Sheet feeding unit and printer

A sheet feeding unit to be inserted between a printer main unit and a sorting unit having a plurality of discharge trays. The sheet feeding unit includes a casing in which a sheet is housed and through which a feed path and a discharge conveyance path extend horizontally. The casing has on a face thereof adjacent to the printer main unit an exit of the feed path and an entrance of the discharge conveyance path, and on a face thereof adjacent to the sorting unit an entrance of the feed path and an exit of the discharge conveyance path. The positions of the exit and entrance of the feed path coincide with each other when seen in a conveyance direction, and the positions of the entrance and exit of the discharge conveyance path coincide with each other when seen in the conveyance direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet feeding unit and a printer.

2. Description of the Related Art

In general, to perform printing on sheets of different sizes, sheet feeders provided for feeding the sheets of respective sizes are necessary. In addition, since such sheets that have undergone printing are usually sorted by size or intended use and are output to different discharge trays, a sorter having a number of discharge trays is used.

In Japanese Patent Laid-Open No. 5-4773, although a sheet feeder is not shown in drawings provided therein, a printer main body (an image forming apparatus) that performs printing and the like and a sorter that sorts printed sheets and discharges the sheets to discharge trays are provided as units that are connectable to each other.

In Japanese Patent Laid-Open No. 9-301623, two sorters provided as units are connected to a printer main body (an image forming apparatus) that performs printing and the like.

Although Japanese Patents Laid-Open No. 5-4773 and No. 9-301623 each disclose a sorter that sorts printed sheets into a plurality of groups and discharges the sorted sheets, the disclosures each do not include a configuration for feeding sheets of a plurality of kinds. Actually, even if it is desired to handle sheets of more kinds in one printer, there have been no proposals concerning a feeder that meets such a desire.

SUMMARY OF THE INVENTION

The present invention provides a sheet feeding unit used when sheets of more kinds are to be handled and a printer including the sheet feeding unit.

According to a first aspect of the present invention, a sheet feeding unit is to be inserted between a printer main unit configured to perform printing on a sheet and a sorting unit having a plurality of discharge trays to which the sheet that has undergone printing is to be discharged. The sheet feeding unit is connectable to the printer main unit, the sorting unit, and another sheet feeding unit. The sheet feeding unit includes a casing in which the sheet, as a recording medium, is housed and through which a feed path and a discharge conveyance path extend horizontally, the feed path being configured to feed the sheet to the printer main unit, the discharge conveyance path being configured to convey the sheet that has undergone printing performed by the printer main unit to the sorting unit. The casing has on a face thereof adjacent to the printer main unit an exit of the feed path and an entrance of the discharge conveyance path, and on a face thereof adjacent to the sorting unit an entrance of the feed path and an exit of the discharge conveyance path. The positions of the exit and entrance of the feed path coincide with each other when seen in a conveyance direction in which the sheet is conveyed, and the positions of the entrance and exit of the discharge conveyance path coincide with each other when seen in the conveyance direction.

According to a second aspect of the present invention, a printer includes a printer main unit, a sorting unit, and at least one sheet feeding unit according to the first aspect of the present invention provided between the printer main unit and the sorting unit. The positions of the entrance and exit of the feed path of the sheet feeding unit and an entrance of the printer main unit from which the sheet enters coincide with one another when seen in the conveyance direction. The positions of the entrance and exit of the discharge conveyance path of the sheet feeding unit, an exit of the printer main unit from which the sheet exits, and an entrance of the sorting unit from which the sheet enters coincide with one another when seen in the conveyance direction.

According to the above aspects of the present invention, the number of kinds of sheets, as recording media, to be handled can be easily increased arbitrarily, and good operability in feeding and discharging such sheets is realized.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will now be described with reference to the attached drawings. The following embodiment concerns an inkjet printer. The printer is a high-speed line printer capable of performing both simplex printing and duplex printing on a continuous form of paper, synthetic resin, or the like that is wound in a roll. The printer cuts the continuous form that has undergone printing into sheets of specific sizes and discharges the sheets. The printer is particularly suitable for bulk printing performed in printing laboratories and the like.

FIG. 1is a schematic diagram showing the internal configuration of the printer. The basic configuration of the printer will first be described.

The printer basically includes the following devices provided along a conveyance path shown by the solid lines. Devices responsible for feeding of a continuous form, performance of printing on the continuous form, and cutting of the continuous form into sheets include a form feeding section1, a decurling section (curl reducing section)2, a skew correcting section3, a printing section4, an inspecting section5, and a cutting section6. Devices responsible for conveyance, sorting, and discharging of the cut sheets include an information recording section7, a drying section8, a form winding section9, a discharge-conveyance section10, and a sorting section (sorting unit)11. The printer further includes a control section13that controls the operations of the foregoing devices included in the printer. The printer has a printer main unit20including the form feeding section1, the decurling section2, the skew correcting section3, the printing section4, the inspecting section5, the cutting section6, the information recording section7, the drying section8, the form winding section9, the discharge-conveyance section10, and the control section13. The sorting section11, i.e., the sorting unit, is connected to the printer main unit20. The term “unit” used herein denotes an apparatus whose mechanisms performing specific processing operations are housed in a casing and is operable as a stand-alone apparatus. Such units are connectable to each other.

The sorting unit11has a group of trays. In the embodiment, the group of trays includes, for example, large-sized-sheet discharge trays12and18, small-sized-sheet discharge trays17, and an unnecessary-sheet discharge tray19, the trays being used selectively. One of the large-sized-sheet discharge trays12and18that has the largest capacity is referred to as a large-sized-sheet bulk discharge tray18.

Most of the devices of the printer include conveying mechanisms including pairs of rollers and belts. The continuous form (or the sheet) is conveyed along the conveyance path by the conveying mechanisms and undergoes processing operations performed by the devices.

The form feeding section1houses a continuous form that is wound in a roll and feeds the continuous form. In the embodiment, the form feeding section1can house two continuous-form rolls R1and R2. The form feeding section1unwinds a continuous form from either of the rolls R1and R2and feeds the continuous form to the device provided on the downstream side. The number of continuous-form rolls that can be housed in the form feeding section1is not limited to two. The form feeding section1may house only a single roll, or three or more rolls.

The decurling section2reduces a curl of the continuous form fed from the form feeding section1. The decurling section2includes one driving roller and two pinch rollers provided on both sides of and in contact with the driving roller. The continuous form fed to the decurling section2passes through the nip between the driving roller and either of the pinch rollers and is squeezed such that the form is bent in the direction opposite to the direction of the curl thereof produced by having been wound in a roll, whereby the curl is reduced. Which of the two pinch rollers is to be used depends on the direction of the curl.

The skew correcting section3corrects any skew of the continuous form (a phenomenon that the continuous form advances while deviating from the initial position) that has passed through the decurling section2. One of the sides of the continuous form that is defined as the reference side is pressed against a guide member (not shown), whereby the skew of the sheet is corrected.

The printing section4performs printing (forms an image) on the continuous form that is being conveyed. The printing section4includes a plurality of print heads14arranged parallel to each other and side by side in a conveyance direction, and a plurality of conveying rollers that convey the continuous form. The print heads14, with which printing is performed, are line print heads each having rows of inkjet nozzles provided in such a manner as to cover the width of the largest continuous form among various kinds of continuous forms to be used. In the embodiment, seven print heads14for seven colors of cyan (C), magenta (M), yellow (Y), light cyan (LC), light magenta (LM), gray (G), and black (K) are provided. The numbers of colors and print heads14are each not limited to seven. Moreover, any of various inkjet methods may be employed, such as those employing heater devices, piezo devices, electrostatic devices, microelectromechanical systems (MEMS), and the like. Inks for the foregoing colors are supplied from ink tanks (not shown) through ink tubes to the print heads14.

The inspecting section5includes an optical device and inspects the condition of the nozzles of the print heads14, the state of conveyance, the image position, and so forth by optically reading an inspection pattern and/or an image formed on the continuous form by the printing section4.

The cutting section6includes a mechanical cutter and cuts the continuous form that has undergone printing into sheets of specific lengths. The cutting section6also includes a plurality of conveying rollers that convey the cut sheets toward the downstream side.

The information recording section7includes a printing mechanism and records printing information such as the serial number and the date on the back side (non-printed side) of each cut sheet. The printing mechanism of the information recording section7may be the same as the print head14of the printing section4, or may be smaller and simpler than the print head14. The printing mechanism is not limited to an inkjet mechanism and may be a mechanism that operates in a simpler manner. In duplex printing, the information recording section7does not operate, as described separately below.

The drying section8includes a dryer and heats the sheet (or the continuous form in duplex printing) that have undergone printing performed by the printing section4, thereby quickly drying the ink on the sheet. The drying section8also includes a conveying belt and conveying rollers that convey the sheet toward the downstream side.

In duplex printing, the continuous form that has undergone front-side printing is temporarily wound up by the form winding section9. The form winding section9includes a rotatable winding drum around which the continuous form is wound. In duplex printing, after front-side printing is finished, the continuous form is conveyed without being cut and is temporarily wound around the winding drum in the form winding section9. When the entirety of the continuous form has been wound up, the winding drum rotates in the reverse direction, whereby the continuous form that has been wound is fed into the decurling section2and is conveyed to the printing section4(the conveyance path in this case is shown by the broken line). Since the front and back sides of the continuous form that has been unwound from the winding drum are reversed, the printing section4can perform printing on the back side of the continuous form. More specific operations performed in duplex printing will be described separately below.

The discharge-conveyance section10basically includes pairs of rollers. The discharge-conveyance section10conveys each cut sheet obtained by the cutting section6and dried by the drying section8(in duplex printing, each sheet obtained after back-side printing, cutting, and drying), and delivers the sheet to the sorting unit11. In the embodiment of the present invention, the discharge-conveyance section10is provided below the form feeding section1.

The sorting unit11, i.e., the sorting section, sorts printed sheets according to need and discharges the sheets. In the embodiment, a group of trays including the large-sized-sheet discharge trays12, the small-sized-sheet discharge trays17, the large-sized-sheet bulk discharge tray18, and the unnecessary-sheet discharge tray19are selectively used. The sheets are sorted by the sorting unit11and are discharged to corresponding ones of the discharge trays. The large-sized-sheet discharge trays12and18are provided on the upstream side in the conveyance direction in the sorting unit11, i.e., on a side face of the printer. Among the large-sized-sheet discharge trays12and18, the large-sized-sheet bulk discharge tray18has the largest capacity and is distinguished from the other large-sized-sheet discharge trays12in the drawings. The small-sized-sheet discharge trays17are provided on the downstream side, i.e., on the top face of the printer. The unnecessary-sheet discharge tray19is provided on the upstream side in the conveyance direction in the sorting unit11with respect to the large-sized-sheet discharge trays12and the large-sized-sheet bulk discharge tray18, i.e., at the lowermost position on the side face of the printer. The technical significance of such an arrangement of the discharge trays12,17,18, and19will be described separately below.

The control section13controls the devices included in the printer. The control section13includes a controller15and a power supply (not shown). The controller15includes a central processing unit (CPU), a memory, and input/output (I/O) interfaces. An external apparatus16such as a host computer or the like is connected to the controller15via an I/O interface. The operation of the printer is controlled on the basis of instructions from the controller15or the external apparatus16.

A basic printing operation performed by the printer will now be described. Simplex printing and duplex printing that are performed in different manners will be described individually.

FIG. 2is a diagram for describing the operation performed in simplex printing. A continuous form is fed from the form feeding section1, the curl of the continuous form is reduced by the decurling section2, any skew of the continuous form is corrected by the skew correcting section3, and printing is performed on the front side of the continuous form by the printing section4. The continuous form that has undergone printing is inspected by the inspecting section5, and is cut into sheets of preset lengths by the cutting section6. The control section13controls the printing section4and the cutting section6such that portions of the continuous form that are to be cut out by the cutting section6substantially correspond to printing areas, respectively, of the continuous form in which individual images are printed by the printing section4. According to need, the information recording section7records printing information on the back side of each of the cut sheets obtained in such a manner, and the cut sheet is conveyed to the drying section8so as to be dried. Subsequently, the cut sheet is conveyed through the discharge-conveyance section10provided below the form feeding section1to the sorting unit11. The sorting unit11performs sorting under the control of the control section13. Specifically, cut sheets are sorted in accordance with the sizes thereof, and sheets of large sizes are discharged to the large-sized-sheet discharge trays12, and sheets of small sizes are discharged to the small-sized-sheet discharge trays17. When it is known that a large number of large-sized sheets are to be produced, the sheets are discharged to the large-sized-sheet bulk discharge tray18having the largest capacity among the large-sized-sheet discharge trays. Unnecessary sheets, such as those for test print, those having print failure, and portions corresponding to margins provided between necessary portions, are discharged to the unnecessary-sheet discharge tray19. The method of sorting performed by the sorting unit11and the method of selectively discharging sorted sheets to the discharge trays may be any of known methods, and the description thereof is omitted. What kind of sorting is to be performed by the sorting unit11is to be determined appropriately. The embodiment of the present invention is also applicable to a case where trays to which sheets are to be discharged are sequentially changed simply in accordance with the number of sheets discharged.

FIG. 3is a diagram for describing the operation performed in duplex printing. In duplex printing, a front-side printing sequence is performed first, and a back-side printing sequence is subsequently performed. In the front-side printing sequence, individual operations performed by the form feeding section1, the decurling section2, the skew correcting section3, the printing section4, and the inspecting section5are the same as those in simplex printing. At this point, cutting of the continuous form by the cutting section6and recording by the information recording section7are not performed, and the continuous form just passes through the cutting section6and the information recording section7and is conveyed to the drying section8, where ink on the front side of the continuous form is dried. Subsequently, the continuous form is introduced into a path extending to the form winding section9, not into the path extending to the discharge-conveyance section10. The continuous form that has been introduced into the path extending to the form winding section9is wound around the winding drum of the form winding section9that rotates in the forward direction (the counterclockwise direction inFIG. 3). The conveyance paths provided after the drying section8are switched therebetween by a known method in which a guide member or the like (not shown) is used.

When predetermined printing on the front side of the continuous form is finished by the printing section4, the continuous form is cut at the trailing end of the entire printed portion thereof by the cutting section6. The portion of the continuous form that is on the downstream side in the conveyance direction with respect to the cut position (the portion of the continuous form that has undergone front-side printing) is dried by the drying section8and is wound up to the trailing end (the cut end) thereof by the form winding section9. Meanwhile, the portion of the continuous form that is on the upstream side in the conveyance direction with respect to the cut position (the portion of the continuous form that has not undergone front-side printing) is rewound to the form feeding section1such that no portion of the continuous form is left in the decurling section2and other sections.

After the front-side printing sequence described above, the operation proceeds to the back-side printing sequence. Specifically, the winding drum of the form winding section9around which the continuous form has been wound up to the trailing end thereof is rotated in the backward direction (the clockwise direction inFIG. 3), i.e., the direction opposite to that in which the continuous form has been wound up. Thus, the end of the wound continuous form (the trailing end at the time of winding becomes the leading end at the time of refeeding) is fed into the decurling section2. The conveyance path valid in this operation is shown by the broken line inFIG. 3. In the decurling section2, curl correction is performed in the direction opposite to the direction of curl correction performed when the continuous form is fed from the form feeding section1. This is because the continuous form is wound around the winding drum with the front and back sides thereof reversed from those when housed in the form feeding section1and is curled in the opposite direction. The continuous form (the continuous form that has undergone front-side printing) whose curl is reduced by the decurling section2has any skew thereof corrected by the skew correcting section3and is conveyed to the printing section4again. The print heads14of the printing section4perform printing on the back side of the continuous form. The continuous form that has undergone back-side printing is inspected by the inspecting section5and is cut into sheets of preset lengths by the cutting section6. The cut sheets obtained in such a manner each have images printed on the front and back sides thereof. Therefore, recording by the information recording section7is not performed. The cut sheets are each conveyed to the drying section8so as to be dried. Subsequently, each of the sheets is conveyed through the discharge-conveyance section10provided below the form feeding section1to the sorting unit11. The sorting unit11sorts the sheets under the control of the control section13, as in the front-side printing sequence. Specifically, sheets of large sizes are discharged to the large-sized-sheet discharge trays12(or the large-sized-sheet bulk discharge tray18if a large number of sheets are to be discharged), sheets of small sizes are discharged to the small-sized-sheet discharge trays17, and unnecessary sheets are discharged to the unnecessary-sheet discharge tray19.

As described above, the printer shown inFIG. 1includes the sorting unit11and the printer main unit20that are connected to each other. Hence, the exit of the discharge-conveyance section10and the entrance of the sorting unit11are configured such that the sheet is smoothly conveyed from the discharge-conveyance section10of the printer main unit20to the sorting unit11. Specifically, the exit of the discharge-conveyance section10and the entrance of the sorting unit11are of substantially the same size and shape with a thickness, i.e., a height, and a width both larger than those of a continuous form of the largest size to be used. Furthermore, the positions of the exit of the discharge-conveyance section10and the entrance of the sorting unit11are the same both in level and in width direction orthogonal to the conveyance direction. If the exit of the discharge-conveyance section10and the entrance of the sorting unit11are not of the same size and shape, the exit of the discharge-conveyance section10and the entrance of the sorting unit11coincide with each other in terms of at least the levels of the lowermost parts thereof and the widthwise centers thereof.

The printer according to the embodiment of the present invention allows the insertion of an additional form feeding unit51between the printer main unit20and the sorting unit11.FIG. 4shows the additional form feeding unit51.FIG. 5shows a state where one additional form feeding unit51is added to the configuration shown inFIG. 1.

The additional form feeding unit51has in a casing thereof a form housing portion in which continuous-form rolls R3and R4are housed. In the form feeding unit51, a feed path511(a first conveyance path) and a discharge conveyance path510(a second conveyance path) extend in such a manner as to pass through the casing. The feed path511is a conveyance path extending horizontally and along which the continuous form is fed to the printer main unit20. The discharge conveyance path510is a conveyance path extending horizontally from the side near the printer main unit20toward the sorting unit11. The form feeding unit51has on one face (a feed-side face, or a second side face51A) of the casing thereof adjacent to the printer main unit20an exit514(a first exit) of the feed path511and an entrance516(a second entrance) of the discharge conveyance path510, and on another face (a discharge-side face, or a first side face51B) of the casing thereof adjacent to the sorting unit11an entrance515(a first entrance) of the feed path511and an exit517(a second exit) of the discharge conveyance path510.

A pair of rollers520provided on the feed path511functions as a first conveyor that conveys the continuous form from the entrance515to the exit514. Another pair of rollers521provided on the discharge conveyance path510functions as a second conveyor that conveys each cut sheet that has undergone recording from the entrance516to the exit517. A pair of feed rollers518functions as a sheet feeder that draws the continuous form from the roll R3and conveys the continuous form into the feed path511. Another pair of feed rollers519draws the continuous form from the roll R4and conveys the continuous form into the feed path511.

In addition to the pairs of rollers, shown inFIG. 4, provided on the feed path511and the discharge conveyance path510, guide members (not shown) that guide the continuous form (or the sheet) are also provided, actually.

The additional form feeding unit51has the same configuration as the form feeding section1. That is, units having the same configuration may be employed as the form feeding section1and the additional form feeding unit51.

In the printer shown inFIGS. 1 to 3and others, the form feeding section1is positioned between a set of devices that perform various processing operations on the continuous form or cut sheet and the sorting unit11that discharges the cut sheet that has undergone printing. In such an arrangement, attachment and removal of the continuous-form rolls R1and R2to and from the form feeding section1and removal of cut sheets from the discharge trays12,17,18, and19of the sorting unit11can be performed from one specific side of the printer. That is, the user can easily perform such operations without moving from place to place. In such an arrangement, the continuous form that has been fed from the form feeding section1and has undergone various processing operations performed in the sections of the printer main unit20is conveyed through the discharge-conveyance section10provided below the form feeding section1to the sorting unit11. That is, a feed path512extending in the form feeding section1and a discharge conveyance path513extending in the discharge-conveyance section10are arranged side by side in the vertical direction. If a unit is inserted between the printer main unit20and the sorting unit11and the feed path512or the discharge conveyance path513is blocked by the inserted unit, the conveyance path extending from the continuous-form roll to the discharge trays is blocked, disabling the performance of some processing operations. In the embodiment of the present invention, the form feeding unit51to be inserted between the printer main unit20and the sorting unit11has the feed path511and the discharge conveyance path510extending horizontally. The positions of the entrance515and the exit514of the feed path511in the form feeding unit51and the entrance of the printer main unit20(in the embodiment, the entrance of the decurling section2) coincide with one another when seen in the conveyance direction. In the embodiment, the entrance515and the exit514of the feed path511in the form feeding unit51and the entrance of the printer main unit20(the entrance of the decurling section2) are of substantially the same size and shape with a thickness, i.e., a height, and a width both larger than those of a continuous form of the largest size to be used. Furthermore, the positions of the entrance515, the exit514, and the entrance of the printer main unit20are the same both in level and in width direction orthogonal to the conveyance direction. If the entrance515, the exit514, and the entrance of the printer main unit20are not of the same size and shape, the entrance515, the exit514, and the entrance of the printer main unit20coincide with one another in terms of the levels of the lowermost parts thereof and the widthwise centers thereof.

Furthermore, the positions of the entrance516and the exit517of the discharge conveyance path510in the form feeding unit51, the exit of the printer main unit20(in the embodiment, the exit of the discharge-conveyance section10), and the entrance of the sorting unit11coincide with one another when seen in the conveyance direction. In the embodiment, the entrance516and the exit517, the exit of the printer main unit20, and the entrance of the sorting unit11are of substantially the same size and shape with a thickness, i.e., a height, and a width both larger than those of a continuous form of the largest size to be used. Furthermore, the positions of the entrance516and the exit517, the exit of the printer main unit20, and the entrance of the sorting unit11are the same both in level and in width direction orthogonal to the conveyance direction. If the entrance516and the exit517, the exit of the printer main unit20, and the entrance of the sorting unit11are not of the same size and shape, the entrance516and the exit517, the exit of the printer main unit20, and the entrance of the sorting unit11coincide with one another in terms of at least the levels of the lowermost parts thereof and the widthwise centers thereof.

The feed path511and the discharge conveyance path510extending horizontally have widths that are larger than the width of a continuous form of the largest size to be used. Therefore, by simply connecting the form feeding unit51to the printer main unit20and the sorting unit11, the feed path511and the discharge conveyance path510extending in respective directions are easily made to continue to and from the conveyance paths in the units20and11without positional deviation, whereby accurate and stable conveyance is realized. If a plurality of form feeding units51are provided, the entrances515and exits514of the feed paths511of the sheet feeding units51are positioned in such a manner as to coincide with one another when seen in the conveyance direction, in terms of at least the levels of the lowermost parts thereof and the widthwise centers thereof. Likewise, the entrances516and the exits517of the discharge conveyance paths510of the form feeding units51are positioned in such a manner as to coincide with one another when seen in the conveyance direction, in terms of at least the levels of the lowermost parts thereof and the widthwise centers thereof. Therefore, when a plurality of form feeding units51are connected to one another, the feed paths511and the discharge conveyance paths510thereof are continued from and to one another.

As described above, the printer according to the embodiment of the present invention is capable of performing printing not only on the continuous form fed from either of the two rolls R1and R2, as shown inFIGS. 1 to 3, but also on any of continuous forms of more kinds, with different sizes and/or different materials, with ease. To do so, one or more form feeding units51are merely inserted between the printer main unit20and the sorting unit11, which are provided as connectable units, and are connected thereto, and there is no need to open the printer main unit20, remove a continuous-form roll from the form feeding section1, and place another continuous-form roll into the form feeding section1. Moreover, alignment of the conveyance paths (the feed path511and the discharge conveyance path510) and other relevant operations are not necessary, realizing a very simple work. The form feeding unit51is connectable not only to the printer main unit20and the sorting unit11but also to another form feeding unit51. If it is desired to perform recording on many kinds of continuous forms, an unlimited number of form feeding units51can be added, theoretically, in accordance with the number of kinds of continuous forms. Accordingly, an unlimited number of kinds of continuous forms can be handled.

In the example shown inFIGS. 1 to 3and5, the printer main unit20initially includes one form feeding section1and one discharge-conveyance section10. The form feeding section1and the discharge-conveyance section10may be omitted from the printer main unit20(no corresponding drawings are provided) if at least one form feeding unit51is provided without fail between the printer main unit20and the sorting unit11. In such a case, naturally, a number of form feeding units51are connectable.

The arrangement of the discharge trays of the sorting unit11according to the embodiment of the present invention will now be described. Referring toFIG. 6, the conveyance path in the sorting unit11extends from near the bottom of the sorting unit11, runs along a side face of the sorting unit11remote from the printer main unit20or the form feeding unit51, and reaches a face (the top face) continued from the foregoing side face. The discharge trays of the sorting unit11are positioned both on a lateral side and on the upper side with respect to the form feeding section1(or the form feeding unit51). The large-sized-sheet discharge trays18,7121,7122, and7123and the unnecessary-sheet discharge tray19are provided on the lateral side with respect to the form feeding section1(or the form feeding unit51), i.e., on the side face of the sorting unit11. More specifically, the large-sized-sheet bulk discharge tray18having the largest capacity among the large-sized-sheet discharge trays is provided at the uppermost position on the side face of the sorting unit11, and the unnecessary-sheet discharge tray19is provided at the lowermost position on the side face of the sorting unit11. The discharge trays7121,7122, and7123provided between the large-sized-sheet bulk discharge tray18and the unnecessary-sheet discharge tray19are referred to as the large-sized-sheet discharge trays12not having large capacities. Large-sized sheets712are to be discharged to any of the large-sized-sheet discharge trays12and the large-sized-sheet bulk discharge tray18. Unnecessary sheets are to be discharged to the unnecessary-sheet discharge tray19.

The small-sized-sheet discharge trays17and717are provided on the upper side with respect to the form feeding section1(or the form feeding unit51), i.e., on the top face of the sorting unit11. Small-sized sheets711are discharged to either of the small-sized-sheet discharge trays17and717. Large-sized sheets712and small-sized sheets711mentioned herein are distinguished from each other by at least the dimension in the width direction orthogonal to the conveyance direction. Small-sized sheets711can be discharged to the large-sized-sheet discharge trays12and18, whereas large-sized sheets712cannot be discharged to the small-sized-sheet discharge trays17and717.

The technical significance of such an arrangement is as follows. The conveyance path in the sorting unit11according to the embodiment extends from near the bottom (lower side) to the top (upper side), as shown inFIG. 6. As the conveyance path becomes longer, the possibility of occurrence of a paper jam becomes higher. In addition, the possibility of occurrence of a paper jam is higher in the case of large-sized sheets712than in the case of small-sized sheets711because large-sized sheets712come into contact with more members provided in the sorting unit11. Therefore, large-sized sheets712are discharged on the upstream side in the conveyance direction with respect to the position where small-sized sheets711are discharged, whereby the length of the conveyance path for large-sized sheets712is reduced. Thus, the occurrence of a paper jam is prevented effectively. In the embodiment, the large-sized-sheet discharge trays18,7121,7122, and7123are provided on the side face of the sorting unit11(on the upstream side in the conveyance direction), and the small-sized-sheet discharge trays17and717are provided on the top face of the sorting unit11(on the downstream side in the conveyance direction). Thus, the possibility of occurrence of a paper jam is reduced. Unnecessary sheets may include those that are partially folded and/or those that are sticky because of wet ink that has not been dried sufficiently. Such sheets frequently cause paper jams. Therefore, the unnecessary-sheet discharge tray19is provided at the lowermost position on the side face of the sorting unit11, whereby the possibility of occurrence of a paper jam is further reduced. Since the unnecessary-sheet discharge tray19is provided at the lowermost position on the side face of the sorting unit11, unnecessary sheets can be relatively easily removed for disposal. In addition, if the unnecessary-sheet discharge tray19becomes full and some unnecessary sheets fall off the unnecessary-sheet discharge tray19, such sheets do not disturb the other discharge trays.

The small-sized-sheet discharge trays17and717provided on the top face of the sorting unit11have small widths. Therefore, members forming a portion of the conveyance path near the top face of the sorting unit11and other members associated therewith can be provided with small widths and light weights, as described below. That is, relatively small and light members are provided on the upper side of the sorting unit11. Therefore, the configuration of the sorting unit11can be simplified compared to a case where large and heavy members are provided on the upper side.

The internal configuration of the sorting unit11will now be described more specifically. Referring toFIG. 7, the conveyance path extending in the sorting unit11includes a main conveyance path821for large-sized sheets and a main conveyance path822for small-sized sheets. Furthermore, the main conveyance path821for large-sized sheets branches into sub-conveyance paths823to827, and the main conveyance path822for small-sized sheets branches into a sub-conveyance path828. Pairs of rollers (each pair including a conveying roller and a pinch roller)801to814and830to831that convey the sheet are provided on the foregoing conveyance paths. The conveying rollers included in the pairs of rollers801to814and830to831are driven by actuators (not shown).

Flap members815to820are provided at branch points, respectively, between the main conveyance paths821and822and the sub-conveyance paths823to828. The flap members815to820are moved by actuators1015to1020described below, and are capable of switching the direction in which the sheet advances between the main conveyance paths821and822and the sub-conveyance paths823to828.

FIG. 7shows the initial state for the conveyance of large-sized sheets712where the flap members815to820are not moved by the actuators1015to1020(seeFIG. 11). The sub-conveyance paths823to826branching off from the main conveyance paths821and822are closed by the flap members815to818(the sheet is prevented from entering the sub-conveyance paths823to826), whereas the sub-conveyance path827reaching the large-sized-sheet bulk discharge tray18is open without being closed by the flap member819. In this state, the sheet is guided into the sub-conveyance path827and is discharged to the large-sized-sheet bulk discharge tray18. The sheet to be discharged to the large-sized-sheet bulk discharge tray18in this state may not necessarily be a large-sized sheet712. A small-sized sheet711may be conveyed and be discharged to the large-sized-sheet bulk discharge tray18. Even if sheets are to be discharged without being sorted, all the sheets may be discharged to the large-sized-sheet bulk discharge tray18. The large-sized-sheet bulk discharge tray18has such a width that sheets of the largest size to be used can be received. The large-sized-sheet bulk discharge tray18has a large capacity and provides ease of removal of sheets. Therefore, the large-sized-sheet bulk discharge tray18is most frequently used even if sorting is unnecessary. In the embodiment, the state where sheets are to be discharged to the large-sized-sheet bulk discharge tray18is referred to as the non-drive initial state, where the actuators1015to1020do not need to be driven.

FIG. 8shows a state where a large-sized sheet712is being discharged to the large-sized-sheet discharge tray7121, specifically, a state where the flap member818is moved from the initial position shown inFIG. 7toward the main conveyance path821, whereby the large-sized sheet712is guided into the sub-conveyance path826toward the large-sized-sheet discharge tray7121. This concerns a case where sheets are sorted and are discharged not only to the large-sized-sheet bulk discharge tray18but also to another discharge tray.

FIG. 9shows a state where a small-sized sheet711is being discharged to the small-sized-sheet discharge tray717, specifically, a state where the flap member819is moved from the initial position shown inFIG. 7to such a position as to close the sub-conveyance path827reaching the large-sized-sheet bulk discharge tray18, and the flap member820is moved toward the main conveyance path822. Thus, the small-sized sheet711is guided from the main conveyance path821through the main conveyance path822into the sub-conveyance path828and is discharged to the small-sized-sheet discharge tray717.

FIG. 10shows a state where an unnecessary sheet101is being discharged to the unnecessary-sheet discharge tray19. For example, when any failure is detected by the inspecting section5, the flap member815is moved from the initial position shown inFIG. 7to such a position as to close the main conveyance path821and to open the sub-conveyance path823. Thus, the sheet detected to have failure is distinguished as an unnecessary sheet101from the other sheets that have been processed in a good manner, and is discharged to the unnecessary-sheet discharge tray19.

FIG. 11is a perspective view showing the internal configuration of the sorting unit11that discharges sheets as described above. For easier recognition, parts relevant to the main conveyance paths821and822are only shown. The sorting unit11includes the actuators1015to1020(in the embodiment, rotary solenoids) that move the flap members815to820. The flap members815to820in the non-drive initial state are urged by springs101to106, respectively, thereby being retained at the initial positions shown inFIG. 7. When the actuators1015to1020are driven, the flap members815to820overcome the urging forces of the springs101to106and turn about center shafts1005to1010, respectively. When the driving of the actuators1015to1020is stopped, the flap members815to820return to the initial positions with the urging forces of the springs101to106.

The springs101to104are provided on the upstream side in the conveyance direction with respect to the center shafts1005to1008provided for the flap members815to818, whereas the springs105are provided on the downstream side in the conveyance direction with respect to the center shaft1009provided for the flap member819. In the initial state, the flap member819is urged in such a direction as to open the sub-conveyance path827, unlike are the flap members815to818.

According to such a configuration, no large-sized sheets712but small-sized sheets711are conveyed toward the downstream side with respect to the flap member819. Therefore, the main conveyance path822and the sub-conveyance path828provided on the downstream side and extending near the top face of the sorting unit11can be provided with widths that correspond to the sizes of small-sized sheets711. Consequently, the sizes and weights of members to be provided near the top face of the sorting unit11can be reduced, increasing the degree of flexibility in selecting the materials and configurations of the casing of the sorting unit11and mechanisms supporting the relevant members. In the initial state, the flap member819is urged in such a direction as to open the sub-conveyance path827, opposite to the direction in which the other flap members815to818provided on the upstream side in the conveyance direction with respect thereto are urged. Therefore, even if the actuators1015to1020should fail and the flap members815to820should be immovable, there is no chance that a large-sized sheet712enters the main conveyance path822on the downstream side with respect to the flap member819. Accordingly, the occurrence of a paper jam due to the entrance of a large-sized sheet712into the conveyance paths822and828for small-sized sheets is prevented, and the main conveyance path822and the sub-conveyance path828can be downsized, as described above.

To summarize, according to the present invention, the number of kinds of sheets, as recording media, to be handled can be easily increased arbitrarily, which has not been considered in, for example, Japanese Patents Laid-Open No. 5-4773 and No. 9-301623. Accordingly, high expandability is realized. Moreover, since both feeding and discharging of sheets are performed on one specific side of the printer, good operability is provided and a downsized configuration is realized.

Furthermore, the large-sized-sheet discharge trays are provided on the upstream side in the conveyance direction with respect to the small-sized-sheet discharge trays, whereby no large-sized sheets are allowed to be conveyed to the downstream portion of the conveyance path. Therefore, the sizes and weights of the conveyance paths, discharge trays, and relevant members provided in the downstream portion can be reduced in accordance with the sizes of small-sized sheets to be handled. Accordingly, the configuration of the sorting unit can be simplified and, with an increased degree of flexibility in the selection of materials and configurations, costs can be reduced. Furthermore, since no large-sized sheets are conveyed to the downstream portion of the conveyance path, the possibility of occurrence of a paper jam is reduced. Furthermore, by positioning one of the large-sized-sheet discharge trays that has the largest capacity (the large-sized-sheet bulk discharge tray) at the uppermost position on the side face of the sorting unit, relatively high operability is realized even though the discharge trays are not provided at large intervals. In addition, by positioning the unnecessary-sheet discharge tray on the upstream side in the conveyance direction with respect to the large-sized-sheet discharge trays, unnecessary sheets having some failure are prevented from being conveyed to the downstream portion of the conveyance path, whereby the occurrence of a paper jam due to an unnecessary sheet is prevented.

This application claims the benefit of Japanese Patent Application No. 2010-103797 filed Apr. 28, 2010, which is hereby incorporated by reference herein in its entirety.