection switch 32
The initial setting operation is performed when is turned on. Motor 1
Start in the W direction. → The list 22 descends. → The lower limit switch 33 turns ON. → Stop motor 1. → The list 22 stops at the lowest position. At this position, the motor 1 is again set to C
Start in the CW direction. → The list 22 rises. → The paper 34 rises with the list 22 and the upper limit switch 3
Turn 1 ON. → Stop motor 1. → List 22
Stops. The list 22 after the ascending is stopped, and the copy paper initial setting operation is completed.

In the above embodiment, an example was shown in which the paper supply apparatus of the present invention was used for a copying machine and a printer. However, the present invention is not limited to this and can be used for various other recording apparatuses. .

[0036]

As described above, according to the present invention, the speed reduction mechanism is constituted by a differential pulley speed reduction mechanism mainly including a pulley and a belt member. Therefore, the transmission efficiency is greatly improved (about 80 to 95%) as compared with the conventionally used worm gear reduction mechanism having a low transmission efficiency (40%). The reverse rotation function for preventing the wrist from falling due to its own weight is based on the difference between the peripheral speeds of the fifth and sixth pulleys, that is, the friction of the pulley bearing part due to the return reaction force due to the difference in the diameter of the pulley of the peripheral speed difference driving means. By setting the resistance large, a reverse rotation preventing function can be provided. The speed reduction mechanism of the present invention is a differential pulley speed reduction mechanism that does not use gears. The noise generated by the pulley and the belt is very small as compared with the speed reduction mechanism including the spur gear and the worm gear. Therefore, the speed reduction mechanism of the present invention is a low-noise speed reduction mechanism. For example, when the list is rapidly lowered at the time of initial setting and at the time of refilling paper, the noise is very small. Further, since the wrist is suspended in the vertical direction by the belt member, there is no danger that the lifting / lowering device portion will be shaken and damaged when the copying machine or the printer of the main body is moved or transported, and it is not necessary to fix the wrist specially.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a differential pulley speed reduction mechanism of a paper feeding apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the elevating operation of the paper supply device of the present invention.

FIG. 3 is an explanatory diagram of a usage example of the paper supply device of the present invention.

FIG. 4 is an explanatory diagram of a differential pulley speed reduction mechanism.

FIG. 5 is an explanatory diagram of a differential pulley speed reduction mechanism.

FIG. 6 is an explanatory diagram of the operation of the differential pulley speed reduction mechanism of FIG. 1;

FIG. 7 is an explanatory diagram of a configuration of a speed reduction mechanism including a worm gear, a spur gear, and the like of a conventional paper feeding apparatus.

[Explanation of symbols]

 Reference Signs List 1 motor 2 motor pulley 3 motor timing belt 4 pulley 5 shaft 6, 6L differential pulley 7, 7R, 7L pulley (sixth pulley) 8, 8R, 8L timing belt 9, 9L differential pulley 10, 10R, 10L pulley (fifth pulley) 11, shaft 12 timing belt (belt member) 13, 13R, 13L pulley (ninth pulley) 14, 14R, 14L pulley (fourth pulley) 15, 15R, 15L pulley (first 2, 16R, 16L pulley (eighth pulley) 17, 17R, 17L pulley 18, 18R, 18L pulley 19, 19R, 19L pulley (seventh pulley) 20, 20R, 20L pulley (first pulley) Pulley) 21, 21R, 21L Pulley (third Ri) 22 List 23 timing belt 24,24R, 24L pulley 25,25R, 25L pulley 30 frames 34 form EC controller

Claims (1)

(57) [Claims] 1. A wrist on which an upper surface is substantially flat and paper is placed on the upper surface, a frame surrounding the wrist so that the wrist can move up and down, and each pulley operates in substantially the same plane; And a differential pulley deceleration mechanism for moving the paper up and down in the frame while supporting the paper from the side, and feeding the paper to the paper surface recording device. First and second pulleys movably provided; third and fourth pulleys rotatably provided at two horizontally separated portions below the frame; and the third and fourth pulleys below the frame. 5th and 6th pulleys provided between the 4 pulleys, and are horizontally separated from the wrist supporting side surface, and
And two locations located inside the location where the second pulley is provided and seventh and eighth locations located at the center location of the two locations.
And a ninth pulley, which is wound around the first pulley and travels downward to the seventh pulley, and travels through the seventh pulley toward the eighth pulley in one direction substantially along the wrist side surface. ,
Via the eighth pulley, upward toward the second pulley, wrapping around the second pulley, downward toward the fourth pulley, and via the fourth pulley to the wrist side surface Along the other direction along the sixth pulley, and the ninth upward through the sixth pulley.
Toward the fifth pulley, winding downward around the ninth pulley, toward the fifth pulley, passing through the fifth pulley in the other direction toward the third pulley, and moving toward the third pulley. A belt member heading upward through the first pulley and a peripheral speed difference driving means for driving the fifth and sixth pulleys so as to cause a difference in their respective peripheral speeds. A sheet feeder having a differential pulley speed reduction mechanism.