JP3991401B2 - Inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an ink jet printer having a nozzle head having nozzles for ejecting ink onto a recording medium, and more specifically, an ink jet printer capable of purging an ink ejection path by forcibly feeding ink into the nozzle head. About.
[0002]
[Prior art]
  Conventionally, in an ink jet printer having a nozzle head having a nozzle for ejecting ink onto a recording medium, there is a possibility that bubbles or dust may be mixed in the ink in the ejection path or the ink in the ejection path may be solidified. is there. In such a case, ink ejection failure may occur, and it may be difficult to form an image according to the drive signal.
[0003]
  Therefore, in recent years, an ink jet printer having a maintenance means for purifying the ejection path (hereinafter also referred to as maintenance) has been developed. As this maintenance means, for example, purge forcibly ejecting ink in the ejection path together with bubbles and dust (also referred to as purging), wiping to wipe the nozzle surface and remove ink and dust around the nozzle, Something that performs etc. is considered. When an ejection failure occurs, the ink ejection failure can be eliminated by purifying the ejection path with the maintenance means.
[0004]
  However, when maintenance is performed by purging, a large amount of ink must be forcibly ejected in order to completely remove bubbles and the like in the ejection path, resulting in wasted ink. In view of this, it has been proposed that an ink tank for storing ink is constituted by a main chamber and a sub chamber, and the waste of ink accompanying purging is suppressed as follows.
[0005]
  For example, the ink jet head illustrated in the schematic diagram of FIG. 13 includes a main chamber 911 and a sub chamber 913 that store ink as the ink tank 910. The nozzle head 931 that ejects ink onto the recording medium includes a large number of nozzles 932, and ink is supplied from the main chamber 911 through the forward path 935. The nozzle head 931 and the sub chamber 913 are connected via a return path 937.
[0006]
  The nozzle head 931 includes a piezoelectric conversion element 938 corresponding to each nozzle 932, and ink in the nozzle 932 is ejected according to a volume change of the piezoelectric conversion element 938. During normal printing, the amount of ink consumed by this ink ejection is supplied from the main chamber 911 via the forward path 935.
[0007]
  When performing maintenance by purging, the ink stored in the main chamber 911 is pressurized by a pump (not shown) or the like, and the ink is forcibly sent to the nozzle head 931 via the forward path 935. Then, the ink sent to the nozzle head 931 is divided into a path for discharging from the nozzle 932 and a path toward the sub chamber 913 via the return path 937. The ink flow rate ratio in these two paths is determined according to the flow path resistance between the nozzle 932 and the return path 937.
[0008]
  When purging is performed in this way, the amount of ink discharged outside the nozzle 932 may be an ink amount sufficient to discharge bubbles or the like in the nozzle 932. The remaining ink that is forcibly sent to the nozzle head 931 is sent to the sub chamber 913 via the return path 937. By this ink, ink containing bubbles in the forward path 935, the return path 937, and the vicinity of the branch point of the nozzle 932 is replaced with clean ink. Further, the ink stored in the sub chamber 913 can be sent back to the main chamber 911 for reuse after separating bubbles and the like.
[0009]
  In the ink jet head configured as described above, the ink discharged to the outside by the purge can be suppressed to the minimum amount necessary for the purification in the nozzle 932, and the ink used for the purification of the other ejection paths can be reused. It becomes possible. Therefore, waste of ink can be suppressed.
[0010]
[Problems to be solved by the invention]
  However, the flow path resistance between the nozzle 932 and the return path 937 varies depending on the amount of bubbles or the like contained in the ink, the position where the bubbles or the like exist, and the like. In the ink jet head of FIG. 13, the flow rate resistance defines the ink flow ratio between the path discharged from the nozzle 932 and the path toward the sub chamber 913 via the return path 937. Some variation occurred. Therefore, in order to reliably purify the ink ejection path by purging, it is necessary to pressurize the ink in the main chamber 911 at a high pressure or pressurize it for a long period of time to compensate for the fluctuation in the flow rate ratio. there were. For this reason, there is a limit in suppressing the waste of ink accompanying the purge.
[0011]
  Therefore, the present invention providesBy purgingReliable purification of the ink ejection pathIn addition, the waste of ink associated with the purge can be further suppressed.It was made for the purpose of providing an inkjet printer that can be used.
[0012]
[Means for Solving the Problems and Effects of the Invention]
  In order to achieve the above object, an invention according to claim 1 is directed to a main chamber for storing ink, a sub chamber connected to the main chamber through a communication path, and an ink stored in the main chamber. A nozzle head having nozzles for jetting on a recording medium; an outward path for supplying ink from the main chamber to the nozzle head; a return path for returning ink from the nozzle head to the sub chamber; and the main chamber Supply stored ink to the outbound pathAnd purge means for purging, valve means for opening and closing the communication path, and whether the communication path is opened or closed by the valve means. A valve control means for switching;An inlet hole formed in the sub chamber and into which ink from the return path flows is allowed to allow ink to flow from the return path to the sub chamber and to prevent ink from flowing from the sub chamber to the return path. One-way valve means;A sealing means capable of sealing the opening of the nozzle when the purge means performs a purge; and a switching means for switching whether or not the sealing by the sealing means is performed when the purge means performs a purge. The flow path resistance of the entire nozzle is smaller than the flow path resistance of the return path, the communication path is closed by the valve control means, and the sealing means is sealed by the switching means. The purge means performs purging in the performed state, and then the purge means is purged in a state where the communication path is closed by the valve control means and the seal is released by the switching means.It is characterized by comprising.
[0013]
  In the present invention configured as described above,By purging meansFrom the main roomOn the wayThe supplied ink is divided into a path that is supplied to the nozzle head via the forward path and is discharged to the outside from the nozzle, and a path that is returned to the sub chamber via the return path. Since the one-way valve means is provided, even if ink containing bubbles or the like is stored in the sub chamber, the ink does not flow into the ink ejection path via the return path, so that the ink ejection path can be reliably established. It can be purified.
  Also,The purge means is purged in a state where the communication path is closed by the valve control means, and the sealing means is sealed by the switching means, and then the communication path is closed by the valve control means, and Since purge is performed by the purge means in a state where the sealing is released by the switching means,FormerIn the purge procedure,All of the supplied ink is returned to the sub chamber through the return path, and the ink containing bubbles in the forward path and the return path is replaced with clean ink that does not include bubbles.
  Followed by the latterPurge processThenOutward trip by purge meansThe supplied ink is also sent to a path discharged from the nozzle. At this time, the ink in the forward path and the return path has already been replaced with clean ink. For this reason, the latterPurge processThen, even if the minimum amount of ink necessary to discharge only the bubbles in the nozzle is sent, the entire ejection path can be sufficiently purified..
[0014]
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a basic configuration of an ink jet printer to which the present invention is applied. The ink jet printer according to the present embodiment is a so-called hot melt ink jet printer that heats and melts solid ink.
[0024]
  As shown in FIG. 1, the head (inkjet head) 1 of the present inkjet printer is mounted on a carriage 3 (see FIG. 10) and is configured to be movable along a guide shaft 5. The head 1 performs printing by ejecting ink onto a recording sheet (not shown) as a recording medium conveyed in the vicinity of the left side of the movement range (left side in FIG. 1). Alternatively, it moves to a purging position near the right end of the guide shaft 5 at a predetermined timing and receives a maintenance operation described later. The carriage 3 is a known one that is connected to the carriage motor 8 via the belt 9 and moves along the guide shaft 5 in accordance with the rotation of the carriage motor 8.
[0025]
  The frame 100 that supports the head 1 via the guide shaft 5 has a guide surface 101 that guides the recording paper on its upper surface, and conveying rollers 103 and 105 are disposed thereon. Pulleys 107 and 109 are coaxially fixed to the transport rollers 103 and 105, and the driving force of the transport motor 111 is transmitted to the pulleys 107 and 109 via the belt 113. Therefore, the recording paper can be conveyed along the guide surface 101 in a direction orthogonal to the guide shaft 5. In the purging position, a rubber pad 115 as a sealing means is disposed at a position facing the nozzle surface 36 (FIG. 4) of the head 1, and the nozzle surface is driven by a pad driving motor 117 (FIG. 8) as a switching means. 36 can be pressed / isolated. Further, in addition to the carriage motor 8 and the transport motor 111 described above, a pump 120 as an ink supply unit is disposed outside the frame 100 on the purging position side.
[0026]
  Next, the configuration of the head 1 will be described with reference to FIGS. 2 is an exploded perspective view of the head 1, FIG. 3 is a top view of the ink tank 10 of the head 1, and FIGS. 4 (a) and 4 (b) are the BB line and CC of FIG. It is a line cut end view. The configuration of the head 1 has been described in detail in Japanese Patent Application No. 8-305325, so please refer to it.
[0027]
  As shown in FIG. 2, the head 1 includes an ink tank 10, a front panel 30, a melting tank 40, a cam 50, and a control panel stage 70. The ink tank 10 has an inclined front surface portion 15 for mounting the front panel 30 and a color output (black, cyan, magenta) capable of storing hot melt ink (hereinafter also simply referred to as ink). , Yellow) four sets of main chambers 11 and sub chambers 13, an ink tank upper lid 19, and an ink tank heater 17 attached to the back surface of the ink tank 10, and further as shown in FIG. In addition, a communication passage 21 opened downward is provided on the back side of the bottom surface of each main chamber 11 and sub chamber 13 of the ink tank 10.
[0028]
  The main chamber 11 is L-shaped when viewed from above, as shown in FIG. 2, and has a main chamber inlet 21 a (FIG. 4B) leading to the communication path 21 and a main channel leading to the front panel 30. A chamber outlet 22a (FIGS. 4A and 2) and a filter 29 (FIG. 4A) are provided. The filter 29 is manufactured by sintering a stainless steel fiber into a paper shape and then pressing it, and each fiber is bent and overlapped in a complicated manner to have a three-dimensional structure passage. (For example, “TOMMY FILEC SS” (registered trademark): manufactured by Yodogawa Paper Co., Ltd.).
[0029]
  The sub chamber 13 includes a sub chamber outlet 21b leading to the communication passage 21, a sub chamber inlet 22b serving as an inlet hole leading to the front panel 30, and the sub chamber outlet 21b and the sub chamber outlet 21b as shown in FIGS. A substantially inverted T-shaped valve opening / closing lever 24 is provided that opens one when one of the chamber inlets 22b is closed.
[0030]
  The valve opening / closing lever 24 is made of an aluminum alloy die cast, and can swing with a lever pedestal 25 provided between the sub chamber outlet 21b and the sub chamber inlet 22b as a support point, as shown in FIG. 4B. It is attached in the state. The valve opening / closing lever 24 includes pressure contact valves 27 and 28, and is normally biased by the leaf spring 26 to keep the pressure contact valve 28 sealing the sub chamber inlet 22b. Here, the pressure contact surface of the pressure contact valve 27 has a spherical shape, and the corresponding edge of the sub chamber outlet 21b has a tapered surface shape. The pressure contact surface of the pressure contact valve 28 has a planar shape, and the corresponding mouth of the sub chamber inlet 22b. The edge has a shape protruding in an annular shape. The pressure contact valves 27 and 28 are made of silicone rubber, and have a Shore hardness of about 40 ° and a heat resistant temperature of about 200 ° C.
[0031]
  Further, a one-way valve 221 shown in FIG. 5 is provided at the sub chamber inlet 22b. The one-way valve 221 is configured such that a disc-like valve body 225 is housed in a cylindrical housing 223 so as to be movable up and down. The housing 223 includes a support plate 227 for receiving the valve body 225 from below, The support plate 227 is formed in a portion facing the valve body 225, and includes a plurality of holes 228 through which ink flows and a stopper 229 that restricts the upward movement of the valve body 225. The stopper 229 prevents the valve body 225 from jumping out of the housing 223 when the ink passing upward through the hole 228 pushes up the valve body 225, and the ink passes through the gap on the valve body 225. Thus, it is formed discontinuously in the circumferential direction of the housing 223 so as to pass through the sub chamber inlet 22b.
[0032]
  In the one-way valve 221, when the ink is about to flow out from the sub chamber 13 to the return path 37, the valve body 225 is pressed against the support plate 227 to inhibit the flow out (see FIG. 5A). When ink is about to flow into the sub chamber 13, the valve body 225 is isolated from the support plate 227 and allowed to flow (see FIG. 5B). In FIG. 5, the flow of ink is indicated by arrows.
[0033]
  As shown in FIG. 2, the ink tank upper lid 19 includes a front panel cover portion 19 a that matches the shape of the front panel 30, a sub chamber cover portion 19 b that covers the sub chamber 13, and an upper end portion 24 a of the valve opening / closing lever 24. A long hole 19c for exposure, an ink inlet 19d for supplying hot melt ink from the melting tank 40 to the sub chamber 13, and air for sending compressed air from the pump 120 (FIG. 1) to each main chamber 11. A chamber 20, a through hole 20 b that opens from the air chamber 20 to the side surface of the ink tank 10, and an air chamber lid 20 a for sealing the air chamber 20 are provided. In addition, the air chamber 20 of the ink tank upper lid 19 includes a through hole 23 that communicates with the main chamber 11 as shown in FIG.
[0034]
  As shown in FIG. 2, the front panel 30 includes four nozzle heads 31 on the front surface, and on the rear surface, forward paths 35 (FIGS. 4A and 6) leading from the main chambers 11 to the nozzle heads 31. ) And return paths 37 (FIGS. 4B and 6) leading from the nozzle heads 31 to the sub chambers 13 are formed. Further, as shown in FIGS. 2 and 4, a lid panel 30a is attached to the back surface of the front panel 30 so as to cover the forward path 35 and the return path 37, and the front panel heater 33 is disposed on the back surface of the lid panel 30a. Is attached. As shown in FIG. 4, an outward passage 35 a from each main chamber 11 to each forward passage 35, an outward passage 35 b from each forward passage 35 to each nozzle head 31, and a backward passage from each nozzle head 31 to each return passage 37. The inlet 37b is provided with a return outlet 37a from each return path 37 to each sub-chamber 13 respectively.
[0035]
  The nozzle head 31 includes a piezoelectric conversion element 38 and ejects ink supplied via the forward path outlet 35 b in accordance with the volume change of the piezoelectric conversion element 38. Further, the ink supplied to the nozzle head 31 can be circulated to the sub chamber 13 via the return path inlet 37 b and the return path 37. That is, as shown by arrows in FIG. 6, the ink reaches the nozzle 32 via the forward path 35, the forward path outlet 35b, and the lower branch point 31a, and further passes through the upper branch point 31b, the return path inlet 37b, and the return path 37. Circulation to the chamber 13 is possible. In addition, the nozzle 32 is configured by arranging 128 fine ejection ports in two rows of 64, and the ink is pressurized by a minute volume change of the piezoelectric conversion element 38, whereby the ink is applied to the recording paper. Spray.
[0036]
  The cam 50 is mounted on the ink tank upper lid 19 so as to be slidable in the left-right direction in FIG. 3, and the vicinity of the contact surface 50 a protrudes from the ink tank upper lid 19 to the right. The cam 50 includes four cam surfaces 50 b, and is biased by a spring 51 spanned between a protrusion 52 provided on the left end of the cam 50 and a protrusion 19 e provided on the ink tank upper lid 19. As a result, the cam surface 50b normally does not touch the upper end 24a of the valve opening / closing lever 24.
[0037]
  As shown in FIG. 2, the melting tank 40 is divided into four rooms for each color of black, cyan, magenta, and yellow, and each room stores ink pellets (not shown) as solid ink. It is in the shape of a box with an open top so that it can. Further, as shown in FIG. 4B, a conduction path 47 for guiding the melted ink to the sub chamber 13 is formed in the lower part of each room of the melting tank 40.
[0038]
  The melting tank 40 includes a heater, and the ink pellets are melted by the heater and supplied to the sub chamber 13 of the ink tank 10 through the conduction path 47. Further, the control panel stage 70 includes a control board and is attached to the top of the head 1.
[0039]
  In the head 1 configured as described above, if the heaters 17 and 33 are driven to hold the ink pellets in a molten state, and the piezoelectric conversion element 38 is driven as described above based on the print data, the ink 1 Can be injected. Further, when moving to the purging position, the following purge can be executed. The purging means that the ink in the front panel 30 and the nozzle head 31 is pressurized from the main chamber 11 side, and the bubbles and dust in the ink that cause non-ejection are collected together with the ink in the nozzle 32. Outside the nozzle surface 36, the inside of the front panel 30 is sent to the sub chamber 13 and is filled with clean ink filtered by the filter 29. Bubbles are mixed in the ink when the temperature of the head 1 is lowered and the ink is solidified when the power is turned off, and the ink is melted when the power is turned on again. There is a case where dust enters through the nozzle 32.
[0040]
  When the head 1 moves to the purging position, the contact surface 50a of the cam 50 is pressed against the frame 100 (see FIG. 3), and a hollow cylindrical cap 55 provided on the frame 100 covers the through hole 20b. Then, the cam 50 slides relatively leftward on the ink tank upper lid 19, and the cam surface 50 b pushes and moves the upper end portion 24 a of the valve opening / closing lever 24 downward in FIG. 3. For this reason, the valve opening / closing lever 24 swings with the lever base 25 as a fulcrum, the pressure contact between the pressure contact valve 28 and the sub chamber inlet 22b is released, and when the swing further proceeds, the pressure contact valve 27 and the sub chamber outlet 21b come into pressure contact. The sub chamber inlet 22b is opened and the sub chamber outlet 21b is sealed.
[0041]
  At this time, since the cap 55 covers the through hole 20b, if compressed air is sent from the pump 120 (FIG. 1) through the pipe 57 connected to the hollow portion of the cap 55, the following is performed. It is possible to extrude bubbles and the like. That is, as schematically shown in FIG. 7, the atmospheric pressure in the main chamber 11 is increased by the feeding of the compressed air. Since the sub chamber outlet 21b is sealed by the pressure contact valve 27 and the sub chamber inlet 22b is opened, the ink 400 stored in the molten state in the main chamber 11 is filtered for bubbles and dust by the filter 29, and the main chamber outlet The nozzle head 31 is reached through 22a, the forward path entrance 35a, the forward path 35, and the forward path exit 35b. Next, it is divided into a path discharged (discharged) from the nozzle 32 and two paths toward the return path inlet 37b side. When the nozzle surface 36 is opened, the respective flow ratios are determined according to the flow path resistance of the forward path 35, the return path 37, and the nozzle 32. The ink 400 that has flowed to the path on the return path inlet 37b side is sent to the sub chamber 13 via the return path 37, the return path outlet 37a, the one-way valve 221, and the sub chamber inlet 22b. As a result, the ink 400 containing bubbles in the forward path 35, the nozzle 32, and the return path 37 is replaced with a clean ink 400.
[0042]
  Thereafter, when the head 1 is moved to the left and the contact surface 50a is separated from the frame 100, the upper end portion 24a of the valve opening / closing lever 24 is not pressed by the cam surface 50b. Then, the valve opening / closing lever 24 swings around the lever base 25 by the urging force of the leaf spring 26, and the sub chamber inlet 22b is sealed and the sub chamber outlet 21b is opened. As a result, the ink 400 forcibly sent into the sub chamber 13 by the purge can be returned to the main chamber 11 from the communication path 21, and the liquid levels of the main chamber 11 and the sub chamber 13 can be made to be at the same level. If the ink 400 in the sub chamber 13 is returned to the main chamber 11 via the return path 37, the forward path 35, and the like, bubbles and dust may remain in the forward path 35 and the like. Is directly returned to the main room 11 via the communication path 21. For this reason, the ejection path (such as the forward path 35) of the ink 400 can be more reliably purified.
[0043]
  The head 1 of the present embodiment is designed such that the flow path resistance of the nozzle 32 as a whole is smaller than the flow path resistance of the return path 37. As a method for setting the channel resistance in this way, for example, the fluidity of ink increases as the temperature increases. Therefore, by setting the temperature of the ink in the nozzle 32 to be high and the temperature of the ink in the return path 37 to be adjusted to be low, the flow path resistance of the nozzle 32 is set low, and the flow path resistance of the return path 37 is set to be high. Can do. Further, the channel resistance may be set according to the size of the channel cross-sectional area and the channel shape. For this reason, when the nozzle surface 36 is opened, most of the ink 400 sent to the forward path 35 is discharged from the nozzle 32 to the outside. Further, as illustrated by an arrow in FIG. 7, if the rubber pad 115 is pressed against the nozzle surface 36, the opening of the nozzle 32 can be sealed to prevent the ink 400 from being discharged from the nozzle 32. In this case, all ink 400 sent to the forward path 35 is circulated through the return path 37. Therefore, as will be described later, if the purge is performed twice by switching the pressure contact / separation of the rubber pad 115, the ink 400 including the bubbles in the forward path 35, the nozzle 32, and the return path 37 is very efficiently converted into a clean ink 400. Can be replaced.
[0044]
  Next, the configuration of the control board of the control panel stage 70 will be described. FIG. 8 is an explanatory diagram schematically showing the configuration of the control board of the control panel stage 70. As shown in FIG. 8, the control board of the control panel stage 70 has a ROM 70 storing a control program, a one-chip type CPU 70a incorporating an input / output port, etc., and a piezoelectric transducer 38 according to print data and the like. Various types such as a head driving circuit 70b for driving, a motor driving circuit 70c for driving various motors such as a carriage motor 8, a conveyance motor 111, a pad driving motor 117, and a pump 120, an ink tank heater 17, a front panel heater 33, and the like. A heater drive circuit 70d for driving the heater, a RAM (not shown), a clock, and the like are mainly configured.
[0045]
  In the control panel stage 70 configured as described above, the CPU 70a executes a maintenance operation by purging at a predetermined timing such as at the time of activation. Next, processing executed by the CPU 70a will be described. FIG. 9 is a flowchart showing a process executed by the CPU 70a at the time of start-up in which the ink tank 10 and the front panel 30 are maintained at a predetermined temperature to prepare for printing. Except for the processes related to heater control (S1 to S7), the CPU 70a also performs the maintenance operation by the same process as described below at the predetermined timing before and after printing and during printing.
[0046]
  When the process is started, first, the head 1 is moved to the high-speed heating position by the carriage motor 8 in S1 (S represents a step: the same applies hereinafter). The ink tank heater 17 and the front panel heater 33 for heating the head 1 are each configured by combining a plurality of heaters. When the head 1 is moved and arranged at this high-speed heating position, all the heaters are connected to the power source. Can be energized. In subsequent S3, the heater driving circuit 70d is controlled in this state, and all the heaters constituting the ink tank heater 17 and the front panel heater 33 are operated to heat the head 1 at high speed.
[0047]
  When the head 1 is heated to some extent by the process of S3, the process proceeds to S5, and only the heater that can be energized in any position of the ink tank heater 17 is energized to keep the ink tank 10 at a predetermined temperature. To do. In subsequent S7, only the heater that can be energized regardless of the position of the head 1 in the front panel heater 33 is energized, and the energized state is controlled to keep the front panel 30 at a predetermined temperature.
[0048]
  Subsequently, when proceeding to S11, the carriage motor 8 is driven via the motor drive circuit 70c, and the head 1 is moved to the above-mentioned purging position. Then, the contact surface 50a of the cam 50 is pressed against the frame 100 (see FIG. 3), and the purge described above can be executed. Therefore, in the subsequent S13, circulation purging is performed in which the pump 120 is driven in a state where the rubber pad 115 is pressed against the nozzle surface 36 via the pad drive motor 117, and the ink 400 is circulated via the return path 37. Further, in the subsequent S15, the pump 120 is driven in a state where the rubber pad 115 is isolated from the nozzle surface 36, and the discharge purging for discharging the ink 400 to the outside from the nozzle 32 is performed. After purging by S13 and S15 is completed, the process proceeds to S17, and the carriage motor 8 is driven to move the head 1 to a predetermined home position (position where the head 1 normally stands by while the printer is operating) to complete the processing. To do.
[0049]
  As described above, in the present ink jet printer, the head 1 is heated at the time of startup to hold the ink 400 in a molten state (S1 to S7), and then the circulation purging (S13) and the discharge purging (S15) are sequentially performed. . The switching between the circulation purging and the discharge purging is performed by designing the flow path resistance of the entire nozzle 32 to be small in advance and switching the pressure contact / isolation of the rubber pad 115 to the nozzle surface 36. For this reason, in the former circulation purging, all the ink 400 pressurized by the pump 120 is returned to the sub chamber 13 via the return path 37, and bubbles in the forward path 35, the return path 37, and the vicinity of the branch point of the nozzle 32 are removed. The included ink 400 can be replaced with clean ink 400. During this time, the ink 400 is not wasted at all.
[0050]
  In the subsequent discharge purging, most of the ink 400 pressurized by the pump 120 can be discharged from the nozzle 32. By this discharge purging, the ink 400 in the nozzle 32 can be replaced with a clean ink 400. At this time, the ink 400 in the forward path 35 and the return path 37 has already been replaced with clean ink 400. For this reason, in the discharge purging, the entire ejection path of the ink 400 can be sufficiently purified even if the minimum amount of ink 400 necessary for discharging only the bubbles and dust in the nozzle 32 is sent. That is, when the discharge purging is performed, bubbles and the like do not flow into the nozzle 32 from the forward path 35 or the like. Therefore, waste of the ink 400 due to discharge purging, and hence waste of the ink 400 in the entire maintenance operation can be satisfactorily suppressed.
[0051]
  Further, in the present ink jet printer, circulation purging and discharge purging are reliably switched by the configuration of the rubber pad 115 and the like, and these are sequentially executed. In addition, the ink 400 in the sub chamber 13 returns to the main chamber 11 via the communication path 21 without passing through the return path 37. Furthermore, since the one-way valve 221 is provided at the sub chamber inlet 22b, even if the ink 400 containing bubbles or the like is stored in the sub chamber 13, the ink 400 flows into the ejection path via the return path 37. There is no. For this reason, the ejection path of the ink 400 can be purified very reliably, and the occurrence of ejection failure and the like can be suppressed extremely well. As described above, in the present ink jet printer, the ejection path of the ink 400 can be purified very reliably, and the waste of the ink 400 can be suppressed very well.
[0052]
  In the above embodiment,WThe one-way valve 221 corresponds to one-way valve means. The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention.
[0053]
  For example, in the above-described embodiment, the pressure contact valve 28 and the one-way valve 221 are provided at the sub chamber inlet 22b, and both of these have the effect of suppressing the back flow of the ink 400.SoIt is possible to better suppress the back flow of the ink 400.wear. Therefore, in the above-described embodiment, the ejection path of the ink 400 can be more reliably purified, and the occurrence of ejection failure and the like can be further suppressed. The switching means for switching the pressure contact / separation of the rubber pad 115 can also be configured by another actuator such as a solenoid.
[0054]
  The sealing means for sealing the opening of the nozzle head 31 is not limited to the rubber pad 115, and maintenance paper can also be used. FIG. 10 is a cross-sectional view illustrating a configuration of a maintenance unit 800 that uses roll paper 700 as maintenance paper. The maintenance unit 800 is provided at the position where the rubber pad 115 is provided in the above-described embodiment, that is, at the right end of the guide surface 101 so as to face the nozzle head 31 moved to the purging position. The maintenance unit 800 has substantially the same configuration as the “maintenance unit 100” described in Japanese Patent Application No. 9-194533, and the pump 120 is driven by the motor drive circuit 70c (that is, a drive system that drives the roll paper 700). Differ only in that they are driven independently.
[0055]
  As shown in FIG. 10, since the roll paper 700 is a consumable item, it is held in the cassette 780, and after use, the entire cassette 780 is replaced or only the roll paper 700 is replaced. Supply to the user is performed both in the cassette 780 and the set of the roll paper 700 for replacement, and the user can select the one that is convenient for the user.
[0056]
  Inside the cassette 780, pins 783 that protrude from the inner wall surface and support the unused roll paper 700, a fixed amount feed roller 785 (FIG. 11) that conveys the roll paper 700, and the conveyed roll paper 700 are provided. A take-up shaft 787 for taking up and a pressure contact plate 789 for pressing the roll paper 700 against the nozzle head 31 are provided. Note that the side wall of the cassette 780 on which the pins 783 are formed has a substantially U-shaped cut to form a spring portion S. For this reason, the pin 783 swings outward when the roll paper 700 is loaded, and later returns with an elastic force to support the paper tube of the roll paper 700.
[0057]
  Further, a long hole 791 extending in a direction perpendicular to the nozzle surface 36 is formed on the side wall of the cassette 780, and a pin 793 a formed on the support portion 793 of the press contact plate 789 is fitted into the long hole 791. As shown in FIG. 11, the pressure contact plate 789 includes the support portion 793, a plate portion 795 that is swingably connected to the support portion 793 via a pin 795a, and the plate portion 795 that is separated from the support portion 793. And a compression coil spring 797 to be urged. In addition, in the cassette 780, a nip roller 798 that is pressed against the fixed amount feed roller 785 and sandwiches the roll paper 700 is provided.
[0058]
  Further, as shown in FIG. 10, guide pins 780c are projected from the left and right side surfaces of the cassette 780. The pin 780c is fitted with guides 804 and 805 formed on the side frames 802 and 803 of the maintenance unit 800 together with the winding shaft 787 protruding from the side surface of the cassette 780, and guides the cassette 780 to the normal mounting position. Is. When the cassette 780 is mounted along the guides 804 and 805, the movable portions 811 and 813 of the sensor 810 disposed below the cassette 780 swing around the shafts 811a and 813a. When the cassette 780 is completely attached, the movable portion 811 on the carriage 3 side comes into contact with the roll paper 700 held by the pins 783 in the cassette 780. This sensor 810 detects the presence or absence of the roll paper 700 based on the swinging state of the movable portion 811.
[0059]
  Further, the cassette 780 is opened at a portion facing the nozzle head 31, and as described below, when the press contact plate 789 moves in the direction of the nozzle head 31, the roll paper 700 protrudes outside the cassette 780 and enters the nozzle surface 36. Press contact. That is, the pin 793a of the press contact plate 789 protruding to both sides of the cassette 780 through the long hole 791 is centered on the front end of the maintenance unit 800 (carriage 3 side: hereinafter, the front and rear are similarly defined for the cassette 780). Engage with the tip of the arm 815 that swings to the right. A lever 817 that swings in contact with the carriage 3 is provided further forward of the maintenance unit 800, and the pressure contact plate 789 projects as follows according to the swing of the lever 817.
[0060]
  The lever 817 is disposed so as to be able to swing around a shaft protruding in front of the maintenance unit 800 (parallel to a shaft 825, which will be described later), and when the carriage 3 moves to the above-described purging position, It is pushed and swings so that the upper part in FIG. 10 is tilted forward. The lever 817 is integrally formed with a bevel gear 817 a centering on the axis, and the bevel gear 817 a meshes with a bevel gear 823 a formed integrally with the pressing piece 823. The pressing piece 823 is installed between the shaft and a shaft 825 protruding in parallel with the shaft 825 so as to be swingable about a shaft perpendicular to the paper surface of FIG. Swings clockwise. The pin 793a and the arm 815 are similarly configured on the left side of the maintenance unit 800 (that is, the back side in FIG. 10), and an iron plate 829 is installed on the front end portions of the pair of arms 815. And the front-end | tip of the press piece 823 presses the iron plate 829 with the said rocking | fluctuation. Each arm 815 includes an upper arm 831 that swings about a shaft 815a, and a lower arm 833 that is swingably connected to a substantially intermediate portion of the upper arm 831 via a stepped caulking pin 833b. The front end portion of 831 is fixed to the left and right end edges of the iron plate 829 or both of them are integrally bent by a single metal plate. A tension coil spring 835 is installed between the front end of the lower arm 833 and the lower end of the iron plate 829. The front end (rear end) of the lower arm 833 is urged upward by the tension coil spring 835, and the lower end of the lower arm 833 is lower than the protruding piece 831c bent at the lower edge of the front end of the upper arm 831 in a normal state. A state in which the edge is in contact, that is, a state where a gap 815b is formed between the rear ends of the upper arm 831 and the lower arm 833 so that the pin 793a just fits is formed.
[0061]
  When the iron plate 829 is pressed by the pressing piece 823 as described above, the entire arm 815 swings counterclockwise in FIG. 10 about the shaft 815a, and the press contact plate 789 protrudes together with the roll paper 700. When the pressure contact plate 789 abuts against the nozzle head 31 and the like with the roll paper 700 interposed therebetween, the lower arm 833 is rotated clockwise in FIG. 10 against the urging force of the tension coil spring 835 around the stepped caulking pin 833b. Swing. Thereby, the impact at the time of contact with the nozzle head 31 or the like can be reduced. Further, when the pressing force from the pressing piece 823 does not act, the arm 815 is held at the lowered position by the action of the leaf spring 837.
[0062]
  Next, operations of the pressure contact plate 789 and the roll paper 700 accompanying the movement of the carriage 3 will be described with reference to FIGS. When the carriage 3 moves to the purging position, the pressure contact plate 789 protrudes upward as described above, and the plate portion 795 is pressed against the nozzle surface 36 of the nozzle head 31 with the roll paper 700 interposed therebetween as shown in FIG. . A pair of protrusions 795b are formed on the surface of the plate portion 795 along the upper and lower edges, and the roll paper 700 is stretched between the protrusions 795b. For this reason, extremely good flatness is ensured for the roll paper 700 on the surface of the plate portion 795, and the roll paper 700 adheres well to the nozzle surface 36. By this operation, dirt around the nozzle surface 36 can be wiped off. If the pump 120 is driven in this state, the opening of the nozzle 32 can be sealed in the same manner as when the rubber pad 115 is pressed and the above-described circulation purging can be performed.
[0063]
  At this time, the roll paper 700 is firmly sandwiched between the lower end of the plate portion 795 on the side where the pin 795 a is provided and the nozzle head 31. Then, when the constant feed roller 785 and the take-up shaft 787 are subsequently driven and the roll paper 700 is conveyed, tension is applied to the roll paper 700 installed between the lower end of the plate portion 795 and the constant feed roller 785. Due to this tension, the plate portion 795 swings downward (clockwise in FIG. 11) about the pin 795a against the urging force of the compression coil spring 797. For this reason, as shown in FIG. 12, the roll paper 700 is retracted, and a gap is provided between the nozzle surface 36 and the roll paper 700. If the pump 120 is driven in this state, since the nozzle surface 36 is open, the aforementioned discharge purging can be executed.
[0064]
  In this case, since the lower end of the plate portion 795 is pressed against the nozzle head 31 with the roll paper 700 interposed therebetween, the discharged ink 400 can be well received by the roll paper 700. Further, since the ink 400 can be discharged while the roll paper 700 is being conveyed, it is possible to prevent the discharged ink 400 from being accumulated and adhering to the nozzle surface 36 again. Furthermore, if the roll paper 700 is continuously conveyed even after the pump 120 is stopped, the unused roll paper 700 that is not soiled can be disposed on the surface of the plate portion 795. For this reason, the purification of the nozzle surface 36 by the next maintenance operation can be performed more satisfactorily. In addition, after the discharge purging is completed, the unused roll paper 7 that is not soiled in this way is disposed on the surface of the plate portion 795, the carriage 3 is once moved to the left to be separated from the lever 817, and then again the purging position. As shown in FIG. 11, the unused roll paper 7 is brought into pressure contact with the nozzle surface 36. By this operation, ink remaining on the nozzle surface 36 after purging can be wiped off.
[0065]
  Even when the sealing means (corresponding to the roll paper 700) and the switching means (corresponding to the press contact plate 789, the arm 815, the lever 817, and the pressing piece 823) are configured in this way, the circulation is performed in the same manner as in the above-described embodiment. The same operation and effect can be obtained by performing purging and discharge purging. Further, when the sealing means is configured using the maintenance paper such as the roll paper 700 as described above, the mechanical configuration is somewhat complicated. By making it oppose to 36, the effect that the nozzle surface 36 can be more favorably purified arises.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic configuration of an ink jet printer to which the present invention is applied.
FIG. 2 is an exploded perspective view illustrating a configuration of a head of the printer.
FIG. 3 is a top view illustrating a configuration of an ink tank of the head.
FIG. 4 is a cross-sectional end view taken along the line BB and CC of the ink tank.
FIG. 5 is a cross-sectional view illustrating the configuration and operation of a one-way valve of the head.
FIG. 6 is an explanatory diagram illustrating the purge operation of the head.
FIG. 7 is an explanatory diagram schematically showing the configuration of the head.
FIG. 8 is an explanatory diagram schematically showing a configuration of a control board of the printer.
FIG. 9 is a flowchart showing processing executed by the CPU of the control board at startup.
FIG. 10 is a cross-sectional view illustrating a configuration of a maintenance unit according to another embodiment.
FIG. 11 is an explanatory diagram showing an operation of circulating purging by the maintenance unit.
FIG. 12 is an explanatory diagram showing an operation of discharge purging by the maintenance unit.
FIG. 13 is a schematic diagram illustrating a configuration of a conventional inkjet head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Head, 5 ... Guide shaft, 8 ... Carriage motor, 10 ... Ink tank, 11 ... Main chamber, 13 ... Sub chamber, 21 ... Communication path, 24 ... Valve opening / closing lever, 27, 28 ... Pressure contact valve, 29 ... Filter 31 ... Nozzle head, 32 ... Nozzle, 35 ... Outward path, 36 ... Nozzle surface, 37 ... Return path, 38 ... Piezoelectric conversion element, 40 ... Melting tank, 50 ... Cam, 70 ... Control panel stage, 115 ... Rubber pad, 117 ... Pad, drive motor, 120 ... pump, 221 ... one-way valve, 400 ... ink.

Claims (1)

A main chamber for storing ink;
A sub chamber connected to the main chamber via a communication path;
A nozzle head having a nozzle for ejecting ink stored in the main chamber onto a recording medium;
An outward path for supplying ink from the main chamber to the nozzle head;
A return path for returning ink from the nozzle head to the sub chamber;
Purge means for purging by supplying ink stored in the main chamber to the forward path ;
Valve means for opening and closing the communication path;
Valve control means for switching whether the communication path is opened or closed by the valve means;
An inlet hole formed in the sub chamber and into which ink from the return path flows is allowed to allow ink to flow from the return path to the sub chamber and to prevent ink from flowing from the sub chamber to the return path. One-way valve means;
A sealing means capable of sealing the opening of the nozzle when the purge means performs a purge;
A switching means for switching whether or not to perform sealing by the sealing means when the purge means performs purging,
The flow path resistance of the entire nozzle is smaller than the flow path resistance of the return path,
Further, the purge means is purged in a state where the communication path is closed by the valve control means and the sealing means is sealed by the switching means,
The inkjet printer is characterized in that the communication path is closed by the valve control means and the purge means is purged in a state where the sealing is released by the switching means .

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