Abstract:
A differential pressure valve unit that is accommodated in a liquid cartridge main body having: a liquid containing portion containing liquid; and a liquid supply portion supplying the liquid in the liquid containing portion to the outside, the differential pressure value unit including: a membrane valve that is opened when a predetermined pressure difference between the liquid containing portion and the liquid supply portion occurs; and a first member that holds the membrane valve and forms a downstream pressure chamber together with the membrane valve, wherein, in the first member, an opposing surface forming the downstream pressure chamber and having a connection port connected to the liquid supply portion has a shape corresponding to a movable range of the membrane valve, and a groove portion is provided at the opposing surface in order to allow the liquid in the downstream pressure chamber to easily flow into the connection port.

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to a differential pressure valve unit that is accommodated in a liquid cartridge main body. In particular, the present invention relates to a structure of a differential pressure valve unit that is mounted to an ink cartridge used for an ink jet recording apparatus. 
   2. Related Art 
   In an ink jet recording apparatus, an ink cartridge that contains ink is mounted on a holder of the ink jet recording apparatus, and ink is supplied to a recording head. 
   In such an ink cartridge, a differential pressure valve unit having a valve member that is opened when a predetermined pressure difference between an ink containing portion containing ink and an ink supply portion supplying ink occurs is attached to the ink cartridge. Moreover, the ink cartridge described herein is an example of a liquid cartridge. 
   For example, a differential pressure valve unit described in Patent Document 1 has a valve member that can be elastically deformed on the basis of a pressure difference and has a cylindrical edge portion, a valve lid that has a valve member holding portion, substantially having a cylindrical shape, inserted into the edge portion of the valve member to fix the edge portion, and an urging member that is interposed between the valve member and the valve lid and urges the valve member in a direction away from the valve lid. 
   Patent Document 1: JP-A-2004-237720 
   In the above-described differential pressure valve unit of the ink cartridge, since the differential pressure valve does not normally operate when a downstream pressure chamber between a membrane valve serving as the valve member and the valve lid is empty, an ink end may be judged in a state where ink remains in the downstream pressure chamber. In a known differential pressure valve unit, a space of the downstream pressure chamber is comparatively large and, when the ink end is judged, a large amount of ink remains in the downstream pressure chamber. 
   In order to solve this problem, a method that makes the space of the downstream pressure chamber between the membrane valve and the valve lid small is considered. However, when the space of the downstream pressure chamber is made small, the flow of the liquid when the liquid is discharged from the chamber deteriorates, and thus responsibility to a pressure applied to the differential pressure valve unit may be degraded. 
   SUMMARY 
   An advantage of some aspects of the invention is to provide a differential pressure valve unit that can reduce the amount of a liquid remaining in a downstream pressure chamber of a differential pressure valve of a liquid cartridge and improve responsibility to a pressure applied to a differential pressure valve unit, and a liquid cartridge having such a differential pressure valve unit. 
   According to an aspect of the invention, there is provided a differential pressure valve unit that is accommodated in a liquid cartridge main body having: a liquid containing portion containing liquid; and a liquid supply portion supplying a liquid in the liquid containing portion to the outside. The differential pressure valve unit includes a membrane valve that is opened when a predetermined pressure difference between the liquid containing portion and the liquid supply portion occurs, and a first member that holds the membrane valve and forms a downstream pressure chamber together with the membrane valve. In the first member, an opposing surface forming the downstream pressure chamber and having a connection port connected to the liquid supply portion has a shape corresponding to a movable range of the membrane valve. A groove portion is provided at the opposing surface in order to allow the liquid in the downstream pressure chamber to easily flow into the connection port. 
   According to this configuration, when the membrane valve is opened, even though the membrane valve is deformed due to a pressure applied thereto, the interference with the first member does not occur. For this reason, the volume in the membrane valve is reduced, without obstructing the movement of the membrane valve, and thus the liquid residual quantity can be reduced. Further, a flow passage of the liquid can be secured by the groove portion, and the liquid may flow into the connection port connected to the liquid supply portion along the groove portion. Therefore, responsibility of opening/closing to the pressure of the membrane valve can be improved. 
   The groove portion may be provided such that an extension line of a center line thereof crosses the connection port. 
   According to this configuration, the liquid smoothly flows into the connection port through the groove portion. 
   The groove portion may be provided so as to cross the connection port. 
   According to this configuration, the liquid further smoothly flows from the groove portion into the connection port. 
   The first member may be substantially formed in a disc shape, and the groove portion may be provided along a diameter direction of the opposing surface. 
   According to this configuration, in the first member formed in approximately a disc shape, the liquid smoothly flows in a diameter direction of the first member. Therefore, the liquid that is distant from the connection port can be smoothly discharged. 
   The groove portion may be substantially provided in a linear shape. 
   According to this configuration, since the groove portion becomes a linear flow passage, the travel distance of the liquid toward the connection port is comparatively short. 
   The groove portion may be substantially provided in a ring shape. 
   According to this configuration, the liquid can smoothly flow over a comparatively wide range of the opposing surface. 
   A plurality of groove portions may be provided. 
   According to this configuration, a plurality of flow passages of the liquid can be secured by the plurality of groove portions. Therefore, the liquid can smoothly flow over a comparatively wide range of the opposing surface. 
   The shape corresponding to the movable range of the membrane valve may be a mortar shape having a deep central portion and a shallow peripheral portion. 
   According to this configuration, in a state where the membrane valve is opened, when the membrane valve is deformed due to the pressure applied thereto, and the central portion thereof is dented deep and the peripheral portion thereof is dented shallow, the interference with the opposing surface of the first member does not occur. Then, the volume in the membrane valve is reduced, without obstructing the movement of the membrane valve, and thus the ink residual quantity can be reduced. 
   The differential pressure valve unit according to the aspect of the invention may further include an urging member that is interposed between the membrane valve and the first member and urges the membrane valve in a direction in which the valve is closed. 
   According to this configuration, a load can be stabilized by an urging force from the urging member, the opening/closing operation of the differential pressure valve can be reliably performed, and accuracy of the pressure to be generated can be improved. 
   The first member may be a valve lid. 
   According to this configuration, when the membrane valve is opened, even though the membrane valve is deformed due to a pressure applied thereto, the interference with the first member does not occur. For this reason, the volume in the membrane valve is reduced, without obstructing the movement of the membrane valve, and thus the liquid residual quantity can be reduced. 
   The liquid cartridge may be an ink cartridge. Then, it is possible to obtain an ink cartridge having a small liquid residual quantity that is used in an ink jet recording apparatus. Then, in an ink injection process into the ink cartridge, ink is easily filled into the differential pressure valve. 
   According to the invention, since the shape of the opposing surface that forms the downstream pressure chamber of the first member corresponds to the movable range of the membrane valve, the amount of the liquid remaining in the downstream pressure chamber can be reduced. Further, since the groove portion is provided at the opposing surface in order to allow the liquid to easily flow into the connection port, the liquid in the downstream pressure chamber easily flows through the connection port, and thus responsibility to the pressure of the differential pressure valve unit can be improved. 
   In addition, with the liquid cartridge having the above-described differential pressure valve unit, for example, an ink cartridge having a small liquid residual quantity that is used in an ink jet recording apparatus can be obtained. Then, in an ink injection process into the ink cartridge, ink is easily filled into the differential pressure valve. 
   The present disclosure relates to the subject matter contained in Japanese patent application Nos. 2005-359540 filed on Dec. 13, 2005 and 2006-198555 filed on Jul. 20, 2006, which are expressly incorporated herein by reference in its entirety. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of an ink cartridge including a differential pressure valve unit according to a first embodiment of the invention. 
       FIG. 2  is a cross-sectional view of the ink cartridge shown in  FIG. 1  taken along the line II-II. 
       FIG. 3  is an enlarged cross-sectional view of the differential pressure valve unit shown in  FIG. 2 . 
       FIG. 4  is a perspective view showing a valve lid of the differential pressure valve unit shown in  FIG. 3 . 
       FIGS. 5A and 5B  are diagrams illustrating closed and opened states of a valve of the differential pressure valve unit according to the first embodiment of the invention, respectively, and specifically,  FIG. 5A  is a cross-sectional view showing a state where the valve of the differential pressure valve unit is closed and  FIG. 5B  is a cross-sectional view showing a state where the valve of the differential pressure valve unit is opened. 
       FIG. 6  is an enlarged cross-sectional view of a differential pressure valve unit according to a second embodiment of the invention. 
       FIG. 7  is a perspective view of a first modification of the valve lid of the differential pressure valve unit according to the first or second embodiment of the invention. 
       FIG. 8  is a perspective view of a second modification of the valve lid of the differential pressure valve unit according to the first or second embodiment of the invention. 
       FIG. 9  is a perspective view of a third modification of the valve lid of the differential pressure valve unit according to the first or second embodiment of the invention. 
       FIG. 10  is an enlarged cross-sectional view of a differential pressure valve unit according to a third embodiment of the invention. 
   

   DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Hereinafter, a differential pressure valve unit of each of embodiments of the invention will be described in detail with reference to the drawings. 
   First Embodiment 
   In this embodiment, a valve lid of a differential pressure valve unit is used as a first member. 
     FIG. 1  is an exploded perspective view of an ink cartridge including a differential pressure valve unit according to a first embodiment of the invention.  FIG. 2  is a cross-sectional view of the ink cartridge shown in  FIG. 1  taken along the line II-II.  FIG. 3  is an enlarged cross-sectional view of the differential pressure valve unit shown in  FIG. 2 .  FIG. 4  is a perspective view showing a valve lid of the differential pressure valve unit. 
   As shown in  FIG. 1 , an ink cartridge main body (liquid cartridge main body)  120  of an ink cartridge  100  includes therein an ink containing portion (liquid containing portion)  101  that is partitioned by a rib or a wall and contains ink, an ink flow passage that extends from the ink containing portion  101  to an ink supply portion (liquid supply portion)  110 , and an air connection portion that has an ink-side path, an air valve accommodating portion, and an air-side path for connecting the ink containing portion  101  to the air. The ink cartridge  100  further includes a differential pressure valve unit  130  serving as an ink supply control unit. 
   The ink supply portion  110  is disposed at a lower surface of the ink cartridge  100 . An ink supply needle of a holder, on which the ink cartridge  100  is mounted, is inserted into the ink supply portion  110 , such that ink contained in the ink containing portion  101  is supplied to a recording head of an ink jet recording apparatus. 
   The differential pressure valve unit  130  serving as an ink supply control unit supplies ink of the ink containing portion  101  to the ink supply portion  110  by a pressure difference between the ink containing portion  101  and the ink supply portion  110  generated as ink consumes. 
   The differential pressure valve unit  130  has a membrane valve  140  that can be elastically deformed and is inserted into a differential pressure valve unit accommodating portion  150 , a valve lid  160  that covers the differential pressure valve unit accommodating portion  150 , and a coil spring  133  serving as an urging member that is interposed between the membrane valve  140  and the valve lid  160 . 
   As shown in  FIG. 3 , the membrane valve  140  of the differential pressure valve unit  130  has an edge portion  141  that substantially has a cylindrical shape, a thick portion  142  that is disposed in the vicinity of the edge portion  141 , a main body portion  143  that is surrounded by the thick portion  142  and is elastically deformed, a valve lid-side protruded portion  144  that protrudes toward the valve lid  160  at the center of the main body portion  143 , that is, at a position where the coil spring  133  comes into contact with the main body portion  143 , and a main body-side protruded portion  145  that protrudes toward a through hole  152  at a wall surface  151  of the differential pressure valve unit accommodating portion  150 . 
   The membrane valve  140  is formed of an elastic material more flexible than the ink cartridge main body  120 , for example, elastomer. The valve lid-side protruded portion  144  substantially has a cylindrical shape, and the outer diameter of its section is slightly larger than the inner diameter of the coil spring  133  before the valve lid-side protruded portion  144  is attached to the coil spring  133 . Accordingly, when the valve lid-side protruded portion  144  is inserted into one end of the coil spring  133 , the coil spring  133  is accurately positioned and held with respect to the membrane valve  140 . 
   As shown in  FIG. 4 , the valve lid  160  of the differential pressure valve unit  130  has a recess portion  166  that holds the edge portion  141  of the membrane valve  140 , a spring receiving portion  167  that substantially has a cylindrical shape and holds the coil spring  133 , and a wall surface contact portion  162  that substantially has a cylindrical shape and has is disposed in the vicinity of the valve lid  160 . 
   An opposing surface  161  of the valve lid  160  to the membrane valve  140  has a shape corresponding to a movable range of the membrane valve, that is, a mortar shape. Accordingly, the interference with the valve lid  160  does not occur even though the membrane valve  140  is deformed due to a pressure applied thereto. 
   A connection port  164   a  that is connected to a connection portion  164  described below is provided at the opposing surface  161 . Since the spring receiving portion  167  is formed at a central portion of the opposing surface  161 , the connection port  164   a  is provided at a position distant from the central portion. Two groove portions  163  are provided along a diameter direction of the opposing surface  161  in order to allows a liquid to easily flow into the connection port  164   a . One of the two groove portions  163  is provided to cross the connection port  164   a.    
   The valve lid  160  substantially has a cylindrical shape, and its outer diameter is slightly larger than the inner diameter of the edge portion  141  of the membrane valve  140  before the edge portion  141  of the membrane valve  140  is attached. 
   The inner diameter of the wall surface contact portion  162  in the valve lid  160  is larger than the outer diameter of the edge portion  141  of the membrane valve  140 . Accordingly, when the edge portion  141  of the membrane valve  140  is inserted into the recess portion  166  in a state where the coil spring  133  is interposed between the valve lid  160  and the membrane valve  140 , the valve lid  160  urges the edge portion  141  in a direction spreading the edge portion  141  from the inside, and then the membrane valve  140  is held in the valve lid  160 . 
   Moreover, before the edge portion  141  of the membrane valve  140  is assembled into the valve lid  160 , only a part of the outer diameter of the valve lid  160  may be larger than the inner diameter of the edge portion  141 , and other parts may be smaller than the inner diameter of the edge portion  141 . 
   The valve lid  160  has a connection portion  164  that passes through from a side where the membrane valve  140  is attached and to a side where an outer film  121  is adhered. 
   Accordingly, when the valve lid  160  is attached to the ink cartridge main body  120 , together with the membrane valve  140 , a downstream pressure chamber  165  that is defined by the valve lid  160  and the membrane valve  140  is connected to the ink supply portion  110  through the connection portion  164 . 
   Moreover, the connection portion  164  is also connected to a downstream ink supply hole  174  that is disposed immediately on a downstream side of the through hole  152 . 
   As viewed from the differential pressure valve unit accommodating portion  150 , a circular ring-shaped protrusion  176  is provided at the wall surface  151  of the differential pressure valve unit accommodating portion  150  along an outer circumference surrounding the through holes  152  and  175 . 
   The ring-shaped protrusion  176  protrudes in a direction in which the membrane valve  140  is attached. In the section shown in  FIG. 3 , the ring-shaped protrusion  176  has a wedge shape tapered in the direction in which the membrane valve  140  is attached. 
   Since the thick portion  142  of the membrane valve  140  is more flexible than the ring-shaped portion  176 , when the differential pressure valve unit is inserted into the differential pressure valve unit accommodating portion  150  from a side close to the wall surface  151  of the differential pressure valve unit accommodating portion  150  in an order of the membrane valve  140  and the valve lid  160 , the front end of the ring-shaped protrusion  176  is pressed into contact with and wedged into the thick portion  142  of the membrane valve  140 . 
   Accordingly, an upstream pressure chamber  170  that is connected to the through hole  175  is defined by the wall surface  151 , the ring-shaped protrusion  176 , and the membrane valve  140 . 
   The ring-shaped protrusion  176  is disposed to face the valve lid  160  with the thick portion  142  of the membrane valve  140  interposed therebetween. Accordingly, the valve lid  160  is brought into contact with the thick portion  142  and presses the thick portion  142  against the ring-shaped protrusion  176 . The membrane valve  140  can reliably seal the vicinity of the upstream pressure chamber  170 . 
   An inner circumferential wall  171  that forms the differential pressure valve unit accommodating portion  150  and the outer circumference of the wall surface contact portion  162  of the valve lid  160  substantially the same shape. 
   Further, a distance between the valve lid  160  and the wall surface  151  when the wall surface contact portion  162  of the valve lid  160  is brought into contact with the wall surface  151  is slightly smaller than the sum of the height from the wall surface  151  to the front end of the ring-shaped protrusion  176  and the thickness of the thick portion of the membrane valve  140 . 
   Accordingly, an outer surface  172  of the valve lid  160  slightly protrudes from a wall surface of the ink cartridge main body  120  in the vicinity of the valve lid  160 . 
   The outer film  121  is attached to cover the outer surface  172  of the valve lid  160  and the wall surface of the ink cartridge main body  120  and to urge the outer surface of the valve lid  160 . 
   Accordingly, the outer film  121  urges the valve lid  160  toward the differential pressure valve unit accommodating portion  150 . Then, the valve lid  160  is further reliably attached to the differential pressure valve unit accommodating portion  150 , and thus sealing performance of the ring-shaped protrusion  176  and the membrane valve  140  can be increased. 
   In the vicinity of the through hole  152  of the ink cartridge main body  120 , a through hole protruded portion  152   a  is provided to protrude toward the membrane valve  140  and to come into contact with the main body-side protruded portion  145  of the membrane valve  140 . 
   Accordingly, when ink is not supplied, the main body-side protruded portion  145  of the membrane valve  140  comes into contact with the through hole protruded portion  152   a , such that the through hole  152  can be reliably blocked. 
   The upstream pressure chamber  170  is connected to an upstream ink tank  173  through the through hole  175 , and ink is supplied from the upstream ink tank  173  to the differential pressure valve unit  130 . 
   As described above, the membrane valve  140  and the coil spring  133  are held in the valve lid  160  and form the differential pressure valve unit  130 . 
     FIGS. 5A and 5B  are diagrams illustrating closed and opened states of the valve of the differential pressure valve unit  130 , respectively. Specifically,  FIG. 5A  is a cross-sectional view showing a state where the valve of the differential pressure valve unit  130  is closed, and  FIG. 5B  is a cross-sectional view showing a state where the valve of the differential pressure valve unit  130  is opened. 
   As shown in  FIG. 5A , in a state where the valve is closed, the main body-side protruded portion  145  of the membrane valve  140  comes into contact with the through hold protruded portion  152   a  of the through hole  152  by an urging force of the coil spring  133  and closes the through hole  152 . Accordingly, ink of the ink containing portion  101  is blocked so as not to flow out to the ink supply portion  110 . 
   When ink consumes from the ink supply portion  110  by the recording head of the ink jet recording apparatus on which the ink cartridge  100  is mounted, the pressure of ink in the ink supply portion  110  is lowered, and then the pressure of the downstream pressure chamber  165  is lowered through connection portions  181  and  182  schematically shown in  FIG. 2 . 
   Meanwhile, at a surface of the membrane valve  140  close to the upstream pressure chamber  170 , the pressure in the vicinity of the through hole  152  is lowered through the downstream ink supply hole  174 , but the pressure in the vicinity of the through hole  175  is not lowered. 
   Accordingly, when a force according to the pressure difference between both surfaces of the membrane valve  140  is made larger than the urging force applied to the membrane valve  140  by the coil spring  133 , as shown in  FIG. 5B , the main body-side protruded portion  145  of the membrane valve  140  is away from the through hole protruded portion  152   a , and thus the through hole  152  is opened. 
   Therefore, ink flows in an order of the upstream ink tank  173 , the through hole  175 , the upstream pressure chamber  170 , and the downstream ink supply hole  174 , and then is supplied from the ink supply portion  110  to the recording head. 
   As shown in  FIG. 5B , in a state where the valve is opened, ink is supplied to the downstream pressure chamber  165  and the ink supply portion  110  through the downstream ink supply hole  174 , and thus the pressure difference between the downstream pressure chamber  165  and the upstream ink tank  173  is released. Accordingly, the membrane valve  140  is pressed back by the urging force of the coil spring  133  and the main body-side protruded portion  145  of the membrane valve  140  closes the through hole  152 . Then, the through hole  152  is blocked from the upstream pressure chamber  170 . With the repetition of the above-described operation, ink contained in the ink containing portion  101  is supplied to the ink jet recording apparatus. 
   In this embodiment, the opposing surface  161  of the valve lid  160  to the membrane valve  140  has a shape corresponding to the movable range of the membrane valve, that is, a mortar shape. Then, as shown in  FIG. 5B , in a state where the valve is opened, even though the membrane valve  140  is deformed due to the pressure applied thereto, the interference with the valve lid  160  does not occur. For this reason, the volume in the membrane valve is reduced, without obstructing the movement of the membrane valve  140 , and thus the ink residual quantity can be reduced. Further, if the volume in the differential pressure valve is reduced, in an ink injection process, ink is easily filled into the differential pressure valve. 
   At the opposing surface  161  of the valve lid  160  to the membrane valve  140 , the groove portions  163  are provided to allow the liquid to easily flow into the connection port  164   a . Accordingly, the flow passage of ink that goes toward the connection port  164   a  can be secured by the groove portions  163 . That is, the liquid that is distant from the connection port  164   a  can be smoothly discharged through the flow passage defined by the groove portions  163 , and thus responsibility to the pressure by opening/closing of the membrane valve  140  can be improved. 
   Second Embodiment 
     FIG. 6  is an enlarged cross-sectional view of a differential pressure valve unit according to a second embodiment of the invention. 
   A differential pressure valve unit  230  according to the second embodiment is different from the differential pressure valve unit  130  according to the first embodiment in that a membrane valve  240  has an approximately U-shaped bent portion  246 , as shown in  FIG. 6 . Further, at an opposing surface  261  of the valve lid  260  to the membrane valve  240 , a recess portion  261   a  corresponding to the bent portion  246  is provided. 
   Other parts are the same as those in the first embodiment. The same parts are represented by the same reference numerals, and the descriptions thereof will be omitted. This embodiment has the same advantages as the first embodiment. 
   Next, modifications of the differential pressure valve units  130  and  230  according to the first and second embodiments of the invention will be described. 
     FIG. 7  is a perspective view of a valve lid according to a first modification.  FIG. 8  is a perspective view of a valve lid according to a second modification.  FIG. 9  is a perspective view of a valve lid according to a third modification. 
   Like the valve lid  160  shown in  FIG. 4 , in a valve lid  360  shown in  FIG. 7 , an opposing surface  361  to the membrane valve  140  has a shape corresponding to the movable range of the membrane valve, that is, a mortar shape. Further, four groove portions  363  are provided at the opposing surface  361  along the diameter direction, and one groove portion  363  and a connection port  364   a  are disposed to cross each other. 
   Like the valve lid  160  shown in  FIG. 4 , in a valve lid  460  shown in  FIG. 8 , an opposing surface  461  to the membrane valve  140  has a shape corresponding to the movable range of the membrane valve, that is, a mortar shape. Further, a plurality of groove portions  463  are provided at the opposing surface  461 , and an extension line of a center line of at least one groove portion  463  is disposed to a connection port  464   a.    
   Like the valve lid  160  shown in  FIG. 4 , in a valve lid  560  shown in  FIG. 9 , an opposing surface  561  to the membrane valve  140  has a shape corresponding to the movable range of the membrane valve, that is, a mortar shape. Further, one groove portion  563  is provided at the opposing surface  561 . Here, an extension line of a center line of the groove portion  563 , not the groove portion  563 , cross a connection port  564   a.    
   Moreover, in the valid lids  160  and  260  in the first and second embodiments and the valid lids  360 ,  460 , and  560  in the first to third modifications, the individual groove portions  163  to  563  are not necessarily in a linear shape. For example, the groove portions  163  to  563  may be in a ring shape. 
   Third Embodiment 
     FIG. 10  is an enlarged cross-sectional view of a differential pressure valve unit according to a third embodiment of the invention. 
   In this embodiment, the first member is provided in the differential pressure unit accommodating portion. 
   The same parts as those in the first embodiment are represented by the same reference numerals, and the descriptions thereof will be omitted. 
   As shown in  FIG. 10 , a differential pressure valve unit  630  has a differential pressure valve unit accommodating portion  660  having the same structure as the valve lid  160  in the first embodiment, the membrane valve  140  that is inserted into the differential pressure valve unit accommodating portion  660 , a lid member  650  having the same structure as the differential pressure valve unit accommodating portion  150  in the first embodiment, and the coil spring  133  that serves as an urging member between the membrane valve  140  and the differential pressure valve unit accommodating portion  660 . 
   Moreover, the membrane valve  140  is the same as that of the first embodiment, and the description thereof will be omitted. 
   A recess portion  666  that holds the edge portion  141  of the membrane valve  140  and a spring receiving portion  667  that holds the coil spring  133  are provided in the differential pressure valve unit accommodating portion  660 . 
   An opposing surface  661  of the differential pressure valve unit accommodating portion  660  to the membrane valve  140  has a shape corresponding to the movable range of the membrane valve, that is, a mortar shape. Accordingly, even though the membrane valve  140  is deformed due to the pressure applied thereto, the interference with the first member does not occur. 
   A connection port  664   a  is provided at the opposing surface  661  so as to be connected to a connection portion  664 . Since the spring receiving portion  667  is provided at the central portion of the opposing surface  661 , the connection port  664   a  is provided at a position distant from the central portion. Like the valve lid  160  of the first embodiment, two groove portions are provided along the diameter direction of the opposing surface  661  in order to allow the liquid to easily flow into the connection port  664   a . Further, one of the two groove portions is provided to cross the connection port  664   a.    
   Moreover, the two groove portions may be the same as the groove portions in the first and second embodiments and the modifications. 
   The connection portion  664  is also connected to a downstream ink supply hole  674  that is disposed immediately on a downstream side of a through hole  652  of the lid member  650 . 
   At an opposing surface of the lid member  650  to the membrane valve  140 , a ring-shaped protrusion  676  protruding in a direction in which the membrane valve  140  is attached and having a wedge shape that is tapered in the direction in which the membrane valve  140  is attached is provided along an outer circumference surrounding the through holes  652  and  675 . 
   Since the thick portion  142  of the membrane valve  140  is more flexible than the ring-shaped protrusion  676 , if the lid member  650  and the membrane valve  140  are inserted into the differential pressure valve unit accommodating portion  660 , the front end of the ring-shaped protrusion  676  is pressed into contact with and wedged into the thick portion  142  of the membrane valve  140 . Then, an upstream pressure chamber  670  that is connected to the through hole  675  is formed. 
   A through hole portion  652   a  that protrudes toward the membrane valve  140  and comes into contact with the main body-side protruded portion  145  of the membrane valve  140  is provided in the vicinity of the through hole  652  of the lid member  650 . 
   Accordingly, when ink is not supplied, the protruded portion  145  of the membrane valve  140  comes into contact with the through hole protruded portion  652   a , thereby reliably blocking the through hole  652 . 
   The upstream pressure chamber  670  is connected to an upstream ink tank  673  through the through hole  675 , and ink is supplied from the upstream ink tank  673  to the differential pressure valve unit  630 . 
   As described above, in this embodiment, the first member is provided in the differential pressure valve unit accommodating portion, and this embodiment has the same advantages as the first embodiment.