Cap unit and printer

Provided is a cap unit that can prevent or suppress collision between the drive gear and intermittent gear when the drive gear and intermittent gear begin to mesh. A cap unit 25 has a moving mechanism 28 that moves a cap 26. The moving mechanism 28 has an intermittent cam gear 36 with a cam channel 43; a drive gear 35; and a cap holder 45. The cap holder 45 includes a holding member 48 that holds the cap 26; a cam follower pin 49; a pin support mechanism 50 that supports the cam follower pin 49; and a coil spring 51 that urges the cam follower pin 49 toward the bottom 43a of the cam channel 43. A slope 57 is disposed to the bottom 43a of the cam channel 43. The cam follower pin 49 is on the slope 57 when meshing of the intermittent cam gear 36 and drive gear 35 is disengaged, and the intermittent cam gear 36 turns in conjunction with the cam follower pin 49 moving on the slope 57 due to the urging force of the coil spring 51.

BACKGROUND

1. Technical Field

The present invention relates to a cap unit that covers the ink nozzle face of a printhead with a cap. The invention also relates to a printer having the cap unit.

2. Related Art

When the ink nozzle face of a printhead is left exposed, water evaporates from the ink inside the ink nozzles. When the water content of the ink drops due to this evaporation of water, ink viscosity rises and ink nozzles become may become clogged. Inkjet printers therefore have a cap unit, and cover the ink nozzle face with a cap to suppress the evaporation of water from the printhead while in a standby mode waiting to print, for example.

The cap unit includes a cap, and a moving mechanism for moving the cap between a capping position where the cap covers the ink nozzle face of the printhead, and an open position where the cap is removed from the ink nozzle face. The moving mechanism transfers drive power from a motor as the drive source, through a drive power transfer mechanism, to the cap. JP-A-2004-203056 describes a drive power transfer mechanism having a drive gear to which motor rotation is transferred, and an intermittent gear that meshes with the drive gear.

When the drive power transfer mechanism includes an intermittent gear, contact between the tips of the gear teeth when the drive gear and intermittent gear begin to mesh produces noise and possibly damages the tips of the teeth. To avoid such problems, the intermittent gear must be turned in the same direction of rotation after the intermittent gear and drive gear disengage so that the tips of the teeth of the intermittent gear escape from the tips of the teeth of the drive gear, and the tips of the teeth of the intermittent gear and the tips of the teeth of the drive gear do not collide the next time the teeth begin to mesh.

When the drive power transfer mechanism includes an intermittent gear, if the intermittent gear turns due to an external disturbance such as an external shock after the intermittent gear and drive gear disengage, the chance of the tips of the teeth of the intermittent gear and the tips of the teeth of the drive gear colliding the next time the teeth begin to mesh increases.

The teeth start to mesh when the intermittent gear and drive gear begin to mesh turning in the opposite direction as the direction of rotation before the gears disengaged.

SUMMARY

An objective of the invention is to provide a cap unit that, when the drive power transfer mechanism that transfers drive power from a drive source to the cap has an intermittent gear, prevents or suppresses collision between the tips of the teeth of the intermittent gear and the tips of the teeth of the drive gear when the drive gear and intermittent gear begin to mesh. Another objective is to provide a printer having the cap unit.

To achieve the foregoing objective, a cap unit according to the invention includes: a cap; and a moving mechanism that moves the cap between a capping position covering the ink nozzle face of a printhead, and an open position removed from the ink nozzle face, the moving mechanism including an intermittent cam gear having a cam channel in an end face, a drive gear able to mesh with the intermittent cam gear, and a cap holder including a holding member that holds the cap, a cam follower pin able to move inside the cam channel, a pin support mechanism that supports the cam follower pin movably in a direction perpendicular to the bottom of the cam channel, an urging member that urges the cam follower pin toward the bottom; and a slope that deepens in the direction in which the cam channel extends disposed to the bottom of the cam channel. The cam follower pin being positioned on the slope when meshing of the intermittent cam gear and drive gear is disengaged; and the intermittent cam gear turning and the intermittent part of the intermittent cam gear moving into opposition with the drive gear in conjunction with the cam follower pin sliding down the slope and moving toward the bottom of the cam channel due to the urging force of the urging member.

In this configuration, immediately after the drive gear and intermittent cam gear disengage, the cam follower pin slides on the slope and moves in the direction toward the bottom of the cam channel due to the urging force of the urging member. As a result, because the intermittent cam gear turns, the tips of the teeth of the intermittent gear can escape from the tips of the teeth of the drive gear. In addition, because the cam follower pin of the cap holder is urged to the intermittent cam gear, rotation of the intermittent cam gear can be prevented or suppressed when, for example, an external shock is applied after the intermittent cam gear and drive gear disengage. Collision between the tips of the teeth of the intermittent gear and the drive gear the next time the gears start to mesh can therefore be prevented or suppressed.

A cap unit according to another aspect of the invention preferably also has a support mechanism that supports the cap holder movably radially to the intermittent cam gear.

This configuration can accurately move the cap between the capping position and open position.

In a cap unit according to another aspect of the invention, the slope is disposed to at least one of the end part of the inside circumference side, or the end part of the outside circumference side, of the cam channel, and the end side of the end part where the slope is disposed is deep.

While the toothed parts of the drive gear and intermittent cam gear are meshed, and the cam follower pin slides through the cam channel part between the inside circumference end and outside circumference end parts of the cam channel, the tips of the teeth of the intermittent gear can escape from the tips of the teeth of the drive gear after the drive gear and intermittent cam gear disengage.

In a cap unit according to another aspect of the invention, the cam channel has a wall at the end of the cam channel on the side where the slope is disposed; and when the drive gear and the intermittent part of the intermittent cam gear are in opposition, the cam follower pin contacts the wall.

In this configuration, after sliding on the slope and moving in the direction toward the bottom of the cam channel, and causing the intermittent cam gear to turn, the cam follower pin contacts the wall and stops rotation of the intermittent cam gear. The distance the intermittent cam gear turns after the drive gear and intermittent cam gear disengage can therefore be defined by the wall disposed beside the slope.

In a cap unit according to another aspect of the invention, the slope is disposed to the end part of the inside circumference side of the cam channel; the end of the cam channel on the inside circumference side is defined by the wall; and when the drive gear and intermittent cam gear are meshed, the drive gear is driven, and the intermittent cam gear turns in a first direction of rotation, the cam follower pin slides inside the cam channel and moves to the inside circumference side of the intermittent cam gear, and the cap held by the cap holder moves from the capping position to the open position.

By driving the drive gear, this configuration can move the cap from the capping position to the open position.

In a cap unit according to another aspect of the invention, when the intermittent part of the intermittent cam gear is opposite the drive gear after the intermittent cam gear turns in the first direction of rotation, the cap is preferably set to the open position.

When the cap is at the open position in this configuration, meshing of the drive gear and intermittent cam gear is disengaged, and the tips of the teeth of the intermittent gear can escape from the tips of the teeth of the drive gear.

Further preferably in a cap unit according to another aspect of the invention, the moving mechanism has an intermittent gear with a toothed part of the same diameter and same module as the intermittent cam gear, and is disposed coaxially and movably relative to the intermittent cam gear; a non-intermittent gear with a toothed part of the same diameter and same module as the intermittent cam gear, and disposed coaxially to the intermittent cam gear on the opposite side as the intermittent cam gear; and a friction clutch disposed between the intermittent gear and the non-intermittent gear, and transferring rotation of the non-intermittent gear to the intermittent gear. The drive gear can mesh with the non-intermittent gear and the intermittent gear. The intermittent gear has a contact part, at a position offset radially from the axis of rotation of the intermittent gear, capable of contacting the intermittent cam gear. The intermittent cam gear has a contacted part capable of contacting, at a specific circumferential position, the contact part from a second direction of rotation that is opposite the first direction of rotation. When the non-intermittent gear turns in the second direction of rotation, the intermittent gear meshes with the drive gear before the intermittent cam gear and turns, and the contact part contacts the contacted part, and causes the intermittent cam gear to turn with the intermittent gear with the phase of the toothed part of the intermittent gear matching the phase of the toothed part of the intermittent cam gear.

In this configuration, when the drive gear is driven to turn the non-intermittent gear in the second direction of rotation to move the cap from the open position to the capping position, rotation of the non-intermittent gear is transferred through the friction clutch to the intermittent gear, and the intermittent gear turns in the second direction of rotation. The intermittent gear meshes with the drive gear before the intermittent cam gear. Because a friction clutch intervenes between the non-intermittent gear and intermittent gear, if there is interference between the tips of the teeth of the intermittent gear and the tips of the teeth of the drive gear, the intermittent gear and drive gear turn relative to each other, and mesh while avoiding collisions between the tips of their teeth.

In addition, when the intermittent gear turns in the second direction of rotation, the contact part of the intermittent gear contacts the contacted part of the intermittent cam gear, and the phase of the toothed part of the intermittent cam gear, and the phase of the toothed part of the intermittent gear, match.

In addition, because the intermittent gear causes the intermittent cam gear to also turn in the second direction of rotation when the contact part of the intermittent gear contacts the contacted part of the intermittent cam gear, the intermittent cam gear and drive gear mesh. Because the phase of the toothed part of the intermittent cam gear matches the phase of the toothed part of the intermittent gear already meshed with the drive gear, the teeth of the intermittent cam gear and the teeth of the drive gear do not collide when the intermittent cam gear meshes with the drive gear.

Another aspect of the invention is a printer comprising a printhead; and a cap unit that covers the ink nozzle face of the printhead, the cap unit having a moving mechanism that moves the cap between a capping position covering the ink nozzle face, and an open position removed from the ink nozzle face. The moving mechanism includes an intermittent cam gear having a cam channel in an end face; a drive gear able to mesh with the intermittent cam gear; and a cap holder including a holding member that holds the cap, a cam follower pin able to move inside the cam channel, a pin support mechanism that supports the cam follower pin movably in a direction perpendicular to the bottom of the cam channel, an urging member that urges the cam follower pin toward the bottom of the cam channel; and a slope that deepens in the direction in which the cam channel extends disposed to the bottom of the cam channel. The cam follower pin is positioned on the slope when meshing of the intermittent cam gear and drive gear is disengaged; and the intermittent cam gear turns and the intermittent part of the intermittent cam gear moves into opposition with the drive gear in conjunction with the cam follower pin sliding down the slope and moving toward the bottom of the cam channel due to the urging force of the urging member.

When a printer according to the invention goes to a standby mode, for example, the cap unit sets the cap to the capping position, and suppresses water evaporation from the printhead. The tips of the teeth of the intermittent cam gear can also escape from the tips of the teeth of the drive gear after meshing of the drive gear and intermittent cam gear of the moving mechanism that moves the cap disengage. In addition, rotation of the intermittent cam gear can be prevented or suppressed when, for example, an external shock is applied after the intermittent cam gear and drive gear disengage. Collision between the tips of the teeth of the intermittent gear and the drive gear can therefore be prevented or suppressed.

DESCRIPTION OF EMBODIMENTS

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

FIG. 1is a schematic section view illustrating the internal configuration of a printer using the invention. As shown inFIG. 1, the printer1has a rectangular, box-like case2. An entrance4for inserting recording paper3is disposed at the bottom of the front2aof the case2. A paper exit5from which the recording paper3is discharged is disposed in the top2bof the case2. The printer1is described below with reference to three mutually perpendicular axes, a longitudinal axis X between the front and back of the printer1, transverse axis Y, and vertical axis Z.

The side of the printer1where the entrance4is located is referred to as the front X1on the longitudinal axis X, and the opposite side on the longitudinal axis X is the back X2. The side of the printer1on one side on the transverse axis Y is referred to as the first side Y1, and the opposite side is referred to as the second side Y2. The first side Y1is the side seen when looking at the printer1as shown inFIG. 1(the left side when looking at the printer1from the front X1), and the opposite is the second side Y2(the right side when looking from the front X1).

Inside the case2of the printer1are a printhead7, and a paper conveyance path8going from the entrance4, past the printing position A of the printhead7, and to the paper exit5. The printhead7is an inkjet head. The printhead7is rectangular with the long side on the vertical axis Z, and the ink nozzle face7aof the printhead7facing the back X2. Multiple ink nozzles are aligned on the vertical axis Z on the ink nozzle face7a.

The paper conveyance path8includes a horizontal path9extending from the entrance4toward the back X2, a curved path10curving from the back end of the horizontal path9toward the back X2and up, and a vertical path11continuing up from the top end of the curved path10. The printing position A is on the vertical path11. The printhead7is disposed on the front X1side of the vertical path11.

The printer1also has, inside the case2, a conveyance mechanism13that conveys the recording paper3inserted to the entrance4through the paper conveyance path8, and a head moving mechanism14that moves the printhead7on the transverse axis Y.

The conveyance mechanism13includes a conveyance roller pair15, and a conveyance motor16that drives the conveyance roller pair15. The conveyance roller pair15is disposed to the curved path10. The conveyance roller pair15holds and conveys the recording paper3inserted to the paper conveyance path8through the entrance4.

The head moving mechanism14moves the printhead7between the printing position A on the vertical path11and a maintenance position removed from the printing position A to the second side Y2on the transverse axis Y. The head moving mechanism14scans the printhead7on the transverse axis Y at the printing position A.

The head moving mechanism14includes a carriage17; a pair of carriage guide rails18disposed one above the other along the transverse axis Y; and a carriage moving mechanism19that moves the carriage17along the carriage guide rails18. The carriage17is positioned between the upper and lower carriage guide rails18.

The carriage moving mechanism19includes a pair of pulleys20disposed to the opposite ends of the carriage guide rails18on the transverse axis Y; a timing belt21that goes around the pair of pulleys20; and a carriage motor22that drives the pair of pulleys20. The carriage17is connected to the timing belt21.

A cap unit25is disposed to the maintenance position. When the printhead7is at the maintenance position, the cap unit25caps the ink nozzle face7aof the printhead7with a cap26. The cap unit25includes a cap26, and a moving mechanism28that moves the cap26. The cap unit25has a drive motor27as the drive source of the moving mechanism28. The cap unit25is disposed at the back X2of the printhead7when the printhead7is at the maintenance position.

When print data is supplied from an external device and recording paper3is inserted to the entrance4, the printer1drives the conveyance motor16and conveys the recording paper3by means of the conveyance roller pair15through the paper conveyance path8. The printer1also drives the carriage motor22to move the printhead7from the maintenance position to the printing position A. The printer1then drives the carriage motor22and printhead7to print the print data on the recording paper3as it passes the printing position A while scanning the printhead7on the transverse axis Y at the printing position A.

When printing ends, the printer1drives the carriage motor22to move the printhead7from the printing position A to the maintenance position. When the printhead7reaches the maintenance position, the printer1drives the cap unit25(drive motor27) to cap the ink nozzle face7aof the printhead7with the cap26.

Cap Unit

FIG. 2is an oblique view of the cap26and moving mechanism28from the back X2on the first side Y1.FIG. 3is a plan view of the cap26and moving mechanism28from above. The cap unit25includes a cap26, drive motor27(seeFIG. 1), moving mechanism28, and base frame29. The base frame29extends on the longitudinal axis X and vertical axis Z, and supports the drive motor27and moving mechanism28. The moving mechanism28moves the cap26between a capping position26A covering the ink nozzle face7aof the printhead7, and an open position26B removed from the ink nozzle face7a. The capping position26A is closer to the front X1than the open position26B.

The cap26comprises a rectangular box31with the open side facing the front X1(the side where the printhead7is located); and a rectangular lip32attached to the open edge of the box31. The lip32is a plastic or other elastic body that is softer than the box31. The cap26can be manufactured by a two-shot plastic injection molding process, for example.

As shown inFIG. 2andFIG. 3, the moving mechanism28has a drive gear35to which rotation of the drive motor27is transferred, and an intermittent cam gear36that can mesh with the drive gear35.

The drive gear35and intermittent cam gear36are supported rotatably on support shafts37,38protruding toward the first side Y1from the base frame29. The support shaft37of the drive gear35is closer to the back X2than the support shaft38of the intermittent cam gear36. The drive gear35is a compound gear comprising a large diameter gear40, and a small diameter gear41having a smaller diameter than the large diameter gear40and is disposed coaxially to the large diameter gear40. Rotation of the drive motor27is transferred to the large diameter gear40through a pinion attached to the output shaft of the drive motor27, for example. The intermittent cam gear36can mesh with the small diameter gear41. Note that inFIG. 2andFIG. 3the teeth of the large diameter gear40and the teeth of the small diameter gear41are not shown.

As shown inFIG. 2, the intermittent cam gear36has a cam channel43in the end face on the first side Y1on the transverse axis Y. The intermittent cam gear36also has an open part44that communicates with the transverse axis Y (the axial direction of the support shaft37) at a position offset radially from the support shaft37. The open part44is formed in an arc defined around the center of the support shaft37. The cam channel43is described in detail below.

The moving mechanism28also has a cap holder45that holds the cap26, and a support mechanism46that supports the cap holder45movably on the longitudinal axis X (radially to the intermittent cam gear36).

The cap holder45includes a holding member48that holds the cap26; a cam follower pin49that can move inside the cam channel43of the intermittent cam gear36; a pin support mechanism50that can move the cam follower pin49in a direction intersecting (in this example, a direction perpendicular to) the bottom43aof the cam channel43; and a coil spring51(urging member) that urges the cam follower pin49in the direction toward the bottom43aof the cam channel43(toward the second side Y2).

The holding member48is disposed to the front end part of the cap holder45. The pin support mechanism50is disposed at the back end part of the cap holder45. The back end part of the cap holder45is positioned superimposed with the intermittent cam gear36when looking at the cap unit25from the transverse axis Y. The cam follower pin49extends on the transverse axis Y. The pin support mechanism50supports the cam follower pin49movably on the transverse axis Y, and causes the distal end of the cam follower pin49to project toward the intermittent cam gear36side (the second side Y2). The coil spring51urges the cam follower pin49to the intermittent cam gear36side (the second side Y2). The distal end of the cam follower pin49is inserted to the cam channel43of the intermittent cam gear36. The cam follower pin49is pushed by the coil spring51to the bottom43aof the cam channel43.

The cam channel43of the intermittent cam gear36is formed in a spiral. More specifically, the cam channel43has an inside wall53spiraling from a position near the center of the intermittent cam gear36to the outside circumference side, and an outside wall54spiraling along the outside side of the inside wall53. The bottom43aconnects the back X2edge of the inside wall53with the back X2edge of the outside wall54.

FIG. 4is a side view from the front X1side of the cap26and moving mechanism28when the cap26is at the open position26B.

FIG. 5is a section view through line S-S′ inFIG. 4. The cap26is at the open position26B inFIG. 4andFIG. 5.

FIG. 6is a side view from the front X1side of the cap26and moving mechanism28when the cap26is at the capping position26A.

Note that the base frame29is omitted inFIG. 4andFIG. 6. Also, inFIG. 4andFIG. 6, so that the relative positions of the intermittent cam gear36and cap holder45to each other can be understood, the parts of the intermittent cam gear36that is hidden by the cap holder45when seen from the front X1are indicated by solid lines in the same way as the parts that are not hidden.

As shown inFIG. 4andFIG. 5, a slope57that becomes deeper in the direction the cam channel43extends is formed on the bottom43aof the inside circumference end56of the cam channel43. The slope57descends toward the inside circumference end of the cam channel43. An end wall59(wall) facing the slope57is disposed at the end of the end56portion of the cam channel43where the slope57is disposed. The end wall59defines the end of the inside circumference side of the cam channel43. As shown inFIG. 4, the end61of cam channel43on the outside circumference side is a curved part62that curves to the inside circumference side. In other words, at the outside circumference end61of the cam channel43, the inside wall53and the outside wall54of the cam channel43extend straight to the inside circumference side.

When the toothed part63of the intermittent cam gear36meshes with the drive gear35and turns, the cam follower pin49slides through the cam channel between the end56on the inside circumference side and the end61on the outside circumference side of the cam channel43. When the cam follower pin49is at the inside circumference end of the cam channel43, the cap26held by the cap holder45is positioned to the open position26B (seeFIG. 4). When the cam follower pin49moves to the outside circumference end of the cam channel43, the cap26held by the cap holder45is positioned to the capping position26A (seeFIG. 6).

As shown inFIG. 2,FIG. 3, andFIG. 5, the moving mechanism28includes an intermittent gear65disposed coaxially to the intermittent cam gear36; a non-intermittent gear66with teeth around the entire circumference disposed coaxially on the opposite side of the intermittent gear65as the intermittent cam gear36; and a friction clutch67configured between the intermittent gear65and non-intermittent gear66. The intermittent gear65and non-intermittent gear66are supported rotatably on the support shaft38. The intermittent gear65can mesh with the drive gear35, and the non-intermittent gear66meshes with the drive gear35.

The intermittent gear65has a toothed part of the same diameter and same module as the intermittent cam gear36. The number of teeth in the toothed part64of the intermittent gear65is greater than the number of teeth in the toothed part63of the intermittent cam gear36. As shown inFIG. 2, the area of the intermittent part68where teeth are not formed on the intermittent gear65is therefore smaller than the area of the intermittent part69of the intermittent cam gear36.

When seen on the transverse axis Y (in line with the axis of rotation), the intermittent gear65and intermittent cam gear36are disposed to angular positions where the intermittent part69of the intermittent cam gear36and the intermittent part68of the intermittent gear65overlap. The intermittent gear65and intermittent cam gear36can also rotate relative to each other.

As shown inFIG. 5, the intermittent gear65has, on the intermittent cam gear36side face at a position separated radially from the axis of rotation, a protrusion70(contact part) that protrudes to the intermittent cam gear36side. The protrusion70is inserted to the open part44of the intermittent cam gear36. When the intermittent gear65and intermittent cam gear36turn relative to each other, the protrusion70can move circumferentially inside the open part44.

The toothed part of the non-intermittent gear66has the same diameter and same module as the intermittent cam gear36.

As shown inFIG. 5, the friction clutch67has a round contact surface72disposed in the face of the non-intermittent gear66on the intermittent gear65side, and an annular contacted part73disposed to a position on the intermittent gear65that contacts the contact surface72. As shown inFIG. 3, the non-intermittent gear66is urged, by an urging spring74disposed between the base frame29and non-intermittent gear66, from the opposite side as the intermittent gear65, to the intermittent gear65. Rotation of the non-intermittent gear66is therefore transferred through the friction clutch67to the intermittent gear65. As a result, when the non-intermittent gear66turns, the intermittent gear65turns in unison with the non-intermittent gear66. When a load is applied to the intermittent gear65, such as from interference between the tip of the teeth of the drive gear35and the tip of the teeth of the intermittent gear65, the intermittent gear65turns relative to the non-intermittent gear66and the load is relieved.

Movement of the Cap by the Cap Unit

Movement of the cap26by the cap unit25is described next with reference toFIG. 4toFIG. 7.FIG. 7is a side view from the first side Y1of the state just after meshing of the drive gear35and intermittent cam gear36disengages.

When the drive gear35and intermittent cam gear36are meshed, the drive gear35is driven, and the intermittent cam gear36turns in first direction of rotation R1, the cam follower pin49slides in the cam channel43and moves to the inside circumference side (back X2) of the intermittent cam gear36. As a result, the cap holder45moves to the back X2, and the cap26held by the cap holder45moves to the back X2(the opening direction from the capping position26A to the open position26B).

As shown inFIG. 4, when the cam follower pin49then reaches the end56on the inside circumference side of the cam channel43, the cap26reaches the open position26B. When the cam follower pin49reaches the end56on the inside circumference side of the cam channel43, the drive gear35and intermittent cam gear36disengage. More specifically, the tooth36aat the end of the toothed part63of the intermittent cam gear36in the first direction of rotation R1disengages the drive gear35.

When the intermittent cam gear36stops turning when the drive gear35and intermittent cam gear36have disengaged, the tip of the tooth65athat last engaged the drive gear35, and the tip of a tooth of the drive gear35, may collide the next time the gears start to mesh. The next time the gears start to mesh is when the drive gear35turns in the opposite direction of rotation as the direction of rotation before the gears disengaged, and begins to engage the tooth65aof the intermittent cam gear36. In other words, the gears begin to mesh when the drive gear35begins to engage the tooth65aof the intermittent cam gear36when the cap26is moved from the open position26B to the capping position26A.

To solve this problem, in this example, as shown inFIG. 7, the cam follower pin49is positioned on the slope57of the cam channel43when the intermittent cam gear36and drive gear35are disengaged. Therefore, the cam follower pin49moves, by the urging force of the coil spring51, in the direction toward the bottom43a(second side Y2) while sliding down the slope57. Because the slope57is inclined and goes deeper towards the back of the first direction of rotation R1, when the cam follower pin49moves while sliding down the slope57, the intermittent cam gear36is pushed by the cam follower pin49and turns in the first direction of rotation R1. As a result, as shown inFIG. 4, the drive gear35and the intermittent part69of the intermittent cam gear36, are in opposition. More specifically, the tip of the teeth36aof the intermittent cam gear36separates from (disengages) the teeth of the drive gear35. Collision between the tips of the teeth36aof the intermittent cam gear36, and the tips of the teeth of the drive gear35, when the gears next start to mesh can therefore be prevented or suppressed.

The cam follower pin49that slid down the slope57then meets the end wall59of the cam channel43. When the cam follower pin49contacts the end wall59, rotation of the intermittent cam gear36stops. Contact between the cam follower pin49and end wall59therefore limits rotation of the intermittent cam gear36in the first direction of rotation R1after the intermittent cam gear36and drive gear35have disengaged.

When the cap26is then moved from the open position26B to the capping position26A, the drive gear35is driven in the opposite direction as the direction described above from the position shown inFIG. 4, thereby turning the non-intermittent gear66in the second direction of rotation R2, which is opposite the first direction of rotation R1. When the non-intermittent gear66turns in the second direction of rotation R2, the non-intermittent gear66rotation is transferred through the friction clutch67to the intermittent gear65. The intermittent gear65therefore turns in the second direction of rotation R2. Because the intermittent part68of the intermittent gear65is shorter than the intermittent part69of the intermittent cam gear36, the intermittent gear65turning in the second direction of rotation R2meshes with the drive gear35before the intermittent cam gear36.

The intermittent gear65and drive gear35mesh without teeth thereof colliding. More specifically, because the friction clutch67intervenes between the non-intermittent gear66and intermittent gear65, when the tip of a tooth of the intermittent gear65and the tip of a tooth of the drive gear35meet and load is applied to the intermittent gear65, the intermittent gear65rotates in relation to the non-intermittent gear66and relieves the load. As a result, the intermittent gear65and drive gear35can mesh while avoiding collisions between their teeth.

When the intermittent gear65meshed with the drive gear35then turns in the second direction of rotation R2, the protrusion70(contact part) of the intermittent gear65contacts the inside wall of the open part44of the intermittent cam gear36from the back X2in the second direction of rotation R2. More specifically, the protrusion70of the intermittent gear65contacts the inside wall part81defining the front end of the open part44of the intermittent cam gear36in the second direction of rotation R2.

When the protrusion70of the intermittent gear65contacts the inside wall part81of the open part44of the intermittent cam gear36, the phase of the toothed part63of the intermittent cam gear36, and the phase of the toothed part64of the intermittent gear65already meshed with the drive gear35, match. In addition, when the protrusion70of the intermittent gear65is in contact with the inside wall part81of the open part44of the intermittent cam gear36, and the intermittent gear65meshed with the drive gear35turns in the second direction of rotation R2, the intermittent gear65causes the intermittent cam gear36to also turn in the second direction of rotation R2. The intermittent cam gear36therefore meshes with the drive gear35. The phase of the toothed part63of the intermittent cam gear36, and the phase of the toothed part64of the intermittent gear65already meshed with the drive gear35, match. Therefore, when the intermittent cam gear36meshes with the drive gear35, the tip of the tooth36aof the intermittent cam gear36, and the tips of the teeth of the drive gear35, do not collide.

When the intermittent cam gear36then turns in the second direction of rotation R2due to engagement with the drive gear35, the cam follower pin49slides along the cam channel43and moves to the outside circumference side (front X1) of the intermittent cam gear36. As a result, the cap holder45moves to the front X1, and the cap26held by the cap holder45moves to the front X1(the direction from the open position26B to the capping position26A).

As shown inFIG. 6, when the cam follower pin49reaches the outside circumference end61of the cam channel43, the cap26is set to the capping position26A. When the cam follower pin49reaches the outside circumference end61of the cam channel43, meshing of the drive gear35and intermittent cam gear36is also disengaged.

When the intermittent cam gear36stops turning when the drive gear35and intermittent cam gear36have disengaged, the tip of the tooth65bthat last engaged the drive gear35, and the tip of a tooth of the drive gear35, may collide the next time the gears start to mesh. The next time the gears start to mesh is when the drive gear35turns in the opposite direction of rotation as the direction of rotation before the gears disengaged, and begins to engage the tooth65bof the intermittent cam gear36. In other words, the gears begin to mesh when the drive gear35begins to engage the tooth65bof the intermittent cam gear36when the cap26is moved from the capping position26A to the open position26B.

In contrast, when meshing of the drive gear35and intermittent cam gear36disengage, the cam follower pin49is in the curved part62(end61) of the cam channel43. Because the lip32of the cap26is pressed against the ink nozzle face7aof the printhead7in the capping position26A, the elastic restoring force of the lip32causes the cam follower pin49to slide along the inside wall53of the curved part62and move to the inside circumference side of the intermittent cam gear36. Because the inside wall53of the curved part62slopes to the inside circumference side toward the back of the second direction of rotation R2, when the cam follower pin49slides along the inside wall53of the curved part62and moves to the inside circumference side of the intermittent cam gear36, the intermittent cam gear36is pushed by the cam follower pin49and moves in the second direction of rotation R2. As a result, as shown inFIG. 6, the tip of the tooth36bof the intermittent cam gear36separates from (disengages) the teeth of the drive gear35, and the drive gear35and the intermittent part69of the intermittent cam gear36go in opposition. The tip of the tooth36bof the intermittent cam gear36, and the tip of the teeth of the drive gear35, colliding when the gears start to mesh next time can therefore be prevented or suppressed.

When then moving the cap26from the capping position26A to the open position26B, the drive gear35again turns in the opposite direction, and the non-intermittent gear66turns in the first direction of rotation R1. When the non-intermittent gear66turns in the first direction of rotation R1, the rotation is transferred through the friction clutch67to the intermittent gear65. The intermittent gear65therefore turns in the second direction of rotation R1. Because the intermittent part68of the intermittent gear65is shorter than the intermittent part69of the intermittent cam gear36, the intermittent gear65turning in the second direction of rotation R1meshes with the drive gear35before the intermittent cam gear36. The intermittent gear65therefore turns in the first direction of rotation R1. Because the intermittent part68of the intermittent gear65is shorter than the intermittent part69of the intermittent cam gear36, the intermittent gear65turning in the first direction of rotation R1meshes with the drive gear35before the intermittent cam gear36. Because the friction clutch67intervenes between the non-intermittent gear66and intermittent gear65, the intermittent gear65and drive gear35mesh without their teeth colliding.

When the intermittent gear65meshed with the drive gear35then turns in the first direction of rotation R1, the protrusion70of the intermittent gear65contacts the inside wall of the open part44of the intermittent cam gear36from the back X2in the first direction of rotation R1. More specifically, the protrusion70of the intermittent gear65contacts the inside wall part82defining the front end of the open part44of the intermittent cam gear36in the first direction of rotation R1. As a result, the phase of the toothed part63of the intermittent cam gear36, and the phase of the toothed part64of the intermittent gear65already meshed with the drive gear35, match. In addition, when the protrusion70of the intermittent gear65is in contact with the inside wall part82of the open part44of the intermittent cam gear36, and the intermittent gear65turns further, the intermittent gear65causes the intermittent cam gear36to also turn in the first direction of rotation R1. The intermittent cam gear36therefore meshes with the drive gear35. The phase of the toothed part63of the intermittent cam gear36, and the phase of the toothed part64of the intermittent gear65already meshed with the drive gear35, match. Therefore, when the intermittent cam gear36meshes with the drive gear35, the tip of the tooth36aof the intermittent cam gear36, and the tips of the teeth of the drive gear35, do not collide.

When the intermittent cam gear36then turns further in the first direction of rotation R1due to engagement with the drive gear35, the cam follower pin49slides along the cam channel43and moves to the inside circumference side (front X1) of the intermittent cam gear36. As a result, the cap holder45moves to the back X2, and the cap26held by the cap holder45moves to the back X2(the direction from the capping position26A to the open position26B).

When the cam follower pin49then reaches the inside circumference end61of the cam channel43, the cap26is set to the open position26B. When the cam follower pin49reaches the inside circumference end56of the cam channel43, meshing of the drive gear35and intermittent cam gear36is also disengaged.

If the intermittent gear65turns due to an external disturbance such as a physical shock after the intermittent gear65and drive gear35disengage, the tip of a tooth of the intermittent gear65and the tip of a tooth of the drive gear35colliding when the gears begin to mesh next increases.

To solve this, the cam follower pin49of the cap holder45in this example is pushed by the urging force of the coil spring51to the intermittent cam gear36. Rotation of the intermittent cam gear36can therefore be prevented or suppressed even when an external impact is applied after the intermittent cam gear36and drive gear35disengage. As a result, collision between the tips of teeth in the intermittent gear65and the tips of teeth in the drive gear35when the gears next mesh can be prevented.

OTHER EXAMPLES

A slope57is provided on the inside circumference end56of the cam channel43in the embodiment described above, but a slope that goes deeper toward the outside circumference end may be provided on the outside circumference end61of the cam channel43.

In this configuration, when the cap26moves to the capping position26A, and the drive gear35and intermittent cam gear36disengage, the cam follower pin49is positioned on the slope of the outside circumference end61of the cam channel43. Therefore, the urging force of the coil spring51causes the cam follower pin49to slide along the slope in the direction toward the bottom43a(second side Y2).

Because the slope is inclined in the direction becoming deeper towards the back of the second direction of rotation R2, when the cam follower pin49moves sliding along the slope57, the intermittent cam gear36is pushed by the cam follower pin49and turns in the second direction of rotation R2.

As a result, the tip of the tooth36bof the intermittent cam gear36separates from (disengages) the drive gear35, and the drive gear35and intermittent part69of the intermittent cam gear36are in opposition. Collisions between the tip of the tooth36bof the intermittent cam gear36and the tips of the teeth of the drive gear35when the gears next begin to mesh can be prevented or suppressed. Note that when a slope57is provided on the outside circumference end61of the cam channel43, there is no need to provide the curved part62at the outside circumference end61of the cam channel43.

The entire disclosure of Japanese Patent Application No: 2016-081824, filed Apr. 15, 2016 is expressly incorporated by reference herein in its entirety.