The present application claims priority from Japanese Patent Application No. 2007-049163, which was filed on Feb. 28, 2007, the disclosure of which is herein incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a sheet feeding device which feeds sheets from a first tray to a second tray via a sheet-feed path and in which a sheet is discharged to the second tray such that the sheet slides under another sheet that has been fed immediately before the sheet.
2. Discussion of Related Art
There has been conventionally known an image reading device, such as a copying machine or a scanner, that is equipped with an auto document feeder (hereinafter abbreviated as “ADF”). The ADF is configured to feed document sheets in a sheet-feed direction from a sheet-supplying tray on which the document sheets before being fed are stacked, to a sheet-receiving tray on which the document sheets after having been fed from the first tray are stacked. The image reading device is often equipped with a flat bed scanner (hereinafter abbreviated as “FBS”), in addition to the ADF. For instance, the ADF is provided on a document cover of the FBS. A user selectively uses the ADF and the FBS depending upon an intended operation that is to be performed. Where image reading is performed on a plurality of document sheets, for instance, the ADF is preferably used.
The ADF is often constructed to have a two-tier structure in which the sheet-supplying tray and the sheet-receiving tray are superposed on each other. Further, in the ADF, there is formed, as a sheet-fed path extending from the sheet-supplying tray to the sheet-receiving tray, a so-called U-turned path through which a document sheet is fed while being turned around. Where the sheet-supplying tray is disposed below the sheet-receiving tray, the document sheet which has been fed from the sheet-supplying tray into the sheet-feed path is turned around upward and finally discharged to the sheet-receiving tray. Accordingly, where the document sheet is placed facedown on the sheet-supplying tray, the document sheet is discharged faceup on the sheet-receiving tray.
Where the image reading is performed successively on a plurality of document sheets using the ADF, it is preferable that the order of the document sheets before the image reading be maintained the same as the order of the document sheets after the image reading. Further, it is preferable that the image reading be performed on the plurality of document sheets sequentially from an initial or first page of the document sheets. Where the plurality of document sheets are placed facedown on the sheet-supplying tray, for instance, the first-page document sheet is located at a lowermost position in the document sheets stacked on the sheet-supplying tray. In this instance, there is employed a sheet-feed system in which the document sheets stacked on the sheet-supplying tray are fed in order such that the document sheet which is located at the lowermost position in the stack of the document sheets is first separated from the stack of the document sheets and fed to the sheet-feed path.
As described above, the document sheets which have been fed through the U-turned sheet-feed path for the image reading are discharged faceup on the sheet-receiving tray. Accordingly, in order to collate the discharged document sheets such that the first-page document discharged first to the sheet-receiving tray is located at an uppermost position in the document sheets to be stacked on the sheet-receiving tray after having been discharged, the document sheets to be discharged subsequent to the first-page document sheet need to be stacked such that one document sheet slides under another document sheet that has been discharged immediately before that one document sheet. Patent Publication Document 1 (U.S. 2005/0194731 A1 corresponding to JP-A-2005-253013) and Patent Publication Document 2 (U.S. 2005/0212195 A1 corresponding to JP-A-247575) disclose a sheet feeder equipped with the ADF that realizes such a function.
In the ADF that employs the above-described sheet-feed system, the document sheets which are successively discharged to the sheet-receiving tray receive a load from the document sheets which are already stacked on the sheet-receiving tray after having been discharged. Where the weight of the document sheets stacked on the sheet-receiving tray increases with an increase in the number of the discharged and stacked sheets, for instance, friction resistance that is received by the document sheets to be subsequently discharged thereafter inevitably increases. Further, where the document sheets stacked on the sheet-receiving tray are warped in the sheet-feed direction, namely, where the discharged document sheets stacked on the sheet-receiving tray droop downwardly, the document sheets to be subsequently discharged receive a load at leading end portions thereof due to a contact with the drooped document sheets. In particular when the length of the sheet-receiving tray as measured in the sheet-feed direction is made small in an attempt to enhance the usability and the viewability of the sheet-supplying tray, the load due to the warpage or drooping of the document sheets is outstandingly increased.
The load that acts on the document sheets as described above inevitably limits a number of the document sheets that can be discharged by the ADF successively and smoothly to the sheet-receiving tray. However, it is desirable that a number of the document sheets that can be fed successively by the ADF be as large as possible. Moreover, it is desirable that the document sheets be discharged to the sheet-receiving stay with high stability, without a risk of falling off from the sheet-receiving tray and a risk of being bent.
It is therefore a first object of the invention to provide a sheet feeding device which is configured such that each of document sheets to be successively discharged to a sheet-receiving tray smoothly slides under document sheets that have been already discharged to and stacked on the sheet-receiving tray, thereby ensuring smooth discharging of the document sheets. It is a second object of the invention to provide an image reading device that comprises such a sheet feeding device.
The above-indicated first object may be attained according to a first aspect of the invention, which provides a sheet feeding device, comprising: a first tray on which sheets to be fed are stacked; a second tray which is disposed above the first tray to provide a two-tier structure and on which the sheets after having fed from the first tray are stacked; a sheet-feed path extending from the first tray to the second tray; a sheet-feed mechanism which is operable to separate one of the sheets stacked on the first tray, to feed the one of the sheets into the sheet-feed path, and to discharge the one of the sheets to the second tray such that the one of the sheets slides under another of the sheets that has been discharged immediately before the one of the sheets; and at least one sheet guide which is configured to warp the sheets discharged to the second tray, in a direction perpendicular to a sheet-feed direction in which the sheets are fed.
The above-indicated second object may be attained according to a second aspect of the invention, which provides an image reading device comprising: the sheet feeding device according to the above-indicated first aspect of the invention; and an image reading portion configured to read an image recorded on each of the sheets fed through the sheet-feed path.
In the sheet feeding device according to the above-indicated first aspect of the invention and the image reading device according to the above-indicated second aspect of the invention, the sheets stacked on the first tray are separated one by one and sequentially discharged to the second tray through the sheet-feed path, by the sheet-feed mechanism. Described in more detail, the sheet-feed mechanism is operable to separate one of the sheets stacked on the first tray, to feed the one of the sheets into the sheet-feed path, and to discharge the one of the sheets to the second tray such that the one of the sheets slides under another of the sheets that has been discharged immediately before the one of the sheets. Further, the sheet guides are configured to warp the sheets after having been fed through the sheet-feed path, in the direction perpendicular to the sheet-feed direction. According to the arrangement, each of the thus warped sheets is tough and hardly bending in the sheet-feed direction. In the thus warped state, the sheets are discharged to and stacked on the second tray.
Because the sheets which have been discharged to the second tray are warped as described above, a sheet to be subsequently discharged can smoothly slide under the sheets which have been already discharged to and stacked on the second tray. Further, the thus warped sheets on the second tray are prevented from drooping downward at leading end portions thereof that protrude from the second tray, thereby reducing a load to be applied to the feeding of the sheets that are to be discharged thereafter. Accordingly, the plurality of sheets can be smoothly discharged to the second tray, whereby the number of sheets that can be successively fed by the present sheet feeding device can be increased.
The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which:
There will be hereinafter described embodiments of the invention with reference to the drawings.
1. Outline of Image Reading Device
Referring first to
The image reading device 10 includes a document supporting base 12 and a document cover 13. The document supporting base 12 has a platen glass 14 shown in
As shown in
The CIS 16 is an image sensor of a so-called contact type configured to irradiate the document sheet with a light and to convert a reflected light from the document sheet into electric signals. The CIS 16 is mounted on the carriage 17 and held in contact with the platen glass 14. The carriage 17 is configured to be reciprocated in parallel with a lower surface of the platen glass by the moving mechanism. Where the image reading device 10 is utilized as the FBS, the CIS 16 reads an image of the document sheet placed on the platen glass 14 during a sliding movement of the carriage 17 below the platen glass 14. Where the ADF 11 of the image reading device 10 is utilized, the carriage 17 is moved to a prescribed stationary position below a sheet pressing member 31 at which the carriage 17 is kept stationary, and the image of the document sheet passing on the platen glass 14 is read by the CIS 16 that is mounted on the carriage 17 kept at the stationary position.
As shown in
2. Overall Structure of ADF
Hereinafter, the structure of the ADF 11 as the sheet feeding device according to the invention will be explained in detail. The ADF 11 is provided on the document cover 13 and includes a sheet-supplying tray 21 as a first tray, a sheet-receiving tray 22 as a second tray, a sheet-feed path 23, a sheet-feed mechanism, and sheet-discharge guides 25 each as a sheet guide.
3. Sheet-Supplying Day
As shown in
The sheet-supplying tray 21 is provided with a pair of sheet-supply guides 27, 27 as a pair of third guides which are spaced apart from each other in a depth direction of the image reading device 10 corresponding to the vertical direction in
Described more specifically, where the width of the document sheet (as measured in the direction perpendicular to the sheet-feed direction) is small, one of the sheet-supply guides 27 disposed near a front side of the image reading device 10 (i.e., a lower side in
4. Sheet-Receiving Tray
As shown in
5. Sheet-Feed Path
As shown in
The sheet-feed path 23 passes over the platen glass 14 between the pull-in chute portion 28 and the discharge chute portion 30. At a position in the sheet-feed path 23 facing the platen glass 14, the sheet-feed path 23 is open to the platen glass 14, namely, the sheet-feed path 23 is partially defined by the platen glass 14. According to the arrangement, each document sheet being fed through the sheet-feed path 23 is opposed to the platen glass 14.
In the sheet-feed path 23, the sheet pressing member 31 is provided so as to be opposed to the platen glass 14. The sheet pressing member 31 is swingable in directions toward and away from the platen glass 14 and is forced downward by elastic force of a spring not shown. The sheet pressing member 31 is normally spaced apart from the platen glass 14 by a prescribed minimum distance. In this state, the sheet pressing member 31 is located in the closest vicinity of the platen glass 14. The prescribed minimum distance between the sheet pressing member 31 and the platen glass 14 is defined by projections and the like, for instance. When received an external force, the sheet pressing member 31 is retracted upward against the elastic force of the spring. Each document sheet being fed through the sheet-feed path 23 is guided by the sheet pressing member 31 and passes through a space between the platen glass 14 and the sheet pressing member 31 that corresponds to a prescribed distance.
6. Sheet-Feed Mechanism
As shown in
The pull-in roller 34 is rotatably disposed below the pull-in chute portion 28 such that its roller surface is partially exposed into the pull-in chute portion 28. The separation roller 36 is rotatably disposed at a position distant from the pull-in roller 34 in the sheet-feed direction, such that a roller surface of the separation roller 36 is partially exposed into the pull-in chute portion 28. The pull-in roller 34 and the separation roller 36 are rotatably driven by a drive force transmitted from a motor not shown. The pull-in roller 34 and the separation roller 36 have the same diameter and are rotated at the same peripheral speed. A clutch not shown is provided in a transmission path of the drive force to the pull-in roller 34, whereby the pull-in roller 34 is freely rotatable over one circumference.
The nip member 35 is disposed so as to be opposed to the pull-in roller 34 and can come into contact with and separate from the pull-in roller 34. The nip member 35 is forced downward by elastic force of a spring not shown and makes pressing contact with the pull-in roller 34 when the document sheet is not nipped therebetween. The nip member 35 can press the document sheet onto the pull-in roller 34, so that the rotational force of the pull-in roller 34 is transmitted to the document sheet.
The nip member 37 is disposed so as to be opposed to the separation roller 36 and can come into contact with and separate from the separation roller 36. The nip member 37 is forced downward by elastic force of a spring not shown and makes pressing contact with the separation roller 36 when the document sheet is not nipped therebetween. The nip member 37 can press the document sheet onto the separation roller 36, so that the rotational force of the separation roller 36 is transmitted to the document sheet.
The document sheet contacting the pull-in roller 34 and the separation roller 36 is a sheet which is located at a lowermost position in the document sheets stacked on the sheet-supplying tray 21. The lowermost document sheet is separated by the pull-in roller 34 and the separation roller 36 from the stack of the document sheets on the sheet-supplying tray 21, and is fed into the sheet-feed path 23.
The feed roller 38 is disposed so as to be distant from the separation roller 36 in the sheet-feed direction and so as to be located on the upstream side of the position in the sheet-feed path 23 at which the sheet-feed path 23 is opposed to the platen glass 14. The feed roller 38 has an outside diameter that permits its roller surface to be exposed into both of the pull-in chute portion 28 and the discharge chute portion 30. The feed roller 38 is rotatably driven by a drive force transmitted from the motor not shown.
The pinch roller 39 is disposed below the feed roller 38. The pinch roller 39 is rotatably supported by the casing 26 with its axis elastically forced by a spring member. The pinch roller 39 makes pressing contact with the feed roller 38 when the document sheet is not nipped therebetween. When the feed roller 38 is rotated, the pinch roller 39 is also rotated in accordance with the rotation of the feed roller 38. The pinch roller 39 can press the document sheet onto the feed roller 38, so that the rotational force of the feed roller 38 is transmitted to the document sheet.
The feed roller 40 is disposed so as to be distant from the feed roller 38 in the sheet-feed direction and so as to be located on a downstream side of the position in the sheet-feed path 23 at which the sheet-feed path 23 is opposed to the platen glass 14. The feed roller 40 is rotatably driven by a drive force transmitted from the motor not shown.
The pinch roller 41 is disposed below the feed roller 40. The pinch roller 41 is rotatably supported by the casing 26 with its axis elastically forced by a spring member. The pinch roller 41 makes pressing contact with the feed roller 40 when the document sheet is not nipped therebetween. When the feed roller 40 is rotated, the pinch roller 41 is also rotated in accordance with the rotation of the feed roller 40. The pinch roller 41 can press the document sheet onto the feed roller 40, so that the rotational force of the feed roller 40 is transmitted to the document sheet.
The pinch roller 42 is disposed above the feed roller 38. The pinch roller 42 is rotatably supported by the casing 26 with its axis elastically forced by a spring member. The pinch roller 42 makes pressing contact with the feed roller 38 when the document sheet is not nipped therebetween. When the feed roller 38 is rotated, the pinch roller 42 is also rotated in accordance with the rotation of the feed roller 38. The pinch roller 42 can press the document sheet onto the feed roller 38, so that the rotational force of the feed roller 38 is transmitted to the document sheet. The document sheet is discharged to the sheet-receiving tray 22 by the feed roller 38 and the pinch roller 42.
The trailing-end supporting member 43 is disposed on the downstream side of a nip position at which the document sheet is nipped or held by the feed roller 38 and the pinch roller 42. The trailing-end supporting member 43 is formed by bending a spring steel strip. In the cross-sectional view of
The trailing-end supporting member 43 has a guide surface 44 that is an inclined surface facing the feed roller 38 and the pinch roller 42. A lower end of the guide surface 44 is located at a position lower than the nip position at which the document sheet is nipped by the feed roller 38 and the pinch roller 42. An upper end of the guide surface 44 (i.e., the apex of the triangular shape) is located at a position higher than the nip position. The guide surface 44 is inclined such that its lower end is located nearer to the nip position between the feed roller 38 and the pinch roller 42 than its upper end.
The trailing-end supporting member 43 is elastically deformable such that the upper end of the guide surface 44 moves downward. When the leading end of the document sheet nipped by the feed roller 38 and the pinch roller 42 contacts the guide surface 44, the trailing-end supporting member 43 is elastically deformed so as to be pushed downward due to the toughness of the document sheet. After the trailing end portion of the document sheet passes through the nip position between the feed roller 38 and the pinch roller 42, the trailing-end supporting member 43 returns back to its original position and pushes up the trailing end portion of the document sheet to a position higher than the nip position, whereby the trailing end portion of the document sheet is supported by the trailing-end supporting member 43 at the position. Accordingly, a leading end portion of a next document sheet that is to be subsequently discharged by the feed roller 38 and the pinch roller 42 to the sheet-receiving tray 22 is guided by the guide surface 44 and slides under the trailing end portion of the document sheet that has been discharged immediately before the above-indicated next document sheet.
7. Sheet Guides
As shown in
The first guide portions 51 formed as a pair are wall-like members standing upright from the respective tray plates 22a of the sheet-receiving tray 22 and extending along the sheet-feed direction. The first guide portions 51 are opposed to each other in the direction perpendicular to the sheet-feed direction. A height of each first guide portion 51 as measured from an upper surface of each tray plate 22a is determined depending upon the number of the document sheets that can be stacked on the sheet-receiving tray 22 and so on. The first guide portions 51 are configured such that a distance therebetween gradually becomes smaller toward the downstream side in the sheet-feed direction. Described more specifically with reference to
The distance L2 between the two first guide portions 51 at the upstream ends thereof in the sheet-feed direction is the same as the distance between the two sheet-supply guides 27. As explained above, the pair of sheet-discharge guides 25 are formed integrally with the pair of sheet-supply guides 27. Accordingly, when the distance between the sheet-supply guides 27 is changed, the first guide portions 51 are slid in mutually opposite directions perpendicular to the sheet-feed direction, together with the sheet-supply guides 27, whereby the distance L2 between the first guide portions 51 is also changed. That is, the first guide portions 51 are moved together with or interdependently with the sheet-supply guides 27, so as to be moved to and located at respective prescribed slide positions corresponding to the width of the document sheets being fed. The distance L2 between the two first guide portions 51 at the upstream ends thereof in the sheet-feed direction corresponds to the width of the document sheets being fed. Accordingly, the distance between the two first guide portions 51 gradually becomes smaller toward the downstream side in the sheet-feed direction than the width of the document sheets being fed, and becomes equal to the distance L3 at the downstream ends of the first guide portions 51.
The second guide portions 52 are projecting members that project over the respective tray plates 22a of the sheet-receiving tray 22. The second guide portions 52 are provided as a pair and opposed to each other. More specifically explained, the second guide portions 52 are opposed to each other in the direction perpendicular the sheet-feed direction. A height level of the second guide portions 52 at which the second guide portions 52 are located over the tray plates 22a is determined depending upon the number of the document sheets to be stacked on the sheet-receiving tray 22, a permissible or possible vertical movement of the widthwise opposite end portions of the document sheets, etc. In the present embodiment, the height level of the second guide portions 52 is made substantially equal to a height level of upper ends of the first guide portions 51. An amount (a dimension) by which each second guide portion 52 projects in the direction perpendicular to the sheet-feed direction is determined such that the widthwise opposite end portions of the document sheets discharged to the sheet-receiving tray 22 are prevented from getting over or moving upward beyond the respective second guide portions 52. The second guide portions 52 need not be disposed right over the sheet-receiving tray 22, but may be arranged otherwise so as to allow the widthwise opposite end portions of the document sheets to pass between the second guide portions 52 and the tray plates 22a of the sheet-receiving tray 22.
The second guide portions 52 project toward each other in the direction perpendicular to the sheet-feed direction, such that the second guide portions 52 respectively overlie the widthwise opposite end portions of an uppermost one of the document sheets discharged to the sheet-receiving tray 22. As explained above, the pair of sheet-discharge guides 25 are formed integrally with the pair of sheet-supply guides 27. Accordingly, when the distance between the sheet-supply guides 27 is changed, the second guide portions 52 of the respective sheet-discharge guides 25 are slid in mutually opposite directions perpendicular to the sheet-feed direction, together with the sheet-supply guides 27, whereby the distance between the second guide portions 52 is also changed. That is, the second guide portions 52 move together or interdependently with the sheet-supply guides 27, so as to be moved to and located at respective prescribed slide positions corresponding to the width of the document sheets being fed. Accordingly, the second guide portions 52 are capable of overlying the widthwise opposite end portions of the uppermost one of the document sheets discharged to the sheet-receiving tray 22 so as to correspond to various sizes of document sheets. Because the first guide portions 51 move together with the sheet-supply guides 27, the first guide portions 51 and the second guide portions 52 move together with the sheet-supply guides 27. In other words, the first guide portions 51 and the second guide portions 52 move together or interdependently with each other.
The second guide portions 52 disposed as described above define a space therebetween in which no elements or members, such as a part of the casing 26, are present. Accordingly, each of the document sheets ejected from the casing 26 is allowed to be warped upward in the space between the second guide members 52.
8. Sheet Feeding Operation by ADF
With reference to
When the image reading is conducted using the ADF 11, the document cover 13 is closed down over the document supporting base 12, as shown in
The document sheets G inserted into the pull-in chute portion 28 come into contact with the pull-in roller 34 and pull-in nip member 35. In this respect, the pull-in roller 34 can rotate freely over one circumference in the sheet-feed direction as described above. Accordingly, the document sheets G allow the pull-in roller 34 to rotate freely in the sheet-feed direction and the pull-in nip member 35 to retract against the elastic force of the spring, so that the document sheets G are inserted to such an extent that the leading end portions thereof come into abutting contact with the separation roller 36 and the nip member 37. Thus, the document G are set on the sheet-supplying tray 21.
Subsequently, a command to initiate the image reading is inputted to the image reading device 10. The inputting of the command is performed through a start button disposed on an operation panel of the image reading device 10, a software program executed by a computer electrically connected to the image reading device 10, for instance. The operation panel and the computer are not shown.
When the command to initiate the image reading is inputted, the motor of the image reading device 10 is driven, whereby the pull-in roller 34 and the separation roller 36 are rotated. Further, the carriage 17 is moved by the moving mechanism to a position at which the carriage 17 is opposed to the sheet pressing member 31, as shown in
The document sheet 18 fed into the sheet-feed path 23 is nipped by the feed roller 38 and the pinch roller 39 and fed farther by the rollers 38, 39. Then the document sheet 18 is guided onto the platen glass 14 by the sheet pressing member 31. While not shown in
The document sheet 18 is fed farther while the image thereof is read by the CIS 16, and is then fed in a U-turned manner so as to turn around along the curved portion 29 with the leading end portion of the document sheet 18 nipped by the feed roller 40 and the pinch roller 41 and with the trailing end portion of the document sheet 18 nipped by the feed roller 38 and the pinch roller 39. The image reading by the CIS 16 continues to be performed on the document passing over the platen glass 14 during the U-turned feeding of the document sheet 18. Subsequently, the above-indicated sensor detects the trailing end portion of the document sheet 18, and it is judged that the trailing end portion of the document sheet 18 reaches the platen glass 14 based on the rotational amount of the feed roller 38. When the trailing end portion of the document sheet 18 passes past the platen glass 14, the image reading by the CIS 16 performed on the document sheet 18 is completed.
The document sheet 18 which is fed while being nipped by the feed roller 40 and the pinch roller 41 is fed farther through the discharge chute portion 30 toward the sheet-receiving tray 22 while being nipped by the feed roller 38 and the pinch roller 42. When the leading end portion of the document sheet 18 nipped by the feed roller 38 and the pinch roller 42 comes into contact with the guide surface 44 of the trailing-end supporting member 43, the leading end portion of the document sheet 18 is guided upward along the guide surface 44 while the trailing-end supporting member 43 elastically deforms due to the toughness of the document sheet 18 and moves downward. The elastic deformation of the trailing-end supporting member 43 reduces a load that acts on the document sheet 18 being fed by the feed roller 38 and the pinch roller 42, thereby avoiding sheet jamming which would arise from contacting of the document sheet 18 with the trailing-end supporting member 43.
As shown in
The distance between the first guide portions 51 gradually becomes smaller toward the downstream ends thereof as seen in the sheet-feed direction. Therefore, the document sheet 18 which is fed with its widthwise opposite side edges being in contact with the respective first guide portions 51 tends to warp in the direction perpendicular to the sheet-feed direction. On the upstream side of the first guide portions 51 as seen in the sheet-feed direction, the second guide portions 52 overlie the corresponding widthwise opposite end portions of the document sheet 18. Accordingly, the upper surface of the document sheet 18 is in contact, at the widthwise opposite end portions thereof, with the corresponding second guide portions 52. Therefore, the second guide portions 52 prevent the widthwise opposite end portions of the document sheet 18 from lifting or floating upward beyond the second guide portions 52. Further, because no elements or members, such as a part of the casing 26, are present between the second guide portions 52, the widthwise central portion of the document sheet 18 as seen in the sheet-feed direction is allowed to move upward. Thus, the document sheet 18 warps such that its widthwise central portion is located at a higher position than its widthwise opposite end portions.
The document sheet 18 ejected from the casing 26 onto the sheet-receiving tray 22 is kept in the warped state shown in
Subsequent to the first-page document sheet 18, a second-page document sheet 19 is similarly fed from the sheet-supplying tray 21 into the sheet-feed path 23. The image of the second-page document sheet 19 is read by the CIS 16 on the platen glass 14, and the document sheet 19 is fed while being nipped by the feed roller 38 and the pinch roller 42. Since the trailing end portion of the first-page document sheet 18 is supported by the trailing-end supporting member 43 at a higher position than the nip position between the feed roller 38 and the pinch roller 42 as described above, the leading end portion of the second-page document sheet 19 is guided by the guide surface 44 of the trailing-end supporting member 43 and slides under the first-page document sheet 18. Subsequently the second-page document sheet 19 is discharged to the sheet-receiving tray 22 under the first-page document sheet 18, as shown in
Thus, the plurality of document sheets G placed facedown on the sheet-supplying tray 21 are separated one by one in order starting from the lowermost document sheet in the stack of the document sheets G. The separated sheets are sequentially fed to the sheet-receiving tray 22 through the sheet-feed path 23 and are sequentially discharged faceup onto the sheet-receiving tray 22 in the order in which the document sheets G have been stacked on the sheet-supplying tray 21. Thus, the order of the document sheets G remains unchanged before and after the feeding through the sheet-feed path 23.
The first-page document sheet 18 warped by the first guide portions 51 and the second guide portions 52 exhibits toughness, and the second-page document sheet 19 similarly warped also exhibits toughness, so that the second-page document sheet 19 smoothly slides under the first-page document sheet 18 on the sheet-receiving tray 22.
Since the warped first-page document sheet 18 exhibits toughness as described above, the first-page document sheet 18 that protrudes from the sheet-receiving tray 22 is prevented from drooping downward at its leading end portion as seen in the sheet-feed direction. If the leading end portion of the first-page document sheet 18 drooped downward, the leading end portion of the second-page document sheet 19 would abut on the drooped leading end portion of the first-page document sheet 18, thereby applying a large load with respect to the feeding of the second-page document sheet 19. The load will increase with an increase in the number of the documents G successively stacked on the sheet-receiving tray 22. In the end, an “n”-th-page document sheet Gn cannot be normally discharged due to the load, and the sheet jamming would occur.
The document sheets G warped as described above on the sheet-receiving tray 22 exhibit toughness, so that the document sheets G can be stacked on the sheet-receiving tray 22 while preventing the leading end portions thereof that protrudes from the sheet-receiving tray 22 from drooping downward, thereby making it possible to reduce the load applied to the feeding of the document sheets to be subsequently discharged. Accordingly, the arrangement allows the document sheets G to be smoothly discharged to the sheet-receiving tray 22 and increases the number of the document sheets G that can be successively fed by the ADF 11.
As described above, the first guide portions 51 and the second guide portions 52 are slidable such that the distance between the first guide portions 51 and the distance between the second guide portions 52 as measured in the direction perpendicular to the sheet-feed direction are changeable, whereby the above-described advantages can be obtained for various sizes of the document sheets G.
Further, since the first guide portions 51 and the second guide portions 52 move together with or interdependently with each other, the first guide portions 51 and the second guide portions 52 can be slid at a time to the respective prescribed slide positions corresponding to the width of the document sheets G to be fed, simply by moving either one of the first guide portions 51 and the second guide portions 52. Moreover, since the first guide portions 51 and the second guide portion 52 move together with or interdependently with the sheet-supply guides 27, the first guide portions 51, the second guide portions 52, and the sheet-supply guides 27 can be slid at a time to the respective prescribed slide positions corresponding to the width of the document sheets G to be fed, simply by moving any one of the first guide portions 51, the second guide portions 52, and the sheet-supply guides 27. Accordingly, the operability of the ADF 11 can be enhanced.
There will be next explained a second embodiment of the invention. The second embodiment differs from the illustrated first embodiment in the structure of the sheet-discharge guides. Accordingly, the second embodiment will be explained only in terms of the structure of the sheet-discharge guides with reference to
The perspective view of
As shown in
The sheet-discharge guides 61 are formed on the respective tray plates 22a of the sheet-receiving tray 22 so as to extend in the sheet-feed direction, such that each sheet-discharge guide 61 in the form of a wall stands upright from one of opposite ends of the corresponding tray plate 22a, which one end is nearer to the center side of the image reading device 80 as seen in the direction perpendicular to the sheet-feed direction. The sheet-discharge guides 61 respectively provided on one and the other of the two tray plates 22a of the sheet-receiving tray 22 are symmetric relative to each other in the direction perpendicular to the sheet-feed direction and are identical in construction with each other. Accordingly, the construction of one of the sheet-discharge guides 61 will be hereinafter given.
The sheet-discharge guide 61 has an upper surface that functions as a guide surface for guiding each of the document sheets G. The guide surface consists of an inclined portion 62 and a horizontal portion 63 which are smoothly continuous or connected to each other in the sheet-feed direction, such that the inclined portion 62 is located on more upstream in the sheet-feed direction than the horizontal portion 63.
The inclined portion 62 is inclined upward so as to have a height which gradually increases from its upstream end toward its downstream end. That is, the inclined portion 62 has a lower end at its upstream end and an upper end at its downstream end. The lower end of the inclined portion 62 is located at a lower position than the nip position of the feed roller 38 and the pinch roller 42. Accordingly, each of the document sheets G to be discharged to the sheet-receiving tray 22 while being nipped between the feed roller 38 and the pinch roller 42 comes into contact with, at the leading end portion thereof, the inclined portions 62 of the respective sheet-discharge guides 61.
The horizontal portion 63 of each sheet-discharge guide 61 has a horizontal surface which is located at the same level as the upper end of the inclined portion 62 and at a higher position than the upper surface of the sheet-receiving tray 22. A height difference between the horizontal portion 63 and the upper surface of the sheet-receiving tray 22 is determined depending upon a desired amount of warpage of the document sheets G. That is, where it is desired to warp the document sheets G to a large extent, the height difference between the horizontal portion 63 and the upper surface of the sheet-receiving tray 22 is made large.
As shown in
There will be next explained a third embodiment of the invention. The third embodiment differs from the illustrated first embodiment in the structure of the sheet-discharge guides. Accordingly, the third embodiment will be explained only in terms of the structure of the sheet-discharge guides with reference to
The perspective view of
As shown in
The sheet-discharge guides 71 are formed on the respective tray plates 22a of the sheet-receiving tray 22 so as to extend in the sheet-feed direction, such that each of the sheet-discharge guides 71 in the form of a wall stands upright from the other of the opposite ends of the corresponding tray plate 22a, which other end is remote from the center side of the image reading device 81 as seen in the direction perpendicular to the sheet-feed direction. The sheet-discharge guides 71 respectively provided on one and the other of the two tray plates 22a of the sheet-receiving tray 22 are symmetric relative to each other in the direction perpendicular to the sheet-feed direction and are identical in construction with each other. Accordingly, the construction of one of the sheet-discharge guides 71 will be hereinafter given.
The sheet-discharge guide 71 has an upper surface 72 that functions as a guide surface for guiding each of the document sheets G. The upper surface 72 is inclined upward so as to have a height which gradually increases from its upstream end toward its downstream end thereof as seen in the sheet-feed direction. That is, the upper surface 72 has a lower end at its upstream end and an upper end at its downstream end. The lower end of the upper surface 72 is continuous or connected to the upper surface of the sheet-receiving tray 22. Accordingly, each of the document sheets G to be discharged to the sheet-receiving tray 22 while being nipped between the feed roller 38 and the pinch roller 42 is picked up or scooped upward, at its leading end, by the upper surfaces 72 of the respective sheet-discharge guides 71.
As shown in
It is to be understood that the invention is not limited to the details of the illustrated embodiments, but may be embodied with various changes and modifications, which may occur to those skilled in the art, without departing from the spirit and scope of the invention defined in the attached claims.
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