TRANSPORTATION APPARATUS

Abstract

A transporting apparatus which is capable of restraining multi feed of transported media is provided. The transporting apparatus includes a first arm mounted on a supporting shaft so as to be pivotable with respect to the supporting shaft about a first pivotal portion, a second arm fixed with a feed roller and mounted on the first arm so as to be pivotable with respect to the first arm about the second pivotal portion, and a torsion coil spring acting on the second pivotal portion so as to urge the feed roller toward the sheet in a just-before-transport state and a sheet transporting state.

Description

BACKGROUND

1. Technical Field

The present invention relates to a transporting apparatus used for, for example, an ink jet printer.

2. Related Art

In the related art, a printer includes a transporting apparatus configured to separate a bundle of sheets (transported media) placed on a placing tray of the printer into pieces and feed individual sheets one by one therefrom. In order to ensure feeding of the sheets by a feed roller, such a transporting apparatus is configured to maintain the feed roller in a state of being in press-contact with the sheets by urging the feed roller toward the sheets (see JP-A-2003-285936).

Referring now to FIGS. 9A and 9B, a configuration of the transporting apparatus in the related art will be described.

A transporting apparatus 100 includes a placing tray 110 configured to place sheets Q, and a feed roller 120 configured to transport the sheets Q placed on the placing tray 110 toward a printing unit of the printer. The feed roller 120 is attached to a drive shaft 140 via an arm 130. The feed roller 120 is rotated by transmitting the rotation of the drive shaft 140 to the feed roller 120 via a gear train, not shown. A torsion coil spring 150 configured to urge the arm 130 toward the sheets Q, that is, counterclockwise, in the drawings is mounted on the transporting apparatus 100. Accordingly, the feed roller 120 is brought into press contact with the sheets Q. With the clockwise rotation of the feed roller 120 as shown by hollow arrows in the drawings, the sheets Q are fed in the direction of sheet transport indicated by arrows shown by alternate long and short chain lines.

In the transporting apparatus 100 described above, as the number of sheets Q decreases, the arm 130 and the feed roller 120 are allowed to pivot toward the placing tray 110 about the drive shaft 140 by being urged by the torsion coil spring 150. Accordingly, the feed roller 120 maintains its press contact position with respect to the sheet Q in a topmost position of a bundle of sheets according to the number of the sheets Q.

In such a transporting apparatus 100, the arm 130 is encouraged to pivot toward the sheets Q, that is, clockwise in the drawings by a frictional force f that the feed roller 120 receives from the sheets Q. Here, as shown in FIG. 9A, if the amount of loaded sheets Q is large, an acute angle formed by an axial line LR which connects the center of rotation of the drive shaft 140 and the center of rotation of the feed roller 120 and a placing surface 111 of the placing tray 110 (hereinafter, referred to as “acute angle X” becomes smaller. Accordingly, a component of a force which tries to pivot the arm 130 toward the sheets Q by the frictional force f (f·sinX) becomes smaller. In contrast, as shown in FIG. 9B, if the amount of loaded sheets Q is small, the above-described acute angle becomes larger than the acute angle X (hereinafter, referred to as “acute angle Y”). Accordingly, a component of a force which tries to pivot the arm 130 toward the sheets Q by the frictional force f (f·sinY) becomes larger than the same component with the acute angle X (f·sinX<f·sinY).

Therefore, if the amount of the loaded sheets Q is small, the feed roller 120 digs into the sheets Q and hence a frictional resistance between the feed roller 120 and the sheets Q becomes excessive. Consequently, an event such that the plurality of sheets Q are transported together at the time of transporting the sheet Q, so-called “multi feed” may occur.

SUMMARY

An advantage of some aspects of the invention is that a transporting apparatus which can restrain multi feed of transported media.

According to a first aspect of the invention, there is provided a transporting apparatus including: a transporting apparatus body configured to transport a transported medium by a feed roller; a first arm to be mounted on the transporting apparatus body so as to be pivotable about a first pivotal portion with respect to the transporting apparatus body; a second arm mounted on the first arm so as to be pivotable about a second pivotal portion with respect to the first arm and fixed with the feed roller at a position opposite from the first pivotal portion with respect to the second pivotal portion; and an urging member acting on the second pivotal portion so as to urge the feed roller toward the transported medium.

In this configuration, when the feed roller rotates, a component force of a frictional force that the feed roller receives from a transported medium is exerted on the second arm as a force to pivot toward the direction of rotation of the feed roller. With the action of this force, the second arm pivots in the direction of rotation of the feed roller about the axis of rotation of the feed roller, and the first arm pivots about the first pivotal portion, whereby the second pivotal portion moves toward the transported medium. Accordingly, an acute angle formed by an axial line connecting the center of rotation of the feed roller and the second pivotal portion and the transported medium decreases as the second pivotal portion moves.

Furthermore, with the movement of the second pivotal portion as described above, a force opposite from an urging force acts on the urging member. Then, the urging member exerts an urging force on the second pivotal portion by a restoration force of the urging member. Accordingly, the urging force increases so that the friction force that the feed roller receives from the transported medium and the force of the feed roller to transport the transported medium are balanced.

Accordingly, the urging force of the second urging member increases and the acute angle decreases in association with the movement of the second pivotal portion, so that the degree of increase in the frictional force which causes the feed roller to dig into the sheet becomes smaller than the degree of increase in the frictional force that the transported medium exerts on the feed roller. Consequently, the frictional force between the feed roller and the transported medium can be prevented from being excessive with respect to the frictional force between the two stacked transported media, whereby the multi feed of the transported media can be restrained.

It is preferable that a separating mechanism configured to separate a first transported medium in abutment with the feed roller from a second transported medium adjacent to the first transported medium in a stacking direction is provided, and the second arm moves toward a direction in which a rotational force of the feed roller acts on the first transported medium against an urging force of the urging member when a load for separating the first transported medium and the second transported medium exerted by the separating mechanism is large, whereby the urging force of the feed roller with respect to the first transported medium increases.

In this configuration, the urging force of the feed roller with respect to the first transported medium increases when the load for separating the first transported medium and the second transported medium is large, whereby the urging force is adjusted according to the load. In other words, when the load is relatively small, the first transported medium is transported in a state in which the amount of increase in the urging force is relatively decreased. In contrast, when the load is relatively large, the first transported medium is transported in a state in which the amount of increase in the urging force is relatively increased. Accordingly, since an urging force adequate for the load can be exerted on the feed roller, such event that the first transported medium and the second transported medium are transported simultaneously, that is, so-called multi feed of the transported media can be restrained.

It is preferable that a first inter-axis distance between the first pivotal portion and a second pivotal portion is smaller than a second inter-axis distance between the second pivotal portion and the axis of rotation of the feed roller.

In this configuration, since the first inter-axis distance is smaller than the second inter-axis distance, the distance of the pivotal movement of the second pivotal portion is larger than that in the case where the first inter-axis distance is larger than the second inter-axis distance. Accordingly, a range of adjustment of the force that the urging member urges the feed roller toward the transported medium can be increased.

It is preferable that when a state in which the rotation of the feed roller is stopped is changed to a state in which the rotational force of the feed roller is transmitted to the transported medium, the second pivotal portion pivots so that an acute angle formed by an axial line connecting the axis of rotation of the feed roller and the second pivotal portion and the transported medium becomes minimum.

In this configuration, the frictional force between the two stacked transported media becomes maximum when a state in which the rotation of the feed roller is stopped is changed to a state in which the rotational force of the feed roller is transmitted to the transported medium, whereby the force to cause the second arm to rotate toward the direction of rotation of the feed roller becomes maximum. With this force, the second pivotal portion pivots so that an acute angle formed by an axial line connecting an axis of rotation of the feed roller and a second pivotal shaft and the transported medium becomes minimum. In this case, an obtuse angle formed by the direction of the urging force exerted by the urging member on the feed roller toward the transported medium and the direction of transport of the transported medium is reduced in comparison with that in the state in which the rotation of the feed roller is stopped. Accordingly, increase in the frictional force that the feed roller receives from the transported medium caused by the urging force of the urging member can be restrained. Therefore, the feed roller can be prevented from digging into the transported medium.

It is preferable that the transporting apparatus is provided with a placing surface for placing the transported medium at a position opposing the feed roller, a cover configured to cover the first pivotal portion from the outside thereof in the direction of the radius of the pivotal movement of the first pivotal portion, and restrict the number of the transported media to be placed by a gap formed in cooperation with the placing surface is provided at a portion of the first pivotal portion opposing the transported medium, and the cover is provided over a range of the pivotal movement of the first arm in association with the action of the feed roller which transports the transported medium.

When the second pivotal portion is provided with a mechanism which restricts the number of transported media to be placed, the second pivotal portion pivots about the first pivotal portion in association with the pivotal movement of the first arm and the second arm under the condition in which the feed roller transports the transported media. Therefore, the position of the second pivotal portion with respect to the placing surface changes. Consequently, the position to restrict the number of transported media to be placed varies as well. Accordingly, the extent of allowable amount of the transported media to be placed thereon cannot be defined accurately.

In this regard, according to the embodiment of the invention, since the cover covers the first pivotal portion from the outside in the direction of the radius of the pivotal movement of the first pivotal portion, the position of cover with respect to the placing surface does not change even when the first pivotal portion is pivoted. Therefore, the positions of the placing surface and the cover do not change in the circumstance in which the feed roller transports the transported medium. Therefore, the number of the transported medium to be placed can be defined accurately.

Furthermore, since the cover is provided over the range of the pivotal movement of the first arm, the transported medium is restrained from deviating from the gap formed by the placing surface and the cover in the course of the pivotal movement of the first arm.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a schematic perspective view of a printer according to an embodiment.

FIG. 2 is a schematic perspective view of a transporting apparatus according to the embodiment.

FIG. 3 is an exploded perspective view of a pickup unit according to the embodiment.

FIG. 4 is a diagrammatic drawing showing a gear train of the pickup unit.

FIG. 5A is a side view of the transporting apparatus in a waiting state.

FIG. 5B is a diagrammatic drawing showing the transporting apparatus in FIG. 5A.

FIG. 6A is a side view showing the transporting apparatus just moments before the start of transport.

FIG. 6B is a diagrammatic drawing showing the transporting apparatus in FIG. 6A.

FIG. 7A is a side view showing the transporting apparatus in a state of transporting a sheet.

FIG. 7B is a diagrammatic drawing showing the transporting apparatus in FIG. 7A.

FIG. 8A is a side view showing the transporting apparatus just moments before the start of transport when using a thick sheet.

FIG. 8B is a diagrammatic drawing showing the transporting apparatus in FIG. 8A.

FIG. 9A is a diagrammatic drawing showing a transporting apparatus in the related art in a state in which a large number of sheets are loaded.

FIG. 9B is a diagrammatic drawing showing the transporting apparatus in the related art in a state in which a small number of sheets are loaded.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring now to FIGS. 1 to 8B, embodiments in which a transporting apparatus according to an aspect of the invention is embodied in an ink jet printer (hereinafter, referred to as “printer”) will be described. In the description given below, the expressions “fore-and-aft direction”, “up-and-down direction”, and “left-and-right direction” indicate directions “fore-and-aft direction”, “up-and-down direction”, and “left-and-right direction” indicated by arrows in FIG. 1 unless otherwise specified. In this embodiment, the vertical direction is defined as the same direction as the vertical direction.

As shown in FIG. 1, a printer 11 is a recording apparatus configured to record characters or images on sheets of paper (hereinafter, referred to simply as “sheet(s)”) as a recorded medium supplied from the rear side thereof. The printer 11 includes a transporting apparatus 12 as an Automatic Sheet Feeder (ASF) which feeds sheets, a recording apparatus 13 configured to record an image or the like on a sheet transported by the transporting apparatus 12, and a sheet discharging port 14 used for discharging the sheets on which the images or the like are recorded by the recording apparatus 13.

As shown in FIG. 2, the transporting apparatus 12 is provided with a placing tray 21 for placing the sheets thereon. The placing tray 21 includes an inclined placing surface 21a on which sheets P are placed and a supporting surface 21b which is a flat surface extending along the fore-and-aft direction and the left-and-right direction. A guide wall 22 fixed to the placing tray 21 and configured to perform positioning of the sheets is provided at a right end of the placing tray 21. A supporting shaft 23 as a transporting apparatus body, which extends leftward from the guide wall 22 and is connected to an electric motor, not shown, via a gear train is mounted on the guide wall 22. The supporting shaft 23 supports a pickup unit 24, which transports the sheets P toward the recording apparatus 13 (see FIG. 1).

The placing surface 21a is provided with a roller 25 (see FIGS. 5A and 5B) which comes into abutment with a sheet which is in abutment with the placing surface 21a. The supporting surface 21b is provided with a separation pad 26 as a separating mechanism for separating the sheets into pieces. The separation pad 26 includes a rectangular box-shaped case 26a to be mounted on the supporting surface 21b, and a separating portion 26b extending in the fore-and-aft direction of the case 26a and provided in a center portion of the case 26a in the left-and-right direction. member having a higher coefficient of friction than the case 26a is employed for the separating portion 26b.

As shown in FIG. 3, the pickup unit 24 includes a first arm 31 to be pivotably mounted on the supporting shaft 23, a second arm 32 to be pivotably mounted on a lower end of the first arm 31, and a feed roller 33 to be mounted on a lower end of the second arm 32. A torsion coil spring 35 as an urging member is mounted on the second arm 32. Accordingly, the feed roller 33 (the second arm 32) is urged toward the sheets P. The torsion coil spring 35 also causes a rotational force of the supporting shaft 23 to be transmitted to the feed roller 33 via a transmitting mechanism 34 including driven gears 34a to 34c.

The first arm 31 includes a pair of first arm portions 41 apart from each other in the left-and-right direction and an upper cover portion 42 configured to connect the first arm portions 41 with each other and cover the supporting shaft 23 from above. The first arm portions 41 each are provided with a first bearing portion 43 having a through hole penetrating therethrough in the left-and-right direction in upper portions thereof. Provided in a lower portion of the first arm portion 41 on the right side is a first shaft portion 44 projecting rightward from the first arm portion 41. Provided in a lower portion of the first arm portion 41 on the left side is a second shaft portion 45 having a through hole penetrating therethrough in the left-and-right direction. The supporting shaft 23 is slidably inserted through the first bearing portion 43. In this embodiment, the supporting shaft 23 and the first bearing portion 43 constitute a “first pivotal portion 61”.

The upper cover portion 42 is provided with an arcuate shaped curved portion 42a which surrounds the first pivotal portion 61 from the outside and is centered at the center of pivotal movement of the first pivotal portion 61. The curved portion 42a is provided over the range of the pivotal movement of the first arm 31. In the transporting apparatus 12 (see FIG. 5A), a maximum amount of sheets to be loaded is defined here by a gap G (see FIG. 5A) formed between the curved portion 42a and the placing surface 21a. Since the width of the gap G is not changed by the pivotal movement of the first arm 31, the maximum amount of sheets to be loaded is maintained to be always constant by the pivotal movement of the first arm 31.

The second arm 32 includes a pair of second arm portions 51 apart from each other in the left-and-right direction and a cover body 52 configured to cover upper portions and front portions of the second arm portions 51. Provided in the upper portion of the second arm portion 51 on the right side is a projection 53 having a through hole penetrating therethrough and projecting rightward from the second arm portion 51. Provided in an upper portion of the second arm portion 51 on the left side is a cylindrical-shaped second shaft portion 54 projecting leftward of the second arm portion 51. Provided in a lower portion of each of the second arm portions 51 is a third bearing portion 55, which is a through hole penetrating therethrough in the left-and-right direction. The second arm 32 is mounted on the first arm 31 by the second shaft portion 54 slidably inserted into the second bearing portion 45 and the first shaft portion 44 slidably inserted into the projection 53. In this embodiment, the second shaft portion 54 and the second bearing portion 45 constitute a “second pivotal portion 62” on the right side, and the projection 53 and the first shaft portion 44 constitute a “second pivotal portion 62” on the left side.

The torsion coil spring 35 is fitted on the projection 53 so as to be coaxial with the second pivotal portion 62. One of the end portions of the torsion coil spring 35 is fitted to a locking portion 56 provided on the second arm portion 51. The other end portion of the torsion coil spring 35 is fitted to the upper cover portion 42.

The feed roller 33 is provided with a roller body portion 33a which is to be fitted to the third bearing portions 55 and is formed into a cylindrical shape. A sliding contact member 33b which comes into abutment with the sheet and is a cylindrical rubber member is mounted on an outer peripheral surface of the roller body portion 33a. Provided at a left end of the roller body portion 33a is a gear portion 33c which engages with the driven gear 34c (see FIG. 4).

As shown in FIG. 4, the transmitting mechanism 34 includes the driven gears 34a to 34c. The driven gear 34a is fitted on the supporting shaft 23 so as to rotate integrally therewith. The driven gear 34b engages both the driven gears 34a, 34c. The driven gear 34c engages the gear portion 33c. As shown by hollow arrows in FIG. 4, when the driven gear 34a rotates counterclockwise in association with the counterclockwise rotation of the supporting shaft 23, the driven gear 34b rotates clockwise by the rotation of the driven gear 34a, and rotates the driven gear 34c counterclockwise. The feed roller 33 rotates clockwise in association with the rotation of the driven gear 34c.

Subsequently, a procedure from placing to transport of the sheets P by the transporting apparatus 12 will be described with reference to FIGS. 5A to 8B. The drawings with a suffix of B are diagrammatic drawings showing a relation between a force exerted to a periphery of the pickup unit 24 and an angle of the pickup unit 24, respectively. In FIGS. 5A to 7B, “normal sheets” which are relatively thin and flexible sheets are used as the sheets P.

Before placing the sheets P on the placing tray 21, the pickup unit 24 is arranged so that the feed roller 33 abuts against the placing surface 21a. The pickup unit 24 is formed so that a first inter-axis distance D1, which is a length of a straight line connecting a center of pivotal movement of the first pivotal portion 61 and a center of pivotal movement of the second pivotal portion 62, becomes smaller than a second inter-axis distance D2, which is a length of a straight line connecting a center of pivotal movement of the second pivotal portion 62 and an axis of rotation J of the feed roller 33.

As shown in FIGS. 5A and 5B, when placing the sheets P on the placing tray 21, a user places the sheets P on the upstream side of the feed roller 33 in the direction of transport, and moves the sheets P toward the downstream side. Then, the sheets P come into abutment against the feed roller 33. Therefore, a component force of the own weight of the sheets P along the placing surface 21a is exerted on the feed roller 33. Accordingly, as shown by a broken line in FIG. 5A, the first arm 31 and the second arm 32 of the pickup unit 24 pivot clockwise integrally about the first pivotal portion 61. In other words, the second arm 32 pivots about the first pivotal portion 61 while maintaining the angle of inclination with respect to the first arm 31. Then, the feed roller 33 moves away from the placing surface 21a and the sheets P pass through a gap between the feed roller 33 and the placing surface 21a. Accordingly, the sheets P come into abutment with the separation pad 26, and the feed roller 33 comes into abutment with the topmost surface of the sheets P.

As shown by a solid line in FIG. 5A, in a waiting state in which the sheets P are placed on the placing tray 21 and the rotation of the feed roller 33 is stopped, the pickup unit 24 is inclined toward the front by the torsion coil spring 35 as the first arm 31 moves downward, and maintains its posture in a state of inclining rearward as the second arm 32 moves downward.

When the number of the sheets P is decreased, the pickup unit 24 changes its position from a state shown by the broken line in FIG. 5A to a state shown by the solid line in FIG. 5A under its own weight. In other words, the pickup unit 24 moves in such a manner that the first arm 31 pivots about the first pivotal portion 61 so that the lower end thereof moves toward the sheets P (counterclockwise in FIG. 5A). Correspondingly, the second arm 32 pivots while maintaining the angle of inclination with respect to the first arm 31, that is, the first arm 31 and the second arm 32 pivot integrally toward the sheets P.

In the waiting state, the torsion coil spring 35 has a natural length. Therefore, a force urging the second arm 32 counterclockwise by the torsion coil spring 35 is not generated. In other words, a force which urges the feed roller 33 toward a sheet P1 as a first transported medium which is at the topmost position from among the sheets P exerted by the torsion coil spring 35 (hereinafter, referred to as “urging force S”) is not generated. Therefore, the feed roller 33 simply comes into abutment with the sheet P1. Since the feed roller 33 does not try to rotate, the frictional force f of the roller, which is a frictional force that the sheet P1 exerts on the feed roller 33 is “0”.

Here, an arm angle A, which is an angle formed by the first arm 31 and the second arm 32 in the waiting state is defined as a reference angle A1. An angle of inclination B, which is an acute angle formed by a straight line JL connecting the second pivotal portion 62 and the axis of rotation J of the feed roller 33 and the placing surface 21a, that is, an abutting surface of the sheet P1 with respect to the feed roller 33 in the waiting state is defined as a reference angle B1.

As shown in FIG. 6, in a state in which the rotational force of the feed roller 33 is transmitted to the sheets P, that is, in the state just moments before the transport of the sheet P1 by the rotation of the feed roller 33 (just-before-transport state), an inter-sheet frictional force F generated between the sheet P1 and a sheet P2 as a second transported medium which comes into abutment with the sheet P1 in the stacking direction (hereinafter, referred to as “inter-sheet frictional force F1”) becomes maximum. Furthermore, a separation load H, which is a load exerted by the separation pad 26 for separating the sheet P1 from the sheet P2 (hereinafter, referred to as “separation load H1”) becomes maximum. Accordingly, in order to transport the sheet P1, a force corresponding to a resultant of the inter-sheet frictional force F1 and the separation load H1 is required. Therefore, a force T for transporting the sheet P1 generated by the rotation of the feed roller 33 (hereinafter, referred to as “transporting force T1”) becomes maximum. The frictional force f of the roller corresponds to the reaction force of the transporting force T1, and hence is equal to the transporting force T1 in the just-before-transport state.

At this time, in the pickup unit 24, a force to cause the second arm 32 to pivot clockwise is exerted on the second arm 32 due to the frictional force f of the roller. Accordingly, the lower end of the first arm 31 pivots counterclockwise about the first pivotal portion 61 and an upper end of the second arm 32 pivots clockwise about the axis of rotation J of the feed roller 33. Consequently, the second pivotal portion 62 moves toward the sheets P. As a result of the movement of the second pivotal portion 62 as described above, the arm angle A becomes an angle A2, which is larger than the reference angle A1 (A1<A2), and the angle of inclination B becomes an angle B2, which is smaller than the reference angle B1 (B2<B1). The feed roller 33 moves toward the downstream side in the direction of transport of the sheets P more than that in the waiting state as the arm angle A and the angle of inclination B vary. Accordingly, an urging force S1 is applied toward the downstream side in the direction of transport more than the case where an imaginary urging force SK generated when assuming that the urging force S1 is exerted in the waiting state.

In contrast, in comparison with the pivotal movement of the second pivotal portion 62, the torsion coil spring 35 is bent in the opposite direction from an urging direction. Accordingly, a restoration force R1 of the torsion coil spring 35 is exerted on the second arm 32. In other words, the urging force S1 corresponding to the above-described restoration force R1 is exerted on the second arm 32. Accordingly, the torsion coil spring 35 is bent in the direction opposite from the urging direction as the arm angle A increases from the reference angle A1, and hence the restoration force R1 of the torsion coil spring 35 increases.

Here, since the angle of inclination B is the angle B2, a force which causes the feed roller 33 to dig into the sheet P1 generated by the frictional force f of the roller (f·sinB2) is smaller than a force which causes the feed roller 33 to dig into the sheet P1 generated when assuming that the frictional force f of the roller is generated also at the reference angle B1 in the waiting state (f·sinB2<f·sinB1).

As shown in FIGS. 7A and 7B, in a state in which the sheet P1 is transported with respect to the sheet P2 (the sheet-transporting state), a frictional force F2 between the sheet P1 and the sheet P2 is smaller than the frictional force F1 generated in the just-before-transport state shown in FIG. 5B (F2<F1). Furthermore, since the sheet P1 and the sheet P2 are separated, the separation load H is “0”. Accordingly, since a force corresponding to the frictional force F2 is required in order to maintain the transporting state of the sheet P1, a transporting force T2 in the sheet-transporting state is smaller than a transporting force T1 (T2<T1). Accordingly, the frictional force f of the roller corresponds to the transporting force T2, and hence is smaller than that in the just-before-transport state.

At this time, in the pickup unit 24, the lower end of the first arm 31 pivots clockwise as the frictional force f of the roller decreases, and the upper end of the second arm 32 pivots counterclockwise. Accordingly, the second pivotal portion 62 moves away from the sheet P. Consequently, the arm angle A becomes an angle A3 between the angle A1 and the angle A2 (A2<A3<A1). The angle of inclination B becomes an angle B3 between the angle B1 and the angle B2 (B1<B3<B2). The feed roller 33 is moved toward more upstream side than in the just-before-transport state and toward more downstream side than in the waiting state as the arm angle A and the angle of inclination B vary.

In association with the movement of the second pivotal portion 62, the torsion coil spring 35 is bent in the same direction as the urging direction, and hence a restoration force R2 at this time becomes smaller than the restoration force R1 (R2<R1). Accordingly, an urging force S2 becomes smaller than the urging force S1 (S2<S1).

In this manner, in the pickup unit 24, the frictional force f of the roller, the transporting force T, the urging force S, and the angle of inclination B vary respectively with the transition thereof from the waiting state to the paper transporting state. In other words, the urging force S increases and the angle of inclination B decreases with the increase in the transporting force T (the frictional force f of the roller).

The frictional force f of the roller, the urging force S, the transporting force T, and the angle of inclination B are also changed respectively with the difference of the thickness of the sheet P. In other words, when the thickness of the sheet P is different, the separation load H is changed, and hence the frictional force f of the roller is changed correspondingly. More specifically, the separation load H as shown in FIGS. 8A and 8B is larger in the case of sheets P3 which are thick like “photo sheets” or “postcards” than in the case of the sheets P1 which are thin as the normal paper shown in FIGS. 6A and 6B. Accordingly, the frictional force f of the roller is larger in the case where the sheet P3 is transported in the just-before-transport state than in the case where the sheet P1 is transported. Accordingly, the transporting force T3 for transporting the sheet P3 is larger than the transporting force T1, and hence an angle B4 taken when the sheet P3 is transported is smaller than the reference angle B1 taken when the sheet P1 is transported (B4<B1).

According to the embodiment described above, the following effects are achieved.

(1) The pickup unit 24 includes the first pivotal portion 61 and the second pivotal portion 62, and also includes the torsion coil spring 35 which exerts an urging force to the second arm 32, mounted on the second pivotal portion 62. Accordingly, in the just-before-transport state and the sheet-transporting state, a component force of the frictional force f of the roller is exerted on the second arm 32 as a force to cause the second arm 32 to pivot clockwise. With the action of this force, the first arm 31 pivots counterclockwise about the first pivotal portion 61 and the second arm 32 pivots clockwise about the axis of rotation J of the feed roller 33, so that the second pivotal portion 62 moves toward the sheets P. Consequently, the angle of inclination B is decreased with the movement of the second pivotal portion 62 in comparison with the waiting state.

Furthermore, a restoration force is generated in the torsion coil spring 35 by the movement of the second pivotal portion 62, and the restoration force of the torsion coil spring 35 exerts an urging force in the direction toward the sheets P on the second arm 32. This urging force increases in proportion to the increase in the restoration force of the torsion coil spring 35.

Therefore, the urging force that the torsion coil spring 35 exerts on the second arm 32 is increased and the angle of inclination B is decreased, and hence the degree of increase in the frictional force f of the roller is smaller than the degree of increase in the urging force. Consequently, the frictional force f of the roller can be prevented from being excessive with respect to the inter-sheet frictional force F, whereby multi feed of the sheets P can be restrained.

Incidentally, a demand for downsizing of the transporting apparatus is increasing with downsizing of the printer. In order to meet this demand, downsizing of the pickup unit is conceivable. In other words, achieving the downsizing by reducing the length of an arm 130 shown in FIGS. 9A and 9B is conceivable. However, when the length of the arm 130 is reduced, the acute angle Y becomes larger than the acute angle Y shown in FIGS. 9A and 9B, and hence the digging of a feed roller 120 into a sheet Q is increased. Therefore, it is required to reduce the acute angle in order to restrain the digging described above, and hence it is required to increase the length of the arm 130, that is, it is required to arrange a drive shaft 140 at an upper position. However, in this case, there arises a problem of upsizing of the transporting apparatus.

In this respect, according to this embodiment, by causing the second arm 32 to incline with respect to the first arm 31, the angle of inclination B corresponding to the above-described acute angle is decreased with increase in the frictional force f of the roller in conjunction with the pivotal movement of the second pivotal portion 62 without changing the position of the supporting shaft 23. Therefore, occurrence of the digging as described above can be restrained. Therefore, both the downsizing of the transporting apparatus 12 and restraint of the digging are achieved.

In particular, in a transporting apparatus 100 shown in FIGS. 9A and 9B, the acute angle (the angle of inclination B) is set irrespective of the separation load and the inter-sheet frictional force of the sheet Q because the acute angle varies according to the amount of loaded sheets Q. Accordingly, if the amount of loaded sheets Q is small, the frictional force that the sheet Q exerts the feed roller 120 (the frictional force of the roller) is increased even though the separation load or the inter-sheet frictional force is not change.

In this respect, according to this embodiment, since the angle of inclination B varies with the transporting force T including the separation load H and the inter-sheet frictional force F, the force to cause the feed roller 33 to dig into the sheet P1 (f·sinB) generated by the frictional force f of the roller can be prevented from becoming excessive.

(2) The magnitude of the separation load H is different depending on the type of the sheets even when the numbers of the sheets are the same. For example, when comparing the normal sheet and the postcard, the thickness of the postcard is larger than that of the normal sheet. Therefore, the separation load H of the postcard is higher correspondingly. In contrast, in the transporting apparatus 100 shown in FIGS. 9A and 9B, the position of the feed roller 120 can be adjusted according to the number of sheets, but a press-contact force of the feed roller 120 against the sheets cannot be changed according to the types of the sheets. Therefore, when the transporting apparatus 100 is set with reference to the separation load H for the postcard, for example, the multi feed may occur when transporting the normal sheets if the amount of normal sheets is small. In contrast, when the transporting apparatus 100 is set with reference to the separation load H for the normal paper, the feed roller 33 may turn free due to insufficient transporting force T thereof if the amount of thick sheets is small.

In this regard, according to this embodiment, since the urging force S of the pickup unit 24 increases with the increase in the separation load H, when the sheets P are thick like postcards, the transporting force T of the feed roller 33 increases correspondingly. In contrast, since the urging force S of the pickup unit 24 decreases according to the decrease in the separation load H, when the sheets P are thin like the normal sheets, the transporting force T decreases correspondingly. Accordingly, even when the separation load H is different according to the difference in thickness of the sheets P, the multi feed of the sheets P and the free turning of the feed roller 33 can be restrained.

(3) Since the first inter-axis distance D1 is smaller than the second inter-axis distance D2, the distance of the pivotal movement of the second pivotal portion 62 is larger than that in the case where the first inter-axis distance is larger than the second inter-axis distance. Accordingly, a range of adjustment of the urging force exerted on the feed roller 33 toward the sheet P1 by the restoration force of the torsion coil spring 35 can be increased.

(4) In the just-before-transport state, the inter-sheet frictional force F and the separation load H become maximum respectively, and hence the transporting force T becomes maximum correspondingly. In contrast, since the second pivotal portion 62 pivots to make the angle of inclination B minimum, the increase in the frictional force f of the roller can be restrained. Therefore, the feed roller 33 can be prevented from digging into the sheet P1.

(5) When the second pivotal portion 62 is provided with a mechanism which restricts the number of sheets P to be placed, the second pivotal portion 62 moves toward or away from the sheets P in association with the pivotal movement of the first arm 31 and the second arm 32 in a circumstance in which the feed roller 33 transports the sheets P. Therefore, the position of the second pivotal portion 62 with respect to the placing surface 21a changes. Consequently, the position to restrict the number of sheets P to be placed changes as well. Accordingly, the extent of allowable amount of the sheets P to be placed thereon cannot be defined accurately.

In this regard, according to the embodiment of the invention, since the curved portion 42a of the upper cover portion 42 covers the first pivotal portion 61 from the outside in the direction of the radius of the pivotal movement of the first pivotal portion 61, the position of the curved portion 42a with respect to the placing surface 21a does not change even when the first pivotal portion 61 is pivoted. Therefore, the positions of the placing surface 21a and the curved portion 42a do not change in the circumstance in which the feed roller 33 transports the sheet P. Accordingly, the maximum amount of sheets P to be loaded (the number of sheets P to be loaded) can be defined accurately.

Furthermore, since the curved portion 42a of the upper cover portion 42 is provided over the range of the pivotal movement of the first arm 31, the sheet P is restrained from deviating from the gap G formed by the placing surface 21a and the curved portion 42a in the course of the pivotal movement of the first arm 31.

(6) When the feed roller 33 moves toward the downstream side in the direction of transport of the sheet P in association with the increase in the urging force S, the distance between the feed roller 33 and the separation pad 26 decreases. Accordingly, since the elasticity of the sheet P when a leading end of the sheet P comes into abutment with the separation pad 26 becomes relatively stronger, the sheets P are separated adequately.

Furthermore, since the urging force S is directed toward the downstream side as the urging force S increases, the degree of increase in the component force toward the upstream side of the urging force S becomes small with respect to the degree of increase in the urging force S. Accordingly, the degree of increase in the frictional force f of the roller with respect to the degree of increase in the urging force S decreases. Therefore, the feed roller 33 can be prevented from digging into the sheet P1.

(7) In the just-before-transport state as shown in FIGS. 6A and 6B, or FIGS. 9A and 9B, the pivotal movement of the second pivotal portion 62 is restricted to a position apart from the sheets P1 and P3. Accordingly, even when the second pivotal portion 62 pivots toward the sheets P1 and P3, the second pivotal portion 62 is avoided from coming into abutment with the sheets P1 and P3. Therefore, the sheets P1 and P3 can be transported adequately by the transporting apparatus 12.

The embodiment described above may be modified as follows.

In the embodiment described above, the first inter-axis distance D1 between the first pivotal portion 61 and the second pivotal portion 62 may be equivalent to or larger than the second inter-axis distance D2 between the second pivotal portion 62 and the axis of rotation J of the feed roller 33.

In the embodiment described above, the separation pad 26 may be omitted.

In the embodiment described above, the curved portion 42a of the upper cover portion 42 may be provided over a range smaller than the range of pivotal movement of the first pivotal portion 61. The curved portion 42a may also be omitted.

In the embodiment described above, the direction of transport of the sheet P may be a direction along the fore-and-aft direction. In this case, the feed roller 33 comes into abutment with an upper surface of the sheet P. In the waiting state, the second arm 32 is inclined upward as it goes to the upstream side in the direction of transport. The first arm 31 is inclined downward as it goes to the upstream side in the direction of transport. When the just-before-sheet transport state is assumed, the arm angle A increases and the angle of inclination B decreases. Accordingly, the feed roller 33 moves toward the downstream side in the direction of transport. When the restoration force R of the torsion coil spring 35 increases in association with the movement of the feed roller 33, the urging force S of the feed roller 33 increases. In the paper transporting state, the arm angle A decreases and the angle of inclination B increases in comparison with the just-before-transport state. Accordingly, the feed roller 33 moves toward the upstream side in the direction of transport. Accordingly, the restoration force R of the torsion coil spring 35 decreases, and hence the urging force S of the feed roller 33 decreases correspondingly.

In the embodiment described above, the torsion coil spring 35 may be mounted on the first arm 31. In this case as well, the restoration force R of the torsion coil spring 35 increases and decreases in association with the pivotal movement of the second pivotal portion 62 by fitting both end portions of the torsion coil spring 35 to the first arm 31 an the second arm 32, respectively.

In the embodiment described above, a leaf spring may be employed instead of the torsion coil spring 35. In this case, the restoration force of the leaf spring increases and decreases because the leaf spring is bent in association with the pivotal movement of the second pivotal portion 62 by fitting the both end portions of the leaf spring to the first arm 31 and the second arm 32, respectively. A coil spring may be employed instead of the torsion coil spring 35. In this case, the restoration force of the coil spring increases and decreases because the leaf spring is expanded in association with the pivotal movement of the second pivotal portion 62 by fitting both end portions of the coil spring to the first arm 31 an the second arm 32, respectively.

In the embodiment described above, a configuration in which a shaft portion corresponding to the second shaft portion 54 is provided on the first arm 31 as a second fitting portion and a second shaft member, and a bearing portion corresponding to the second bearing portion 45 is provided on the second arm 32 is also applicable.

In the embodiment described above, the pickup unit 24 may be provided on a part of the placing tray 21 or other portion of the printer 11. In this case, the above-described portion and the first bearing portion 43 constitute a first pivotal portion. In this case, a configuration in which the above-described portion is formed into a shape corresponding to the first bearing portion 43 and a shaft potion to be fitted to the above-described portion is provided on the first arm 31 is also applicable.

In the embodiment described above, sheets other than the normal sheets, the photo sheets, and the postcards such as OHP, for example, may be transported as the transported media that the transporting apparatus 12 transports.

In the embodiment described above, the transporting apparatus 12 is not limited to be applied to the ink jet printer 11, and may be applied, for example, to a dot-impact printer, a laser printer, a thermal-transfer printer, and so on. The application of the transporting apparatus 12 is not limited to the printer, and the transporting apparatus 12 may be applied to other apparatuses which transport the transported media.

The entire disclosure of Japanese Patent Application No. 2010-088038, filed Apr. 6, 2010 is expressly incorporated by reference herein.

Claims

1. A transporting apparatus comprising: a transporting apparatus body configured to transport a transported medium by a feed roller;a first arm to be mounted on the transporting apparatus body so as to be pivotable about a first pivotal portion with respect to the transporting apparatus body;a second arm mounted on the first arm so as to be pivotable about a second pivotal portion with respect to the first arm and fixed with the feed roller at a position opposite from the first pivotal portion with respect to the second pivotal portion; andan urging member acting on the second pivotal portion so as to urge the feed roller toward the transported medium.

2. The transporting apparatus according to claim 1, comprising: a separating mechanism configured to separate a first transported medium in abutment with the feed roller from a second transported medium adjacent to the first transported medium in a stacking direction,wherein the second arm moves toward a direction in which a rotational force of the feed roller acts on the first transported medium against an urging force of the urging member when a load for separating the first transported medium and the second transported medium exerted by the separating mechanism is large, whereby the urging force of the feed roller with respect to the first transported medium increases.

3. The transporting apparatus according to claim 1, wherein a first inter-axis distance, which is a distance connecting the first pivotal portion and the second pivotal portion with a straight line is smaller than a second inter-axis distance, which is a distance connecting the second pivotal portion and the axis of rotation of the feed roller with a straight line.

4. The transporting apparatus according to claim 1, wherein when a state in which the rotation of the feed roller is stopped is changed to a state in which the rotational force of the feed roller is transmitted to the transported medium, the second pivotal portion pivots so that an acute angle formed by an axial line connecting the axis of rotation of the feed roller and the second pivotal portion and the transported medium becomes minimum.

5. The transporting apparatus according to claim 1, wherein the transporting apparatus is provided with a placing surface for placing the transported medium at a position opposing the feed roller, a cover configured to cover the first pivotal portion from the outside thereof in the direction of the radius of the pivotal movement of the first pivotal portion, and restrict the number of the transported media to be placed by a gap formed in cooperation with the placing surface is provided at a portion of the first pivotal portion opposing the transported medium, andthe cover is provided over a range of the pivotal movement of the first arm in association with the action of the feed roller which transports the transported medium.