JP3818403B2 - Paper transport device and printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a sheet conveying apparatus that conveys stacked sheets placed downstream to the downstream side and conveys the sheets further downstream while accurately controlling the sheet feeding amount, and a printer including the sheet conveying apparatus. .
[0002]
[Prior art]
  Conventionally, as a paper transport device mounted on an ink jet printer, a paper feed cassette that stacks and stores a large number of paper sheets and a position that contacts the upper surface of the paper in the paper feed cassette are rotated and rotated once. A sheet feed roller that feeds only one sheet to the downstream side, and abutting against the leading edge of the sheet fed by the sheet feed roller to temporarily stop the sheet, and then sucking the sheet into the print head A thing provided with the conveyance mechanism sent out to the front is known.
[0003]
  This type of paper transport device makes the front end of the paper contact the transport mechanism and temporarily stops the paper, thereby accurately positioning the position and orientation of the front end of the paper with respect to the transport mechanism, and then transports the paper. By operating the mechanism, an attempt is made to accurately control the paper feed amount according to the operation amount of the transport mechanism.
[0004]
  By the way, in the paper transport device, since the paper feed roller sends out the paper and the transport mechanism sucks the paper, the relationship between the feed speed on the paper feed roller side and the suction speed on the transport mechanism side, or the paper feed roller is set. Depending on the power transmission mechanism to be driven, the paper may be pulled between the paper feed roller side and the transport mechanism side, and the suction of the paper into the transport mechanism may not be performed smoothly.
[0005]
  Therefore, conventionally, in order to prevent such a situation, when the paper is brought into contact with the transport mechanism, the paper is sent out slightly more than the distance of the transport path from the paper feed roller to the transport mechanism, and the fed paper is It was made to bend with the contact with the transport mechanism. In this case, even if the suction speed on the transport mechanism side is slightly higher than the feed speed on the paper feed roller side, for example, the paper feed roller temporarily stops when the transport mechanism sucks the paper, By extending the amount of bending, an excessive tension is not applied to the sheet, and the sheet is smoothly sucked into the conveyance mechanism.
[0006]
[Problems to be solved by the invention]
  However, the prior art has the following problems.
[0007]
  Paper used for printing with inkjet printers varies in thickness, from relatively thin paper to thick paper such as postcards and envelopes. However, the above conventional paper transport devices use thick paper. In this case, as described above, even if an attempt is made to feed the paper a little longer than the distance of the transport path from the paper feed roller to the transport mechanism, if the fed paper comes into contact with the transport mechanism, the paper and the paper are fed thereafter. In some cases, slip occurs between the rollers and the paper does not bend. When the transport mechanism starts sucking the paper in such a situation, as described above, the paper is pulled between the paper feed roller side and the transport mechanism side, that is, the paper feed roller at the start of suction by the transport mechanism. Becomes a load, and there is a case where the sheet is not smoothly sucked by the transport mechanism. As a result, printing may not be performed at a desired position, for example, printing may be started without proper paper feeding, and the margin on the front end side of the paper may be less than expected.
[0008]
  The present invention has been made to solve these problems, and an object of the present invention is to provide a paper transport device that can smoothly and accurately feed paper regardless of the thickness of the paper, and a printer including the paper transport device. It is to provide.
[0009]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a sheet transporting apparatus, comprising: a sheet stacking unit capable of stacking and stacking a plurality of sheets; and a sheet stacking unit configured to store sheets stacked on the sheet stacking unit. Rotates at a position where it contacts the upper surface, and abuts against the paper feed roller that feeds the paper downstream by the frictional force generated with the paper and the leading edge of the paper fed by the paper feed roller. A paper transporting device having a transport mechanism for temporarily stopping the paper and then transporting the paper downstream.A placement position guide provided in the paper stacking unit and slidable in a direction crossing a paper delivery direction;After the leading edge of the sheet fed to the paper feed roller comes into contact with the transport mechanism, the paper stacking unit and / or the paper feed roller is operated to temporarily increase the distance between the two.It is possible to select the operation and non-operation of the interval expanding means by moving the placement position guide.It is characterized by that.
[0010]
  According to the paper transport device of the present invention, after the leading edge of the paper fed to the paper feed roller comes into contact with the transport mechanism, the interval enlarging means has one or both of the paper stacking unit and the paper feed roller (that is, the paper Since the interval between the paper stacking unit and the paper feed roller is temporarily increased by operating the paper stacking unit and / or paper feed roller), when the transport mechanism starts sucking paper, paper is fed to the paper to be transported. The roller is not pressed. Therefore, in particular, when relatively thick paper, for example, a postcard is used, the paper is pulled between them regardless of the operation speed on the paper feed roller side and the transport mechanism side, that is, the transport mechanism is fed. The paper roller does not become a load, and the paper is sucked smoothly by the transport mechanism.Further, it is possible to select the operation and non-operation of the interval enlargement means by moving the placement position guide. Accordingly, proper paper feeding is always performed, and printing recording can be performed at a predetermined position.
[0011]
  Here, as long as the interval enlargement unit can temporarily increase the interval between the paper stacking unit and the paper feed roller by operating either one or both of the paper stacking unit and the paper feed roller, The specific structure may be any structure. To give a more specific example, for example, as shown in claim 2, the paper stacking portion is biased toward the paper feed roller. The gap expanding means includes a cam that rotates in conjunction with the paper feed roller, and the cam stacking unit is moved away from the paper feed roller against the biasing force of the biasing means. It is good to be comprised so that it may push back in the direction to leave | separate temporarily.Further, the loading position guide is configured to be slidable in a direction intersecting with the sheet carry-out direction, and the movement and non-operation of the interval expanding means can be selected by moving the loading position guide.
[0012]
  In the paper transporting apparatus according to the second aspect, the paper stacking portion side has a movable structure, and the paper stacking portion is normally biased toward the paper feed roller by the biasing means. AndOnly when the mounting position guide is at a specific positionThe interval enlarging means pushes back the sheet stacking portion against the urging force of the urging means by the cam rotating in conjunction with the sheet feeding roller, and temporarily widens the interval with the sheet feeding roller. With this configuration, the paper stacking unit is pushed back at a predetermined timing synchronized with the rotation angle of the paper feed roller, so that the paper is fed by a predetermined length without separately detecting the paper transport position and transport speed. After that, the interval enlargement means can function.
[0013]
  Further, in this case, in particular, as described in claim 3, if the cam is provided on the same rotation shaft as the paper feed roller, the cam can be easily mounted without using a complicated mechanism using a gear or the like. It can be interlocked with the paper feed roller, and the desired effect can be obtained sufficiently.
[0014]
  As the urging means, springs such as a coil spring and a leaf spring can be usually used. However, other means such as a motor may be used as a power source to push up the paper stacking portion toward the paper feed roller. . In addition to the structure according to the second aspect, for example, the sheet conveying apparatus of the present invention may be configured such that the sheet feeding roller side is a movable structure and is separated from the sheet stacking unit side. However, if the paper stacking unit has a structure that lifts the remaining paper to the paper feed roller side as the paper is consumed, the paper can be fed from the paper feed roller side if the structure is operated in reverse. Therefore, a sufficiently satisfactory effect can be obtained even if the paper feed roller side does not have a movable structure.
[0015]
  Furthermore, as claimed in claim 4, a sun gear that is driven to rotate in either the forward or reverse direction in conjunction with the transport mechanism, and a pair provided around the sun gear, each meshing with the sun gear. The first and second planetary gears that move around the sun gear in a forward or reverse direction while rotating, and the forward rotation of the sun gear meshes with the first planetary gear while rotating forward, A feed gear that meshes with the second planetary gear via an intermediate gear to rotate in the forward direction and rotates the feed roller in the forward direction when the sun gear rotates in the reverse direction; When the sheet rotates in the reverse direction, the sheet is fed out to the sheet feeding roller so that the leading edge of the sheet contacts the transport mechanism.Only when the above-mentioned position guide is at a specific positionIf the gap enlarging means widens the gap between the paper stacking unit and the paper feed roller, the paper feed roller that should always rotate in the forward direction can be linked to the transport mechanism that operates in both the forward and reverse directions. In addition, the sheet feeding operation can be controlled by a single motor without dividing the motor for the sheet feeding roller and the transport mechanism. In particular, in a situation where the transport mechanism operates in the reverse direction and does not transport the paper,Only when the above-mentioned position guide is at a specific positionSince the interval enlargement means widens the interval between the paper stacking unit and the paper feed roller, when the sun gear switches from reverse rotation to normal rotation and the transport mechanism starts sucking the paper, the paper feed roller Is not in pressure contact. For this reason, when using relatively thick paper, for example, a postcard, the paper feed roller is temporarily stopped until the first planetary gear meshes with the paper feed gear. Even if there is a difference in operating speed on the side, the suction of the paper into the transport mechanism is always performed smoothly.
[0016]
  Next, according to a fifth aspect of the present invention, there is provided a printer according to the fifth aspect, further comprising the above-described paper transport device, and further including a print head for printing on the paper on the downstream side of the transport mechanism. Features. With such a configuration, the sheet conveying device functions as described above, and the sheet can be conveyed accurately and smoothly to the front of the print head, and printing can be recorded at an expected position on the leading end side of the sheet. it can.
[0017]
  For such a printer, various specific configurations can be conceived. For example, as described in claim 6, if the print head is an ink jet head that ejects ink droplets to perform printing, the paper transport function is improved. An excellent ink jet printer can be constructed.
[0018]
  Note that the paper conveying apparatus of the present invention can be mounted even with a printer having a print head of a system other than the ink jet type. Further, not only the printer but also the paper conveyance device of the present invention may be mounted on a facsimile machine or the like.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments of the present invention will be described with reference to the drawings. Note that the specific devices and the like described below are merely examples of the embodiments of the present invention, and the embodiments of the present invention are not limited to the specific ones exemplified below.
[0020]
  As shown in FIG. 1, the ink jet printer 2 feeds a sheet one sheet at a time from the sheet feeding cassette 4 that stores a large number of sheets in a stacked state and the sheet feeding cassette 4 as the sheet is rotated. A paper feed roller 6, an arm 7 swingably provided above the conveyance path, and a pressure that is rotatably provided at the tip of the arm 7 and presses a sheet passing through the conveyance path below the arm 7 from the upper surface side. A feed roller 10 is provided that feeds the paper to the front of the print head 12 as it is driven to rotate while sandwiching the paper between the roller 8 and the pressure roller 8. The pressure roller 8 and the feed roller 10 jointly constitute a transport mechanism. Among these, the paper feed cassette 4 includes a paper stacking portion, that is, a paper stacking plate 23 on which a large number of sheets P are stacked and placed on the upper surface, and the paper stacking plate 23 is a support shaft 21 at the upstream end in the transport direction. The downstream end is biased by a biasing means, that is, a spring 25 in a direction in which the paper P on the paper stacking plate 23 comes into contact with the paper feed roller 6. The paper stacking plate 23 is provided with a placement position guide 24 slidable in the width direction of the paper. The placement position guide 24 can hold the paper at an appropriate position according to the paper width.
[0021]
  Further, as shown in FIG. 2, the paper feed roller 6 is fixed to the rotating shaft 27 and rotates as the rotating shaft 27 rotates. In addition to the paper feed roller 6, the rotary shaft 27 is provided with a cam 28 and a disk-shaped spacer 29. The cam 28 is fixed to the rotating shaft 27 and rotates as the rotating shaft 27 rotates. At this time, the cam 28 abuts against a contact portion 23 a protruding outside the sheet width range on the upper surface of the sheet stacking plate 23, The paper stacking plate 23 is temporarily pushed down. The disc-shaped spacer 29 is provided so as to be rotatable with respect to the rotating shaft 27. The paper feed roller 6 has a large-diameter outer peripheral portion 6a whose diameter is slightly larger than that of the spacer 29 and a small-diameter outer peripheral portion 6b whose diameter is smaller than that of the spacer 29. It is made of rubber with a relatively high coefficient of friction. The circumferential length of the large-diameter outer peripheral portion 6a is sufficiently larger than the distance from the front end of the sheet placing plate 23 to the contact position between the pressure roller 8 and the feed roller 10. The disk-shaped spacer 29 abuts on the paper P on the paper stacking plate 23 when the paper feed roller has the small-diameter outer peripheral portion 6b facing the paper stacking plate 23, and keeps the paper feed roller 6 and the paper P at a predetermined interval. . In addition, the cam 28 and the contact part 23a comprise a space | interval expansion means.
[0022]
  As shown in FIG. 1, the arm 7 is provided so as to be swingable about a support shaft 31, and is urged by a spring 33 to press the pressure roller 8 against the feed roller 10. The feed roller 10 is driven to rotate in both forward and reverse directions, and during reverse rotation (counterclockwise in FIG. 1), even if the leading edge of the paper P reaches the contact position between the pressure roller 8 and the feed roller 10, the paper While not sucking P, the paper P is temporarily stopped at that position, while at the time of forward rotation (clockwise in FIG. 1), the paper P that has reached the contact position with the pressure roller 8 is immediately sucked and printed. It can be sent out to the front of the head 12.
[0023]
  Further, as shown in FIG. 3A, the ink jet printer 2 is a stepping that can be rotationally driven in both forward and reverse directions as a power transmission mechanism for rotationally driving the paper feed roller 6, the feed roller 10 and the like. A motor 41, a motor gear 42 that is coaxially fixed to the drive shaft of the stepping motor 41, is driven to rotate, a reduction gear 43 that is meshed with the motor gear 42 at a large diameter portion, and is rotated, and the feed roller 10. A feed gear 44 fixed coaxially to the end, meshed with the small diameter portion of the reduction gear 43 and rotated integrally with the feed roller 10, a sun gear 45 meshed with the feed gear 44, and rotated; A pair of support frames 46 provided so as to be swingable about the rotation axis of the gear 45 and a pair of the support frames 46 are engaged with the sun gear 45 to rotate. The support frame 46 is swung, and the first planetary gear 47 and the second planetary gear 48 that move (revolve) around the sun gear 45 according to the swinging motion, and the support frame 46 is swung during the forward rotation of the sun gear 45. As the sun gear 45 rotates in the reverse direction, it meshes with the first planetary gear 47 along with the movement, and as the support frame 46 swings, it meshes with the second planetary gear 48 and the intermediate gear 49 to rotate in the normal direction. , And a paper feed gear 50 that is rotationally driven integrally with the paper feed roller 6.
[0024]
  Next, a paper feeding operation of this ink jet printer will be described.
[0025]
  First, in the initial state (that is, the state in which the previous paper feeding operation is completed and the next paper feeding operation is not started), the gear mechanism is in the state shown in FIG. The paper roller 6 has a small-diameter outer peripheral portion 6 b facing the paper P. In this state, as shown in FIG. 1, since the spacer 29 is in contact with the paper P, the paper feed roller 6 is separated from the paper P.
[0026]
  Next, when the paper feeding operation is started, the stepping motor 41 is rotationally driven in the reverse direction (counterclockwise in FIG. 3A), and the gear mechanism is operated accordingly, and the feed gear 44 is rotated counterclockwise in the drawing. , And the feed roller 10 that rotates integrally therewith also reversely rotates. As a result, the conveyance of the sheet downstream from the feed roller 10 is prevented.
[0027]
  On the other hand, since the support frame 46 swings clockwise in the figure at this time, the second planetary gear 48 meshes with the intermediate gear 49, and the feed gear 50 meshing with the intermediate gear 49 starts rotating counterclockwise in the figure. The sheet feeding roller 6 that rotates together with the rotation starts to rotate counterclockwise in the figure.
[0028]
  When the paper feed roller 6 starts to rotate, the large-diameter outer peripheral portion 6a comes into contact with the paper P and feeds only one paper P downstream by the frictional force generated between the paper P and the paper P. When the sheet P is fed by a predetermined length, the sheet P comes into contact with the contact position between the pressure roller 8 and the feed roller 10.
[0029]
  After this contact, when the paper feed roller 6 rotates to the state shown in FIG. 3R> 3 (b), the cam 28 contacts the contact portion 23a of the paper stacking plate 23 as shown in FIG. The paper stacking plate 23 is temporarily pushed down in the direction of arrow A in the figure, and the paper P is separated from the paper feed roller 6. At substantially the same time, when the stepping motor 41 rotates a predetermined number of steps from the beginning, the rotation direction is switched and the rotation is driven in the forward direction (clockwise in FIG. 3C), and the gears are accordingly rotated. As shown in FIG. 3C, the mechanism operates and the feed gear 44 rotates clockwise as shown in the figure, and the feed roller 10 that rotates integrally with the feed gear 44 also rotates forward. As a result, the conveyance of the sheet downstream from the feed roller 10 is started.
[0030]
  At this time, since the support frame 46 swings counterclockwise in the drawing, the second planetary gear 48 is separated from the intermediate gear 49, and this time, the first planetary gear 47 meshes with the paper feed gear 50. The paper feed gear 50 stops only for a short time until it meshes with the first planetary gear 47. At this time, the paper feed roller 6 is not in pressure contact with the paper P. Regardless of the operation on the side of the feed roller 10 with respect to the speed “0”, the sheet P is not pulled between them, and the sheet P is sucked smoothly. The paper feed gear 50 meshes with the first planetary gear 47 and simultaneously starts to rotate counterclockwise in the figure as before, and the paper feed roller 6 that rotates integrally therewith also starts to rotate counterclockwise in the figure.
[0031]
  When the paper feed roller 6 starts to rotate, the large-diameter outer peripheral portion 6a that has come into contact again slightly pushes out the paper P, and subsequently the small-diameter outer peripheral portion 6b comes to a position facing the paper P. The outer peripheral portion 6 b does not contact the paper P. For this reason, after the feeding by the feed roller 10 is started, no frictional force acts between the paper feeding roller 6 and the paper P, and no matter how the paper feeding roller 6 moves, there is no useless influence on the feeding by the feeding roller 10. It will not reach.
[0032]
  The paper feed gear 50 has a missing portion 50a that is not provided with teeth that mesh with the first planetary gear 47, and when the missing portion 50a reaches the position of the first planetary gear 47, the meshing of the two is completed. After that, the rotation of the feed roller 10 is continued, but the paper feed roller 6 stops at the initial position shown in FIG. 3A and is driven until the next paper feed operation is started. There is nothing.
[0033]
  In the ink jet printer 2, if the sheet is ordinary thin paper, the sheet feeding roller 6 rotates to the state shown in FIG. 3B even after contacting the contact position between the pressure roller 8 and the feed roller 10. The sheet is bent by a sufficient amount between the sheet roller 6 and the transport mechanism 7, and the leading end of the sheet is positioned at the contact position between the pressure roller 8 and the feed roller 10, and the inclination is corrected. The leading edge of the paper is positioned at the contact position between the pressure roller 8 and the feed roller 10, and the inclination is corrected. Even if the interval between the paper P and the paper feed roller 6 is temporarily widened by the cam 28, it is possible to print and record accurately from a position where a predetermined margin is provided at the front end of the paper.
[0034]
  In the case of a thick sheet such as a postcard, that is, a sheet having high rigidity, the above-described bending cannot be sufficiently performed, and the sheet feeding roller 6 slips. When the feed roller 10 starts to rotate in the direction in which the paper is conveyed to the print head 12 side, the paper 28 is pulled against the paper feed roller 6 that has been stopped in the prior art. Since the paper stacking plate 23 is pushed down against the urging force and the interval with the paper feed roller 6 is temporarily increased, the paper feed roller 6 is not pressed against the paper P, and the paper feed roller 6 and the feed roller 10 The paper is not pulled between. As a result, the paper is always properly fed by the feed roller 10 and printing can be recorded at a desired position.
[0035]
  Next, another specific example (hereinafter referred to as specific example 2) in which the configuration corresponding to the cam 28 and the contact portion 23a is different from the specific example (hereinafter referred to as specific example 1) will be described. Since the other configuration is the same as that of the first specific example, the same reference numeral is given to the same configuration as the first specific example, and a detailed description thereof is omitted.
[0036]
  As shown in FIG. 5, the ink jet printer of Example 2 includes two cams 28 a and 28 b on the rotating shaft 27 on which the paper feed roller 6 is provided. Further, a contact piece 24 a corresponding to the contact portion 23 a of the specific example 1 is extended from the placement position guide 24 provided on the paper stacking plate 23.
[0037]
  That is, in the specific example 1, the positions of the cam 28 and the contact portion 23a are both unchanged, but in the specific example 2, the contact piece 24a slides following the mounting position guide 24, so Only when the position guide 24 moves to a specific position, the contact piece 24a contacts the cam 28a (or cam 28b), and when the placement position guide 24 moves to other positions, the contact piece 24a and the cam 28a. (Or the cam 28b) is not in contact.That is, by moving the mounting position guide 24, the operation and non-operation of the interval expanding means can be selected.
[0038]
  Here, in this specific example, when the placement position guide 24 is slid to the position for placing the postcard horizontally, the cam 28a is provided at a position where it abuts the contact piece 24a, and the position for placing the postcard vertically. A cam 28b is provided at a position where the mounting position guide 24 contacts the contact piece 24a when the mounting position guide 24 is slid. Therefore, only when a postcard is set in the paper feed cassette 4, the cam 28 a (or cam 28 b) temporarily pushes down the paper stacking plate 23 to release the pressure contact on the paper feed roller 6 side. When other sheets are set, neither of the cams 28a and 28b functions.
[0039]
  With this configuration, a post that is relatively thick and difficult to smoothly feed paper can be fed smoothly as described in the first specific example.
[0040]
  On the other hand, in the case of normal thin paper other than the postcard size, the contact piece 24a of the placement position guide 24 does not face the cam 28, so that the outer periphery of the cam 28 protrudes beyond the paper feed roller 6 as shown in the figure. In some cases, when the cam 28 rotates to the paper side, the paper is sandwiched between the paper placement plate 23 and the cam 28. However, as described in the first specific example, the sheet is sufficiently bent, and even when the feed roller 10 starts sucking the sheet, the sheet feeding roller 6 resumes rotation while the amount of bending is extended. This will not cause any trouble. Therefore, it is possible to print and record accurately from a position where a predetermined margin is placed at the leading edge of the paper.
[0041]
  In the specific example 2, the outer periphery of the cams 28a and 28b protrudes from the paper feed roller 6, but the position on the mounting plate 23 facing the paper feed roller 6 is more than the position facing the cams 28a and 28b. Slightly higher than the above protruding amount. For example, as shown as specific example 3 in FIG. 6, the friction member 23 b is provided so as to protrude on the placement plate 23, and when the placement position guide 24 is at a position other than the postcard size, the paper P is strongly against the paper feed roller 6. The cams 28a and 28b do not push the paper P strongly. Thus, until the feed roller 10 and the pressure roller 8 feed downstream, the paper feed roller 6 maintains the pressure contact of the paper P against the contact portions of both the rollers 10 and 8, and the positioning of the leading position of the paper is further ensured. It is possible to prevent inclination and the like from occurring. The friction member 23b restrains the lowermost sheet on the placement plate 23 with a frictional force, and prevents several sheets from being fed together when the number of sheets on the placement plate 23 is small.
[0042]
  In each specific example, as shown as specific example 4 in FIG. 7, the outer periphery of the cams 28, 28 a, 28 b may be slightly smaller than the paper feed roller 6. Particularly in the specific examples 2 and 3, when the placement position guide 24 is at a position other than the postcard size, the cam does not come into contact with the paper P and the placement plate 23. 10 and the pressure roller 8 can reliably maintain the pressure contact with the contact portion between the rollers 10 and 8 by the paper feed roller 6 until the sheet is fed downstream.
[0043]
  Although specific examples of the present invention have been described above, various specific configurations of the present invention are possible in addition to the specific examples.
[0044]
  For example, in each of the specific examples, the speed of the paper feed roller 6 becomes “0” at the moment when the feed roller 10 starts to rotate. The roller 6 can be rotated at a lower speed than the feed roller.
[0045]
  In the above specific example, the paper transport device of the present invention is mounted on an ink jet printer. However, the paper transport device may be mounted on a printer employing another printing method, or a device other than a printer (for example, a facsimile device). ).
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of a main part of an ink jet printer equipped with a paper conveying device of the present invention.
FIG. 2 is a plan view of FIG. 1 viewed from the B direction.
FIG. 3 is a side view of a gear mechanism for driving a paper feed roller and the like.
FIG. 4 is an explanatory diagram illustrating a sheet feeding state by a sheet feeding roller.
FIG. 5 is a plan view corresponding to FIG. 2 in another specific example.
FIG. 6 is a front view of FIG. 5 as seen from the direction C in still another specific example.
FIG. 7 is a partially enlarged secondary sectional view corresponding to FIG. 1 in still another specific example.
[Explanation of symbols]
4 ... feed cassette, 6 ... feed roller, 8 ... pressure roller, 10 ... feed roller, 12 ... print head, 23 ... paper stacking plate, 23a ... contact 24, placement position guide, 24a ... contact piece, 25 ... spring, 28, 28a, 28b ... cam, 29 ... spacer, 45 ... sun gear, 47 ... First planetary gear, 48... Second planetary gear, 49... Intermediate gear, 50.

Claims (6)

Friction force generated between a paper stacking unit capable of stacking and stacking a large number of sheets and a position contacting the upper surface of the sheet placed on the sheet stacking unit and the rotation of the sheet. A paper feed roller that feeds the paper downstream, and a transport mechanism that abuts the leading edge of the paper fed by the paper feed roller to temporarily stop the paper and then transports the paper downstream And a leading end of the paper fed to the paper feed roller is provided in the paper stacking unit and is slidable in a direction crossing the paper feeding direction. After the contact, the sheet stacking unit and / or the sheet feeding roller is operated to temporarily increase the distance between the two, and by moving the placement position guide, Action Sheet conveying apparatus characterized by can select a non-operation. 2. The paper conveying apparatus according to claim 1, further comprising urging means for urging the paper stacking portion toward the paper feed roller, wherein the interval enlarging means includes a cam that rotates in conjunction with the paper feed roller. And the cam is configured to temporarily push back the paper stacking portion in the direction away from the paper feed roller against the biasing force of the biasing means with the cam only when the placement position guide is at a specific position. A sheet conveying device characterized by that.   3. The paper transport apparatus according to claim 2, wherein the cam is provided on the same rotation shaft as the paper feed roller. In the paper conveying device according to any one of claims 1 to 3, a pair of sun gears that are rotationally driven in either the forward or reverse direction in conjunction with the conveying mechanism, and a pair around the sun gears, First and second planetary gears that move in the forward or reverse direction around the sun gear while rotating in mesh with the sun gear, respectively, and the first planetary gear during forward rotation of the sun gear, A feed gear that meshes with the second planetary gear via an intermediate gear and rotates in the forward direction and rotates the feed roller in the forward direction while the sun gear rotates in the forward direction. When the sun gear reversely rotates prior to the conveyance by the paper, the paper is sent out to the paper feed roller and the leading edge of the paper comes into contact with the conveyance mechanism, and only when the placement position guide is at a specific position, Continue Sheet conveying apparatus wherein the distance expansion means extending the distance between the feed roller and the paper stacking portion.   5. A printer comprising the paper transport device according to claim 1, and further comprising a print head for printing on the paper downstream of the transport mechanism.   6. The printer according to claim 5, wherein the print head is an ink jet head that prints by ejecting ink droplets.

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