JP2011224909A - Inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printer that endures a necessary flow rate and a nozzle pressure, and has an ink circulation route reduced in ink flowing and dropping due to impact and vibration.SOLUTION: The inkjet printer includes an ink circulation route having: a recording unit having an ink head provided with a nozzle surface where a plurality of nozzles are formed; a first tank arranged above the nozzle surface in the direction of gravitational force and storing ink to be supplies to the recording unit; a second tank arranged below the nozzle surface in the direction of gravitational force, and collecting and storing ink from the recording unit; a first tube connecting the recording unit and the first tank; a second tube connecting the recording unit and the second tank; a third tube connecting the first tank and the second tank; and a pump for piping up ink in the second tank to the first tank, wherein the first tube serpentines in the direction of gravitational force.

Description

  The present invention relates to an ink jet printer having an ink circulation path.

  In general, an ink jet printer equipped with an ink head of a thermal head type or an electromechanical conversion element (piezo) type is known. This ink jet printer records an image on a recording medium such as recording paper by ejecting ink droplets from nozzles formed on an ink head.

  As an example of such an ink jet printer, one having an ink circulation path is known. For example, Patent Document 1 discloses a recording head (ink head), a first ink chamber provided above the recording head, a second ink chamber provided below the recording head, and the recording head. An ink jet printer is disclosed that includes an ink circulation path that includes a pipe that connects the first ink chamber and the second ink chamber and forms an ink flow path, and a pump. This ink circulation path supplies ink from the first ink chamber to the recording head and ejects it from the recording head due to the height difference (water head difference) of the arrangement positions of the recording head, the first ink chamber, and the second ink chamber. The ink that has not been collected is collected in the second ink chamber. Then, the ink collected in the second ink chamber is pumped up to the first ink chamber by the pump. Thus, the ink is circulated.

  In such an ink jet printer, the inside of the nozzle of the recording head is generally kept at a negative pressure. Due to this negative pressure, a meniscus in which the ink is recessed upward in the direction of gravity is formed in the nozzle, so that the ink does not drip from the nozzle. However, for example, if the meniscus is destroyed due to shock or vibration during transportation or replacement of the print head, and air enters the pipe connecting the first ink chamber and the print head, Ink in the first ink chamber flows down by replacing the air mixed with ink. In order to prevent this, in the ink circulation path of Patent Document 1, an electromagnetic valve is provided in a pipe connecting the first ink chamber and the recording head.

JP 2001-219580 A

  In the configuration in which ink flows from the first ink chamber to the second ink chamber via the recording head only by the water head difference as in the above-mentioned Patent Document 1, the first ink chamber and the recording head are connected to each other. If a solenoid valve is provided in the existing pipe, the flow resistance from the first ink chamber to the recording head increases, so that it becomes difficult to secure a necessary flow rate and nozzle pressure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer having an ink circulation path that secures a necessary flow rate and nozzle pressure and reduces ink flow-down due to impact and vibration.

  In one embodiment of the present invention, a recording unit having an ink head having a nozzle surface on which a plurality of nozzles are formed, and an ink that is disposed above the nozzle surface in the direction of gravity and stores the ink to be supplied to the recording unit. A first tank, a second tank disposed below the nozzle surface in the gravitational direction, collecting and storing ink from the recording unit, and connecting the recording unit and the first tank; A first tube, a second tube connecting the recording unit and the second tank, a third tube connecting the first tank and the second tank, A pump for pumping the ink in the second tank to the first tank, and the first tube is meandering in the direction of gravity. It is an inkjet printer.

  In one embodiment of the present invention, a recording unit having an ink head on which a plurality of nozzles for ejecting ink are formed, and a nozzle surface on which the plurality of nozzles are formed are arranged above the direction of gravity and supplied to the recording unit. An ink jet printer having an ink circulation unit having at least a tank for storing ink to be stored and a pump for returning ink not ejected from the recording unit to the tank, and supplying the ink from the tank to the recording unit The ink path is a first curved portion formed for flowing ink flowing in the direction of gravity in a direction against gravity, and a second curved portion formed for flowing ink flowing in the direction against gravity in the direction of gravity. And a plurality of curved portions.

  ADVANTAGE OF THE INVENTION According to this invention, while ensuring required flow volume and nozzle pressure, the inkjet printer provided with the ink circulation path | route with which the ink flow-down by the impact and the vibration was reduced can be provided.

FIG. 1 is a schematic view showing an ink path and an atmospheric path of the ink jet printer of the present invention. FIG. 2 is a schematic diagram illustrating a first ink path according to the first embodiment. FIG. 3 is a diagram illustrating a meandering state of the first ink path. 4A to 4D are schematic views illustrating the operation of ink in the first ink path of the first embodiment. FIG. 5 is a schematic diagram illustrating a first ink path according to the first embodiment. FIG. 6 is a schematic diagram illustrating a first ink path according to the first embodiment. FIGS. 7A and 7B are schematic views showing the first ink path of the first modification. FIGS. 8A and 8B are schematic views showing the first ink path of the second modification. FIG. 9 is a schematic diagram illustrating a first ink path of a third modification. FIG. 10 is a schematic diagram illustrating a first ink path according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram illustrating an ink path and an atmospheric path of the inkjet printer 1.
Although not shown, the inkjet printer 1 includes a supply unit that supplies a recording medium, a conveyance mechanism that conveys the supplied recording medium, an unloading unit that unloads an image-recorded recording medium, and a cleaning that cleans the ink head. And a control unit that controls the entire printer including the ink jet control and the ink discharge control.

  The inkjet printer 1 records an image on a recording medium using, for example, four colors of ink of cyan (C), magenta (M), yellow (Y), and black (K). Although FIG. 1 shows only an ink path related to a representative color ink, this printer has a similar ink path for each ink color.

  The ink jet printer 1 can be broadly divided into an ink circulation path (ink circulation part) 6, an ink replenishment part 11 for replenishing ink to the ink circulation part 6, and a waste liquid part 12 for containing unnecessary ink and overflowed ink. A pressure adjusting unit 18 that adjusts the pressure in the ink circulating unit 6, a first atmosphere opening unit 60 that allows the inside of the first tank 4 in the ink circulating unit 6 to communicate with or be blocked from the atmosphere, and ink circulation. The second tank 5 in the unit 6 has a second atmosphere opening part 61 that allows the inside of the second tank 5 to communicate with or be blocked from the atmosphere.

  Note that when four colors of ink are used as described above, the ink jet printer 1 includes four independent ink circulation units 6. However, in this embodiment, the waste liquid part 12, the pressure adjusting part 18, a part of the first atmosphere opening part 60, and a part of the second atmosphere opening part 61 are shared by all colors.

First, the ink replenishing unit 11 will be described.
The ink replenishment unit 11 includes an ink cartridge tray 22, a joint unit 23, a cartridge determination unit 24, and a replenishment valve 25.

The ink cartridge tray 22 holds the ink cartridge 21 in a detachable manner. The ink cartridge tray 22 is provided with a joint portion 23.
The joint portion 23 is connected to the ink supply port of the ink cartridge 21 when the ink cartridge 21 is held at a predetermined position in the ink cartridge tray 22. The joint portion 23 is connected to the second tank 5 by the ink path 10.

The cartridge determination unit 24 prevents erroneous mounting of the ink cartridge 21 and detects the remaining amount of ink.
The refill valve 25 is provided in the ink path 10 that connects the joint portion 23 and the second tank 5. The replenishing valve 25 is controlled to open and close based on the amount of ink in the ink circulation unit 6. That is, as will be described later, when the amount of ink in the ink circulation unit 6 is equal to or less than a predetermined amount, the replenishing valve 25 is opened and ink is supplied to the second tank 5, and the amount of ink in the ink circulation unit 6 is limited. In the case of a fixed amount or more, the supply valve 25 is closed.

Next, the waste liquid part 12 will be described.
The waste liquid unit 12 includes a waste liquid tank 26, a waste liquid tank tray 27 on which the waste liquid tank 26 is placed, a waste ink amount detection unit 28, a tank attachment detection unit 29, and an overflow tank 30.

  The waste liquid tank tray 27 is provided at a position lower than the lowermost part of the ink circulation unit 6, and the waste liquid tank 26 is disposed thereon. The waste ink amount detection unit 28 detects the amount of ink accommodated in the waste liquid tank 26 by reading the difference in the weight of the waste liquid tank 26 and the height of the ink liquid surface in the waste liquid tank 26. The tank mounting detection unit 29 detects whether or not the waste liquid tank 26 is mounted by optical detection.

The overflow tank 30 collects the ink overflowing from the ink circulation unit 6 and flows it into the waste liquid tank 26. Therefore, the waste liquid tank 26 and the overflow tank 30 are connected by a waste liquid path 31. The overflow tank 30 has a tray shape whose upper surface is open, and is in a state of communicating with the atmosphere. The overflow tank 30 is provided below the pump 34 so as to receive all of the ink even if the later-described pump 34 is damaged and the ink leaks.
Furthermore, a first atmosphere release portion 60 and a second atmosphere release portion 61 are connected to the overflow tank 30.

  Here, the first atmosphere release unit 60 includes the atmosphere path 13, the first tank common air chamber 14, and the atmosphere release valve 32.

  The atmospheric path 13 has one end connected to the atmospheric port 4 c of the first tank 4 and the other end connected to the overflow tank 30. A first tank common air chamber 14 and an air release valve 32 are provided in the air path 13. More specifically, in the atmosphere path 13, the first tank common air chamber 14 is disposed so as to be closer to the first tank 4 than the atmosphere release valve 32. The first tank common air chamber 14 is also connected to the first tanks of other colors, and the first tank common air chamber 14 and the atmosphere release valve 32 are shared by all colors.

  Since the overflow tank 30 communicates with the atmosphere, the first atmosphere opening section 60 configured as described above opens and closes (opens / blocks) the atmosphere opening valve 32 to open the first tank common air chamber 14. Communicate or block the interior with the atmosphere. In other words, since the first tanks 4 for all colors are connected to the first tank common air chamber 14, they can be simultaneously communicated with or blocked from the atmosphere by opening and closing the atmosphere release valve 32.

  In addition, even if the first atmosphere opening unit 60 overflows ink from the first tank 4 when an abnormality occurs in the printer, the overflowed ink can flow to the overflow tank 30. In the present embodiment, the first tank common air chamber 14 is provided, but the first tank common air chamber 14 is not an essential component. That is, it is only necessary that the first atmosphere opening unit 60 can be in a state where the inside of the first tank 4 communicates with the atmosphere (atmosphere release state) or a state where it is blocked from the atmosphere (sealed state).

  The second atmosphere opening unit 61 includes an atmosphere path 15, a second tank common air chamber 16, and an atmosphere opening valve 33.

  The atmospheric path 15 has one end connected to the atmospheric port 5 c of the second tank 5 and the other end connected to the overflow tank 30. A second tank common air chamber 16 and an air release valve 33 are provided in the air path 15. More specifically, in the atmosphere path 15, the second tank common air chamber 16 is arranged so as to be closer to the second tank 5 than the atmosphere release valve 33. The second tank common air chamber 16 is also connected to a second tank of another color, and the second tank common air chamber 16 and the atmosphere release valve 33 are shared by all colors.

  Since the overflow tank 30 communicates with the atmosphere, the second atmosphere opening portion 61 configured in this way opens and closes (opens / blocks) the atmosphere opening valve 33 to open the second tank common air chamber 16. Communicate or block the interior with the atmosphere. That is, since the second tanks 5 for all colors are connected to the second tank common air chamber 16, they can be simultaneously communicated with or blocked from the atmosphere by opening and closing the atmosphere release valve 33.

  Further, even if the second atmosphere release unit 61 overflows ink from the second tank 5 when an abnormality occurs in the printer, the overflowed ink can flow to the overflow tank 30. In the present embodiment, the second tank common air chamber 16 is provided, but the second tank common air chamber 16 is not an essential component. That is, it is only necessary that the second atmosphere opening unit 61 can be brought into a state where the inside of the second tank 5 communicates with the atmosphere (atmosphere release state) or a state where the second tank 5 is blocked from the atmosphere (sealed state).

Next, the ink circulation unit 6 will be described.
The ink circulation unit 6 includes an image recording unit 3, a first tank 4, a second tank 5, a pump 34, a heat exchanger 36, and a filter 37. The nozzle surface 50 in which the nozzle holes of the ink head 2 are formed, the first ink liquid surface 51 in the first tank 4 and the second ink liquid surface 52 in the second tank 5 are in the height direction (gravity The first ink liquid surface 51, the nozzle surface 50, and the second ink liquid surface 52 are arranged in order from a high position to a low position in the direction). The ink circulation unit 6 starts from the first tank 4 to the ink distributor 19, each ink head 2, the ink collector 20, the second tank 5, the pump 34, the one-way valve 35, and the heat exchanger during ink circulation. Each component is connected by an ink path (first to third tubes 7 to 9) so that ink flows in the order of 36 and the filter 37 and returns to the first tank 4.

Each component of the ink circulation unit 6 will be described in detail.
The first tank 4 is disposed above the ink head 2 in the gravity direction. The first tank 4 is provided with an ink inlet port 4a, an ink outlet port 4b, and an atmospheric port 4c.

The ink inlet port 4 a is connected to the filter 37 via the third tube 9, and allows the ink that has passed through the filter 37 to flow into the first tank 4.
The ink outlet port 4 b is connected to the first tube 7 serving as the first path, and causes the ink flowing out from the first tank 4 to flow into the ink distributor 19.
The atmospheric port 4 c is connected to the first tank common air chamber 14 via the atmospheric path 13.

A first liquid level detector 38 is provided in the first tank 4 in order to keep the ink level 51 in the tank at a predetermined height.
The first liquid level detection unit 38 is supported by a float member 38a supported by a support shaft 38d so as to rotate in the first tank 4 in accordance with the height of the ink liquid level, and the float member 38a. The magnet 38c and the liquid level position sensor 38b are attached.

  The liquid level position sensor 38b is, for example, a magnetic sensor, and detects a magnet 38c attached to the float member 38a. Thus, the liquid level position sensor 38b detects the position of the float member 38a, that is, the height of the ink level 51 in the first tank 4. As described above, the first liquid level detection unit 38 is provided to maintain the ink amount stored in the first tank 4 at a predetermined amount.

Here, FIG. 2 is a schematic diagram showing the first tube 7 as a first path connecting the first tank 4 and the image recording unit 3.
The first tube 7 is meandering (curved) so as to have at least two peak portions 101 and 103 and valley portions 102 and 104. In other words, the first tube 7 flows in the direction against the gravity, and the valleys 102 and 104 as the first curved portion formed to flow the ink flowing in the direction of gravity in the direction against the gravity. It meanders so as to have peak portions 101 and 103 as second curved portions formed to flow ink in the direction of gravity.

  In the first tube 7, the lower side of the inner surface of the peak portions 101 and 103 is higher in the gravity direction than the upper inner surface of the valley portions 102 and 104. That is, as shown in FIG. 3, for example, in the first tube 7, the height A of the lowest point of the peak portion 101 is positioned higher than the height B of the highest point of the valley portion 102 in the gravity direction. Meander.

  In the present embodiment, the first tube 7 meanders between the first tank 4 and the image recording unit 3. That is, the peaks 101 and 103 are formed so as to be lower in the direction of gravity than the first tank 4, and the valleys 102 and 104 are formed so as to be higher in the direction of gravity than the image recording unit 3. In the present embodiment, the amount of ink supplied to the image recording unit 3 via the first tube 7 is set to exceed the amount of ink ejected by the image recording unit 3. In order to prevent the flow resistance from increasing while securing such a flow rate, and to allow replacement of air and ink as described later, the inner diameter of the first tube 7 is preferably φ4 or more. .

  With such a configuration, when the ink circulation unit 6 is filled with ink, as will be described later, even if air flows into the ink in the first tube 7, the air layer formed in the peak portion is buffered. The air layer does not communicate between the adjacent peak and valley.

  The first tube 7 supplies the ink in the first tank 4 to the image recording unit 3.

  The image recording unit 3 includes a plurality of ink heads 2, an ink distributor 19 that distributes ink to these ink heads 2, and an ink collector 20 that recovers ink from these ink heads 2.

The ink distributor 19 is connected to a plurality of ink heads 2. The ink distributor 19 is connected to the first tank 4 via the first tube 7.
The ink collector 20 is connected to a plurality of ink heads 2. Further, the ink collector 20 is connected to the second tank 5 through a second tube.

  As described above, the amount of ink flowing into the ink head 2 is set to exceed the amount of ink ejected from the nozzles of the ink head 2. For this reason, the ink that has not been ejected from the nozzles is once collected by the ink collector 20 and flows out to the second tank 5 via the second tube 8.

  The ink head 2 is maintained at a negative pressure suitable for an image recording operation (in this embodiment, a gauge pressure of about −1 kPa) during ink circulation. As a result, a meniscus recessed on the spherical surface is formed inside the nozzle. The ink head 2 ejects ink based on the image signal input from the external device, and records an image on a recording medium conveyed by the conveyance unit.

  Note that the image recording unit 3 of the present embodiment uses short ink heads 2 that are less than the width of the recording medium (the direction orthogonal to the transport direction), and these ink heads 2 are arranged in the width direction of the recording medium, for example, staggered. Are arranged in a staggered manner (staggered) and fixed to a frame or the like to constitute a line head. Of course, the image recording unit 3 is not limited to the line type (line head), but may be a serial type (serial head) that performs recording while scanning the recording medium.

  The second tank 5 is disposed below the ink head 2 in the direction of gravity. In the second tank 5, an ink inlet port 5 a through which ink flows from the ink collector 20 through the second tube 8, an ink outlet port 5 b for sending ink to the third tube 9, and an atmospheric path 15 Thus, an atmospheric port 5c connected to the second tank common air chamber 16 and a supply port 5d connected to the joint portion 23 (ink cartridge 21) via the supply valve 25 by the ink path 10 are provided. ing. The ink cartridge 21 is disposed above the second tank 5 in the direction of gravity, and replenishes ink into the second tank 5 by opening the refill valve 25.

  In the present embodiment, the ink is supplied from the ink cartridge 21 to the second tank 5 by opening the supply valve 25. However, the present invention is not limited to such a configuration, and the ink cartridge 21 is used. It is only necessary that the ink can be fed from the first to the second tank 5. Therefore, for example, the ink may be fed by a pump or the like instead of the refill valve 25.

  Further, in the second tank 5, a second liquid level detector 39 is provided in the same manner as the first tank 4 in order to keep the ink liquid level 52 at a predetermined height. The second liquid level detection unit 39 is supported by a float member 39a supported by a support shaft 39d so as to rotate in the second tank 5 in accordance with the height of the ink liquid level, and the float member 39a. It is comprised by the attached magnet 39c and the liquid level position sensor 39b.

  The liquid level position sensor 39b is a magnetic sensor, for example, and detects a magnet 39c attached to the float member 39a. Accordingly, the liquid level position sensor 39b detects the position of the float member 39a, that is, the height of the ink level 52 in the second tank 5. As described above, the second liquid level detection unit 39 is provided in order to maintain the ink amount stored in the second tank 5 at a predetermined amount.

  That is, the opening / closing operation of the replenishing valve 25 described above is performed according to the detection result of the second liquid level detector 39 so as to maintain the height of the second ink liquid level 52 within a desired range. Specifically, when the second liquid level detection unit 39 is ON, it is determined that the amount of ink in the second tank 5 is sufficient, and the replenishing valve 25 is closed. Conversely, when the second liquid level detector 39 is OFF, it is determined that the amount of ink in the second tank 5 is insufficient, and the refill valve 25 is opened. By this operation, ink is supplied from the ink cartridge 21 into the second tank 5, and the liquid level of the second tank 5 is maintained in a desired range.

  In particular, when the ink in the ink cartridge 21 is consumed and emptied, the second tank 5 is not replenished with ink, and the second liquid level detection unit 39 is kept in the OFF state. When the second liquid level detection unit 39 is OFF for a predetermined time, it is determined that the ink cartridge 21 is empty, and a notification for prompting replacement of the ink cartridge (display on a display unit (not shown), warning sound, etc.) is made.

  The pump 34 can be, for example, an electromagnetic piston pump. The pump 34 is driven and stopped according to the detection result of the first liquid level detection unit 38 so as to maintain the height of the ink liquid level 51 within a desired range. Specifically, when the first liquid level detection unit 38 is ON, it is determined that the amount of ink in the first tank 4 is sufficient, and the pump 34 is stopped. Conversely, when the first liquid level detector 38 is OFF, it is determined that the amount of ink in the first tank 4 is insufficient, and the pump 34 is driven. By this operation, ink is pumped from the second tank 5 to the first tank 4, and the liquid level height of the first tank 4 is maintained in a desired range.

  In the present embodiment, the liquid feeding capacity of the pump 34 is set so that a larger amount of ink can be fed to the first tank 4 than the amount of ink flowing into the second tank 5. This is to prevent the ink in the second tank 5 from overflowing. That is, by increasing the ink flow rate that can be pumped up when the pump 34 is driven, the ink does not overflow from the second tank 5 rather than the ink flow rate that flows into the second tank 5 in a normal use state. I am doing so.

  In this embodiment, an electromagnetic piston pump is used as the pump 34. However, for example, a diaphragm pump can be used as long as it has the ability to feed more ink than the amount of ink flowing into the second tank 5. A gear pump, a tube pump, a rotary pump, or a spiral pump may be used.

  A one-way valve (not shown) is connected to the downstream side of the pump 34 (the liquid feed side to the first tank 4), and the ink level 51 of the first tank 4 and the second tank 5 Back flow of ink (back flow from the first tank 4 to the second tank 5) due to the height difference from the ink liquid level 52 is prevented. That is, when the pump 34 is stopped, the ink tends to flow backward from the first tank 4 to the second tank 5 due to the water head difference, and this flow is prevented.

  Further, as described above, the liquid feeding capacity of the pump 34 is set so that a larger amount of ink can be fed from the first tank 4 via the ink head 2 and into the second tank 5. Therefore, the pump 34 performs an intermittent operation during the ink circulation operation.

  The heat exchanger 36 heats and / or cools the ink flowing in the ink circulation unit 6. That is, the heat exchanger 36 controls the temperature of the ink flowing in the ink circulation unit 6 to a desired temperature at which an image can be recorded. A temperature sensor 40 is disposed in each ink head 2 or in the ink flow path in the vicinity thereof in order to control the heat exchanger 36.

  The filter 37 is provided in order to remove foreign matters contained in the ink supplied to the ink head 2 and eliminate a recording defect due to clogging of nozzle holes formed in the ink head 2.

Next, the pressure adjusting unit 18 will be described.
The pressure adjusting unit 18 includes a bellows 41, a weight 42, and a bellows lifting mechanism 43.

  The bellows 41 is connected to the second tank common air chamber 16 by the atmospheric path 17. A weight 42 is attached to the bellows 41. The weight 42 is raised and lowered by a bellows lifting mechanism 43. That is, when the bellows lifting mechanism 43 is raised, the bellows 41 is contracted, and when the bellows lifting mechanism 43 is lowered, the bellows 41 is expanded. In addition, let the position of the bellows raising / lowering mechanism 43 in the state which shortened the bellows 41 be a standby position. Further, the position of the bellows lifting mechanism 43 in a state where the bellows 41 is extended is set as a negative pressure generation position.

  Here, when the atmosphere release valve 33 is closed, the air portion of the second tank 5, the second tank common air chamber 16, and the inside of the bellows 41 are in communication with each other and are closed from the outside. When the bellows 41 is expanded and contracted in this state, the volume of the closed space increases or decreases. As a result, the pressure in the second tank 5 for all colors changes simultaneously.

  That is, when the bellows lifting mechanism 43 is moved from the standby position to the negative pressure generation position with the atmosphere release valve 33 closed, the bellows 41 is pulled downward by the weight of the weight 42, and the volume of the closed space is increased. To increase. Thereby, a negative pressure of a magnitude that balances the gravity applied to the weight 42 is applied in the second tank common air chamber 16.

  The second tank common air chamber 16 communicates with the second tank 5. Therefore, the same negative pressure as the second tank common air chamber 16 is applied to the second tank 5. Further, since the second tank 5 communicates with the ink head 2 via the second tube 8, the same negative pressure is applied to the ink head 2. The negative pressure is set so that a pressure suitable for recording (for example, the nozzle pressure is about −1 kPa in the ink circulation state) is applied to the inside of the ink head 2. A meniscus is formed in the nozzle hole by this pressure.

Next, the operation of each component during image recording (when ink is circulated) and during standby (when ink is not circulated) will be briefly described.
First, the atmosphere release valve 32 is opened, and the inside of the first tank 4 is opened to the atmosphere. At the same time, the air release valve 33 is closed, and the pressure in the second tank 5 is set to a predetermined negative pressure state by the pressure adjusting unit 18. In such a state, the inkjet printer 1 controls the operation of the pump 34 and the replenishment valve 25 according to the amount of ink in the first tank 4 and the second tank 5 to circulate the ink. That is, as described above, the ink flows in the order of the first tank 4, the ink distributor 19, the ink head 2, the ink collector 20, the second tank 5, the pump 34, the heat exchanger 36, and the filter 37. The ink circulates back to the tank 4 of the first tank.

  Further, when the inkjet printer 1 is on standby, the atmosphere release valve 32 is closed, the first tank 4 is shut off from the atmosphere, the atmosphere release valve 33 is opened, and the second tank 5 is opened to the atmosphere. .

  At this time, since the second tank 5 is arranged below the ink head 2 in the gravity direction as described above, a meniscus is formed in the nozzles of the ink head 2 due to a water head difference. That is, ink does not spill from the ink head 2 during standby.

  In the ink circulation unit 6 configured as described above, when the meniscus is destroyed by impact or vibration during transportation or replacement of the recording head, and air flows into the ink circulation unit 6 from the nozzles of the ink head 2, the first circulation is performed. The balance which was balanced by the head difference between the tank 4 and the second tank 5 is lost. The air flowing from the nozzles of the ink head 2 tends to move to the first tank 4 by the negative pressure of the first tank 4 while replacing the ink in the first tube 7. Finally, the ink stored in the first tank 4 flows down toward the second tank 5.

  Therefore, even if air flows in from the nozzles of the ink head 2, the amount of ink flowing into the second tank must be regulated to a predetermined flow rate or less so that the ink does not overflow from the second tank 5. There is.

  In this embodiment, the case where the meniscus formed in the nozzles of the ink head 2 is destroyed by vibration or impact during transportation, installation, or transfer of the apparatus is described with reference to FIGS. explain.

  When the meniscus formed in the nozzle of the ink head 2 is destroyed, the ink in the first tube 7 gradually falls from the nozzle, and the air replaced with this ink as shown in FIG. Flows into the downstream side of the peak portion 101. And as shown in FIG.4 (b), this air flows in toward the trough part 102 over the peak part 101 by vibration. Further, the air passes through the valley 102 and reaches the peak 103 and replaces the ink of the peak 103. At this time, the ink at the peak portion 103 falls downstream. Thus, as shown in FIG. 4C, the air stays at the peak portion 103 by buoyancy. When air accumulates to some extent in the mountain portion 103, this air forms an air layer. Finally, as shown in FIG. 4D, this air layer becomes a buffer and suppresses vibration of the ink. Accordingly, air does not flow into the ink, and the ink and air are not replaced any more. That is, the ink in the first tank 4 does not fall to the ink head 2 side (downstream side).

  In the second tank 5, an allowable portion is provided in advance in consideration of the amount of ink that falls while being replaced with air in the first tube 7. Specifically, in the present embodiment, at least the ink collector 20 and an allowable portion that does not overflow even if the ink in the second tube 8 flows down are provided.

  As described above, the first tube 7 connecting the first tank 4 and the image recording unit 3 meanders so as to have a peak portion and a valley portion, so that the ink head of the image recording portion 3 is provided. The air that has flowed into the nozzle provided in 2 reaches the peak 101 while replacing the ink in the first tube 7, and further reaches the peak 103 through the valley 102 to form an air layer. . This air layer acts as a buffer against vibration and the like, and no further ink movement occurs. Thus, the amount of ink that flows down due to impact or vibration can be reduced.

  When the vibration of the ink is large, it is conceivable that air further flows over the peak portion 103. In this case, as shown in FIG. 5, if three or more peaks are provided, the above-described operations of FIGS. 4A to 4D occur between the peaks 103 and 105 on the upstream side. As shown in FIG. 6, an air layer is also formed on the peak portion 105. If the number of air layers increases due to the increase in the number of ridges, the buffer effect by the air layers also increases, and ink vibration can be further suppressed. Thereby, even when the vibration is large, the ink in the first tank 4 does not fall to the ink head 2 side (downstream side). Thus, the ink in the first tank 4 does not flow to the second tank 5 and the ink in the second tank 5 does not overflow.

  Further, as shown in FIG. 7A, when the first tube 7 is meandered, the valleys 102, 104, 106 are set lower than the nozzle surface height of the image recording unit 3. Thereby, more air layers can be secured in the valleys of the first tube 7 and ink vibration can be prevented. Further, as shown in FIG. 7B, when meandering the first tube 7, at least one valley may be set lower than the nozzle surface height of the image recording unit 3. In this case, if the valley that is lower than the nozzle surface height of the image recording unit 3 is close to the image recording unit 3, the amount of ink that falls is small, and therefore the valley that is closest to the image recording unit 3 in FIG. 102 is set lower than the height of the ink surface of the image recording unit 3.

  Further, as shown in FIG. 8A, when the first tube 7 is meandered, the peak portions 101, 103, and 105 are made higher than the ink liquid level in the first tank 4. Thereby, more air layers can be secured in the peak portion of the first tube 7 and ink vibration can be prevented. Further, as shown in FIG. 8B, when meandering the first tube 7, at least one peak may be made higher than the ink liquid level in the first tank 4. If the crest that is higher than the ink liquid level in the first tank 4 is close to the image recording unit 3, the ink is unlikely to fall off. Therefore, in FIG. 8B, the crest 101 that is closest to the image recording unit 3 is The height of the ink level in one tank 4 is set higher.

  Moreover, as shown in FIG. 9, by making the 1st tube 7 into a spiral shape, compared with the 1st tube 7 to meander, it can arrange | position more compactly.

FIG. 10 is a schematic view showing the first tube 7 of the second embodiment of the present invention.
In FIG. 10, a resin joint 110 having an ink path having at least two crests and troughs therein is provided as a first path between the first tank 4 and the image recording unit 3. ing. With such a configuration, meandering with a curvature that causes buckling in the tube is possible, and a more compact design is possible.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, A various improvement and change are possible within the range which does not deviate from the summary of this invention.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Ink head, 3 ... Image recording part, 4 ... 1st tank, 5 ... 2nd tank, 6 ... Ink circulation path, 7 ... 1st tube, 8 ... 2nd tube, DESCRIPTION OF SYMBOLS 9 ... 3rd tube, 10 ... Ink path, 11 ... Ink replenishment part, 12 ... Waste liquid part, 13 ... Atmospheric path, 14 ... First tank common air chamber, 15 ... Atmospheric path, 16 ... Common to 2nd tank Air chamber 17 ... Atmospheric path 18 ... Pressure adjusting unit 19 ... Ink distributor 20 ... Ink collector 21 ... Ink cartridge 22 ... Ink cartridge tray 23 ... Joint unit 24 ... Cartridge judgment unit 25 ... Replenishment valve, 26 ... Waste liquid tank, 27 ... Waste liquid tank tray, 28 ... Waste ink amount detection unit, 29 ... Tank installation detection unit, 30 ... Overflow tank, 31 ... Waste liquid path, 32, 33 ... Air release valve 34 ... pump, 36 ... heat exchanger, 37 ... filter, 38 ... first liquid level detection unit, 39 ... second liquid level detection unit, 40 ... temperature sensor, 41 ... bellows, 42 ... weight, 43 ... bellows Elevating mechanism, 51 ... first ink level, 52 ... second ink level, 60 ... first atmosphere opening part, 61 ... second atmosphere opening part, 101, 103, 105 ... mountain part, 102, 104, 106 ... trough, 110 ... joint.

Claims (7)

A recording unit having an ink head with a nozzle surface on which a plurality of nozzles are formed;
A first tank that is disposed above the nozzle surface in the direction of gravity and stores ink to be supplied to the recording unit;
A second tank disposed below the nozzle surface in the direction of gravity and collecting and storing ink from the recording unit;
A first tube connecting the recording unit and the first tank;
A second tube connecting the recording unit and the second tank;
A third tube connecting the first tank and the second tank;
An ink circulation path comprising a pump for pumping ink in the second tank to the first tank,
The ink jet printer according to claim 1, wherein the first tube is meandered in a gravity direction.   2. The ink jet printer according to claim 1, wherein the meandering of the first tube has at least two crests and troughs. When the ink circulation path is filled with ink,
When the air flows into the ink in the first tube, the height of the lowest point of the peak is the highest point of the valley so that the air does not communicate between adjacent peaks and valleys. 3. The ink jet printer according to claim 2, wherein the ink jet printer is positioned above the height of.   The ink jet printer according to claim 3, wherein the trough is located below the nozzle surface in the direction of gravity.   4. The ink jet printer according to claim 3, wherein the peak portion is positioned above the ink liquid level in the first tank in the direction of gravity.   2. The ink jet printer according to claim 1, wherein the first tube is a resin joint having an ink path having at least two crests and troughs therein. A recording unit having an ink head in which a plurality of nozzles for ejecting ink are formed, a tank that is disposed above the nozzle surface in which the plurality of nozzles are formed in the gravitational direction, and stores ink to be supplied to the recording unit; An ink jet printer comprising an ink circulation unit having at least a pump for returning ink that has not been ejected by the recording unit to the tank,
The ink path for supplying the ink from the tank to the recording unit includes a first curved portion formed to flow ink flowing in the direction of gravity in a direction against gravity, and ink flowing in the direction against gravity. An inkjet printer comprising a plurality of second curved portions formed to flow in the direction of gravity.

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