JP2012240328A - Inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus having a pressure applying means for applying a pressure into a recording head via an ink tank, and capable of restraining the ink from leaking from a communication path communicating between the ink tank and the pressure applying means.SOLUTION: In a negative pressure control system to aggressively control the negative pressure to be guided into a sub tank 80 through an atmosphere communication pipe 83 by an air fan 85, the ink overflowing from the sub tank 80 into the atmosphere communication pipe 83 is detected by an overflow detection part 100.

Description

  The present invention relates to an ink jet recording apparatus that records an image by ejecting ink from a recording head onto a recording medium.

  In an ink jet recording apparatus, it is important to maintain a predetermined negative pressure in the recording head in order to stabilize the ink ejection operation of the recording head. For this reason, generally, a pressure applying means for applying a negative pressure to the recording head is provided. As the pressure applying means, a configuration that generates a negative pressure using the capillary action of an ink absorber accommodated in an ink tank connected to the recording head, and a configuration that applies a negative pressure to ink using a water head difference It has been known. Furthermore, a negative pressure control method (Patent Document 1) has been proposed in which the negative pressure in the ink tank connected to the recording head is positively controlled by controlling the rotation of the air fan.

  By such a negative pressure control system, the negative pressure in the recording head can be maintained constant via the ink tank in response to a sudden change in the amount of ink discharged from the recording head per unit time. In particular, in the case of an industrial recording apparatus that records an image on a large format recording medium at a high speed, the amount of ink ejected from the recording head per unit time varies greatly, so the negative pressure in the recording head is reduced. It tends to fluctuate. By stably maintaining the negative pressure of the ink in the recording head in such an industrial recording apparatus by the negative pressure control method, the ink ejection operation is stabilized, and a high-quality image is recorded at high speed. be able to.

JP 2006-326855 A

  However, in the negative pressure control method described in Patent Document 1, there is no consideration on how to cope with an abnormality in which an excessive negative pressure is generated in the ink tank. If the negative pressure introduced into the ink tank by the air fan becomes excessively large, the ink flows from the ink tank into the communication path between the air fan and the ink tank, and the ink flows from the communication path. There is a risk of leakage (overflow). When such an overflow occurs, the leaked ink may cause contamination in the recording apparatus, breakage of electrical components, or the like.

  It is an object of the present invention to have a pressure applying unit that applies pressure to the recording head via an ink tank, and to suppress leakage of ink from a communication path that connects the ink tank and the pressure applying unit. And providing an ink jet recording apparatus.

  The inkjet recording apparatus of the present invention is an inkjet recording apparatus that records an image on a recording medium using a recording head capable of ejecting ink supplied from an ink tank from an ejection port. A communication pipe, a pressure sensor for detecting the pressure in the ink tank, a pressure applying means connected to the atmosphere communication pipe for applying a predetermined negative pressure in the ink tank, and a pressure sensor. And pressure detecting means for controlling driving of the pressure applying means, and detecting means for detecting that ink has flowed into the atmospheric communication pipe from the ink tank.

  “Recording” as used herein is not limited to the case where significant information such as characters and figures is formed. In other words, regardless of whether it is significant involuntary, or whether it is manifested so that humans can perceive it visually, when forming images, patterns, patterns, etc. on recording media widely, This includes cases where processing is performed. The “recording medium” (also referred to as a sheet) is not only paper used in general recording apparatuses but also widely accepts ink such as cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. Including what is possible. Further, the term “ink” should be broadly interpreted in the same way as the definition of “recording”. That is, by being applied on the recording medium, formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium) It shall contain the liquid provided to.

  According to the present invention, it is possible to suppress the leakage of ink from the atmosphere communication pipe by detecting the ink flowing into the atmosphere communication pipe from the ink tank, and to record when overflow occurs. It is possible to avoid contamination in the apparatus and breakage of electrical parts.

1 is a schematic front view of an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 2 is a block configuration diagram of a control system of the recording apparatus in FIG. 1. (A) is a schematic block diagram of the ink supply system in the recording apparatus of FIG. 1, (b) is a schematic block diagram of the air fan in (a). (A) is a schematic perspective view of an overflow detection part, (b) is a wiring diagram of the overflow detection part. It is a flowchart for demonstrating an overflow countermeasure process. It is a schematic block diagram of the principal part of the ink supply system in the 2nd Embodiment of this invention. It is a schematic perspective view of the overflow detection part in FIG. It is a wiring diagram of the overflow detection part of FIG. It is a schematic perspective view of the overflow detection part in the 3rd Embodiment of this invention. FIG. 10 is a wiring diagram of the overflow detection unit in FIG. 9. It is a schematic block diagram of the overflow detection part in the 4th Embodiment of this invention. It is a schematic block diagram of the ink supply system in the 6th Embodiment of this invention. 16 is a flowchart for explaining ink discharge processing according to a sixth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic front view of the ink jet recording apparatus according to the present embodiment.

  A host device (host PC) 12 for sending image information to the recording device 10 is connected to the recording device 10. In the recording apparatus 10, four recording heads 22K, 22C, 22M, and 22Y are arranged side by side in the conveyance direction (arrow A direction) of the recording medium (here, roll paper) P. The four recording heads 22K, 22C, 22M, and 22Y can eject black, cyan, magenta, and yellow ink, respectively. These four recording heads 22K, 22C, 22M, and 22Y (hereinafter collectively referred to as “recording head 22”) are so-called line heads, and the transport direction (direction of arrow A) of the roll paper P as a recording medium. It extends in the crossing direction. In the case of this example, the recording head extends in a direction orthogonal to the transport direction (direction orthogonal to the paper surface of FIG. 1). The recording head 22 is fixed and does not move during the image recording operation. A plurality of nozzles are arranged along the extending direction of the recording head 22, and each nozzle is an electrothermal conversion element (heater) as an ejection energy generation element that generates energy for ejecting ink. And piezo elements. When the electrothermal conversion element is used, the ink is foamed by the heat generation, and the ink can be ejected from the ejection port using the foaming energy.

  A recovery unit 40 is incorporated in the recording apparatus 10 so that the recording head 22 can stably eject ink. By the recovery operation of the recovery unit 40, the recording head 22 is maintained in a desired ink discharge state. The capping mechanism 50 provided in the recovery unit 40 is capable of capping a blade for wiping the discharge port forming surface (surface on which the discharge port is formed) of the recording heads 22K, 22C, 22M, and 22Y and a discharge port during the recovery operation. A cap is included.

  Roll paper P as a recording medium is fed out from the supply unit 24 and conveyed in the direction of arrow A by a conveyance mechanism 26 incorporated in the recording apparatus 10. The transport mechanism 26 includes a transport belt 26a that transports the roll paper P, a transport motor 26b that rotates the transport belt 26a, a roller 26c that applies tension to the transport belt 26a, and the like.

  When recording an image on the roll paper P, from the time when the recording start position of the roll paper P being conveyed reaches the lower position of the black ink discharge recording head 22K, based on the recording data (image information), Black ink is ejected from the nozzles of the recording head 22K. Similarly, when the recording start position of the roll paper P reaches the lower position of the recording head 22C, the recording head 22M, and the good recording head 22Y, from the nozzles, cyan, magenta, and yellow are output from these nozzles. Ink is ejected. As a result, a color image is recorded on the roll paper P. The recording apparatus 10 includes a main tank 28 (28K, 28C, 28M, 28Y) for storing ink supplied to the recording head 22 (22K, 22C, 22M, 22Y). Further, the recording apparatus 10 is provided with a pump, which will be described later, for supplying ink to the recording head 22 and performing recovery operations.

  FIG. 2 is a block diagram of the control system of the recording apparatus 10.

  Recording data and commands transmitted from the host PC 12 are received by the CPU 150 via the interface controller 102. The CPU 150 is an arithmetic processing unit that performs overall control of the recording apparatus 10 such as reception of recording data, recording operation, handling of the roll paper P, and the like. After analyzing the received command, the CPU 150 renders the image data of each color component of the recording data by developing a bitmap on the image memory 106.

  In the recording operation, first, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor driving unit 116 to move the recording head 22 away from the capping mechanism 50 to the recording position. Thereafter, the roll paper P is recorded by driving a roll motor (not shown) that feeds the roll paper P and a transport motor 26b that transports the roll paper P at a low speed via the output port 114 and the motor drive unit 116. Transport to position. By detecting the leading edge of the conveyed roll paper P by a not-illustrated leading edge sensor (not shown), the timing (recording) for starting the ejection of ink from the recording head to the rolled paper P conveyed at a constant speed. Timing). Thereafter, the CPU 150 sequentially reads the recording data from the image memory 106 in synchronization with the conveyance of the roll paper P, and transfers the recording data to the recording head 22 via the recording head control circuit 112.

  The operation of the CPU 150 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores a table and the like in addition to a processing program corresponding to the control flow. The work RAM 108 is used as a working memory. During the cleaning or recovery operation of the recording head 22, the CPU 150 drives the pump motor 124 via the output port 114 and the motor driving unit 116 to pressurize the ink in the recording head and discharge the ink in the recording head. To control the suction and so on.

  3A is a schematic configuration diagram of an ink supply system for the recording head 22, and FIG. 3B is a schematic plan view of a main part of the air fan in FIG. 3A.

  The recording apparatus 10 includes a main tank 28 that can be attached to and detached from the main body of the recording apparatus 10, and a sub tank (ink tank) 80 disposed in an ink supply path 62 between the main tank 28 and the recording head 22. Etc. are provided. The recording head 22 is disposed below the sub tank 80. A total of four sub tanks 80 are provided so as to individually correspond to the recording heads 22K, 22C, 22M, 22Y and the main tanks 28K, 28C, 28M, 28Y.

  The ink flow path 64 connects between the bottom of the sub tank 80 and the upper part of the liquid chamber 22 </ b> A of the recording head 22. An atmospheric valve 67 for opening and closing the ink flow path 64 is attached to the ink flow path 64. The entire shape of the sub tank 80 is a rectangular parallelepiped, and a space 82 is formed in the upper part thereof. This space is usually filled with air and not filled with ink. The ink is located in the lower part of the sub tank 80. The upper part of the space 82 is surrounded by the upper wall 82a.

  An air communication pipe 83 attached to the upper wall 82a of the sub tank 80 allows the inside of the space 82 to communicate with the atmosphere through an air fan 85 that is a pressure applying unit that applies pressure to the recording head 22. An atmosphere release valve 84 that can open and close the atmosphere communication pipe 83 is attached to the atmosphere communication pipe 83. The space 82 communicates with the atmosphere when the atmosphere release valve 84 is opened, and is blocked from the atmosphere when the atmosphere release valve 84 is closed. When the recording apparatus 10 is not in operation, the atmosphere release valve 84 is closed to prevent the ink in the sub tank 80 from evaporating. In order to detect the amount of ink stored in the sub tank 80, a well-known liquid level sensor 86 (liquid remaining amount detecting means) for detecting the liquid level of the ink is attached. In the liquid level sensor 86 of this example, the conductive state between the electrodes 86a, 86b, 86c changes according to the ink remaining amount in the sub tank 80, and the ink liquid level is changed to the first, second, third. Are detected in three stages. The first range is less than the lower limit level LA, the second range is greater than or equal to the lower limit level LA and less than the upper limit level LB, and the third range is greater than or equal to the upper limit level LB.

  By opening the air release valve 84 and rotating the air fan 85 in one direction (in the direction of arrow C1 in FIG. 3B), part of the air in the space 82 is discharged to the outside through the air communication pipe 83. Is done. As a result, the pressure in the space 82 becomes lower than the atmospheric pressure, and this low pressure acts on the sub tank 80, the ink flow path 64, the liquid chamber 22A, and the nozzle N, via the ink tank. A negative pressure (pressure lower than atmospheric pressure) is applied to the recording head. On the other hand, by opening the atmosphere release valve 84 and reversing the air fan 85 in the other direction (the direction of arrow C2 in FIG. 3B), outside air is introduced into the space 82 through the atmosphere communication pipe 83. Is done. As a result, the pressure in the space 82 becomes higher than the atmospheric pressure, and this high pressure acts on the ink in the subtank 80, the ink flow path 64, the liquid chamber 22A, and the nozzle N to correct the ink. Apply pressure (pressure higher than atmospheric pressure). Thus, the pressure in the space 82 of the sub tank 80 can be controlled in the pressure reducing direction and the pressure increasing direction in accordance with the rotation direction of the air fan 85. Furthermore, the degree of decompression and the degree of pressurization in the space 82 can be positively controlled according to the rotational speed of the air fan 85. Thus, the rotation direction and rotation speed of the air fan 85 can be controlled.

  The main tank 28 is provided with a detection sensor (not shown) for detecting the presence or absence of ink inside the main tank 28. The main tank 28 is connected to an air flow path when mounted on the main body of the recording apparatus 10, and an air release valve (tank valve) for introducing atmospheric pressure into the main tank 28 is provided in the air flow path. 74 is attached. When the liquid level sensor 86 detects that the liquid level of the ink in the sub tank 80 has become less than the lower limit level LA, the tank valve 74 is opened, the supply pump 72 starts to operate, and the main tank 28 The ink inside is supplied into the sub tank 80. On the other hand, when the liquid level sensor 86 detects that the ink level in the sub tank 80 has reached the upper limit level LB or more, the supply pump 72 is stopped, the tank valve 74 is sealed, and the sub tank 80 is closed. Ink supply to the printer stops. A tube pump is used as the supply pump 72, and when it is not operating, the flow path between the main tank 28 and the sub tank 80 is blocked. Thereby, the liquid level of the ink in the sub tank 80 is maintained within a predetermined range that is equal to or higher than the lower limit level LA and lower than the upper limit level LB. As described above, the supply pump 72 is operated based on the detection signal of the liquid level sensor 86, whereby the ink in the main tank (in the main ink tank) is supplied into the sub tank (in the ink tank).

  In order for the recording head 22 to eject ink droplets satisfactorily, it is necessary to apply a predetermined negative pressure in the recording head 22 to form an ink meniscus at the ejection port at the tip of the nozzle N. In order to apply such a negative pressure, as described above, the air valve 85 and the air release valve 84 are opened, and the air fan 85 is rotated in the direction of the arrow C1 so as to reduce the pressure in the sub tank 80. The pressure in the space 82 of the sub tank 80 is detected by the pressure sensor 103. The pressure sensor 103 of this example is provided in the portion of the atmospheric communication pipe 83 between the overflow detection unit 100 and the sub tank 80. The air fan 85 in the atmosphere communication pipe is rotationally controlled based on the pressure detected by the pressure sensor 103 in order to control the pressure to apply a predetermined negative pressure in the sub tank (in the ink tank).

  During execution of the recording operation, when the liquid level sensor 86 detects that the ink level in the sub-tank 80 has become lower than the lower limit level LA, the tank valve 74 is opened and the ink supply pump 72 is activated. Ink is supplied into the sub tank 80. The supply of ink into the sub-tank 80 is continued until the liquid level sensor 86 detects that the ink level has reached the upper limit level LB. When such ink is supplied into the sub tank 80, air corresponding to the volume of ink flowing into the sub tank 80 is immediately discharged to the outside by the air fan 85, and fluctuations in pressure within the sub tank 80 are kept within a certain allowable range. It is necessary to keep in. The pressure in the sub tank 80 is detected by the pressure sensor 103. The air fan 85 is required to be capable of discharging the air in the sub tank 80 so as to satisfy such a condition. If an air fan satisfying such conditions cannot be installed due to problems such as the installation space of the air fan 85, ink may be supplied into the sub tank 80 after temporarily stopping the recording operation. After the ink supply into the sub tank 80 is completed, the ink supply pump 72 is stopped and the tank valve 74 is sealed.

  The air fan 85 that is a pressure applying unit may be any unit that can apply a predetermined pressure to the space 82 of the sub tank 80 through the atmosphere communication pipe 83, and the configuration thereof is not limited. For example, a normal liquid transfer pump such as a gear pump (gear pump) or a screw pump can be used. Preferably, the air fan 85 is a pump generally referred to as a turbo pump. The reason for this is that if a turbo type air fan is used, the flow of air to and from the atmosphere can be controlled while a certain range of negative pressure is applied to the sub-tank 80, and the negative pressure in the sub-tank 80 varies greatly. It is because it is hard to exert. As described above, after the pressure in the sub tank 80 is reduced by the air fan 85, ink flows into and out of the sub tank 80 due to consumption of ink during the recording operation and supply of ink from the main tank 28 to the sub tank 80. .

  As the atmospheric valve 67 and the atmospheric release valve 84, an electromagnetic valve that blocks a flow path by a valve seat 132 integrated with a solenoid plunger can be adopted. Of course, various types of bubbles can be used.

  The overflow detection unit 100 detects ink that has flowed (overflowed) from the subtank 80 into the atmosphere communication pipe 83 and notifies the overflow control unit 110 of the occurrence of overflow.

  FIG. 4A is a schematic perspective view for explaining the configuration of the overflow detection unit 100. The overflow detection unit 100 is provided in the atmosphere communication pipe 83 between the sub tank 80 and the atmosphere release valve 84. When the ink overflowed from the sub tank 80 into the atmosphere communication pipe 83 reaches the inside of the overflow detection unit 100, the overflowed ink is interposed between the pair of electrodes 31 and 32, and the electrode is connected via the ink. Make it conductive. Thus, the overflow of ink is detected by the electrodes 31 and 32 being in a conductive state. The overflow detection unit 100 is connected to the overflow control unit 110 as shown in FIG. That is, when one of the electrodes 31 and 32 is connected to the power source and the other is connected to the overflow control unit 110, the voltage is applied to the overflow control unit 110 when the electrodes 31 and 32 become conductive due to the overflowed ink. Applied. As a result, the overflow control unit 110 is notified of the occurrence of overflow, which is a state in which ink flows from the sub tank 80 into the atmosphere communication pipe 83.

  The overflow detection unit 100 is provided in a portion (a portion extending upward from the sub tank) extending in the vertical direction in the atmosphere communication pipe 83. Thereby, when maintenance of negative pressure and supply of ink are stopped in the overflow control described later, the overflowed ink can be returned into the sub tank 80 by its own weight without requiring special control.

  FIG. 5 is a flowchart for explaining an overflow countermeasure process when an overflow is detected. This overflow countermeasure process is executed by the overflow control unit 110 under the control of the CPU 150 (see FIG. 2) when the overflow detection unit 100 detects an overflow of ink. The overflow control unit 110 checks whether or not the overflow detection unit 100 has detected an ink overflow periodically or at a specific time such as when the recording apparatus is started.

  After receiving the overflow detection notification from the overflow detection unit 100, the overflow control unit 110 first stops the air fan 85 (step S1), closes the air release valve 84 (step S2), and stops the supply pump 72. (Step S3). In these processing steps S102, S103, and S104, the power is cut off so that the air fan 85, the atmosphere release valve 84, and the supply pump 72 are stopped by hardware. By these processes, negative pressure is not introduced into the sub tank 80, and ink supply into the sub tank 80 is also stopped. As a result, overflow of the overflowed ink to the outside, and damage to the electrical components associated therewith can be prevented.

  Next, it is determined whether or not the liquid level sensor 86 has detected the liquid level of the ink at the upper limit level LB or higher. (Step S4). When the liquid level of the ink of the upper limit level LB or higher is detected, it is considered that the liquid level sensor 86 is operating correctly, and the liquid level sensor 86 is not considered to cause the overflow. In this case, it is determined whether or not an operation command for the supply pump 72 (a drive command for the pump motor 124) has been issued (step S5). When the operation command for the supply pump motor has been issued, supply is performed so as to supply ink into the sub tank 80 even though the liquid level sensor 86 operates correctly and detects ink above the upper limit level LB. The pump 72 is operating. In this case, it is determined that the cause of the overflow is a software runaway (step S6), and the determination result is notified to the CPU 150 (step S7). Step S12 is processing in a sixth embodiment to be described later.

  If the operation command for the supply pump 72 has not been issued in the determination in step S5, the liquid level sensor 86 operates correctly to detect ink above the upper limit level LB, and the operation command for the supply pump 72 has not been issued. Nevertheless, the supply pump 72 is operating. In this case, it is determined that the cause of the overflow is a failure of the supply pump 72 (step S8), and the determination result is notified to the CPU 150 (step S7).

  In step S4, if the liquid level sensor 86 has not detected ink of the upper limit level LB or higher, the liquid level sensor 86 is not detected even though the overflow detection unit 100 has detected an ink overflow. Ink above the level is not detected. Therefore, in this case, it is considered that the liquid level sensor 86 is not operating correctly. In this case, it is determined whether or not an operation command for the supply pump 72 has been issued (step S9). If the operation command for the supply pump 72 has been issued, the liquid level sensor 86 is not operating correctly, and it cannot detect the ink above the upper limit level LB, so that the supply pump 72 cannot be stopped. Conceivable. In this case, it is determined that the cause of the ink overflow is the failure of the liquid level sensor 86 (step S10), and the determination result is notified to the CPU 150 (step S7).

  If the operation command for the supply pump 72 is not issued in the determination in step S9, the liquid level sensor 86 does not operate correctly and ink above the upper limit level cannot be detected, and the operation command for the supply pump 72 is issued. The supply pump 72 is considered to be operating despite the absence. In this case, it is determined that the cause of the ink overflow is the failure of the liquid level sensor 86 and the supply pump 72 and the runaway of the software (S112), and the determination result is notified to the CPU 150 (step S7).

  In this manner, the cause of the ink overflow is determined based on the detection signal of the liquid level sensor 86 and the operating state of the supply pump 72. Receiving the notification of the determination result, the CPU 150 notifies the user of the determination result. For example, the determination result can be displayed on the display unit of the recording apparatus or notified to an external host device. Further, depending on the cause of the overflow, it is possible to notify or execute a process necessary to avoid the influence.

  As described above, in this embodiment, the recording apparatus includes the overflow detection unit for detecting the overflow of the ink from the sub tank. When the overflow detection unit detects an overflow of ink, the atmosphere communication pipe 83 communicating the sub tank 82 and the fan 85 is closed by the atmosphere release valve 84 and the ink supply operation to the sub tank is stopped. As a result, overflow of the overflowed ink to the outside, and damage to the electrical components associated therewith can be prevented. Further, by determining the cause of the overflow, the portion where the abnormality has occurred can be smoothly repaired, and the recording apparatus can be restored early.

(Second Embodiment)
In the embodiment described above, one overflow detection unit 100 and one overflow control unit 110 are provided for one sub tank 80. In the present embodiment, as shown in FIG. 6, one overflow detection unit 200 and one sub tank 80K, 80C, 80M, and 80Y corresponding to each of the recording heads 22K, 22C, 22M, and 22Y are combined. An overflow control unit 210 is provided. That is, a common overflow detection unit 200 is provided for the atmospheric communication pipes 83K, 83C, 83M, and 83Y corresponding to the sub tanks 80K, 80C, 80M, and 80Y, respectively. The atmosphere communication pipes 83K, 83C, 83M, and 83Y are collected in one collecting pipe 87, and the collecting pipe 87 is provided with an atmosphere release valve 84 and an air fan 85 that are controlled by one overflow control unit 210. . In FIG. 6, an ink supply system from the sub tank 80 to the recording head 22 and an ink supply system from the main tank 28 to the sub tank 80 are not shown.

  FIG. 7 is a schematic perspective view of the overflow detection unit 200, and FIG. 8 is a wiring diagram between the overflow detection unit 200 and the overflow control unit 210.

  When any of black, cyan, magenta, or yellow ink overflows into the corresponding atmospheric communication tube 83K, 83C, 83M, 83Y, the electrodes 31, 32 are brought into conduction by the overflowed ink. Therefore, the common overflow detection unit 200 can detect that any of black, cyan, magenta, or yellow ink has overflowed. When the overflow detection unit 200 detects an ink overflow, the overflow control unit 110 closes the negative pressure supply system to the sub tanks 80K, 80C, 80M, and 80Y and stops the ink supply operation to these sub tanks. As a result, overflow of the overflowed ink to the outside, and damage to the electrical components associated therewith can be prevented. Further, the overflow control unit 110 and the CPU 150 can notify the occurrence of an overflow when the overflow detection unit 200 detects an overflow of ink, or prompt a necessary process to deal with the occurrence of the overflow.

(Third embodiment)
FIG. 9 is a schematic perspective view for explaining another configuration example of the common overflow detection unit 200 described above, and FIG. 10 is a wiring diagram between the overflow detection unit 200 and the overflow control unit 210.

  In the overflow detection unit 200 of this example, the electrode 31 is provided in common for the atmospheric communication pipes 83K, 83C, 83M, and 83Y, and the electrode 32 is an individual electrode 32K for the atmospheric communication pipes 83K, 83C, 83M, and 83Y. 32C, 32M, 32Y are provided. Therefore, in the present embodiment, as in the first embodiment, the overflow of black, cyan, magenta, and yellow ink can be detected individually. That is, when the black ink overflows, the electrodes 31 and 32K are in a conductive state, and when the cyan ink overflows, the electrodes 31 and 32C are in a conductive state. Similarly, when the magenta ink overflows, the electrodes 31 and 32M become conductive, and when the yellow ink overflows, the electrodes 31 and 32Y become conductive.

  Accordingly, as in the first embodiment described above, it is possible to individually detect the overflow of black, cyan, magenta, and yellow inks and deal with the overflow.

(Fourth embodiment)
In the embodiment described above, the overflow detection unit is configured to use electrodes. However, the configuration of the overflow detection unit is not limited to this, and may be configured using an optical sensor as in the present embodiment.

  FIG. 11 is a schematic configuration diagram of the overflow detection unit 301 of this example, which includes a light emitting diode as the light emitting element 301A and a phototransistor as the light receiving element 301B. This overflow detector 301 is provided so that when ink overflows from the sub tank 80 into the atmosphere communication pipe 83, the ink is interposed in the optical path between the light emitting element 301A and the light receiving element 301B. When the ink overflows from the sub tank 80 into the atmosphere communication pipe 83, the ink is interposed in the optical path between the light emitting element 301A and the light receiving element 301B, so that the optical path is blocked and the power supply voltage is controlled to overflow. Applied to the unit 110. As a result, the overflow of the ink is detected and notified to the overflow control unit 110.

(Fifth embodiment)
The ink overflow can also be detected based on the torque change of the air fan 85.

  When the ink overflows from the sub tank 80 into the atmosphere communication pipe 83, the load torque applied to the air fan 85 increases. Therefore, by detecting the load torque of the air fan 85, it is possible to detect ink overflow. The load torque can be detected from, for example, a detection circuit (not shown) in the drive circuit of the air fan 85, and a detection value of the drive current of the air fan 85 by the detection circuit. Further, a torque detector (not shown) may be directly attached to the air fan 85. Further, in the air fan 85, a portion where the overflowed ink may flow is coated with an insulating coating member or the like.

(Sixth embodiment)
FIG. 12 is a schematic configuration diagram of an ink supply system according to the sixth embodiment of the present invention. The same reference numerals are given to the same parts as those in FIG. .

  In the present embodiment, an ink discharge pipe 88 is branched from a portion of the atmosphere communication pipe 83 between the atmosphere release valve 84 and the air fan 85, and an overflow detection unit 100 is provided at the branch portion. . The ink discharge pipe 88 is connected to the waste ink tank 140 that stores the waste ink via the pump inlet valve 89 and the recovery pump 130, and can discharge the ink that has overflowed to the overflow detection unit 100 to the waste ink tank 140. It has become. The overflow detection unit 100 includes a pair of electrodes 101A and 101B. When the pump inlet valve 89 is closed, overflowed ink enters the overflow detection unit 100, and when the ink level rises to the position of the electrodes 101A and 101B, the electrodes 101A and 101B are in ink. Are electrically connected. Ink overflow can be detected by electrically connecting the electrodes 101A and 101B. A fan inlet valve 105 is provided between the overflow detection unit 100 and the air fan 85.

  The recovery pump 130 is connected to the capping mechanism 50 via the suction pipe 90. By applying the negative pressure generated by the recovery pump 130 through the suction pipe 90 to the inside of the capping mechanism, the ink in the recording head 22 is sucked and discharged into the cap through the nozzle N, or the ink discharged into the cap. Can be discharged into the waste ink tank. A suction valve 91 is attached to the suction pipe 90. The recovery pump 130 of this example is capable of normal rotation and reverse rotation. That is, when the ink in the cap is sucked into the waste ink tank 140 through the suction tube 90, the recovery pump 130 rotates (forward) in one direction. On the other hand, when the ink overflowed into the atmosphere communication pipe 83 is discharged into the waste ink tank 140 through the ink discharge pipe 88, the recovery pump 130 rotates (reverses) in the other direction. A filter 92 is provided in the portion of the ink discharge pipe 88 between the sub tank 80 and the overflow detection unit 100. The sub tank 80 is provided with an atmosphere opening pipe 93 and an opening valve 94.

  The overflow control unit 110 in the present embodiment basically executes an overflow countermeasure process similar to that in FIG. 5 in the first embodiment described above. However, in this embodiment, as in step S12 in FIG. 5, after detecting the cause of the overflow, a discharge process for discharging the overflowed ink is performed.

  FIG. 13 is a flowchart for explaining the discharge process.

  First, the atmosphere release valve 84 and the release valve 94 are opened, the fan inlet valve 105, the atmosphere valve 67, and the suction valve 91 are closed (step S21), and then the pump inlet valve 89 is opened (step S22). Thereafter, the recovery pump 130 is driven in reverse to discharge the ink that has overflowed into the atmosphere communication pipe 83 into the waste ink tank 140 (step S23). By such discharge processing, outside air is introduced into the sub tank 80 through the release valve 94, and the ink that has formed a meniscus in the filter 92 is also forcibly discharged. As a result, the filter 92 is cleaned and restored to a normal state free from clogging by ink. The ink that has formed a meniscus in the filter 92 obstructs the passage of the ink in the filter 92, so that it is difficult to move the ink through the filter 92 using the water head difference without using the recovery pump 130. .

  The time for which the recovery pump 130 is driven to reversely rotate may be set to the time required to discharge the ink that has overflowed into the atmosphere communication pipe 83. For example, the time when the overflow detection unit 100 no longer detects the overflowed ink is used as a reference. It may be set.

(Other embodiments)
The air fan 85 may be individually provided for the atmospheric communication pipe 83 for each sub tank 80 or may be provided in common for the atmospheric communication pipe 83. In this case, the atmospheric communication pipe 83 for each sub tank 80 is provided with a valve, and the negative pressure for each sub tank 80 can be individually controlled according to the opening degree of those valves.

  An ink circulation path including a circulation pump may be formed between the sub tank 80 and the recording head 22. In this case, the ink can be circulated through the circulation path between the sub tank 80 and the recording head 22 by operating the circulation pump as necessary.

  The above-described embodiment is an application example as a full-line type recording apparatus using a long recording head extending in the width direction of the recording medium. However, the present invention can also be applied to a serial scan type recording apparatus that involves main scanning of the recording head and reverse scanning of the recording medium.

22 (22K, 22C, 22M, 22Y) Recording head 80 Sub tank (ink tank)
83 Atmospheric communication pipe 84 Atmospheric release valve 85 Air fan 100 Overflow detection unit 103 Pressure sensor 110 Overflow control unit

Claims (9)

In an inkjet recording apparatus that records an image on a recording medium using a recording head capable of ejecting ink supplied from an ink tank from an ejection port,
An atmosphere communication pipe for communicating the inside of the ink tank with the atmosphere;
A pressure sensor for detecting the pressure in the ink tank;
Pressure application means connected to the atmosphere communication pipe and applying a predetermined negative pressure in the ink tank;
Pressure control means for controlling the driving of the pressure applying means based on the pressure detected by the pressure sensor;
Detection means for detecting that ink has flowed into the atmosphere communication pipe from the ink tank;
An ink jet recording apparatus comprising:   The inkjet recording apparatus according to claim 1, wherein the pressure control unit switches between pressurization and negative pressure by controlling driving of the pressure applying unit.   3. The ink jet recording apparatus according to claim 1, wherein the pressure control unit stops driving the pressure applying unit when the detection unit detects ink flowing into the atmosphere communication pipe. 4.   4. The ink jet recording apparatus according to claim 1, wherein the detection unit is provided in a portion of the atmosphere communication pipe that extends upward from the ink tank.   5. The ink jet recording apparatus according to claim 1, wherein the detection unit includes a pair of electrodes that are electrically connected to each other by ink flowing from the ink tank into the atmosphere communication pipe. A liquid level sensor for detecting the level of ink in the ink tank;
A supply pump for supplying ink in the main ink tank into the ink tank based on a detection signal of the liquid level sensor so as to maintain the liquid level of the ink in the ink tank within a predetermined range;
When the detection means detects ink flowing into the atmosphere communication pipe, it includes a failure of the liquid level sensor and a failure of the supply pump based on a detection signal of the liquid level sensor and an operation state of the supply pump. Determining means for determining the cause of the inflow of ink;
Notification means for notifying the determination result of the determination means;
The inkjet recording apparatus according to claim 1, comprising:   The inkjet recording apparatus according to claim 6, wherein the supply pump is stopped when the detection unit detects ink flowing into the atmosphere communication pipe. A filter provided in a portion of the atmosphere communication pipe between the ink tank and the pressure control means;
A pump for discharging the ink flowing into the atmosphere communication pipe out of the atmosphere communication pipe;
A waste ink tank containing ink discharged by the pump;
An ink jet recording apparatus according to claim 1, comprising: A cap capable of capping the ejection port of the recording head;
The ink jet recording apparatus according to claim 8, wherein the pump is capable of discharging ink in the cap into the waste ink tank.

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