JP5286012B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an ink supply device that supplies ink to a printer head that performs desired printing by discharging ink.

  An ink jet printer using the printer head is configured to perform desired printing by ejecting ink from nozzles formed on the lower surface of the printer head while moving the printer head relative to the print medium. Ink jet printers consume ink as ink is ejected, so an ink tank (ink cartridge) with a capacity corresponding to the application is provided in the carriage of the printer head or the printer body. For example, in a large inkjet printer that prints commercial large format advertisements and banners, a large amount of ink is consumed in a relatively short time. For this reason, in such a commercial inkjet printer, a large-capacity ink tank is generally provided in the printer body, and the ink tank and the printer head are connected by a tube or the like, and ink is ejected in accordance with ink ejection. Ink is supplied from the tank to the printer head.

  Here, when the internal pressure of the printer head becomes higher than the atmospheric pressure, the ink is pushed out from the nozzle and dripped onto the print medium, thereby causing a problem of so-called “dropping off”. Therefore, conventionally, a configuration using an ink supply (sub tank) is known so that the internal pressure of the printer head becomes a slightly negative pressure slightly lower than the atmospheric pressure. As a configuration example of a conventional sub tank, a sub tank having a small capacity ink chamber is provided between an ink tank (main tank) provided in the printer main body and a printer head provided in the carriage, and the ink chamber of the sub tank is adjusted. There is known a “negative pressure generation method” in which a printer head is brought into a slightly negative pressure state by reducing pressure by a pressure means (see, for example, Patent Document 1).

In this sub-tank, for example, in one hollow part formed inside, a predetermined volume of ink is stored in the lower part of the hollow part, and an air chamber connected to the pressure adjusting means is formed above the stored ink. There is something that was done. In the sub tank configured as described above, the pressure adjusting means adjusts the inside of the sub tank to a negative pressure state by sucking the air in the air chamber, while adjusting the pressure to a positive pressure state by feeding air into the air chamber. Yes. If the ink is excessively supplied and stored, the ink may flow into the pressure adjusting means. In order to avoid such a situation, for example, the liquid level of conventionally stored ink is detected. However, excessive ink supply was prevented.
JP 2004-284207 A

  However, in the sub tank configured as described above, the ink is stored in one hollow portion, and the pressure adjusting space is present above the hollow portion. When the ink is continuously supplied, the entire hollow portion is filled with the excessively supplied ink, and there is a possibility that the ink flows into the pressure adjusting means relatively easily.

  The present invention has been made in view of the problems as described above, and is an ink supply capable of regulating the flow of ink into the pressure adjusting means even when the ink is excessively supplied with a simple configuration. The purpose is to provide a vessel.

  In order to achieve the above object, the ink supply device according to the present invention (for example, the sub-tank 120 in the embodiment) has a hollow portion formed therein and is connected to a printer head that discharges liquid ink and performs desired printing. An ink supply means for supplying liquid ink to the printer head, wherein the hollow portion is an ink supply means for supplying liquid ink from a tank (for example, the main tank 110 in the embodiment) in which the liquid ink is stored. For example, the first ink chamber (for example, the ink storage chamber 123 in the embodiment) that is connected to the liquid feed pump 118) in the embodiment and supplies the supplied liquid ink to the printer head after being temporarily stored, and the ink A second ink chamber (for example, the float storage chamber 124 in the embodiment) communicating with the side of the chamber, and the hollow An isolation wall is formed between the pressure adjusting means for adjusting the internal pressure (for example, the air feed pump 160 in the embodiment) and the first ink chamber, and the upper end portion of the second ink chamber is And an air chamber communicating with the air chamber.

  The ink supply unit is preferably formed in a substantially rectangular parallelepiped, and the ink supply unit is configured to be connected to a side surface of the ink supply unit (for example, the front wall 121f in the embodiment), and the pressure adjusting unit. Is preferably connected to the upper surface of the ink supply device (for example, the ceiling wall 121t in the embodiment).

  In the ink supply device according to the present invention, the air chamber connected to the pressure adjusting means is separated from the first ink chamber connected to the ink supply means by the isolation wall and communicates with the upper end of the second ink chamber. Is formed. With this configuration, for example, ink excessively supplied to the first ink chamber flows into the air chamber from the upper end of the second ink chamber, and flows into the air chamber while preventing the ink from rising all at once by the isolation wall. be able to. Therefore, it is possible to prevent excessively supplied UV ink from flowing into the air chamber at a stretch and reaching the pressure adjusting means. In other words, it is possible to extend the time required for the UV ink to reach the pressure adjusting means. it can. In the meantime, for example, by flowing air from the pressure adjusting means into the air chamber, it is possible to reliably prevent ink from flowing into the pressure adjusting means. In this way, the ink flows into the pressure adjusting means even when the ink is excessively supplied, although it is a simple configuration in which the isolation wall is provided to form the air chamber isolated from the first ink chamber. Can be regulated.

  The ink supply means is preferably connected to the side surface of the ink supply formed in a substantially rectangular parallelepiped, and the pressure adjusting means is preferably connected to the upper surface of the ink supply. When configured in this manner, for example, a first ink chamber and a second ink chamber arranged side by side at a lower portion of a hollow portion formed in the ink supply device, and an air chamber positioned above these can be formed. it can. Therefore, the ink excessively supplied to the first ink chamber is first stored in the first ink chamber and the second ink chamber, and when the ink is continuously supplied, the ink chamber gradually moves from the ink chamber to the air chamber. Can be allowed to flow into. Therefore, it is possible to prevent the excessively supplied ink from flowing into the air chamber at a stretch and reaching the pressure adjusting means.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As an example of an ink jet printer to which the present invention is applied, a type in which a printer head is reciprocated and printing is performed while a print medium is fed in a direction perpendicular to the printer head is taken, and an ultraviolet curable ink that is cured by being irradiated with ultraviolet light ( A configuration example applied to a UV curable inkjet printer (hereinafter referred to as a printer device) that discharges so-called UV ink from a printer head will be described. 1 and 2 are perspective views of the printer device P of the present embodiment, and FIG. 3 shows the configuration of the main part 1 of the printer device P. The entire printer device P is described with reference to these drawings. The configuration will be described. In the following description, directions indicated by arrows F, R, and U added in FIG. 1 will be referred to as front, right, and upward, respectively.

  The printer device P is broadly divided into an apparatus main body 1 supported by the support unit 2, a feed mechanism 3 that feeds an unprinted print medium M provided before and after the support unit 2, and a print medium M that has finished drawing. A winding mechanism 4 for winding is configured. In the apparatus main body 1, a horizontally long window-shaped medium insertion portion 15 that allows the print medium M to be inserted back and forth in the frame 10 is formed, and the print medium M is supported by the lower frame 10 </ b> L positioned below the media insertion portion 15. A platen 20 and a medium moving mechanism 30 for feeding the print medium M back and forth are provided (see FIG. 3). A carriage 40 that holds the printer head 60 and a carriage moving mechanism 50 that moves the carriage 40 to the left and right are provided on the upper frame 10U positioned above the media insertion portion 15. The apparatus body 1 is provided with a control unit 80 which will be described later, and an operation panel 88 provided with various operation switches and the like is disposed on the front surface of the apparatus body 1.

  The platen 20 is provided on the lower frame 10 </ b> L so as to extend back and forth below the media insertion portion 15, and a media support portion 21 for horizontally supporting the print medium M is provided in the left and right belt-like drawing areas by the printer head 60. Is formed. The medium moving mechanism 30 includes a cylindrical feed roller 31 whose upper peripheral surface is exposed to the platen 20, a roller driving motor 33 that rotates the feed roller 31 via a timing belt 32, and the like. A roller assembly 35 having a pinch roller 36 rotatably supported is disposed on the left and right. The roller assembly 35 is configured to be set to a clamp position where the pinch roller 36 is pressed against the feed roller 31 and an unclamp position separated from the feed roller 31. The print medium M is sandwiched between the pinch roller 36 and the feed roller 31, the roller assembly 35 is set to the clamp position, and the roller drive motor 33 is rotationally driven to feed the print medium M forward and backward by a predetermined distance. Can do. In FIG. 3, both the clamp position and the unclamp position are shown.

  The carriage 40 is supported by a guide rail 45 attached to the upper frame 10U so as to be movable left and right, and is driven by a carriage driving mechanism 50 described later. A printer head 60 that discharges UV ink is mounted on the carriage 40 with a predetermined gap from the media support portion 21. FIG. 5 is a perspective view of the periphery of the carriage. In FIG. 5, the printer head 60 is used for each of the four colors of UV inks of cyan (C), magenta (M), yellow (Y), and black (K). The case where (first printer head 60C, second printer head 60M, third printer head 60Y, fourth printer head 60K) is provided is illustrated. The carriage 40 is provided with subtanks 120 (first subtank 120C, second subtank 120M, third subtank 120Y, and fourth subtank 120K), which will be described in detail later, corresponding to the printer head 60. Note that the printer head 60 in the present embodiment exemplifies a configuration that ejects ink by a piezo method.

  The left and right side portions of the carriage 40 are provided with a left UV light source 70L and a right UV light source 70R that irradiate ultraviolet light toward the print medium M, and are configured using, for example, a UV lamp or a UV-LED. The blinking operation of the left UV light source 70L and the right UV light source 70R is controlled by the control unit 80 in accordance with the movement of the carriage 40 and the ejection of ink from the printer head 60. The carriage moving mechanism 50 is wound around a drive pulley 51 and a driven pulley 52 provided on the left and right sides of the frame 10, a carriage drive motor 53 that rotates the drive pulley 51, and the drive pulley 51 and the driven pulley 52. The endless timing belt 55 is formed (see FIG. 3). The carriage 40 is fixed to a timing belt 55 and is moved left and right above the platen 20 along the guide rail 45 in accordance with the drive of the carriage drive motor 53.

  The control unit 80 performs arithmetic processing on a ROM 81 in which a control program for each component is written, a RAM 82 for temporarily storing the program, a program read from the RAM 82, an operation signal input from the operation panel 88, and the like. The arithmetic processing unit 83 is mainly configured. The control unit 80 controls the operation of each component such as the medium moving mechanism 30, the carriage moving mechanism 50, the printer head 60, the ink supply device 100 described later, and the like.

  For example, when drawing on the print medium M based on the print program read into the control unit 80, the forward / backward movement M of the print medium by the medium moving mechanism 30 and the left / right movement of the carriage 40 by the carriage moving mechanism 50 are combined. The print medium M and the printer head 60 are moved relative to each other. Simultaneously with this relative movement, a UV light source (for example, the left UV light source 70L when the carriage is moved to the right) is turned on while discharging ink from each printer head 60 toward the printing medium M. Then, information corresponding to the printing program is drawn.

Thus, in the printer apparatus P schematically configured, the printer head 60 is used during printing.
UV ink is supplied from the ink supply device 100 to the printer head 60 in accordance with the amount of UV ink consumed. 4 is a system diagram of the ink supply apparatus 100, FIG. 6 is an external perspective view of the sub-tank 120, FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6, and FIG.

  The ink supply device 100 includes a sub-tank 120 connected to the printer head 60, a main tank 110 storing UV ink, a sub-tank decompression unit 140 for reducing the internal pressure of the sub-tank 120 to a negative pressure state, and an internal pressure of the sub-tank 120 being a positive pressure state. A sub tank pressurizing unit 150 that pressurizes the main tank 110, an ink transfer unit 115 that transfers UV ink stored in the main tank 110 to the sub tank 120, and the like. (See FIG. 4).

  As the main tank 110, a tank capable of storing a capacity corresponding to the consumption amount of UV ink per unit time in the printer device P is selected. 2 shows the cartridge-type main tanks 110 (first main tank 110C, second main tank 110M, third main tank 110Y, and fourth main tank 110K) for the above four colors, respectively, on the rear surface of the apparatus main body 1. Fig. 1 shows an example of a configuration that is detachably disposed.

  As shown in FIG. 6, the sub tank 120 is made of, for example, a resin material that covers and seals the opening surface of the container member 121 on a thin rectangular box-shaped container member 121 that opens to one side (right side of the sheet). A flexible transparent sheet member 122 is welded and sealed by the sheet member 122, whereby an ink storage chamber 123, a float storage chamber 124, and an air chamber 124a are formed. A thin plate member 122a made of, for example, a metal material and formed in a lattice shape is sandwiched between the opening surface of the container member 121 and the sheet member 122, and the opening surface is partially covered by the thin plate member 122a. . In the present embodiment, a configuration in which the ink storage chamber 123 and the float storage chamber 124 are covered by the thin plate member 122a is illustrated, but the air chamber 124a may also be covered.

In the ink storage chamber 123, for example, a predetermined volume of UV ink is stored during printing,
A groove-like float storage chamber 124 that communicates with the ink storage chamber 123 and extends vertically is formed behind the ink storage chamber 123. A disk-shaped float 134 that floats on UV ink is accommodated in the float chamber 124 so as to be movable up and down. A magnet 134 a is fixed to the center of the float 134. Above the ink storage chamber 123 and the float storage chamber 124, an air chamber 124a that communicates with the upper end of the float storage chamber 124 and is separated from the ink storage chamber 123 by the isolation wall 124b is formed. In the present embodiment, a configuration in which the end surface on the right side of the separation wall 124b is not welded to the sheet member 122 is illustrated. Further, since at least one of the container member 121 and the sheet member 122 is formed using a transparent or translucent material, the storage state of the UV ink in the ink storage chamber 123, the floating state of the float 134, and the like from the outside. It is configured to allow visual confirmation.

  A short cylindrical connector portion 125 projecting downward from the bottom wall 121 b of the container member 121 is formed on the lower surface side of the sub tank 120, and the connector portion 125 and the printer head 60 are connected using a tube 69. (See FIGS. 6 and 7). A block-shaped duct portion 126 extending upward from the bottom wall 121b to the inside of the ink storage chamber 123 is formed on the upper portion of the connector portion 125. A first lead-out path 127a that penetrates the bottom wall 121b up and down is formed so as to connect the ink storage chamber 123 and the connector part 125, and a second lead-out path 126b that penetrates the duct part 126 up and down is formed. The cross-sectional area of the first lead-out path 127a is smaller than the cross-sectional area of the second lead-out path 126b. Therefore, the ink storage chamber 123 and the printer head 60 are connected via the first lead-out path 127a and the second lead-out path 126b. When printing is not being performed, the carriage 40 is controlled to move to a reference position (home position), and a bat-shaped ink tray that receives UV ink is located below the printer head 60 positioned at the reference position. 180 is provided (see FIG. 5).

  A storage detector 130 that detects the storage state of the UV ink in the ink storage chamber 123 is provided on the rear surface side of the sub tank 120. The storage detection unit 130 detects the magnetic level of the above-described float 134 that moves up and down together with the liquid level of the UV ink in the ink storage chamber 123, and the magnet 134a fixed to the float 134, and detects the liquid level of the UV ink. The liquid level detection sensor 138 is configured. On the rear wall 121r of the container member 121, a groove-shaped sensor mounting portion 131 extending in the vertical direction is formed, and the liquid level detection sensor 138 is mounted on the sensor mounting portion 131. For example, a case member 137 to be described later is attached. The liquid level detection sensor 138 is fixed to the rear wall 121r by inserting and fastening the mounting screw 139 into the hole 137a (see FIG. 7).

  The liquid level detection sensor 138 includes a liquid level detection substrate 135 to which a limit detection sensor 136E, a Hi detection sensor 136H, and a Lo detection sensor 136L are attached in order from the top, and a case member 137 that accommodates the liquid level detection substrate 135. The Each of the detection sensors 136E, 136H, and 136L can be configured using, for example, a Faraday element or a magnetic impedance element, and a Hall element is preferably used. Various magnets can be used as the magnet 134a, and an anisotropic ferrite magnet is preferably used.

  As shown in FIG. 7, the liquid level detection sensor 138 is disposed opposite to the float 134 with the rear wall 121r interposed therebetween, and detects the magnetism of the magnet 134a by the detection sensors 136E, 136H, and 136L, thereby increasing the height of the magnet 134a. The position, that is, the liquid level of the UV ink in the ink storage chamber 123 can be detected. As can be seen from FIG. 7, since the inner wall of the float storage chamber 124 and the front and rear side surfaces of the float 134 (magnet 134a) are close to each other, the float 134 can be substantially omitted from the float storage chamber 124 according to the liquid level of UV ink. It is configured to move up and down straight.

  In a state where the liquid level detection sensor 138 is fixed to the sensor mounting portion 131, the Hi detection sensor 136H detects that the liquid level of the UV ink in the ink storage chamber 123 has reached the highest position, while the Lo detection sensor 136L. Detects that the liquid level of the UV ink has reached the lowest position. The limit detection sensor 136E is positioned above the Hi detection sensor 136H, detects that the liquid level of the UV ink has risen beyond the maximum position, and is positioned below the upper end of the float storage chamber 124. Yes. The liquid level height of the UV ink thus detected is output from the liquid level detection sensor 138 to the control unit 80.

  An ink introduction path (not shown) penetrating the front wall 121f of the container member 121 back and forth is formed on the front side of the sub tank 120 so as to communicate with the ink storage chamber 123. A tube connector 128 is connected to the ink introduction path. Is inserted. Further, a gas introduction path (not shown) penetrating the ceiling wall 121t of the container member 121 vertically is formed on the upper surface side of the sub tank 120 so as to communicate with the air chamber 124a. A tube connector 129 having a gas introduction hole 129a formed therein is inserted.

  The ink transfer unit 115 is formed by a main supply circuit 116 that connects between the main tank 110 and the sub tank 120. The main supply circuit 116 includes an ink suction line 117 a connected to the main tank 110 and the liquid feed pump 118, an ink delivery line 117 b connected to the liquid feed pump 118 and the tube connector 128, and UV ink from the main tank 110 to the sub tank. The liquid feed pump 118 supplied to 120 is configured.

  The sub tank decompression unit 140 is formed by a negative pressure circuit 141 that connects between the sub tank 120 and the suction port 161 of the air pump 160. The negative pressure circuit 141 includes an air chamber 142, a pressure sensor 144 that detects the pressure of the negative pressure circuit 141, a negative pressure control valve 145 that opens and closes the negative pressure circuit 141, as shown by being surrounded by a frame A in FIG. 4, and A line 147 (147a, 147b, 147c, 147d) or the like connecting these devices to connect between the suction port 161 of the pneumatic pump and the sub tank 120 is configured. In FIG. 4, a portion surrounded by a frame C is provided on the carriage 40, and a portion outside the frame is a device provided on the apparatus main body 1.

  The air chamber 142 is connected to the suction port 161, and is configured such that the air in the chamber is exhausted and reduced to a negative pressure state by the operation of the air feed pump 160. An air introduction line 147i for introducing air into the inside is provided. The air introduction line 147i is provided with a flow rate adjustment valve 143a for adjusting the flow rate of air and an air filter 143b for dust removal. The flow rate adjusting valve 143a adjusts the flow rate of the air flowing into the air chamber 142 in a state where the air pump 160 and the sub tank 120 are connected via the negative pressure circuit 141, thereby making the internal pressure of the air chamber 142 constant.

  The negative pressure control valve 145 is located between the air chamber 142 and the sub tank 120, and is an electromagnetic valve that switches the line 147c and the line 147d between a communication state and a cutoff state. FIG. 4 exemplifies a configuration using a three-way valve as the negative pressure control valve 145. A line 147c is connected to the common port (COM), a line 147d is connected to the normally open port (NO), and a normally closed port (NC) is shown. ) Is open to the atmosphere via line 147x and silencer 148.

  For this reason, when the negative pressure control valve 145 is off (during normal operation such as printing or standby, and at the time of ink filling), the line 147c and the line 147d are connected to bring the negative pressure circuit 141 into a communication state. The suction port 161 and the sub tank 120 are connected via a junction circuit 171 described later. On the other hand, when the negative pressure control valve 145 is on (during cleaning or the like), the connection between the line 147c and the line 147d is cut off, the negative pressure circuit 141 is cut off, and the line 147c is connected to the line 147x. The circuit on the suction port side of the feed pump 160 is opened to the atmosphere.

  The sub tank pressurizing unit 150 is formed by a positive pressure circuit 151 that connects between the sub tank 120 and the discharge port 162 of the pneumatic pump 160. The positive pressure circuit 151 includes a flow rate adjustment valve 153a that adjusts the flow rate of air, a dust filter air filter 153b, and a pressure sensor 154 that detects the pressure of the positive pressure circuit 151, as shown by being surrounded by a frame B in FIG. From a positive pressure control valve 155 that opens and closes the positive pressure circuit 151, and a line 157 (157a, 157b, 157c, 157d) connecting these devices to connect the discharge port 162 of the air pump 160 and the sub tank 120, etc. Composed. The flow rate adjustment valve 153a is a valve that adjusts the internal pressure of the ink storage chamber 123 so as not to exceed a predetermined value in a state where the air pump 160 and the sub tank 120 are connected by the positive pressure circuit 151.

  The positive pressure control valve 155 is located between the flow rate adjustment valve 153a and the sub tank 120, and is an electromagnetic valve that switches the line 157c and the line 157d between a communication state and a cutoff state. FIG. 4 illustrates a configuration using a three-way valve as the positive pressure control valve 155. A line 157c is connected to the common port (COM) of the positive pressure control valve 155, and a line 157d is connected to the normal close port (NC). The normally open port (NO) is open to the atmosphere via a line 157x and a silencer 158.

  For this reason, when the positive pressure control valve 155 is off (during normal operation such as printing or standby, and at the time of ink filling), the connection between the line 157c and the line 157d is disconnected and the positive pressure circuit 151 is cut off. In addition, the line 157c is connected to the line 157x, and the positive pressure circuit on the discharge port side of the air feed pump 160 is opened to the atmosphere. On the other hand, when the positive pressure control valve 155 is on (for cleaning or the like), the line 157c and the line 157d are connected, the positive pressure circuit 151 is set in a communication state, and the discharge port 162 and the sub tank 120 are connected to the junction circuit 171. Connected through.

  The pneumatic pump 160 is a pump that sucks air from the negative pressure circuit 141 connected to the suction port 161 and pumps the sucked air to the positive pressure circuit 151 connected to the discharge port 162. A pump that generates a predetermined positive / negative pressure is used for the port 161. The negative pressure circuit 141 and the positive pressure circuit 151 merge on the way to the sub tank 120, and a merge circuit 171 is formed. The junction circuit 171 includes a line 177 connected to the sub tank 120 and a junction circuit opening / closing valve 175 that opens and closes the junction circuit 171. The junction circuit open / close valve 175 is provided corresponding to the number of sub-tanks 120. In FIG. 4, the junction circuit 171 (line 177) is branched into four, and each of the branched junction circuits (lines 177C and 177M) is branched. , 177Y, 177K, part numbers omitted) are illustrated as being individually openable and closable.

  In the printer apparatus P configured as described above, as shown in FIG. 8, detection results obtained by the pressure sensors 144 and 154 and the liquid level detection sensor 138 are input to the control unit 80, and from the operation panel 88. The operation signal is input. The control unit 80 controls the operation of the liquid feed pump 118, the air feed pump 160, the negative pressure control valve 145, the positive pressure control valve 155, and the junction circuit opening / closing valve 175 based on these input results.

  Hereinafter, the operation control by the control unit 80 will be described. Since the UV ink supply system is the same for the four systems (C, M, Y, K), the items common to each system in the following description will be described by omitting these subscripts. .

  When the main power supply of the printer apparatus P is turned on, the control unit 80 drives the air feed pump 160 and turns on all the junction circuit open / close valves 175. After the junction circuit opening / closing valve 175 is turned on, the negative pressure control valve 145 and the positive pressure control valve 155 are both turned off, so that in the negative pressure circuit 141, the line 147c and the line 147d communicate with each other for suction. The port 161 and the ink storage chamber 123 are connected, and in the positive pressure circuit 151, the line 157c and the line 157x are connected, and the circuit on the discharge port side of the air feed pump 160 is opened to the atmosphere. In this way, the air feed pump 160 is continuously driven regardless of whether the printing program is being executed or on standby, and the internal pressures of the four ink storage chambers 123 are always set to the same negative pressure. Retained.

  As described above, when the internal pressure of the storage chamber 123 is set to a negative pressure, the sheet member 122 can be bent (inward) in the sub tank 120 to absorb (relax) the internal pressure variation. The configuration is such that excessive external force does not act on the component. Further, since the ink storage chamber 123 and the float storage chamber 124 are partially covered by the thin plate member 122a, the sheet member 122 can be prevented from being excessively bent toward the inside of the sub tank 120. Therefore, for example, the sheet member 122 and the float 134 do not come into contact with each other, and the vertical movement of the float 134 according to the liquid level height of the UV ink can be secured, so that the accurate liquid level height can be detected. Further, for example, when the UV ink in the sub tank 120 is once discharged and cleaning is performed, the internal pressure of the storage chamber 123 is set to a positive pressure, contrary to the above. In this case, the sheet member 122 is configured to absorb the fluctuation in the internal pressure by bending toward the outside of the sub tank 120.

  During normal printing, the control unit 80 controls each component so that a certain amount of UV ink is always stored in the ink storage chamber 123 of the sub tank 120. The control will be specifically described. The UV ink stored in the ink storage chamber 123 is discharged and consumed from the nozzles of the printer head 60 by the execution of a printing program or the like and gradually decreases. When the UV ink stored in the ink storage chamber 123 decreases, the liquid level of the UV ink decreases, and the float 134 is moved downward in the float storage chamber 124 according to the liquid level. Then, when the magnetism of the magnet 134a is detected by the lowest position Lo detection sensor 136L, the control unit 80 activates the liquid feed pump 118 in a state where the ink storage chamber 123 is depressurized to a negative pressure state. The UV ink sent from the main tank 110 by the driving of the liquid feed pump 118 is supplied to the ink storage chamber 123 from the tube connector 128 through the line 117b. When the supply of the UV ink to the ink storage chamber 123 is continued, the liquid level of the UV ink gradually increases, and when the magnetism of the magnet 134a is detected by the highest position Hi detection sensor 136H, the control is performed. The unit 80 stops driving the liquid feed pump 118 and completes the replenishment of UV ink.

  When replenishing the UV ink, the control unit 80 stops driving the liquid feed pump 118 by detecting the magnetism of the magnet 134a by the Hi detection sensor 136H. For example, the drive of the liquid feed pump 118 is stopped. Therefore, a slight time lag may occur before the supply of UV ink is actually stopped. As described above, since the internal pressure of the ink storage chamber 123 is set to a negative pressure, the UV ink supplied excessively during this time lag is sucked into the gas introduction hole 129a and flows into the line 177. There is a fear. In order to avoid such a situation, the sub tank 120 according to the present invention is provided with a limit detection sensor 136E and an air chamber 124a in addition to the liquid level detection sensor 138.

  First, the operation of the limit detection sensor 136E will be described. When the magnetism of the magnet 134a is detected by the limit detection sensor 136E when UV ink is replenished, the control unit 80 stops driving the liquid feed pump 118. In the state, the negative pressure control valve 145 and the positive pressure control valve 155 are turned on. That is, the communication between the line 147c and the line 147d is cut off, and the line 157c and the line 157d are connected to each other to connect the discharge port 162 of the air feed pump and the ink storage chamber 123 of the first sub tank 60c for a short time. The inside of the ink storage chamber 123 is set to a positive pressure state (for example, for 1 second). By doing so, the UV ink is not sucked into the gas introduction hole 129a and does not flow into the line 177, and further, a so-called “dropping” problem also occurs due to the positive pressure state only for a short time. do not do.

  By providing the limit detection sensor 136E and further providing an air chamber 124a (separation wall 124b) according to the present invention, if UV ink is excessively supplied to the ink storage chamber 123, the UV ink is floated. The upper end portion of the chamber 124 and the sheet member 122 can be allowed to flow into the air chamber 124a by passing through a slight gap between the sheet member 122 and the upper end portion of the separation wall 124b. Therefore, for example, compared to a configuration in which the isolation wall 124b is not formed and the air chamber 124a is not provided, excessively supplied UV ink can be prevented from rising to the gas introduction hole 129a all at once. It is possible to increase the time until the gas reaches the lower end of the gas introduction hole 129a. In the meantime, for example, by setting the inside of the ink storage chamber 123 to a positive pressure state as described above, it is possible to more reliably prevent the UV ink from being sucked into the gas introduction hole 129a.

  In the above-described embodiment, the thin plate member 122a made of a metal material and formed in a lattice shape has been described as an example. However, the present invention is not limited to this configuration. For example, when the inside of the ink storage chamber 123 is set to a negative pressure, the material and shape of the sheet member 122 are not limited as long as the sheet member 122 can be prevented from being bent excessively inside the sub tank 120.

  In the above-described embodiment, the configuration in which the liquid level detection sensor 138 is detachable from the sub tank 120 has been described. For example, the limit detection sensor 136E, the Hi detection sensor 136H, the Lo detection sensor 136L, and the liquid level detection substrate 135 may be incorporated in the sub tank 120.

  In the above-described embodiment, the liquid level detection sensor 138 has been described by exemplifying the configuration in which the liquid level detection substrate 135 is accommodated in the case member 137. However, the present invention is not limited to this configuration. For example, the liquid level detection board 135 is not accommodated in the case member 137, and the liquid level is constituted by the limit detection sensor 136E, the Hi detection sensor 136H, the Lo detection sensor 136L, and the liquid level detection board 135 to which these are attached. The detection sensor may be mounted on the sub tank 120.

  In the above-described embodiment, as shown in FIG. 7, the magnet 134a is fixed to the center of the float 134, and the vertical position of the magnet 134a and the liquid level position of the UV ink are exemplified. It is not limited. For example, when the float 134 having the magnet 134a fixed to the upper end portion is floated in the UV ink, the positional relationship between the liquid surface position of the UV ink and the fixing position of the magnet 134 is known. Considering the fixing position, a configuration in which the limit detection sensor 136E, the Hi detection sensor 136H, and the Lo detection sensor 136L are arranged is also possible.

  Further, in the above-described embodiment, as an example of the ink jet printer to which the present invention is applied, the configuration example applied to the UV curable ink jet printer of the uniaxial printing medium movement and the uniaxial printer head movement has been described. However, the present invention can also be applied to other forms of jet printers, for example, a biaxial printer head moving type or a biaxial printing medium moving type ink jet printer. The present invention can be applied to an ink jet printer using other types of ink.

It is the external appearance perspective view which showed the printer apparatus to which this invention was applied from diagonally forward. It is the external appearance perspective view which showed the said printer apparatus from diagonally backward. It is the front view which showed the principal part structure of the apparatus main body of the said printer apparatus. It is a systematic diagram of an ink supply apparatus. It is the perspective view which showed the carriage periphery of the said printer apparatus. It is the external appearance perspective view which showed the sub tank provided in the carriage. It is sectional drawing which showed the VII-VII part in FIG. It is a schematic block diagram of an ink supply apparatus.

Explanation of symbols

60 printer head (60C: first printer head, 60M: second printer head, 60Y: third printer head, 60K: fourth printer head)
110 main tank (110C: first main tank, 110M: second main tank, 110Y: third main tank, 110K: fourth main tank) (tank)
118 Liquid feed pump (ink supply means)
120 sub tanks (120C: first sub tank, 120M: second sub tank, 120Y: third sub tank, 120K: fourth sub tank) (ink supply unit)
121f Front wall (side)
121t Ceiling wall (top)
123 Ink storage chamber (first ink chamber)
124 Float storage chamber (second ink chamber)
124a Air chamber 124b Separation wall 160 Pneumatic pump (pressure adjusting means)

Claims (2)

A hollow part is formed inside, an ink supply unit that is connected to a printer head that discharges liquid ink and performs desired printing and supplies the liquid ink to the printer head, and a liquid from a tank that stores the liquid ink An ink jet printer comprising: ink supply means for supplying ink; and pressure adjusting means for adjusting the pressure in the hollow portion to adjust the pressure in the hollow portion to a positive pressure and a negative pressure,
The hollow portion is
A first ink chamber connected to the ink supply means and temporarily supplying the supplied liquid ink to be supplied to the printer head;
A second ink chamber communicating with the side of the first ink chamber and storing liquid ink supplied from the first ink chamber;
An air chamber connected to the pressure adjusting means, forming an isolation wall between the first ink chamber and communicating with an upper end portion of the second ink chamber, and an upper and lower air chamber;
The inkjet printer includes a float that floats on the liquid ink in the second ink chamber, and a liquid level detection sensor that detects a liquid level of the liquid ink in the first ink chamber by detecting the position of the float. Prepared ,
The ink supply means supplies the liquid ink to the first ink chamber so that the liquid level detected by the liquid detection sensor is between a predetermined minimum position and a predetermined maximum position;
The ink-jet printer , wherein the pressure adjusting unit adjusts the pressure in the hollow portion to a positive pressure when the liquid level detected by the liquid detection sensor rises beyond the highest position .   The ink supply is formed in a substantially rectangular parallelepiped,
  The ink supply means is configured to be connected to a side surface of the ink supply;
  The inkjet printer according to claim 1, wherein the pressure adjusting unit is configured to be connected to an upper surface of the ink supply unit.

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