US20190263609A1

US20190263609A1 - Sheet Supplier

Info

Publication number: US20190263609A1
Application number: US16/282,457
Authority: US
Inventors: Yoichiro NISHIMURA; Gakuro KANAZAWA; Tetsuo Asada; Asami Hashimoto
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-02-23
Filing date: 2019-02-22
Publication date: 2019-08-29
Also published as: JP2019142706A

Abstract

A sheet supplier includes: a tray having a support surface; a roller that supplies a sheet supported on the support surface; an arm pivotable about a pivot shaft, extending in a supply direction and toward the support surface, and supports the roller at its pivotal distal end portion; a motor; and a driving-force transmitting mechanism supported by the arm and configured to transmit a driving force supplied from the motor, to the roller. The driving-force transmitting mechanism includes: a rotating member supported by the pivot shaft and configured to be rotated by the driving force supplied from the motor; and a speed changer configured to determine a rotational speed of the roller to a speed different from a rotational speed of the rotating member.

Description

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent Application No. 2018-031121, which was filed on Feb. 23, 2018, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND

The following disclosure relates to a sheet supplier configured to supply a sheet.
There are known sheet suppliers including a roller that is rotated to supply the uppermost one of sheets stacked and supported on a tray, so as to supply the uppermost sheet in a supply direction. In one example of the sheet suppliers, the roller is supported at a distal end of a pivotable arm. A pivot shaft is disposed at a basal end of the arm above its distal end. The arm extends so as to be lower at its downstream portion than at its upstream portion in the supply direction. Pivotal movement of the arm enables the roller to come into contact with the sheet regardless of the number of sheets supported on the tray.

SUMMARY

The angle of the arm with respect to the sheet changes depending upon the number of sheets stacked on the tray. The angle is small in the case where a large number of sheets are stacked on the tray. When the angle is small, a force by which the roller pushes the sheet downward (normal load) is small. This state increases the possibility of occurrence of no-sheet feeding in which no sheet is supplied in a state in which the roller is rotated. In contrast, the angle is large in the case where a small number of sheets are stacked on the tray. When the angle is large, the normal load is large. This state increases the possibility of occurrence of double feeding of sheets.
To prevent the above-described no-sheet feeding and double feeding, the arm is, for example, required to be made longer to reduce changes in angle of the arm with respect to the sheet due to changes in the number of sheets stacked on the tray. The longer arm however increases the size of the sheet supplier.
Accordingly, an aspect of the disclosure relates to a sheet supplier capable of reducing the possibility of occurrence of double feeding and no-sheet feeding of sheets supported on a tray without changing the length of an arm.
In one aspect of the disclosure, a sheet supplier including: a tray having a support surface configured to support a plurality of sheets stacked on the support surface; a roller located above the support surface and configured to supply a sheet supported on the support surface, in a supply direction; an arm pivotable about a pivot shaft, the arm extending such that a portion of the arm nearer to the support surface than to the pivot shaft is located downstream, in the supply direction, of a portion of the arm nearer to the pivot shaft than to the support surface, the arm having a pivotal distal end portion supporting the roller such that the roller is rotatable; a motor; and a driving-force transmitting mechanism supported by the arm and configured to transmit a driving force supplied from the motor, to the roller. The driving-force transmitting mechanism includes: a rotating member supported by the pivot shaft and configured to be rotated by the driving force supplied from the motor; and a speed changer configured to determine a rotational speed of the roller to a speed different from a rotational speed of the rotating member, the rotational speed of the roller being the number of rotations of the roller rotated by the driving force transmitted from the rotating member for a unit time, the rotational speed of the rotating member being the number of rotations of the rotating member for the unit time.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, advantages, and technical and industrial significance of the present disclosure will be better understood by reading the following detailed description of the embodiment, when considered in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a multi-function peripheral 10;

FIG. 2 is an elevational view in vertical cross section schematically illustrating an internal structure of a printer 11;

FIG. 3 is a plan view of a supplier 16;

FIG. 4 is a plan view of a gear 27F of the supplier 16 and components around the gear 27F, illustrating a state in which the gear 27F is located at a first position;

FIG. 5 is an elevational view in vertical cross section, illustrating the supplier 16 and components near the supplier 16 in the printer 11;

FIG. 6 is a plan view of the gear 27F of the supplier 16 and the components around the gear 27F, illustrating a state in which the gear 27F is located at a second position;

FIG. 7 is an elevational view in vertical cross section, illustrating the supplier 16 and components near the supplier 16 in the printer 11; and

FIG. 8 is an elevational view in vertical cross section, schematically illustrating an internal structure of a printer 11 including two supply trays 20.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, there will be described one embodiment by reference to the drawings. It is to be understood that the following embodiment is described only by way of example, and the disclosure may be otherwise embodied with various modifications without departing from the scope and spirit of the disclosure. A multi-function peripheral (MFP) 10 is normally used in a state illustrated in FIG. 1. In the following description, the up and down direction 7 is defined in this state. The front and rear direction 8 is defined by regarding a side of the MFP 10 on which an opening 13 is formed as a front side, and the right and left direction 9 is defined in a state in which the MFP 10 is seen from a front side thereof. In the present embodiment, the up and down direction 7 corresponds to the vertical direction, and the front and rear direction 8 and the right and left direction 9 correspond to the horizontal direction in the state illustrated in FIG. 1. The front and rear direction 8 and the right and left direction 9 are orthogonal to each other.

Overall Configuration of MFP 10

As illustrated in FIG. 1, the MFP 10 has a generally rectangular parallelepiped shape. The MFP 10 has various functions such as a facsimile function and a printing function. The MFP 10 includes a printer 11 at its lower portion. The printer 11 is an ink-jet printer configured to record an image on a sheet 12 (see FIG. 2). The printer 11 includes a housing 14.
As illustrated in FIG. 2, the printer 11 includes a recorder 24, a platen 42, an output tray 21, a conveying roller pair 59, an output roller pair 44, a guide 32, an outer guide member 18, an inner guide member 19, and a sheet supplier. The sheet supplier includes a supply tray 20 as one example of a tray, a supplier 16, a supply motor 102 as one example of a motor (see FIG. 3), and a transmission gear 104 (see FIG. 3). The recorder 24, the platen 42, the conveying roller pair 59, the output roller pair 44, the guide 32, the outer guide member 18, the inner guide member 19, the supplier 16, the supply motor 102, and the transmission gear 104 are disposed in the housing 14.

Supply Tray

20

As illustrated in FIG. 1, the opening 13 is formed in a front portion of the housing 14. The supply tray 20 is insertable into and removable from the opening 13 in the front and rear direction 8. The supply tray 20 is shaped like a box opening upward. As illustrated in FIG. 2, a bottom surface 22 (as one example of a support surface) of the supply tray 20 is capable of supporting stacked sheets 12 of various sizes.

Output Tray

21

As illustrated in FIG. 1, the output tray 21 is located above the supply tray 20. The output tray 21 supports the sheet 12 discharged after an image is recorded on the sheet 12 by the recorder 24.

Supplier

16

As illustrated in FIG. 2, the supplier 16 is provided above the bottom surface 22 of the supply tray 20. The supplier 16 includes supply rollers 25 (each as one example of a roller), a supply arm 26 (as one example of an arm), and a driving-force transmitting mechanism 27.
The supply rollers 25 are rotatably supported by a shaft at a distal end portion 26A (as one example of a pivotal distal end portion) of the supply arm 26.
The supply arm 26 is pivotable in a first direction 98 and a second direction 99 about a pivot shaft 28 provided at a basal end portion 26B of the supply arm 26.
The first direction 98 coincides with the counterclockwise direction in FIG. 2. The first direction 98 is a direction in which the supply rollers 25 are moved downward. In other words, the first direction 98 is a direction in which the supply rollers 25 are moved toward the bottom surface 22.
The second direction 99 is reverse to the first direction 98. That is, the second direction 99 coincides with the clockwise direction in FIG. 2. The second direction 99 is a direction in which the supply rollers 25 are moved upward. In other words, the second direction 99 is a direction in which the supply rollers 25 are moved away from the bottom surface 22.
The supply arm 26 is urged in the first direction 98 by its own weight or an urging member such as a spring. This configuration enables the supply rollers 25 to move toward and away from the bottom surface 22 of the supply tray 20 or the sheet or sheets 12 supported on the bottom surface 22.
The supply arm 26 extends in a supply direction 100 which will be described below as the supply arm 26 extends from the pivot shaft 28 toward the bottom surface 22. In other words, the supply arm 26 is inclined so as to be lower at its rear portion than at its front portion.
A driving force generated by the supply motor 102 (see FIG. 3) is transmitted to the supply rollers 25 through the driving-force transmitting mechanism 27. When the supply rollers 25 are rotated in the second direction 99 in a state in which the supply rollers 25 are in contact with the uppermost one of the sheets 12 supported on the bottom surface 22 of the supply tray 20, the supply rollers 25 supply the sheet 12 in the supply direction 100 toward a conveyance path 65. In the present embodiment, the supply direction 100 coincides with the rear direction. It is noted that the driving-force transmitting mechanism 27 will be described later in detail.

Guide

32

As illustrated in FIG. 2, the guide 32 is disposed in the housing 14. The guide 32 is located at a rear of the supply tray 20 inserted in the housing 14, in other words, the guide 32 is located downstream of the supply tray 20 inserted in the housing 14, in the supply direction 100. The guide 32 has a guide surface 32A. The sheet 12 supplied by the supply rollers 25 in the supply direction 100 comes into contact with the guide surface 32A. The guide surface 32A is inclined with respect to the front and rear direction 8 so as to be higher at its rear portion than at its front portion.
A separating piece 33 is provided at a central portion of the guide surface 32A in the right and left direction 9 that coincides with a direction orthogonal to the surface of the sheet of FIG. 2. The separating piece 33 extends along the guide surface 32A and has a plurality of teeth arranged in a direction orthogonal to the right and left direction 9. A leading end or ends of the sheet or sheets 12 supplied by the supply rollers 25 in the supply direction 100 come into contact with the teeth. In the case where the leading ends of the sheets 12 come into contact with the teeth, the uppermost one of the sheets 12 which is in contact with the supply rollers 25 is separated by the separating piece 33 from the other sheets 12. As a result, only the uppermost sheet 12 is supplied to the conveyance path 65.

Conveyance Path

65

As illustrated in FIG. 2, the conveyance path 65 first extends from a rear end portion of the supply tray 20 so as to make an upward U-turn and then extends frontward substantially straight to the output tray 21. The conveyance path 65 is divided into a curved path 65A extending so as to make a U-turn, and a straight path 65B.
The curved path 65A is located downstream of the guide 32 in the supply direction 100. The curved path 65A is defined by the outer guide member 18 and the inner guide member 19 that are opposed to each other with a space therebetween so as to allow the sheet 12 to pass through the space. The straight path 65B is defined by the recorder 24 and the platen 42 that are opposed to each other with a space therebetween so as to allow the sheet 12 to pass through the space.
The sheet 12 supplied to the conveyance path 65 by the supply rollers 25 through the curved path 65A and the straight path 65B in a conveying direction 15 indicated by the one-dot chain line in FIG. 2.

Conveying Roller Pair 59 and Output Roller Pair 44

As illustrated in FIG. 2, the conveying roller pair 59 is disposed in the straight path 65B of the conveyance path 65. The conveying roller pair 59 includes a conveying roller 60 and a pinch roller 61. The output roller pair 44 is disposed in the straight path 65B of the conveyance path 65 at a position located downstream of the conveying roller pair 59 in the conveying direction 15. The output roller pair 44 includes an output roller 62 and a spur 63.
The conveying roller 60, the pinch roller 61, the output roller 62, and the spur 63 are rotated about the axis extending in the right and left direction 9.
The conveying roller 60 and the pinch roller 61 are in contact with each other. The output roller 62 and the spur 63 are in contact with each other. The conveying roller 60 and the output roller 62 are rotated by a driving force transmitted from a conveying motor, not illustrated. The sheet 12 is conveyed by the conveying roller pair 59 and the output roller pair 44 in the conveying direction 15 in a state in which the sheet 12 is nipped between the conveying roller pair 59 and the output roller pair 44.

Platen

42

As illustrated in FIG. 2, the platen 42 is disposed in the conveyance path 65 at a position located between the conveying roller pair 59 and the output roller pair 44. The platen 42 is disposed at a position opposed to the recorder 24 in the up and down direction 7. The platen 42 supports a lower surface of the sheet 12 being conveyed along the conveyance path 65.

Recorder

24

As illustrated in FIG. 2, the recorder 24 is disposed in the conveyance path 65 at a position located between the conveying roller pair 59 and the output roller pair 44. The recorder 24 is disposed above the conveyance path 65 at a position opposed to the platen 42. The recorder 24 includes a carriage 40 and a recording head 38.
The carriage 40 is disposed in an upper portion of the conveyance path 65 at a position opposed to the platen 42. The carriage 40 is reciprocated in a scanning direction (i.e., the right and left direction 9) orthogonal to the conveying direction 15.
The carriage 40 is supported by guide rails 56, 57 arranged in the front and rear direction 8 with a space therebetween. A well-known belt mechanism, not illustrated, is provided on at least one of the guide rails 56, 57. The carriage 40 is coupled to the belt mechanism. A driving force is transmitted to the carriage 40 from a carriage drive motor, not illustrated, via the belt mechanism. This enables the carriage 40 to reciprocate in the right and left direction 9.
The recording head 38 is mounted on the carriage 40. A multiplicity of nozzles 39 are formed in a lower surface of the recording head 38 which faces the platen 42. Ink is supplied to an ink cartridge, not illustrated, to the recording head 38. The recording head 38 ejects fine droplets of the ink from the nozzles 39. While the carriage 40 is being reciprocated in the right and left direction 9, the ink droplets are ejected from the nozzles 39 toward the platen 42. As a result, the ink droplets land on the sheet 12 supported on the platen 42, so that an image is recorded on the sheet 12.

Driving-Force Transmitting Mechanism 27

There will be next described the driving-force transmitting mechanism 27. As illustrated in FIGS. 2 and 3, the driving-force transmitting mechanism 27 includes gears 27A, 27B, 27C, 27D, 27E, 27F engaged with each other. The gears 27A, 27B, 27C, 27D, 27E, 27F are one example of a speed changer. The gears 27A, 27B, 27C, 27D, 27E, 27F are rotatably supported by the supply arm 26.
In the present embodiment, the size of each tooth and the tooth-to-tooth pitch are the same among the gears 27A, 27B, 27C, 27D, 27E, 27F. The diameter is the same among the gears 27A, 27B, 27C, 27D.
The gear 27F of the driving-force transmitting mechanism 27 (as one example of a rotating member and a slide gear) is rotated by the driving force transmitted from the supply motor 102 via components such as gears and belts. The driving force transmitted to the gear 27F transmitted to the supply rollers 25 via the gears 27E, 27D, 27C, 27B, 27A. It is noted that the diameters of the respective gears of the driving-force transmitting mechanism 27 may or may not be the same as each other.
The gear 27A is rotated together with the supply rollers 25 about a shaft 25A of the supply rollers 25. The gear 27B is rotated about a shaft 27BA and engaged with the gear 27A. The gear 27C is rotated about a shaft 27CA and engaged with the gear 27B. The gear 27D is rotated about a shaft 27DA and engaged with the gear 27C.
The gear 27E is rotated about a shaft 27EA. The gear 27E is a double gear. The gear 27E includes a gear 78 and a gear 79 formed in one unit. The gear 79 is located to the left of the gear 78. The diameter of the gear 79 is greater than that of the gear 78. The gear 79 is engaged with the gear 27D.
The gear 27F is supported by the pivot shaft 28 of the supply arm 26 and rotated about the pivot shaft 28. The gear 27F is not rotated together with the pivot shaft 28. The gear 27F is a double gear. The gear 27F includes a gear 80 and a gear 81 formed in one unit. The gear 81 is located to the left of the gear 80. The diameter of the gear 80 is greater than that of the gear 81.
The gear 27F is slidable in the axial direction of the pivot shaft 28, i.e., the right and left direction 9. It is noted that FIG. 3 omits illustration of a construction for sliding the gear 27E This construction will be described later in detail with reference to FIG. 4.
The gear 27F is slidable between a first position indicated by the solid line in FIG. 3 and a second position indicated by the broken line in FIG. 3. The second position is located to the left to the first position.
When the gear 27F is located at the first position, the gear 80 is engaged with the gear 78 of the gear 27E. The diameter of the gear 78 is less than that of the gear 80. That is, the number of the teeth of the gear 78 is less than the number of the teeth of the gear 80. When the driving force is transmitted from the gear 80 to the gear 78, the rotational speed of the gear 78 is greater than that of the gear 80. That is, the rotational speed of the gear 27E is greater than that of the gear 27E The rotational speed is the number of rotations per unit time (per minute in the present embodiment).
When the gear 27F is located at the second position, the gear 81 is engaged with the gear 79 of the gear 27E. The diameter of the gear 79 is greater than that of the gear 81. That is, the number of the teeth of the gear 79 is greater than the number of the teeth of the gear 81. Thus, when the driving force is transmitted from the gear 81 to the gear 79, the rotational speed of the gear 79 is less than that of the gear 81. That is, the rotational speed of the gear 27E is less than that of the gear 27F.
The driving force transmitted from the gear 27F to the gear 27E is transmitted to the supply rollers 25 via the same driving-force transmitting path (the gear 79 of the gear 27E and the gears 27D, 27C, 27B, 27A) regardless of using transmission of the driving force from the gear 80 to the gear 78 or using transmission of the driving force from the gear 81 to the gear 79. As described above, the diameters of the gears 27A, 27B, 27C, 27D are the same. Thus, the rotational speed of each gear is neither accelerated nor decelerated in the transmission of the driving force via the gears 27A, 27B, 27C, 27D. In the present embodiment, while the rotational speed is slightly decelerated between the gear 79 of the gear 27E and the gear 27D, the degree of this deceleration is less than the degree of acceleration or deceleration between the gear 27F and the gear 27E.
That is, when the gear 27F is located at the first position, the rotational speed of the supply rollers 25 is greater than that of the gear 27F. The state of the gears 27A, 27B, 27C, 27D, 27E, 27F in this case is one example of a first state. The gears 78, 79, 27D, 27C, 27B, 27A that transmit the driving force from the gear 27F to the supply rollers 25 such that the rotational speed of the supply rollers 25 is greater than that of the gear 27F are one example of a first gear train.
When the gear 27F is located at the second position, the rotational speed of the supply rollers 25 is less than that of the gear 27F. The state of the gears 27A, 27B, 27C, 27D, 27E, 27F in this case is one example of a second state. The gears 79, 27D, 27C, 27B, 27A that transmit the driving force from the gear 27F to the supply rollers 25 such that the rotational speed of the supply rollers 25 is less than that of the gear 27F is one example of a second gear train.
In view of the above, the gears 27A, 27B, 27C, 27D, 27E, 27F are switchable selectively to one of the first state and the second state by sliding movement of the gear 27F.
There will be next described a construction for sliding movement of the gear 27F. As illustrated in FIG. 4, the driving-force transmitting mechanism 27 includes a coil spring 66, a protrusion 67, a protrusion 68, and a cam 69.
The coil spring 66 is disposed to the right of the gear 27F. The coil spring 66 is disposed so as to surround the pivot shaft 28. In other words, the pivot shaft 28 extends through the coil spring 66. A left end of the coil spring 66 is in contact with a right surface 80A of the gear 80 of the gear 27F. A right end of the coil spring 66 is in contact with the supply arm 26. The coil spring 66 urges the gear 27F leftward.
The protrusion 67 protrudes from an outer circumferential surface of the pivot shaft 28 in the radial direction of the pivot shaft 28. The protrusion 67 contacts the cam 69 to limit rotation of the cam 69. The protrusion 68 protrudes rightward toward the gear 81 of the gear 27F from the supply arm 26 located to the left of the gear 27F.
The cam 69 is disposed to the left of the gear 27F. The cam 69 is disposed so as to surround the pivot shaft 28. In other words, the pivot shaft 28 extends through the cam 69. This configuration makes the cam 69 rotatable about the pivot shaft 28.
A right surface 69A of the cam 69 is in contact with a left surface 81A of the gear 81 of the gear 27F which is urged leftward by the coil spring 66. The cam 69 has a recessed portion 70 recessed leftward from the right surface 69A. The protrusion 67 is located at the recessed portion 70. The length of the recessed portion 70 in the front and rear direction 8 is greater than that of the protrusion 67 in the front and rear direction 8. The length of the recessed portion 70 in the right and left direction 9 is greater than that of the protrusion 67 in the right and left direction 9.
The right surface 69A of the cam 69 is pushed leftward by the gear 27F urged leftward by the coil spring 66. As a result, a left surface of the cam 69 is in contact with the protrusion 68. The left surface of the cam 69 includes a first surface 69B, a second surface 69C, a third surface 69D, and a fourth surface 69E. The first surface 69B extends in a direction orthogonal to the right and left direction 9. The second surface 69C extends from the first surface 69B in the circumferential direction of the cam 69. The second surface 69C is inclined with respect to the first surface 69B such that a portion of the second surface 69C which is far from the first surface 69B is located to the left of a portion of the second surface 69C which is near the first surface 69B. The third surface 69D extends in the circumferential direction from one of opposite ends of the second surface 69C, which one is farther from the first surface 69B than the other. The third surface 69D is inclined with respect to the first surface 69B such that a portion of the third surface 69D which is far from the first surface 69B is located to the right of a portion of the third surface 69D which is near the first surface 69B. The fourth surface 69E extends in the circumferential direction from one of opposite ends of the third surface 69D, which one is farther from the second surface 69C than the other. The fourth surface 69E extends in the direction orthogonal to the right and left direction 9. The fourth surface 69E is located to the right of the first surface 69B.
There will be next described operations of the cam 69. As illustrated in FIG. 2, an imaginary plane 86 is directed toward the bottom surface 22 so as to extend through the pivot shaft 28 and a contact position 85 at which the supply rollers 25 contact the bottom surface 22 or the uppermost sheet 12 supported on the bottom surface 22. The gear 27F is located at the first position (see FIG. 4) when an angle θ of the imaginary plane 86 with respect to the bottom surface 22 is less than a particular angle θ3.
The particular angle θ3 is half the sum of a first angle θ1 and a second angle θ2 illustrated in FIG. 5 (θ3=(θ1+θ2)/2). As illustrated in FIG. 5, the first angle θ1 is an angle of the imaginary plane 86 with respect to the bottom surface 22 in a state in which the maximum number of the sheets 12 storable in the supply tray 20 are stored in the supply tray 20. The second angle θ2 is an angle of the imaginary plane 86 with respect to the bottom surface 22 in a state in which any of the sheets 12 is not supported on the bottom surface 22.
That is, the gear 27F is located at the first position in the state represented by “θ1<=θ<θ3” (see FIG. 4).
As illustrated in FIG. 5, as the number of the sheets 12 stored in the supply tray 20 decreases for printing, the position of the supply rollers 25 moves downward. That is, the supply arm 26 pivots in a direction indicated by the arrow 98. This movement increases the angle θ.
As the supply arm 26 pivots in the direction indicated by the arrow 98, the protrusion 68 illustrated in FIG. 4 is moved rearward to push the second surface 69C of the cam 69. By being pushed rearward by the protrusion 68, the cam 69 is to rotate about the pivot shaft 28 in the direction indicated by the arrow 98. However, the protrusion 67 protruding from the outer circumferential surface of the pivot shaft 28 contacts a surface 70A of the recessed portion 70 which defines a front end of the recessed portion 70, thereby limiting rotation of the cam 69. As a result, the protrusion 68 is moved rearward while sliding on the second surface 69C of the cam 69.
When the supply arm 26 has further pivoted in the direction indicated by the arrow 98 by further decrease in the number of the sheets 12 stored in the supply tray 20, the protrusion 68 passes through the second surface 69C and faces the third surface 69D in the right and left direction 9. The cam 69 is moved leftward by an urging force of the coil spring 66. In this movement, since a reaction force is applied from the protrusion 68 to the third surface 69D, the cam 69 is rotated about the pivot shaft 28 in a direction indicated by the arrow 99. That is, the cam 69 is moved leftward by the urging force of the coil spring 66 while rotating. The protrusion 68 is slid along the third surface 69D. As a result, the protrusion 68 passes through the third surface 69D and contacts the fourth surface 69E (see FIG. 6). When the cam 69 is moved leftward, the gear 27F is also moved leftward by the urging force of the coil spring 66. As a result, the gear 27F is moved from the first position (see FIG. 4) to the second position (see FIG. 6).
Thereafter, the state illustrated in FIG. 6 is kept until the supply tray 20 becomes empty of the sheets 12. The gear 27F is located at the second position in the state illustrated in FIG. 6.
Here, the angle θ is the particular angle θ3 when the state of the protrusion 68 is changed from a state in which the protrusion 68 is in contact with the second surface 69C to a state in which the protrusion 68 is in contact with the third surface 69D. That is, the gear 27F is located at the second position in the state represented by “θ3<θ<=θ2”. That is, the gear 27F is located at the second position in the state in which the angle θ is greater than the particular angle θ3.
In view of the above, the gear 27F is located at the first position in the state represented by “θ1<=θ<θ3” (see FIG. 4), and the gear 27F is located at the second position in the state represented “θ3<θ<=θ2” (see FIG. 6).

Input Torque Required to Generate Conveying Force of One Newton

There will be next described, with reference to FIG. 7, a range of input torque required to generate a conveying force of one newton (N) in the present embodiment.
A normal (vertical) reaction force N is a reaction force of normal (vertical) load which is a force by which the bottom surface 22 or the uppermost sheet 12 supported on the bottom surface 22 is pushed downward by the supply rollers 25. The normal reaction force N is, for example, represented by the following Expression 1: N=T_N+F_N+W_N.
In Expression 1, T_Ndenotes a component of a normal reaction force generated by input torque T. F_Ndenotes a component of a normal reaction force generated by a seizing force F. W_Ndenotes a component of a normal reaction force generated by an urging force W. The input torque T is torque when the gear 27F is rotated by the driving force generated by the supply motor 102 and transmitted to the gear 27F from components outside the driving-force transmitting mechanism 27. The seizing force F is a force by which the supply rollers 25 supply the sheet 12 supported on the bottom surface 22. The urging force W is a force by which the supply arm 26 pushes the sheet 12 by its own weight or the urging member such as the spring.
T_Nis, for example, represented by the following expression: T_N=k×f/(L×cos θ). In this expression, k represents input torque required to generate the conveying force of 1 N (newton) and is, for example, represented by the following expression: k=r/i. Here, r denotes the radius of each of the supply rollers 25, and i denotes a speed reduction ratio, i.e., the number of rotations of the gear 27F with respect to one rotation of the supply rollers 25. In the above-described expression, f denotes a force by which the supply rollers 25 supply the sheet 12, L denotes the length of the supply arm 26 (specifically, the length of the supply arm 26, along the direction in which the supply arm 26 extends, between the pivot shaft 28 and the contact position 85 at which the supply rollers 25 contacts the bottom surface 22), and θ is an angle of the imaginary plane 86 with respect to the bottom surface 22. According to Expression 1 and the above-described expression for T_N, k is represented by the following Expression 2: k=(N−F_N−W_N)×L×cos θ/f.
In the present embodiment, the range of the normal reaction force N is set as described below, whereby the range of k is set. That is, k is set to a value in a state in which the normal reaction force N falls within the range which will be described below.
There will be next described the range of the normal reaction force N with reference to FIG. 7. When the supply rollers 25 supply one of the sheets 12 stacked and supported on the bottom surface 22 of the supply tray 20, a force by which the supply rollers 25 supply the sheet 12 needs to be less than a static frictional force of the supply rollers 25 against the sheet 12 in order to prevent slipping of the supply rollers 25. That is, a relationship “f<μ_rN” needs to be satisfied. In this relationship, f denotes a force by which the supply rollers 25 supply the uppermost one of the stacked sheets 12 (which contacts the supply rollers 25), μ_rdenotes a static friction coefficient of the supply rollers 25 against the sheet 12, and N denotes a normal reaction force. That is, in order to prevent slipping of the supply rollers 25, the normal reaction force N needs to satisfy a relationship represented by the following Expression 3: N>f/μ_r.
In order to prevent double feeding of the uppermost sheet 12 and the second sheet 12 of the stacked sheets 12 from the top when the supply rollers 25 supply one of the sheets 12 stacked and supported on the bottom surface 22 of the supply tray 20, a force required to supply the second sheet 12 with the uppermost sheet 12 needs to be less than frictional resistance against the second sheet 12. That is, a relationship represented by “μ_p1N<μ_p2N+R” needs to be satisfied. In this relationship, μ_p1denotes a coefficient of friction of the uppermost sheet 12 against the second sheet 12, μ_p2denotes a coefficient of friction of the second sheet 12 against the third sheet 12 of the stacked sheets 12 from the top, and R denotes separating resistance acting on the second sheet 12 when the separating piece 33 separates the second sheet 12 from the top.
Here, focusing on the uppermost sheet 12, the separating resistance R may be represented by the following expression: R=f−μ_p1N. According to the above-described two expressions (“μ_p1N<μ_p2N+R” and “R=f−μ_p1N”), the normal reaction force N needs to satisfy a relationship represented by the following Expression 4 in order to prevent double feeding of the second sheet 12: N<f/(2μ_p1−μ_p2).
In view of the above, k is set to a value in the state in which the normal reaction force N falls within the range satisfying Expressions 3 and 4. In the present embodiment, specifically, when the gear 27F is located at the first position, k is set to a value greater than or equal to eleven, and when the gear 27F is located at the second position, k is set to a value less than or equal to four. It should be understood that k may be set to any value other than the above-described values.
There will be next described changes of normal load due to acceleration and deceleration of the rotational speed of the supply rollers 25 with respect to the rotational speed of the gear 27E As described above, the normal reaction force N that is a reaction force of normal load which is a force by which the bottom surface 22 or the uppermost sheet 12 supported on the bottom surface 22 is pushed downward by the supply rollers 25 is represented by the above-described Expression 1.
As described above, T_Nis represented by “T_N=k×f/(L×cos θ). Expression 1 and the expression relating to T_Nindicate that the normal load changes with increase and decrease in the value of k. As described above, k is represented by “k=r/i” (noted that r represents the radius of each of the supply rollers 25, and i represents the speed reduction ratio). Thus, the normal load decreases with increase in the speed reduction ratio i and increases with decrease in the speed reduction ratio i. Here, the speed reduction ratio i decreases when the speed of the supply rollers 25 increases with respect to the speed of the gear 27F, and the speed reduction ratio i increases when the speed of the supply rollers 25 decreases with respect to the speed of the gear 27E In other words, the normal load increases when the speed of the supply rollers 25 increases with respect to the speed of the gear 27F, and the normal load decreases when the speed of the supply rollers 25 decreases with respect to the speed of the gear 27E

Transmission Gear

104

As illustrated in FIG. 3, the driving force generated by the supply motor 102 is transmitted to the transmission gear 104. The transmission gear 104 transmits, to the gear 27F, the driving force transmitted from the supply motor 102.
The transmission gear 104 is supported by a frame of the printer 11, not illustrated, so as to be rotatable about a shaft 104A. The transmission gear 104 is a double gear. The transmission gear 104 includes a gear 105 (as one example of a third gear) and a gear 106 (as one example of a fourth gear) formed in one unit. The gear 106 is located to the left of the gear 105. The diameter of the gear 106 is greater than that of the gear 105.
When the gear 27F is located at the first position, the gear 27F is located at a position indicated by the solid line in FIG. 3. In this state, the gear 105 is engaged with the gear 80 of the gear 27F, and the gear 106 is separated from the gear 81 of the gear 27E The diameter of the gear 105 is less than that of the gear 80. That is, the number of the teeth of the gear 105 is less than the number of the teeth of the gear 80. When the driving force is transmitted from the gear 105 to the gear 80, the rotational speed of the gear 80 is less than that of the gear 105. That is, the rotational speed of the gear 27F located at the first position is less than that of the transmission gear 104.
As described above, when the gear 27F is located at the first position, the driving force is transmitted from the gear 80 to the gear 78 of the gear 27E. In this transmission, the rotational speed of the gear 78 is greater than that of the gear 80. Here, the diameter of the gear 105 is equal to that of the gear 78. Thus, the gear ratio of the gear 80 to the gear 105 is equal to the gear ratio of the gear 80 to the gear 78. As a result, the degree of deceleration of the rotational speed in the transmission of the driving force from the gear 105 to the gear 80 is equal to the degree of acceleration of the rotational speed in the transmission of the driving force from the gear 80 to the gear 78. Thus, the rotational speed of the gear 78 is equal to that of the gear 105. That is, when the gear 27F is located at the first position, the rotational speed of the gear 27E is equal to that of the transmission gear 104.
When the gear 27F is located at the second position, the gear 27F is located at a position indicated by the broken line in FIG. 3. In this state, the gear 106 is engaged with the gear 81 of the gear 27F, and the gear 105 is separated from the gear 80 of the gear 27F. The diameter of the gear 106 is greater than that of the gear 81. That is, the number of the teeth of the gear 106 is greater than the number of the teeth of the gear 81. Thus, when the driving force is transmitted from the gear 106 to the gear 81, the rotational speed of the gear 81 is greater than that of the gear 106. That is, the rotational speed of the gear 27F located at the second position is greater than that of the transmission gear 104. In view of the above, the rotational speed of the gear 27F located at the second position is greater than that of the gear 27F located at the first position.
As described above, when the gear 27F is located at the second position, the driving force is transmitted from the gear 81 to the gear 79 of the gear 27E. In this transmission, the rotational speed of the gear 79 is less than that of the gear 81. Here, the diameter of the gear 106 is equal to that of the gear 79. Thus, the gear ratio of the gear 81 to the gear 106 is equal to the gear ratio of the gear 81 to the gear 79. As a result, the degree of acceleration of the rotational speed in the transmission of the driving force from the gear 106 to the gear 81 is equal to the degree of deceleration of the rotational speed in the transmission of the driving force from the gear 81 to the gear 79. Thus, the rotational speed of the gear 79 is equal to that of the gear 106. That is, when the gear 27F is located at the second position, the rotational speed of the gear 27E is equal to that of the transmission gear 104.
In view of the above, the rotational speed of the gear 27E is equal to that of the transmission gear 104 regardless of the position of the gear 27E As described above, the driving force is transmitted from the gear 27F to the supply rollers 25 via the common driving-force transmitting path (the gear 79 of the gear 27E and the gears 27D, 27C, 27B, 27A). Thus, the rotational speed of the supply rollers 25 is kept constant regardless of the position of the gear 27F.

Effects

The inventors of the present application have found that a force by which the supply rollers 25 push the bottom surface 22 or the uppermost sheet 12 supported on the bottom surface 22 downward (normal load) is increased and reduced by changing the rotational speed of, e.g., the gears for transmitting the driving force to the supply rollers 25 in the supply arm 26. Specifically, in the case where the rotational speed of the supply rollers 25 is increased with respect to the rotational speed of the gear 27F, the normal load is increased, and in the case where the rotational speed of the supply rollers 25 is reduced with respect to the rotational speed of the gear 27F, the normal load is reduced. Thus, in the present embodiment, the speed changer (the gears 27A, 27B, 27C, 27D, 27E, 27F) can change the rotational speed of the supply rollers 25 with respect to the rotational speed of the gear 27F to adjust the normal load.
The inventors of the present application have also found that, in the case where the relationship represented by Expression 3 is satisfied, no-sheet feeding of the sheet 12 does not occur due to slipping of the supply rollers 25 on the sheet 12. The inventors of the present application have also found that, in the case where the relationship represented by Expression 4 is satisfied, double feeding of the sheets 12 is prevented. In the present embodiment, the ratio of the rotational speed of the supply rollers 25 to the rotational speed of the gear 27F is set to a value that satisfies Expression 3. Thus, providing the speed changer prevents no-sheet feeding of the sheet 12 which is caused due to excessively small normal load. In the present embodiment, the ratio of the rotational speed of the supply rollers 25 to the rotational speed of the gear 27F is set to a value that satisfies Expression 4. Thus, providing the speed changer prevents no-sheet feeding of the sheet 12 which is caused due to excessively heavy normal load.
In the present embodiment, the state of the speed changer is switched to meet the needs both in the case where the normal load needs to be increased and in the case where the normal load needs to be reduced.
In the present embodiment, the gear 27F is slid to the first position to increase the rotational speed of the supply rollers 25. That is, the gear 27F is slid to the first position to establish the first state of the speed changer. The gear 27F is slid to the second position to reduce the rotational speed of the supply rollers 25. That is, the gear 27F is slid to the second position to establish the second state of the speed changer.
In the present embodiment, when the gear 27F is located at the first position, k is set to a value greater than or equal to eleven. Thus, when compared with the case where k is set to a value less than eleven, it is possible to greatly increase the normal load to reduce the possibility of occurrence of misfeeding.
In the present embodiment, when the gear 27F is located at the second position, k is set to a value less than or equal to four. Thus, when compared with the case where k is set to a value greater than four, it is possible to greatly reduce the normal load to reduce the possibility of occurrence of double feeding.
Increase in the number of the sheets 12 supported on the supply tray 20 decreases the angle θ of the imaginary plane 86 with respect to the bottom surface 22 and thereby decreases the normal load. In the present embodiment, when the angle θ of the imaginary plane 86 with respect to the bottom surface 22 is small, the gear 27F is located at the first position, and thus the speed changer is in the first state. When the speed changer is in the first state, the rotational speed of the supply rollers 25 is increased to increase the normal load. That is, it is possible to prevent reduction in the normal load which is caused by reduction in the angle θ of the imaginary plane 86 with respect to the bottom surface 22.
Decrease in the number of the sheets 12 supported on the supply tray 20 increases the angle θ of the imaginary plane 86 with respect to the bottom surface 22 and thereby increases the normal load. In the present embodiment, when the angle θ of the imaginary plane 86 with respect to the bottom surface 22 is large, the gear 27F is located at the second position, and thus the speed changer is in the second state. When the speed changer is in the second state, the rotational speed of the supply rollers 25 is reduced to reduce the normal load. That is, it is possible to prevent increase in the normal load which is caused by increase in the angle θ of the imaginary plane 86 with respect to the bottom surface 22.
In the present embodiment, the particular angle θ3 is half the sum of the first angle θ1 and the second angle θ2 illustrated in FIG. 4. That is, the state of the speed changer can be switched at the exactly middle of the state in which the normal load is the largest (i.e., the state in which any of the sheets 12 is not supported on the supply tray 20) and the state in which the normal load is the smallest (i.e., the state in which the maximum number of the sheets 12 storable in the supply tray 20 are stored in the supply tray 20).
In the present embodiment, increase in the speed of the gear 27E which is caused by transmission of the driving force from the gear 80 of the gear 27F to the gear 78 of the gear 27E is offset by reduction in the speed of the gear 27F which is caused by transmission of the driving force from the gear 105 of the transmission gear 104 to the gear 80 of the gear 27F. Furthermore, reduction in the speed of the gear 27E which is caused by transmission of the driving force from the gear 81 of the gear 27F to the gear 79 of the gear 27E is offset by increase in the speed of the gear 27F which is caused by transmission of the driving force from the gear 106 of the transmission gear 104 to the gear 81 of the gear 27F. As a result, the rotational speed of the supply rollers 25 can be kept constant regardless of changes of the rotational speed by the speed changer.

Modifications

The MFP 10 may include a plurality of supply trays 20. For example, as illustrated in FIG. 8, the MFP 10 may include two supply trays 20 (20A, 20B). In this configuration, the MFP 10 includes the suppliers 16 corresponding to the respective supply trays 20A, 20B. The supply tray 20B is located under the supply tray 20A. The two supply trays 20A, 20B have generally the same construction.
The length L1 of the supply arm 26 of the driving-force transmitting mechanism 27 in the supplier 16 corresponding to the supply tray 20A is different from the length L2 of the supply arm 26 of a driving-force transmitting mechanism 77 in the supplier 16 corresponding to the supply tray 20B.
It is noted that the definition of the length of the supply arm 26 is the same as that in the above-described embodiment, and the length of the supply arm 26 is a length between the pivot shaft 28 and the contact position 85 at which the supply rollers 25 contact the bottom surface 22, in the direction in which the supply arm 26 extends. The angle θ4 of the supply arm 26 corresponding to the supply tray 20A with respect to the bottom surface 22 is equal to the angle θ5 of the supply arm 26 corresponding to the supply tray 20B with respect to the bottom surface 22.
Input torque k1 required for the supply rollers 25 corresponding to the supply tray 20A to generate a conveying force of 1 N (newton) is different from input torque k2 required for the supply rollers 25 corresponding to the supply tray 20B to generate the conveying force of 1 N (newton).
In the configuration illustrated in FIG. 8, the ratio between k1 and the length L (k1/L1) is equal to the ratio between k2 and the length L2 (k2/L2).
The above-described Expression 1 representing the normal reaction force N can be rewritten as the following Expression 5: N=(k/(L×cos θ)+tan θ)×f+W_N.
Here, the urging force W_Nand the force f by which the supply rollers 25 supply the sheet 12 are determined regardless of the length L of the supply arm 26. Thus, in the case where the angles θ of the respective suppliers 16 are the same as each other, when the ratios for the respective suppliers 16 each between the input torque k required for the supply rollers 25 to generate the conveying force of 1 N (newton) and the length L of the supply arm 26 (k/L) are made equal to each other, the normal reaction forces N for the respective suppliers 16 can be made the same as each other.
In the configuration illustrated in FIG. 8, in the case where the angle θ4 and the angle θ5 are equal to each other, the ratio of k1 to the length L1 (k1/L1) and the ratio of k2 to the length L2 (k2/L2) are equal to each other. Thus, the amount of the normal reaction force N acting on the supply rollers 25 for the supply tray 20A and that of the normal reaction force N acting on the supply rollers 25 for the supply tray 20B are equal to each other. Accordingly, in the case where the MFP 10 includes a plurality of the supply trays 20, it is possible to reduce variations in force by which the sheet 12 is supplied among the supply trays 20.
In the above-described embodiment, the driving force is transmitted from the gear 27F to the supply rollers 25 via the common gears (the gears 27E, 27D, 27C, 27B, 27A) regardless of the position of the gear 27F. However, the gears for transmitting the driving force from the gear 27F to the supply rollers 25 when the gear 27F is located at the first position and the gears for transmitting the driving force from the gear 27F to the supply rollers 25 when the gear 27F is located at the second position may be different from each other. That is, the driving-force transmitting path from the gear 27F to the supply rollers 25 may be different between or among the positions of the gear 27F.
In the above-described embodiment, as illustrated in FIG. 3, the gear 27F is a slidable double gear, and the gear 27E is a double gear. However, the configuration of the driving-force transmitting mechanism 27 is not limited to that illustrated in FIG. 3 and may be any of well-known configurations. For example, belts for transmission of the driving force may be disposed instead of some gears. For example, the printer 11 may be configured such that the gear 27C is a slidable double gear, and the gear 27B is a double gear. That is, any of the gears other than the gear 27F supported by the pivot shaft 28 may be a slidable gear.
In the above-described embodiment, the particular angle θ3 serving as a boundary between the first position and the second position of the gear 27F is half the sum of the first angle θ1 and the second angle θ2 illustrated in FIG. 4. However, the particular angle θ3 is not limited to the half angle. For example, the particular angle θ3 may be an angle closer to the first angle θ1 than the half angle.
In the above-described embodiment, the transmission gear 104 is engaged with the gear 27E However, the transmission gear 104 may not be engaged with the gear 27F as long as the transmission gear 104 is capable of increasing and reducing the rotational speed of the gear 27E For example, another or other gears may be disposed between the transmission gear 104 and the gear 27F.
The diameter of the gear 105 of the transmission gear 104 and the diameter of the gear 78 of the gear 27E are equal to each other in the above-described embodiment but may be different from each other. The diameter of the gear 106 of the transmission gear 104 and that of the gear 79 of the gear 27E are equal to each other in the above-described embodiment but may be different from each other.
The sheet supplier may not include the transmission gear 104.
In the above-described embodiment, the gears 27A, 27B, 27C, 27D, 27E, 27F of the driving-force transmitting mechanism 27 as one example of the speed changer are switchable between the first state and the second state by sliding movement of the gear 27F.
However, a means for switching the speed changer between the first state and the second state is not limited to sliding movement of the gear 27F and may be any of various well-known means. For example, the driving-force transmitting mechanism 27 may include a planetary gear. Revolving of this planetary gear may switch the driving-force transmitting path in the driving-force transmitting mechanism 27 to switch the speed changer between the first state and the second state.
While the gear 27F is slid by the configuration illustrated in FIG. 4 in the above-described embodiment, the configuration for sliding the gear 27F is not limited to the configuration illustrated in FIG. 4. For example, the gear 27F may be slid by a driving force transmitted from a drive source such as a solenoid at a predetermined timing.
The speed changer may not be switched between the first state and the second state. For example, the speed changer may be configured such that the rotational speed of the supply rollers 25 is always greater than that of the gear 27F, that is, the speed changer may be configured such that the speed changer is always in the first state. For example, the speed changer may be configured such that the rotational speed of the supply rollers 25 is always less than that of the gear 27F, that is, the speed changer may be configured such that the speed changer is always in the second state.
In the above-described embodiment, the size of each tooth and the tooth-to-tooth pitch are the same among the gears 27A, 27B, 27C, 27D, 27E, 27F but may be different among the gears 27A, 27B, 27C, 27D, 27E, 27F. In the above-described embodiment, since the size of each tooth and the tooth-to-tooth pitch are the same among these gears, the rotational speed of each gear is increased and reduced by the diameter of each gear. However, in the case where the size of each tooth and the tooth-to-tooth pitch are different among the gears, the rotational speed of each gear may be increased and reduced by the size of each tooth and the tooth-to-tooth pitch of each gear.
The number of the gears of the driving-force transmitting mechanism 27 is not limited to six. For example, the number of the gears of the driving-force transmitting mechanism 27 may be five.
The sheet supplier is provided in the printer 11 in the above-described embodiment but may be provided in any device other than the printer 11 such as a scanner.

Claims

What is claimed is:

1. A sheet supplier, comprising:

a tray comprising a support surface configured to support a plurality of sheets stacked on the support surface;

a roller located above the support surface and configured to supply a sheet supported on the support surface, in a supply direction;

an arm pivotable about a pivot shaft, the arm extending such that a portion of the arm nearer to the support surface than to the pivot shaft is located downstream, in the supply direction, of a portion of the arm nearer to the pivot shaft than to the support surface, the arm comprising a pivotal distal end portion supporting the roller such that the roller is rotatable;

a motor; and

a driving-force transmitting mechanism supported by the arm and configured to transmit a driving force supplied from the motor, to the roller,

wherein the driving-force transmitting mechanism comprises:

a rotating member supported by the pivot shaft and configured to be rotated by the driving force supplied from the motor; and

a speed changer configured to determine a rotational speed of the roller to a speed different from a rotational speed of the rotating member, the rotational speed of the roller being the number of rotations of the roller rotated by the driving force transmitted from the rotating member for a unit time, the rotational speed of the rotating member being the number of rotations of the rotating member for the unit time.

2. The sheet supplier according to claim 1,

wherein a normal reaction force N (in newton) is a reaction force against a force by which the roller being rotated at the rotational speed determined by the speed changer and different from the rotational speed of the rotating member pushes one of the support surface and the sheet supported by the support surface, and

wherein a value obtained by dividing a roller radius of the roller by a speed reduction ratio of the roller to the rotating member is set to a value within a range in which the normal reaction force N satisfies the following Expression 1 and Expression 2: N>f/μ_rand N<f/(2μ_p1−μ_p2), where

f is a force by which the roller supplies the sheet in the supply direction;

μ_ris a static friction coefficient of the roller against an uppermost one of the plurality of sheets supported by the support surface;

μ_p1is a dynamic friction coefficient of the uppermost one of the plurality of sheets against a second one of the plurality of sheets supported by the support surface from a top of the plurality of sheets; and

μ_p2is a dynamic friction coefficient of the second one of the plurality of sheets against a third one of the plurality of sheets supported by the support surface from the top of the plurality of sheets.

3. The sheet supplier according to claim 1, wherein, in a case where the speed changer is in a first state in which the rotational speed of the roller is greater than the rotational speed of the rotating member, a value obtained by dividing a roller radius of the roller by a speed reduction ratio of the roller to the rotating member is set to a value greater than or equal to eleven.

4. The sheet supplier according to claim 1, wherein, in a case where the speed changer is in a second state in which the rotational speed of the roller is less than the rotational speed of the rotating member, a value obtained by dividing a roller radius of the roller by a speed reduction ratio of the roller to the rotating member is set to a value less than or equal to four.

5. The sheet supplier according to claim 1, wherein a state of the speed changer is switchable between a first state in which the rotational speed of the roller is greater than the rotational speed of the rotating member and a second state in which the rotational speed of the roller is less than the rotational speed of the rotating member.

6. The sheet supplier according to claim 5, wherein the speed changer comprises:

a slide gear slidable to a first position and a second position along an axial direction of the pivot shaft;

a first gear train engaged with the slide gear located at the first position to transmit a driving force transmitted from the slide gear, to the roller such that the rotational speed of the roller becomes greater than a rotational speed of the slide gear; and

a second gear train engaged with the slide gear located at the second position to transmit the driving force transmitted from the slide gear, to the roller such that the rotational speed of the roller becomes less than the rotational speed of the slide gear.

7. The sheet supplier according to claim 6, wherein the slide gear is the rotating member.

8. The sheet supplier according to claim 6,

wherein the slide gear is located at the first position when an angle of an imaginary plane with respect to the support surface is less than a particular angle, and the imaginary plane is directed toward the support surface and extends through the pivot shaft and a contact position at which the roller contacts one of the support surface and the sheet supported by the support surface, and

wherein the slide gear is located at the second position when the angle of the imaginary plane with respect to the support surface is greater than the particular angle.

9. The sheet supplier according to claim 8, wherein the particular angle is half a sum of (i) a first angle that is an angle of the imaginary plane with respect to the support surface in a state in which a maximum number of sheets storable in the tray are stored in the tray and (ii) a second angle that is an angle of the imaginary plane with respect to the support surface in a state in which no sheet is supported by the tray.

10. The sheet supplier according to claim 6, further comprising:

a third gear engaged with the slide gear located at the first position to transmit the driving force supplied from the motor, to the slide gear; and

a fourth gear engaged with the slide gear located at the second position to transmit the driving force supplied from the motor, to the slide gear,

wherein the rotational speed of the slide gear being rotated when the slide gear is located at the first position and engaged with the third gear is less than the rotational speed of the slide gear being rotated when the slide gear is located at the second position and engaged with the fourth gear, and

wherein the rotational speed of the roller being rotated by the driving force transmitted from the slide gear by the first gear train when the slide gear is located at the first position is equal to the rotational speed of the roller being rotated by the driving force transmitted from the slide gear by the second gear train when the slide gear is located at the second position.

11. The sheet supplier according to claim 1, further comprising:

a plurality of trays each as the tray;

a plurality of rollers, each as the roller, provided respectively for the plurality of trays;

a plurality of arms, each as the arm, provided respectively for the plurality of trays; and

a plurality of driving-force transmitting mechanisms, each as the driving-force transmitting mechanism, provided respectively for the plurality of trays,

wherein a ratio between (i) a value obtained by dividing a roller radius of the roller by a speed reduction ratio of the roller to the rotating member and (ii) a length of the arm is identical among the plurality of arms, and

wherein the length of the arm is a length from a contact position at which the roller contacts the support surface, to the pivot shaft in a direction in which the arm extends.