1. Field of the Invention
This invention relates to a method of controlling an ink jet recording apparatus that supplies ink from main tanks storing ink to ink jet heads through sub-tanks.
2. Prior Art
Conventionally, in a relatively large-sized ink jet recording apparatus, such as an ink jet printer, a main tank for storing ink and an ink jet head are connected to each other through an ink tube such that ink is supplied from the main tank to the ink jet head by suction action caused by operation of the ink jet head.
The ink jet recording apparatus of this kind suffers from a problem that it is difficult to maintain stable ejecting performance of the ink jet head due to changes in water head pressure since the ink level in the ink tank depends on the amount of ink stored in the ink tank. Further, to prevent ink from dripping from the ink jet head, it is necessary to arrange the ink jet head at a location slightly higher than the ink tank. However, it is not always possible to properly arrange a large-sized ink tank within a limited space in the ink jet recording apparatus.
To overcome the above problems, so as to increase the degree of freedom of arrangement of the ink tank, it is contemplated that a sub tank is interposed between the ink tank (main tank) and the ink jet head to secure the above water head pressure by using the sub tank. Further, it is preferred that the sub-tank is a bag-like one formed by a vapor deposited film or the like so as to prevent air from being mixed in the ink.
However, in the case of the ink jet recording apparatus which uses the sub-tank as described above, it is preferable to employ a pressure tank since pressure variation is undesirable for ink supply from the main tank to the sub-tank. In the case of the use of the pressure tank, when it is necessary to make the pressure tank open to the atmosphere e.g. because of abnormal stoppage of the apparatus or for replacement of the main tank, safety must be ensured. Further, since ink ejected from the ink jet head is supplied from the sub-tank, it is necessary to realize stable supply of ink from the main tank to the sub-tank.
It is an object of the invention to provide a method of controlling an ink jet recording apparatus, which ensures safety in replacing main tanks or the like and at the same time enables stable supply of ink from main tanks to sub-tanks.
To attain the above object, according to a first aspect of the invention, there is provided a method of controlling an ink jet recording apparatus including a main tank having an information storage section for storing an ink amount and ink attributes as ink information and replaceably received in a pressure tank, a sub-tank communicating with an ink jet head and storing ink sent from the main tank by pressure in the pressure tank, a tank-accommodating block for accommodating the main tank together with the pressure tank, and a control section capable of storing the ink information to be stored in the main tank. The ink jet recording apparatus supplies the ink in the main tank to the sub-tank by opening and closing a valve arranged on a upstream side of the sub-tank in response to a signal indicative of an ink fill-up/shortage condition of the sub-tank. The method comprise the step of stopping operation of a pressure source for pressurizing the pressure tank and at the same time making an inside of the pressure tank open to the atmosphere as well as writing an item of the ink information concerning the ink amount of the main tank stored in the control section into the information storage section of the main tank, in response to a signal indicative of opening of a door of the tank-accommodating block during operation of the apparatus.
According to this method, when the door of the tank-accommodating block is opened in response to the signal indicative of opening of the door, the operation of the pressure source for pressurizing the pressure tank is stopped, and the inside of the pressure tank is made open to the atmosphere. This enables makes it possible to instantly reduce pressure in the pressure tank. More specifically, if an operator (user) erroneously opens the door without carrying out operation of making the pressure tank open to the atmosphere, the pressure in the pressure tank can be reduced before it is made open to the atmosphere. This makes it possible to reliably prevent the user from erroneously opening the pressure tank under high pressure. Further, when the door is opened, ink information concerning the ink amount of the main tank stored in the control section is written in the information storage section of the main tank, so that it is possible to prevent any missing of the ink information from occurring, and at the same time confirm the identity of the main tank when the door is closed again.
Preferably, the method further comprises the step of closing the valve arranged on the upstream side of the sub-tank in response to the signal indicative of opening of the door of the tank-accommodating block during operation of the apparatus.
According to this preferred embodiment, even if ink is being supplied through an ink supply passage when the door of the tank-accommodating block is opened, the ink supply passage is blocked by closing the valve. Therefore, it is possible to positively stop the ink supply. Further, since the ink supply is carried out after the ink information is stored in the information storage section of the main tank, it is possible to prevent generation of an error between the information stored in the information storage section of the main tank and the information stored in the control section.
Preferably, the method further comprises the step of stopping cleaning operation of sucking ink from the ink jet head in response to the signal indicative of opening of the door of the tank-accommodating block during operation of the apparatus.
According to this preferred embodiment, even if the cleaning operation is being carried out by sucking ink from the ink jet head, when the door of the tank-accommodating block is opened, and an ink supply passage from the sub-tank to the ink jet head is not placed in a negative pressure state by the cleaning operation, which contributes to prevention of reverse flow of ink caused by the ink supply passage being in the negative pressure state upon termination of the cleaning operation. This makes it possible to prevent the ink jet head from being contaminated by ink which has once flown out of the ink jet head by suction. Further, although there is a case in which ink is replenished during cleaning operation, it is possible to prevent an error from being produced between the ink information stored in the information storage section of the main tank when the door is opened and the ink information stored in the control section, by inhibiting the cleaning operation when the door is opened.
Further, when the ink jet head includes a plurality of nozzle arrays for different ink colors, it is possible to prevent reverse flow of ink caused by cleaning operation continued with the door of the tank-accommodating block open, thereby effectively preventing the inside of the ink jet head from being contaminated by a mixture of different colors of inks.
Preferably, the method further comprises the steps of starting operation of the pressure source for pressurizing the pressure tank in response to a signal indicative of closing of the door of the tank-accommodating block during operation of the apparatus, when an item of the ink information concerning the ink attributes stored in the information storage section of the main tank and an item of the ink information concerning the ink attributes read out from the control section agree with each other, and at the same time when ink end information indicative of an ink-used-up condition is not contained in the item of the ink information concerning the ink amount stored in the information storage section of the main tank, and executing error notification in response to the signal indicative of closing the door of the tank-accommodating block during operation of the apparatus, when the item of the ink information concerning the ink attributes stored in the information storage section of the main tank and the item of the ink information concerning the ink attributes read out from the control section are different from each other, or when the ink end information is contained in the item of the ink information concerning the ink amount stored in the information storage section of the main tank.
According to this preferred embodiment, if the ink information concerning the ink attributes stored in the information storage section of the main tank, and that read out from the control section agree with each other, even if the ink information concerning the ink amount stored in the information storage section of the main tank, and that read out from the control section do not agree with each other, ink supply is permitted, and hence the operation of the pressure source for pressurizing the pressure tank is started. However, if the ink information concerning the ink amount stored in the storage section of the main tank contains ink end information indicative of an ink-used-up condition of the main tank, it is judged that the main tank is empty (e.g. a case of a main tank being replaced by an empty main tank), and hence ink supply cannot be executed, and accordingly the operation of the pressure source is not started.
On the other hand, if the ink information concerning the ink attributes stored in the information storage section of the main tank, and that read out from the control section do not agree with each other, that is, for instance, if the two items of ink information are different from each other in ink color or ink quality (e.g. between pigment ink and dye ink), it is likely to cause some trouble in carrying out printing operation, and therefore, the error notification is executed. Similarly, if the ink end information is contained in the ink information stored in the main tank, error notification is executed since it is necessary to replace the main tank. This makes it possible to effectively prevent the main tank from being erroneously and improperly replaced.
Preferably, the ink end information is a predetermined value of the ink amount exceeding a capacity of the main tank.
According to this preferred embodiment, it is possible to reduce a memory area in the information storage section of the main tank as well as to facilitate control operations (determination of an ink end) in the control section.
Preferably, the ink jet head, the sub-tank, and the main tank comprise a plurality of ink jet heads, a plurality of sub-tanks, and a plurality of main tanks, provided for different ink colors, and the method further comprises the steps of starting ink supply on a sub-tank-by-sub-tank basis in response to a signal indicative of detection of shortage of ink in the sub-tank, and stopping the ink supply in response to a signal indicative of detection of a fill-up of ink in the sub-tank on a sub-tank-by-sub-tank basis.
According to this preferred embodiment, ink supply from the main tank is controlled in response to the signal indicative of detection of shortage of ink in a sub-tank and the signal indicative of detection of a fill-up of ink in the sub-tank. This makes it possible to realize stable supply of ink from the ink tank to the sub-tank in dependence on the amount of ink stored in the sub-tank. Further, since ink is supplied based on the signal indicative of detection of shortage of ink in the sub-tank and the signal indicative of detection of a fill-up of ink in the sub-tank detected on a sub-tank-by-sub-tank basis, the amount of ink supply by one operation can be made uniform on a sub-tank-by-sub-tank basis.
Preferably, the ink jet head, the sub-tank, and the main tank comprise a plurality of ink jet heads, a plurality of sub-tanks, and a plurality of main tanks, provided for different ink colors, and the method further comprises the steps of starting ink supply to the sub-tanks in response to a signal indicative of detection of shortage of ink of at least one of the plurality of sub-tanks, and stopping the ink supply in response to a signal indicative of detection of a fill-up of ink, on a sub-tank-by-sub-tank basis.
According to this preferred embodiment, since ink is supplied in response to the signal indicative of shortage of ink in the sub-tank, it is possible to stably supply ink to the sub-tank in dependence on the amount of ink stored in the sub-tank. Further, if the signal indicative of shortage of ink is detected from any one of the plurality of sub-tanks, ink starts to be supplied to all the sub-tanks, so that the number of times and timing of supply of ink from the main tank can be made uniform between all the sub-tanks.
Preferably, the ink jet head, the sub-tank, and the main tank comprise a plurality of ink jet heads, a plurality of sub-tanks, and a plurality of main tanks, provided for different ink colors, and the method further comprises the steps of starting ink supply to all sub-tanks when at least one of signals each indicative of detection of a fill-up of a corresponding one of the plurality of sub-tanks is turned off, and stopping the ink supply in response to a signal indicative of detection of a fill-up of ink, on a sub-tank-by-sub-tank basis.
According to this preferred embodiment, if there is at least one of the plurality of sub-tanks of which a fill-up is not detected, ink starts to be supplied to all the sub-tanks, so that it is possible to perform stable ink supply such that all the sub-tanks are filled with ink as well as to make the number of times and timing of supply of ink from the main tank uniform between all the sub-tanks.
Preferably, the method further comprises the step of executing error notification when an actual replenishing time period from a start of the ink supply to each sub-tank to detection of a fill-up of ink therein exceeds an predetermined time period.
According to this preferred embodiment, by executing error notification when the actual replenishing time period exceeds a predetermined time period, the user can be notified that ink is not properly supplied due to an ink end (ink-used-up condition) of the main tank or a failure of the apparatus. Further, it is possible to prevent time from wastefully passing, when there has occurred leakage of ink, or the like.
Preferably, the step of executing error notification comprise the steps of stopping operation of the pressure source for pressurizing the pressure tank and making an inside of the pressure tank open to the atmosphere, and writing the item of the ink information concerning the ink amount of the main tank stored in the control section, into the information storage section of the main tank.
According to this preferred embodiment, when ink is not properly supplied due to a failure of the apparatus or the like, operation of the pressure source is stopped, the inside of the pressure tank is made open to the atmosphere to make pressure in the inside of the pressure tank equal to the atmospheric pressure, and ink supply from the main tank is stopped. This makes it possible to prevent improper ink supply from being continued. Further, ink information concerning the ink amount stored in the control section is stored in the information storage section of the main tank when operation of the pressure source is stopped, so that the information of the amount of ink stored in the main tank (amount of ink consumption) can be grasped accurately without causing any deficit in the ink information concerning the ink amount stored in the information storage section of the main tank.
To attain the above object, according to a second aspect of the invention, there is provided a method of controlling an ink jet recording apparatus including a main tank having an information storage section for storing ink information and replaceably received in a pressure tank, a sub-tank communicating with an ink jet head and storing the ink sent from the main tank by pressure in the pressure tank, a tank-accommodating block for accommodating the main tank together with the pressure tank, and a control section capable of storing ink information. In response to a signal indicative of an ink fill-up/shortage condition of the sub-tank, the ink jet recording apparatus supplies the ink in the main tank to the sub-tank by opening and closing a valve arranged on a upstream side of the sub-tank, and stores an amount of ink consumed by operation of the ink jet head, a number of times of ink replenishment to the sub-tank, an ink capacity of the main tank, in the control section, as the ink information. The method comprise the step of adding an amount of ink consumed through the sub-tank to an amount of ink consumed through the main tank when ink starts to be supplied to the sub-tank, and storing the resulting amount in the control section, and resetting the amount of ink consumed through the sub-tank.
According to this method, since the amount of ink consumed through the main tank is calculated as a cumulative total of amounts of ink consumed through the sub-tank, it is possible to consolidate calculations of the amounts of consumed ink. This makes it possible to simplify the construction of the control system without any need to provide a dedicated counter for the main tank. Further, even when ink is not properly replenished from the main tank to the sub-tank due to some failure (e.g. leakage of ink), the amount of ink consumed through the main tank and the amount of ink consumed through the sub-tank do not become different from each other. Further, the amount of ink consumed through the sub-tank (amount of remaining ink therein) can be always grasped separately from the amount of ink consumed through the main tank.
Preferably, the method further comprises the steps of counting the number of times of ink replenishment to the sub-tank for storage in the control section when ink starts to be supplied to the sub-tank, and resetting the number of times of ink replenishment to the sub-tank stored in the control section when the sub-tank is replaced.
According to this preferred embodiment, it is possible to grasp the number of times of ink replenishment to the sub-tank which undergoes wear and tear (material fatigue and degradation) by repeated ink replenishment from the main tank. This makes it possible to estimate the remaining service life of the sub-tank based on the number of times of ink replenishment, and carry out maintenance of the sub-tank based on proper timing of replacement.
Preferably, the method further comprises the step of writing the amount of ink consumed through the main tank into the information storage section of the main tank when there has occurred abnormal stoppage of the system, when a door of the tank-accommodating block is opened during operation of the apparatus, when an initial ink-filling process for filling ink in the sub-tank is carried out, or when the ink in the main tank is used up.
According to this preferred embodiment, the amount of ink consumed through the main tank is written when work or operation concerning the main tank is expected to be carried out, e.g. when there has occurred abnormal stoppage of the apparatus, or when a door of the tank-accommodating block is opened during operation of the apparatus. Therefore, even if such operation is carried out, no deficit is caused in information concerning the amount of consumed ink which is stored in the information storage section of the main tank.
Preferably, the method further comprises the step of writing a specific ink amount value exceeding a capacity of the main tank into the information storage section of the main tank, when the ink in the main tank is used up.
According to this preferred embodiment, once a main tank comes to an ink end (used-up) condition, it can be determined as such based on the specific ink amount value written into the information storage section thereof. Therefore, even if an empty main tank is set for use by mistake, error notification is carried out immediately, so that it is possible to cope with such a state without delay.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.