JP5115036B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an ink jet printer that discharges air (bubbles) in a sub tank to the main tank side by circulating ink between the main tank and the sub tank.

When the air (bubbles) in the sub tank is supplied to the recording head, ink ejection failure occurs.
Therefore, for example, in the invention described in Patent Document 1, when the main tank and the sub tank are connected by a tube, and ink is supplemented to the sub tank, the ink in the main tank is supplied to the sub tank via the tube, and the sub tank In order to remove the air inside, the air in the sub tank is returned to the main tank through the tube used for ink supply together with the ink.
JP 2002-166570 A

  However, in the invention described in Patent Document 1, the tube for supplying ink from the main tank to the sub tank also serves as a tube for returning ink from the sub tank to the main tank. Therefore, in order to remove the air in the sub tank, the sub tank When returning ink from the main tank to the main tank, if air remains in the tube, when the ink is supplied from the main tank to the sub tank, the remaining air returns to the sub tank and sufficiently removes the air in the sub tank. I can't.

  This can be solved by making the amount of ink returned from the sub tank to the main tank larger than at least the volume of the tube from the sub tank to the main tank. Since the amount of ink to be returned has to be large, there is a problem that the efficiency of removing air with respect to the amount of ink returned to the sub tank is low.

  An object of this invention is to remove the air in a sub tank efficiently in view of the said point.

In order to achieve the above object, according to the present invention, in the first aspect of the present invention, a main tank that is fixed to the apparatus main body and stores ink, a recording head that ejects ink toward a recording medium, And a sub-tank that supplies ink to the recording head, reciprocates in a predetermined scanning direction, a sub-tank side channel port connected to the sub-tank side, and a first main tank side stream connected to the main tank side A passage opening and a second main tank side passage opening, and only the ink flow from the first main tank side passage opening to the sub tank side passage opening and the ink circulation from the sub tank passage opening to the second main tank side passage opening. And an allowed flow path branching unit.
Then, the pressing lever is operated by a pressing mechanism that operates by obtaining a driving force from a discharge roller for transporting the recording medium to the discharge port side, and the ink is circulated through the ink flow path by the pump action due to the volume deformation of the sub tank. It is also characterized by making it.

  Thus, in the first aspect of the invention, the amount of ink when returning ink from the sub tank to the main tank to remove air in the sub tank is at least as large as the volume of the ink flow path from the sub tank to the flow path branching unit. Increasing it is enough.

  That is, the ink returning from the sub tank to the main tank flows from the sub tank channel port to the second main tank side channel port side in the channel branching unit. On the other hand, when ink is supplied from the main tank to the sub tank, the ink flows from the first main tank side channel port to the sub tank side channel port.

  That is, in the first aspect of the invention, between the flow path branching unit and the main tank, the flow path of the ink flowing from the flow path branching unit to the main tank, and from the main tank to the flow path branching unit. The flow path of the flowing ink becomes independent.

  For this reason, when the ink in the sub tank is returned to the main tank side in order to remove the air in the sub tank, the ink flow path from the flow path branching unit (second main tank side flow path port) to the main tank is temporarily assumed. Even when air remains, the possibility that the remaining air flows into the ink flow path flowing from the main tank toward the flow path branching unit (first main tank side flow path port) is extremely low.

Therefore, the amount of ink returned from the sub tank to the main tank is reduced as compared with the invention described in Patent Document 1 in which the volume of the ink flow path from at least the sub tank to the main tank must be made larger. Therefore, the air in the sub tank can be efficiently removed.
In the invention according to claim 2, a transmittable state in which the driving force can be transmitted from the paper discharge roller to the pressing mechanism, and a non-transmittable state in which the driving force cannot be transmitted from the discharge roller to the pressing mechanism. The pressing mechanism is disposed at a position deviated from the conveyance path through which the recording medium is conveyed, and the head unit is positioned at a position deviated from the conveyance path when in a transmittable state. It is characterized by.
According to a third aspect of the present invention, the pressing mechanism is provided on the same shaft as the paper discharge roller, and is engaged with the gear rotating with the paper discharge roller, and the position where the transmission is possible and the state where transmission is impossible. The actuator has a pinion gear that is movable between the position and the actuator, and the actuator moves the pinion gear to switch the transmission state of the driving force.

  By the way, the inventor separately provides a tube constituting an ink flow path for supplying ink from the main tank to the sub tank and a tube constituting an ink flow path for returning ink from the sub tank to the main tank. Thus, an ink jet printer that uniquely prevents the air remaining in the tube when returning the ink to the main tank from flowing into the tube supplying the ink from the main tank to the sub tank is uniquely considered.

  However, in this solution, the sub tank and the main tank are connected by at least two tubes, and when the head unit reciprocates, these two tubes bend with the reciprocation of the head unit. Therefore, when the head unit is reciprocated, a large resistance force is generated, and it is difficult to smoothly reciprocate the head unit.

  On the other hand, in the invention described in claim 2, the ink flow path from the main tank to the sub tank has a movable area that is displaced along with the reciprocating movement of the head unit, and a fixed area that is fixed to the apparatus main body. Further, the flow path branching unit is characterized in that it is provided in a fixed area in the middle of the ink flow path.

Accordingly, in the invention described in claim 4 , the sub tank and the flow path branching unit are connected by a single ink flow path at least in the movable region of the ink flow path from the main tank to the sub tank. Therefore, it is possible to suppress an increase in resistance force when the head unit is reciprocated. Therefore, since the head unit can be smoothly reciprocated, the print quality can be improved.

In the invention according to claim 5 , since the sub tank is configured so that the air in the sub tank is discharged to the ink flow path preferentially over the ink, without increasing the amount of ink returned to the main tank. The air in the sub tank can be reliably removed.

  By the way, if the rigidity of the members constituting the ink flow path is lowered to improve the flexibility, the gas permeability increases, so that the water in the ink staying in the ink flow path evaporates and the inside of the ink flow path is increased. The viscosity of the ink increases and the fluidity of the ink deteriorates.

On the other hand, if the gas permeability of the member constituting the ink flow path is reduced, the rigidity is increased and the flexibility is deteriorated, so that the resistance force when the head unit is reciprocated is increased.
Therefore, in the invention described in claim 6 , the gas permeability of the member constituting the ink flow path from the flow path branch unit to the main tank is the gas permeability of the member constituting the ink flow path from the flow path branch unit to the sub tank. It is characterized by being smaller than the transmittance.

Thus, according to the sixth aspect of the present invention, moisture in the ink staying in the ink flow path is obtained while ensuring flexibility and suppressing an increase in resistance force when the head unit is reciprocated. Can be prevented from evaporating.

Hereinafter, an inkjet printer according to an embodiment of the present invention will be described with reference to the drawings.
1. DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an image forming unit of an ink jet printer according to this embodiment as viewed from above, FIG. 2 is a cross-sectional view showing the structure of ink flow paths 141 and 142, and FIG. It is a figure which shows the state of the press mechanism 160 in the normal time, and FIG. 4 is a figure which shows the operation state at the time of removing the air in the subtank 121. FIG.

2. As is well known, an inkjet printer forms an image on a sheet by ejecting minute ink droplets toward a recording medium such as a recording sheet (hereinafter referred to as a sheet). In the case of forming a color image, images of various colors are formed by superimposing basic colors such as cyan, magenta, yellow, and photo black.

  The ink jet printer according to the present embodiment connects a sub tank 121 described later and a main tank unit 130 described below with a tube or the like, so that a tube that continuously supplies ink from the main tank unit 130 to the sub tank 121 is provided. This is a supply type printer.

2. Recording Head Unit In FIG. 1, a recording head unit (carriage) 100 includes a recording head 110 that ejects ink droplets onto a sheet, a sub tank unit 120 that supplies ink to the recording head 110, and the like. The recording head unit 100 scans in the main scanning direction, which is a predetermined scanning direction (ie, a horizontal direction in FIG. 1) that is perpendicular to the paper transport direction and parallel to the paper recording surface during image formation. Reciprocating).

  Note that a plurality of nozzles (not shown) for ejecting ink of each color are provided on the surface of the recording head 110 that faces the conveyed paper, and these nozzles are The colors are arranged in a line in a direction parallel to the paper conveyance direction.

  The sub tank unit 120 includes sub tanks 121C, 121M, 121Y, 121PBk filled with cyan (C), magenta (M), yellow (Y), and black (Bk) inks, and sub tanks 121C, 121M, 121Y, It has pressure levers 122C, 122M, 122Y, 122Bk and the like for pressing 121Bk. Incidentally, these sub tanks 121C, 121M, 121Y, 121Bk are arranged in series in the main scanning direction.

  The sub tanks 121C, 121M, 121Y, and 121Bk are the same except that the filled inks are different, and the others are the same. Therefore, these sub tanks are hereinafter collectively referred to as the sub tank 121. Further, since the pressing levers 122C, 122M, 122Y, and 122Bk are different only in the sub-tank 121 to be pressed, hereinafter, these pressing levers are collectively referred to as a pressing lever 122.

  Further, the sub-tank 121 is configured to be elastically (expandable) deformable in a direction (vertical direction in the present embodiment) orthogonal to the paper transport direction and the main scanning direction. Specifically, FIG. 2 and FIG. As shown in FIG. Incidentally, the sub-tank 121 according to the present embodiment is configured by a bellows whose cross-sectional shape orthogonal to the expansion / contraction direction is a substantially rectangular shape.

  As shown in FIG. 3, the sub tank 121 is provided with a first flow path port 121A communicating with the recording head 110 side and a second flow path port 121B communicating with the main tank unit 130 side. The first flow path port 121A communicates with the lower space of the sub tank 121, and the second flow path port 121B communicates with the upper space within the sub tank 121.

  The pressing lever 122 is a lever member whose one end side 122 </ b> A is rotatably connected to the upper end portion of the sub tank 121, and whose other end 122 </ b> B extends outward from the outer edge portion of the recording head unit 100. Between the one end side 122A and the other end side 122B, there is provided a support portion 122C that is fixed to the main body portion of the recording head unit 100 and supports the pressing lever 122 in a swingable manner.

  The pressing lever 122 presses the sub tank 121 so that the other end side is pressed from the lower side to the upper side by a pressing mechanism 160 described later, and the sub tank 121 is contracted and deformed.

2. Main tank unit As shown in FIG. 1, the main tank unit 130 has a plurality of ink cartridges (main tanks) 131 filled with ink for replenishing and supplying each sub tank 121, and these ink cartridges 131 are attached and detached. The main tank unit 130 is fixed to the apparatus main body. The cartridge casing (not shown) and the like are assembled as possible.

In the present embodiment, the apparatus main body refers to a non-movable part of the inkjet printer such as a frame or a casing of the inkjet printer.
Further, the ink flow path 140 from each ink cartridge 131 to the corresponding sub tank 121 includes a movable area 140A that is displaced along with the reciprocating movement of the recording head unit 100, and a fixed area 140B that is fixed to the apparatus main body. Has been.

  A flow path branch unit 150 is provided in the fixed area 140 </ b> B of the ink flow path 140 and connected to the movable area 140 </ b> A and the fixed area 140 </ b> B. The main tank unit 130 is provided from the flow path branch unit 150. The ink flow path 140 on the side is branched into two types of ink flow paths 141 and 142 by the flow path branching unit 150, while the sub tank 121 side (the movable range 140A in this embodiment) from the flow path branching unit 150 is Two types of ink flow paths 141 and 142 are gathered to form one type of ink flow path 143.

  In FIG. 1, for the sake of space, one ink channel 143 in the movable area 140A, one channel branch unit 150, and an ink channel 141 from the channel branch unit 150 to the main tank unit 130, Although two 142 are described, in practice, a flow branch unit 150 is provided in each ink flow path 140 of each color (each sub tank 121).

  The ink flow path 141 is an ink flow path 140 for supplying ink from the main tank unit 130 to the sub tank 121, and the ink flow path 142 is from the flow path branching unit 150 (sub tank 121) side to the main tank unit 130. This is an ink flow path 140 for the ink returning to FIG.

  Further, the housing (not shown) of the flow path branch unit 150 includes a sub tank side flow path port 151 connected to the sub tank 121 side, a first main tank side flow path port 152 connected to the main tank unit 130 side, and A second main tank side channel port 153 is provided.

  In the housing of the flow path branching unit 150, the ink flow from the first main tank side flow path port 152 to the sub tank side flow path port 151 is allowed, and the first main tank side flow path from the sub tank side flow path port 151 is allowed. A first check valve 154 that blocks the flow of ink to the path port 152 and a second main tank side channel port that allow the ink to flow from the sub-tank side channel port 151 to the second main tank side channel port 153. A second check valve 155 is provided to prevent the ink from flowing from 153 to the sub-tank side channel port 151.

  In addition, the ink flow path 143 extending from the sub tank 121 to the flow path branching unit 150 is a movable area 140A, and is configured by a flexible tube such as polypropylene (PP) or polyethylene (PE). Since the ink flow paths 141 and 142 from the flow path branching unit 150 to the main tank unit 130 are the fixed areas 140B, there is no need to configure them with flexible tubes.

  Therefore, in this embodiment, as shown in FIG. 2, the ink channel is formed by closing the opening side (upper side in FIG. 2) of the groove portion 144 </ b> A of the plate 144 on which the groove portion 144 </ b> A is formed with a lid member 145. 141 and 142, and the plate 144 and the lid member 145 are made of a material such as an aluminum vapor deposition film. As a result, the plate 144 and the lid member 145 have gas (air) permeability lower than that of polypropylene (PP) or polyethylene (PE).

  Therefore, in this embodiment, the gas permeability in the ink flow paths 141 and 142 from the flow path branch unit 150 to the main tank unit 130 is the same as that in the ink flow path 143 from the flow path branch unit 150 to the sub tank 121. It is getting smaller.

  In this embodiment, since the main tank unit 130 is set so that the ink height in the main tank unit 130 is lower than the ink height in the sub tank 121, the pressure in the recording head 110 is caused by the water head difference. It becomes lower than atmospheric pressure and the meniscus of the nozzle is maintained.

  When ink is ejected from the recording head 110 and the pressure in the sub tank 121 decreases, the ink in the main tank unit 130 moves to the sub tank 121 to compensate for the reduced pressure, and the ink is supplied to the sub tank 121. .

3. As shown in FIG. 3, the slide cam 161 of the pressing mechanism 160 is in contact with the longitudinal end of the push rod 162 that presses the other end side 122B of the pressing lever 122 from the lower side to the upper side. A cam surface 163 for displacing 162 in the longitudinal direction (vertical direction in the present embodiment) is formed.

  In this embodiment, when the push rod 162 is moved upward, the slide cam 161 is shown in FIG. 3 in a direction perpendicular to the longitudinal direction of the push rod 162 (in the sub scanning direction in this embodiment). The state is moved to the state shown in FIG. In this embodiment, the driving force for operating the slide cam 161 is applied from a paper discharge roller 170 (see FIG. 1) described later.

  On the other hand, when the push rod 162 is moved downward, the driving force from the paper discharge roller 170 is cut off, and the slide cam 161 is orthogonal to the longitudinal direction of the push rod 162 by the elastic force of the return spring 164. In the direction (sub-scanning direction in this embodiment), the state is moved from the state shown in FIG. 4 to the state shown in FIG.

  A plurality of slide cams 161 provided for each sub-tank 121 are integrated by a base plate 165. As shown in FIG. 1, a rack gear is provided on the base plate 165 on the discharge roller 170 side. 165A is provided.

  Then, the pinion gear 166 that transmits the driving force from the gear 170A provided at the longitudinal end portion of the paper discharge roller 170 to the rack gear 165A (base plate 165) is shifted from the position where the rack gear 165A meshes with the rack gear 165A and meshes with the rack gear 165A. The pinion gear 166 is switched in position by an actuator such as an electromagnetic solenoid (not shown).

  The paper discharge roller 170 is a transport means for transporting the paper on which image formation has been completed to a discharge port (not shown), and the paper is transported between a pair of left and right frames 171 and discharged. .

4). Features of the Inkjet Printer According to the Present Embodiment When the air (bubbles) in the sub tank 121 is supplied to the recording head 110, an ink ejection failure occurs.

  Therefore, in the present embodiment, the ink channel 143, the second check valve 155, and the ink channel are operated by operating the pressing mechanism 160 to reduce and deform the sub tank 121 periodically or based on a command from the user. The air in the sub tank 121 is returned to the main tank unit 130 (ink cartridge 131) side together with the ink via the 142.

  Then, when the pressing force to the sub tank 121 is released when the discharge of air is finished, the sub tank 121 expands due to the restoring force (elastic force) of the sub tank 121 itself, and the ink on the main tank unit 130 side is transferred to the ink flow path 141. Then, the air is sucked into the sub tank 121 through the first check valve 154 and the ink flow path 143.

  At this time, if the tube for supplying ink from the main tank unit 130 to the sub tank 121 serves as a tube for returning ink from the sub tank 121 to the main tank unit 130 as in the invention described in Patent Document 1, When the ink is returned from the sub tank 121 to the main tank unit 130 in order to remove the air in the sub tank 121, if air remains in the tube, the ink remains when the ink is supplied from the main tank unit 130 to the sub tank 121. The air returns to the sub tank 121, and the air in the sub tank 121 cannot be removed sufficiently.

  This can be solved if the amount of ink returned from the sub tank 121 to the main tank unit 130 is at least larger than the volume of the tube from the sub tank 121 to the main tank unit 130. Since the amount of ink returned from the sub tank 121 to the main tank unit 130 must be large, there is a problem that the efficiency of removing air with respect to the amount of ink returned to the sub tank 121 is low.

  In this embodiment, only the circulation of ink from the first main tank side flow path port 152 to the sub tank side flow path port 151 and the flow of ink from the sub tank 121 flow path port to the second main tank side flow path port 153 are allowed. Since the flow path branch unit 150 is provided, the amount of ink when returning ink from the sub tank 121 to the main tank unit 130 in order to remove the air in the sub tank 121 is at least the ink from the sub tank 121 to the flow path branch unit 150. It is sufficient to make it larger than the volume of the flow path.

  That is, the ink returning from the sub tank 121 to the main tank unit 130 flows from the sub tank 121 flow path port to the second main tank side flow path port 153 side in the flow path branching unit 150. On the other hand, when ink is supplied from the main tank unit 130 to the sub tank 121, the ink flows from the first main tank side channel port 152 to the sub tank side channel port 151.

  That is, in this embodiment, between the flow path branch unit 150 and the main tank unit 130, the flow path of the ink flowing from the flow path branch unit 150 toward the main tank unit 130, and the flow path branch from the main tank unit 130. The flow path of the ink flowing toward the unit 150 becomes independent.

  Therefore, when the ink in the sub tank 121 is returned to the main tank unit 130 side in order to remove the air in the sub tank 121, the main tank is temporarily connected to the main tank unit 130 (second main tank side flow path port 153). Even when air remains in the ink flow path leading to the unit 130, the remaining air flows from the main tank unit 130 toward the flow path branching unit 150 (first main tank side flow path port 152). The possibility of flowing into the flow path is extremely low.

  Therefore, the amount of ink returned from the sub tank 121 to the main tank unit 130 is at least larger than the volume of the ink flow path from the sub tank 121 to the main tank unit 130, as compared with the invention described in Patent Document 1. Since the amount of ink returned to can be reduced, the air in the sub tank 121 can be efficiently removed.

  By the way, with respect to the problem that the air in the sub-tank 121 cannot be sufficiently removed, the inventor has developed a tube constituting an ink flow path for supplying ink from the main tank unit 130 to the sub-tank 121, By providing the tubes constituting the ink flow path for returning ink to the main tank unit 130 independently, the air remaining in the tubes when returning ink to the main tank unit 130 is transferred from the main tank unit 130 to the sub tank 121. A prototype ink jet printer that prevents the ink from flowing into a tube that supplies ink to the printer was studied.

  However, in this solution, each sub tank 121 and the corresponding main tank unit 130 are connected by at least two tubes, and when the recording head unit 100 reciprocates, these two tubes are used. Since the recording head unit 100 is bent and deformed along with the reciprocating movement of the recording head unit 100, a large resistance force is generated when the recording head unit 100 is reciprocated, making it difficult to smoothly reciprocate the recording head unit 100. It was.

  On the other hand, in the present embodiment, since the flow path branching unit 150 is provided in the fixed area 140B in the middle of the ink flow path 140, at least the movable ink flow path from the main tank unit 130 to the sub tank 121 is movable. In the area 140A, the sub tank 121 and the flow path branching unit 150 are connected to each other by one ink flow path 140 for each color.

  Therefore, since it is possible to suppress an increase in resistance force when the recording head unit 100 is reciprocated, the recording head unit 100 can be smoothly reciprocated, so that print quality can be improved.

  In the present embodiment, since the second flow path port 121B communicates with the space above the sub tank 121, the air in the sub tank 121 is discharged to the ink flow path 140 with priority over the ink. Therefore, the air in the sub tank 121 can be reliably removed without increasing the amount of ink returned to the main tank unit 130.

  By the way, when the rigidity of the members constituting the ink flow path 140 is lowered to improve the flexibility, the gas permeability increases, so that the water in the ink staying in the ink flow path 140 evaporates and the ink flow path is increased. The viscosity of the ink inside increases, and the fluidity of the ink deteriorates.

  On the other hand, if the gas permeability of the member constituting the ink flow path 140 is decreased, the rigidity is increased and the flexibility is deteriorated, so that the resistance force when the recording head unit 100 is reciprocated is increased.

  On the other hand, in the present embodiment, the gas permeability of the members constituting the ink flow path from the flow path branch unit 150 to the main tank unit 130 forms the ink flow path from the flow path branch unit 150 to the sub tank 121. The gas flow rate of the member is smaller than that of the member to be used, so that the ink flow path is secured while ensuring the flexibility and suppressing the resistance force when the recording head unit 100 is reciprocated. It is possible to suppress the water in the ink staying at 140 from evaporating.

(Other embodiments)
In the above-described embodiment, the ink is circulated through the ink flow path 140 by the pump action due to the volume deformation of the sub tank 121. However, the present invention is not limited to this, and a dedicated pump such as a tube pump may be provided. Good. In this case, the sub tank 121 may not be deformable.

  Further, in the above-described embodiment, the flow path branch unit 150 is provided with the movable area 140A, the fixed area 140B, and the connection section, but the flow path branch unit 150 is provided, but the present invention is not limited to this.

  Moreover, in the above-mentioned embodiment. In order to allow the second flow path port 121B to communicate with the upper space of the sub tank 121, the second flow path port 121B is provided on the upper side of the sub tank 121. However, the present invention is not limited to this. For example, the second flow path port 121B may be provided below the sub tank 121, and the second flow path port 121B and the upper space of the sub tank 121 may be communicated with each other by a flexible tube.

  In the above-described embodiment, the gas permeability in the ink channels 141 and 142 from the channel branch unit 150 to the main tank unit 130 is the same as that in the ink channel 143 from the channel branch unit 150 to the sub tank 121. Although the present invention is smaller, the present invention is not limited to this. For example, the ink flow paths 141 to 143 are all constituted by the same tube, and the flow path branching unit 150 is fixed to the apparatus main body. Thus, the ink flow paths 141 and 142 may be fixed to the apparatus main body.

In the above-described embodiment, the flow branch unit 150 is configured by two check valves, but the present invention is not limited to this.
Further, the present invention is not limited to the above-described embodiment as long as it matches the gist of the invention described in the claims.

It is the schematic diagram which looked at the image forming part of the ink jet printer concerning this embodiment from the upper part side. 2 is a cross-sectional view showing the structure of ink flow paths 141 and 142 in the ink jet printer according to the present embodiment. FIG. It is a figure which shows the state of the press mechanism 160 in the normal time in the inkjet printer which concerns on this embodiment. It is a figure which shows the operation state at the time of removing the air in the subtank 121 in the inkjet printer which concerns on this embodiment.

Explanation of symbols

100: Recording head unit, 110: Recording head, 120: Sub tank unit,
121 ... Sub tank, 121A ... First flow path port, 121B ... Second flow path port,
122 ... Pressing lever, 130 ... Main tank unit,
131 ... Ink cartridge, 140 ... Ink flow path, 140A ... Range of motion,
140B ... fixed area, 144 ... plate, 144A ... groove,
150: Channel branch unit, 151: Sub tank side channel port,
152 ... 1st main tank side channel port, 153 ... 2nd main tank side channel port,
154: first check valve, 155: second check valve, 160: pressing mechanism,
161 ... slide cam, 162 ... push rod, 163 ... cam surface,
164 ... Spring for return, 165 ... Base plate, 165A ... Rack gear,
166: Pinion gear, 170: Paper discharge roller, 170A: Gear.

Claims (6)

A main tank that is fixed to the device body and stores ink;
A recording head that ejects ink toward a recording medium; a head unit that supplies ink to the recording head and has a sub-tank whose volume can be expanded and contracted; and a head unit that reciprocates in a predetermined scanning direction;
A sub-tank side channel port connected to the sub-tank side; a first main tank-side channel port and a second main tank-side channel port connected to the main tank side; A flow path branching unit that allows only the flow of ink to the sub tank side flow path port and the flow of ink from the sub tank flow path port to the second main tank side flow path port ;
A paper discharge roller for transporting the recording medium to the discharge port side;
A pressing lever that presses the sub-tank so as to reduce and deform the sub-tank,
A pressing mechanism that obtains a driving force from the paper discharge roller and presses the pressing lever ;
The pumping action due to volume variations of said sub-tank, an ink jet printer, characterized in Rukoto ink caused to flow into the ink flow path. An actuator that switches between a transmittable state in which a driving force can be transmitted from the paper discharge roller to the pressing mechanism and a non-transmittable state in which a driving force cannot be transmitted from the paper discharge roller to the pressing mechanism;
The pressing mechanism is disposed at a position shifted from a conveyance path through which the recording medium is conveyed,
Furthermore, the when the transmitting state, the head unit, an ink jet printer according to claim 1, characterized in Rukoto positioned at a position shifted from the conveyance path. The pressing mechanism is
A gear provided on the same shaft as the paper discharge roller and rotating together with the paper discharge roller;
Having a pinion gear that meshes with the gear and is movable between a position where the transmission is possible and a position where the transmission is impossible;
The inkjet printer according to claim 2 , wherein the actuator switches the transmission state of the driving force by moving the pinion gear . The ink flow path from the main tank to the sub tank is configured to have a movable area that is displaced with the reciprocating movement of the head unit, and a fixed area that is fixed to the apparatus main body.
The inkjet printer according to any one of claims 1 to 3 , wherein the flow path branching unit is provided in the fixed area in the middle of the ink flow path . The ink jet printer according to any one of claims 1 to 4 , wherein the sub tank is configured such that air in the sub tank is discharged to the ink flow path preferentially over ink. A gas permeability of a member constituting an ink flow path from the flow path branch unit to the main tank is smaller than a gas permeability of a member constituting an ink flow path from the flow path branch unit to the sub tank. An ink jet printer according to any one of claims 1 to 5.

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