JP5090219B2 - Inkjet recording apparatus and inkjet recording head - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging a liquid onto a recording medium.

  2. Related Art Inkjet recording apparatuses that perform recording by discharging ink from a recording head onto a recording medium are known. 2. Description of the Related Art Known recording heads used in ink jet recording apparatuses eject ink by various methods. Among them, a recording head that uses heat as energy used for ejecting ink generates bubbles in the ink by causing the electrothermal transducer (heater) to generate heat, and uses the pressure to eject the ink. It is. In such an ink jet recording apparatus, high-definition recording is generally performed using a small recording head in which a plurality of nozzles from which ink is ejected are formed at high density. In addition, by arranging a plurality of small recording heads and supplying different color inks to the respective recording heads, color recording can be performed on a recording medium with a relatively inexpensive and small configuration. For this reason, ink jet recording apparatuses are used in various recording apparatuses such as printers, facsimiles, and copying machines regardless of whether they are for business use or home use.

  In such an ink jet recording apparatus, in order to stabilize the ink ejection operation from the recording head, the ink in the recording head is maintained at a predetermined negative pressure (the pressure acting on the ink in the recording head is set to a predetermined negative pressure). Is important). For this reason, a negative pressure generating means is generally provided in an ink supply system for supplying ink to the recording head, and ink to which negative pressure is applied by the negative pressure generating means is supplied to the recording head.

  As a negative pressure generating means, Patent Document 1 discloses a configuration in which a negative pressure is generated using the capillary action of a sponge-like ink absorber housed in an ink tank. As another negative pressure generating means, Patent Document 2 discloses a configuration including a flexible ink bag and a bow spring. As another negative pressure generating means, Patent Document 3 discloses a configuration in which an ink tank is disposed below the recording head and a negative pressure is applied to the ink by utilizing a water head difference between the recording head and the ink tank. ing.

  In an ink supply system having negative pressure generating means as in Patent Document 1 to Patent Document 3, the negative pressure in the recording head increases as ink is ejected from the recording head. Using this increasing negative pressure, ink is supplied from the ink tank to the recording head. For this reason, when the amount of ink ejected from the recording head per unit time is large, the ink supply from the ink tank to the recording head cannot catch up, and the negative pressure in the recording head may become larger than a predetermined negative pressure. . Conversely, when the amount of ink ejected from the recording head per unit time is small, the negative pressure in the recording head may become smaller than a predetermined negative pressure due to the inertia of the ink.

  With respect to such a problem, in Patent Document 4, a sub tank (hereinafter also referred to as a storage unit) is provided between a recording head and an ink tank, and ink is supplied to the sub tank by a pump. Then, while supplying ink from the storage unit to the recording head, the negative pressure in the recording head is controlled by a fan provided in the storage unit. In this way, a configuration has been proposed in which ink supply and negative pressure control are performed separately.

Japanese Patent Laid-Open No. 2002-1988 Japanese Patent Application Laid-Open No. 06-198904 JP 2003-11380 A JP 2006-326855 A

  However, bubbles may be generated in the recording head. This is due to the deposition of dissolved gas in the ink. The dissolved gas refers to air dissolved in the ink, and generally dissolves more as the temperature is lower. Such dissolved gas increases in temperature as the ink moves to the nozzles of the recording head during the recording operation, and precipitates as the temperature increases.

  In the configuration in which the sub tank is provided between the recording head and the ink tank as in Patent Document 4, it is not considered that bubbles generated (deposited) in the vicinity of the recording head reach the sub tank, and thus remain in the recording head. There is a fear. In that case, bubbles may enter the nozzles of the recording head and ink cannot be ejected in a good state, which may reduce the recording quality.

  Accordingly, an object of the present invention is to provide an ink jet recording apparatus and an ink jet recording head in which the recording quality is not deteriorated by bubbles mixed in the recording head.

Therefore the ink-jet recording apparatus of the present invention includes an ink can eject ejection unit, provided above the discharge portion, the air for releasing the reservoir, the air in the upper space of the reservoir for storing the ink A flow path, a valve between the space and the air flow path, a negative pressure generating means for reducing the pressure in the air flow path, and a pressure in the air flow path in a state where the valve is closed And a pressure sensor for opening the valve in response to the pressure becoming lower than the pressure .

The ink jet recording head of the present invention is a discharge unit capable of discharging ink, a storage unit provided above the discharge unit, for storing the ink, and for discharging air in an upper space of the storage unit. An air flow path, a valve between the space and the air flow path, a negative pressure generating means for reducing the pressure in the air flow path, and a pressure in the air flow path with the valve closed are predetermined. And a pressure sensor for opening the valve in response to the pressure being less than or equal to the pressure .

  According to the present invention, in the ink jet recording apparatus and the ink jet recording head, the discharge part and the storage part are integrally formed, the storage part is provided above the discharge part, and bubbles generated in the discharge part pass through the storage part by buoyancy. Then, it is configured to reach the space above the reservoir. As a result, it was possible to realize an ink jet recording apparatus and an ink jet recording method in which the recording quality is not deteriorated by bubbles mixed in the recording head.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view schematically showing an ink jet recording apparatus (hereinafter also simply referred to as a recording apparatus) to which the present embodiment can be applied. The recording apparatus 10 is connected to the host PC 12, and ink is applied to the recording medium P from four recording heads (hereinafter also referred to as head units) 22K, 22C, 22M, and 22Y based on recording information transmitted from the host PC 12. Recording is performed by discharging. The four head units 22K, 22C, 22M, and 22Y are arranged along the conveyance direction (arrow A direction) of the recording medium (hereinafter also referred to as roll paper) P. The head units are arranged in the order of black ink head unit 22K, cyan ink head unit 22C, magenta ink head unit 22M, and yellow ink head unit 22Y in the transport direction. The head units 22K, 22C, 22M, and 22Y are so-called line heads, and are provided in a state where the head units 22K, 22C, 22M, and 22Y are arranged in parallel over the entire recording width in the recording medium conveyance direction. When the recording apparatus performs recording, the recording is performed by ejecting ink from the nozzles by driving a heater provided in the head unit without moving each head unit.

  The head unit changes the ejection state due to foreign matters such as dust and ink droplets adhering to the surfaces having nozzles (hereinafter also referred to as ink ejection port surfaces) 22Ks, 22Cs, 22Ms, and 22Ys during recording, which affects recording. May give. Therefore, the recovery unit 40 is incorporated in the recording apparatus 10 so that ink can be stably ejected from the head units 22K, 22C, 22M, and 22Y. By periodically cleaning the ink discharge port surface by the recovery unit 40, the ink discharge state from the nozzles of the head units 22K, 22C, 22M, and 22Y can be recovered to the initial good ink discharge state. The recovery unit 40 includes a cap 50 that removes ink from the ink discharge port surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four head units 22K, 22C, 22M, and 22Y during the cleaning operation. The cap 50 is provided independently for each head unit 22K, 22C, 22M, 22Y, and includes a blade, an ink removing member, a blade holding member, a cap, and the like.

  The recording medium P is supplied from the roll paper supply unit 24 and is transported in the direction of arrow A by the transport mechanism 26 incorporated in the recording apparatus 10. The transport mechanism 26 includes a transport belt 26a that loads and 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, when the roll paper P being conveyed reaches below the black head unit 22K, black ink is ejected from the head unit 22K based on the recording information sent from the host PC 12. Similarly, ink of each color is ejected in the order of the head unit 22C, the head unit 22M, and the head unit 22Y, and color recording on the roll paper P is completed.

  Further, the recording apparatus 10 is provided with main tanks 28K, 28C, 28M, and 28Y for storing ink to be supplied to each head unit, and a pump (see FIG. 3 and the like) for performing a cleaning operation described later. .

FIG. 2 is a block diagram showing a control system of the recording apparatus 10 of FIG.
Recording information and commands transmitted from the host PC (host device) 12 are received by the CPU 100 via the interface controller 102. The CPU 100 is an arithmetic processing unit that performs overall control such as reception of recording information of the recording apparatus 10, recording operation, handling of the roll paper P, and the like. After analyzing the received command, the CPU 100 renders the image data of each color component of the recording data by developing a bitmap on the image memory 106. In the operation process performed before recording, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor driving unit 116, and the head units 22K, 22C, 22M, 22Y are separated from the cap 50 to the recording position. Move to. Further, the CPU 100 controls the roll motor P that feeds the roll paper P, the transport motor 120 that transports the roll paper P, and the like via the output port 114 and the motor drive unit 116 to transport the roll paper P to the recording position. .

  When performing recording, the leading end detection sensor 109 detects the leading end position of the roll paper P in order to determine the timing (recording timing) at which ink is ejected onto the rolled paper P conveyed at a constant speed. Thereafter, in synchronization with the conveyance of the roll paper P, the CPU 100 sequentially reads the record information from the image memory 106 and transfers the read record information to each head unit 22K, 22C, 22M, 22Y via the head unit control circuit 112. To do.

  The operation of the CPU 100 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores processing programs and tables corresponding to the control flow. The CPU 100 uses a work RAM 108 as a working memory. Further, the CPU 100 drives the cleaning pump motor 124 via the output port 114 and the motor drive unit 116 to control the pressurization and suction of ink during the cleaning and recovery operations of the head units 22K, 22C, 22M, and 22Y. Do. The CPU 100 also performs drive control of the fan motor 125.

  FIG. 3 is a diagram schematically showing a path through which ink passes from the ink tank 28K for black ink to the head unit 22K in the recording apparatus of the present embodiment. Since the head units of the respective colors have the same structure, only the black ink head unit 22K will be described here as an example.

  The recording apparatus 10 incorporates an ink supply device 60 that supplies ink to the head unit 22K, and the head unit 22K includes a storage portion 22Kr and an ejection portion 22KSi that can eject ink. The ink supply device 60 includes an ink tank 28K that can be attached to and detached from the main body of the recording apparatus 10, and an ink supply pump 72 that is disposed in the middle of an ink supply path 62 that connects the ink tank 28K and the head unit 22K. Yes. The supply pump 72 is responsible for supplying ink to the reservoir 22Kr via the ink filter 90.

  A liquid level detection sensor 86K that detects the level of the liquid level 22Krs of the stored ink is attached to the storage unit 22Kr. Further, below the reservoir 22Kr, a nozzle 22Kn of the head unit 22K and an ejection unit 22KSi in which an ink supply port to the nozzle 22Kn is formed are connected.

  A fan 68, which is a pressure control mechanism, is connected to a space 66K filled with air (hereinafter referred to as an air chamber) 66K via an air filter 95K at the upper part of the storage unit 22Kr, and between the air filter 95K and the fan 68. Is provided with an air release valve 84 and a pressure sensor 81. The pressure sensor 81 can detect the pressure in the space of the air chamber 66. In the present embodiment, one flow path from the air chamber 66 to the fan 68 is illustrated, but a plurality of time paths or a structure that branches in the middle may be used. The pressure sensor may not be provided depending on the operational stability of the fan 68.

  A detection sensor (not shown) for detecting the presence or absence of ink in the ink tank is attached to the ink tank 28K. The ink tank 28K is provided with an air release valve 74K for setting the internal pressure of the ink tank 28K to atmospheric pressure.

  When it is determined from the measurement result of the liquid level detection sensor 86K in the storage unit 22Kr that the ink liquid level 22Krs is below a certain level, the air release valve 74 of the ink tank 28K is opened, and the supply pump 72 is operated to remove the ink from the ink tank 28K. Aspirate the ink. Then, the sucked ink is supplied into the storage portion 22Kr. On the other hand, when the liquid level detection sensor 86K detects the ink level 22Krs above a certain level, the supply pump 72 stops, the air release valve 74 of the ink tank 28K is sealed, and the ink supply is stopped.

  Incidentally, a tube pump is used as the supply pump 72, and the ink supply path 62 is shut off when the supply pump 72 is not in operation (the flow path between the ink tank 28K and the reservoir 22Kr is shut off).

  When cleaning the nozzle 22Kn in the head unit 22K, the cleaning pump 92 is driven in a direction to reduce the pressure in the cap 50, and the ink in the reservoir 22Kr is drawn into the cap 50 from the nozzle 22Kn and discharged. By discharging the ink, foreign matters such as dust accumulated around the nozzle 22Kn during the recording operation can be removed.

  FIG. 4 is a flowchart showing a procedure for cleaning the discharge port surface 22Ks of the head unit 22K. FIG. 5 is a schematic diagram showing a procedure for wiping ink from the ejection surface 22Ks with the wiper 52, (a) showing before the start of wiping, (b) showing immediately after wiping is completed, and (c) showing completion of wiping. It is a figure which shows the waiting state after. The term “cleaning” as used herein refers to an operation performed in order to continuously maintain the ink ejection of the head unit 22K in a good state. When the conditions such as the elapsed time and the ejection status are satisfied, or the recording quality is abnormal. This is an operation that is performed automatically or arbitrarily when viewed. Hereinafter, the cleaning operation will be described in order with reference to FIG.

  When the cleaning command is received in step S401, the atmosphere release valve 84 is released in step S402. Thereafter, in step S403, the cleaning pump 92 is driven in a direction to depressurize the inside of the cap 50, and the ink in the reservoir 22Kr is drawn into the cap 50 from the nozzle 22Kn and discharged. By discharging the ink, it is possible to remove foreign matters such as fine bubbles accumulated around the nozzle 22Kn during the recording operation and the like, and dust adhering to the ejection port surface 22Ks of the head unit 22K. Then, after a predetermined time has elapsed, the driving of the cleaning pump 92 is stopped at step 404 and the atmosphere release valve 84 is closed at step 405.

  In this state, ink may still adhere to the ejection port surface 22Ks including the opening of each nozzle 22Kn of the head unit 22K. Therefore, in order to remove such dirt, the discharge port surface 22Ks is wiped with a wiper 52 provided together with the cap 50, as will be described later. At that time, first, in step S406, the head unit 22K is moved above the recovery cap 50 as shown in FIG. Thereafter, in step S407, the cap 50 moves in the direction of arrow B, and as shown in FIG. 5B, dirt such as ink adhering to the discharge port surface 22Ks is wiped off by the wiper 52. This operation is called a wiping operation. After the wiping operation is completed, as shown in FIG. 5C, the head unit 22K is capped again and enters a standby state in step S408. Since the ejection port surface 22Ks is capped (closed) by the cap contact portion 54 in the head unit 22K in this standby state, there is almost no air convection in the cap 50, and the ink in the nozzle 22Kn. Can be prevented from thickening. The head unit 22K enters a standby state, and the cleaning operation ends.

  The ink (waste ink) discharged from the nozzle 22Kn is received by the cap 50 and sucked by the suction pump 92 (see FIG. 3). The sucked waste ink is pumped to a waste ink tank 71 (see FIG. 3). The waste ink tank 71 is provided with a minute air opening 75 and plays a role of releasing the pressure in the waste ink tank 71 that changes with the inflow of waste ink (and bubbles) to the atmosphere.

  FIG. 6 is an enlarged view of the head unit 22K and its surroundings. At the time of recording, it is necessary to apply an appropriate negative pressure to the head unit 22K in order to form a meniscus on the nozzle 22Kn. Therefore, the air chamber 66 in the head unit 22K is depressurized by opening the atmosphere release valve 84 and operating the fan 68 so as to create an air flow in the C direction during recording. As a result, the pressure in the nozzle 22Kn is similarly reduced through the reservoir 22Kr.

  In the present embodiment, the reservoir 22Kr communicating with the atmosphere is disposed above the discharge unit 22Ks. Therefore, when the atmosphere release valve 84 is opened, the opening at the tip of the nozzle 22Kn has a head pressure H from the liquid level 22Krs. A positive pressure acts on the nozzle 22Kn opening. For this reason, the amount of pressure reduction into the air chamber 66 by the fan 68 is set to a water head pressure H or higher. Thereby, a negative pressure is applied to the nozzle 22Kn of the head unit 22K. As a result, an ink meniscus is formed at the opening of the nozzle 22Kn.

  When the fan 68 is operated under a constant driving condition (the number of rotations), the liquid level 22Krs is lowered due to consumption of ink used during recording, and the water head difference H is also reduced. Therefore, the negative pressure acting on the nozzle 22Kn opening is reduced. The pressure increases relatively, and ink is supplied according to the lower limit detection of the liquid level position by the liquid level detection sensor 86. Conversely, until the upper limit position is detected and the ink supply is stopped, the nozzle 22Kn opening is reversed. The negative pressure acting on the is reduced. The operating conditions of the fan 68 and the detection position of the liquid level detection sensor 86 may be set so that the fluctuation of the negative pressure acting on the nozzle 22Kn opening due to this series of cycles is in a range where there is no problem.

  However, there is no problem even if the driving conditions of the fan 68 are changed as needed.

  By the way, bubbles 69 may be mixed in the reservoir 22Kr due to the deposition of dissolved gas in the ink or the ink supply operation during the recording operation and standby. The dissolved gas in the ink refers to air dissolved in the ink, and generally dissolves more as the temperature is lower. As an example of depositing such gas in the ink, the temperature of the ink rises due to the heat of the heater provided in the discharge portion 22KSi as the ink moves toward the discharge portion 22KSi during the recording operation. The case of going. Further, as an example in which bubbles are included in the ink supplied into the storage unit 22Kr, gas permeation through the supply path 62 (see FIG. 3) can be mentioned. The supply path 62 is normally filled with ink. However, when the supply path 62 is formed of a tube or the like, air in the atmosphere permeates through the tube and mixes with time. The air mixed in this way becomes bubbles and is mixed into the reservoir 22Kr with the ink supply operation. These bubbles accumulate so as to accumulate, and eventually cause a phenomenon that causes a problem in recording quality, such as blocking the ink supply path. Therefore, conventionally, ink that does not contribute to recording is discharged from the discharge port at a predetermined interval, and at the same time, the bubbles 69 are discharged to remove the bubbles, or the accumulated bubbles are pushed to a predetermined position (for example, an ink tank). The method was taken.

  In the head unit 22K of the present embodiment, the storage unit and the discharge unit are not separated as in Patent Document 4. That is, the head unit 22K is formed by integrating the storage unit and the discharge unit. With such an integrated configuration, the bubbles 69 generated in the vicinity of the discharge port easily reach the ink liquid level 22Krs via the storage portion 22Kr by buoyancy and disappear in the air chamber 66 (hereinafter referred to as gas-liquid separation). . The air bubbles 69 that have reached the air chamber 66 in this manner are released to the outside by the operation of the fan 68 that is driven to adjust the negative pressure in the head unit when the air release valve 84 is opened during recording. . That is, while the recording operation is being performed, the ink in the storage unit 22Kr is reduced by the consumption of ink by recording. However, in the configuration of the head unit 22K of the present embodiment, air having the same volume as the reduced ink is supplied to the suction ports 61 and 61. It is guided into the air chamber 66 via the air flow path 64. When the liquid level detection sensor 86 detects that the liquid level 22Krs is below a certain level, the ink supply pump 72 detects that the liquid level detection sensor 86 detects the upper limit level of the ink liquid level 22Krs. Supply ink to Also in this case, ink is supplied into the reservoir 22Kr until the upper limit level of the reservoir 22Krs is detected. Also at this time, the air corresponding to the volume of the ink flowing into the reservoir 22Kr is released to the atmosphere through the air flow path 64. Therefore, the bubbles 69 do not accumulate in the air chamber 66 and accumulate.

  However, the nozzle 22Kn is configured with an extremely fine flow path, and the bubbles 69 may not come out to the storage part 22Kr, and may remain in the discharge part 22KSi. In such a case, the bubble 69 is discharged from the nozzle 22Kn with the discharge of ink by the cleaning operation as described above. However, as noted above, most of the bubbles 69 are removed within normal operation. Therefore, only a small amount of bubbles 69 that do not come out to the reservoir 22Kr are removed here. Since such a small amount of bubbles 69 exist in the vicinity of the nozzle 22Kn, the bubbles 69 can be removed with a small amount of ink discharged by the cleaning operation.

  FIG. 7 is a flowchart showing the operation from the reception of the recording signal to the end of recording. Normally, when the recording apparatus is not used, the atmosphere release valve 84 is closed for the purpose of preventing ink leakage from the nozzle Kn. When recording is started, first, with the atmosphere release valve 84 closed, the fan 68 is operated to decompress the air flow path 64, and then the atmosphere release valve 84 is opened. Hereinafter, processing for recording will be described in order.

  When the recording apparatus 10 receives the recording signal in step S701, the process proceeds to step S702 and the fan 68 is activated. Next, in step S703, the pressure in the air flow path 64 is confirmed by the pressure sensor 81 in order to confirm whether the pressure reduction by the fan 68 is normally performed. If the predetermined pressure is not obtained, the process proceeds to step S704 to correct the rotational speed of the fan 68. If a predetermined pressure is obtained in step S703, the process proceeds to step S705 and the atmosphere release valve 84 is released. When the air release valve 84 is released, the air chamber 66 is depressurized so that a negative pressure acts on the nozzle 22Kn, and a meniscus is formed in an optimum state at the opening (discharge port) of the nozzle Kn.

  Next, in step S706, the head unit 22K is moved to the wiping position, and in step S707, the ejection port surface 22Ks of the head unit 22K is wiped. Thereafter, in order to perform recording in step 708, the head unit 22K is lowered and moved to the recording position. In step 709, recording is performed on the recording medium P. After the recording operation is completed, the head unit 22K is raised in step S710, moved to the standby position, and capped by the cap 50 again. Thereafter, the air release valve 84 is closed in step S711, the operation of the fan 68 is stopped in step S712, and the standby mode is entered again to end this flowchart.

FIG. 8 is a view showing a VIII-VIII cross section of FIG. 6.
The nozzle 22Kn in the discharge part 22KSi is formed by joining two chips of the heater board 22Kh and the supply port forming member 22Kt. The supply port forming member 22Kt is in contact with the liquid chamber 25K that forms the storage portion 22Kr, and the ink flow path of the supply port forming member 22Kt and the storage portion 22Kr communicate with each other. Further, the heater board 22Kh and the head substrate 24K are connected by an energizing wire 26K, and exchange signals between the head unit 22K and the external substrate. Further, the discharge unit 22KSi, the head substrate 24K, the liquid chamber 25K, and the like are fixed to the base plate 23K by means not shown.

  In the ink jet recording apparatus of the present embodiment, in the flow path from the contact surface between the supply port forming member 22Kt and the liquid chamber 25K to the ink liquid surface 22Krs, the bubble 69 is formed to be able to move upward by its own buoyancy. Yes. The bubbles 69 mixed in the reservoir 22Kr move upward and reach the ink liquid level 22Krs and disappear (hereinafter referred to as gas-liquid separation). Further, the ink amount in the reservoir 22Kr is maintained within a certain range by the ink supply operation described above, and the negative pressure in the head unit is adjusted by the fan 68. It does not accumulate in the air chamber 66 above 22 Kr. Although the bubbles 69 may adhere to the wall surface or the like, these bubbles 69 are fine and do not cause any adverse effects such as blocking the flow path. If it becomes larger, it will be separated from the wall surface and separated from gas.

  As described above, in the ink jet recording apparatus according to the present embodiment, the bubble 69 is removed automatically during a normal operation cycle such as a recording operation, an ink supply operation, a standby time, and the like. There is no need to implement.

  In addition, although the storage part 22Kr in the above-mentioned description has shown the structure which does not obstruct | occlude until the bubble 69 reaches the liquid level 22Krs from the nozzle 22Kn, it is not limited to this, and also has a structure as described below. Good.

  FIGS. 9 and 10 are diagrams showing head units 22Kx and 22Ky, respectively, which are modifications of the present embodiment. In the head unit 22Kx of FIG. 9, the storage unit 22Kr is provided with a partition provided with a flow path between the ejection unit 22KSi and the ink liquid level 22Krs. Since this flow path has an interval D larger than the diameter of the generated bubbles 69, it does not prevent the bubbles from rising due to buoyancy. Therefore, the bubbles 69 can pass through the flow path, and the bubbles 69 that have passed through the flow path reach the ink liquid level 22Krs and undergo gas-liquid separation.

  Similarly, the head unit 22 </ b> Ky of FIG. 10 includes a partition provided with a flow path between the ejection unit 22 </ b> KSi and the ink liquid level 22 </ b> Krs in the storage unit 22 </ b> Kr. The partition is provided with a retention portion 22Krt in which some of the bubbles remain. However, the staying portion 22Krt is configured so that the staying bubbles 70 are partially separated before the bubbles 69 are accumulated so as to block the ink flow path, and the partition has a larger interval than the diameter of the separated bubbles 69. D aperture part 22Krd is provided. As a result, the separated bubbles 69 rise to the ink level 22 Krs and are separated into gas and liquid.

  In the above modification, the head unit and the partition are integrally configured, but the present invention is not limited to this, and the head unit and the partition may be configured separately.

  In this way, the ejection unit and the storage unit of the head unit are integrally configured so that bubbles generated in the ejection unit and the storage unit can easily reach the ink level in the storage unit. As a result, gas-liquid separation is possible, and the structure in which bubbles are discharged simultaneously with the negative pressure control by the fan does not accumulate in the head unit. Therefore, the frequency of cleaning for removing bubbles is reduced, and at the same time, the amount of ink discharged that does not contribute to recording can be suppressed. In addition, the recording speed could be increased by reducing the cleaning frequency.

  Therefore, by using the ink jet recording apparatus of the present embodiment, the ink supply apparatus and the ink jet recording apparatus that can simplify the negative pressure control of the ink supplied to the ink ejection unit and can reduce the cost by simplifying the apparatus configuration associated therewith. Was able to be realized.

It is the front view which showed typically the inkjet recording device which can apply this embodiment. FIG. 2 is a block diagram illustrating a control system of the recording apparatus in FIG. 1. FIG. 5 is a diagram schematically illustrating a path through which ink passes from a black ink ink tank to a head unit in the recording apparatus of the present embodiment. It is the flowchart which showed the procedure at the time of cleaning the discharge port surface of a head unit. It is a schematic diagram which shows the procedure of wiping off ink with a wiper from a discharge surface, (a) shows before wiping start, (b) shows immediately after completion | finish of wiping, (c) is a figure which shows the standby state after completion | finish of wiping. is there. It is the figure which expanded and showed the head unit and its circumference | surroundings. It is a flowchart showing operation | movement from receiving a recording signal until recording is complete | finished. It is the figure which showed the VIII-VIII cross section of FIG. It is the figure which showed the head unit which is a modification of this embodiment. It is the figure which showed the head unit which is a modification of this embodiment.

Explanation of symbols

22K head unit 22Kn nozzle 22Kr reservoir 28K ink tank 50 cap 64 air flow path 66 air chamber 68 fan 69 bubble 84 air release valve 90 ink filter 95K air filter

Claims (2)

A discharge portion capable of ejecting ink,
A storage unit that is provided above the discharge unit and stores the ink ;
An air flow path for releasing the air in the upper space of the reservoir,
A valve between the space and the air flow path;
Negative pressure generating means for reducing the pressure in the air flow path;
An ink jet recording apparatus , comprising: a pressure sensor for opening the valve in response to a pressure in the air flow path in a state where the valve is closed being equal to or lower than a predetermined pressure . An ejection section capable of ejecting ink ;
A storage unit that is provided above the discharge unit and stores the ink ;
An air flow path for releasing the air in the upper space of the reservoir,
A valve between the space and the air flow path;
Negative pressure generating means for reducing the pressure in the air flow path;
An ink jet recording head , comprising: a pressure sensor for opening the valve in response to a pressure in the air flow path in a state where the valve is closed being equal to or lower than a predetermined pressure .

Images