JP2017145078A - Printer - Google Patents

Abstract

In a printing apparatus provided with a medium detection apparatus, a printing apparatus capable of suppressing the size dimension of the printing apparatus in the medium width direction is provided. A printing apparatus includes a medium placement unit (a cassette and a feed tray) on which a medium can be placed, a transport unit that transports the medium from the medium placement unit, a print head that prints on the medium, and a print head. And a medium detection device 80 that is arranged on the upstream side in the medium conveyance direction and can detect the side edges on both sides of the medium by reading the medium in the width direction X. The transport unit transports the medium from the medium placement unit along a path that passes through the printable position of the print head, and reverses the medium on which one side is printed by the print head through the transport path 30. And a third feeding path 93 (an example of a double-sided printing path) that returns to a position in the middle of the transport path. The reading position of the medium detection device 80 is located on the upstream side in the transport direction Y with respect to the second path joining portion J2 (an example of the joining portion) between the transport path 30 and the third feeding path 93. [Selection] Figure 6

Description

  The present invention provides a printing apparatus including a conveyance unit that conveys a medium such as paper, a print head that prints on the conveyed medium, and a medium detection device that can detect a side edge in the width direction that intersects the conveyance direction of the medium. Relates to the device.

Conventionally, as an example of this type of printing apparatus, a printing apparatus having a conveyance unit that conveys a medium such as paper and a print head that prints on the medium is widely known (for example, Patent Document 1).
For example, Patent Document 1 discloses a serial printing apparatus including a paper width detection device (an example of a medium detection device) that detects the width of a paper at a position upstream of a printing unit in the conveyance direction of the paper (an example of a medium). (Serial printer) is disclosed. The printing apparatus includes a carriage having a print head that performs printing by moving in a paper width direction (main scanning direction) orthogonal to the paper conveyance direction by driving a motor, and a position upstream of the print head in the conveyance direction in the carriage. Two sensors (a right detector and a left detector) are provided. As the carriage moves in the paper width direction, the right detector detects the right edge of the paper, and the left detector detects the left edge of the paper.

JP 2001-287405 A

  By the way, the paper width detection device described in Patent Document 1 is provided in a carriage that can be moved in the main scanning direction for printing on a serial printing type printing device. For example, a line printing type printing device (line printer) In a printing apparatus that does not include a printing carriage, a configuration in which a sensor is provided on the printing carriage cannot be employed. Further, when a device that can detect both side edges of the maximum width medium assumed in the printing apparatus is separately assembled, there is a problem that the size of the printing apparatus in the transport direction may be increased. Note that this type of problem can be avoided when the configuration in which the printing carriage is provided with a sensor as in Patent Document 1 is to be avoided in order to prevent a decrease in detection accuracy due to the sensor being stained with ink. This is also generally common to printing-type printing apparatuses.

  An object of the present invention is to detect the side edges on both sides in the width direction of a medium without depending on the printing method whether or not the print head moves, and to keep the size dimension of the apparatus in the transport direction relatively short. It is an object of the present invention to provide a printing apparatus that can perform such a process.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A printing apparatus that solves the above problems includes a medium placement unit that can place a medium, a transport unit that transports a medium from the medium placement unit, a print head that prints on the medium, and the print head that is more than the print head. A medium detection device that is arranged upstream of the medium conveyance direction and that can detect the side edges on both sides of the medium by reading the medium in a width direction that intersects the conveyance direction; A transport path for transporting the medium from the medium placement section through a path that passes through the printable position of the print head, and a medium on one surface of which is printed by the print head through the transport path. A double-sided printing path that is reversed in a printable direction and returned to a joining portion located upstream of the print head in the transport path in the transport direction, and the reading position of the medium detection device is the transport position On the route Than the merging portion of the kicking the duplex print path located upstream of the transport direction.

  According to this configuration, the medium detection device is disposed at a position where the reading position is upstream in the transport direction with respect to the junction with the duplex printing path in the transport path. Therefore, although the medium detection device is provided, the size of the printing device in the transport direction can be made relatively short. For example, if it is attempted to adopt a configuration in which the medium detection device also reads the medium on which one surface returned through the duplex printing path is printed, the joining portion is shifted to the upstream side in the transport direction from the reading position of the medium detection device. Accordingly, it is necessary to shift a portion located upstream of the junction of the duplex printing path and the transport path to the upstream side in the transport direction. In this case, the size in the transport direction of the printing apparatus becomes relatively long by the amount of the shift. On the other hand, if the medium on which one side is printed is not read, and the merging portion can be arranged downstream of the reading position in the conveying direction, it is positioned upstream of the merging portion in the conveying path and the duplex printing path. It becomes possible to arrange the portion as close to the downstream side as possible. Therefore, the medium detection device separate from the print head can detect both side edges in the width direction of the medium without depending on whether the print head is movable or fixed. Although provided, the size of the printing apparatus in the transport direction can be kept relatively short.

  The printing apparatus may further include a cover that can be opened and closed at a position upstream of the print head in the transport direction with respect to the apparatus main body of the printing apparatus, and the cover includes a plurality of the medium mounts. At least a part of a feeding unit capable of feeding a medium placed on at least one of the placement units, a conveyance path for guiding the medium along the conveyance path, and the medium along the duplex printing path. It is preferable that a medium guide member forming at least a part of a passage merging portion where the double-sided printing passage that guides the merging portion to the merging portion is assembled.

  According to this configuration, when the cover is opened, at least a part of the feeding unit capable of feeding the medium placed on the at least one medium placing unit and at least a part of the passage merging unit are formed. The medium guide member is detached from the apparatus main body together with the cover. For this reason, when the cover is opened, a part of the medium detection device is exposed, and maintenance of the medium detection device is facilitated. Further, for example, when it is necessary to remove the medium detection device, the medium detection device can be removed relatively easily.

  In the printing apparatus, a plurality of the medium placement units are provided, and the first merge unit where at least two feeding paths through which the medium is fed from different medium placement units merges is the merge unit. The second merging section is positioned upstream of the second merging section, and the reading position is located downstream of the first merging section and upstream of the second merging section in the conveying direction. Is preferred.

  According to this configuration, since the reading position is located downstream of the first merging unit and upstream of the second merging unit in the transport direction, the reading position is placed on any of the plurality of medium placement units. A medium fed through any one of at least two feeding paths can be commonly read by a single medium detecting device at a reading position and the side edge thereof can be detected.

  Further, in the above-described printing apparatus, the reading position is downstream in the transport direction from the first path joining portion where at least two feeding paths of the medium fed through the at least two feeding paths merge. It is preferable to be located at.

  According to this configuration, since the reading position is located on the downstream side in the transport direction with respect to the first path merging unit where at least two feeding paths of the media fed from different medium placing units merge, at least 2 is provided. The medium fed through any one of the two feeding paths can be read at a substantially constant distance by one common medium detection device. Therefore, the medium fed through any of the feeding paths from the medium placing unit can be read with relatively high accuracy, and higher side edge detection accuracy can be ensured.

  In the above-described printing apparatus, the reading position of the medium detection device includes a conveyance path that guides the medium along the conveyance path, and a double-sided printing path that guides the medium to the merging unit along the double-sided printing path. It is preferable that it is located in the upstream of the said conveyance direction rather than the channel | path confluence | merging part to which merging. The medium conveyance path and the double-sided printing path are paths that respectively pass through the conveyance path and the double-sided printing path, and therefore, the path merging portion is located on the upstream side in the conveyance direction with respect to the merging portion of the path.

  According to this configuration, since the reading position is located on the upstream side in the transport direction with respect to the double-sided printing path in the transport path, in addition to the above-described effects, the print position applied to one surface is further increased. Ink hardly adheres to the periphery of the reading position of the medium detection device. Therefore, it is easy to suppress a decrease in side edge detection accuracy due to ink stains around the reading position of the medium detection device.

  Further, in the printing apparatus, the medium detection device includes a carriage that is movable in the width direction at a position upstream of the print head in the transport direction, a sensor provided on the carriage, and the carriage that is the sensor. Is preferably provided with a power source that moves side edges on both sides of the medium having the maximum width within a detectable moving range.

  According to this configuration, the medium detection device has a shape that is slightly longer in the width direction than the width of the maximum width medium in which the carriage can move in the moving range in which the sensor can detect the side edges on both sides in the width direction of the maximum width medium. Even if the medium detection device is provided, the size of the printing device in the conveyance direction can be reduced by arranging the medium detection device on the upstream side in the conveyance direction from the merging portion (second merging portion). It can be made relatively short.

  In the printing apparatus, the carriage is provided movably in the width direction at a position opposite to the print head side with respect to a conveyance path of a medium conveyed by the conveyance unit, and the sensor It is preferable that the optical sensor be capable of reading the medium from a position opposite to the print head side with respect to the transport path.

  According to this configuration, since the optical sensor moves in the width direction together with the carriage at a position opposite to the print head side with respect to the transport path of the medium transported by the transport section, the medium is read in the width direction. The side edge of the medium can be detected. At this time, the sensor is protected by the medium from ink mist from the print head.

  Furthermore, in the printing apparatus, the medium detection device includes a housing that houses the carriage and the optical sensor, and the housing is transported from the medium mounting portion to a portion facing the transport path. A medium supporting portion for supporting the medium, and the medium supporting portion is provided with a light transmissive window in a region corresponding to a movement path of the optical sensor accompanying the movement of the carriage. preferable.

  According to this configuration, since the carriage and the sensor are housed in the housing, the sensor can be protected from paper dust that has come out of the medium, ink mist that has come out of the print head, and the like. In addition, the medium transported from the medium placement unit can be supported by the medium support unit of the casing of the medium detection device, and the medium supported by the medium support unit is transported by the sensor through the light-transmitting window. The side edge can be detected by reading through. As a result, it is easy to avoid a decrease in detection accuracy due to sensor paper dust and ink mist stains, and it is easy to keep the distance between the sensor and the medium supported by the medium support part including the window part substantially constant, From this point, the detection accuracy of the sensor can be increased.

  In the printing apparatus, the sensor is a light reflection sensor, and a medium guide member that guides the medium along the transport path is disposed at a position facing the movement path of the sensor across the transport path. The medium guide member preferably has a light reflecting surface at a portion facing the movement path of the sensor.

  According to this structure, the part which opposes the movement path | route of the sensor in the medium guide member which opposes a window part is a light reflection surface. For this reason, it is not necessary to separately provide a member dedicated to the light reflecting surface. Therefore, the medium guide structure of the transport unit can be configured relatively compactly.

  In the printing apparatus, the medium placement unit may include both or one of a cassette capable of accommodating a plurality of media in a stacked state and a feeding tray capable of placing one or a plurality of media. It is preferable that

  According to this configuration, the medium detection device can detect the side edge of the medium conveyed from both or one of the cassette and the feeding tray while reducing the size of the printing apparatus in the conveyance direction.

1 is a perspective view illustrating a printing apparatus according to an embodiment. 1 is a schematic cross-sectional view of a printing apparatus. The perspective view of the printing apparatus in the state which opened the cover. The perspective view which shows the main body side feeding mechanism part and the cover side feeding mechanism part in the state which opened the cover. The sectional side view which shows a feeding mechanism. The sectional side view which shows a part of feeding mechanism. The sectional side view which shows the main body side feeding mechanism part and the cover side feeding mechanism part in the state which opened the cover. The perspective view which shows a medium detection apparatus and its peripheral part. The perspective view which shows a medium detection apparatus. The disassembled perspective view which shows a medium detection apparatus. The top view which shows the state which removed the cover of the medium detection apparatus. The perspective view which looked at the medium detection apparatus from the back side. The top view which shows the carriage in the state in a home position. FIG. 14 is a cross-sectional view taken along line 14-14 in FIG. 13 showing the main part of the medium detection device. FIG. 15 is a cross-sectional view taken along line 15-15 in FIG. 13 showing the main part of the medium detection device. FIG. 2 is a block diagram illustrating an electrical configuration of the printing apparatus. FIG. 5 is a schematic plan view for explaining medium side edge detection processing in the medium detection device. The signal waveform diagram of each sensor explaining the side edge detection process of a small-sized medium. The signal waveform diagram of each sensor explaining the side edge detection process of a large-sized medium. 7 is a flowchart illustrating a medium side edge detection processing routine. 7 is a flowchart showing a medium side edge detection processing routine at the time of failure.

Hereinafter, an embodiment of a printing apparatus will be described with reference to the drawings.
As shown in FIG. 1, the printing apparatus 11 includes a printer unit 12 having a printing function for printing on a medium P such as paper, and a scanner unit 13 disposed on the upper side of the printer unit 12. It consists of a multi-function machine that has a substantially rectangular parallelepiped shape. An operation panel 14 is provided on the upper surface of the printer unit 12 at a position next to the scanner unit 13 (front side in FIG. 1). The operation panel 14 includes a display unit 15 having a touch panel function, for example. In this example, the touch panel constitutes an example of the operation unit 16. The operation unit 16 may be an operation switch.

  As shown in FIG. 1, the scanner unit 13 includes a scanner body unit 17 whose upper surface is a document table (not shown), and a document that is openable and closable with respect to the upper surface (document table glass surface) of the scanner body unit 17. And a base cover 18. An automatic document feeder 19 (auto document feeder (ADF)) is mounted on the document table cover 18.

  The scanner unit 13 includes a reading unit (not illustrated) that opens a document table cover 18 and reads a document set on a document table glass (not illustrated). The automatic document feeder 19 sequentially feeds a plurality of documents set on the placing table 19A one by one, and the documents scanned by the reading unit are sequentially discharged onto the stack unit 19B. The printing apparatus 11 configured as described above includes a main body 20 having a substantially rectangular parallelepiped shape having the above-described document table and the operation panel 14 on an upper surface portion, and a document table cover 18.

  As shown in FIG. 1, in a lower part of the printer unit 12, a cassette 21 that can store and store a plurality of media P in a stacked state can be inserted into and removed from the main body 20 from the front side. A plurality of stages are inserted. A feeding tray 22 is provided at one side of the main body 20 so as to be openable and closable around the lower end. The feeding tray 22 is in an open state indicated by a two-dot chain line in FIG. 1, and a medium P to be printed can be set thereon. Further, a maintenance cover 23 including a feeding tray 22 and a maintenance cover 24 disposed below the cover 23 are laterally arranged around one side end on one side of the main body 20. It is provided so that it can be opened and closed. In the present embodiment, the cassette 21 and the feeding tray 22 constitute an example of a medium placement unit. The feed tray 22 may be a manual feed tray on which only one medium P can be set, or a structure with a hopper function that can set a plurality of media in a stacked state and can automatically feed one by one.

  In the printer unit 12, the part above the cassette 21 is a printing mechanism unit 25 (see FIG. 2) that prints on the medium P fed from the cassette 21 or the feeding tray 22. A stacker unit 26 is provided between the printer unit 12 and the scanner body unit 17 for discharging the printed medium.

  Next, a detailed configuration of the printer unit 12 will be described with reference to FIG. In FIG. 2, the cassette 21 shows only the uppermost one, and other cassettes are omitted. A direction in which the medium P is transported when printing on the print head 34 is defined as a transport direction Y, and a direction intersecting (particularly orthogonal) with the transport direction Y is defined as a width direction X.

  As shown in FIG. 2, the above-described printing mechanism unit 25 is provided in the main body 20 of the printing apparatus 11 of the present embodiment. The printing mechanism unit 25 includes a transport unit 32 as an example of a transport unit that transports the medium P along the transport path 31, and a print unit 33 having a print head 34 that prints on the medium P being transported. .

  The print head 34 employs an ink jet system that ejects ink. The print head 34 is a long line head extending slightly longer than the width of the medium P having the maximum width in the width direction X orthogonal to the paper surface of FIG. 1 and cannot be moved in the width direction X and is fixed at a predetermined position. Fixed type. In the present embodiment, a line printing system in which printing is performed in a line by ejecting ink droplets all at once in a range in the width direction X with respect to the medium P being conveyed by the print head 34 formed of a fixed line head. Is adopted. As the ink ejected from the print head 34 adheres to the medium P, an image, a document, or the like is printed on the medium P. The printing unit 33 includes a printing carriage that can move in the width direction X, and the print head 34 provided on the printing carriage moves in the width direction X (main scanning direction) together with the printing carriage. It is also possible to adopt a serial printing method that is movable and in which the conveying operation of the medium P and the printing operation by the print head 34 are alternately performed.

  As shown in FIG. 2, the transport unit 32 includes a feeding mechanism unit 35 that feeds the medium P, and a transport mechanism unit that transports the medium P along the transport path 36 when the printing unit 33 performs printing. 37 and a discharge mechanism unit 38 that conveys the printed medium P along the discharge path 62 and discharges the medium P to the stacker unit 26.

  The feeding mechanism unit 35 has finished the first feeding unit 41 having the feeding tray 22 as the feeding source, the second feeding unit 42 having the cassette 21 as the feeding source, and printing on one side during duplex printing. And a third feeding unit 43 that feeds the medium P to the transport path 36 again. The first feeding unit 41 sets the medium P, which is set on the feeding tray 22 and has the leading end inserted through the insertion port 20A, to the first feeding path by the rotation of the first feeding roller pair 44. Then, the sheet is fed along the line 45 to the transport mechanism unit 37. Note that the cover 23 (see FIGS. 1 and 3) provided with the feeding tray 22 is provided to be openable and closable at a position upstream of the print head 34 in the main body 20 in the transport direction Y.

  Further, the second feeding unit 42 feeds the medium P from the cassette 21 along the second feeding path 48. The second feeding unit 42 includes a pickup roller 49 that feeds the uppermost medium P in the cassette 21, a separation roller pair 50 that separates the fed medium P into one sheet, and one separated medium P A second feeding roller pair 51 and a driven roller 52 for feeding are provided.

  As shown in FIG. 2, the transport mechanism unit 37 includes a transport roller pair 46 disposed at a position slightly downstream in the transport direction Y with respect to the junctions of the first to third feeding units 41 to 43, and a print head. 34 and a belt conveyance mechanism 58 disposed at a position facing the line 34. The medium P is skewed in the feeding process by abutting the leading end against the stopped conveying roller pair 46, and the skewed medium P is conveyed to the conveying path 36 by the rotation of the conveying roller pair 46.

  The belt transport mechanism 58 includes a pair of rollers 59 and 60 and a transport belt 61 wound around the pair of rollers 59 and 60. Further, a transport driven roller 47 that is driven in contact with the transport belt 61 is disposed above the roller 59 of the belt transport mechanism 58. The belt conveyance mechanism 58 employs an electrostatic adsorption method in which the medium P is adsorbed to the surface of the charged conveyance belt 61 by electrostatic force. The print head 34 ejects ink toward the medium P transported at a constant speed while maintaining a constant gap with the print head 34 by the belt transport mechanism 58, whereby an image, a document, or the like is printed on the medium P. The

  The third feeding unit 43 performs re-feeding of the medium P on which one side (one side) has been printed by reversing the front and back and guiding the medium P to the transport mechanism unit 37 again during duplex printing. The medium P on which one surface discharged from the transport mechanism unit 37 has been printed is guided to the branch transport path 54 by the branch mechanism 53, and is rotated in the reverse direction after the forward rotation of the transport roller pair 55 in FIG. It is guided to the reverse feeding path 56 positioned above the position. Then, the medium P is fed along the reverse feeding path 56 by the rotation of the plurality of reverse conveying roller pairs 57 and merged in the inverted state to the first feeding path 45 and the second feeding path 48. Then, the paper is guided again to the transport mechanism unit 37, and the print head 34 performs printing on the other unprinted surface of the inverted medium P, whereby double-sided printing is performed.

  The discharge mechanism unit 38 rotates the plurality of discharge roller pairs 63 arranged along the discharge path 62 so that the medium P after printing is stacked from the medium discharge port 20B as shown by a two-dot chain line in FIG. Drain up. The discharged printed medium P is stacked on the stacker unit 26. Note that the conveyance path 30 conveys the medium P from the cassette 21 and the feeding tray 22 along a path that passes through a position where the print head 34 can print.

  As shown in FIG. 2, a medium detection device 80 is disposed slightly upstream of the transport roller pair 46 positioned upstream of the print head 34 in the transport direction Y. The medium detection device 80 is positioned below the vicinity of the junction between the first feeding path 45 and the second feeding path 48 and the junction between the conveyance path 30 and the reverse feeding path 56. The medium detection device 80 detects a side end in the width direction X that intersects (particularly orthogonally) the conveyance direction Y of the medium P fed by the first feeding unit 41 and the second feeding unit 42. It relates to the width including at least one of the side end position in the width direction X on the medium P, the medium width (medium size) and the print range in the width direction X from the information on the side end of the medium P detected by the medium detection device 80. Media information is acquired.

  Next, with reference to FIGS. 3 to 7, a configuration of a portion including the periphery of the medium detection device 80 in the feeding mechanism unit 35 will be described. 5 and 6 show a state where the cover 23 is closed, and FIG. 7 shows a state where the cover 23 is opened.

  As shown in FIGS. 3 and 4, when the cover 23 that can be opened and closed with respect to the apparatus main body 20 of the printing apparatus 11 is opened, a part of each of the feeding units 41 to 43 is exposed. Each of the feeding units 41 to 43 includes a main body side feeding mechanism unit 65 assembled to a frame (not shown) in the main body 20 and a cover side feeding mechanism unit 66 assembled to the inner surface side of the cover 23. The A medium detection device 80 is assembled on the main body 20 side. The medium detection device 80 detects the side edge of the medium P by reading the medium P in the width direction X through the window 88 on the upper surface while supporting the medium P being fed or conveyed on the upper surface. For this reason, the medium guide portion 81A and the medium support portion 81B that form the upper surface portion that supports the medium P of the medium detection device 80 also constitute a part of the main body side feeding mechanism portion 65.

  As shown in FIGS. 5 and 7, the main body-side feeding mechanism unit 65 includes a separation roller pair 50, a driving roller 51 </ b> A, a guide member 67, and a third feeding unit 43 that constitute the second feeding unit 42. The driving roller 57A, the guide members 68 and 69, the conveyance roller pair 46, and the like are included. In addition, the medium detection device 80 includes a slanted medium guide portion 81A that guides the medium P from the second feeding path 48 in the upstream portion of the upper surface portion of the casing 81 in the transport direction Y. Furthermore, the medium detection device 80 supports the medium P from the first feeding path 45 and the second feeding path 48 on the upper surface portion of the housing 81 that is downstream in the transport direction Y with respect to the medium guiding portion 81A. It has a medium support part 81B. For this reason, the medium guide portion 81 </ b> A and the medium support portion 81 </ b> B constitute a part of the main body side feeding mechanism portion 65.

  As shown in FIGS. 5 and 7, the cover-side feeding mechanism 66 includes a pair of feeding rollers 44, guide members 70 and 71, and a second feeding unit 42 that constitute the first feeding unit 41. The driven rollers 51 </ b> B and 52, the guide member 72, and the driven roller 57 </ b> B configuring the third feeding unit 43 are included. The guide member 71 assembled integrally with the cover 23 has a medium guide surface 71 </ b> A constituting the first feed path 45 and a medium guide surface 71 </ b> B constituting the reverse feed path 56. The cover-side feeding mechanism unit 66 includes a feeding mechanism that feeds the medium P from at least one of the feeding tray 22 and the cassette 21 that constitute an example of a plurality of medium placement units. In this example, examples of the plurality of medium placement units are both the feeding tray 22 and the cassette 21, and the cover 23 includes all of the first feeding unit 41 as an example of at least a part of the feeding unit. A part of the second feeding unit 42 is assembled.

  As shown in FIGS. 5 and 6, the feed roller pair 44 includes a drive roller 44 </ b> A and a driven roller 44 </ b> B. A part of the first feeding path 45 is formed by arranging the guide member 70 and the medium guide surface 71A of the guide member 71 facing each other on the downstream side in the feeding direction of both rollers 44A and 44B. Has been. A part of the second feeding path 48 is formed by the guide members 67 and 72 facing each other and the medium guide portion 81A of the medium detection device 80.

As shown in FIG. 5, the separation roller pair 50 constituting the second feeding unit 42 includes a driving roller 50 </ b> A and a driven roller 50 </ b> B.
As shown in FIGS. 5 and 6, the pair of reverse conveying rollers 57 constituting the third feeding unit 43 includes a driving roller 57 </ b> A and a driven roller 57 </ b> B. The downstream portion of the reverse feeding path 56 that feeds the medium P on which one side has been printed by being reversed is formed by a guide member 68 on the main body 20 side and a guide member 71 on the cover 23 side that are arranged to face each other. Has been. Further, the surface of the medium detection device 80 facing the guide member 68 also forms a part of the reverse feeding path 56. Further, the transport roller pair 46 disposed at a position downstream of the medium detection device 80 in the transport direction Y includes a drive roller 46A and a driven roller 46B.

  The driving roller 44A shown in FIG. 5 is driven by the power of the first feeding motor 121 (see FIG. 16). The drive rollers 50A and 51A are driven by the power of the second feeding motor 122 (see FIG. 16). The driving roller 46A and the driving roller 57A are driven by the power of the first transport motor 123 (see FIG. 16). 2 is driven by the power of the belt motor 124 (see FIG. 16). 2 is driven by the power of the second transport motor 125 (see FIG. 16).

  As shown in FIG. 6, the first feeding path 45 and the second feeding path 48 merge at the first junction 75. On the downstream side of the first merging portion 75 in the feeding direction (conveying direction Y), a second feeding path 48 as an example of a conveying path and a reverse feeding path 56 as an example of a duplex printing path are merged. And a second merging portion 76 as an example of a passage merging portion. That is, the first feeding path between the first joining section 75 and the second joining section 76 is a common feeding path for the medium P fed from the feeding tray 22 and the medium P fed from the cassette 21. A common feeding path 77 is provided. In order to perform duplex printing on the downstream side in the feeding direction (conveying direction Y) with respect to the medium P before printing, which is fed to print one surface of the medium P, with respect to the second joining unit 76. The second common feeding path 78 is a common feeding path with the printed medium P that is fed again for printing on one side after printing on one side. Thus, on the upstream side in the transport direction Y from the print head 34 (see FIG. 2), the first feeding path 45, the second feeding path 48, and the first common feeding path that constitute an example of the single-side printing path. 77 and a second merging portion 76 that is a merging portion of the reverse feeding path 56 exists.

  As shown in FIG. 6, the plurality of medium guide surfaces that form the second joining portion 76 form a reverse feeding path 56, a downstream portion of the two medium guide surfaces 71 </ b> A and 71 </ b> B of the guide member 71. This is the surface of the downstream portion of the medium guide surface 68A and the portion slightly downstream of the medium support portion 81B of the medium detection device 80. A portion (merging region) where the media P merge is formed by these surfaces. The guide member 71 assembled to the cover 23 (see FIGS. 5 and 7) has a part of medium guide surfaces 71A and 71B forming the second joining portion 76. In particular, the second joining portion 76 is formed by a location where the two medium guide surfaces 71A and 71B of the guide member 71 intersect.

  As shown in FIGS. 5 and 6, the medium detection device 80 is disposed below the first joining portion 75 and the second joining portion 76. The upper surface portion of the casing 81 of the medium detection device 80 constitutes a part of the second feeding path 48, the first common feeding path 77, and the second common feeding path 78. Further, a sensor 79 capable of detecting an end portion of the medium P in the transport direction Y is provided upstream of the transport roller pair 46 in the transport direction Y. The sensor 79 is used to detect the leading end of the medium P in the transport direction Y and determine the timing of the skew removal operation of the medium P by the transport roller pair 46.

  As shown in FIG. 6, the medium detection device 80 includes the above-described casing 81, a carriage 82 accommodated in the casing 81 so as to be movable in the width direction X (the orthogonal direction in FIG. 6), A sensor 83 provided on the side facing the conveyance path 30 and an electric motor 103 (see FIGS. 12 and 16) as an example of a power source for moving the carriage 82 are provided. A pair of rail portions 84 and 85 for guiding the carriage 82 to be movable along the width direction X are provided in the housing 81. The carriage 82 is fixed to a part of an endless belt 87 wound around a plurality of pulleys 86 (only one is shown in FIG. 6). The medium detection device 80 employs a belt drive system in which the carriage 82 is reciprocated in the width direction X by the rotation of the belt 87 by the power of the electric motor 103. Thus, since the medium detection device 80 is provided separately from the print head 34, the carriage 82 and the sensor 83 can move in the width direction X independently of the print head 34 (see FIG. 2).

  As shown in FIG. 6, the casing 81 of the medium detection device 80 is provided with a window portion 88 made of a light transmitting member at a portion facing the detection direction side of the sensor 83 when the carriage 82 moves. The light transmitting member constituting the window 88 is made of a transparent member such as transparent glass or transparent plastic. The sensor 83 in this example is an optical sensor, and the side end in the width direction X of the medium P is optically read through the window 88 of the medium P fed through the first common feeding path 77. To detect. The carriage 82 is movable in the width direction X at a position upstream of the print head 34 in the transport direction Y. Therefore, the sensor 83 can detect the side edge of the medium P at a position upstream of the print head 34 in the transport direction Y. Therefore, the side edge position of the medium P detected in advance by the medium detection device 80 can be used for controlling the print head 34 that performs printing at a position downstream of the position.

  As shown in FIG. 6, in the area where the sensor 83 faces in the detection direction (light emission direction) through the window 88, that is, the facing area corresponding to the reading position, one of the medium guiding surfaces 71A of the guide member 71 is provided. The portion extends horizontally in a state parallel to the window 88 in the transport direction Y and parallel to the movement path of the sensor 83 in the width direction X. That is, a part of the medium guide surface 71A is a horizontal plane that can maintain the same distance from the sensor 83 at any position on the movement path of the sensor 83. Then, at least a region facing the movement path of the sensor 83 in the horizontal portion of the medium guiding surface 71A is a light reflecting surface 71C that reflects light from the sensor 83. In this example, the guide member 71 is made of metal, and the light reflecting surface 71C has a mirror-finished portion of the medium guide surface 71A of the guide member 71, for example, polished or plated.

  The light reflection surface 71C is formed to have a light reflectance sufficiently higher than that of the medium P, and the light reflection sensor 83 receives the reflected light from the light reflection surface 71C and has a detection voltage value corresponding to the amount of light received. When the threshold value is exceeded, the L level is output, and when the reflected light from the medium P is received and the detection voltage value corresponding to the received light amount is equal to or less than the threshold value, the H level is output (see FIGS. 18 and 19). ). That is, the sensor 83 outputs an L level when the medium P is not detected, and outputs an H level when the medium P is detected. Note that it is only necessary that the sensor 83 can output a detection signal according to the presence or absence of the medium P. For example, the light reflecting surface 71C is sufficiently less reflective than the medium P by coating or roughening the light reflecting surface 71C. It may be a rate.

  As shown in FIG. 6, a part of the second feeding path 48 is formed by the oblique medium guide portion 81 </ b> A on the upper surface portion of the casing 81 of the medium detection device 80. Further, the medium P fed from the feeding tray 22 and the cassette 21 by the window 88 and the medium guide part 81C positioned on the downstream side in the transport direction Y with respect to the window 88 in the upper surface of the casing 81. The medium support part 81B is supported in common. The medium detection device 80 has an extending part 81D that extends from the upper part of the housing 81 to the downstream side in the transport direction Y. The extending portion 81D is disposed at a position facing the guide member 69, which is a part of the support member that supports the driven roller 46B, and forms a part of the second common feed path 78.

  As shown in FIG. 6, the carriage 82 is provided so as to be movable in the width direction X at a position opposite to the print head 34 side with respect to the transport path 30 of the medium P transported by the transport unit 32. The sensor 83 can detect the side edge of the medium P by irradiating light toward the medium P from a position opposite to the print head 34 side across the conveyance path 30.

  As shown in FIG. 6, the medium detection device 80 has a reading position of the sensor 83 (a broken line position in FIG. 6) from the second merging unit 76 where the first common feeding path 77 and the reverse feeding path 56 merge. Is also arranged at a position on the upstream side in the transport direction Y. For example, if the medium detection device 80 is to be arranged at a position where one side of the printed medium P can be read, the second joining unit 76 is arranged to be shifted upstream of the reading position of the medium detection device 80 in the transport direction. Accordingly, the third feeding unit 43 and the first feeding unit 41 having the reverse feeding path 56 need to be shifted to the upstream side in the transport direction Y. In this case, it is necessary to arrange the feeding mechanism unit 35 of the printing apparatus 11 at a position retracted to the upstream side in the conveyance direction Y, and the size dimension of the printing apparatus 11 in the conveyance direction Y is relative to that amount. The printing apparatus 11 becomes larger in the transport direction Y.

  In contrast, the side edge of the medium P on which one surface is printed is not read, and the second path junction portion J2 is arranged at a position downstream of the reading position with respect to the medium detection device 80. This eliminates the need for the first feeding unit 41 and the third feeding unit 43 to be shifted to the upstream side in the transport direction Y. In this way, the size of the printing apparatus 11 in the transport direction Y is relatively shortened.

  Further, as shown in FIG. 6, the medium P fed along the first feeding path 91 that is the path of the medium P fed by the rotation of the feeding roller pair 44 and the second feeding path 48. The second feeding path 92, which is the first path, joins at the first path joining portion J1 located slightly downstream of the first joining portion 75. Further, the second feeding path 92 has a third feeding path 93 as an example of a double-sided printing path that is a path of the medium P fed along the reverse feeding path 56 rather than the second merging unit 76. It merges in the 2nd path | route merge part J2 as an example of the merge part located a little downstream. The reading position of the medium detection device 80 is located on the upstream side in the transport direction Y with respect to the second path joining portion J2. In addition, the reading position of the medium detection device 80 is located on the downstream side in the transport direction Y from the first path junction portion J1. The position range of the reading position is a portion on the upstream side of the second path junction portion J2 in the common transport path through which the media P fed from the cassette 21 and the feed tray 22 are transported in common. Yes. For this reason, the side edge can be detected by reading the medium P while maintaining a substantially constant distance from the sensor 83 regardless of which feeding source (medium loading unit) the medium P is. Thus, it is easy to avoid the printing ink applied to one surface of the medium P fed through the reverse feeding path 56 from adhering to the window 88. Therefore, a decrease in detection accuracy and erroneous detection of the side edge of the medium P due to variations in the distance between the sensor 83 and the medium P at the reading position and ink stains on the window 88 are reduced.

  In the present embodiment, the reading position of the medium detection device 80 may be on the upstream side in the transport direction Y with respect to the second path joining portion J2. In addition, the reading position is preferably on the upstream side in the transport direction Y with respect to the second junction 76. Furthermore, the reading position of the medium detection device 80 may be on the downstream side in the transport direction Y with respect to the first joining portion 75. In addition, the reading position is preferably on the downstream side in the transport direction Y from the first path junction portion J1.

  If the reading position is at a position upstream of the second junction 76, the guide member 71 having the two medium guide surfaces 71 </ b> A and 71 </ b> B forming the second junction 76 is moved by the sensor 83. Located opposite to. In this example, a light reflecting surface 71C that reflects light from the sensor 83 is formed in a region of the guide member 71 that faces the sensor 83, and the medium guiding member and the light reflecting surface member are shared. Is planned.

  As shown in FIG. 7, when the cover 23 is opened, the cover-side feeding mechanism 66 including the guide member 71 and the guide member 72 and the like moves together with the cover 23 in the retracting direction (upstream side in the transport direction Y) to detect the medium. The device 80 is exposed. That is, since the medium detection device 80 is positioned so that the reading position is upstream of the second path merging portion J2 in the transport direction Y, when the guide member 71 forming the second merging portion 76 is retracted rearward, FIG. 7 and 8 are exposed. In particular, since the reading position is located upstream of the second merging portion 76 in the transport direction Y, when the guide member 71 forming the second merging portion 76 is retracted rearward, as shown in FIGS. The part 88 is also exposed. For example, cleaning for removing dirt on the surface of the window 88 can be performed while the medium detection device 80 is assembled to the main body 20.

Next, a detailed configuration of the medium detection device 80 will be described with reference to FIGS.
As shown in FIG. 8, the medium detection device 80 has a long shape extending in the width direction X slightly longer than the width of the maximum width medium P. Two window portions 88 are provided along the width direction X (the longitudinal direction of the casing). In the printing apparatus 11 according to the present embodiment, center feeding of the medium P is performed so that the width center of the medium P passes through the width center position of the feeding path regardless of the size. The two window portions 88 and the medium guide portion 81C form a medium support portion 81B. Further, the medium detection device 80 has a connector 81E at the bottom of the housing 81. A connector (not shown) connected to the wiring from the control unit 120 is connected to the connector 81E, and a detection signal of the sensor 83 is input to the control unit 120 via the connector 81E and a wiring (not shown).

  As shown in FIG. 9, the upper surface of the medium detection device 80 includes a medium guide part 81A, two window parts 88, a support part 81F interposed between the two window parts 88, a medium guide part 81C, and an extension part 81D. Prepare. The medium P fed from the cassette 21 is guided by the medium guiding portion 81A. Further, the medium P fed from the cassette 21 and the medium P fed from the feeding tray 22 are guided to a support surface including upper surfaces of the window portion 88, the support portion 81F, and the medium guide portion 81C. A plurality of extending portions 81 </ b> D extend in a comb-like shape, and each of the extending portions 81 </ b> D is inserted into a gap between a plurality of conveying roller pairs 46 provided in the width direction X. The medium P when being inserted into the transport roller pair 46 is supported by the upper surfaces of the plurality of extending portions 81D.

  As shown in FIG. 10, the casing 81 of the medium detection device 80 includes a base 100 and a cover 110. A pair of rail portions 84 and 85 are provided on the upper surface of the base 100 so as to extend in parallel to each other along the longitudinal direction. The carriage 82 is assembled so as to be movable in the longitudinal direction of the casing 81 along the pair of rail portions 84 and 85. In addition, a pair of pulleys 86 are assembled on the upper surface of the base 100 at positions corresponding to both ends in the longitudinal direction of the base 100 with a predetermined interval in the longitudinal direction. An endless belt 87 is wound around the pair of pulleys 86, and a carriage 82 is fixed to a part of the belt 87. The sensor 83 provided on the carriage 82 includes a pair of sensors 83A and 83B arranged at different positions in the longitudinal direction (width direction X) of the casing 81. The carriage 82 and the central portion in the longitudinal direction on the upper surface of the base 100 are connected via a flexible flat cable 89. In addition, a position sensor 90 that detects that the carriage 82 is at a home position (home position) located at the end of the movement path along the width direction X is provided at the longitudinal end of the upper surface of the base 100. Is provided. In the following description, the sensor 83A may be referred to as a first sensor 83A and the sensor 83B may be referred to as a second sensor 83B.

  As shown in FIG. 10, the base 100 is formed with a plurality of screw holes 101 at an appropriate interval in the circumferential direction on the peripheral edge thereof. Screws 111 inserted into a plurality of screw insertion holes (not shown) formed at positions corresponding to the screw holes 101 are screwed into the corresponding screw holes 101 on the base 100 side at the periphery of the cover 110. As a result, the base 100 and the cover 110 are assembled together to form the housing 81.

  As shown in FIG. 11, the carriage 82 has a home position HP indicated by a solid line in the drawing and an end opposite to the home position HP in the width direction X. The anti-home indicated by a two-dot chain line in the drawing. It can move between positions AP. One end portion of the flexible flat cable 89 is fixed to the central portion in the longitudinal direction of the peripheral portion of the base 100, and a portion extending from the fixed portion of the flexible flat cable 89 is wired along one rail portion 85 and in the middle. After being bent in an arc shape, wiring is performed along the other rail portion 84 and the other end portion is connected to the carriage 82. As the carriage 82 moves, the arc-shaped portion of the flexible flat cable 89 moves in the width direction X, so that the electrical connection with the moving carriage 82 is maintained.

  As shown in FIG. 11, the home position HP and the non-home position AP of the carriage 82 are end positions on both sides when the carriage 82 moves in the width direction X. The position sensor 90 is turned on when the carriage 82 is at the home position HP, and is turned off when the carriage 82 is at a position away from the home position HP.

  As shown in FIG. 12, an electric motor 103 is assembled on the back surface of the base 100. The drive shaft of the electric motor 103 is connected to one pulley 86 (the left pulley 86 in FIG. 11). The electric motor 103 of this example is a stepping motor. A connector 104 is connected to the tip of the wiring extending from the electric motor 103. A connector (not shown) connected to a wiring extending from the control unit 120 is connected to the connector 104, and electric power and a control signal are input from the control unit 120 to the electric motor 103 through the wiring. The electric motor 103 is driven forward / reversely based on a control signal (step control signal) from the control unit 120, so that the carriage 82 reciprocates in the width direction X by forward / reverse rotation of the belt 87.

  Further, as shown in FIG. 12, the wiring of the flexible flat cable 89 extends from the front surface side (inner surface side) to the back surface side of the base 100 and is exposed on the back surface of the base 100 and is held by a predetermined path. In a state, it is wired on the back surface and connected to the connector 81E. In addition, the wiring 105 extending from the position sensor 90 extends from the front surface side (inner surface side) to the back surface side of the connector 81E and is exposed, and the wiring 105 holds the back surface of the base 100 on a predetermined path. In this state, it is wired and connected to the connector 81E.

  As shown in FIG. 13, the two sensors 83 </ b> A and 83 </ b> B include a light emitting unit 106 and a light receiving unit 107. When the light receiving unit 107 receives the reflected light reflected by the light emitted from the light emitting unit 106, the sensors 83A and 83B output a detection signal having a voltage level corresponding to the amount of received light. The wiring 89A extending from the first sensor 83A is partly folded and folded in the middle, and is connected to the wiring 89B extending from the second sensor 83B to form one flexible flat cable 89. The flexible flat cable 89 is inserted through a wiring hole formed in the carriage 82 and extends to the back surface side of the carriage 82, and is then wired along the inner surface of the rail portion 84.

  As shown in FIG. 13, the position sensor 90 includes a light emitting unit 90A and a light receiving unit 90B. The carriage 82 includes a detected portion 82A that protrudes outward in the width direction X from the side portion on the home position HP side. When the carriage 82 is at the home position HP, the detected part 82A inserted in the recess 90C between the light emitting part 90A and the light receiving part 90B blocks light projection from the light emitting part 90A to the light receiving part 90B. The position sensor 90 is in a detection state. On the other hand, in a state where the carriage 82 has moved from the home position HP to the non-home position AP, the detected part 82A is retracted from the recess 90C, and the light receiving part 90B receives the light projection from the light emitting part 90A to the light receiving part 90B. As a result, the position sensor 90 is not detected.

  As shown in FIG. 14, the rail portion 84 includes a vertical portion 84A that extends vertically in the vertical direction Z with respect to the base 100, and a support portion 84B that is bent from the upper end portion of the vertical portion 84A and extends horizontally. Have. The carriage 82 is provided with a positioning mechanism 114 in which the pressing member 112 is pressed by the urging force of the compression spring 113 and pressed against the suspending portion 84 </ b> A of the rail portion 84. The carriage 82 is positioned in the transport direction Y by pressing the pressing member 112 in the horizontal direction with a predetermined urging force against the vertical portion 84A of the rail portion 84. For this reason, rattling in the conveyance direction Y of the carriage 82 is suppressed.

  As shown in FIG. 15, the carriage 82 has a positioning mechanism 118 in which the pressing member 116 is pressed against the support portion 84 </ b> B of the rail portion 84 by being pressed by the urging force of the compression spring 117. The carriage 82 is positioned in the vertical direction Z by pressing the pressing member 116 against the support portion 84B of the rail portion 84 with a predetermined urging force. For this reason, rattling of the carriage 82 in the vertical direction is suppressed. In addition, the carriage 82 is fixed to the belt 87 in a state where the belt 87 is gripped by a gripping portion 82 </ b> B protruding from the side portion on the upstream side in the transport direction Y of the carriage 82. Further, a plate-like guide portion 82 </ b> C extending from the carriage 82 to the downstream side in the transport direction Y is guided to the upper surface of the rail portion 85. The carriage 82 can move in the width direction X along the rail portions 84 and 85 by driving the belt 87 while maintaining the posture in the transport direction Y and the vertical direction Z via the two types of positioning mechanisms 114 and 118. It has become.

  The conveyance roller pair 46 shown in FIGS. 2 and 6 is a registration roller, and determines the conveyance start timing of the medium P to the downstream side thereof. A skew removal operation for removing or reducing skew (skew) of the medium P is performed by abutting the leading end portion of the medium P that has been fed against the conveying roller pair 46 that is stopped. At this time, when the medium P is abutted against the conveyance roller pair 46 by the skew removing operation, the medium P is stopped and the skew is removed by rotating in the plane by the skew angle. After this skew removal operation, the feeding speed for feeding the rear end side of the medium P by the feeding sections 41 and 42 is matched with the transport speed for feeding the leading end side of the medium P by the rotation of the transport roller pair 46. The medium P is carried onto the conveyance belt 61 of the belt conveyance mechanism 58 at a constant conveyance speed.

  As shown in FIG. 6, the reading position of the sensor 83 is set to a position upstream in the transport direction Y from the nip portion where the transport roller pair 46 nips (nips) the medium P. The medium detection device 80 detects the side edge in the width direction X of the medium P after the skew removal. The medium detection device 80 can detect the side edge of the stopped medium P after skew removal or the low-speed medium P for which conveyance after skew removal has started. For this reason, for example, when the medium detection device detects the side edge of the medium P at a position downstream of the conveyance roller pair 46 in the conveyance direction Y, the side edge of the medium P after skew removal can be detected. A relatively high-speed medium P that reaches a certain transport speed is a detection target. For this reason, for example, when detecting the side edges on both sides of the medium P, the one side edge and the other side edge are detected at positions that are significantly different in the transport direction Y of the medium P. In this case, if the skew of the medium P remains slightly, the detection accuracy of the width and side edges of the medium P slightly decreases. On the other hand, according to the present embodiment in which the reading position of the sensor 83 is set on the upstream side in the conveyance direction Y with respect to the nip portion of the conveyance roller pair 46 used for the skew removing operation, the reading position of the sensor 83 is set. The side end position and width of the medium P can be acquired with higher accuracy than in the case of setting the downstream side in the transport direction Y with respect to the nip portion of the transport roller pair 46. Note that the side edge detection processing of the medium P may be performed during the conveyance of the medium P in addition to the timing after the skew removal, and the side edge detection may be performed at a plurality of different locations in the conveyance direction Y of the single medium P. .

  Next, the electrical configuration of the printing apparatus 11 will be described with reference to FIG. As shown in FIG. 16, the printing apparatus 11 includes a control unit 120 that comprehensively controls the printing apparatus 11, a medium detection device 80, the operation panel 14, the conveyance unit 32 that conveys the medium P, and the medium that is being conveyed. A print head 34 for printing on P is provided. The transport unit 32 feeds the medium P stored in the cassette 21 and the first feeding motor 121 that serves as the power source of the first feeding unit 41 that feeds the medium P set on the feeding tray 22. And a second feed motor 122 that is a power source of the second feed unit 42. Further, the transport unit 32 includes a first transport motor 123 serving as a power source for the transport roller pair 46 and the discharge mechanism unit 38 that transport the fed medium P, and a belt motor 124 serving as a power source for the belt transport mechanism 58. The second transport motor 125 is a power source for the transport roller pair 55 and the reverse transport roller pair 57 for transporting the medium P on which one surface is printed. A plurality of motors 121 to 125 are electrically connected to the controller 120 via the same number of motor drive circuits 126 to 130 as the number of motors in the transport system. The control unit 120 controls each of the motors 121 to 125 via the motor drive circuits 126 to 130, thereby performing reversal and discharge during feeding, transporting, and duplex printing of the medium P. An electromagnetic clutch capable of switching the conveyance roller pair 55 between forward rotation and reverse rotation is provided, and the power source of the conveyance roller pair 55 and the reverse conveyance roller pair 57 is the first conveyance motor 123 common to the conveyance roller pair 46, and the second The structure which abolished the conveyance motor 125 may be sufficient.

  In addition, the print head 34 is electrically connected to the control unit 120. For example, the control unit 120 controls the print head 34 based on the print image data in the print job data PD received from the host device (not shown), thereby printing on the portion of the medium P being conveyed on the conveyance belt 61. Ink droplets are ejected from the nozzles of the head 34, and an image or the like based on the print image data is printed on the medium P. The control unit 120 is electrically connected to the operation unit 16 and the display unit 15 that constitute the operation panel 14. Based on the operation signal input from the operation unit 16, the control unit 120 instructs various setting information corresponding to the item selected from the menu displayed on the display unit 15, printing, scanning, and copying. Accept information. In addition, the control unit 120 causes the display unit 15 to display the above-described menu and a message for notifying the user when a failure or abnormality occurs.

  Further, the control unit 120 performs the skew removal operation of the medium P as follows. The control unit 120 drives the feeding motor 121 or 122 in a state where the driving of the first transport motor 123 is stopped, so that the leading end portion of the fed medium P abuts against the stopped transport roller pair 46. Thus, a skew removing operation for removing or reducing skew (skew) of the medium P is performed. Then, when the feeding motor 121 or 122 has been rotated by the set rotation amount necessary for the skew removal operation, the control unit 120 temporarily stops driving the feeding motor 121 or 122. After the skew removal operation, the feeding motor 121 or 122 and the first transport motor 123 are driven while synchronizing the rotation speed, so that the medium P is transported onto the transport belt 61 at a constant transport speed. The controller 120 starts driving the belt motor 124 before the medium P is transported to the transport belt 61, and the medium P is transported on the transport belt 61 driven at a constant transport speed. Carry in at speed.

  In addition, the control unit 120 illustrated in FIG. 16 is electrically connected to the electric motor 103 that serves as the power source of the carriage 82 of the medium detection device 80, the position sensor 90, and the first sensor 83A and the second sensor 83B on the carriage 82. Has been. The control unit 120 drives and controls the electric motor 103 via the motor drive circuit 131, thereby performing movement control for moving the carriage 82 forward and backward in the width direction X of the medium P and targeting the carriage 82. Position control to stop at the stop position.

  Further, the control unit 120 shown in FIG. 16 determines whether or not the carriage 82 is at the home position HP based on the detection signal SH (see FIGS. 18 and 19) input from the position sensor 90. If the detection signal SH input from the position sensor 90 is at a signal level (for example, H level) indicating that the carriage 82 is at the home position HP, the control unit 120 recognizes that the carriage 82 is at the home position HP, and If the signal level indicating that 82 is not at the home position HP (for example, L level), it is determined that the carriage 82 is not at the home position HP.

  Further, the control unit 120 shown in FIG. 16 receives the detection signal SA from the first sensor 83A and the detection signal SB (both see FIGS. 18 and 19) from the second sensor 83B while the carriage 82 is moving. To do. The control unit 120 detects the side edges on both sides in the width direction X of the medium P to be detected based on the detection signals SA and SB input from the first sensor 83A and the second sensor 83B. For example, from the detection result of the side edge in the width direction X of the medium P, the control unit 120 determines the side end positions PE1 and PE2 (see FIG. 17), the print range in the width direction X when the print head 34 performs printing, Media information relating to the width (for example, paper width) and the width such as the medium size (for example, paper size) defined from the width is acquired.

  The control unit 120 illustrated in FIG. 16 includes, for example, a computer and a memory (not shown), and includes a plurality of functional units necessary for medium detection processing that function when the computer executes a program stored in the memory. The control unit 120 includes, as a plurality of functional units, a width information acquisition unit 141 that acquires width information of the medium P, a carriage control unit 142 that drives and controls the electric motor 103, and a failure detection unit that can detect failures in the sensors 83A and 83B. 143 and a detection processing unit 144 capable of detecting the side end positions PE1 and PE2 of the medium P based on the detection signals SA and SB of the sensors 83A and 83B. The width information acquisition unit 141 acquires the width information of the medium P from the print setting information included in the print job data PD received by the control unit 120. The width information is, for example, medium size information. For example, reference data indicating the correspondence between the medium paper size and the width information is stored in the memory, and the width information acquisition unit 141 acquires the width information by referring to the reference data based on the obtained medium size.

  The carriage control unit 142 shown in FIG. 16 controls the electric motor 103 via the motor drive circuit 131, thereby performing control for moving the carriage 82 in the width direction X and position control for stopping the carriage 82 at the target position. The failure detection unit 143 determines whether or not the detection signals SA and SB from the first sensor 83A and the second sensor 83B have values at the time of failure when the medium P is not being conveyed. If there is a sensor that takes a value, that sensor is detected as a failure. In this example, if any of the sensors 83A and 83B has a sensor that takes the H level, which is a detection value when the medium P is present, even though the medium P is not present, the sensor is detected as a failure. Further, if the sensors 83A and 83B receive the reflected light from the light reflecting surface 71C and take the L level that is the detection value when there is no medium P, the sensors 83A and 83B are assumed to be normal.

  The detection processing unit 144 detects the side edge in the width direction X of the medium P based on the detection signals SA and SB of the first sensor 83A and the second sensor 83B. The detection processing unit 144 includes a counter 145 that counts the position in the width direction X of the carriage 82 with the home position HP as an origin, and a medium detected by the other when one of the first and second sensors 83A and 83B fails. And a calculation unit 146 that calculates the other side end position of the medium P based on one side end position of P and the width information.

  FIG. 17 is a schematic diagram for explaining a method of detecting the side edge of the medium by two sensors, and is a view seen from the back side of the medium. As shown in FIG. 17, the first sensor 83 </ b> A and the second sensor 83 </ b> B are attached to the upper part of the carriage 82 in a state where the center distance L <b> 1 is separated in the width direction X. When the carriage 82 is positioned at the home position HP (solid line position in FIG. 17), in the case of a small-sized medium SP having a small width dimension, both sensors 83A and 83B are both positioned outside the medium SP in the width direction. Not detected. On the other hand, in the case of a large-sized medium LP having a large width dimension, when the carriage 82 is positioned at the home position HP, one sensor on the home position HP side (second sensor 83B in the example of FIG. 17) is in the width direction of the medium LP. It is located outside X and the medium LP is not detected. On the other hand, the other sensor on the side opposite to the home position AP (first sensor 83A in the example of FIG. 17) is located at a position facing the medium LP and detects the medium LP.

  In this example, when the medium P having the maximum width is the detection target, when the carriage 82 is at the left end position E1 (for example, the home position HP) in the movable range, the right sensor 83A of the two sensors 83A and 83B. Detects the maximum width medium P, and the left sensor 83B does not detect the maximum width medium P. On the other hand, when the carriage 82 is at the right end position E2 in the movable range, the left sensor 83B of the two sensors 83A and 83B detects the maximum width medium P, and the right sensor 83A detects the maximum width medium P. Is not detected. Thus, the movable range of the carriage 82 is relatively narrow relative to the width of the maximum width medium P. For this reason, the size dimension in the width direction X of the medium detection device 80 is kept relatively short relative to the width of the maximum width medium P, and the longitudinal direction of the medium detection device 80 coincides with the width direction X. Even if it is provided in the apparatus main body 20 in the orientation, the size dimension in the width direction X of the printing apparatus 11 is relatively short.

  The control unit 120 shown in FIG. 16 determines the number of sensors used in the side edge detection process for detecting the side edge positions PE1 and PE2 on both sides of the medium P, out of the two sensors 83A and 83B. Switch according to (dimension). That is, when the medium width based on the width information is a small-sized medium SP that is equal to or smaller than the set width, the control unit 120 uses only one sensor (for example, the first sensor 83A) and uses the side end position PE1 of the medium SP. , PE2 is detected. In addition, when the medium width is a large-sized medium LP in which the medium width exceeds the set width, the control unit 120 detects the side end positions PE1 and PE2 of the medium LP using both the first and second sensors 83A and 83B. . Here, as shown in FIG. 17, the set width is a medium width in which the two sensors 83A and 83B cannot detect the medium P (for example, medium SP) when the carriage 82 is at the home position HP indicated by the solid line. It is set to a value that is equal to or larger than the maximum medium width and less than the minimum medium width among the medium widths that the first sensor 83A can detect the medium P (for example, medium LP). In FIG. 17, when the width direction X in which the carriage 82 can move is the left-right direction, the first sensor 83A corresponds to an example of the right sensor, and the second sensor 83B corresponds to an example of the left sensor. Further, the first side end PE1 of the medium P corresponds to an example of the left end, and the second side end PE2 corresponds to an example of the right end.

  18 and 19 show detection signals output from the sensors 83A, 83B, and 90 when the side edges on both sides in the width direction X of the medium P are detected. FIG. 18 is a signal waveform of each detection signal when detecting the side edge of the small-sized medium SP whose medium width is equal to or smaller than the set width, and FIG. 19 is the side of the large-sized medium LP whose medium width exceeds the set width. It is a signal waveform of each detection signal when an end is detected. In both figures, the horizontal direction indicates time t, and the vertical direction indicates the voltage level of each detection signal SA, SB, SH. Since the carriage 82 moves at a constant speed V1, the time t in the horizontal direction in both figures corresponds to the number of steps of the electric motor 103, that is, the moving distance of the carriage 82.

  As shown in FIG. 18, when the carriage 82 is located at the home position HP (solid line position in FIG. 17) and the detection signal SH is at the H level, if the detection target is a small-sized medium SP, both sensors 83A, 83B does not detect the medium SP, and the detection signals SA and SB are both at the L level. When the carriage 82 starts moving from the home position HP, first, the first sensor 83A on the right side detects the first side end PE1 on the left side, and the detection signal SA rises from L level to H level. When the carriage 82 further moves for a time t1 (= L1 / V1) corresponding to the center distance L1 between the two sensors 83A and 83B, the left second sensor 83B detects the right second side end PE2 and detects the detection signal. SB rises from L level to H level. Next, when the first sensor 83A moves from the time point of detection of the first side end PE1 for a time t2 corresponding to the medium width, the first sensor 83A detects the second side end PE2, and the detection signal SA changes from H level to L level. To fall. Note that the number of steps of the electric motor 103 output during the period of time t2 corresponds to the moving distance of the carriage 82 during that period, which corresponds to the width of the medium SP.

  Further, as shown in FIG. 19, when the carriage 82 is positioned at the home position HP (solid line position in FIG. 17) and the detection signal SH is at the H level, if the detection target is a large-sized medium LP, The first sensor 83A detects the medium LP and is at the H level, and the second sensor 83B on the left side does not detect the medium LP and is at the L level. When the carriage 82 starts to move from the home position, the left second sensor 83B first detects the left first side end PE1, and the detection signal SB rises from the L level to the H level. When the carriage 82 further moves for a time t3 corresponding to the medium width, the first sensor 83A on the right side detects the second side end PE2 on the right side, and the detection signal SA falls from the H level to the L level. Note that the number of steps of the electric motor 103 output during the period of time t3 corresponds to the moving distance of the carriage 82 during that period, which corresponds to the width of the medium LP.

  Next, the operation of the printing apparatus 11 will be described with reference to FIGS. When the power of the printing apparatus 11 is turned on, the control unit 120 executes the medium side edge detection process shown in FIG. Further, in the medium side edge detection process shown in FIG. 20, when the controller 120 detects a failure of one of the sensors 83A and 83B, the control unit 120 executes the medium side edge detection process at the time of failure shown in FIG.

  First, in step S11, sensor failure detection processing is performed. This sensor failure detection process is performed when the transport unit 32 is not transporting the medium P. Here, the time when the medium P is not being conveyed includes when the printing apparatus 11 is turned on, in a print standby state waiting for reception of a print job, when returning from the sleep mode (sleep mode), and the like. It is done. In this example, since the light reflection surface 71C is provided in a region facing the movement path of the sensors 83A and 83B, the sensors 83A and 83B can be located at any position on the movement path with the light reflection surface 71C. opposite. For example, in a state where the carriage 82 is at the home position HP, the sensors 83A and 83B emit light and receive the reflected light reflected by the light reflecting surface 71C. If the light received from the sensors 83A and 83B received the reflected light reflected by the light reflecting surface 71C does not exceed the threshold and the detection signal is at the H level when the medium is present, Is determined. This failure detection process is performed for each of the two sensors 83A and 83B. When the light reflecting surface 71C exists only in a region facing a part of the movement path of the sensors 83A and 83B, and the two sensors 83A and 83B are not located at a position facing the light reflecting surface 71C, the control unit 120 Is driven and controlled by the electric motor 103, and the two sensors 83A and 83 are arranged at positions facing the light reflecting surface 71C. And the control part 120 performs a failure detection process based on each detection signal by making it light-emit in the state which has arrange | positioned the two sensors 83A and 83B in the position facing 71 C of light reflection surfaces.

  In step S12, it is determined whether or not the sensor is malfunctioning. In this failure determination, if any one of the two sensors 83A and 83B is failed, it is determined as a failure. If there is even one failure, the process proceeds to step S13, and if not, the process proceeds to step S14.

  In step S13, failure notification is performed. That is, the control unit 120 notifies the user of the failure, for example, by displaying a message indicating the failure on the display unit 15. Note that the failure notification may be a notification by light emission or blinking of a light emitting unit such as a light emitting diode, a notification by a buzzer or sound, or a combination of these notification methods.

  In step S14, it is determined whether a print job including width information has been received. In the printing apparatus 11 of this example, the print job includes print setting information, and one of the print setting information includes medium width information (for example, paper size). That is, the process of step S14 is synonymous with determining whether a print job has been accepted. When receiving a print instruction by a method other than a print job, for example, when connecting a memory card (not shown) to the printing apparatus 11 and operating the operation unit 16 to print a selected image from the memory card, the control unit 120 Acquires width information (for example, paper size) of the medium P selected by the operation unit 16.

  In step S15, it is determined whether or not all the sensors are normal. Specifically, the failure detection unit 143 of the control unit 120 performs failure detection processing for detecting failures in the first and second sensors 83A and 83B, and whether the sensors 83A and 83B are all normal based on the failure detection processing results. Determine whether or not. As the failure detection processing, detection signals SA and SB from the sensors 83A and 83B that should have received the reflected light reflected by the light reflecting surface 71C in a state where there is no medium before the medium P is fed. If the value is not a value when there is no medium (for example, L level) but a value when the medium is detected (for example, H level), the sensor is determined to be faulty. If all the sensors 83A and 83B are normal, the process proceeds to step S16, and if one of the sensors 83A and 83B has a failure, the process proceeds to step S19.

  In step S16, it is determined whether the width of the medium is equal to or smaller than the set width. Then, if the width of the medium P acquired from the width information is equal to or smaller than the set width, that is, if the medium P is a small-sized medium SP, the control unit 120 proceeds to step S17. On the other hand, if the width of the medium P acquired from the width information exceeds the set width, that is, if the medium P is a large-sized medium LP, the process proceeds to step S18.

  In step S17, a first side edge detection process for detecting both side edges of the medium using one sensor is performed. The carriage control unit 142 of the control unit 120 drives and controls the electric motor 103 via the motor drive circuit 131 and moves the carriage 82 in the width direction X. In this example in which the electric motor 103 is a stepping motor, the carriage control unit 142 controls the electric motor 103 by instructing the number of steps. The counter 145 is reset when the carriage 82 is at the home position HP and the position sensor 90 detects the detected portion 82A, and count processing for adding or subtracting the number of steps used for control according to the traveling direction of the carriage 82. I do. As a result, the counter 145 stores a count value corresponding to the position of the carriage 82 in the width direction X. When the medium P is a small medium SP such as A4 size whose width is equal to or smaller than the set width based on the width information, the carriage controller 142 moves the carriage 82 from the home position HP to a position A1 indicated by a two-dot chain line in FIG. To move. During the movement process of the carriage 82, the detection processing unit 144 detects the side end positions PE1 and PE2 on both sides of the small-sized medium SP using only the first sensor 83A.

  At this time, as shown in FIG. 18, the control unit 120 inputs the detection signal SH of the position sensor 90, the detection signal SA of the first sensor 83A, and the detection signal SB of the second sensor 83B. The detection processing unit 144 of the control unit 120 monitors the detection signal SA of the first sensor 83A, and when the detection signal SA rises from the L level to the H level, acquires the count value of the counter 145 at that time, and the count value And the known first distance (for example, L1 / 2) in the width direction X from the carriage width center position to the first sensor 83A, the first side end position PE1 is calculated. The calculated first side end position PE1 is stored in the memory. Then, when the detection signal SA of the first sensor 83A falls from the H level to the L level during the movement of the carriage 82, the count value of the counter 145 at that time is acquired, and the count value and the above-described known first value are obtained. The second side end position PE2 is calculated using the distance, and the calculated second side end position PE2 is stored in the memory. Thus, if the two sensors 83A and 83B do not detect the medium SP when the carriage 82 is at the home position HP, only the first sensor 83A positioned on the front side in the traveling direction of the movement process when the carriage 82 detects the medium is used. By using it, the side end positions PE1 and PE2 on both sides of the medium P can be detected with a relatively short movement distance of the carriage 82.

  In step S18 in FIG. 20, a second side edge detection process for detecting both side edges of the medium using two sensors is performed. The carriage control unit 142 of the control unit 120 instructs the number of steps to drive and control the electric motor 103 via the motor drive circuit 131 to move the carriage 82 in the width direction X. At this time, the counter 145 counts the position in the width direction X of the carriage 82 with the origin when the carriage 82 is at the home position HP. The carriage control unit 142 moves the carriage 82 from the home position HP in the width direction X, for example, two points in FIG. 17 when the width of the medium P exceeds the set width based on the width information. Move to position A2 indicated by the chain line. During the movement process of the carriage 82, the detection processing unit 144 detects the side end positions PE1 and PE2 on both sides in the width direction X of the large-sized medium LP using both the first and second sensors 83A and 83B. .

  Specifically, as shown in FIG. 19, when the carriage 82 is at the home position HP and the detection signal SH is at the H level, the first sensor 83A is in the state of detecting the medium LP, and the detection signal SA is at the H level. It is in. On the other hand, the detection signal SB of the second sensor 83B that has not detected the medium LP is at the L level. When the carriage 82 starts moving from the home position HP, the detection processing unit 144 first monitors the detection signal SB of the second sensor 83B. When the detection signal SB of the second sensor 83B rises from the L level to the H level, the detection processing unit 144 acquires the count value of the counter 145 at that time, and from the count value and the carriage width center position to the second sensor 83B. The first side end position PE1 is calculated using the known second distance in the width direction X (for example, L1 / 2). The calculated first side end position PE1 is stored in the memory. Then, when the detection signal SA of the first sensor 83A falls from the H level to the L level during the subsequent movement of the carriage 82, the count value of the counter 145 at that time is acquired, and the count value and the above-mentioned known first count are obtained. The second side end position PE2 is calculated using 1 distance, and the calculated second side end position PE2 is stored in the memory. In this way, if one of the two sensors 83A and 83B does not detect the medium LP when the carriage 82 is at the home position HP, the second sensor is located on the rear side in the traveling direction of the movement process when the medium is detected by the carriage 82. The first side end position PE1 is detected at 83B, and the second side end position PE2 is detected by the first sensor 83A located on the front side in the traveling direction. Therefore, the side end positions PE1 and PE2 on both sides of the medium P can be detected with a relatively short movement distance of the carriage 82.

  In step S19 in FIG. 20, medium side edge detection processing at the time of failure is performed. The medium side edge detection process at the time of failure is performed by the computer of the control unit 120 executing a medium side edge detection process routine at the time of failure shown in FIG.

Hereinafter, the medium side edge detection process at the time of failure performed by the control unit 120 will be described with reference to FIG.
First, in step S21, it is determined whether or not it is a failure of only one sensor. That is, the control unit 120 determines whether the failure is caused by only one sensor using the detection result of the sensor failure detection process in step S11 of FIG. If only one sensor fails, the process proceeds to step S22. If only one of the sensors is not faulty, that is, if both of the two sensors are faulty, the process proceeds to step S26.

  In step S22, it is determined whether the width of the medium is equal to or smaller than the set width. This determination processing is the same as the determination processing in step S16 in FIG. 20, and is performed based on the width information. If the width of the medium P is equal to or smaller than the set width, the process proceeds to step S23. On the other hand, if the width of the medium P is not less than or equal to the set width, that is, if the width of the medium P exceeds the set width, the process proceeds to step S24.

  In step S23, a third side edge detection process for detecting both side edges of the medium using the other normal sensor is performed. For example, when the first sensor 83A is normal and the second sensor 83B is faulty, the first end similar to step S17 in FIG. 19 is detected using the normal first sensor 83A to detect the side edge positions PE1 and PE2 of the medium P. The side edge detection process is performed as a third side edge detection process. On the other hand, when the first sensor 83A is out of order and the second sensor 83B is normal, third side edge detection processing is performed to detect both side edge positions PE1 and PE2 of the medium P using the normal second sensor 83B. In the latter case, the count value of the counter 145 when the detection signal SB from the second sensor 83B rises from the L level to the H level is acquired, and the first value is used by using the count value and the known second distance. The side end position PE1 is calculated, and the calculated first side end position PE1 is stored in the memory. Further, the count value of the counter 145 when the detection signal SB falls from the H level to the L level is acquired, and the second side end position PE2 is calculated using the count value and the above-described known second distance. The calculated second side end position PE2 is stored in the memory.

  In step S24, it is determined whether or not the fourth side end detection process with estimation may be performed. In this example, the control unit 120 displays an inquiry message on the display unit 15 as to whether or not the fourth side edge detection process with estimation may be performed, and an operation in which the user operates the operation unit 16 as a response to the inquiry. Whether or not the fourth side end detection process can be executed is determined based on the signal. Alternatively, the registered information registered in advance by the user by operating the operation unit 16 of the printing apparatus 11 is read from the memory, and it is determined whether or not the fourth side edge detection process can be executed based on the registered information. If the execution of the fourth side end detection process is permitted, the control unit 120 proceeds to step S25, and if the execution of the fourth side end detection process is not permitted, the control unit 120 proceeds to step S27.

  In step S25, a fourth side end detection process is performed in which one side end is detected using the other normal sensor, and the other side end is estimated using the detection result of one side end and the width information. As shown in FIG. 17, in the printing apparatus 11 of this example, the movable range in which the carriage 82 can be moved from the end position E1 on the home position HP side to the end position E2 on the non-home position AP side is relatively short. . For this reason, the size dimension of the medium detection apparatus 80 in the width direction X, and hence the size dimension of the printing apparatus 11 in the width direction X, is shortened, which contributes to making the printing apparatus 11 compact. However, since the movable range of the carriage 82 is relatively short, when the large-sized medium LP is a detection target, the side edges on both sides of the medium LP cannot be detected only with the other normal sensor. For this reason, one side edge position is detected by a normal sensor, and the other side edge position that cannot be detected due to a failure of the other sensor is estimated by calculation using the side edge position and width information detected by the normal sensor. To do. Specifically, the control unit 120 detects one side end by the other sensor that is not out of the first and second sensors 83A and 83B. For example, when the first sensor 83A is normal and the second sensor 83B is out of order, one side end position PE2 is detected by the first sensor 83A. Further, when the first sensor 83A is out of order and the second sensor 83B is normal, the one side end position PE1 is detected by the second sensor 83B. The calculation unit 146 of the detection processing unit 144 calculates the other side end position using the detected one side end position and the width information of the medium P. Assuming that one side edge position detected by the other sensor is x1 and the medium width is W1, the other side edge position x2 of the medium P is x2 = x1−W1 and second when the first sensor 83A is normal. Calculated by x1 + W1 when the sensor 83B is normal. Thus, the side end positions PE1 and PE2 on both sides of the medium P are acquired by the fourth side end detection process.

  The control unit 120 controls the printing range in the width direction X of the print head 34 based on the side edge positions PE1 and PE2 on both sides of the medium P acquired by the medium side edge detection process. As a result, printing is performed in an appropriate position range in the width direction X of the medium P. The control unit 120 acquires the width of the medium P from the side end positions PE1 and PE2, and if the width differs from the medium width acquired from the width information beyond the allowable range, a message indicating a medium size error. Is displayed on the display unit 15.

  In step S26, it is determined whether printing can be performed without detecting the side edge. In this example, for example, the control unit 120 displays an inquiry message on the display unit 15 and inquires of the user whether printing can be performed without detecting the side edge of the medium P. When the control unit 120 receives a response indicating that printing is to be performed without detecting the side edge based on the operation signal from the operation unit 16 (Yes in S26), the control unit 120 proceeds to step S27, while printing without detecting the side edge. If a response to the effect of not implementing is received (No in S26), the routine is terminated. In the latter case, printing itself is stopped.

  In step S27, the side edge detection process is stopped. The control unit 120 includes a flag for managing whether or not the side edge detection process can be executed, and writes a value indicating cancellation to the flag. In this case, the control unit 120 performs printing based on the print job data PD without performing side edge detection processing. At this time, the control unit 120 controls the print range of the print head 34 based on the medium width acquired from the width information.

  In addition, in FIG. 20, it is good also as a structure which abolishes the process of step S24 and step S25, and does not perform the 4th side edge detection process accompanied by estimation. Moreover, when a negative determination is made in step S24, the process may proceed to a determination process in step S26. Further, the processing in step S26 may be abolished, and printing may be stopped when all the sensors 83A and 83B are out of order.

According to the first embodiment described in detail above, the following effects can be obtained.
(1) The medium detection device 80 that detects the side edge in the width direction X that intersects the transport direction Y of the medium P is disposed upstream of the print head 34 in the transport direction Y of the medium P. The medium detection device 80 is provided at a position that is upstream of the print head 34 in the transport direction Y and is movable in the width direction X independently of the print head 34, and at a different position in the width direction X of the carriage 82. The two sensors 83A and 83B and an electric motor 103 as an example of a power source for moving the carriage 82 are provided. The control unit 120 controls the electric motor 103 to move the carriage 82 to cause the sensors 83A and 83B to detect the side end in the width direction X of the medium P. Since the two sensors 83A and 83B are arranged at different positions in the width direction X on the carriage 82, the carriage for detecting the side edge in the width direction X of the medium P by using the two sensors 83A and 83B properly. The amount of movement of 82 can be reduced. Therefore, the side edges on both sides in the width direction X of the medium P can be detected without depending on the printing method (for example, the line printing method or the serial printing method) as to whether or not the print head 34 moves. However, the size in the width direction of the printing apparatus 11 can be kept relatively short.

  (2) Since the carriage 82 is provided so as to be movable in the width direction X at a position opposite to the print head 34 side with respect to the transport path 30 of the medium P transported by the transport unit 32, from the optical sensor. The two sensors 83 </ b> A and 83 </ b> B irradiate light toward the medium P from a position opposite to the print head 34 with the conveyance path 30 interposed therebetween. Therefore, compared to the case where the two sensors 83A and 83B are arranged on the same side as the print head 34 with respect to the medium P, ink mist from the print head 34 is less likely to adhere. Therefore, it is easy to avoid a decrease in detection accuracy of the sensors 83A and 83B due to ink stains.

  (3) The casing 81 of the medium detection device 80 has a medium support portion 81B that supports the medium P that is transported through the transport path 30, and transmits light from the two sensors 83A and 83B to the medium support portion 81B. A possible window 88 is provided. Therefore, since the sensors 83A and 83B are protected by the window portion 88, they are not directly soiled by dust such as paper dust from the medium P or ink mist from the print head 34, so that the detection accuracy of the sensors 83A and 83B is improved. Can be kept relatively high. Further, the window 88 also serves as a part of the medium support portion 81B, and the distance between the medium P that slides on the upper surface of the window 88 and the sensors 83A and 83B can be made relatively short. High detection accuracy can be maintained.

  (4) Two window portions 88 are arranged along the width direction X in the medium support portion 81B. Therefore, the strength of the medium support portion 81B can be ensured to be relatively high and the cost of parts of the window portion 88 can be kept relatively low compared to the configuration in which one long window portion is provided over the moving area of the sensors 83A and 83B. be able to.

  (5) The plurality of window portions 88 are arranged at positions where the side edges on both sides in the width direction X of the medium P from the minimum width to the maximum width can be detected through the different window portions 88 by the two sensors 83A and 83B. . For example, the side edges on both sides of the medium P from the minimum width to the maximum width can be detected continuously. For example, even when an irregular medium P other than the regular medium P is conveyed, the side edge of the irregular medium P can be detected.

  (6) Since the electric motor 103, which is an example of the power source of the medium detection device 80, is a stepping motor, an encoder for acquiring the position of the carriage 82, which is necessary when a DC motor is used. Is no longer necessary. Therefore, the number of parts of the medium detection device 80 can be reduced as compared with the case where a DC motor is used. For example, it is easy to reduce the size of the medium detection device 80.

  (7) When the medium P has the maximum width, when the carriage 82 is at the left end position E1 in the movable range, the right sensor 83A of the two sensors 83A and 83B detects the medium P having the maximum width, The left sensor 83B does not detect the medium P having the maximum width. On the other hand, when the carriage 82 is at the right end position E2 in the movable range, the left sensor 83B of the two sensors 83A and 83B detects the maximum width medium P, and the right sensor 83A detects the maximum width medium P. Is not detected. That is, when the medium P has the maximum width, when the carriage 82 is at the left end position E1, only the left sensor 83B is disengaged from the medium P in the width direction, and when the carriage 82 is at the right end position, Only the sensor 83A is detached from the medium P in the width direction X. For this reason, since the movable range of the carriage 82 is relatively narrow relative to the width of the medium P having the maximum width, the size dimension in the width direction X of the printing apparatus 11 provided with the medium detection device 80 can be kept relatively short. When the medium P has the maximum width, the left side edge PE1 of the medium P is detected by the left sensor 83B, and the right side edge PE2 of the medium P is detected by the right sensor 83A. Side edges PE1 on both sides of the medium P1. PE2 can be detected.

  (8) The left end (first side end PE1) of the medium P is detected by the left second sensor 83B, and the right end (second side end PE2) of the medium P is detected by the right first sensor 83A. Therefore, the movement distance required for the carriage 82 when detecting the side edges on both sides in the width direction X of the medium P can be made relatively short. Therefore, the size dimension in the width direction X of the medium detection device 80 can be shortened. For example, an increase in the width direction size of the printing apparatus 11 due to the provision of the medium detection device 80 can be avoided, and the time required to acquire medium information regarding the width direction X of the medium P can be kept relatively short. it can.

  (9) When the width of the medium P based on the width information acquired by the width information acquisition unit 141 is longer than the set width, the control unit 120 controls the electric motor 103 and the left end (first side end PE1) of the medium P. Is detected by the second sensor 83B on the left side, and the right end (second side end PE2) of the medium P is detected by the first sensor 83A on the right side. Therefore, it is possible to make the movement distance relatively short for the carriage 82 required when detecting the side edges PE1 and PE2 on both sides of the medium P. Thereby, the size in the width direction of the medium detection device 80 can be made relatively short, and the time required for obtaining the medium information can be made relatively short.

  (10) A guide member 71, which is an example of a medium guide member, is positioned at a position where the sensors 83A and 83B made of light-reflective sensors face the window 88 that transmits light at the time of detection with the conveyance path 30 interposed therebetween. A portion of the guide member 71 that faces the movement path of the sensors 83A and 83B is a light reflecting surface. Therefore, it is not necessary to separately provide a member dedicated to the light reflecting surface, so that the medium guiding structure of the transport unit 32 on the upstream side in the transport direction Y from the print head 34 can be configured relatively compactly.

  (11) Since the guide member 71 is made of metal, the light reflecting surface 71C can be formed relatively easily by polishing, for example, a portion of the guide member 71 that faces the movement path of the sensors 83A and 83B.

  (12) When the transport unit 32 is not transporting the medium P, the control unit 120 monitors the detection signals SA and SB of the sensors 83A and 83B and receives the reflected light from the light reflecting surface 71C. If the reflected light from the light reflecting surface 71C is not received, the sensor is regarded as a failure. Therefore, it is possible to avoid as much as possible inconvenience that wrong medium information is acquired, such as erroneous detection of the side edge position based on the detection signal of the failed sensor.

  (13) When one of the two sensors 83A and 83B is out of order, the control unit 120 detects both side edges PE1 and PE2 of the medium P with the other sensor. Therefore, even if one of the sensors breaks down, the necessary medium information can be acquired by detecting both ends PE1 and PE2 of the medium P. In particular, when the medium P is a large size, even when a relatively short movable range of the carriage 82 in which the side edges PE1 and PE2 cannot be detected by only one sensor is set, the small size having a width equal to or smaller than the set width. With respect to the medium SP, it is possible to acquire the necessary medium information by detecting both ends PE1 and PE2 of the medium SP with the other sensor that is not malfunctioning.

  (14) When one of the two sensors 83A and 83B is out of order and the width of the medium P is larger than the set width, the control unit 120 uses one of the two side edges PE1 and PE2 of the medium P with the other sensor. Is detected, and the calculation unit 146 estimates the position of the other side end by calculation based on the detection result of the one side end and the width information. Therefore, when one of the sensors breaks down, medium information including both side edge positions PE1 and PE2 of the medium LP can be acquired even for a medium LP having such a large width that the other edge cannot be detected by the other sensor.

  (15) The printing apparatus 11 includes a conveyance path 30 that conveys the medium P from the cassette 21 and the feeding tray 22 as an example of the medium placement unit along a path that can be printed by the print head 34, and a conveyance path 30. And a third feeding path 93 (an example of a double-sided printing path) that reverses the medium P on which one side is printed by the print head 34 and returns it to a position in the middle of the transport path 30. Then, the medium detection device 80 that can read the medium P in the width direction X and detect both side edges PE1 and PE2 of the medium P is positioned at a position upstream of the print head 34 in the transport direction Y of the medium P. Are arranged so as to be located on the upstream side in the transport direction Y with respect to the second path junction portion J2 (an example of the junction portion) where the transport route 30 and the third feeding route 93 merge. Therefore, although the medium detection device 80 is provided, the size of the printing device 11 in the transport direction Y can be made relatively short. For example, if it is attempted to adopt a configuration in which the medium detection device also reads the medium P on which one surface is re-feeded through the reverse feeding path 56, the joining portion is more transported than the reading position of the medium detection device. It is necessary to shift the position to the upstream side of Y. Accordingly, it is necessary to shift a portion of the transport path 30 and the reverse feed path 56 that is located on the upstream side in the transport direction with respect to the junction 76 to the upstream side in the transport direction Y. In this case, the size of the printing apparatus 11 in the transport direction Y is relatively long. On the other hand, the medium P on which one side is printed is not read, and the joining portion 76 is arranged on the downstream side in the transport direction Y from the reading position, so that the transport path 30 and the reverse feeding path 56 Of these, the portion located on the upstream side (rear side) in the transport direction Y with respect to the junction 76 can be disposed as close to the downstream as possible. As a result, both side edges PE1 and PE2 in the width direction X of the medium P can be detected without depending on whether the print head 34 is a movable type or a fixed type, and the size in the transport direction Y of the printing apparatus 11 can be determined. It can be kept relatively short.

  (16) In the medium detection device 80, the movement range in which the sensors 83A and 83B can detect both side ends in the width direction X of the medium P having the maximum width is long in the width direction X in which the carriage 82 can move using the electric motor 103 as a power source. Has a shape. That is, even if the medium detection device 80 that is slightly longer than the width of the medium P having the maximum width is provided in the printing device 11, the space for disposing the medium detection device 80 is the first. By designing the two-path merging portion J2 to be located downstream of the reading position in the transport direction Y, the size dimension of the printing apparatus 11 in the transport direction Y can be kept relatively short.

  (17) The medium detection device 80 can detect the side edges PE1 and PE2 of the medium P fed from both the cassette 21 and the feeding tray 22 by the printing device 11, and the size of the printing device 11 in the transport direction Y can be reduced. The medium detection device 80 can be provided while aiming.

  (18) The reading position of the medium detection device 80 is downstream of the first joining portion 75 where the two feeding paths 45 and 48 for feeding the medium P from the cassette 21 and the feeding tray 22 join in the transport direction Y. And on the upstream side of the second path junction portion J2. Therefore, the medium P fed from either the cassette 21 or the feeding tray 22 can be read at the reading position of the medium detecting device 80 to detect both side edges PE1 and PE2. For this reason, the medium P fed from either the cassette 21 or the feeding tray 22 can be printed at an appropriate position in the width direction X.

  (19) In particular, the reading position is located downstream of the first path merging portion J1 and upstream of the second path merging portion J2 in the transport direction Y. With this configuration, the distance between the sensors 83A and 83B and the medium P can be kept substantially constant, so that higher side edge detection accuracy can be ensured. Further, the reading position is located downstream of the first path joining portion J1 and upstream of the second joining portion 76 in the transport direction Y. With this configuration, the detection areas of the sensors 83A and 83B are protected by the guide member 71 with respect to the medium P on which one surface is re-feeded through the reverse feeding path 56. A decrease in side edge detection accuracy due to ink smear can be suppressed. For example, since printing ink applied to one surface of the re-paid medium P does not easily adhere to the window portion 88, the side edges of the medium P can be used even when the sensors 83A and 83B read the medium P through the window portion 88. High detection accuracy can be maintained.

  (20) The printing apparatus 11 includes a first feeding unit 41 as an example of a feeding mechanism capable of feeding the medium P placed on the feeding tray 22 and a second merging unit 76. A cover 23 assembled with a guide member 71 having some medium guide surfaces 71 </ b> A and 71 </ b> B is provided so as to be openable and closable with respect to the apparatus main body 20. Therefore, when the cover 23 is opened, the first feeding unit 41 and the guide member 71 are detached from the apparatus main body 20 together with the cover 23, and a part of the medium detection device 80 is exposed. As a result, the medium detection device 80 can be easily maintained and the medium detection device 80 can be removed relatively easily when it is necessary to remove it for maintenance or replacement.

In addition, the said embodiment can also be changed into the following forms.
The first side end and the second side end may be detected by different sensors even when the medium based on the width information is a small-sized medium having a width equal to or smaller than the set width. Even in the case of a large-sized medium whose width based on the width information is longer than the set width, the movement distance of the carriage is slightly increased, and the first side end and the second side end are detected by the same sensor. Also good.

  -When one of the two sensors fails, when the medium width is longer than the set width, when one of the first side end and the second side end is not connected to the other sensor that has not failed, A user may be inquired by displaying a message on the display unit as to whether or not an estimation process for detecting and estimating the other side end by calculation may be performed. This inquiry may be made by voice instead of or in addition to the message display.

  Although the medium detection device 80 is disposed below the transport path 30, it may be disposed above the transport path 30. Even in this configuration, the side edge of the medium P can be detected by reading the medium P downward by the two sensors 83, and the medium detection device 80 can be read in the transport direction Y with respect to the second path joining portion J2. By disposing the printing apparatus 11 at a position on the upstream side, the size of the printing apparatus 11 in the transport direction Y can be relatively shortened to reduce the size thereof.

  The medium information acquired by the sensor 83 detecting the side edge of the medium is one side edge position PE1 or PE2 in the width direction of the medium P, both side edge positions PE1, PE2, and the medium width (specified from the medium width). At least one of the print range in the width direction X). For example, the medium information may be only one of one side edge position, both side edge positions, medium width, and printing range. Further, the content of the medium information acquired from the side edge detection result may be different depending on the print mode, or there may be a print mode in which the side edge detection process is not performed. In the case where only one side edge is detected, the carriage 82 has a maximum width if it is configured to detect one side edge of the medium in a certain printing mode and to detect the other side edge of the medium in another printing mode. It is necessary to be able to move the moving range in which both sides of the medium can be detected.

  In addition to the side edge of the medium P, the sensors 83A and 83B may detect at least one of the front end and the rear end in the transport direction Y. For example, before the medium P is fed to the reading position, the carriage 82 is moved from the home position HP and the sensor 83 is placed on standby at a position where the front end in the transport direction Y of the medium P can be detected. The tip is detected when it is sent. After detecting the leading edge, the carriage is moved to one side (for example, the right side) in the width direction X to detect one side edge, and then the carriage is moved to the other side (for example, the left side) in the width direction X. The other side is detected. For example, the control unit 120 may control the start timing of a predetermined operation such as a medium skew removal operation based on the front end detection information obtained by detecting the front end of the medium P. In this case, for example, the sensor 79 can be eliminated. Further, the control unit 120 may grasp the position (transport position) in the transport direction Y of the medium P based on the leading edge detection information, and control the print start timing by the print head 34.

  When the sensor 83 is an optical sensor, it is not limited to the light reflection type, and may be a light transmission type. For example, a light source that can be moved together with the sensor 83 or a linear light source that can be lit in a range over the movement range of the sensor is disposed at a position facing the medium detection device 80 across the conveyance path, and receives light from the light source. The side edge of the medium may be detected by switching between the state and the non-light-receiving state where light cannot be received due to being blocked by the medium.

The sensor 83 may be replaced with an optical sensor and may be a contact type sensor. Even the contact sensor can detect the side edge of the medium.
The power source of the medium detection device 80 may be a DC motor (direct current motor) instead of a stepping motor. In the case of a DC motor, for example, a linear encoder or a rotary encoder capable of outputting a number of pulse signals proportional to the moving distance of the carriage 82 is provided, and the position of the carriage 82 is indicated by counting the pulse edges of the pulse signals output from the encoder. A counter capable of counting values may be provided. And a control part should just acquire the side edge position which sensors 83A and 83B detected based on the count value of a counter.

  -It replaces with the structure which arranges the window part 88 along the width direction X, and it is good also as a structure which arrange | positions one window part in the area | region corresponding to the movement path | route of a sensor. Further, the number of the windows 88 arranged along the width direction X is not limited to two, and may be three or more, such as three or four. In this case, what is necessary is just to arrange | position a several window part in the position which can detect the side edge of the both sides of the multiple types of medium P from which width differs. For example, a plurality of windows may be arranged at positions symmetrical to the width direction X with respect to the width center (center line) of the medium P to be conveyed.

  The reverse feed path 56 (or the third feed path 93) is replaced with a reverse path that joins the merging portion via the print head 34 side (upper side) with respect to the transport path 30 and is instead of the transport path 30. A reversing path that merges with the merge portion via the print head 34 side (lower side) may be used.

  -Extend the movable distance of the carriage 82 by a length that allows detection of both side edges PE1 and PE2 of the maximum width medium P with only one of the two sensors, and the number of sensors to be used according to the width of the medium P. It is good also as a structure which does not need to switch. In this case, the process of comparing the width based on the width information with the set width can be abolished, and both sides of the medium can be detected by only one sensor, and both sides of the medium can be detected by only the other sensor when a failure occurs.

  The number of sensors 83 provided on the carriage 82 of the medium detection device 80 may be one. In this case, the movable distance of the carriage 82 may be extended by a length capable of detecting both side edges of the maximum width medium.

  The medium detection device 80 may be arranged at a position where the reading position is upstream in the transport direction Y with respect to the second path junction portion J2 and downstream in the transport direction Y with respect to the second junction portion 76. Even in this configuration, the medium detection device 80 is separated at the reading position from the third feeding path 93 where the medium P printed on one side is re-fed, so that printing performed on one side is performed. Ink hardly adheres to the window 88. Therefore, it is easy to suppress a decrease in side edge detection accuracy due to this type of ink stain.

  The medium detection device 80 may be disposed at a position where the reading position is upstream in the transport direction Y with respect to the first path junction portion J1 and downstream in the transport direction Y with respect to the first junction portion 75. Even in this configuration, the medium detection device 80 reads the medium P fed through either of the two feeding paths 45 and 48 by the common one medium detection device 80 and detects the side end thereof. Can do. In this case, since the feeding paths 91 and 92 with different media pass relatively close at the place where the first joining portion 75 joins, if the sensor 83 having a relatively long detectable distance is selected, the required side edge detection accuracy is obtained. Can be secured.

  The medium detection device 80 may be disposed at a position where the reading position is upstream of the first joining portion 75 in the transport direction Y. In this case, if the medium detection device 80 is arranged for each of the plurality of feeding paths 91 and 92, the side edge of each medium P passing through the different feeding paths 91 and 92 can be detected. Further, the side detection may be performed by the medium detection device 80 only for a medium fed through one of the plurality of feeding paths 91 and 92.

A plurality of medium detection devices 80 may be provided so that the side edges of the medium P can be detected at a plurality of locations on the conveyance path of the medium P.
Only a part of the first feeding part 41 is provided on the cover 23, only a part of the second feeding part 42 is provided on the cover 23, a part of the first feeding part 41 and the second feeding part May be provided on the cover 23. Further, the cover may be configured not to include the feeding tray 22 as an example of the medium loading unit.

  The medium loading unit may be only one of the cassette 21 and the feeding tray 22. Further, the number of cassettes 21 is not limited to a plurality and may be one. Furthermore, the number of feeding trays is not limited to one, and a plurality of feeding trays may be provided.

  -The printing device is not limited to a line printing type printing device (line printer) or a serial printing type printing device (serial printer), but lateral printing in which the carriage can move in two directions, the main scanning direction and the sub-scanning direction. A printing apparatus (lateral printer) may be used. Even when the present invention is applied to this type of serial printer or lateral printer, the size in the width direction X and the conveyance direction Y of the printing device can be made relatively short when the medium detection device is provided.

  Each functional unit constructed in the control unit is not limited to being realized by software by a computer that executes a program. For example, an electronic circuit such as an FPGA (field-programmable gate array) or an ASIC (Application Specific IC) It may be realized by hardware, or may be realized by cooperation between software and hardware.

  The medium is not limited to paper, and may be a resin film or sheet, a resin-metal composite film (laminate film), a woven fabric, a nonwoven fabric, a metal foil, a metal film, a ceramic sheet, or the like.

The printing apparatus is not limited to a multifunction peripheral, and may be a printer that does not include a scanner unit but has a printer unit.
The printing apparatus is not limited to an ink jet printer, and may be a dot impact printer, a thermal transfer printer, or an electrophotographic printer.

  The printing apparatus is not limited to a printing apparatus that performs printing on a medium such as paper, but may be a 3D printer that forms a three-dimensional solid object by discharging resin droplets onto a medium including a base material of a component. Even with this type of printing apparatus, the size of the apparatus main body can be made relatively short, and a highly accurate three-dimensional solid object can be formed on a medium such as a base material.

  DESCRIPTION OF SYMBOLS 11 ... Printing apparatus, 12 ... Printer part, 14 ... Operation panel, 15 ... Display part, 16 ... Operation part, 20 ... Apparatus main body (main body), 21 ... Cassette as an example of medium mounting part, 22 ... Medium mounting Feed tray as an example of a unit, 23... Cover, 25 .. print mechanism unit, 30... Transport path, 31 .. transport path, 32... Transport unit as an example of a transport unit, 33. 35 ... feed mechanism, 36 ... conveying path, 37 ... conveying mechanism, 38 ... discharge mechanism, 41 ... first feeding unit as an example of feeding unit, 42 ... second feeding unit, 43 ... first 3 feeding unit, 44 ... feeding roller pair, 45 ... first feeding path, 46 ... transport roller pair, 48 ... second feeding path as an example of transport path, 49 ... pickup roller, 50 ... separation roller, 53 ... Branch mechanism, 54 ... Branch conveyance path, 55 ... Conveyance b , 56... Reverse feed path as an example of a double-sided printing path, 57... Reverse feed roller pair, 58... Belt transport mechanism, 65 ... main body side feed mechanism section, 66 ... cover side feed mechanism section, 71. Guide member as an example of medium guide member, 71A, 71B ... Medium guide surface, 71C ... Light reflecting surface, 75 ... First merging portion, 76 ... Second merging portion as an example of merging portion and passage merging portion, 77 ... First common feed path constituting an example of the conveyance path, 78... Second common feed path, 80... Medium detection device, 81... Casing, 81 A... Medium guide section, 81 B. 83, 83A ... Sensor (first sensor), 83, 83B ... Sensor (second sensor), 84, 85 ... Rail part, 86 ... Pulley, 87 ... Belt, 88 ... Window part, 89 ... Flexible flat cable, 90 ... Position sensor 91 ... 1st feeding path, 92 ... 2nd feeding path, 93 ... 3rd feeding path as an example of duplex printing path, 103 ... Electric motor, 106 ... Light emitting part, 107 ... Light receiving part, 114, 118 DESCRIPTION OF SYMBOLS ... Positioning mechanism, 120 ... Control part, 121 ... 1st feed motor, 122 ... 2nd feed motor, 123 ... 1st conveyance motor, 124 ... Motor for belts, 125 ... 2nd conveyance motor, 126-131 ... Motor Drive circuit 141 Width information acquisition unit 142 Carriage control unit 143 Failure detection unit 144 Detection processing unit 145 Counter 146 Operation unit P, SP, LP ... Medium, J1 First path Junction unit, J2 ... Second path junction unit as an example of a junction unit, PD ... print job data, HP ... home position, AP ... anti-home position, L1 ... center distance, SA, SB ... sensor detection Out signal, SH ... detection signal of position sensor, t1, t2, t3 ... time, PE1 ... first side end (side end), PE2 ... second side end (side end), Y ... transport direction, X ... width direction .

Claims (10)

A medium placement unit capable of placing a medium;
A transport unit configured to transport a medium from the medium mounting unit;
A print head for printing on the medium;
A medium detection device that is arranged upstream of the print head in the conveyance direction of the medium and that can read the medium in a width direction intersecting the conveyance direction and detect side edges on both sides of the medium;
The transport unit transports a medium from the medium placement unit along a path that passes through a position where the print head can print, and a medium on which one surface is printed by the print head through the transport path. A double-sided printing path that reverses to the other surface of the medium in a printable direction and returns to the junction located upstream in the transport direction with respect to the print head in the transport path;
The printing apparatus according to claim 1, wherein a reading position of the medium detection device is located on an upstream side in the transport direction with respect to the joining portion with the duplex printing path in the transport path. A further provided cover that can be opened and closed at a position upstream of the print head in the transport direction relative to the main body of the printing apparatus;
The cover includes at least a part of a feeding unit capable of feeding a medium placed on at least one of the plurality of medium placing units, and a conveyance path for guiding the medium along the conveyance path. And a medium guide member forming at least a part of a passage merging portion where a double-sided printing passage for guiding the medium to the merging portion along the double-sided printing path is assembled. The printing apparatus according to claim 1. A plurality of the medium placement sections are provided, and the first merge section where at least two feeding paths through which the medium is fed from different medium placement sections merges is more than the second merge section as the merge section. Is also located upstream in the transport direction,
The printing apparatus according to claim 1, wherein the reading position is located downstream of the first merging portion and upstream of the second merging portion in the transport direction.   The reading position is located on the downstream side in the transport direction with respect to a first path joining portion where at least two feeding paths of the medium fed through the at least two feeding paths merge. The printing apparatus according to claim 3.   The reading position of the medium detection device is a path merging where a conveyance path that guides the medium along the conveyance path and a duplex printing path that guides the medium to the merging portion along the duplex printing path. The printing apparatus according to any one of claims 1 to 4, wherein the printing apparatus is located upstream of the printing unit in the transport direction.   The medium detection device includes a carriage that is movable in the width direction at a position upstream of the print head in the transport direction, a sensor provided on the carriage, and the carriage that has the maximum width of the medium. The printing apparatus according to claim 1, further comprising: a power source that moves the side edges on both sides within a detectable moving range. The carriage is provided movably in the width direction at a position opposite to the print head side with respect to a conveyance path of a medium conveyed by the conveyance unit,
The printing apparatus according to claim 6, wherein the sensor is an optical sensor capable of reading the medium from a position opposite to the print head with respect to the transport path. The medium detection device includes a housing that houses the carriage and the optical sensor,
The housing includes a medium support unit that supports a medium transported from the medium placement unit in a portion facing the transport path,
The printing apparatus according to claim 7, wherein the medium support portion is provided with a light transmissive window in a region corresponding to a movement path of the optical sensor accompanying the movement of the carriage. . The sensor is a light reflective sensor,
A medium guide member for guiding the medium along the transport path is disposed at a position facing the sensor travel path across the transport path, and the medium guide member is a portion facing the sensor travel path. The printing apparatus according to claim 7, wherein a light reflecting surface is formed.   The medium placement unit is characterized in that it is at least one of a cassette capable of accommodating a plurality of media placed in a stacked state and a feeding tray capable of placing one or more media. The printing apparatus according to any one of claims 1 to 9.

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