hereinafter , a differential pressure valve unit of each of embodiments of the invention will be described in detail with reference to the drawings . in this embodiment , a valve lid of a differential pressure valve unit is used as a first member . fig1 is an exploded perspective view of an ink cartridge including a differential pressure valve unit according to a first embodiment of the invention . fig2 is a cross - sectional view of the ink cartridge shown in fig1 taken along the line ii - ii . fig3 is an enlarged cross - sectional view of the differential pressure valve unit shown in fig2 . fig4 is a perspective view showing a valve lid of the differential pressure valve unit . as shown in fig1 , 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 fig3 , 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 fig4 , 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 fig3 , 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 . fig5 a and 5b are diagrams illustrating closed and opened states of the valve of the differential pressure valve unit 130 , respectively . specifically , fig5 a is a cross - sectional view showing a state where the valve of the differential pressure valve unit 130 is closed , and fig5 b is a cross - sectional view showing a state where the valve of the differential pressure valve unit 130 is opened . as shown in fig5 a , 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 fig2 . 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 fig5 b , 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 fig5 b , 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 fig5 b , 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 . fig6 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 fig6 . 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 . fig7 is a perspective view of a valve lid according to a first modification . fig8 is a perspective view of a valve lid according to a second modification . fig9 is a perspective view of a valve lid according to a third modification . like the valve lid 160 shown in fig4 , in a valve lid 360 shown in fig7 , 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 fig4 , in a valve lid 460 shown in fig8 , 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 fig4 , in a valve lid 560 shown in fig9 , 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 . fig1 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 fig1 , 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 .