Patent Publication Number: US-10766265-B2

Title: Ink jet printing apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an ink jet printing apparatus. 
     Description of the Related Art 
     There is an ink jet printing apparatus that performs a printing operation while circulating ink by supplying ink from a tank to a print head and recovering ink from the print head to the tank. 
     Japanese Patent Laid-Open No. 2011-240628 has disclosed an ink jet printing apparatus provided with a supply path for supplying ink from a storage tank to a print head and a recovery path for recovering ink from the print head to the storage tank. 
     SUMMARY OF THE INVENTION 
     Downsizing of an ink jet printing apparatus is demanded. In order to downsize an ink jet printing apparatus, it is necessary to improve compactness of an ink supply unit by appropriately configuring a flow path relating to ink, which connects a tank and a print head, and appropriately arranging the flow path and function parts acting on the flow path. 
     However, Japanese Patent Laid-Open No. 2011-240628 has not disclosed the configuration or arrangement relating to the flow path and the function parts for improving the compactness such as this. 
     Consequently, in view of the above-described problem, an object of the present invention is to provide an ink jet printing apparatus whose compactness is improved by appropriately configuring a flow path relating to ink, which connects a tank and a print head, and appropriately arranging the flow path and function parts acting on the flow path. 
     The present invention is an ink jet printing apparatus including: a print head that ejects ink; an ink tank for each ink color that stores the ink; an ink flow path plate for each ink color provided under the ink tank in the direction of gravity and having a supply flow path that guides the ink supplied from the ink tank to the print head and a recovery flow path that guides the ink recovered from the print head to the ink tank; a flow path concentration plate in which the supply flow path and the recovery flow path for each ink color are concentrated and which guides the ink between the ink flow path plate and the print head; and one or a plurality of function parts provided within a range of a space demarcated by the ink flow path plate and the flow path concentration plate having an inclination with respect to the ink flow path plate, and which acts on at least one of the supply flow path and the recovery flow path inside the ink flow path plate. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram in a case where a printing apparatus is in a standby state; 
         FIG. 2  is a control configuration diagram of the printing apparatus; 
         FIG. 3  is a diagram in a case where the printing apparatus is in a printing state; 
         FIG. 4  is a diagram in a case where the printing apparatus is in a maintenance state; 
         FIG. 5  is a diagram explaining a flow path configuration of an ink circulation system; 
         FIG. 6A  and  FIG. 6B  are diagrams explaining an ejection port and a pressure chamber; 
         FIG. 7A  and  FIG. 7B  are each a perspective diagram of an ink tank unit and an ink supply unit; 
         FIG. 8A  and  FIG. 8B  are each a perspective diagram of a sub unit; 
         FIG. 9A  and  FIG. 9B  are diagrams explaining the ink supply unit; 
         FIG. 10  is an enlarged diagram of a connection portion between an ink flow path plate and a flow path concentration plate; 
         FIG. 11A  to  FIG. 11C  are perspective diagrams explaining a configuration of the ink flow path plate; 
         FIG. 12  is a perspective diagram explaining a configuration of the sub unit; 
         FIG. 13  is a perspective diagram explaining arrangement of the flow path concentration plate in the ink tank unit and the ink supply unit; and 
         FIG. 14A  and  FIG. 14B  are diagrams explaining an internal configuration of the flow path concentration plate. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following, embodiments of the present invention are explained with reference to the drawings. However, the following embodiments are not intended to limit the present invention and all combinations of features explained in the present embodiments are not necessarily indispensable to the solution of the present invention. Explanation is given by attaching the same symbol to the same configuration. The relative arrangement, shapes, and so on of components described in the embodiments are merely exemplary and not intended to limit the scope of the invention only to those. 
     First Embodiment 
       FIG. 1  is an internal configuration diagram of an ink jet printing apparatus  1  (hereinafter, printing apparatus  1 ) used in the present embodiment. In  FIG. 1 , the x-direction indicates the horizontal direction, the y-direction (direction perpendicular to the paper surface) indicates the direction in which ejection ports are arrayed in a print head  8 , to be described later, and the z-direction indicates the vertical direction (direction of gravity), respectively. 
     The printing apparatus  1  is a multi function printer including a print unit  2  and a scanner unit  3  and capable of performing a variety of kinds of processing relating to the printing operation and the reading operation by the print unit  2  and the scanner unit  3  individually, or in an interlocking manner of the print unit  2  and the scanner unit  3 . The scanner unit  3  includes an ADF (Auto Document Feeder) and an FBS (Flat Bed Scanner) and is capable of reading of a document automatically fed by the ADF and reading (scanning) of a document placed on a document table of the FBS by a user. The present embodiment is the multi function printer having both the print unit  2  and the scanner unit  3 , but the multi function printer may be an aspect in which the scanner unit  3  is not included.  FIG. 1  shows a case where the printing apparatus  1  is in a standby state where the printing apparatus  1  is performing neither the printing operation nor the reading operation. 
     In the print unit  2 , at the bottom in the vertically downward direction of a casing  4 , a first cassette  5 A and a second cassette  5 B for storing a printing medium (cut sheet) S are installed in an attachable and detachable manner. In the first cassette  5 A, comparatively small printing media up to the A4 size, and in the second cassette  5 B, comparatively large printing media up to the A3 size are stored in a piled-up manner. In the vicinity of the first cassette  5 A, a first feed unit  6 A for feeding stored printing media by separating one by one is provided. Similarly, in the vicinity of the second cassette  5 B, a second feed unit  6 B is provided. In a case where the printing operation is performed, the printing medium S is selectively fed from one of the cassettes. 
     A conveyance roller  7 , a discharge roller  12 , a pinch roller  7   a , a spur  7   b , a guide  18 , an inner guide  19 , and a flapper  11  are conveyance mechanisms for guiding the printing medium S in a predetermined direction. The conveyance roller  7  is arranged on the upstream side and on the downstream side of the print head  8  and is a drive roller that is driven by a conveyance motor, not shown schematically. The pinch roller  7   a  is a follower roller that nips and rotates the printing medium S together with the conveyance roller  7 . The discharge roller  12  is arranged on the downstream side of the conveyance roller  7  and is a drive roller that is driven by a conveyance motor, not shown schematically. The spur  7   b  sandwiches and conveys the printing medium S together with the conveyance roller  7  arranged on the downstream side of the print head  8  and the discharge roller  12 . 
     The guide  18  is provided in the conveyance path of the printing medium S and guides the printing medium S in a predetermined direction. The inner guide  19  is a member extending in the y-direction and has a curved side surface, and guides the printing medium S along the side surface. The flapper  11  is a member for switching directions in which the printing medium S is conveyed at the time of the both-side printing operation. A discharge tray  13  is a tray for loading and holding the printing medium S for which the printing operation has been completed and which is discharged by the discharge roller  12 . 
     The print head  8  of the present embodiment is a color ink jet print head of full line type and in which a plurality of ejection ports from which ink is ejected in accordance with print data is arrayed along the y-direction in  FIG. 1  so as to correspond to the width of the printing medium S. In a case where the print head  8  is at the standby position, an ejection port surface  8   a  of the print head  8  faces in the vertically downward direction and is capped by a cap unit  10  as shown in  FIG. 1 . In a case where the printing operation is performed, by a print controller  202 , to be described later, the direction of the print head  8  is changed so that the ejection port surface  8   a  faces a platen  9 . The platen  9  is configured by a flat plate extending in the y-direction and supports the printing medium S from the rear side, for which the printing operation is performed by the print head  8 . The movement of the print head  8  from the standby position to the printing position will be described later in detail. 
     An ink tank unit  14  stores four color inks to be supplied to the print head  8 , respectively. An ink supply unit  15  is provided on the way in the flow path connecting the ink tank unit  14  and the print head  8  and adjusts the pressure and the amount of flow of the ink within the print head  8  to an appropriate range. In the present embodiment, a circulation-type ink supply system is adopted and the ink supply unit  15  adjusts the pressure of the ink supplied to the print head  8  and the amount of flow of the ink recovered from the print head  8  to an appropriate range. 
     A maintenance unit  16  includes the cap unit  10  and a wiping unit  17  and performs the maintenance operation for the print head  8  by causing these units to operate at predetermined timing. 
       FIG. 2  is a block diagram showing a control configuration in the printing apparatus  1 . The control configuration mainly includes a print engine unit  200  configured to centralizedly control the print unit  2 , a scanner engine unit  300  configured to centralizedly control the scanner unit  3 , and a controller unit  100  configured to centralizedly control the entire printing apparatus  1 . The print controller  202  controls various mechanisms of the print engine unit  200  in accordance with instructions of a main controller  101  of the controller unit  100 . Various mechanisms of the scanner engine unit  300  are controlled by the main controller  101  of the controller unit  100 . In the following, details of the control configuration are explained. 
     In the controller unit  100 , the main controller  101  including a CPU controls the entire printing apparatus  1  by using a RAM  106  as a work area in accordance with programs and various parameters stored in a ROM  107 . For example, in a case where a print job is input from a host apparatus  400  via a host I/F  102  or a wireless I/F  103 , predetermined image processing is performed for image data received by an image processing unit  108  in accordance with instructions of the main controller  101 . Then, the main controller  101  transmits the image data for which image processing has been performed to the print engine unit  200  via a print engine I/F  105 . 
     The printing apparatus  1  may acquire image data from the host apparatus  400  via wireless communication or wired communication or may acquire image data from an external storage device (USB memory and the like) connected to the printing apparatus  1 . The communication method that is made use of for wireless communication or wired communication is not limited. For example, as the communication method that is made use of for wireless communication, it is possible to apply Wi-Fi (Wireless Fidelity) (registered trademark) and Bluetooth (registered trademark). Further, as the communication method that is made use of for wired communication, it is possible to apply USB (Universal Serial Bus) and the like. Furthermore, for example, in a case where a read command is input from the host apparatus  400 , the main controller  101  transmits this command to the scanner unit  3  via a scanner engine I/F  109 . 
     An operation panel  104  is a mechanism for a user to input and output for the printing apparatus  1 . It is possible for a user to give instructions as to the operation, such as copy and scan, to set a printing mode, to recognize information on the printing apparatus  1 , and so on via the operation panel  104 . 
     In the print engine unit  200 , the print controller  202  including a CPU controls various mechanisms included in the print unit  2  by using a RAM  204  as a work area in accordance with programs and various parameters stored in a ROM  203 . In a case where various commands and image data are received via a controller I/F  201 , the print controller  202  temporarily stores them in the RAM  204 . The print controller  202  causes an image processing controller  205  to convert the saved image data into print data so that the print head  8  can make use of for the printing operation. In a case where print data is generated, the print controller  202  causes the print head  8  to perform the printing operation based on the print data via a head I/F  206 . At this time, the print controller  202  conveys the printing medium S by driving the feed units  6 A and  6 B, the conveyance roller  7 , the discharge roller  12 , and the flapper  11  shown in  FIG. 1  via a conveyance control unit  207 . In accordance with instructions of the print controller  202 , the printing operation by the print head  8  is performed in an interlocking manner with the conveyance operation of the printing medium S and thus printing processing is performed. 
     A head carriage control unit  208  changes the direction and position of the print head  8  in accordance with the operating state, such as the maintenance state and the printing state, of the printing apparatus  1 . An ink supply control unit  209  controls the ink supply unit  15  so that the pressure of the ink to be supplied to the print head  8  is adjusted within an appropriate range. A maintenance control unit  210  controls the operation of the cap unit  10  and the wiping unit  17  in the maintenance unit  16  at the time of performing the maintenance operation for the print head  8 . 
     In the scanner engine unit  300 , the main controller  101  controls hardware resources of a scanner controller  302  by using the RAM  106  as a work area in accordance with programs and various parameters stored in the ROM  107 . Due to this, various mechanisms included in the scanner unit  3  are controlled. For example, by the main controller  101  controlling the hardware resources within the scanner controller  302  via a controller I/F  301 , a document mounted on the ADF by a user is conveyed via a conveyance control unit  304  and read by a sensor  305 . Then, the scanner controller  302  saves the read image data in a RAM  303 . It is possible for the print controller  202  to cause the print head  8  to perform the printing operation based on the image data read by the scanner controller  302  by converting the image data acquired as described above into print data. 
       FIG. 3  shows a case where the printing apparatus  1  is in the printing state. Compared to the standby state shown in  FIG. 1 , the cap unit  10  separates from the ejection port surface  8   a  of the print head  8  and the ejection port surface  8   a  faces the platen  9 . In the present embodiment, the plane of the platen  9  is inclined about 45 degrees with respect to the horizontal direction and the ejection port surface  8   a  of the print head  8  at the printing position is also inclined about 45 degrees with respect to the horizontal direction so that the distance from the platen  9  is kept constant. 
     At the time of moving the print head  8  from the standby position shown in  FIG. 1  to the printing position shown in  FIG. 3 , the print controller  202  lowers the cap unit  10  down to the evacuate position shown in  FIG. 3  by using the maintenance control unit  210 . Due to this, the ejection port surface  8   a  of the print head  8  separates from a cap member  10   a . After this, the print controller  202  rotates the print head  8  by 45 degrees while adjusting the height in the vertical direction of the print head  8  by using the head carriage control unit  208  and causes the ejection port surface  8   a  to face the platen  9 . In a case where the printing operation is completed and the print head  8  moves from the printing position to the standby position, the process opposite to that described above is performed by the print controller  202 . 
       FIG. 4  is a diagram in a case where the printing apparatus  1  is in a maintenance state. At the time of moving the print head  8  from the standby position shown in  FIG. 1  to a maintenance position shown in  FIG. 4 , the print controller  202  moves the cap unit  10  in the vertically downward direction as well as moving the print head  8  in the vertically upward direction. Then, the print controller  202  moves the wiping unit  17  from the evacuate position in the rightward direction in  FIG. 4 . After this, the print controller  202  moves the print head  8  to the maintenance position at which the maintenance operation is possible by moving the print head  8  in the vertically downward direction. 
     On the other hand, in a case of moving the print head  8  from the printing position shown in  FIG. 3  to the maintenance position shown in  FIG. 4 , the print controller  202  moves the print head  8  in the vertically upward direction while rotating the print head  8  by 45 degrees. Then, the print controller  202  moves the wiping unit  17  from the evacuate position in the rightward direction. After this, the print controller  202  moves the print head  8  to the maintenance position at which the maintenance operation by the maintenance unit  16  is possible by moving the print head  8  in the vertically downward direction. 
     &lt;Ink Supply Unit (Ink Circulation System)&gt; 
       FIG. 5  is a diagram including the ink supply unit  15  adopted in the ink jet printing apparatus  1  of the present embodiment. By using  FIG. 5 , the flow path configuration of the ink circulation system of the present embodiment is explained. The ink supply unit  15  supplies ink supplied from the ink tank unit  14  to the print head  8  (head unit). In  FIG. 5 , the configuration of one color ink is shown, but actually, such a configuration is prepared for each ink color (for example, for each of cyan (C), magenta (M), yellow (Y), black (Bk)). The ink supply unit  15  is controlled basically by the ink supply control unit  209  shown in  FIG. 2 . In the following, each configuration of the ink supply unit  15  is explained. 
     Ink circulates mainly between a sub tank  151  and the print head  8 . In the print head  8 , the ejection operation of ink is performed based on image data and the ink that is not ejected is recovered again to the sub tank  151 . 
     The sub tank  151  that stores a predetermined amount of ink is connected to a supply flow path C 2  for supplying ink to the print head  8  and a recovery flow path C 4  for recovering ink from the print head  8 . That is, the circulation path through which ink circulates is configured by the sub tank  151 , the supply flow path C 2 , the print head  8 , and the recovery flow path C 4 . Further, the sub tank  151  is connected to an air flow path C 0  through which air flows. 
     In the sub tank  151 , a liquid surface detection unit  151   a  including a plurality of pins is provided and it is possible for the ink supply control unit  209  to grasp the height of the ink liquid surface, that is, the ink remaining amount within the sub tank  151  by detecting whether or not there is a conduction current between the plurality of pins. A decompression pump P 0  (within-tank decompression pump) is a negative pressure generation source for decompressing the inside of the sub tank  151 . An atmosphere open valve V 0  is a valve for switching whether or not to cause the inside of the sub tank  151  to communicate with the atmosphere. 
     A main tank  141  is a tank that stores ink to be supplied to the sub tank  151 . The main tank  141  has a configuration attachable to and detachable from the printing apparatus main body. On the way of a tank connection flow path C 1  that connects the sub tank  151  and the main tank  141 , a tank supply valve V 1  for switching connections of the sub tank  151  and the main tank  141  is arranged. 
     In a case of detecting that the ink within the sub tank  151  becomes smaller than a predetermined amount by the liquid surface detection unit  151   a , the ink supply control unit  209  closes the atmosphere open valve V 0 , a supply valve V 2 , a recovery valve V 4 , and a head exchange valve V 5 , and opens the tank supply valve V 1  and a sub tank decompression valve V 6 . In this state, the ink supply control unit  209  causes the decompression pump P 0  to operate. Then, the pressure inside the sub tank  151  becomes negative and ink is supplied from the main tank  141  to the sub tank  151 . In a case of detecting that the ink within the sub tank  151  exceeds a predetermined amount by the liquid surface detection unit  151   a , the ink supply control unit  209  closes the tank supply valve V 1  and the sub tank decompression valve V 6  and suspends the decompression pump P 0 . 
     The supply flow path C 2  is a flow path for supplying ink from the sub tank  151  to the print head  8  and on the way thereof, a supply pump P 1  and the supply valve V 2  are arranged. During the printing operation, by driving the supply pump P 1  in the state where the supply valve V 2  is open, it is possible to circulate ink in the circulation path while supplying ink to the print head  8 . The amount of ink ejected per unit time by the print head  8  fluctuates in accordance with image data. The amount of flow of the supply pump P 1  is determined so as to be compatible also with a case where the print head  8  performs the ejection operation that maximizes the amount of ink to be consumed per unit time. Further, in the supply flow path C 2 , a check valve V 7  that prevents a backflow of ink to the sub tank  151  is arranged. The check valve V 7  is a valve that permits a flow of ink in one direction. 
     A relief flow path C 3  is a flow path that is located on the upstream side of the supply valve V 2  and which connects the upstream side and the downstream side of the supply pump P 1 . On the way of the relief flow path C 3 , a relief valve V 3 , which is a differential pressure valve, is arranged. The relief valve is not opened and closed by a drive mechanism, but is biased by a spring and configured so as to open in a case where a predetermined pressure is reached. For example, in a case where the ink supply amount per unit time from the supply pump P 1  is larger than the total value of the ejection amount per unit time of the print head  8  and the flow amount (amount of ink to be drawn) per unit time of the recovery pump P 2 , the relief valve V 3  is opened in accordance with the pressure that is exerted on the relief valve V 3  itself. Due to this, a circulation path configured by a part of the supply flow path C 2  and the relief flow path C 3  is formed. By providing the configuration of the relief flow path C 3 , the ink supply amount for the print head  8  is adjusted in accordance with the ink consumption in the print head  8 , and therefore, it is possible to stabilize the pressure within the circulation path irrespective of image data. 
     The recovery flow path C 4  is a flow path for recovering ink from the print head  8  to the sub tank  151  and on the way thereof, a recovery pump P 2 , the recovery valve V 4 , a suction valve V 8 , and check valves V 9  and V 10  are arranged. In the recovery flow path C 4 , buffer chambers B 1  and B 2  are further arranged. At the time of circulating ink within the circulation path, the recovery pump P 2  functions as a negative pressure generation source to suck ink from the print head  8 . By the drive of the recovery pump P 2 , an appropriate pressure difference arises between an IN flow path  80   b  and an OUT flow path  80   c  within the print head  8 , and therefore, it is possible to circulate ink between the IN flow path  80   b  and the OUT flow path  80   c . The flow path configuration within the print head  8  will be described later in detail. 
     The check valve V 9  and the check valve V 10  are each a valve that prevents a backflow of ink to the print head  8 . In the present embodiment, two check valves are provided preliminarily. The recovery valve V 4  is also a valve for preventing a backflow in a case where the printing operation is not being performed, that is, ink is not being circulated within the circulation path. In the circulation path of the present embodiment, the sub tank  151  is arranged above the print head  8  in the vertical direction (see  FIG. 1 ). Because of this, in a case where the supply pump P 1  and the recovery pump P 2  are not driven, there is a possibility that ink flows backward to the print head  8  from the sub tank  151  due to a water head difference between the sub tank  151  and the print head  8 . In order to prevent such a backflow, in the present embodiment, the check valve V 9 , the check valve V 10 , and the recovery valve V 4  are provided in the recovery flow path C 4 . 
     The supply valve V 2  also functions as a valve for preventing supply of ink to the print head  8  from the sub tank  151  in a case where the printing operation is not being performed, that is, ink is not being circulated within the circulation path. 
     The suction valve V 8  is controlled by the ink supply control unit  209  so as to close at the time of the suction operation being performed by capping the print head  8  by the cap unit  10  (not shown schematically in  FIG. 5 ). The reason is to prevent the ink within the flow path from being sucked into the cap unit  10  more than necessary at the time of suction. At the time of suction, the supply valve V 2  and the head exchange valve V 5  are also controlled by the ink supply control unit  209  so as to close. 
     The buffer chambers B 1  and B 2  are parts for reducing the influence of expansion and contraction of air bubbles in the ink within the flow path. The buffer chambers B 1  and B 2  include a compression spring and a flexible member, such as a film, and the film expands and contracts as the compression spring expands and contracts. In a case where the air bubbles in the ink within the flow path expand and contract due to a change in temperature or the like in the state where ink is not circulating, the buffer chambers B 1  and B 2  expand and contract following a change in volume of the air bubbles in the flow path. Due to this, it is possible to prevent ink leakage at the ejection port and drawing of air from the ejection port, which result from a change in the pressure exerted on the ejection port by the air bubbles expanding and contracting. In the present embodiment, the two buffer chambers B 1  and B 2  are provided for expansion and contraction, respectively. 
     A head exchange flow path C 5  is a flow path that connects the supply flow path C 2  and an air chamber (space in which ink is not stored) of the sub tank  151  and on the way thereof, the head exchange valve V 5  is arranged. One end of the head exchange flow path C 5  is connected to the upstream of the print head  8  in the supply flow path C 2  and connected to the downstream side of the supply valve V 2 . The other end of the head exchange flow path C 5  connects to the upper portion of the sub tank  151  in the direction of gravity and communicates with the air chamber inside the sub tank  151 . The head exchange flow path C 5  is made use of in a case where ink is drawn from the print head  8  in use at the time of exchanging the print head  8  or transporting the printing apparatus  1 . The head exchange valve V 5  is controlled by the ink supply control unit  209  so as to close except for a case where the print head  8  is filled with ink and a case where ink is drawn from the print head  8 . 
     Next, the flow path configuration within the print head  8  is explained. The ink supplied to the print head  8  by the supply flow path C 2  is supplied to a first negative pressure control unit  81  and a second negative pressure control unit  82  after passing through a filter  83 . The control pressure of the first negative pressure control unit  81  is set to a weak negative pressure (negative pressure whose difference in pressure from the atmospheric pressure is small). The control pressure of the second negative pressure control unit  82  is set to a strong negative pressure (negative pressure whose difference in pressure from the atmospheric pressure is large). The pressures in the first negative pressure control unit  81  and the second negative pressure control unit  82  are generated in an appropriate range by the drive of the recovery pump P 2 . 
     In an ink ejection unit  80 , a plurality of printing element substrates  80   a  on which a plurality of ejection ports is arrayed is arranged and a long ejection port row is formed. The common supply flow path  80   b  (IN flow path) for guiding ink supplied by the first negative pressure control unit  81  and the common recovery flow path  80   c  (OUT flow path) for guiding ink supplied by the second negative pressure control unit  82  are also extending in the array direction of the printing element substrate  80   a . Further, on the individual printing element substrate  80   a , an individual supply flow path connected with the common supply flow path  80   b  and an individual recovery flow path connected with the common recovery flow path  80   c  are formed. Because of this, on the individual printing element substrate  80   a , a flow of ink is generated, which flows in from the common supply flow path  80   b  where the negative pressure is relatively weak and flows out to the common recovery flow path  80   c  where the negative pressure is relatively strong. In the path between the individual supply flow path and the individual recovery flow path, a pressure chamber that communicates with each ejection port and which is filled with ink is provided and also in the ejection port or the pressure chamber not performing printing, a flow of ink is generated. In a case where the ejection operation is performed on the printing element substrate  80   a , a part of the ink that moves from the common supply flow path  80   b  to the common recovery flow path  80   c  is consumed by being ejected from the ejection port, but the ink that is not ejected moves to the recovery flow path C 4  via the common recovery flow path  80   c.    
       FIG. 6A  is a schematic plan diagram showing an enlarged part of the printing element substrate  80   a  and  FIG. 6B  is a schematic sectional diagram along a section line VIB-VIB in  FIG. 6A . The printing element substrate  80   a  is provided with a pressure chamber  1005  filled with ink and an ejection port  1006  through which ink is ejected. In the pressure chamber  1005 , at a position in opposition to the ejection port  1006 , a printing element  1004  is provided. Further, on the printing element substrate  80   a , an individual supply flow path  1008  that connects with the common supply flow path  80   b  and an individual recovery flow path  1009  that connects with the common recovery flow path  80   c  are formed in plurality for each ejection port  1006 . 
     By the configuration described above, on the printing element substrate  80   a , a flow of ink is generated, which flows in from the common supply flow path  80   b  where the negative pressure is relatively weak (absolute value of pressure is high) and flows out to the common recovery flow path  80   c  where the negative pressure is relatively strong (absolute value of pressure is low). In more detail, ink flows in the order of the common supply flow path  80   b →the individual supply flow path  1008 →the pressure chamber  1005 →the individual recovery flow path  1009 →the common recovery flow path  80   c . In a case where ink is ejected by the printing element  1004 , a part of the ink that moves from the common supply flow path  80   b  to the common recovery flow path  80   c  is discharged to the outside of the print head  8  by being ejected from the ejection port  1006 . On the other hand, the ink that is not ejected from the ejection port  1006  is recovered to the recovery flow path C 4  via the common recovery flow path  80   c.    
     In a case where the printing operation is performed, the ink supply control unit  209  closes the tank supply valve V 1 , the head exchange valve V 5 , and the sub tank decompression valve V 6 , opens the atmosphere open valve V 0 , the supply valve V 2 , the recovery valve V 4 , and the suction valve V 8 , and drives the supply pump P 1  and the recovery pump P 2 . Due to this, a circulation path of the sub tank  151 →the supply flow path C 2 ,→the print head  8 →the recovery flow path C 4 →the sub tank  151  is established. In a case where the ink supply amount per unit time from the supply pump P 1  is larger than the total value of the ejection amount per unit time of the print head  8  and the flow amount per unit time in the recovery pump P 2 , ink flows into the relief flow path C 3  from the supply flow path C 2 . Due to this, the flow amount of ink that flows into the print head  8  from the supply flow path C 2  is adjusted. 
     In a case where the printing operation is not being performed, the ink supply control unit  209  suspends the supply pump P 1  and the recovery pump P 2  and closes the atmosphere open valve V 0 , the supply valve V 2 , the recovery valve V 4 , and the suction valve V 8 . Due to this, the flow of ink within the print head  8  suspends and a backflow due to the water head difference between the sub tank  151  and the print head  8  is also suppressed. Further, by closing the atmosphere open valve V 0 , leakage of ink and evaporation of ink from the sub tank  151  are suppressed. 
     In a case where ink is drawn from the print head  8 , the ink supply control unit  209  closes the atmosphere open valve V 0 , the tank supply valve V 1 , the supply valve V 2 , the recovery valve V 4 , and the suction valve V 8 , opens the head exchange valve V 5 , and drives the decompression pump P 0 . Due to this, the inside of the sub tank  151  enters a negative pressure state and the ink within the print head  8  is recovered to the sub tank  151  via the head exchange flow path C 5 . As described above, the head exchange valve V 5  is a valve that is closed at the time of the normal printing operation and the standby and opened at the time of drawing ink from the print head  8 . The head exchange valve V 5  is also opened at the time of filling the head exchange flow path C 5  with ink in a case where the print head  8  is filled with ink. 
     &lt;Ink Supply Unit&gt; 
       FIG. 7A  and  FIG. 7B  are perspective diagrams including the ink tank unit  14  and the ink supply unit  15 . From the main tank  141  of each color of the ink tank unit  14 , ink is supplied to the ink supply unit  15  via a supply tube  142 . That is, within the supply tube  142 , the tank connection flow path C 1  that supplies ink from the main tank  141  to the sub tank  151  is formed. As shown in  FIG. 7B , the ink supply unit  15  is arranged under the ink tank unit  14  in the direction of gravity. Hereinafter, in a case where “above” and “under” are simply referred to, it is assumed that “above” and “under” in the direction of gravity (z-direction) are meant. The arrangement configuration of the ink supply unit  15  will be described later. In the ink supply unit  15 , a linking tube  159  is provided for each of the supply flow path C 2  and the recovery flow path C 4 . The inside of the linking tube  159  is divided into flow paths corresponding to each color ink. That is, within a linking tube  159   a  on one hand, the supply flow paths C 2  corresponding to each color are formed and within a linking tube  159   b  on the other hand, the recovery flow paths C 4  corresponding to each color are formed. The linking tubes  159   a  and  159   b  are connected to the print head  8  (not shown schematically in  FIG. 7A  and  FIG. 7B ). At the upper portion of the ink supply unit  15 , an atmosphere communication plate  154  is arranged. 
       FIG. 8A  is a perspective diagram of a sub unit  150  configuring the ink supply unit  15 .  FIG. 8B  is a perspective diagram in a state where the atmosphere communication plate  154  in  FIG. 8A  is separated from the sub unit  150 . The sub unit  150  is provided for each ink color. Here, the sub unit  150  corresponding to an arbitrary ink color is shown. The sub unit  150  includes the sub tank  151 , an ink flow path plate  152  arranged under the sub tank  151 , and the atmosphere communication plate  154  arranged above the sub tank  151 . On the ink flow path plate  152 , a tube connection portion  1511  that connects the supply tube  142  (see  FIG. 7A  and  FIG. 7B ) connected to the main tank  141  is arranged. Ink is supplied to the sub tank  151  through the tank connection flow path C 1  formed within the ink flow path plate  152 . Further, within the ink flow path plate  152 , the supply flow path C 2  through which ink is supplied from the sub tank  151  to the print head  8  and the recovery flow path C 4  through which ink is recovered to the sub tank  151  from the print head  8  are formed. Within the atmosphere communication plate  154 , the air flow path C 0  through which air flows is formed. 
     As shown in  FIG. 8A  and  FIG. 8B , in the present embodiment, above the ink flow path plate  152 , the sub tank  151  and one or a plurality of function parts (referred to as a first function part group  153 ) are arranged. The first function part group  153  is a general term of function parts that act on the ink flow path. The function parts included in the first function part group  153  are, for example, the drive valve for opening and closing the flow path by a drive mechanism, the differential pressure valve, the check valve, the circulation pump used for circulation (supply pump P 1 , recovery pump P 2 ), and the buffer chambers B 1  and B 2 . The drive valve included in the first function part group  153  is, for example, the tank supply valve V 1 , the supply valve V 2 , the recovery valve V 4 , the head exchange valve V 5 , and the suction valve V 8 . The differential pressure valve included in the first function part group  153  is, for example, the relief valve V 3 . The check valve is one kind of differential pressure valve and the check valve V 7 , the check valve V 9 , and the check valve V 10  are also included in the differential pressure valve. As described above, the first function part group  153  includes the function parts that act on the tank connection flow path C 1 , the supply flow path C 2 , the relief flow path C 3 , the recovery flow path C 4 , or the head exchange flow path C 5 . The connection portion of the supply flow path C 2  and the relief flow path C 3  and the connection portion of the supply flow path C 2  and the head exchange flow path C 5  are provided within the ink flow path plate  152  (not shown schematically). 
     Under the atmosphere communication plate  154 , one or a plurality of function parts (referred to as a second function part group  155 ) is arranged. The second function part group  155  is a general term of function parts that act on the air flow path. The function parts included in the second function part group  155  are, for example, the drive valve for opening and closing the flow path by a drive mechanism. The drive valve is, for example, the atmosphere open valve V 0  and the sub tank decompression valve V 6 . As described above, the second function part group  155  includes the function parts that act on the air flow path C 0 . 
     The sub tank  151 , the ink flow path plate  152 , the atmosphere communication plate  154 , the first function part group  153 , and the second function part group  155  shown in  FIG. 8A  and  FIG. 8B  are provided for each ink color. In the present embodiment, it is possible to make the configuration of each of the main tank  141 , the sub tank  151 , the ink flow path plate  152 , the atmosphere communication plate  154 , the first function part group  153 , and the second function part group  155  common to all the ink colors. By making the configuration of the sub unit  150  common to all the ink colors, it is possible to reduce the cost of the sub unit  150  compared to a case where the configuration of the sub unit  150  is prepared for each ink color. The function parts included in the first function part group  153  and the second function part group  155  are merely exemplary and it may also be possible to exclude part of the function parts or to include another function part other than those described above. 
       FIG. 9A  is a perspective diagram of the ink supply unit  15 . The ink supply unit  15  includes a longitudinally-installed flow path concentration plate  156  for concentrating the flow paths for each sub unit  150 , in addition to the sub unit  150  for each ink color. In this example, the flow path concentration plate  156  and the four sub units  150  are arranged so as to be included within the xy-plane demarcated by a supply pan  157 . Further, a plurality of the sub units  150  having the same arrangement configuration is arranged side by side in the y-direction, facing in the same direction. 
       FIG. 9B  is a perspective diagram of a part of the ink supply unit  15  (specifically, only the sub unit  150  corresponding to one color and the flow path concentration plate  156  are shown). The sub tank  151  is arranged approximately above one end portion of the ink flow path plate  152 . That is, a connection portion (hereinafter, referred to as a first connection portion  1512 , see  FIG. 11C  also) of the sub tank  151  and the ink flow path plate  152  is provided on the undersurface of the sub tank  151 . Within the ink flow path plate  152 , the flow paths (supply flow path C 2  and recovery flow path C 4 ) are formed so as to extend in the horizontal direction (in detail, x-direction) from the first connection portion  1512  that connects with the sub tank  151 . The flow path extends in the x-direction as a whole and may be guided in another direction on the way. On the other end portion on the opposite side in the x-direction of the end portion on which the first connection portion  1512  of the ink flow path plate  152  is provided, a connection portion (hereinafter, referred to as a second connection portion  1561 ) that connects the flow path within the ink flow path plate  152  to the flow path within the flow path concentration plate  156  is provided. 
     The flow path concentration plate  156  is arranged above the ink flow path plate  152  of each sub unit  150  so as to traverse each second connection portion  1561 . Within the flow path concentration plate  156 , a flow path that guides ink to be sent to each second connection portion  1561  or ink to be sent from each second connection portion  1561  approximately in the y-direction (approximately parallel to the direction in which the ink flow path plates  152  are arranged side by side) is formed (see  FIG. 14A  also). As shown in  FIG. 9B , within the flow path concentration plate  156 , the flow paths of all the ink colors are arranged one on top of another in the z-direction. The flow path concentration plate  156  includes a third connection portion  1591  that connects with the linking tube  159  (see  FIG. 7A  and  FIG. 7B ). 
     As described above, the supply flow path C 2  and the recovery flow path C 4  are formed inside the ink flow path plate  152  for each ink color, the flow path concentration plate  156  used in common for all the ink colors, and the linking tube  159 . 
       FIG. 10  is an enlarged diagram of the connection portion of the ink flow path plate  152  and the flow path concentration plate  156  in  FIG. 9B . The two plates perpendicular to each other, that is, the ink flow path plate  152  extending in the xy-direction (horizontal direction) and the flow path concentration plate  156  extending in the yz-direction (direction of plane including the direction of gravity) are screwed by screws  1562 . The reason the flow path concentration plate  156  is provided in the present embodiment is as follows. At the time of providing a flow path relating to ink for guiding ink between the sub tank  151  and the print head  8 , in a case where the entire section is provided for each ink color, the cost is raised. Because of this, in the present embodiment, the linking tube  159  that concentrates the flow paths for each ink color is adopted. However, in order to make use of the linking tube  159 , it is necessary to put together the flow paths for each ink color. In a case where it is attempted to put together the flow paths for each ink color within the same plane as that of the ink flow path plate  152  under the sub tank  151 , a plate for putting together the flow paths, which extends in the xy-direction, becomes further necessary, and therefore, the ink supply unit becomes large in the xy-direction. As a result of this, it becomes difficult to implement downsizing of the ink supply unit. Because of this, in the present embodiment, the flow path concentration plate  156  perpendicular to the ink flow path plate  152  is provided and the inside of a space demarcated by the ink flow path plate  152  and the flow path concentration plate  156  is effectively made use of while concentrating the flow paths for each ink color within the flow path concentration plate  156 . Specifically, the space is made use of as a space in which the first function part group  153  is arranged. Due to this, downsizing of the ink supply unit  15  is implemented. 
     As described above, it is possible to make the ink supply unit  15  compact by providing the flow path concentration plate  156  perpendicular to the ink flow path plate  152  and forming the ink supply unit  15  so that the flow path of ink does not become large in the xy-direction. 
     &lt;Ink Flow Path Plate&gt; 
       FIG. 11A  to  FIG. 11C  are perspective diagrams explaining the configuration of the ink flow path plate  152 .  FIG. 11A  is a diagram in a case where the ink flow path plate  152  is viewed from under.  FIG. 11B  is a diagram in which the film member on the surface in  FIG. 11A  is made transparent so that the flow paths become visible.  FIG. 11C  is a diagram in a case where the ink flow path plate  152  is viewed from above.  FIG. 11C  shows a diagram in the state where the sub tank  151  and the first function part group  153  arranged on the ink flow path plate  152  are separated. 
       FIG. 12  is a perspective diagram in which the sub tank  151  and the first function part group  153  are arranged on the ink flow path plate  152 . In  FIG. 12 , the parts corresponding to the drive valve, the differential pressure valve, the check valve, the buffer chamber, and the circulation pump shown in  FIG. 5  are shown with the same symbols as those in  FIG. 5 . As shown in  FIG. 12 , the first function part group  153  is arranged above the ink flow path plate  152 . The first function part group  153  is the parts that perform control of opening and closing of a flow path and control of the amount of flow of ink flowing through a flow path. Because of this, the first function part group  153  is arranged above the position corresponding to the flow path formed within the ink flow path plate  152 . As described above, in the present embodiment, the first function part group  153  that acts on the flow paths relating to the flow of ink (tank connection flow path C 1 , supply flow path C 2 , relief flow path C 3 , recovery flow path C 4 , and head exchange flow path C 5 ) is concentrated and arranged above the ink flow path plate  152 . 
     &lt;Flow Path Concentration Plate&gt; 
       FIG. 13  is a perspective diagram showing the arrangement of the flow path concentration plate  156  in the ink tank unit  14  and the ink supply unit  15 .  FIG. 14A  and  FIG. 14B  are diagrams showing the internal configuration of the flow path concentration plate  156 . In detail,  FIG. 14A  is a diagram showing flow paths that guide ink approximately along the y-direction in a case where the flow paths are viewed from the −x-direction. On the other hand,  FIG. 14B  is a diagram showing flow paths that guide ink along the z-direction in a case where the flow paths are viewed from the +x-direction. In  FIG. 13 ,  FIG. 14A , and  FIG. 14B , the film member on the surface of the flow path concentration plate  156  is made transparent and the flow paths are made visible. 
     The flow path concentration plate  156  extending in the yz-direction is a plate for concentrating the flow paths relating to ink within the sub unit  150  for each ink color and connecting to the linking tubes  159   a  and  159   b . The flow path concentration plate  156  has a third connection portion  1591   a  that connects with the linking tube  159   a  and a third connection portion  1591   b  that connects with the linking tube  159   b . The flow paths formed within the ink flow path plate  152  in the sub unit  150  for each ink color are connected with the flow paths formed within the flow path concentration plate  156  via the second connection portion  1561 . 
     As shown in  FIG. 14A  and  FIG. 14B , within the flow path concentration plate  156 , eight flow paths that guide ink are formed. The details of the eight flow paths are four supply flow paths that convey each color ink from the sub tank  151  for each ink color to the print head  8  and four recovery flow paths that convey each color ink from the print head  8  to the sub tank  151  for each ink color. Each of the four supply flow paths within the flow path concentration plate  156  is configured by a portion (referred to as a supply flow path  1563 ) that guides ink approximately along the y-direction and a portion (referred to as a supply flow path  1564 ) that guides ink along the z-direction. Similarly, each of the four recovery flow paths within the flow path concentration plate  156  is configured by a portion (referred to as a recovery flow path  1565 ) that guides ink along the z-direction and a portion (referred to as a recovery flow path  1566 ) that guides ink approximately along the y-direction. 
     With the configuration such as this, ink flows in the order of the sub tank  151 →the supply flow path within the ink flow path plate  152 →the supply flow path  1563 →the supply flow path  1564 →the linking tube  159   a →the print head  8  and the ink is supplied to the print head  8 . Then, the ink not used for printing flows in the order of the print head  8 →the linking tube  159   b →the recovery flow path  1565 →the recovery flow path  1566 →the recovery flow path within the ink flow path plate  152  and recovered to the sub tank  151 . 
     Effect of the Present Embodiment, Modification Example and the Like 
     As explained above, the plurality of the ink flow path plates  152  having the same configuration is arranged side by side in the y-direction, facing in the same direction and the flow path concentration plate  156  is arranged across the plurality of the ink flow path plates  152  (see  FIG. 9A ). Further, in each sub unit  150 , the first function part group  153  that acts on the flow paths of ink within the ink flow path plate  152  is arranged so as to be included within a space demarcated by the ink flow path plate  152  and the flow path concentration plate  156 . Specifically, the first function part group  153  is arranged above the ink flow path plate  152  and between the sub tank  151  and the flow path concentration plate  156 . 
     As above, in the present embodiment, the flow paths within the ink supply unit  15  are implemented by using the two kinds of plates, that is, the plurality of the ink flow path plates  152  extending in the xy-direction and the flow path concentration plate  156  extending in the yz-direction. By designing the configuration such as this, it is made possible to make effective use of the space demarcated by the plurality of the ink flow path plates  152  and the flow path concentration plate  156  while suppressing the flow path from becoming large in the xy-direction of the flow path, compared to a case where only the plates extending in the xy-direction are used. Consequently, it is possible to make compact the ink supply unit and as a result of this, the printing apparatus  1  by preventing the ink supply unit  15  from becoming large in the xy-direction. Further, by arranging the first function part group  153  within the space (chamber) demarcated by the plurality of the ink flow path plates  152  and the flow path concentration plate  156 , it is made possible to protect the first function part group  153 . 
     In the explanation given previously, the example is explained in which the first function part group  153  that acts mainly on the flow path is arranged within the range of the space demarcated by the ink flow path plate  152  and the flow path concentration plate  156 , but another part may be arranged. For example, a motor, not shown schematically, for driving a drive valve and a pump, or a drive mechanism, such as a gear, may be arranged within the space. 
     Further, in the explanation given previously, the case is explained where the printing apparatus  1  includes the sub unit for each ink color (that is, the sub units of cyan (C), magenta (M), yellow (Y), and black (Bk)). However, the number of sub units is not limited to four. It is possible to apply the present invention to a printing apparatus including any number (however, two or more) of sub units. For example, a case is considered where two kinds of ink, that is, a first ink and a second ink are made use of. In this case, the printing apparatus according to the present invention includes a first ink flow path plate for the first ink, a second ink flow path plate for the second ink, and a flow path concentration plate that concentrates a supply flow path and a recovery flow path for the first ink and a supply flow path and a recovery flow path for the second ink. 
     According to the present invention, it is possible to provide an ink jet printing apparatus whose compactness is improved. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2018-066376 filed Mar. 30, 2018, which is hereby incorporated by reference herein in its entirety.