1. Field of the Invention
The present invention relates to a liquid filling method of a liquid container.
2. Description of the Related Art
A liquid container such as an ink tank that contains ink and supplies it to a printing head is required to be configured to be capable of smoothly supplying the contained ink (liquid) until the ink is used up without leakage thereof.
Japanese Patent Laid-Open No. 2007-062337, for example, discloses a configuration in which use of a spring and a flexible sheet generates an appropriate amount of negative pressure within a liquid containing chamber. Such a configuration as in Japanese Patent Laid-Open No. 2007-062337 enables supply of liquid at a stable flow velocity and flow rate while making it possible to contain more ink, compared to conventional configurations having an absorbent such as a sponge within the liquid containing chamber. However, there is a case where when air remains within the liquid containing chamber after the liquid containing chamber is filled with the liquid, the volume of the air fluctuates according to a change in temperature or pressure at the time of distribution, causing a concern for leakage of the liquid. Therefore, it is desirable that, at the time of shipping from a factory, the amount of the air within the liquid containing chamber be suppressed to be small to the extent that leakage does not occur even with a change in environments.
Japanese Patent Laid-Open No. 2006-175855 discloses a method in which injecting liquid into a liquid containing chamber is followed by actively collecting remaining air at a specified portion to suck the air in the volume from the liquid containing chamber. According to the method of Japanese Patent Laid-Open No. 2006-175855, shipping is available in a state in which the air within the liquid containing chamber is reduced as much as possible, whereby arrival with no leakage of the liquid can be expected even with a change in temperature or pressure at the time of distribution.
An object of the present invention is to provide a method of filling a liquid containing chamber with liquid such that an amount of remaining air is suppressed to be as small as possible.
In an aspect of the present invention, there is provided a liquid filling method of a liquid container that is equipped with: a case member having a supply port for leading out liquid; a flexible sheet which is adhesively fixed to the case member to form, together with the case member, a liquid containing chamber capable of containing the liquid; and a spring member which biases, via a plate member, the flexible sheet in a direction in which a capacity of the liquid containing chamber is enlarged, the liquid filling method comprising: a primarily pressure reducing step of reducing pressure inside the liquid containing chamber to make the capacity of the liquid containing chamber to be a minimum capacity; a primarily injecting step of injecting the liquid in an amount smaller than the minimum capacity into the liquid containing chamber with the pressure reduced in the primarily pressure reducing step; a secondarily pressure reducing step of reducing the pressure inside the liquid containing chamber with the liquid injected in the primarily injecting step to make the capacity of the liquid containing chamber to be the minimum capacity, followed by sucking air in the liquid containing chamber with a predetermined amount of air remaining; and a secondarily injecting step of injecting the liquid into the liquid containing chamber after the secondarily pressure reducing step.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
In a case where a flexible sheet is used, as in Japanese Patent Laid-Open No. 2007-062337, air is trapped in various portions depending on the shape of the flexible sheet. In that case, collection of the air to be sucked at a specified portion is difficult, causing a risk of actually sucking the liquid instead of the air even if a sucking operation of an amount corresponding to the air is performed. In other words, the configuration in which a flexible sheet is used still has had difficulty in sufficiently reducing the amount of the remaining air after the liquid is filled. The present invention is achieved to solve the above problem.
The spring member 11 biases the pressure plate 10 to enlarge the capacity of the liquid containing chamber 17, whereby a constant negative pressure is maintained within the liquid containing chamber 17. Meanwhile, the cover member 13 has an atmosphere communication port 13a formed thereon, whereby an atmospheric pressure is maintained in a space defined between the flexible sheet 12 and the cover member 13.
When the liquid containing chamber 17 is sufficiently filled with liquid (for example, ink), a negative pressure due to the biasing force of the spring member is generated within the liquid containing chamber 17. As the liquid is consumed, the negative pressure within the liquid containing chamber 17 increases and the pressure plate 10 gradually moves leftward against the biasing force of the spring member 11. However, the inner wall 16a is provided with supporting posts 14 for controlling the movement of the pressure plate 10, and the pressure plate stops moving at the point when the pressure plate 10 abuts on the supporting posts 14. The capacity in this state is the minimum capacity of the liquid containing chamber 17 at the time of consumption of the liquid.
In the present embodiment, the operation of filling the liquid container 1 with liquid is carried out in four stages as follows: a primarily pressure reducing step→a primarily injecting step→a secondarily pressure reducing step→a secondarily injecting step.
Referring back to
In the subsequent primarily injecting step, the liquid is flowed into the liquid containing chamber 17. The liquid flows into the chamber in an amount predetermined by a dispenser 3 shown in
In the subsequent secondarily pressure reducing step, the valve 4b and the valve 4c are closed and the valve 4a is opened, once again, thereby sucking the air located in the vicinity of the injection needle 5 through the injection needle 5.
In the subsequent secondarily injecting step, only the valve 4b is opened and, when the liquid is made to flow into the dispenser 3 from the liquid reservoir portion 2, the valve 4c is opened, thereby making the liquid reserved in the liquid reservoir 2 to flow into the liquid containing chamber 17. In the secondarily injecting step, an amount of the liquid obtained by subtracting, from the amount of the liquid finally required, the amount of the liquid already injected in the primarily injecting step is made to flow into the chamber by the dispenser 3. Specifically, the liquid is made to flow into the chamber in an amount corresponding to the amount obtained by subtracting, from the capacity unoccupied by the liquid within the liquid containing chamber 17, 1 to 3 cc of the air to be left. Here, the amount of the liquid obtained by subtracting indicates a target amount of the liquid for filling the liquid containing chamber.
In a series of the steps described above, the volume, 0.3 cc of the air finally remaining, is determined by the volume of the air to be left within the liquid containing chamber 17 in the secondarily pressure reducing step, the volume of the air to be left being determined by the degree of pressure reduction (−90 to −95 kPa) realized in the secondarily pressure reducing step. Further, in order to suck only the air as much as possible from the injection needle 5 so as not to significantly increase the degree of pressure reduction, it is required that the ink be injected to a certain extent in the primarily injecting step so as to sufficiently reduce the region occupied by the air. Furthermore, the amount of the liquid to be injected in the primarily injecting step depends on the pressure reducing value at the time of the secondary pressure reduction and the minimum capacity varying according to the pressure reducing value. That is, the amount of the air (0.3 cc) finally remaining is a value determined both by the degree of pressure reduction (−90 to −95 kPa) set in the secondarily pressure reducing step and by the amount of the liquid set in the primarily injecting step. In other words, relative to the minimum capacity of the liquid containing chamber 17, the minimum capacity varying according to the secondary pressure reducing value, the amount of the liquid in the primarily injecting step and the degree of the pressure reduction in the secondarily pressure reducing step are each appropriately adjusted, thereby making it possible to control the amount of the air finally remaining to a preferable value.
As stated above, according to the present embodiment, while the primary pressure reduction, the primary injection, the secondary pressure reduction, and the secondary injection are carried out in turn, the degrees of the primary pressure reduction and secondary pressure reduction are each appropriately adjusted, thereby making it possible to fill the liquid container with liquid with the air remaining in a predetermined amount.
Of the primarily pressure reducing step and the secondarily pressure reducing step, in the secondarily pressure reducing step, where there is a concern for the liquid being injected through the injection needle 5, in some cases, it is desirable that pressure reduction be carried out as slow as possible. If the pressure is rapidly reduced, air generates also in the liquid to easily raise the liquid level. Meanwhile, in view of efficient mass production at the time of manufacturing, it is desirable that an individual step be performed in a short period of time as much as possible. From this point of view, in the present embodiment, the speed of the pressure reduction is adjusted such that the sucking in the secondarily pressure reducing step is performed more slowly than in the primarily pressure reducing step. Specifically, in the secondarily pressure reducing step, gradual pressure reduction is realized by intermittently repeating opening and closing of valves.
Specifically, first, a time period of 50 to 100 ms for the valve 4a being opened (pressure reducing time) and a time period of 500 to 1000 ms for the valve 4a being closed (waiting time) are each secured, and then pressure reduction and waiting are alternately repeated about five to ten times to realize a more gradual pressure reducing effect than that in the primarily pressure reducing step.
In this case, preparing a plurality of combinations of pressure reducing time, waiting time, and the times of the repetitions to carry them out in turn is also effective. For example, at the stage where the pressure plate 10 moves, thereby changing the capacity of the liquid containing chamber 17, the pressure reducing time is set to be short (50 ms) and the waiting time is set to be long (1000 ms). Thus, as shown in
According to the liquid filling method of the present embodiment, as stated above, performing the sucking in the secondarily pressure reducing step more slowly than in the primarily pressure reducing step further suppresses the air generation during the sucking, thereby enabling the liquid container to be filled with the liquid with the air remaining in a predetermined amount.
Incidentally, in the above description, immediately after the completion of the primarily injecting step, the secondarily pressure reducing step is performed. However, it is possible to provide, between the primarily injecting step and the secondarily pressure reducing step, a step of bringing the inside of the liquid containing chamber 17 into communication with the atmosphere. Providing this step further enlarges, due to the atmospheric pressure, the capacity of the liquid containing chamber 17 expanded in the primarily injecting step. Thus, it is expected to release the air trapped between the bottom surface of the liquid containing chamber 17 and the flexible sheet 12.
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. 2014-119645, filed Jun. 10, 2014 which is hereby incorporated by reference wherein in its entirety.
Number | Date | Country | Kind |
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2014-119645 | Jun 2014 | JP | national |