Patent Publication Number: US-8523169-B2

Title: Sheet feeding apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet feeding apparatus and an image forming apparatus, particularly to a configuration of a lateral-end regulating portion which regulates a lateral-end position of a sheet stored in a sheet feeding cassette detachably attached to the sheet feeding apparatus. 
     2. Description of the Related Art 
     Nowadays, an image forming apparatus in which a sheet feeding apparatus feeds a sheet to an image forming portion to form an image is widely spread in image forming apparatuses, such as a copying machine, a printer, and a facsimile machine. As to the sheet feeding apparatus, generally a sheet feeding cassette is detachably attached to an apparatus body, and the sheet stored in the sheet feeding cassette is automatically fed to an image forming portion. 
     For example, in some of the sheet feeding cassettes used in the sheet feeding apparatus, a sheet supporting plate which presses the stacked sheet against a feeding roller is provided while being able to be lifted and lowered. A rear-end regulating portion is slidably provided in the sheet feeding cassette in which the sheet supporting plate is provided. The rear-end regulating portion regulates a position at an end (hereinafter referred to as a rear end) on an upstream side in a sheet feeding direction of the sheet stacked and stored on the sheet supporting plate such that the sheets having different sizes can be stored. A pair of lateral-end regulating portions is also provided in order to regulate a lateral-end position in a direction (hereinafter referred to as a width direction) orthogonal to the sheet feeding direction. 
     The pair of lateral-end regulating portions regulates lateral ends of the sheet, and the rear-end regulating portion regulates the rear end of the sheet, whereby the sheet is always regulated in a predetermined position. Therefore, when the sheet feeding cassette is accommodated in the apparatus body, the sheet can be fed from the fixed position irrespective of a size of the sheet. In a sheet feeding cassette of the related art, a guide projection is provided in an upper end part of a sheet abutting surface of the lateral-end regulating portion such that an end part of the sheet does not climb over the lateral-end regulating portion when the sheet is fed. 
     When the sheet is left in a low-temperature, low-humidity environment, the sheet is warped (hereinafter referred to as curled), and both end parts of the sheet rise. As illustrated in  FIG. 9A , when a sheet S is curled, a clearance K is generated between the end part of the sheet S and each of projections  42 T and  43 T, and therefore sometimes the end part of the sheet S climbs over lateral-end regulating portions  42  and  43  when feeding the sheet S. 
     When the end part of the sheet S climbs over the lateral-end regulating portions  42  and  43 , the sheet S generates a skew feeding, or the sheet S is fed while deviated in the width direction. When sheet feeding performance is degraded in this way, possibly print accuracy is degraded, or a jam is generated. Meanwhile, when projection amounts of the projections  42 T and  43 T are increased in a sheet direction, the sheet S does not climb over the lateral-end regulating portions  42  and  43 . However, the sheet S is hardly set, and possibly the projections  42 T and  43 T damage the end part of the sheet. Therefore, from the viewpoint of usability, it is not preferable that the projection amounts of the projections  42 T and  43 T be increased. 
     Conventionally, in order to solve the problem, projections  42   k  and  43   k  are rotatably provided in the lateral-end regulating portions  42  and  43  as illustrated in  FIG. 9B  (see Japanese Patent Laid-Open No. 2007-197184). When the sheet is set in the sheet feeding cassette disclosed in Japanese Patent Laid-Open No. 2007-197184, the projections  42   k  and  43   k  are rotated in direction of an arrow C about guide projection centers  42   s  and  43   s , which allows the sheet to be set without degrading the usability. 
     In the sheet feeding apparatus of the related art, it is necessary that the projections  42   k  and  43   k  be returned to climbing-over regulating positions parallel to the sheet after the projections  42   k  and  43   k  are rotated in the direction of the arrow C to set the sheet. However, as illustrated in  FIG. 9B , in order to return the projections  42   k  and  43   k  to the climbing-over regulating positions, a height of the sheet feeding apparatus is increased by a projection amount F of the guide projection, and the number of components is increased to lead to an increase in cost. 
     Therefore, the invention is aimed at a sheet feeding apparatus and an image forming apparatus, which can improve the sheet feeding performance at low cost without degrading the usability. 
     SUMMARY OF THE INVENTION 
     A sheet feeding apparatus according to an aspect of the invention, includes: a sheet feeding cassette detachably attached to an apparatus body, which stores sheets; a sheet feeding portion feeds a sheet stored in the sheet feeding cassette; a pair of lateral-end regulating portions which is provided in the cassette to regulate a lateral-end position of the sheet in a width direction orthogonal to a sheet feeding direction; a regulating portion which is projected from an abutting surface of each of the pair of lateral-end regulating portions, the abutting surface abutting on a lateral end of the sheet, the regulating portion regulating climbing over the pair of lateral-end regulating portions of the sheet when the sheet is fed; and an upper regulating portion which is provided in an inner wall surface of an attaching space, in which the sheet feeding cassette of the apparatus body is attached, and regulates the sheet when the sheet climbs over the regulating portion. 
     A sheet feeding apparatus according to another aspect of the invention in which a sheet feeding portion feeds a sheet stored in a sheet feeding cassette detachably attached to an apparatus body, the sheet feeding apparatus includes: a pair of lateral-end regulating portions which is provided in the cassette to regulate a lateral-end position of the sheet in a width direction orthogonal to a sheet feeding direction; a regulating portion which is projected to a position higher than an upper surface of the stacked sheet in an abutting surface of each of the pair of lateral-end regulating portions, the abutting surface abutting on a lateral end of the sheet; and an upper regulating portion which is projected onto the sheet feeding cassette side at a position higher than the regulating portion in an inner wall surface of an attaching space, in which the sheet feeding cassette of the apparatus body is attached. 
     According to the invention, when the sheet climbs over the lateral-end regulating portion, the upward movement of the sheet is regulated by the plural upper regulating portions, which are provided opposite each other in the inner wall surface of the attaching space. Therefore, the sheet feeding performance can be improved at low cost without degrading the usability. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a schematic configuration of a laser beam printer which is of an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the invention; 
         FIGS. 2A and 2B  are first views illustrating a configuration of the sheet feeding apparatus; 
         FIGS. 3A and 3B  are second views illustrating the configuration of the sheet feeding apparatus; 
         FIGS. 4A and 4B  are third views illustrating the configuration of the sheet feeding apparatus; 
         FIG. 5  is a view illustrating a configuration of a sheet feeding cassette attached to the sheet feeding apparatus; 
         FIGS. 6A ,  6 B, and  6 C are views illustrating a sheet feeding state of the sheet feeding cassette; 
         FIGS. 7A ,  7 B, and  7 C are views illustrating a sheet feeding state of a sheet feeding cassette according to a comparative example of the first embodiment; 
         FIGS. 8A and 8B  are views illustrating a configuration of a sheet feeding cassette attached to a sheet feeding apparatus according to a second embodiment of the invention; and 
         FIGS. 9A and 9B  are views illustrating a sheet stacking state of a sheet feeding cassette of the related art. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the drawings.  FIG. 1  is a view illustrating a schematic configuration of a laser beam printer which is of an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the invention. Referring to  FIG. 1 , in a laser beam printer  1 , a sheet feeding apparatus  1 C which feeds a sheet to an image forming portion  1 B is provided in a lower part of laser beam printer body (hereinafter referred to as an apparatus body)  1 A. 
     The image forming portion  1 B includes a cartridge unit  51 , which is provided with a photosensitive drum  50  which is of an image bearing member, and a laser beam scanner  52  which exposes the photosensitive drum  50 . During image formation, the laser beam scanner  52  exposes the photosensitive drum  50  to form a latent image in a photosensitive drum surface, and the latent image is developed to form a toner image on the photosensitive drum surface. 
     The sheet feeding apparatus  1 C includes a sheet feeding cassette  4  which is of a sheet stacking portion detachably attached to the apparatus body  1 A and a sheet feeding roller  6  which is provided above the sheet feeding cassette  4  to deliver a sheet stored in the sheet feeding cassette  4 . The sheet feeding apparatus  1 C also includes a feed roller  14  and a retard roller  15 , which constitute a separation portion to separates the sheet delivered from the sheet feeding roller  6 . 
     A sheet supporting plate  8  which presses the sheet against the sheet feeding roller side is provided in the sheet feeding cassette  4  so as to be able to be lifted and lowered. The sheet feeding cassette  4  is attached to the apparatus body  1 A, which is also used as a sheet feeding apparatus body, from a direction of an arrow A in  FIG. 3 . The sheet feeding cassette  4  is pulled out from a direction of an arrow H. 
     In the configuration of the sheet feeding apparatus  1 C, the sheet stored in the sheet feeding cassette  4  is delivered by the sheet feeding roller  6  in parallel with a toner-image forming operation of the image forming portion  1 B. The sheets are separated one by one by the feed roller  14  and the retard roller  15 . Then, pair of conveying rollers  80  the sheet to a pair of registration rollers  82 , and the pair of registration rollers  82  conveys the sheet to a transfer portion, which is formed by the photosensitive drum  50  and a transfer roller  83 , in predetermined timing. 
     The toner image formed on the photosensitive drum surface is transferred to the sheet conveyed to the transfer portion. Then the sheet is conveyed to a fixing device  84 , and the sheet is heated and pressurized by the fixing device  84 , thereby fixing the toner image. After the toner image is fixed, a pair of discharge rollers  85  discharges the sheet to a discharge portion  86  to a top surface of the apparatus body. 
     On the other hand, when the image is also formed on a second surface, after the sheet in which the image is already formed on one side passes through the fixing device  84 , a pair of reverse rollers  87  performs switchback conveyance of the sheet, the sheet passes through a both-sided unit  110 , and the pair of registration rollers  82  conveys the sheet to the transfer portion again. The image is formed on the opposite-side surface by the transfer portion, and then the sheet is discharged to the discharge portion  86 . 
     As illustrated in  FIG. 2A , the sheet feeding apparatus  1 C includes the sheet feeding roller  6 , the feed roller  14 , and the retard roller  15 , which constitute the sheet feeding portion. A sheet supporting plate  8 , which is of the sheet stacking portion on which the sheet is stacked, is provided in the sheet feeding cassette  4  while being vertically rotatable. When the sheet is fed, the sheet supporting plate  8  rotates upward to be lifted to a feeding position in which the sheet can be fed. 
     A rear end regulating portion  44  is slidably provided in the sheet feeding cassette  4 . The rear end regulating portion  44  regulates a rear-end position of the sheet stacked and stored on the sheet supporting plate  8  such that the sheets having different sizes can be stored. A pair of lateral-end regulating portions  42  and  43  is provided opposite each other, and the lateral-end regulating portions  42  and  43  regulate a lateral-end position of the sheet in a width direction orthogonal to a sheet feeding direction. As illustrated in  FIG. 2B , the lateral-end regulating portions  42  and  43  include rack portions  42   a  and  43   a . The lateral-end regulating portions  42  and  43  are formed by molding plastic. 
     The lateral-end regulating portions  42  and  43  are configured to simultaneously move by the same amount in the width direction around a pinion gear  33  using the rack portions  42   a  and  43   a  and the pinion gear  33  provided in a bottom of the sheet feeding cassette  4 . As illustrated in  FIG. 9  described in the related art, projections  42 T and  43 T which are of a regulating portion are provided opposite each other on sheet abutting surfaces of the lateral-end regulating portions  42  and  43 . In feeding the sheet, the projections  42 T and  43 T regulate climbing over the lateral-end regulating portions  42  and  43  of an end part of the sheet. The sheet feeding apparatus of the first embodiment is a guide-center device, in which the sheet is delivered while a center of the sheet in the width direction orthogonal to the sheet feeding direction is aligned with a center of a sheet conveying path in the width direction in the image forming apparatus. Therefore, as described above, the lateral-end regulating portions  42  and  43  contact with and separate from each other by the same moving amount such that the center of the sheet in the width direction is located in the same position even in the sheets having different sizes. 
     In the first embodiment, the both-sided unit  110  is detachably attached to the apparatus body  1 A.  FIG. 3A  illustrates a state before the both-sided unit  110  is attached to the apparatus body  1 A, and  FIG. 3B  illustrates a state in which the both-sided unit  110  is attached to the apparatus body  1 A. 
     As illustrated in  FIG. 4 , guide members  100  and  101  are provided opposite each other along a cassette attaching direction in inner wall surfaces of opposite frames  102  and  103  of the apparatus body  1 A such that the both-sided unit  110  can detachably be attached. The both-sided unit  110  is guided by the guide members  100  and  101 , and attached to the apparatus body  1 A.  FIG. 4A  illustrates a state in which the sheet feeding cassette  4  is attached to the apparatus body  1 A, and  FIG. 4B  illustrates a state when the sheet feeding cassette  4  is pulled out from the apparatus body  1 A. An attaching space G in which the sheet feeding cassette  4  is detachably attached is formed by the frames  102  and  103 . The frames  102  and  103  and guide members  100  and  101  of the apparatus body  1 A are formed by molding plastic. 
     As illustrated in  FIG. 3B , when the both-sided unit  110  is attached to the apparatus body  1 A, a height-direction clearance Q between the both-sided unit  110  and the lateral-end regulating portions  42  and  43  ranges from about 1 mm to 5 mm. Because a height of the apparatus body is increased with increasing clearance Q, preferably the clearance Q is small. 
     As illustrated in  FIGS. 3A and 4 , first and second guide projections  100   a  and  100   c  which are of an upper regulating portion are integrally provided in the guide member  100 . The guide projections  100   a  and  100   c  abut on the sheet to regulate the upward movement of the sheet when the sheet climbs over the projections  42 T and  43 T. Although not illustrated, the same guide projections are also provided in the guide member  101 . 
     In the guide projections  100   a  and  100   c , the first guide projection  100   a  on a downstream side in the sheet feeding direction is located in a position higher than the projection  42 T, which is provided in the lateral-end regulating portion  42 , by a distance Y 2 . The second guide projection  100   c  on an upstream side in the sheet feeding direction is located in a position higher than the projection  42 T by a distance Y 1 . A relationship of Y 1 &lt;Y 2  holds in the distances Y 1  and Y 2 . That is, in the plural (in the first embodiment, two) guide projections  100   a  and  100   c , which are provided opposite the guide members  100  and  101  provided along the cassette attaching direction, the first guide projection  100   a  is provided above the second guide projection  100   c.    
     As described above, in a case that the projection  42 T is provided on the lateral-end regulating portion  42  of the sheet feeding cassette  4 , the increased overlapping amount of the projection  42 T largely degrades the usability when a user stores the sheets in the sheet feeding cassette. Therefore, in the first embodiment, the overlapping amount of the projection  42 T of the lateral-end regulating portion  42  with the upper surface of the sheet is set within a proper range of about 1 mm to 5 mm such that the sheets can easily be set without damaging the end part of the sheet. 
     The first and second guide projections  100   a  and  100   c  are provided in the guide member  100  so as to overlap with the upper surface of the sheet. The overlapping amounts of the first and second guide projections  100   a  and  100   c  are properly set, whereby the upward movement of the sheet can be regulated even if the sheet climbs over (the projections  42 T and  43 T of) the lateral-end regulating portions  42  and  43 . In other words, the upper surface of the sheet can be regulated by properly setting the overlapping amounts of the first and second guide projections  100   a  and  100   c.    
     As illustrated in  FIG. 5 , the lateral-end regulating portion  42  includes a position regulating surface  42 H which abuts on a lateral end in the width direction of the sheet to regulate the position in the width direction of the sheet. The guide member  100  includes a first position regulating portion  100   b  which is located below the first guide projection  100   a  to regulate the position in the width direction of the sheet and a second position regulating portion  100   d  which is located below the second guide projection  100   c  to regulate the position in the width direction of the sheet. 
     The first and second position regulating portions  100   b  and  100   d  are provided, whereby the movement in the width direction of the sheet is regulated by the first and second position regulating portions  100   b  and  100   d  when the sheet climbs over the projection  42 T of the lateral-end regulating portion  42 . In order to regulate the movement in the width direction of the sheet, the first and second position regulating portions  100   b  and  100   d  are located close to the position regulating surface  42 H of the lateral-end regulating portion  42  in the sheet feeding direction while located flush with or slightly outside the position regulating surface  42 H in the width direction. Therefore, when the sheet is lifted or fed, or when the sheet climbs over the projection  42 T, the sheet can smoothly be conveyed from the position regulating surface  42 H to the first and second position regulating portions  100   b  and  100   d  while the end part of the sheet is not hung up. 
     As illustrated in  FIG. 9A , sometimes sheets S set in the sheet feeding cassette  4  become the curl state in which the end part of the sheet is warped in a low-temperature, low-humidity environment. Particularly, the curl is easily generated in a thin sheet, and the curl is also observed in a standard-size sheet, such as a LTR-size sheet and an A4-size sheet, because various types having different thicknesses are sold. On the other hand, in the first embodiment, the first and second guide projections  100   a  and  100   c  are provided in the guide member  100 , which allows a climbing-over amount to be regulated even if the sheet climbs over the lateral-end regulating portions  42  and  43 . 
     The sheet feeding cassette  4  having the above configuration in the sheet feeding state will be described below with reference to  FIG. 6 . When the sheet feeding cassette  4  is in the sheet feeding state, the sheet supporting plate  8  is lifted to a sheet surface detection level in a direction of an arrow B as illustrated in  FIG. 6A . As described above, the first guide projection  100   a  on the downstream side is provided in the position higher than the second guide projection  100   c  on the upstream side. 
     Therefore, a difference between a distance L from the upper surface of the lifted sheet S to the first guide projection  100   a  and a distance M from the upper surface to the second guide projection  100   c  is small. That is, when the sheet supporting plate  8  is lifted, the distances L and M from the upper surface of the sheet S to the first and second guide projections  100   a  and  100   c  become substantially equal to each other. In other words, when the sheet supporting plate  8  is lifted, gaps between the sheet supporting plate  8  and the first and second guide projections  100   a  and  100   c  become substantially equal to each other. 
       FIG. 6B  is a sectional view taken on a line v-v of  FIG. 6A , and  FIG. 6B  illustrates the state in which the end part of the sheet S climbs over the projection  42 T of the lateral-end regulating portion  42  when the curled sheet S is fed. In this case, the end part of the sheet S is regulated by a base  100 E of the first guide projection  100   a . At this point, the sheet S shifts in the width direction, and a shift amount of the sheet S becomes a distance F 1  from the lateral-end regulating portion  43  on the opposite side to the end part of the sheet. 
       FIG. 6C  is a sectional view taken on a line w-w of  FIG. 6A . When the end part of the curled sheet S climbs over the projection  42 T of the lateral-end regulating portion  42 , the end part of the sheet S is regulated by a base  100 F of the second guide projection  100   c . At this point, the sheet S shifts in the width direction, and the shift amount of the sheet S becomes a distance R 1  from the lateral-end regulating portion  43  on the opposite side to the end part of the sheet. 
     As described above, the heights of the upper surface of the sheet S and the first and second guide projections  100   a  and  100   c  are set such that the distances L and M from the upper surface of the sheet to the first and second guide projections  100   a  and  100   c  become substantially equal to each other when the sheet supporting plate  8  is lifted. Therefore, a difference between the distances F 1  and R 1  from the lateral-end regulating portion  43  on the opposite side to the end part of the sheet is small. As a result, the shift amounts are equalized at the leading end and the rear end of the sheet, so that a skew feeding amount of the sheet can be suppressed to a small level in feeding the sheet. 
       FIG. 7  illustrates a comparative example of the first embodiment. In the comparative example, as illustrated in  FIG. 7A , a second guide projection  100   e  on the upstream side is set to the same height as the first guide projection  100   a . In this case, as illustrated in  FIG. 7B  which is of the sectional view taken on the line v-v of  FIG. 7A , when the end part of the sheet S climbs over the projection  42 T of the lateral-end regulating portion  42 , the sheet S shifts in the width direction, and the shift amount of the sheet S becomes the distance F 1  from the lateral-end regulating portion  43  on the opposite side to the end part of the sheet. 
     On the other hand, as illustrated in  FIG. 7C  which is of the sectional view taken on the line w-w of  FIG. 7A , when the end part of the curled sheet S climbs over the projection  42 T of the lateral-end regulating portion  42 , the sheet S shifts in the width direction, and the shift amount of the sheet S becomes a distance R 2  from the lateral-end regulating portion  43  on the opposite side to the end part of the sheet. At this point, the distance R 2  becomes larger than the distance R 1  in  FIG. 6C  to generate a difference between the shift amount at the leading end and the rear end of the sheet, which increases the skew feeding amount in feeding the sheet. 
     As described above, the skew feeding amount is increased in feeding the sheet when the second guide projection  100   e  is set to the same height as the first guide projection  100   a  on the downstream side. Therefore, in order to decrease the skew feeding amount, it is necessary that the second guide projection  100   c  be set to a position lower than the first guide projection  100   a  on the downstream side. That is, the skew feeding amount can be decreased by setting the second guide projection  100   c  to a position lower than the first guide projection  100   a  on the downstream side. 
     As described above, in the first embodiment, when the sheet is fed, the skew feeding amount can be decreased by providing the guide projections  100   a  and  100   c  in the guide members  100  and  101 . Therefore, the good print accuracy can be obtained and the jam caused by the skew feeding can be reduced. The overlapping amounts of the projections  42 T and  43 T can be decreased by providing the guide projections  100   a  and  100   c  in the guide members  100  and  101 , and the projections  42 T and  43 T can be prevented from interrupting the storage of the sheet. Therefore, a profile of the apparatus body  1 A can be suppressed without degrading the usability. Additionally cost reduction can be achieved because the projections  42 T and  43 T are formed integrally with the guide members  100  and  101 . 
     That is, when the sheet climbs over the lateral-end regulating portions  42  and  43 , the upward movement of the sheet is regulated by the guide projections  100   a  and  100   c  provided in the guide members  100  and  101 , so that the sheet feeding performance can be improved at low cost without degrading the usability. 
     A second embodiment of the invention will be described below.  FIG. 8  is a view illustrating a configuration of a sheet feeding cassette of a sheet feeding apparatus according to the second embodiment. In  FIG. 8 , the part identical or equivalent to that in  FIG. 4  is designated by the identical numerals.  FIG. 8A  illustrates a state in which the sheet S is curled in the sheet feeding cassette, and  FIG. 8B  illustrated a state in which the sheet S is not curled. 
     As illustrated in  FIG. 8 , the lateral-end regulating portions  42  and  43  include the position regulating surfaces  42 H and  43 H. The guide member  100  includes the guide projections  100   a  and  100   c . The guide member  100  also includes the position regulating portions  100   b  and  100   d  which are of the guide portion. The guide member  100  is provided below the guide projections  100   a  and  100   c , and the position regulating portions  100   b  and  100   d  regulate the position in the width direction of the sheet while orienting the sheet, which climbs over the projection  42 T, toward the guide projections  100   a  and  100   c.    
     The guide member  101  which is provided opposite the guide member  100  includes the guide projection  101   a  and  101   c . The guide member  101  also includes the position regulating portions  101   b  and  101   d . The guide member  100  is provided below the guide projections  101   a  and  101   c , and the position regulating portions  101   b  and  101   d  regulate the position in the width direction of the sheet while orienting the sheet, which climbs over the projection  43 T, toward the guide projections  101   a  and  101   c.    
     In the second embodiment, the position regulating portions  100   b  and  100   d  of the guide member  100  and the position regulating portions  101   b  and  101   d  of the guide member  101  are projected inward from the positions in  FIG. 5 . That is, the position regulating portions  101   b  and  101   d  of the guide member  101  are disposed inside by a distance N 1  in the width direction with respect to the position regulating surface  43 H of the lateral-end regulating portion  43 . The position regulating portions  100   b  and  100   d  of the guide member  100  are also disposed inside by the distance N 1  in the width direction with respect to the position regulating surface  42 H of the lateral-end regulating portion  42 . That is, the position regulating portions  100   b ,  100   d ,  101   b , and  101   d  are projected toward the upward direction of the sheet with respect to the position regulating surfaces  42 H and  43 H. 
     For example, when the sheet S is left in the low-temperature, low-humidity environment, the end part of the sheet S is curled, the sheet S is warped from the state in  FIG. 8B  to the state in  FIG. 8A , and the sheet S off-sets inward by the distance N 1  on both the sides in the width direction. When the guide projections  100   a ,  100   c ,  101   a , and  101   c  are not provided, the curled sheet S is regulated in the positions corresponding to the position regulating surfaces  42 H and  43 H. At this point, when the sheet S is fed, a margin at the left or right end of the sheet S shifts by the distance N 1 , or a clearance for the distance N 1  is generated between both the end of the sheet and the position regulating portions. Therefore, the skew feeding is easily generated. 
     On the other hand, in the second embodiment, the position regulating portions  101   b  and  101   d  of the guide member  101  and the position regulating portions  100   b  and  100   d  of the guide member  100  are disposed inward by the distance N 1  in the width direction. Therefore, when the sheet climbs over the lateral-end regulating portions  42  and  43 , the sheet moves toward the guide projections  100   a ,  100   c ,  101   a , and  101   c  while being guided by the position regulating portions  100   b ,  100   d ,  101   b , and  101   d . Then the upward movement of the sheet is regulated by the guide projections  100   a ,  100   c ,  101   a , and  101   c . Therefore, the sheet feeding performance can be improved at low cost without degrading the usability. 
     As described above, in the second embodiment, the position regulating portions  100   b ,  100   d ,  101   b , and  101   d  are projected inward by the distance N 1  in the width direction with respect to the position regulating surfaces  42 H and  43 H. Therefore, when the curled sheet S climbs over the projection  42 T and  43 T of the lateral-end regulating portions  42  and  43 , the sheet S can securely be oriented toward the guide projections  100   a ,  100   c ,  101   a , and  101   c . Accordingly, the upward movement of the sheet S can securely be regulated, and the print accuracy of the margin of the sheet S can be improved, and a possibility of the jam caused by the skew feeding can be reduced. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2011-172872, filed Aug. 8, 2011, which is hereby incorporated by reference herein in its entirety.