JP6167475B2 - Liquid ejecting apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid ejection apparatus and an image forming apparatus, and more particularly to a liquid supply mechanism.

  As is well known, a printer, a facsimile machine, a copying machine, and an image forming apparatus provided with a combination of these functions include a liquid ejection apparatus having a recording head composed of a liquid ejection head that ejects liquid droplets such as ink. The configuration used is known.

In a liquid ejection apparatus, an image is formed by adhering or penetrating droplets ejected from a recording head while conveying a recording medium such as recording paper.
The target of the recording medium includes not only the recording paper described above but also a material capable of adhering or penetrating liquids such as fibers such as intention, leather and metal, resin, glass, wood and ceramics.

  In an image forming apparatus provided with a liquid discharge device, in order to stabilize the ink discharge operation from the liquid discharge head, the ink in the liquid discharge head is maintained at a predetermined negative pressure (acts on the ink in the liquid discharge head). It is important to keep the pressure to be a predetermined negative pressure). For this reason, in general, an ink supply system that supplies ink to the liquid discharge head is provided with a negative pressure generating means, and ink to which negative pressure is applied by the negative pressure generating means is supplied to the liquid discharge head.

  As such a negative pressure generating means, a configuration in which a negative pressure is formed by utilizing the capillary phenomenon of a sponge-like ink absorber housed in the ink tank, or an ink tank so as to maintain the negative pressure in the ink tank There has been known a configuration provided with a biasing means such as a spring for biasing a flexible member forming at least a part of the ink cartridge to the outside of the ink tank. Further, as another negative pressure generating means, there is also known a configuration in which an ink tank is disposed below the liquid discharge head and a negative pressure is applied to the ink using a water head difference.

On the other hand, liquids such as ink filled in the nozzles may thicken and harden when dried, or bubbles may be included in the liquid.
Such a decrease prevents normal discharge of the liquid, and it is known to provide a maintenance and recovery device for maintaining and recovering the function of the nozzle.
The maintenance / recovery device is known to include a cap unit that covers and moisturizes the nozzle and a unit that sucks the inside of the nozzle and collects the thickened liquid in the nozzle in a waste liquid tank or the like.

By the way, in the liquid ejection device, when using liquids of a plurality of colors, not only a liquid supply pump is required for each color liquid supply path, but also a suction pump used for a maintenance recovery device for each nozzle is provided for each nozzle. Is required.
For this reason, there exists a possibility of causing the enlargement and complexity of a structure for the reason of installing the drive source which drives many pumps.

  Therefore, a single drive source for driving the planetary gear mechanism is provided in the drive path of each pump, and a selection drive mechanism for setting the pump selection and the liquid supply state and the pump pause state according to the drive direction switching of the drive source A configuration with the above has been proposed. (For example, patent document 1).

  In the configuration disclosed in Patent Document 1, liquid in the tube is supplied in a pump selected during normal rotation of the drive source, while the release operation of the pump is performed during reverse rotation of the drive source. For this reason, the operation direction of the drive source is related to the pumping operation and the selection of the pump, and the drive source cannot be used in a simple operation such as continuous rotation in one direction.

  In particular, since the pump release operation is performed during the reverse rotation of the drive source, it is impossible to perform the liquid supply operation and the suction operation by the maintenance / recovery mechanism during the reverse rotation, and the use state of the drive source described above is specified. End up. For this reason, even when a single drive source is used, the drive relationship for operating the pump can be obtained only under a predetermined condition, and the degree of freedom of operation of the drive source is low. There is a problem that liquid supply and suction operations cannot be performed by the pump without addition.

  An object of the present invention is to reduce the size and simplification of the apparatus by saving the drive source in view of the problems in the above-described conventional liquid ejection apparatus, and to prevent the operation of the drive source from being restricted and to have a simple structure. Accordingly, an object of the present invention is to provide a liquid ejection apparatus and an image forming apparatus having a configuration capable of downsizing and simplifying the apparatus described above.

In order to achieve this object, the present invention provides a plurality of ejection heads for ejecting different types of liquid droplets and a plurality of head tanks for supplying liquid to the ejection heads, which are arranged at predetermined positions and can be exchanged. A plurality of liquid main tanks and a flow path between the plurality of main tanks and the plurality of head tanks , supplying liquid from each main tank to the head tank, and from the head tank to the main tank And a plurality of liquid feed pumps that reversely feed the liquid, and a single first drive source that simultaneously and uniformly drives the plurality of liquid feed pumps ; A flow path switching mechanism that is disposed between the plurality of liquid feed pumps and the corresponding plurality of head tanks, and is capable of switching the flow path to either an open state or a closed state; Sandwich the pump A circulation flow path connected to the upstream and downstream sides of the flow direction of the liquid in the flow path, and a second drive source for driving the flow path switching mechanism, wherein the flow path switching mechanism includes the second drive. A flow path provided with the plurality of liquid feed pumps by being driven by a source; a flow path for liquid from the liquid feed pump toward the head tank in the open state; and a circulation path in the closed state. The liquid discharge apparatus is characterized by switching to a flow path to be directed.

According to the present invention, since the first drive source capable of driving each pump is shared as a member for driving a plurality of pumps, it is not necessary to provide a drive source for each pump.
In addition, when the drive source of each pump is shared, the flow path switching mechanism selectively opens and closes the flow path to the head tank to be supplied or the suction flow path from the cap member used in the maintenance and recovery mechanism. Since pressure fluctuations in unselected flow paths are suppressed by introduction and circulation into the circulation flow path, even when a single drive source is used, it is selected by uniform operation without prescribing the operation of that drive source. Liquid feeding or suction recovery for only the flow path is possible.

1 is an external view of an image forming apparatus using a liquid ejection apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 3 is a plan view of the internal configuration shown in FIG. 2. FIG. 2 is an external view illustrating a configuration of a head unit used in the liquid ejection device illustrated in FIG. 1. It is a schematic diagram which shows the liquid supply path | route used for the liquid discharge apparatus shown in FIG. It is a schematic diagram for demonstrating the drive structure of the pump used for the liquid discharge apparatus shown in FIG. It is a figure for demonstrating the structure of the flow-path switching mechanism used for the liquid discharge apparatus shown in FIG. It is a schematic diagram for demonstrating the principal part structure of the maintenance recovery mechanism used for the liquid discharge apparatus shown in FIG. It is a figure for demonstrating the suction structure used for the maintenance recovery mechanism shown in FIG. It is a figure for demonstrating the modification of the flow-path switching mechanism shown in FIG. It is a schematic diagram for demonstrating another embodiment regarding the liquid supply flow path shown in FIG.

The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is an external view of an image forming apparatus using a night liquid ejecting apparatus according to the present invention.
The image forming apparatus shown in FIG. 1 has an apparatus main body 1, a paper feed tray 2 for loading paper mounted on the apparatus main body 1, and a detachably mounted on the apparatus main body 1 to record images ( And a paper discharge tray 3 for stocking the formed paper.
Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons and a display.

  The cartridge loading unit 4 is used as a plurality of main tanks containing inks that are different color materials, for example, black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. Ink cartridges 10k, 10c, 10m, and 10y (referred to as “ink cartridge 10” when colors are not distinguished) are inserted from the front side to the rear side of the apparatus main body 1 and can be loaded. A front cover (cartridge cover) 6 that is opened when the ink cartridge 10 is attached / detached is provided on the front side of 4 to be openable and closable.

Next, the mechanism part of this liquid discharge apparatus will be described with reference to FIGS. 2 is a schematic side view illustrating the outline of the mechanism, and FIG. 3 is an explanatory plan view of the main part.
In FIG. 3, a carriage 33 is slidably held in a main scanning direction by a guide rod 31 which is a guide member horizontally mounted on the left and right side plates 21A and 21B and a stay 32, and a timing belt is interposed by a main scanning motor (not shown). In FIG. 3, the scanning is moved in the direction indicated by the arrow (carriage main scanning direction).

  The carriage 33 has liquid ejection heads 34a, 34b, 34c, 34d for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). A liquid discharge head 34 ”) is arranged in a sub-scanning direction orthogonal to the main scanning direction, and the ink droplet discharge direction is directed downward.

  In FIG. 2, the liquid discharge head 34 can discharge black (K), cyan (C), magenta (M), and yellow (Y) ink droplets, respectively.

  As an ink jet head constituting the liquid discharge head 34, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator using an electrostatic force, an electrostatic actuator using an electrostatic force, and the like provided as pressure generating means for generating a pressure for discharging a droplet can be used.

The carriage 33 has head tanks 35k, 35c, 35m, and 35y as liquid storage containers that supply ink of each color corresponding to the nozzle rows of the liquid discharge head 34 (referred to as “head tank 35” when not distinguished). ) Is installed. As described above, the head tank 35 is supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 via the ink supply tube 36 of each color. In FIG. 3, reference numeral 36 a indicates a suction flow path at the time of idle driving, and communicates with a waste liquid tank (not shown).
The cartridge loading unit 4 is provided with a liquid feed pump unit 24 for feeding ink in the ink cartridge 10.

  On the other hand, as shown in FIG. 2, the sheets 42 are separated one by one from the sheet stacking section 41 as a sheet feeding section for feeding the sheets 42 stacked on the sheet stacking section (pressure plate) 41 of the sheet feeding tray 2. A half paddle (feeding roller) 43 to be fed and a separation pad 44 made of a material having a large friction coefficient are provided opposite to the feeding roller 43, and this separation pad 44 is urged toward the feeding roller 43 side.

  In order to feed the paper 42 fed from the paper feed unit to the lower side of the liquid discharge head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller 49 are provided. And a conveying belt 51 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the liquid ejection head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. The transport belt 51 rotates in the belt transport direction of FIG. 3 when the transport roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  As a paper discharge unit for discharging the paper 42 recorded by the liquid ejection head 34, a separation claw 27 for separating the paper 42 from the transport belt 51, a paper discharge roller 61, and a paper discharge roller 62 are provided. A paper discharge tray 3 is provided below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the transport belt 51, reverses it, and feeds it again between the counter roller 46 and the transport belt 51. Further, the upper surface of the duplex unit 71 is used as a manual feed tray 72.

  As shown in FIG. 3, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the liquid ejection head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. .

  The maintenance / recovery mechanism 81 includes cap members for capping each nozzle surface of the liquid ejection head 34 (for convenience, collectively indicated by reference numeral 82), and a wiper blade 83 that is a blade member for wiping the nozzle surface. Also, an empty discharge receiver 84 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording in order to discharge thickened ink is provided.

  As shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 33, the liquid used when performing the idle ejection for ejecting the liquid droplets that do not contribute to the recording in order to discharge the ink that has been thickened during the recording or the like. An empty discharge receiver 88 for receiving droplets is arranged, and the empty discharge receiver 88 is provided with an opening along the nozzle row direction of the liquid discharge head 34 (generally indicated by reference numeral 89 for convenience).

  In the ink liquid ejecting apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide member 45, It is sandwiched between the counter roller 46 and conveyed, and the leading end is guided by the conveying guide 47 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated with respect to the charging roller 56, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, in a sub-scanning direction that is a circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  By driving the liquid ejection head 34 in accordance with the image signal in the process of moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and the paper 42 is conveyed by a predetermined amount. Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, the carriage 33 moves to the maintenance / recovery mechanism 81 side during printing (recording) standby. When the carriage 33 moves, the liquid ejection head 34 is capped by the caps 82 (a to d). By maintaining the nozzle in a wet state, ejection failure due to ink drying is prevented. Further, with the liquid ejection head 34 being capped by the cap 82, the ink is sucked from the nozzle by a suction pump (not shown) (referred to as “nozzle suction” or “head suction”), and the ink or bubbles that are thickened are discharged. Perform the action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the liquid ejection head 34 is maintained.

FIG. 4 shows a liquid discharge head unit used in the image forming apparatus.
In FIG. 4, the liquid ejection head unit includes one liquid ejection head 34, a head tank 35 for supplying recording liquids of the same color or different colors to the four nozzle rows of the one liquid ejection head 34, A filter unit 35A interposed between the liquid discharge head 34 and a flexible cable for transmitting a signal for driving the actuator means of the liquid discharge head 34 is drawn from the liquid discharge head 34 (not shown). It is.

The head tank 35 is formed with an ink storage portion which is a recording liquid storage portion on both sides of the tank main body 35B. Although not shown in detail, a flexible film-like member (possible to the opening of these ink storage portions). A flexible film-like member) is adhered and sealed by adhesion or welding.
A spring (spring: not shown), which is an elastic member for urging the film-like member (not shown) outward, is provided between the tank body 35B and the film-like member inside the ink containing portion. These film-like members and elastic members constitute a negative pressure generating mechanism. Further, a negative pressure detection lever 35C that is displaced in accordance with the displacement of the film-like member is mounted on the tank body 35B so as to be swingable.

At the upper part of the tank main body 35B, an air opening / closing mechanism 37 is provided as a pressure control means for opening and closing an air opening passage provided to open the ink containing portion to the air.
The air opening / closing mechanism 37 uses an opening / closing valve capable of communicating or blocking between the ink container and the atmosphere, and is opened when the air accumulated in the ink container is discharged to the outside. The opening / closing operation of the opening / closing valve is performed when it is pressed by an actuator (not shown).

  The tank main body 35B is formed with an ink supply port portion 38 for supplying ink to the ink storage portion, and a tube indicated by reference numeral 36 in FIG.

The characteristics of the present embodiment will be described as follows with the above configuration as an object.
The feature of the present embodiment is that the liquid feed pump P1 provided for each liquid discharge head 34 is driven by a single drive source, while the target pump to be supplied is selected. This is to prevent fluctuations in the pressure of the ink in the liquid supply flow path, particularly the pressure increase, due to the continued drive of the pump that has not been performed.

FIG. 5 is a schematic diagram showing a liquid supply path from the ink cartridge 10 to the head tank 35.
In FIG. 5, a supply channel 103 is provided in the liquid supply path from the ink cartridge 10 to the head tank 35, and the ink that is liquid passes through the liquid feed pump P <b> 1 disposed in the supply channel 103. The liquid is sent to the tank 35. The liquid feed pump P1 is disposed in the pump unit indicated by reference numeral 24 in FIG.
The liquid feed pump P1 is configured to be able to send liquid to the head tank 35 and return ink from the head tank 35 to the ink cartridge 10 by selecting forward / reverse driving. By returning the ink from the head tank 35 to the ink cartridge 10, the pressure in the head tank 35 is adjusted.

  On the other hand, in the supply flow path 103 provided between the ink cartridges 10 of each color and the head tank 35, the ink moving direction (hereinafter also referred to as the liquid supply direction) upstream and downstream with the liquid feed pump P1 interposed therebetween. A circulation channel 104 having an end connected to each side is provided on the side, and the supply channel 103 to which the circulation channel 104 is connected is configured to open and close the supply channel 103 for each color to flow ink. Are arranged in order.

Here, the drive structure of the liquid feed pump P1 will be described with reference to FIG.
In FIG. 6, the number of liquid feed pumps P <b> 1 corresponding to each head tank 35 is provided, and the drive is performed by a single drive source 105.
That is, the common drive gear 106 which meshes with the transmission gears 107a to 107d provided for each liquid feed pump P1 is attached to the output shaft of the drive source 105.
Thus, the rotations of the drive gear 106 are transmitted to the transmission gears 107a to 107d all at once, so that each liquid feed pump P1 is uniformly driven. In FIG. 5, a thick arrow indicates a power transmission path during forward and reverse rotation.

  The drive source 105 uses a motor that can rotate forward and backward, and supplies ink toward the head tank 35 during forward rotation, and returns ink from the head tank 35 toward the ink cartridge 10 during reverse rotation as described above. It is said that.

  On the other hand, the flow path switching mechanism 100 is a member for selecting a flow path to the head tank 35 to be supplied according to the remaining amount of ink on the head tank 35 side, and its configuration is shown in FIG. ing.

As shown in FIG. 7B, the flow path switching mechanism 100 is connected to a rotary shaft 114 that is linked to a second drive source (not shown) provided separately from the drive source 105 of the liquid feed pump P1 described above. The inner ring 113 is attached and rotatable, and the outer ring 115 is a fixed ring disposed on the outer periphery of the inner ring 113.
The inner ring 113 is disposed at a position connected to the upstream and downstream sides of the supply flow path 103 across the position where the flow path switching mechanism 100 is disposed, and includes a flow path communicating with the supply flow path 103 inside. At the same time, a recess 116 is provided in a part of the circumferential direction to accommodate a tube used for the supply flow path 103 (for convenience, indicated by reference numerals 103a to 103c) with an original outer diameter.

The outer ring 115 is a tube used in the supply flow path 103 as a gap between the outer ring surface of the inner ring 113 (for convenience, three tubes 103a to 103c are shown in the figure, but actually, the ink cartridge 10 4 tubes are used in accordance with the number of tubes) and are arranged in a ring shape that can be squeezed to close the tube. A recess having an extremely shallow depth capable of performing the above is formed.
Therefore, the inner ring 113 functions as a pressing member for the tube.
In the configuration shown in FIG. 7, the corners at both ends of the recess along the circumferential direction are provided with a pull-out angle so that the tube can be easily pulled out when the inner ring 113 rotates, and the tube is dragged when the inner ring 113 rotates. There has been no such thing.

In the flow path switching mechanism 100, the concave portion 116 of the inner ring 113 is positioned corresponding to the position of the tube 103 corresponding to the selected supply flow path, whereby the supply flow path in which the tube is restored to the original outer diameter size. Is released.
The other tubes are kept closed by being crushed by the outer peripheral surface of the inner ring 113 and the inner peripheral surface of the outer ring 115.

  In addition, instead of the combination structure of the inner ring 113 and the outer ring 115 described above, as shown in FIG. 7C, it is provided so as to be movable in parallel with respect to a fixed base (indicated by reference numeral 115 ′ for convenience). A pressing member (indicated by reference numeral 113 'for convenience) having a recess (for convenience, indicated by reference numeral 113A') provided on the surface facing the base 115 'is provided. The movement in the horizontal direction may be governed by the drive gear GR meshing with the tooth portion 113B ′ formed in the portion. Also in this case, with respect to the edge shape of the recess, a clearance angle is provided as in the case described above.

On the other hand, the circulation channel 104 described above is when the liquid supply is continued from the liquid feed pump P1 that is uniformly driven by the single drive source 105 in the supply channel not selected by the channel switching mechanism 100. This is a configuration for suppressing an increase in pressure in the supply flow path.
For this reason, in the closed supply flow path, the ink supplied from the ink cartridge 10 enters the circulation flow path 104 and circulates.

As shown in FIG. 5A, the flow path switching mechanism 100 disposed in the supply flow path 103 including the circulation flow path 104 is arranged in the ink supply direction in the supply flow path 103 across the liquid feed pump P1. When arranged upstream of the liquid feed pump P1, and as shown in FIG. 5B, the supply flow path 103 may be arranged downstream of the liquid feed pump P1 in the ink supply direction.
In the arrangement shown in FIG. 5A, it is not necessary to mix with the ink sent out from the ink cartridge 10, and in the structure shown in FIG. 5B, pressure fluctuations when ink is circulated are discharged. It is possible not to tell the head side.

  Since the present embodiment is configured as described above, the liquid feed pump P1 provided in the ink supply flow path for each color can be driven by a single drive source 105. As a result, it is not necessary to provide a drive source for the liquid feed pump in each supply flow path, so that the installation space for these drive sources can be reduced in size and simplified.

On the other hand, when a plurality of liquid feed pumps P1 are uniformly driven by a single drive source 105, the supply flow path 103 is selected by the flow path switching mechanism 100 according to the remaining amount of ink in the head tank 35. The As a result, inadvertent supply of ink to the head tank 35 that does not require ink feeding is reliably prevented.
In particular, in a channel not selected, a liquid whose pressure is increased by driving a pump can be circulated in the circulation channel. For this reason, when all pumps are driven by a single drive source, it is possible to prevent the pressure fluctuation of the liquid in the flow path that is not selected and the pressure fluctuation from reaching the liquid discharge head.
As a result, excessive ink supply is avoided and an appropriate ink amount in the head tank 35 is maintained. As a result, it is possible to maintain an appropriate amount of liquid discharge at a predetermined pressure in the liquid discharge head.

  In addition, when one of the tubes used for the supply flow path 103 is selected by the flow path switching mechanism 100, the liquid feed pump P1 is driven by the single drive source 105, The pressure in the supply channel 103 not selected increases. However, in the present embodiment, inadvertent pressure fluctuations in the supply channel 103 can be suppressed by circulating ink in the circulation channel 104. As a result, it is possible to maintain an appropriate amount of ink discharge state without causing pressure fluctuations in the discharge head.

Next, a modification of the main part of the present embodiment will be described.
This configuration is characterized in that the fluid resistance in the circulation flow path 104 connected to the supply flow path 103 is different.
That is, in FIG. 5, the fluid in the circulation channel 104 is reduced by reducing the channel diameter (d1) of the circulation channel 104 with respect to the channel diameter (d0) of the supply channel 103, as indicated by symbols d0 and d1. The mechanism has been improved.
Thereby, it can prevent that the liquid feeding efficiency in the supply flow path 103 falls.

  Although not shown in the drawings, the connection position of the circulation flow path 104 with respect to the supply flow path 103, in other words, the supply flow path 103 and the circulation flow path is not shown as a configuration for preventing such a decrease in liquid feeding efficiency in the supply flow path 103. The same effect may be obtained by adopting a configuration in which the flow path on the circulation flow path 104 side is narrowed at the confluence position with 104.

Next, another embodiment according to the present invention will be described.
In the present embodiment, the suction pump provided in the suction flow path used in the maintenance and recovery mechanism of the ejection head is driven by a single drive source as described above, and the suction flow path can be opened and closed sequentially. It is characterized in that a flow path switching mechanism is provided.
FIG. 8 is a schematic diagram showing the configuration of the suction path for the maintenance / recovery mechanism 81 of the ejection head 34.
The maintenance / recovery mechanism 81 is provided with a cap 82 facing the discharge head 34. The cap 82 is idled via a suction flow path 110 in which a suction pump P2 is disposed (see FIG. 2). Is connected to an opening 89 (see FIG. 2).

The suction pump P2 is uniformly driven for each color by a single drive source 105 for the liquid feed pump P1.
The cap 82 is separated from the discharge head 34 when ink is supplied and returned by the liquid supply pump P1 shown in FIG. 5, and the cap 82 is discharged when the liquid supply pump P1 and the suction pump P2 are driven simultaneously. Is not affected by
As a result, the drive source of the suction pump P2 provided in the suction flow path 110 can be used also as the drive source 105 of the liquid feed pump P12, so that the configuration of the drive source when a plurality of types of pumps are used is simplified. be able to.
In FIG. 8, reference numerals 105 and 106 indicate the drive source and the drive gear in FIG. 6, respectively, and the thick arrows indicate drive paths.

On the other hand, as shown in FIG. 9A, one suction channel 110 is selected and opened / closed by the channel switching mechanism 100 ′, like the supply channel 103.
The flow path switching mechanism 100 ′ used in the configuration shown in FIG. 9A is an on-off valve.
That is, when any one of the supply flow paths 103 is opened, ink is sent from the supply flow path 103 toward the head tank 35, while the liquid supply pump P 1 and the suction pump P 2 driven by the drive source 105 are used. When the suction operation is performed, the cap 82 covers the ejection head 34 to make it wet and prevent drying.

By the way, as described above, when the suction pump P2 is driven simultaneously with the liquid feed pump P1, when the liquid feed pump P1 is reversed, the suction pump P2 is also reversed, and the reverse flow of the ink in the suction channel 110 In addition, the flow path switching mechanism 100 ′ may be damaged.
Therefore, in this embodiment, as shown in FIG. 9B, in the suction flow path 110, the circulation flow in which ends are connected to the upstream and downstream sides of the ink movement direction (suction direction) with the suction pump P2 interposed therebetween. A path 111 is provided.

  The circulation flow path 111 is a part that circulates the ink in the suction flow path 110 when the liquid feed pump P1 is reversed. With this configuration, the reverse flow of the ink in the suction flow path 110 and the flow path switching mechanism 100 ′ are performed. Can be prevented. Regarding the flow path resistance in this case, as shown in FIG. 8, the flow path resistance in the circulation flow path 111 is increased as in the relationship between the supply flow path 103 and the circulation flow path 104.

Thereby, the fall of suction efficiency can be controlled.
In addition, instead of providing the circulation channel 111, when the liquid feeding pump P1 is in the liquid feeding state, the liquid feeding pump is configured to have a transmission structure in which the suction pump P2 can obtain a rotational relationship capable of sucking thickened ink or the like from the ejection head. When P1 rotates in a direction to return ink, it is possible to prevent backflow or the like in the suction flow path 110.

  On the other hand, regarding the flow path switching mechanism described above, not only the supply flow path 103 and the suction flow path 110 but also the circulation flow path 104 or 111 can be provided.

  In other words, in order to prevent the liquid feeding efficiency from being lowered, it is possible to change the flow path diameters of the supply flow path 103 and the circulation flow path 104 as shown in FIG. In the open state, there is no ink flowing into the circulation flow path 104, so it cannot be denied that the liquid feeding efficiency is somewhat reduced.

  Therefore, as shown in FIG. 10, the flow path switching mechanism is also provided in the circulation flow path (in FIG. 9, for the sake of convenience, the supply flow path 103 and the circulation flow path 104), and the liquid supply process is in progress. When the supply channel 103 is opened, the circulation channel 104 connected to the supply channel 103 is closed.

In FIG. 10, the supply flow path switching mechanism 100a and the circulation flow path switching mechanism 100b are rotatably provided in synchronization with the same drive source (not shown).
The supply flow path switching mechanism 100a has the same configuration as that described in FIG. 7, and closes the selected supply flow path 103 by opening and crushing the tube. In FIG. 7, the tubes on the supply flow path switching mechanism 100a side are indicated by reference numerals 103a to 103d, the inner ring is indicated by reference numeral 113a, and the outer ring is indicated by reference numeral 115A.

  On the other hand, the circulation flow path switching mechanism 100b is configured by combining an inner ring 113b and an outer ring 115b that can be rotated by a rotating shaft 114 ′, as in the case shown in FIG. In the direction, unlike the case shown in FIG. 6, the circulation channels 104 a to 104 d or the circulation channel 111 are arranged adjacent to either the supply channels 103 a to 103 d or the suction channel 110.

  The inner ring 113b is different in shape from the case shown in FIG. 6, and a convex portion 113b1 is formed in a part of the circumferential direction instead of a concave portion. On the inner peripheral surface of the outer ring 115b facing the inner ring 113b, the tubes used for the supply flow paths 103a to 103d or the circulation flow paths 104a to 104d are maintained in their original outer diameter shape when the convex portion 113b1 of the inner ring 113b is not opposed. A recess having an extremely shallow depth is formed with a gap that can be formed. In this case, the configuration related to the corners of the recess is the same as that shown in FIG.

In the circulation channel switching mechanism 100b, when the supply channel switching mechanism 100a is open except for one of the supply channels 103 according to the rotational position of the inner ring 113a, the circulation channel switching mechanism 100a is adjacent to the opened supply channel 103. The circulating flow path 104 is closed.
Therefore, the supply flow path that is opened and the liquid supply state or the suction flow path that is in the suction state can reduce the liquid supply efficiency or the suction efficiency by closing the circulation flow path connected to the supply flow path. Absent.

FIG. 11 is a schematic diagram in the case where the flow path switching mechanism 100 described in FIG. 6 is provided for the liquid supply path intended for the configuration including the circulation flow paths 104 and 111 shown in FIGS. It is a figure which shows a flow-path structure.
In the same figure, the liquid feed pump P1 and the suction pump P2 are uniformly driven by the same drive source 105, and at the position where ink is sent out from the liquid feed pump P1, each flow path 103, A flow path switching mechanism 100 having a tube used for 110 is arranged. In the flow path switching mechanism 100 in this case, in addition to the supply flow path 103 in the configuration shown in FIG. 6, the suction flow path 110 is disposed in a part of the inner ring 113 and the outer ring 15 in the circumferential direction.

In this configuration, when the head tank 35 that requires ink feeding is selected, the flow path switching is performed so as to open the supply flow path connected to the head tank 35 as described in FIG. The mechanism 100 is activated.
In the supply channel that is not selected, the ink fed into the supply channel is circulated by entering the circulation channel 104 by continuously driving the liquid feed pump P1.

  On the other hand, the suction pump P2 is also driven together with the liquid feed pump P1, and particularly when the liquid feed pump P1 is set to rotate in a direction to return ink, the suction pump P2 is moved when the liquid feed pump P1 is feeding. By utilizing the rotational relationship of suction, it is possible to suck ink that has been thickened simultaneously with liquid feeding.

As described above, in the present embodiment, the drive source for driving the plurality of pumps can be unified, so that the apparatus can be prevented from becoming large and complicated.
In addition, when a single supply channel selected using a single drive source is supplied to the target, the supply flow channel is maintained when the liquid supply is continued by driving the liquid supply pump of the supply channel that was not selected. Inadvertent pressure rise or backflow in the suction flow path is not affected by pressure fluctuations on the discharge head side as ink is circulated through the circulation flow path. As a result, pressure fluctuation at the ejection head is suppressed and proper ink ejection is maintained.

In the present embodiment, a liquid feed pump or a suction pump is provided not in the circulation flow path but in the supply flow path or the suction flow path, and a flow path switching mechanism is disposed on the side where the ink is delivered from the liquid feed or suction pump. Since ink reaching the path switching mechanism is introduced into the circulation flow path, pressure fluctuations in the liquid feeding or suction flow path are not exerted on the ejection head.
In other words, when liquid feeding or suction from the circulation channel is performed only by changing the fluid resistance in the supply or suction channel, the ink that tries to enter the suction channel with the liquid is directly passed to the circulation channel. Thus, it is possible to prevent the pressure fluctuation in the circulation flow path or the pressure fluctuation from acting on the ejection head as it is.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 10 Ink cartridge 34 Liquid discharge head 35 Head tank 100,100a, 100b Flow path switching mechanism 103 Supply flow path 104 Circulation flow path 105 1st drive source 110 Suction flow path P1 Liquid feed pump P2 Suction pump

Japanese Patent No. 4019694

Claims (8)

A plurality of ejection heads for ejecting different types of liquid droplets; a plurality of head tanks for supplying liquid to the ejection heads; a plurality of liquid main tanks disposed at predetermined positions and replaceable ; A plurality of liquid feeding units disposed in a flow path between a main tank and the plurality of head tanks , supplying liquid from each main tank to the head tank, and returning the liquid from the head tank to the main tank. A liquid discharge device comprising a pump,
A single first drive source for uniformly driving the plurality of liquid feeding pumps simultaneously;
A flow path switching mechanism disposed between the plurality of liquid feeding pumps of the flow path and the corresponding plurality of head tanks, and capable of switching the flow path to either an open state or a closed state, respectively. ,
Circulation flow paths connected to the upstream and downstream sides of the flow direction of the liquid in the flow path across the liquid feed pump,
A second drive source for driving the flow path switching mechanism,
The flow path switching mechanism is driven by the second drive source to flow through the flow path including the plurality of liquid feed pumps, and to flow the liquid from the liquid feed pumps toward the head tank in the open state. A liquid ejection apparatus that switches between a path and a flow path toward the circulation flow path in the closed state.   The plurality of discharge heads are provided with a capping member that covers the plurality of discharge heads, and a suction pump that sucks liquid from the discharge heads, and the suction pump is driven by a first drive source that drives the liquid feed pump. The liquid ejecting apparatus according to claim 1, wherein   The flow path between the suction pump and the cap member is connected to the flow path switching mechanism, and the open / close state of the liquid flow path moving from the cap member can be switched. Liquid discharge device. A plurality of ejection heads for ejecting different types of liquid droplets, a plurality of head tanks for supplying liquid to the ejection heads, a plurality of liquid main tanks arranged at predetermined positions and replaceable, and each main tank A liquid discharge device comprising a plurality of liquid feed pumps for supplying liquid to the head tank from the head tank and back feeding the liquid from the head tank to the main tank,
A first drive source for simultaneously driving the plurality of liquid feed pumps;
A flow path switching mechanism disposed in a flow path between the plurality of main tanks and the corresponding plurality of head tanks, and capable of switching the flow path to either an open state or a closed state;
Circulation flow paths connected to the upstream and downstream sides of the flow direction of the liquid in the flow path across the liquid feed pump,
A second drive source for driving the flow path switching mechanism,
The flow path switching mechanism is driven by the second drive source to flow through the flow path including the plurality of liquid feed pumps, and to flow the liquid from the liquid feed pumps toward the head tank in the open state. A path and a flow path toward the circulation flow path by the closed state,
A capping member that covers the plurality of discharge heads and a suction pump that sucks liquid from the discharge heads via the capping member are provided, and the suction pump is driven by a first drive source that drives the liquid feed pump. Driven,
The flow path between the suction pump and the cap member is connected to the flow path switching mechanism, and the open / close state of the liquid flow path moving from the cap member is switched,
Wherein the flow path between the suction pump and the flow path switching mechanism, liquid discharge, characterized in that the circulation passage connected to the moving direction upstream and downstream side of the liquid across the suction pump is provided apparatus.   5. The liquid ejection device according to claim 1, wherein the circulation flow path has a fluid resistance larger than that of the flow direction of the liquid in the flow path on the downstream side. The flow path switching mechanism uses a flexible tube as a material of each flow path, and is configured with the flexible tube depending on whether the flexible tube is crushed or when the crush is released. The liquid discharge apparatus according to claim 1, wherein an open / close state of a flow path to be set can be set. The flow path switching mechanism includes a rotatable inner ring and an outer ring made of a fixed ring arranged on the outer periphery of the inner ring, and the inner ring can be depressed or crushed to return the annular tube to its original outer diameter. convex portions are provided, that you open and close the configured channel in the annular tube by crushing released or crushing of the annular tube by rotating to the position of the annular tube constituting the selected flow path The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device. An image forming apparatus comprising the use of a liquid ejecting apparatus according to one of the 請 Motomeko 1 to 7.

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