Abstract:
A method for supplying a liquid to a liquid discharge head by using a liquid container, the liquid container including: a main body that is attachable to and detachable from the liquid discharge head, that has a liquid receptacle for receiving a liquid to discharge from the liquid discharge head, a supply port for supplying the liquid to the liquid receptacle, and an ejecting port for connecting the liquid receptacle to a flow path provided in the liquid discharge head; a supply-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the supply port; and an ejecting-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the ejecting port. The liquid supply method includes: opening the supply port, and hermetically sealing the ejecting port with the ejecting-port-sealing member; supplying the liquid through the supply port to the liquid receptacle; hermetically sealing the supply port with the supply-port-sealing member and then opening the ejecting port; attaching the main body to the liquid discharge head; opening the supply port; and aspirating the liquid through a nozzle hole of the liquid discharge head, and filling the nozzle hole to its top end with the liquid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application relates to and claims priority from Japanese Patent Application No. 2005-19722, filed on Jan. 27, 2005, the entire disclosure of which is incorporated herein by reference.  
       BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     The present invention relates to: a liquid container that is used by being attached to a liquid discharge head, that contains a liquid to be supplied to the liquid discharge head; the liquid discharge head to which the liquid container is attached; a liquid discharge apparatus; a method for supplying the liquid to the liquid discharge head; and a liquid discharge method.  
         [0004]     2. Related Art  
         [0005]     So-called “DNA microarrays” made by fixing DNA molecules on a substrate have been used in order to detect whether or not nucleic acid molecules having a specific base sequence exist in sample solutions. One known method for manufacturing microarrays is to discharge a solution containing DNA molecules onto the surface of a substrate, using a liquid discharge apparatus such as an ink-jet discharge apparatus.  
         [0006]     The method using the liquid discharge apparatus has the advantage of being able to manufacture high-density microarrays by narrowing the nozzle pitch. Moreover, so-called “protein chips” made by fixing proteins on the surface of a substrate have been being developed in recent years. The liquid discharge apparatus can also discharge a solution containing proteins and, therefore, is highly versatile.  
         [0007]     In general, however, in the liquid discharge apparatus, a certain amount of solution tends to remain in a liquid receptacle (so-called “reservoir”) after the discharge of liquid droplets is finished. It is difficult to collect the residual solution or clean the apparatus. The solution that cannot be collected is discarded at the time of cleaning. However, biogenic-related molecules such as DNA or proteins are often expensive or hard to procure. Therefore, it is not desirable to discard even a small amount of the residual solution. Furthermore, if the liquid discharge apparatus cannot be cleaned sufficiently and if another sample solution is used, contamination tends to occur easily and, as a result, reproducible (microarrays) data cannot be obtained in some cases.  
         [0008]     As a method for preventing the solution from remaining in the liquid receptacle and improving the usability of the solution, JP-A-2001-337096 suggests a distributive injection apparatus configured in such a way that a cartridge solution reservoir, which is removable from the distributive injection apparatus, contains a solution; and when the cartridge is attached to the distributive injection apparatus, a pin placed on the distributive injection apparatus opens a hole in the solution reservoir, thereby causing the solution to be introduced to the distributive injection apparatus through the pin.  
         [0009]     If the apparatus disclosed in JP-A-2001-337096 is used, almost the entire amount of the solution in the cartridge will flow out and be used and only some solution will remain inside the liquid discharge head. If the solution remains only inside the liquid discharge head, the residual solution amount is very small and it is easy to clean the apparatus.  
         [0010]     However, in this distributive injection apparatus, a hole is made in the cartridge when it is used. Accordingly, if the full amount of the solution in the cartridge is not used at the one time, it is difficult to preserve the remaining solution. Also, the cartridge itself has to be thrown away after use.  
       SUMMARY  
       [0011]     An advantage of some aspects of the invention is the provision of a method for supplying a liquid to a liquid discharge head, and a liquid container used for this method, where the liquid supply method and the liquid container can enable the repeated use of a sample solution in a liquid receptacle and preserve the solution without having to discard it when the sample solution remains in the liquid receptacle.  
         [0012]     In order to solve the problems described above, according to an aspect of the invention, there is provided a method for supplying a liquid to a liquid discharge head by using a liquid container, the liquid container including: a main body that is attachable to and detachable from the liquid discharge head, that has a liquid receptacle for receiving a liquid to discharge from the liquid discharge head, a supply port for supplying the liquid to the liquid receptacle, and an ejecting port for connecting the liquid receptacle to a flow path provided in the liquid discharge head; a supply-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the supply port; and an ejecting-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the ejecting port. This liquid supply method includes: opening the supply port, and hermetically sealing the ejecting port with the ejecting-port-sealing member; supplying the liquid through the supply port to the liquid receptacle; hermetically sealing the supply port with the supply-port-sealing member and then opening the ejecting port; attaching the main body to the liquid discharge head; opening the supply port; and aspirating the liquid through a nozzle hole of the liquid discharge head, and filling the nozzle hole to its top end with the liquid.  
         [0013]     This configuration enables the supply of the liquid through the supply port to the liquid receptacle in a state where the ejecting port is hermetically sealed and the supply port is opened. When the liquid is held in the liquid receptacle, if the supply port is hermetically sealed, the liquid will not flow out of the ejecting port due to the external atmospheric pressure directed toward the liquid receptacle. Therefore, the liquid in the liquid receptacle stays there even if the ejecting port is opened and turned downward. Accordingly, by hermetically sealing the supply port, opening the ejecting port, and moving the main body, the main body can be attached to the liquid discharge head so that the ejecting port is connected to the flow path leading to a discharge nozzle provided at the liquid discharge head. After the attachment of the main body to the liquid discharge head, the supply port is opened and the liquid is aspirated through the nozzle hole of the liquid discharge head, so that the liquid can be supplied to the top end of the nozzle hole. The aspiration from the nozzle hole can be conducted by closely attaching a suction unit with a gas-permeable film to the nozzle opening of the liquid discharge head.  
         [0014]     On the other hand, if the liquid remains in the liquid receptacle after the required discharge is finished, the main body can be removed from the liquid discharge head without letting the liquid flow out of the ejecting port by hermetically sealing the supply port again with the supply-port-sealing member. The removed main body is sealed with the supply-port-sealing member and the ejecting-port-sealing member and thereby can be used as a liquid preservation container without any modification.  
         [0015]     The method according to the above-described aspect of the invention can prevent waste of liquid droplets and therefore is particularly appropriate for cases where the liquid to be discharged contains biogenic-related molecules. Examples of biogenic-related molecules include, without limitation, nucleic acids, such as DNA or RNA, and proteins.  
         [0016]     It is also preferable to have the liquid receptacle contain a cleaning agent to clean the liquid discharge head. The inside of the liquid discharge head can be cleaned efficiently by supplying the cleaning agent to the liquid discharge head and discharging it from the discharge nozzle.  
         [0017]     According to another aspect of the invention, there is provided a liquid container for containing a liquid to be supplied to a liquid discharge heard. This liquid container includes: a main body including a liquid receptacle with a supply port and an ejecting port for the liquid; a supply-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the supply port; and an ejecting-port-sealing member, attachable to and detachable from the main body, capable of hermetically sealing the ejecting port; wherein the main body is attached to the liquid discharge head in such a manner that the ejecting port is connected to a flow path provided in the liquid discharge head.  
         [0018]     The liquid container having the above-described configuration can be preferably used in the aforementioned method for supplying liquid to the liquid discharge head.  
         [0019]     In the liquid container, it is preferable that the main body include an attachment member for attaching the main body to the liquid discharge head. An example of the attachment member is a convex part that engages with a concave part of the liquid discharge head. This configuration can firmly secure the liquid container on the liquid discharge head and the liquid can be discharged in a preferred manner while keeping the liquid container attached to the liquid discharge head.  
         [0020]     Moreover, it is preferable that the main body have two or more liquid receptacles, because then multiple kinds of sample solutions can be prepared at the same time and supplied to the liquid discharge head.  
         [0021]     If the main body has two or more liquid receptacles, the main body may be preferably configured in such a way that the supply ports of the respective liquid receptacles are located on the same plane of the main body, and the two or more supply ports can be hermetically sealed at the same time by firmly attaching the supply-port-sealing member to that plane. The main body may also be preferably configured in such a way that the ejecting ports of the respective liquid receptacles are located on another plane of the main body, and the two or more ejecting ports can be hermetically sealed at the same time by firmly attaching the ejecting-port-sealing member to that plane. This configuration can efficiently realize liquid supply, movement of the main body, and attachment of the main body to the liquid discharge head even when there are two or more liquid receptacles.  
         [0022]     In this case, it is desirable that a sealant be placed on the surface(s) of the supply-port-sealing member and/or the ejecting-port-sealing member that will be firmly attached to the plane(s) of the main body, where the supply ports and/or the ejecting ports are located. As a result, it is possible to enhance hermetic sealability and, more effectively utilize the method for supplying liquid to the liquid discharge head via the atmospheric pressure—using an aspect of the invention.  
         [0023]     It is also preferable that the internal surfaces of the ejecting ports be treated to become lyophilic, while the plane where the ejecting ports are located be made lyophobic. As a result, when the main body is attached to the liquid discharge head, liquid leakage can be prevented at the connection between the ejecting ports and the flow path of the liquid discharge head. Also, when the supply ports of the main body are hermetically sealed with the supply-port-sealing member and the main body is then removed from the liquid discharge head, meniscuses can be formed stably in the ejecting ports and liquid leakage can be prevented when moving the main body.  
         [0024]     According to further aspects of the invention, a liquid discharge head to which the liquid container according to the aforementioned aspect of the invention is attached, as well as a liquid discharge apparatus including this liquid discharge head are provided. The liquid discharge head and the liquid discharge apparatus are configured so that the liquid container according to the aforementioned aspect of the invention can be freely attached to and detached from them. Moreover, the liquid discharge head and the liquid discharge apparatus can preferably employ the method for supplying liquid to the liquid discharge head according to the aforementioned aspect of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1  is a perspective view of a liquid container according to an aspect of the invention.  
         [0026]      FIG. 2  illustrates the steps of a method for supplying a liquid to a liquid discharge head according to an aspect of the invention.  
         [0027]      FIG. 3  is an example plan view of a liquid delivery plate.  
         [0028]      FIG. 4  is an example plan view of another liquid delivery plate.  
         [0029]      FIG. 5  illustrates a liquid preservation method using the liquid container according to an aspect of the invention. 
     
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0030]     An embodiment of the invention will be described with reference to the attached drawings.  
         [0031]     Liquid Container  
         [0032]      FIG. 1  is a perspective view of a liquid container  100  used in a method for supplying liquid to a liquid discharge head according to an aspect of the invention. The liquid container  100  includes a main body  10 , a supply-port-sealing member  20 , and an ejecting-port-sealing member  30 . In this embodiment, the liquid container  100  is mainly used to supply a solution containing biogenic molecules, such as DNA or proteins, to the liquid discharge head.  
         [0033]     The main body  10  has: wells  16  that are liquid receptacles; supply ports  12  for supplying a liquid to the wells  16 ; and ejecting ports  14  for connecting the wells  16  to flow paths provided in the liquid discharge head. The main body  10  can be stably attached to the liquid discharge head by engaging convex parts  18   b  (attachment members) on the two opposite side faces of the main body  10 , with concave parts of the liquid discharge head described later. In this embodiment, the main body  10  has 128 holes (16×8) for wells  16 , but can be configured according to the intended use, for example, as a general-purpose microtiter plate with 96 holes or 384 holes. Referring to  FIG. 1 , all the supply ports  12  of the wells  16  are located on the top face of the main body  10 , while all the ejecting ports  14  of the wells  16  are located on the bottom face of the main body  10 .  
         [0034]     As shown in  FIG. 1 , the supply-port-sealing member  20  is to be attached to the top of the main body  10  and can hermetically seal all the supply ports  12  of the wells  16  at the same time. A sealant  22  is placed on the part of the supply-port-sealing member  20  that comes into contact with the top face of the main body  10 , in order to enhance hermetical sealability. By engaging convex parts  18   a  on the two opposite side faces of the main body  10  with concave parts  24  on the supply-port-sealing member  20 , the sealant  22  is firmly attached to the supply ports  12 , thereby hermetically sealing the supply ports  12 .  
         [0035]     Moreover, as shown in  FIG. 1 , the ejecting-port-sealing member  30  is to be attached to the bottom of the main body  10  and can hermetically seal all the ejecting ports  14  of the wells  16  at the same time. A sealant  32  is placed on the part of the ejecting-port-sealing member  30  that comes into contact with the bottom face of the main body  10 . By engaging the convex parts  18   b , that are also used as the attachment members for attachment to the liquid discharge head, with concave parts  34  of the ejecting-port-sealing member  30 , the sealant  32  is firmly attached to the ejecting ports  14 , thereby hermetically sealing the ejecting ports  14 .  
         [0036]     There is no particular limitation on the materials for the supply-port-sealing member  20  and the ejecting-port-sealing member  30 . However, if they are made from flexible materials, it will be easier to make the convex parts  18   a  and  18   b  engage with the concave parts  24  and  34 . Preferred examples of the materials are flexible resins such as polystyrene or polypropylene, which are inexpensive and high productivity. Commercially available packing materials can be used as the sealants  22  and  32 .  
         [0037]     In this embodiment, the internal surfaces of the ejecting ports  14  are treated to become hydrophilic (or lyophilic) and the surface where the ejecting ports  14  are located, that is, the bottom face of the main body  10  is treated to become hydrophobic (or lyophobic). An example of a method for making the internal surfaces hydrophilic is to coat the internal surfaces with hydrophilic polymers that have high affinity for biogenic molecules. Examples of such polymers include hydroxyethyl methacrylate, N-vinyl pyrrolidone, dimethylacrylamide, glycerol methacrylate, and polyethylene glycol methacrylate. An example of a method for making the bottom face lyophobic (or hydrophobic) is to form a hydrophobic film by evaporating a hydrophobic material, such as fluoroalkyl silane or polyfluoroethylene, by vacuum evaporation. When the liquid is introduced from the ejecting ports  14 , the above-described configuration can prevent the liquid from leaking out and running all over the connection parts between the ejecting ports  14  and the flow paths provided in the liquid discharge head.  
         [0038]     Method for Supplying Liquid to Liquid Discharge Head  
         [0039]      FIG. 2  illustrates a method for supplying a liquid to a liquid discharge head, using the liquid container  100 . As shown in  FIG. 2A , the ejecting-port-sealing member  30  is attached to the bottom face of the main body  10  to hermetically seal the ejecting ports  14  by engaging the convex parts  18   b  of the main body  10  with the concave parts  34  of the ejecting-port-sealing member  30 .  
         [0040]     Next, as shown in  FIG. 2B , a liquid  40  is supplied through the supply ports  12  into the wells  16 . The liquid  40  can be, for example, a solution containing biogenic-related molecules such as nucleic acids or proteins and be supplied by using a pipet, an automatic distributive injector, or the like. Subsequently, as shown in  FIG. 2C , by engaging the convex parts  18   a  of the main body  10  with the concave parts  24  of the supply-port-sealing member  20 , the supply-port-sealing member  20  is attached to the top face of the main body  10 , thereby hermetically sealing the supply ports  12 . Now, as shown in  FIG. 2D , the ejecting-port-sealing member  30  is removed from the main body  10 . At this moment, since the supply ports  12  are hermetically sealed with the supply-port-sealing member  20 , the liquid  40  is not affected by the external atmospheric pressure through the supply ports  12 , and is affected only by the external atmospheric pressure directed through the ejecting ports  14  toward the inside of the wells  16 . As a result, even if the ejecting ports  14  face downward, the liquid  40  does not flow out of the ejecting ports  14 .  
         [0041]     Next, the main body  10  kept in the above-described state is moved to above a liquid discharge head  200 , and is then attached to the liquid discharge head  200  as shown in  FIG. 2E . The liquid discharge head  200  is part of a liquid discharge apparatus according to an aspect of the invention and is configured in such a way that the main body  10  can be easily attached to and detached from the liquid discharge head  200 .  
         [0042]     The configuration of the liquid discharge head  200  will be described below. The liquid discharge head  200  is made of a silicon substrate or a glass substrate and includes a nozzle hole  214  for discharging the liquid, and a discharge head chip  300  having a compression chamber  212  or similar. Two liquid delivery plates  202  and  206  are layered above the discharge head chip  300 . By layering the two liquid delivery plates  202  and  206 , liquid flow paths that connect the ejecting ports  14  of the main body  10  of the mounted liquid container  100  to the nozzle hole  214  are formed. These liquid delivery plates  202  and  206  are fixed to stoppers  210 . The main body  10  is attached to the liquid discharge head  200  by engaging concave parts  211  of the stoppers  210  with the convex parts  18   b  (attachment members) of the main body  10 .  
         [0043]     It is also preferable that a sealant  204  with through-holes located at positions corresponding to those of the ejecting ports  14  be placed on the liquid delivery plate  202 . By placing this sealant  204  so, it is possible to enhance the hermetical sealability and prevent liquid leakage between the liquid delivery plate  202  and the main body  10 .  
         [0044]      FIG. 3  is a plan view of the liquid delivery plate  202 . The liquid delivery plate  202  has the same number of through-holes  203  as the ejecting ports  14 ; the through-holes  203  are located at positions corresponding to the ejecting ports  14 ; and the diameter of each through-hole  203  is equal to that of each ejecting port  14 . The liquid  40  flowing out of the ejecting ports  14  passes through the through-holes  203  and flows into the flow paths provided in the liquid delivery plate  206 .  
         [0045]      FIG. 4  is a plan view of the liquid delivery plate  206  in which grooves  208 , flow paths, are made. The grooves  208  are formed on the surface of the liquid delivery plate  206  and start from the positions corresponding to the through-holes in the liquid delivery plate  202 . In this embodiment, the grooves  208  start from 128 start points. The end points of the respective grooves  208  are located above the discharge head chip  300 . Holes  207  that pass through the liquid delivery plate  206  are made at the end points, so that the grooves  208  are connected to the compression chamber  212 .  
         [0046]     As shown in  FIG. 2E , while the supply ports  12  are hermetically sealed with the supply-port-sealing member  20 , the liquid  40  does not flow out of the ejecting ports  14  and is held in the wells  16 .  
         [0047]     Subsequently, as shown in  FIG. 2F , the supply-port-sealing member  20  is removed from the main body  10  to open the supply ports  12 . A suction cap  400  is firmly attached to the bottom face of the discharge head chip  300  where the nozzle hole  214  is open, and aspiration is conducted in the direction indicated with an arrow in  FIG. 2F . The aspiration causes the liquid  40  to pass through the through-holes  203  in the liquid delivery plate  202 , the grooves  208  in the liquid delivery plate  206 , and then the through-holes  207  in the liquid delivery plate  206 , be introduced into the compression chamber  212 , and then reach the nozzle hole  214 . A PTFE membrane  410  with micropores (average pore size: 3 μm) is mounted on the surface of the suction cap  400  and is pressed against the nozzle surface with the restorative force of a sponge  420  in the cap  400 . Gas can permeate through this membrane  410 , but liquid cannot. Therefore, the liquid  40  which has reached the nozzle hole  214  will not be ejected into the suction cap  400 . After the suction cap  400  is moved away from the nozzle surface and the compression chamber  212  is pressurized, the liquid  40  is discharged from the nozzle hole  214 . Almost the entire amount of the liquid  40  in the wells  16  can be ejected from the ejecting ports  40  by repeating the above-described discharge process. If the main body  10  is removed and some liquid  40  remains in the wells  16 , it will be only in very small amounts, in the through-holes  203  in the liquid delivery plate  202  and the grooves  208  and through-holes  207  in the liquid delivery plate  206 , because these holes and grooves are very narrow.  
         [0048]     Cleaning  
         [0049]     After the liquid  40  in the wells  16  is gone, the main body  10  can be removed from the liquid discharge head  200  and cleaned sufficiently.  
         [0050]     On the other hand, the inside of the flow paths in the liquid delivery plates  202  and  206  and the discharge head chip  300  can be cleaned appropriately by the method according to an aspect of the invention described above for supplying liquid to the liquid discharge head, using a cleaning agent as the liquid  40 . If a rinse process is necessary after cleaning with the cleaning agent, any preferred solution for the rinse process may be used as the liquid  40  by employing the method for supplying liquid to the liquid discharge head according to the aforementioned aspect of the invention.  
         [0051]     Sample Preservation  
         [0052]     If the liquid  40  containing a sample remains in the wells  16  after it is supplied to the liquid discharge head and discharged as necessary by using the liquid container  100  according to the aforementioned aspect of the invention, the liquid  40  can be preserved as it is by using the liquid container  100 .  
         [0053]      FIG. 5  shows a preservation method. If the liquid  40  remains in the wells  16  as shown in  FIG. 5A , firstly the supply-port-sealing member  20  is firmly attached to the main body  10  to hermetically seal the supply ports  12  as shown in  FIG. 5B . Then, the main body  10  kept in the above-described state is removed from the liquid discharge head  200  as shown in  FIG. 5C , so that the liquid  40  will not flow out of the ejecting ports  14 . Subsequently, as shown in  FIG. 5D , the ejecting-port-sealing member  30  is attached to the main body  10 . As a result, the wells  16  are completely hermetically sealed and the liquid  40  can be preserved by conducting any necessary temperature control or the like depending on the type of the sample.  
         [0054]     When it becomes necessary to discharge the liquid  40  later by using the liquid discharge apparatus, the liquid  40  can be supplied to the liquid discharge head by following the steps shown in  FIGS. 2C  to  2 F.  
         [0055]     However, the invention is not limited to the embodiment described above, and can be modified or changed in various ways within the scope of the subject matter of the invention. For example, regarding the liquid container described above, the above embodiment describes an example where the convex parts are provided only on the two opposite side faces of the main body. However, the convex parts may be provided on all the four side faces of the main body. Moreover, it is possible to select, for example, the size and materials of the liquid container  100 , or the number of the wells  16  according to the intended use as necessary. Also, the liquid  40  is not limited to a solution containing biogenic molecules such as DNA, proteins, or cells, or to a cleaning agent. Any liquid may be used as long as it can be discharged using the liquid discharge apparatus.