Recording apparatus

Disclosed is a recording apparatus that helps to achieve a reduction in size and cost. The recording apparatus has a U-turn sheet feeding mechanism for reversing and feeding a recording medium and a duplex transport mechanism for reversing the recording medium and performing printing on both sides thereof, in which the same transport path serves as a transport path for transporting the recording medium from a U-turn sheet feeding roller to a main transport roller for transporting the recording medium to a printing portion and as a transport path for reversal in duplex transport. Further, a transport roller provided in the transport path from the U-turn sheet feeding roller to the main transport roller for transporting the recording medium to the printing portion is the same as a transport roller for duplex transport. A single transport roller serves both as the U-turn transport roller and as the duplex transport roller.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording apparatus that performs recording on a recording sheet by a recording means.

2. Related Background Art

A conventional recording apparatus will be described with reference toFIG. 24.

InFIG. 24, reference numeral901indicates a recording head that performs recording by selectively discharging ink from a plurality of discharge ports. The recording head901is retained in position by a carriage (not shown), and reciprocates in a direction perpendicular to the conveying direction of a recording medium, thereby performing printing on the recording medium. Reference numeral902indicates a platen opposed to the recording head, and retains the recording medium at a printing portion.

Next, a U-turn feeding structure will be described.

Reference numeral905indicates a sheet feeding cassette that retains recording mediums in a stacked state, reference numeral906indicates a U-turn sheet feeding roller for separately conveying the recording mediums, reference numeral910indicates a paper guide on the inner side of a U-turn portion, reference numeral911indicates a paper guide on the outer side of the U-turn portion, reference numeral907indicates a U-turn transport roller, reference numeral908indicates a U-turn transport roller adapted to be driven to rotate while pressurizing the U-turn transport roller907, reference numeral903indicates a transport roller pair for transporting the recording medium to a printing portion, reference numeral913indicates a paper guide for guiding the recording medium to the transport roller pair903, reference numeral904indicates an ejection roller pair for ejecting the recording medium, and reference numeral909indicates an ejection tray retaining the ejected recording medium. Reference numeral912indicates a U-turn paper guide flapper for switching between U-turn transport and reversal transport for two-side recording.

Next, a U-turn sheet feeding operation will be described.

The recording mediums stacked in the sheet feeding cassette905are separately transported in the direction of the arrow M by the U-turn sheet feeding roller906, further transported in the direction of the arrow N by the U-turn transport roller907and the U-turn transport roller908, and transported in the direction of the arrow P while guided by the paper guides910,911, and913. At this time, the U-turn paper guide flapper912moves in the direction of the arrow Q (indicated by the dashed line) to secure the U-turn transport path. Next, the recording medium is transported to the printing portion by the transport roller pair903, and printing is effected by the recording head901. Then, the recording medium is transported in the direction of the arrow U by the ejection roller pair904, and ejected onto the ejection tray909.

Next, a two-side printing structure will be described.

Reference numerals914and915indicate duplex transport rollers, reference numeral916indicates duplex transport rollers adapted to be driven to rotate while pressurizing the duplex transport rollers914and915, reference numeral917indicates outer paper guides for duplex transport, reference numerals918and919indicate inner paper guides for duplex transport, and reference numeral920indicates a two-side paper guide flapper for switching the transport path before and after reversal in duplex transport.

Next, a two-side printing operation will be described.

Printing is performed by the recording head901on the recording medium fed by the U-turn sheet feeding mechanism; when the printing on the obverse side is completed, the transport roller pair903and the ejection roller pair904are reversed in rotation to transport the recording medium in the direction of the arrow R. The recording medium is further transported in the direction of the arrow S by the transport roller pair903, and transported to a duplex transport portion. At this time, the U-turn paper guide flapper912moves in the direction of the arrow T, and the two-side paper guide flapper920moves in the direction of the arrow K, securing the transport path for the recording medium in the direction of the arrow S.

Further, the recording medium is transported by the duplex transport rollers914and915and the duplex transport rollers916, and guided by the paper guides917,918, and919to be transported in the directions of the arrows H and I. The recording medium is transported again in the direction of the arrow P toward the transport roller pairs903in a reversed state. At this time, the two-side paper guide flapper920moves in the direction of the arrow L (indicated by the dashed line), securing the transport path after reversal. Printing is performed on the reverse side of the reversed recording medium by the recording head1, and, when the printing is completed, the recording medium is ejected onto the ejection tray909, thereby completing the two-side printing.

The above-described conventional example has the following problems.

Since the paper transport path is independent, mounting of the U-turn sheet feeding mechanism and the two-side printing mechanism results in an increase in the size of the apparatus main body in height direction and depth direction, thus hindering achievement of a reduction in size. Further, the provision of the independent transport mechanism leads to an increase in cost, which means the construction cannot be adopted in an inexpensive apparatus.

Further, to cope with jamming due to defective transport of a recording medium, it is necessary to provide a mechanism allowing opening of the paper guide portion; in this case also, the transport mechanism is independent, and the paper guide portion opening mechanism is also formed separately, which leads to an increase in apparatus size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a recording apparatus that helps to achieve a reduction in size and cost.

It is another object of the present invention to provide a recording apparatus comprising:

a U-turn sheet feeding roller for reversing and feeding a recording medium; a main transport roller for transporting the recording medium on an upstream side of a recording head; a reversing mechanism for turning the recording medium upside down; a first transport path for transporting the recording medium from the U-turn sheet feeding roller to the main transport roller; a second transport path for transporting the recording medium in the reversing mechanism, the second transport path sharing a portion thereof with the first transport path; and a third transport path arranged in the portion shared by the first and second transport paths and adapted to transport a recording medium of high rigidity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1 of the present invention will be described with reference toFIGS. 1 through 4.FIG. 1is a main body sectional view showing Embodiment 1,FIGS. 2 and 3are main body sectional views showing a drive construction, andFIG. 4is a perspective view showing how a thick recording medium, such as a CD or DVD, is transported.

InFIG. 1, reference numeral1indicates a recording head that discharges ink selectively from a plurality of discharge ports to perform recording. The recording head1is retained in position by a carriage (not shown), and reciprocates in a direction perpendicular to the recording medium transporting direction to perform printing on a recording medium. Reference numeral2indicates a platen opposed to the recording head1and retains the recording medium at a printing portion.

Next, a U-turn sheet feeding structure will be described.

Reference numeral5indicates a sheet feeding cassette retaining recording mediums in a stacked state, reference numeral6indicates a U-turn sheet feeding roller for separately transporting the recording mediums, reference numeral23indicates a paper guide for guiding the outer side of the recording medium at the time of U-turn sheet feeding and at the time of duplex transport, reference numeral21indicates a U-turn transport roller for transporting the recording medium at the time of U-turn sheet feeding and at the time of duplex transport, reference numeral25indicates a U-turn transport roller adapted to be driven to rotate while pressurizing the U-turn transport roller21, reference numeral3indicates a main transport roller pair for transporting the recording medium to the printing portion, reference numeral26indicates a paper guide for guiding the recording medium to the main transport roller pair3, reference numeral4indicates an ejection roller pair for ejecting the recording medium, and reference numeral9indicates an ejection tray for retaining the ejected recording medium. Reference numeral24indicates a paper guide flapper weakly urged in the direction of the arrow K, using a portion24B as the rotation center, to abut the paper guide26. The paper guide flapper24guides the inner side of the recording medium at the time of U-turn sheet feeding and at the time of duplex transport.

Next, a U-turn sheet feeding operation will be described.

The recording mediums stacked in the sheet feeding cassette5are separately transported in the direction of the arrow M by the U-turn sheet transport roller6, further transported in the direction of the arrow by the U-turn transport roller21and U-turn transport rollers25, and transported in the direction of the arrow I while guided by the paper guide26and the paper guide flapper24. At this time, the recording medium is urged with low pressure toward the paper guide flapper24and the paper guide26, so that it can pass between the paper guide26and the paper guide flapper24. The recording medium is further transported in the direction of the arrow P to the printing portion by the main transport roller pair3, and printing is performed thereon by the recording head1; the recording medium is then transported in the direction of the arrow U by the ejection roller pair4, and ejected onto the ejection tray9.

Next, a two-side printing structure will be described.

Reference numerals22and27indicate paper guides for guiding the outer side of the recording medium at the time of duplex transport. The paper guide flapper24has a guide portion24A for guiding the inner side of the recording medium at the time of duplex transport.

Next, a two-side printing operation will be described.

The recording medium fed by the U-turn sheet feeding mechanism undergoes printing by the recording head1; when the printing on the obverse side is completed, the main transport roller pair3and the ejection roller pair4are reversed in rotation to transport the recording medium in the direction of the arrow R. The recording medium is further transported in the direction of the arrow S by the main transport roller pair3, and transported to a duplex transport portion. At this time, the recording medium is transported while guided by the paper guide portion24A of the paper guide flapper24and the paper guide27.

Further, while guided by the paper guide27, the recording medium is transported in the direction of the arrow H, effecting joining with the U-turn sheet feeding transport path. The transport from this onward is the same as that at the time of U-turn sheet feeding, the recording medium being transported in the directions of the arrows N and I. In a reversed state, the recording medium is transported again in the direction of the arrow P toward the main transport roller pair3. Printing is performed on the reverse side of the reversed recording medium by the recording head1; after the completion of the printing, the recording medium is ejected onto the ejection tray9, thus completing the two-side printing.

Next, the construction of a horizontal path for performing printing on a thick printing medium, such as a CD or a DVD, will be described with reference toFIGS. 1 through 4.

The paper guide23for guiding the outer side of the recording medium at the time of U-turn sheet feeding and at the time of duplex transport is equipped with a guide hole23B for guiding the recording medium in the horizontal path.

The paper guide portion24A of the paper guide flapper24is arranged outside the region where a thick recording medium is transported in the horizontal path. In the horizontal path, the thick recording medium is transported while guided by the paper guide24. Further, as shown inFIG. 4, when transported, a thick recording medium55, such as a CD or a DVD, is set in position on a transport tray54. The U-turn transport roller21is composed of a roller shaft21A and rubber portions separately arranged thereon, with the rubber portions being arranged outside the region where the thick recording medium is transported in the horizontal path. Due to this construction, the transport tray54can overlap the U-turn transport roller21during transport.

Next, the transport operation in the horizontal path will be described.

InFIG. 1, the transport tray54with the recording medium55consisting of a CD, DVD or the like placed thereon is inserted from the ejection side in the direction of the arrow J, and transported in the direction of the arrow R by reverse operation of the ejection roller pair4and the main transport roller pair3. Further, the transport tray is transported in the direction of the arrow V while guided by the paper guides26,27and the paper guide flapper24to reach the guide hole23B of the paper guide23. Next, the main transport roller pair3and the ejection roller pair4are caused to make normal rotation to transport the transport tray54in the direction of the arrow P. At this time, recording head1performs printing on the recording medium55, such as a CD or a DVD, placed on the transport tray54; after the completion of the printing, the transport tray is ejected in the direction of the arrow U, thus completing the printing in the horizontal path.

Next, a construction for an anti-jam processing to be performed when jamming has occurred due to a transport error during U-turn sheet feeding, duplex transport, or horizontal path transport will be described.

InFIG. 1, the paper guide23for guiding the outer side of the recording medium at the time of U-turn sheet feeding and at the time of duplex transport can be opened and closed using a rotation shaft23A as the rotation center. When performing anti-jam processing, the paper guide23is opened in the direction of the arrow W, whereby it is possible to remove the jammed recording medium.

Next, the drive construction of the U-turn sheet feeding roller6and the U-turn transport roller21will be described with reference toFIGS. 2 and 3.

Reference numeral41indicates a U-turn transport roller gear provided on the shaft of the U-turn transport roller21, reference numeral42indicates a U-turn sheet feeding roller gear provided on the shaft of the U-turn sheet feeding roller6and having a one-way clutch mechanism (not shown) transmitting driving force solely in the sheet feeding direction, reference numeral39indicates a drive motor, reference numeral40indicates a motor gear arranged on a motor shaft39A of the drive motor39, reference numerals50,52, and53indicate pendulum idler gears on which positioning is effected with a pendulum gear holder51using the motor gear40as the rotation center, and reference numerals43,44, and49indicated U-turn sheet feeding idler gears for transmitting driving force from the motor gear40to the U-turn sheet feeding roller gear42.

Next, a separating operation in U-turn sheet feeding will be described with reference toFIG. 2.

When the motor gear40rotates in the normal direction, i.e., in the direction of the arrow A, the pendulum gear holder51swings in the direction of the arrow Y. Then, the pendulum idler gear50is brought into mesh with the U-turn transport roller gear41, and the U-turn transport roller21rotates in the direction of the arrow C.

At this time, the pendulum idler gear52is separated from the U-turn transport roller gear41by the swinging in the direction of the arrow Y of the pendulum gear holder51, and no driving force is transmitted. At the same time, driving force is transmitted to the U-turn sheet feeding roller gear42through the U-turn sheet feeding idler gears43,44, and49, and the U-turn sheet feeding roller6rotates in the direction of the arrow X, the recording medium being separated to be fed. When the recording medium is fed and reaches the nip portion between the U-turn transport roller21and the U-turn transport roller25, the sheet feeding operation is completed (FIG. 1).

Next, a transport operation in U-turn sheet feeding will be described with reference toFIG. 3.

When the sheet feeding operation is completed, the motor gear40is reversed to rotate in the direction of the arrow F; then, the pendulum gear holder51swings in the direction of the arrow Z, and the pendulum idler gear52is meshed with the U-turn transport roller gear41, the U-turn transport roller21rotating in the direction of the arrow C as in the case of sheet feeding.

At this time, the pendulum idler gear50is separated from the U-turn transport roller gear41by the swinging in the Z-direction of the pendulum gear holder51, and no driving force is transmitted. On the other hand, driving force is transmitted to the U-turn sheet feeding roller gear42through the U-turn sheet feeding idler gears43,44, and49; however, due to the above-described one-way clutch mechanism, the driving of the U-turn sheet feeding roller gear42is not transmitted to the U-turn sheet feeding roller6, and the U-turn sheet feeding roller6is brought to a stop.

Next, a two-side printing operation will be described with reference toFIG. 3.

When the motor gear40is reversed to rotate in the direction of the arrow F, the U-turn transport roller21rotates in the direction of the arrow C. By the rotation of the U-turn transport roller21in the direction of the arrow C, transport for two-side printing is conducted. At this time, the U-turn sheet feeding roller6is at rest due to the above-described drive construction, and no sheet feeding operation is conducted. Otherwise, the operation is the same as the above-described transport operation for two-side printing, so that a description thereof will be omitted.

As described above, commonality is achieved between the transport path for U-turn sheet feeding and the transport path for two-side printing, as well as overlapping with the horizontal path, whereby it is possible to realize a reduction in size and cost.

In Embodiment 1 described above, the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are the same. In Embodiment 2, the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are opposite to each other.

A U-turn sheet feeding operation will be described with reference toFIG. 5.

This embodiment differs from Embodiment 1 in that a paper guide flapper30is added to the forward end of the paper guide22. The paper guide flapper30has a rotation center30A, around which it is weakly urged toward the paper guide23. Since the paper guide flapper30is urged with a low pressure, the recording medium can pass between the paper guide23and the paper guide flapper30. The recording medium fed by the U-turn sheet feeding roller6is transported in the direction of the arrow M, and is transported in the direction of the arrow while guided by the paper guide23and the paper guide flapper30. The operation from this onward is the same as that in Embodiment 1, so that a description thereof will be omitted. The construction of the horizontal path for performing printing on a thick recording medium, such as a CD or a DVD, is the same that of Embodiment 1, so that a description thereof will be omitted.

Next, a two-side printing structure will be described with reference toFIG. 6.

The operation from the U-turn sheet feeding to the surface printing operation is the same as that in Embodiment 1, so that a description thereof will be omitted. When the surface printing is completed, the main transport roller pair3and the ejection roller pair4are reversed in rotation, and the recording medium is transported in the direction of the arrow R. The recording medium is further transported in the direction of the arrow b by the main transport roller pair3, and is transported to the duplex transport portion. At this time, the paper guide flapper24moves in the direction of the arrow a, thus securing the transport path.

Further, conversely to U-turn sheet feeding, the U-turn sheet transport roller21rotates in the direction of the arrow e. As a result, the recording medium is transported in the directions of the arrows d and f while guided by the paper guide26, the paper guide flapper24, the paper guide23, and the paper guide flapper30. Further, the recording medium is transported in the direction of the arrow P while guided by the abutment portion of the paper guide27and the paper guide flapper24, whereby the recording medium reversing operation is completed. At this time, the paper guide flapper24abuts the paper guide27with a low pressure, so that the recording medium is allowed to pass. The transport operation from this onward is the same as that in Embodiment 1, so that a description thereof will be omitted.

In Embodiment 1, the U-turn sheet feeding mechanism is arranged at a position separate from the transport path for two-side printing. In Embodiment 3, the U-turn sheet feeding mechanism is formed in the transport path for two-side printing, thereby achieving a further reduction in size.

A U-turn sheet feeding operation will be described with reference toFIG. 7.

This embodiment differs from Embodiment 1 in that the U-turn sheet feeding roller6is eliminated and that there is added a separation roller38adapted to abut the U-turn transport roller21to separate the recording medium. In this construction, the U-turn transport roller21also serves as the sheet feeding roller. Further, there is provided a middle plate37for bringing the recording medium P into press contact with the U-turn transport roller21. Through rotation of the U-turn transport roller21, the recording medium P is transported in the direction of the arrow M. Then, the recording medium is separated at the nip portion between the U-turn transport roller21and the separation roller38and is transported in the direction of the arrow N. When the separation of the recording medium is completed, the middle plate37retracts in the direction of the arrow g, and moves to a position where the next sheet feeding is not conducted. The transport operation from this onward is the same as that in Embodiment 1, so that a description thereof will be omitted.

The construction of the horizontal path for performing printing on a thick recording medium, such as a CD or a DVD, is the same that of Embodiment 1, so that a description thereof will be omitted.

Next, a two-side printing structure will be described with reference toFIG. 8.

The operation from the U-turn sheet feeding to the surface printing operation is the same as that in Embodiment 1, so that a description thereof will be omitted. When the surface printing is completed, the main transport roller pair3and the ejection roller pair4are reversed in rotation, and the recording medium is transported in the direction of the arrow R. The recording medium is further transported in the direction of the arrow S by the main transport roller pair3, and is transported to the duplex transport portion. At this time, the recording medium is transported while guided by the paper guide24A of the paper guide flapper24and the paper guide27. Further, the recording medium is transported in the direction of the arrow H while guided by the paper guides27and22, and meets the U-turn sheet feeding transport path. At this time, the middle plate37retracts in the direction of the arrow g, and the separation roller38also retracts in the direction of the arrow h, thus securing the transport path. The transport operation from this onward is the same as that in the U-turn sheet feeding operation, so that a description thereof will be omitted.

In Embodiment 1, there is provided a single U-turn transport roller for transporting the recording medium at the time of U-turn sheet feeding and at the time of duplex transport. In Embodiment 4, two U-turn transport rollers are provided. By providing two U-turn transport rollers, it is possible to avoid overlapping of the horizontal path and the transport roller, and, in addition to the thick recording medium, such as a CD or a DVD, a thick paper sheet of A4 width can also be transported in the horizontal path.

A U-turn sheet feeding operation will be described with reference toFIG. 9.

This embodiment differs from Embodiment 1 in that there are added a second U-turn transport roller22and paper guides28and29. Further, the position of the paper guide flapper24is changed. The recording medium fed by the U-turn sheet feeding roller6is transported in the direction of the arrow M, and transported in the direction of the arrow j while guided by the paper guides22,23,28, and29, and is further transported in the directions of the arrows N, I, and P by the second U-turn transport roller22. At this time, the paper guide flapper24moves in the direction of the arrow i to secure the transport path. The transport operation from this onward is the same as that in Embodiment 1, so that a description thereof will be omitted.

Next, the construction of the horizontal path for performing printing on a thick recording medium, such as a CD or a DVD, will be described.

The paper guide23for guiding the outer side of the recording medium during U-turn sheet feeding and duplex transport is equipped with the guide hole23B for guiding the recording medium in the horizontal path.

The paper guide flapper24moves in the direction of the arrow i to secure the transport path of the horizontal path. In the horizontal path, the recording medium is guided by the paper guides26and27, the paper guide flapper24, the paper guides28and29, and the guide hole23B of the paper guide23. While in Embodiment 1 the recording medium transport path in the horizontal path and the U-turn transport roller21overlap each other, by arranging two transport rollers (21and22), there is no overlapping of the recording medium transport path in the horizontal path and the U-turn transport rollers21and22, so that, in addition to a CD, a DVD, or the like, a thick paper sheet of A4 width can also be transported. Otherwise, the construction of the horizontal path is the same as that of Embodiment 1, so that a description thereof will be omitted.

Next, a two-side printing operation will be described with reference toFIG. 10.

The operation from the U-turn sheet feeding to the surface printing is the same as that in Embodiment 1, so that a description thereof will be omitted. When the surface printing is completed, the main transport roller pair3and the ejection roller pair4are reversed in rotation to transport the recording medium in the direction of the arrow R. The recording medium is further transported in the direction of the arrow S by the main transport roller pair3, and is transported to the duplex transport portion. At this time, the paper guide flapper24moves in the direction of the arrow K to secure the transport path. Further, the recording medium is transported in the directions of the arrows H, j, and N while guided by the paper guide27, the paper guide flapper24, and the paper guides22,23,28, and29. The transport operation from this onward is the same as that of Embodiment 1, so that a description thereof will be omitted.

In Embodiment 2 described above, a single U-turn transport roller is provided, and the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are opposite to each other. In Embodiment 5, two U-turn transport rollers are provided, and the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are opposite to each other.

A U-turn sheet feeding operation and a recording medium transport operation in the horizontal path will be described with reference toFIG. 11.

This embodiment is the same as Embodiment 4 in that two U-turn transport rollers (21and22) are provided, and the same as Embodiment 2 in that the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are opposite to each other, so that a description of these features will be omitted.

Next, a two-side printing operation will be described with reference toFIG. 12.

This embodiment is the same as Embodiment 4 in that two U-turn transport rollers (21and22) are provided, and the same as Embodiment 2 in that the recording medium transport direction in U-turn sheet feeding and the recording medium transport direction in two-side printing are opposite to each other, so that a description of these features will be omitted.

In Embodiment 2 described above, a pendulum gear is used for driving force transmission from the drive motor39to the U-turn transport roller21. In Embodiment 6, a one-way clutch is used instead of the pendulum gear. Embodiment 6 will be described with reference toFIGS. 13 and 14.

This embodiment differs from Embodiment 1 in that there are two driving paths from the motor gear40to the U-turn transport roller gear41. One path connects the motor gear40to the U-turn transport roller gear41by way of idler gears45and47. The other path connects the motor gear40to the U-turn transport roller gear41by way of an idler gear46. The idler gear47is formed by a double gear and has a speed reduction mechanism. This makes it possible to reduce the transport speed as compared with that in the other driving path. Further, it is also possible for the double gear of the idler gear47to have a speed increasing mechanism, making it possible to increase the transport speed as compared with that in the other driving path.

Further, the idler gear45or47is provided with a one-way clutch mechanism (not shown) for transmitting driving force solely in the direction of the arrow inFIG. 13. Similarly, the idler gear46is also provided with a one-way clutch mechanism (not shown) for transmitting driving force solely in the direction of the arrow inFIG. 14. From the motor gear40to the U-turn sheet feeding roller gear42, driving connection is effected by idler gears43and44.

Next, a U-turn sheet feeding operation will be described with reference toFIG. 13.

When the motor gear40is driven in the normal direction to rotate in the direction of the arrow1, the idler gears45and47rotate in the directions of the arrows, and driving force is transmitted to the U-turn transport roller gear41, causing the U-turn transport roller21to rotate in the direction of the arrow C. In this process, due to the one-way clutch mechanism formed in the idler gear46, no driving force is transmitted to one driving path to the U-turn transport roller gear41. On the other hand, driving force is transmitted from the U-turn sheet feeding roller gear42through the idler gears43and44, and the recording medium is separated and fed. When the recording medium is fed, and reaches the nip portion between the U-turn transport roller21and the U-turn transport roller25, the sheet feeding operation is completed (FIG. 1).

Next, a transport operation in U-turn sheet feeding will be described with reference toFIG. 14.

When the sheet feeding operation is completed, the motor gear40is reversed to rotate in the direction of the arrow m; then, the idler gear46rotates in the direction of the arrow, transmitting driving force to the U-turn transport roller gear41. As in the sheet feeding operation, this causes the U-turn transport roller21to rotate in the direction of the arrow C. At this time, due to the one-way clutch mechanism provided in the idler gear45or47, no driving force is transmitted from the other driving path to the U-turn transport roller gear41.

Further, while driving force is transmitted to the U-turn sheet feeding roller gear42through the U-turn sheet feeding idler gears43and44, due to the one-way clutch mechanism, no driving force is transmitted from the U-turn sheet feeding roller gear42to the U-turn sheet feeding roller gear6, which is brought to a stop.

Next, an operation in two-side printing will be described with reference toFIG. 14.

When the motor gear40is reversed to rotate in the direction of the arrow m, the U-turn transport roller21rotates in the direction of the arrow C. By the rotation of the U-turn transport roller21in the direction of the arrow C, the transport in two-side printing is effected. At this time, due to the above-described drive construction, the U-turn sheet feeding roller6is at rest, and no sheet feeding operation is conducted. Otherwise, this embodiment is the same as Embodiment 1, so that a further description thereof will be omitted.

In Embodiments 1 and 6 described above, the drive motor39is used to drive the U-turn transport roller21. In Embodiment 7, driving force is transmitted to the U-turn transport roller21from the drive motor for driving the main transport roller pair3or the ejection roller pair4. In this embodiment also, due to the pendulum gear or the one-way clutch mechanism, even if the main transport roller pair3or the ejection rollers4make normal and reverse rotation, the U-turn transport roller21rotates in one direction only.

In Embodiment 1 described above, a construction in which a commonality is achieved between the U-turn sheet feeding transport path and the duplex transport path is incorporated into the apparatus main body. In Embodiment 8, the transport portion for U-turn sheet feeding and duplex transport is formed as a unit, which is detachably mountable to the apparatus main body. Embodiment 8 will be described with reference toFIG. 15.

An apparatus main body48is equipped with a mechanism for feeding sheets from above. Reference numeral31indicates a sheet feeding roller for separately feeding recording mediums, and reference numeral32indicates a stacking portion where recording mediums are stacked together. A recording medium fed by the sheet feeding roller31is transported to the main transport roller pair3while guided by a paper guide flapper34and a paper guide35. The operations from printing on the recording medium to sheet ejection are the same as those in Embodiment 1, so that a description thereof will be omitted. A U-turn-sheet-feeding/duplex-transport unit56allows separation between a section formed by main body frames36and33of the apparatus main body48and a section formed by the paper guide portions23and27of the U-turn-sheet-feeding/duplex-transport unit56. The construction of the transport portion is the same as that of Embodiment 1, so that a description thereof will be omitted.

In effecting the connection of the U-turn-sheet-feeding/duplex-transport unit56to the apparatus main body48, positioning/fixing is effected by a positioning portion (not shown), and the mounting of the unit is detected by an electric detecting portion (not shown). When the mounting of the unit is detected, printer control is effected through control in correspondence with U-turn sheet feeding and two-side printing.

A standard recording apparatus according to this embodiment has a mechanism for feeding sheets from above the apparatus main body, functions to perform U-turn sheet feeding, duplex transport, and the transport of a thick recording medium, such as a CD or a DVD, and, further, a transport path allowing two-side printing on not only a cut paper sheet, such as an A4 size or letter size sheet but also a smaller size cut sheet such as an L-print size. Further, the recording apparatus of this embodiment has a transport path which allows, even in U-turn sheet feeding and two-side printing, not only the feeding of sheets from above but also the transport of a recording medium of high quality that does not easily bend.

The transport path of the recording apparatus of Embodiment 9 will be described with reference toFIG. 16.

As in Embodiment 4, in this embodiment, there are provided two U-turn transport rollers (21and22). This makes it possible to secure the horizontal path for transporting a thick recording medium, such as a CD or a DVD, without involving an increase in the size of the main body, and to arrange the transport rollers at positions corresponding to various recording medium widths, such as A4, B5, A5, 2L-print, 4×6 size, postcard, envelope, and L-print size.

Reference numeral101indicates a duplex transport roller, which is rotatably set in position in a U-turn transport unit casing108. A U-turn sheet feeding roller6has a semicircular configuration, and is arranged in the duplex transport path in order to achieve a reduction in the size of the main body. Further, a separation roller38in contact with the U-turn sheet feeding roller6and a holder104holding the separation roller38are arranged outside the transport path for U-turn sheet feeding and the transport path for duplex transport.

Reference numeral111indicates a first detection lever, and reference numeral112indicates a first detection sensor for detecting the operation of the first detection lever111. The first detection lever111is arranged at a position where the transport paths for sheet feeding from above, U-turn sheet feeding, and duplex transport join, and detects the leading end and trailing end of a recording medium. Here, a thick recording medium, such as a CD or a DVD, is transported so as to be offset from the first detection lever111with respect to the width direction of the recording medium. This helps to prevent the thick recording medium, such as a CD or a DVD, and the first detection lever111from coming into contact with each other.

Reference numeral113indicates a second detection lever, and reference numeral114indicates a second detection sensor for detecting the operation of the second detection lever113. The second detection lever113is arranged in the common transport path for U-turn sheet feeding and duplex transport and in the vicinity of a two-side flapper110, and performs detection of the presence/absence and the trailing end of a recording medium during U-turn sheet feeding and detection of the leading end and trailing end of a recording medium during duplex transport. Further, it is also possible to perform detection as to whether or not a recording medium is sticking out of the sheet feeding cassette5to block the transport path for duplex transport. In order to prevent the second detection lever113from being abruptly caused to rotate by the ascent of the middle plate37to thereby generate noise during U-turn sheet feeding when the middle plate37is to be raised by a cam provided on the shaft of the U-turn sheet feeding roller6, the second detection lever113is retracted upwards before the middle plate37and the recording medium P come into contact with each other, restoring the second detection lever113so that it may abut the recording medium P after the middle plate37has ascended. Due to this operation, it is possible to detect the presence/absence of a recording medium while preventing generation of noise.

As guide members on the outer side of the U-turn sheet feeding transport path, there are provided a guide portion108aconstituting a part of the casing108of the U-turn transport unit, a guide23also serving as an opening/closing portion for anti-jam processing, a lower surface portion117aof an upper-side sheet feeding unit casing117, an upper-side sheet feeding guide flapper34, and a paper guide portion118supporting a pinch roller of the main transport roller pair3and rotatably supporting the first detection lever111. Further, as guide members on the inner side of the U-turn sheet feeding transport path, there are provided a guide portion105aconstituting a part of an inner guide105of the duplex transport portion, a paper guide106arranged between two U-turn transport rollers21and22, a guide portion108bconstituting a part of the U-turn transport unit casing108, an upper guide portion109aof a paper guide109downwardly swingable around the center axis of a main transport roller3-1of the main transport roller pair3, and an upper guide portion24cof a paper guide24rotatably mounted to the paper guide109at a center axis portion24b. Here, a space SA above the guide portion108bis a clearance portion for a loop when performing registration; it is a clearance portion for the S-shaped portion of a recording medium formed during registration by a recording medium bending force generated due to the fact that the nip portion of the main transport roller pair3is arranged so as to be offset downstream with respect to the transporting direction of the recording medium.

As the guide members on the outer side of the duplex transport path, there are provided a paper guide portion109cconstituting a part of a paper guide109downwardly swingable, a paper guide portion120aconstituting a part of a casing base120of the recording apparatus, an under paper guide103for anti-jam processing mounted so as to be rotatable around a rotation shaft103awith respect to the U-turn transport unit casing108while rotatably supporting a two-side pinch roller102adapted to rotate with the duplex transport roller101, and a two-side flapper110mounted to the U-turn transport unit casing108so as to be rotatable around a rotation shaft110aand adapted to effect switching between the transport path for U-turn sheet feeding and the duplex transport path. Due to this construction, the downstream side transport path is the same as the above-described transport path for U-turn sheet feeding. Further, as the guide members on the inner side of the duplex transport path, there are provided a lower guide portion24dof the rotatable paper guide24, a lower guide portion109bof the paper guide109, and a guide portion105bof the paper guide105rotatably supporting the second detection lever113. Further, to reduce the resistance in the transport of a recording medium, the paper guide105is provided with a roller119which is rotatable.

Next, the transport path in this embodiment will be described.

In the U-turn transport portion, the outer guide has an arcuate configuration, whereas the inner guide106arranged between the two U-turn transport rollers21and22is formed so as to clear inwards. The clearance portion SB is of a configuration as required for the transport of a highly rigid recording medium by the two U-turn transport rollers. It functions as a clearance portion to be utilized when inward wrapping of the recording medium occurs due to a difference in transporting force between the two rollers or depending on the balance in transport resistance due to the guide portion. If a stationary paper guide portion is provided without securing the clearance portion SB, the following problem will be involved: when the trailing end of the recording medium leaves the first U-turn transport roller21on the upstream side, the recording medium, which has been bent by the two U-turn transport rollers, is restored to the original shape by its own rigidity, and gets caught between the paper guide23provided on the outer side and the stationary paper guide portion provided on the inner side, resulting in an increase in transport resistance. This leads to a deterioration in image quality.

FIGS. 17A and 17Bare sectional views of the U-turn transport portion. The inner guide106arranged between the two U-turn transport rollers21and22is provided with a driven roller107. As shown inFIG. 17A, when the recording medium P is being transported while in contact with the upstream portion of the first U-turn transport roller21of the paper guide23, the recording medium P is not in contact with the driven roller107. As shown inFIG. 17B, when the trailing end of the recording medium P is detached from the upstream portion of the first U-turn transport roller21of the paper guide23, and leaves the nip portion between the first U-turn transport roller21and the U-turn transport roller25, the recording medium P comes into contact with the driven roller107. This helps to restrain changes in the behavior of the recording medium P when it leaves the nip portion. Even after the trailing end of the recording medium P has left the nip portion, the recording medium P is transported while in contact with the driven roller107. Here, in order to restrain changes in the behavior of the recording medium when it leaves the nip portion of the U-turn transport roller21, and to prevent it from constituting a resistance to the transport of the recording medium afterwards, it is desirable for the driven roller107to be arranged downstream and in the vicinity of the first U-turn transport roller21.

Next, to obtain in the duplex transport path an image equivalent to that in the U-turn sheet feeding transport path, it is necessary for the U-turn sheet feeding transport path and the duplex transport path to have the same transport resistance.FIG. 18is a schematic explanatory view of the duplex transport path and the U-turn sheet feeding path. As shown inFIG. 18, to diminish the difference in the reaction force generated by the rigidity of the recording medium, it is necessary, as an imaginary circle UTD of the U-turn transport portion is approached, to at least expand outward by from a common tangent DPP1to the main transport roller3-1and the imaginary circle UTD of the U-turn transport portion, which constitutes the shortest passage, bringing the U-turn transport path Up and the duplex transport path Dp close to each other (DPP2to DPP2OUT). In other words, the angle made by Up and Dp is made Dθ2, which is smaller than Dθ1(ideally, Dθ2=0 for the same transport path). However, when the path: DPP2to DPP2OUT is adopted, the transport resistance is rather large in the vicinity of the main transport roller3-1. In view of this, a path configuration with a path buffer SD is adopted, in which at the position where recording medium P is conveyed to the duplex transport path by the main transport roller pair3, a path DPP2IN is taken and in which after the trailing end of the recording medium has left the main transport roller pair3, a path DPP2OUT is taken. That is, as shown inFIG. 16, the space SD between the inner guide and the outer guide of the duplex transport path is made sufficiently large. Then, due to the rigidity of the recording medium, when entering the duplex transport path, the path DPP2IN is taken, and, after the trailing end of the recording medium has left the main transport roller pair3, the path DPP2OUT is taken. Further, to bring the U-turn transport path and the duplex transport resistance closer to each other, a duplex transport roller101is preferably provided between the main transport roller3-1and the first U-turn transport roller21, thereby canceling the transport resistance generated on the upstream side of the duplex transport roller101.

FIG. 19is a sectional view showing how a thick recording medium, such as a CD or a DVD, is transported. As shown inFIG. 19, with the paper guide flapper24lowered, the main transport roller3-1is reversed, whereby the transport tray54with a CD, a DVD or the like placed thereon is transported from the recording medium ejection side. Due to the rigidity of the transport tray54, the paper guide109suspended by a spring (not shown) is pushed down, and the transport tray is caused to pass the portion below the guide portion108bof the U-turn transport unit casing108and the portion below the second U-turn transport roller22, and is transported to a position in the vicinity of the paper guide106.

Next, the drive row from the drive motor to the U-turn transport roller will be described with reference toFIG. 20. The output of the drive motor39is transmitted to a wheel gear202through a transmission belt201from a motor pulley (not shown) press-fitted onto the output shaft39a, and is further transmitted to U-turn transport roller gears203and204respectively press-fitted onto the U-turn transport rollers21and22. The driving force of the U-turn transport roller gear204is transmitted through an idle gear205to a duplex transport roller gear206arranged on the shaft of the duplex transport roller101. That is, when the drive motor39rotates in the direction MCCW, the U-turn transport rollers21and22and the duplex transport roller101are all rotated in the direction RCW, in which the recording medium is transported. When the drive motor39is rotated in the reverse direction, the U-turn transport rollers21and22and the duplex transport roller101are also rotated in the reverse direction. A code wheel207, which has printed thereon slits for detecting the recording medium transporting amount, that is, the rotating amount of the U-turn transport rollers21and22, is press-fitted, upon accurate positioning, to the wheel gear202situated on the upstream side of the U-turn transport roller gears203and204press-fitted onto the U-turn transport rollers21and22. Then, the slits caused to pass by the rotation of the code wheel207are detected by an encoder sensor208. The drive motor39is feedback-controlled based on an output signal of the encoder sensor208, thereby controlling the rotation of the U-turn transport rollers21and22and the duplex transport roller101, that is, the transport amount of the recording medium.

Next, the operation of feeding sheets from the sheet feeding cassette5will be described with reference toFIGS. 21A and 21BandFIGS. 22A through 22C.FIGS. 21A and 21Bare diagrams illustrating the drive system, andFIGS. 22A through 22Care diagrams illustrating how the recording medium is transported.

InFIGS. 21A and 21B, a transport roller output gear301arranged on the shaft of the second U-turn transport roller22constitutes a sun gear, and driving force is transmitted to a U-turn sheet feeding roller gear304, arranged on the shaft of the U-turn sheet feeding roller6, by means of a swing arm302, a planetary gear303, and a friction spring (not shown). Here, reference numeral309indicates a controlling unit for ON/OFF-controlling the locking of the rotation of the swing arm302; it is connected in driving to the transport roller output gear301. Depending on the rotating direction and the rotating amount of the drive motor39, an opening309aappears or disappears. Only when a lever portion302aof the swing arm302is situated at the opening309a, it is possible for the planetary gear303and the U-turn sheet feeding roller gear304to be meshed with each other. This state is attained during the sheet feeding operation by the U-turn sheet feeding roller6.

The U-turn sheet feeding roller gear304is equipped with a cam surface304aadapted to lower an arm310for pushing up the middle plate37of the sheet feeding cassette5; through balancing with a spring (not shown) pushing up the arm310, the operations of raising and lowering the middle plate37are controlled by the rotation of the U-turn sheet feeding roller gear304. Also on the opposite side of the U-turn sheet feeding roller6, there is arranged a cam2309similar to that of the U-turn sheet feeding roller gear2404, controlling the rising/lowering motion of the arm310and the middle plate37from the right and left sides with the same timing.

InFIG. 22A, the separation roller38is equipped with a torque limiter (not shown) so as to allow rotation in one direction only, and is rotatably mounted to a separation roller holder104. Using a rotation center104aas a fulcrum, the separation roller holder104is brought into and out of contact with the U-turn sheet feeding roller6. The separation roller holder104is controlled to be brought into and out of contact with the U-turn sheet feeding roller6by means of a control gear305in mesh with the U-turn sheet feeding roller gear2404. Further, by a cam (not shown) provided on the U-turn sheet feeding roller6, a cam follower provided on the duplex transport flapper110is raised and lowered, whereby the duplex transport flapper110is raised and lowered around the rotation shaft110awith the motion of the U-turn sheet feeding roller6.

When the sheet feeding operation is started, the state of the drive system is changed from that shown inFIG. 22Ato that shown inFIG. 22B. The middle plate37, the separation roller38, and the duplex transport flapper110are raised by the above-described mechanism. As a result, the recording medium P in the sheet feeding cassette5is fed by the U-turn sheet feeding roller3. When the rotation of the drive motor309is continued, and the separation of the recording medium is completed, the drive system is brought into the state as shown inFIG. 21B. Here, the U-turn sheet feeding roller gear304has an untoothed portion304b. When the untoothed portion304bcomes to a position where it is opposed to the planetary gear303, the rotation of the U-turn sheet feeding roller gear304stops, and exclusively the U-turn transport rollers21and22and the duplex transport roller101rotate, and transport after sheet feeding and printing by the recording head are performed. At this time, the state in which the recording medium is transported has been changed to that shown inFIG. 22C. The separation roller38is placed away from the transport path, and does not come into contact with the recording medium except during sheet feeding operation, so that it does not constitute a resistance to transport. Further, the duplex transport flapper110is kept raised during both sheet feeding and U-turn transport, and continues transport. This helps to prevent defective feeding or skew feed due to transport resistance attributable to the influence of the weight of the duplex transport flapper110.

Further, the U-turn sheet feeding roller6has a semicircular configuration; after the feeding of the recording medium P, the clearance portion of the semicircular roller is opposed to the recording medium. Due to this construction, the transport path is secured, and the transport of the recording medium P by the U-turn transport rollers21and22is not hindered. Thus, it is only necessary for the U-turn sheet feeding roller6to be endowed with a sheet transport performance, and the transport accuracy required of it is not so high.

Next, when the transport is completed, the drive motor39is rotated in the reverse direction in the state shown inFIG. 21B. A transport roller output gear306arranged on the shaft of the U-turn transport roller21constitutes a sun gear, and driving force is transmitted to a control gear305by a swing arm307, a planetary gear308, a friction gear (not shown), and a planetary gear2408. The control gear305has an untoothed portion305a, and is rotated until the planetary gear308comes to a position where it is opposed to the untoothed portion305a. Further, the U-turn sheet feeding roller gear304also rotates, and the untoothed portion304ais removed from the position where it is opposed to the planetary gear303, so that sheet feeding operation is again possible through the next normal rotation of the drive motor39(i.e., the drive system is restored to the state as shown inFIG. 21A). Here, through cam operation due to the rotation of the U-turn sheet feeding roller gear304, the duplex transport flapper110is lowered, making it possible to secure the duplex transport path (i.e., the drive system is restored to the state as shown inFIG. 22A). In this state also, due to the semicircular clearance portion of the U-turn sheet feeding roller6, the U-turn transport path and the duplex transport path are secured.

Due to the above construction, despite the fact that the U-turn sheet feeding roller6and the separation roller38are situated in the duplex transport path, they do not come into contact with the recording medium during U-turn transport and duplex transport except during U-turn sheet feeding operation due to the semicircular configuration of the U-turn sheet feeding roller6and the movement of the separation roller38away from the transport path. Thus, even if the printing ink on the surface has not been dried yet, there is no fear of ink, etc. being transferred to the U-turn sheet feeding roller6. Further, it is possible to suppress wear of the U-turn sheet feeding roller6.

Next, the duplex transport will be described with reference toFIGS. 23A and 23B.

As shown inFIG. 23A, after the completion of printing on the obverse side of a recording medium, the paper guide flapper24is raised by a switching mechanism (not shown) to secure the entrance to the duplex transport path. Then, by rotating the main transport roller3-1in the reverse direction, the recording medium P the obverse side of which has undergone printing is transported to the duplex transport path below. At this time, the drive motor39is also rotated in synchronism therewith, whereby the recording medium is transported to the duplex transport roller101and the U-turn transport rollers21and22. The second detection lever113, arranged between the duplex transport roller101and the U-turn transport roller21, detects whether the recording medium P is being transported or not.

Here, when the passage of the recording medium P cannot be detected by the second detection sensor114, a paper jamming error display is given, calling attention for the necessity of removing the jammed recording medium. As the anti-jamming means, the sheet feeding cassette5is drawn out, and the paper guide103is opened in the direction JA, whereby the press contact of the two-side pinch roller102with the duplex transport roller101is canceled, making it possible to remove the jammed recording medium P. The paper guide103is suspended up above by a spring (not shown), and, when released by the user, returns to the original position, where it does not hinder the insertion of the cassette. In this way, a jam processing opening that can be opened and closed is provided between the sheet feeding cassette and the duplex transport path, whereby jamming can be coped with without using any such large-scale jam processing mechanism as would cause attachment/detachment of roller and units.

Next, when, as shown inFIG. 23B, the leading end of the recording medium P having passed the second U-turn transport roller22is detected by the second detection lever111, the trailing end of the recording medium P has already passed the main transport roller pair3. Then, the paper guide flapper24is lowered by a switching mechanism (not shown), and the main transport roller pair3is switched from reverse to normal rotation, causing the U-turn transport rollers21and22and the duplex transport roller101to make normal rotation, whereby the recording medium P is transported to the main transport roller pair3and printing becomes possible.

At this time, an opening309aof a control ring unit309is closed. A lever portion304aof a swing arm304is obstructed by the control ring unit309, and the U-turn sheet feeding roller6is not driven. In this state, reverse side printing is performed, and the recording medium is ejected. When two-side printing has been completed or when the trailing end of the recording medium has passed the second U-turn transport roller22, the opening309aof the control ring unit309is opened, and the apparatus is made ready for sheet feeding.

Due to the above construction, it is possible to realize, with a simple structure, sheet feeding from the upper portion of the main body, U-turn sheet feeding, duplex transport, and the transport of a thick recording medium, such as a CD or a DVD. Further, this construction allows transport of recording mediums of various sizes, and it is possible to transport with high accuracy a high quality recording medium that does not easily bend even in the case of U-turn sheet feeding or duplex transport.

According to the above embodiments of the present invention, it is possible to provide a recording apparatus that helps to achieve a reduction in size and cost.

This application claims priority from Japanese Patent Application Nos. 2003-382533 filed Nov. 12, 2003 and 2004-238446 filed on Aug. 18, 2004, which are hereby incorporated by reference herein.