Printer and printer control method

A printer capable of preventing clogging the printhead nozzles due to paper dust produced from sprocket holes in continuous paper, and preventing the printhead from ejecting ink droplets except on the continuous paper, has a printhead that ejects ink droplets toward continuous paper having sprocket holes formed along both sides of the paper width; a cover member that covers the edge part of the width of the continuous paper where sprocket holes are formed in the range of the printhead in the conveyance direction of the continuous paper, and can move in the paper width direction; and a detection mechanism that detects the position of the cover member in the paper width direction.

Priority is claimed under 35 U.S.C. §119 to Japanese Application No. JP 2011-074378 filed on Mar. 30, 2011, which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a printer that prints by ejecting ink droplets onto continuous paper, and to a method of controlling the printer.

2. Related Art

Inkjet printers that print by ejecting ink droplets onto continuous paper having sprocket holes formed at a specific interval along both edges of the paper width are known from the literature. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2005-1303. The inkjet printer described in JP-A-2005-1303 has a line head (printhead) with nozzles formed across the entire length of the paper width, and prints to continuous paper by ejecting ink droplets from the line head. This inkjet printer also has a tractor that conveys the continuous paper by engaging the sprocket holes in the continuous paper.

Paper dust is easily produced from the sprocket holes when using continuous paper with sprocket holes. The paper dust produced from the sprocket holes can easily clog the nozzles of the printhead in the inkjet printer, easily resulting in dropped dots and a drop in print quality. Also, inkjet printers that print on continuous paper generally print to continuous paper based on print commands from a printer driver. As a result, if the width of the continuous paper specified by the printer driver and the actual width of the continuous paper set in the inkjet printer differ, the printhead may eject ink droplets outside the width of the continuous paper.

SUMMARY

A printer according to at least one embodiment of the present invention can prevent clogging of the nozzles in the printhead by paper dust from the sprocket holes in continuous paper while also preventing the printhead from ejecting ink droplets at places other than on the continuous paper.

Another aspect of at least one embodiment of the invention is a printer control method that can prevent the printhead from ejecting ink droplets to places outside the continuous paper even in a printer that can prevent clogging of the nozzles in the printhead by paper dust from the sprocket holes in continuous paper.

One aspect of at least one embodiment of the invention is a printer having: a printhead that ejects ink droplets toward continuous paper having feed holes formed therein at a specific interval along both edge parts of the paper width; a cover member that covers an edge part of the width of the continuous paper where the feed holes are formed in the conveyance direction of the continuous paper at least in the printhead installation area and can move in the paper width direction; a detection mechanism that detects a position of the cover member in the paper width direction; and a paper edge position detection means that determines the position of an edge of the continuous paper in the paper width direction based on the detected position of the cover member in the paper width direction.

A printer according to at least one embodiment of the invention has a cover member that covers an edge part of the width of the continuous paper in which feed holes are formed in the printhead installation area at least in the continuous paper conveyance direction. As a result, paper dust produced at the feed holes can be prevented from floating up toward the printhead by the cover member. Paper dust produced in the feed holes can therefore be prevented from sticking to the nozzles of the printhead, and clogging of the printhead nozzles by paper dust can be prevented as a result.

In addition, because the cover member can move in the paper width direction, the feed holes can be covered by the cover member when the width of the continuous paper used in the printer changes by moving the cover member in the paper width direction. Clogging the nozzles of the printhead by paper dust can therefore be prevented even if the width of the continuous paper used in the printer changes.

The printer of at least one embodiment of the invention also has a detection mechanism that detects the position of the cover member in the paper width direction, and a paper edge position detection means that determines the position of an edge of the continuous paper in the paper width direction based on the detected position of the cover member in the paper width direction.

The position of the edge of the continuous paper in the paper width direction can therefore be detected based on the detected position of the cover member even if the widthwise edge of the continuous paper where the feed holes are formed is covered by the cover member, and the width of the continuous paper set in the printer can be determined. The invention can therefore print to continuous paper by the printhead within the identified range of the paper width, and the printhead can be prevented from ejecting ink droplets outside of the width of the continuous paper.

A printer according to the invention preferably also has a tractor that can move in the paper width direction and conveys the continuous paper while engaging tractor pins sequentially in the feed holes; and a connecting member that connects the tractor and the cover member; the cover member and the tractor moving together in the paper width direction.

If the tractor is moved in the paper width direction when the width of the continuous paper used in the printer changes, the cover member moves with the tractor in the paper width direction. The feed holes can therefore be covered by the cover member even when the width of continuous paper used in the printer changes by simply moving the tractor. The cover member can therefore also be easily moved, and the cover member can be reliably moved when the continuous paper changes.

Because the cover member and tractor move together in the paper width direction, the distance between the tractor pins and the cover member in the paper width direction is always substantially the same, and as a result the distance between the cover member and the feed holes of the continuous paper engaged by the tractor pins is always substantially constant in the paper width direction. More specifically, the distance between the edge of the continuous paper and the cover member in the paper width direction is always substantially constant. The position of the edge of the continuous paper can therefore be determined with good precision based on the result of detecting the position of the cover member, and the width of the continuous paper can be determined with good precision as a result.

The detection mechanism is a reflective photodetector including a light-emitting device and a photodetection device that detects light emitted from the light-emitting device and reflected by the cover member.

This configuration enables detection of the position of the cover member by the detection mechanism by positioning the detection mechanism above the cover member. The detection mechanism can also be positioned more easily when the detection mechanism is a transmissive photodetector having the light-emitting device and photodetector disposed with the cover member therebetween.

A printer according to another aspect of at least one embodiment of the invention preferably also has a carriage on which the printhead is mounted and which can move in the paper width direction; the detection mechanism being disposed to the carriage.

This configuration enables positioning the detection mechanism near the printhead. The edge of the continuous paper detected from the detection result of the detection mechanism, and the edge of the part of the continuous paper to which the printhead actually ejects ink droplets, can therefore not shift easily. As a result, the printhead can be reliably prevented from ejecting ink droplets outside of the continuous paper. The position of the cover member that can move in the paper width direction can also be detected using a single detection mechanism.

A printer according to another aspect of at least one embodiment of the invention preferably also has a plurality of platen sections that are disposed in the printhead installation area in the conveyance direction and separated in the paper width direction; a cover reflector that reflects light and is disposed on the cover member; and a platen reflector that reflects light and is disposed on a platen section, wherein the width of the cover reflector in the paper width direction and the width of the platen reflector in the paper width direction are different, and the detection mechanism is a reflective photodetector including a light-emitting device and a photodetection device that detects light emitted from the light-emitting device and reflected by the cover reflector or the platen reflector.

Further preferably, the carriage moves so that the detection mechanism crosses the cover reflector and the platen reflector; and the paper edge position detection means differentiates whether the cover reflector or the platen reflector was detected, and detects the position of the cover member in the paper width direction, based on the time that the photodetection device detects light reflected by the cover reflector, and the time that the photodetection device detects light reflected by the platen reflector.

Because the width of the cover reflector and the width of the platen reflector in the paper width direction are different, the time that the photodetector detects light reflected by the cover reflector and the time that the photodetector detects light reflected by the platen reflector are different. The cover member and the platen section can therefore be differentiated, and the position of the cover member can be appropriately detected, based on the photodetection time of the photodetector even if the section platen is in the area where the printhead is located.

Another aspect of at least one embodiment of the invention is a method of controlling a printer that has a printhead that ejects ink droplets toward continuous paper having feed holes formed therein at a specific interval along both edge parts of the paper width, and a cover member that covers an edge part of the width of the continuous paper where the feed holes are formed in the conveyance direction of the continuous paper at least in the printhead installation area and can move in the paper width direction, the control method including steps of: detecting a position of the cover member in the paper width direction; and determining the position of an edge of the continuous paper in the paper width direction based on the detected position of the cover member in the paper width direction.

Because the edge part of the width of the continuous paper in which feed holes are formed is covered by the cover member in the printhead installation area at least in the continuous paper conveyance direction, paper dust produced at the feed holes can be prevented from sticking to the nozzles of the printhead, and clogging of the printhead nozzles by paper dust can be prevented as a result.

In addition, because the cover member can move in the paper width direction, the feed holes can be covered by the cover member even when the width of the continuous paper used in the printer changes by moving the cover member in the paper width direction. Clogging the nozzles of the printhead by paper dust can therefore be prevented even if the width of the continuous paper used in the printer changes.

The invention detects the position of the cover member in the paper width direction, and determines the position of the edge of the continuous paper in the paper width direction based on the detected position of the cover member in the paper width direction. As a result, even if the widthwise edge of the continuous paper where the feed holes are formed is covered by the cover member, the position of the edge of the continuous paper in the paper width direction can be determined based on the result of detecting the position of the cover member, and the width of the continuous paper set in the printer can be determined. The printer control method according to the invention can therefore print to continuous paper by the printhead within the identified range of the paper width, and as a result can prevent the printhead from ejecting ink droplets outside of the width of the continuous paper, even in a printer that can prevent clogging of the printhead nozzles due to paper dust produced from the feed holes in continuous paper.

DESCRIPTION OF EMBODIMENTS

A printer according to a preferred embodiment of the invention is described below with reference to the accompanying figures.

General Configuration of the Printer

FIG. 1is an oblique view of a printer1according to a preferred embodiment of the invention.FIG. 2is a schematic longitudinal view showing main parts of the printer1.FIG. 3is an oblique view of the printer1shown inFIG. 1with the case5removed.FIG. 4is an oblique view of the printer5from a different angle with the case5removed.

The printer1is a device that prints on continuous paper2. Sprocket holes (feed holes)2aare formed at a specific interval along the length of both widthwise edges of the continuous paper2. The printer1has a printer unit3, a tractor4disposed at the back end of the printer unit3, and a printer case5that covers the printer unit3and tractor4. The continuous paper2is conveyed from the back of the printer into the printer unit3by the tractor4and printed on, and is then discharged from the front of the printer unit3. The direction between the back and front of the printer is thus the conveyance direction of the continuous paper2. The direction between the left and right sides of the printer is also the paper width direction of the continuous paper2.

A paper conveyance path6through which the continuous paper2is conveyed is formed inside the printer unit3straight between the back and front of the printer. A printhead7is disposed inside the printer unit3. The printhead7can be an inkjet head that ejects ink droplets onto the continuous paper2. If the print head7is an ink jet head, a plurality of nozzles that discharge ink droplets are formed in the printhead7. The printhead7is disposed above the paper conveyance path6. The printhead7is mounted on a carriage8. The carriage8can travel sideways in the paper width direction by drive power from a drive mechanism including a drive motor, pulley, and belt.

A plurality of platen sections9that are separated in the paper width direction are disposed inside the printer unit3. In this embodiment, for example, five platen sections9are disposed inside the printer unit3. The platen sections9are disposed below the paper conveyance path6. The platen sections9and printhead7are disposed at substantially the same position in the longitudinal direction of the printer. More specifically, as shown inFIG. 2, when seen from the side of the printer, the platen sections9and printhead7are disposed vertically opposite each other with a specific gap therebetween. In this embodiment of the invention, the plural platen sections9determine the printing area P where the printhead7prints on the continuous paper2. The printing area P is also where the printhead7is located in the longitudinal direction of the printer.

A paper feed roller10for feeding the continuous paper2to the printing area P is disposed between the printing area P and the tractor4. A pressure roller11for pressing the continuous paper2to the paper feed roller10contacts the paper feed roller10from above. The pressure roller11is pressed to the paper feed roller10with a specific urging force. A discharge roller12for discharging the printed continuous paper2is disposed toward the front of the printer from the printing area P. A pressure roller13for pressing the continuous paper2to the discharge roller12contacts the discharge roller12from above. The pressure roller13is pressed with a specific urging force to the discharge roller12.

A tractor4is disposed on both left and right sides of the printer. Each tractor4has tractor pins15that are inserted to the sprocket holes2aof the continuous paper2. The tractor pins15are formed at a specific interval on the outside surface of the tractor belt16. The tractor belt16is mounted on a drive pulley17and a follower pulley18. In this embodiment of the invention a tractor4can move sideways in the printer so that different widths of continuous paper2can be conveyed and printed. However, only the tractor4on one side of the printer is moved when adjusting to the width of the continuous paper2, and the tractor4on the other side of the printer does not move. The tractor4disposed on the one side of the printer is referred to below as tractor4A.

A square through-hole is formed in the center of the drive pulley17passing through in the direction between the sides of the printer. A drive shaft19that is driven rotationally by drive power from a drive motor not shown passes through this through-hole. The drive shaft19is rotatably supported on the frame of the printer1with the axis of the shaft aligned in the paper width direction. The drive motor is connected to one end of the drive shaft19through a power transfer mechanism including pulleys and belts, for example. The drive shaft19is a square rod, and when the drive shaft19turns, the drive pulley17also turns in conjunction with the drive shaft19.

A round guide hole is formed in the center of the follower pulley18passing through in the paper width direction. A round guide shaft20that guides the tractor4A sideways to the printer is inserted to this guide hole. The guide shaft20is fixed to the printer1frame with its axis extending in the paper width direction. The follower pulley18can rotate on the guide shaft20. The follower pulley18in the paper width direction along the guide shaft20. Note that the drive pulley17of the tractor4A can also move in the paper width direction along the drive shaft19, and the drive shaft19also functions as a guide shaft that guides the tractor4A in the paper width direction.

To convey the continuous paper2by the tractor4, the continuous paper2is set so that the tractor pins15are inserted in the sprocket holes2a. The drive shaft19and drive pulley17are then turned by drive power from the drive motor, causing the tractor pins15to sequentially engage the sprocket holes2aand convey the continuous paper2.

When printing to continuous paper2, the printer1alternately performs a printing operation in which the printhead7moves in the scanning direction (that is, sideways to the printer) perpendicularly to the conveyance direction of the continuous paper2and prints, and a paper feed operation that advances the continuous paper2in specific increments.

Configuration of the Cover Member, Tractor, and Connecting Member

FIGS. 5A and 5Bshow the configuration of the printer1in the printing area P.FIG. 6is an oblique view of the movable cover member21A, tractor4A, and connecting member27from above.FIG. 7is an oblique view of the movable support member24, tractor4A, and connecting member27from below.

As shown inFIGS. 5A and 5B, the printer1has a cover21that covers the sprocket holes2afrom above in the printing area P. A cover21is disposed on both the left and right sides of the printer. When seen from the side of the printer, the cover21is located below the printhead7. In this embodiment of the invention, the cover21disposed on one side of the printer can move sideways on the printer in order to cover the sprocket holes2aof different widths of continuous paper2. The cover21disposed on the other side of the printer is stationary and does not move left and right.

The cover21is made from a member that reflects light. The cover21could be made by bending a thin steel plate into the desired shape, for example. The cover21has a cover part21athat covers the sprocket holes2afrom above. The cover part21acovers the entire sprocket hole2aarea from above in the paper width direction. The cover part21ais formed extending from the outside to the inside from the left and right sides of the printer, and covers both edge parts of the continuous paper2including the edges of the continuous paper2at the sides of the paper. Note that cover part21ain this embodiment of the invention is a cover reflector that is part of the cover21and reflects light.

The stationary-side cover21(cover member21B below) on the other side of the printer width is fastened to the top of the support member22that supports the widthwise edge of the continuous paper2from below as shown inFIGS. 5A and 5B. The support member22is made from a black plastic or other member that is a poor light reflector (or does not reflect light). This support member22is fastened to the frame of the printer1. The top surface of the inside part of the support member22in the transverse direction of the printer is one of five platen sections9.

The movable cover21disposed on one side of the printer (cover member21A below) is fastened to the top surface of a support member24that supports the widthwise edge part of the continuous paper2from below. The support member24is made from a black plastic or other member that is a poor light reflector (or does not reflect light). The top surface of the inside part of the support member24in the transverse direction of the printer is one of five platen sections9. A tapered part24athat slopes so that the width of the support member24becomes narrower in the paper width direction with proximity to the bottom is formed on both widthwise sides of the support member24. As shown inFIG. 7, two protruding parts24bthat protrude toward the back are formed at the back of the support member24. A round guide hole is formed in the protruding parts24bpassing therethrough in the paper width direction. A round guide shaft26that guides the cover member21A and support member24widthwise to the printer passes through the guide hole. The guide shaft26is affixed to the printer1frame with its axis widthwise to the printer.

The tractor4A and cover member21A are connected by a connecting member27. More specifically, the tractor4A and support member24are connected by the connecting member27. As a result, the tractor4A and cover member21A move together sideways to the printer. The connecting member27has a tractor mount27aon which tractor4A is mounted, and an engaging part27bthat engages the support member24. The tractor mount27aand engaging part27bare connected by the connecting part27c.

The engaging part27bincludes a pair of stops27dformed so that the two protruding parts24bof the support member24are therebetween sideways to the printer. A slot27ethat is U-shaped when seen from the side of the printer is formed in the stops27d. The guide shaft26is inserted to this slot27e. The slot27eis formed so that the cover member21aside of the stops27dis open.

When the width of the continuous paper2used in the printer1is changed, the user holds a particular part of the tractor4A and moves the tractor4A sideways to the printer. When the tractor4A moves sideways to the printer, the inside face of the stops27dof the connecting member27sideways to the printer contact the outside face of the protruding parts24bsideways to the printer, and the cover member21A moves with the support member24sideways to the printer.

Configuration of the Platen Sections and Adjacent Area

FIG. 8is a plan view of a platen section9and the support member30.FIG. 9is a section view through E-E inFIG. 8.

Part of the support member22is thus one platen section9of the five platen sections9, and part of support member24is one platen section9of the five platen sections9. The remaining three platen sections9are supported by support members30disposed at a specific interval widthwise to the printer. The platen sections9supported by the support members30can move vertically relative to the support member30. Each platen section9supported by a support member30is urged upward by a compression spring31. A platen section9supported vertically movable by a particular support member30is referred to as a movable platen9A below.

The movable platen9A is made from a black plastic or other member that is a poor light reflector (or does not reflect light). As shown inFIG. 9, the movable platen9A is hollow. A tubular spring insertion portion9athat is inserted into the top end of the compression spring31is formed on the inside of the movable platen9A. A flange9bprotruding to the outside widthwise to the printer is formed at the bottom end of the movable platen9A. A sloped face9cis formed at the top end of the movable platen9A so that the width of the movable platen9A widthwise to the printer narrows towards the top.

As shown inFIG. 9, the support member30is shaped like a box with an open top. The support member30is fastened to the printer1frame. A guide member30athat guides the flange9bvertically is formed on the outside of the support member30widthwise to the printer. The guide member30ais shaped like a channel engaged by the flange9b, and restricts movement of the flange9blongitudinally and sideways to the printer. A stop30bthat limits the range of upward movement of the movable platen9A is formed contacting the top of the flange9bat the top end of the guide member30a.

The bottom end of the compression spring31contacts the top of the bottom30cof the support member30. The top end of the compression spring31contacts the inside part of the top end of the movable platen9A. The spring insertion portion9aof the movable platen9A is inserted to the top end of the compression spring31.

Thus configured, the cover member21A moves widthwise relative to the printer when the width of the continuous paper2used in the printer1changes. For example, when the cover member21A moves to the other side widthwise to the printer (toward cover member21B), the tapered part24aof the support member24and the sloped face9cof the movable platen9A touch, and the movable platen9A gradually retreats down against the urging force of the compression spring31as shown inFIG. 5B. When the cover member21A then moves to the outside from this position widthwise relative to the printer, the retracted movable platen9A rises to where the flange9band the stop30bcontact due to the urging force of the compression spring31as shown inFIG. 5A. The movable platen9A can thus move vertically so that the cover member21A can move sideways to the printer.

As shown inFIGS. 8 and 9, a support plate32made from a light-reflecting member is attached to the top end of the platen section9. This support plate32could be a thin steel plate, for example. The bottom of the continuous paper2passing the printing area P contacts the support plate32. The support plate32in this embodiment is a platen reflection unit that is formed on the platen section9and reflects light.

Structure and Method of Detecting the Position of the Edge of Continuous Paper

FIG. 10shows the printhead7, carriage8, and movable cover member21A from the side of the printer.FIG. 11is an enlarged plan view of the movable cover member21A and adjacent area.

As described above, only the tractor4A on the one side of the printer moves, and the tractor4on the other side of the printer does not move, when the continuous paper2width is changed. As a result, the position of the paper edge on the other side of the printer is always the same, even when the continuous paper2width changes. However, when the continuous paper2width is changed, the position of the paper edge2bon the one side of the printer changes. Therefore, in order to prevent the printhead7from ejecting ink droplets anywhere other than on the continuous paper2in the paper width direction after the continuous paper2width is changed, the position of the paper edge2bof the continuous paper2must be determined. However, because the paper edge2bis covered by the cover part21aof the cover member21A, the paper edge2bcannot be directly detected in the printing area P.

This embodiment of the invention therefore detects the position of the cover member21A in the transverse direction, and determines the position of the paper edge2bfrom this detected cover member21A. The printer1has a detection mechanism35for detecting the position of the cover member21A in the transverse direction, and a control unit (edge position determination means)36connected to the detection mechanism35.

The detection mechanism35is an reflective optical sensor having a light-emitting device and an adjacently disposed photodetector device. The detection mechanism35is disposed to the bottom of the carriage8, and moves sideways. As shown inFIG. 11, the detection mechanism35is disposed to the carriage8so that the detection mechanism35passes over the support plate32attached to the top of the platen section9and the rear end part of the cover part21aof the cover member21A. The light-emitting device of the detection mechanism35emits light downward, and the photodetector senses light reflected by the cover part21a, for example.

Because the cover member21A moves sideways in conjunction with the tractor4A as described above, the distance between the tractor pins15of the tractor4A and the inside side edge21bof the cover part21ais substantially constant. The distance in the transverse direction between the sprocket holes2aengaged by the tractor pins15of the tractor4A and the edge21bof the cover part21ais therefore substantially constant, and the distance L (seeFIG. 11) between the edge2bof the continuous paper2and the edge21bof the cover part21ais also substantially constant.

Based on output from the detection mechanism35, the control unit36in this embodiment of the invention detects the edge21b, and determines the position of the edge2bof the continuous paper2based on the detected position of edge21b. For example, because the output level of the photodetector of the detection mechanism35changes when the detection mechanism35passes over the edge21b, the control unit36detects the position of the edge21bfrom the position where the output level of the photodetector of the detection mechanism35changed, and determines the position of the paper edge2bby adding distance L to the detected position of the edge21b, for example. This embodiment of the invention determines the position of the paper edge2bbefore printing to the continuous paper2after the continuous paper2is set in the tractor4and the continuous paper2is supplied to the printing area P. The rear end part of the platen section9is therefore covered by the continuous paper2when the position of the paper edge2bis determined.

Main Effect of this Embodiment of the Invention

As described above, the printer1according to this embodiment of the invention has cover members21A,21B that cover the sprocket holes2afrom above in the printing area P. As a result, paper dust produced from the sprocket holes2acan be prevented by the cover members21A,21B from rising to the printhead7. Paper dust produced from the sprocket holes2acan thus be prevented from sticking to the nozzles of the printhead7, and printhead7nozzle clogging caused by paper dust can therefore be prevented.

Cover member21A in this embodiment of the invention can move widthwise relative to the printer, and the movable platen9A can move vertically so that movement of the cover member21A sideways to the printer is possible. As a result, the cover member21A can be moved in the paper width direction according to the width of the continuous paper2when the width of the continuous paper2used in the printer1changes even if the movable platen9A is in the printing area P. More specifically, the sprocket holes2acan be covered by the cover member21A even when the width of the continuous paper2changes. Paper dust produced from the sprocket holes2acan therefore be prevented from sticking to the nozzles of the printhead7even when the width of the continuous paper2changes, and clogging of the printhead7nozzles due to paper dust can be prevented.

This embodiment of the invention detects the position of the edge21bof the cover part21ain the printing area P, and determines the position of the paper edge2bof the continuous paper2from the detected edge21b. The position of the paper edge2bcan therefore be detected even when the paper edge2bis covered by the cover part21a, and the width of the continuous paper2that is set in the printer1can be determined. This embodiment can therefore use the printhead7to print to the continuous paper2within the range of the determined paper width, and as a result can prevent the printhead7from ejecting ink droplets outside of the continuous paper2. More specifically, because the position of the paper edge2bis determined in the printing area P, the position of the paper edge2bdetermined based on the detection result from the detection mechanism35matches the position of the paper edge2bin the part of the continuous paper2where the printhead7actually ejects ink droplets. This embodiment can therefore reliably prevent the printhead7from ejecting ink droplets outside of the continuous paper2.

In this embodiment the cover member21A and tractor4A are connected by the connecting member27, and the cover member21A moves sideways to the printer in conjunction with the tractor4A. More specifically, the cover member21A moves sideways in conjunction with the tractor4A moving according to the width of the continuous paper2that is used in the printer1. The sprocket holes2acan therefore be covered by the cover member21A by moving the tractor4A. Moving the cover member21A when the continuous paper2width changes is therefore simple. The cover member21A can therefore be moved reliably when the width of the continuous paper2changes.

Furthermore, because the cover member21A moves sideways in conjunction with the tractor4A in this embodiment, the distance L between the paper edge2bof the continuous paper2and the edge21bof the cover part21ais always substantially constant. The position of the paper edge2bcan therefore be determined with good precision based on the result of detecting the position of edge21b, and the width of the continuous paper2can be determined with good precision as a result.

The detection mechanism35in this embodiment is a reflective photodetector having a light-emitting device and an adjacently disposed photodetector. As a result, the position of the cover member21A can be detected using the detection mechanism35by attaching the detection mechanism35to the carriage8. The detection mechanism35can therefore be positioned more easily than when the detection mechanism is a transmissive photodetector having the light-emitting device and photodetector disposed with the cover member21A therebetween. In addition, because the detection mechanism35is attached to the carriage8in this embodiment, the position of the cover member21A, which can move in the transverse direction, can be detected using a single detection mechanism35.

Other Embodiments

The position of the paper edge2bis determined in this embodiment before printing to the continuous paper2after continuous paper2is set in the tractor4and the continuous paper2is supplied to the printing area P, but the position of the paper edge2bcould be determined after the continuous paper2is set in the tractor4and before the continuous paper2is supplied to the printing area P. In this case the detection mechanism35passes over the back ends of the platen sections9that are not covered by the continuous paper2. More specifically, in addition to the top of the cover part21a, the detection mechanism35passes over the top of the support plate32that is made of a light-reflecting member. As a result, the position of the edge21bof the cover part21acannot be detected only from the change in the output level of the photodetector of the detection mechanism35because the control unit36cannot differentiate between detection of the cover part21aand detection of the support plate32.

This can be solved by forming the cover part21aand the support plate32so that the width H1(FIG. 11) of the cover part21aand the width H2(FIG. 11) of the support plate32differ in the transverse direction. For example, the cover part21aand the support plate32could be formed so that the width H1of the cover part21ais greater than the width H2of the support plate32. If the carriage8then travels at a constant speed, and the carriage8moves so that the detection mechanism35crosses the cover part21aand support plate32, the detection time of the detection mechanism35when the cover part21ais detected (that is, the time that the photodetector of the detection mechanism35detects light reflected from the cover part21a), and the detection time of the detection mechanism35when the support plate32is detected (that is, the time that the photodetector of the detection mechanism35detects light reflected from the support plate32), will differ. Whether the cover part21awas detected or the support plate32was detected can therefore be differentiated based on the detection time of the detection mechanism35, and the position of the edge21bof the cover part21acan be detected from the position where the output level of the photodetector of the detection mechanism35changes when the cover part21ais detected. More specifically, the cover member21A and the platen sections9can be differentiated based on the detection time of the detection mechanism35even when a platen section9with a light-reflecting support plate32is located in the printing area P, and the position of the edge21bof the cover part21acan be appropriately detected. In addition, the position of the paper edge2bof the continuous paper2can be determined from the position of the detected edge21b.

The cover member21A and the tractor4A are connected by the connecting member27in the foregoing embodiment, but the cover member21A and the tractor4A do not have to be connected. In this case, if a contact that touches the paper edge2bof the continuous paper2is disposed on the cover member21A and the width of the continuous paper2changes, for example, the cover member21A can be positioned so that the paper edge2bcontacts this contact. Alternatively, if an index mark that is aligned with the paper edge2bis formed on a longitudinal end of the cover member21A, the cover member21A can be positioned transversely so that this index is aligned with the paper edge2b. The position of the paper edge2bcan also be determined in this case based on the result of detecting the position of the edge21bof the cover part21a.

The detection mechanism35detects the edge21bon the inside side of the cover part21ain the transverse direction in the foregoing embodiment, but the detection mechanism35could detect the edge21bon the outside side of the cover part21ain the transverse direction. The detection mechanism35could also detect any desired position of the cover member21A. In this case, the cover member21A is made from a member that reflects light poorly (or does not reflect light), and a mark made from a light-reflecting member for position detection is formed on the cover member21A.

The detection mechanism35in the foregoing embodiment is a reflective optical sensor, but the detection mechanism35could be a transmissive optical sensor. The detection mechanism35could also be a mechanical sensor that detects the position of the cover member21A by contacting the cover member21A. The detection mechanism35could also be rendered with a lever that contacts the cover member21A and moves, and an optical sensor that detects this lever.

A single detection mechanism35is disposed on the carriage8in the embodiment described above, but two or more detection mechanisms35could be disposed to the carriage8. Further alternatively, the detection mechanism35could be attached to the printer1frame instead of the carriage8. In this case, a plurality of detection mechanisms35are attached to the printer1frame.

The cover member21B is fastened to the printer1frame in the embodiment described above, but the cover member21B could be able to move in the transverse direction. In this case, the position of the cover member21B in the transverse direction could be detected, and the position of the other edge of the continuous paper2in the transverse direction can be detected in the same way as the position of the paper edge2bof the continuous paper2is detected above.