Patent Application
20110310159
1. Field of the Invention
The present invention relates to an inkjet apparatus using an inkjet head ejecting multiple types of inks different in viscosity after evaporation of solvent, and a method for judging replacement timings for components of the apparatus.
2. Description of the Related Art
When ejecting a liquid from a print head, an inkjet apparatus also generates droplets (hereinafter, also called a mist) each smaller than a main droplet. A mist does not adhere only to an ejection surface. While floating in an air current within a printing apparatus, the mist may adhere also to components constituting the printing apparatus such as a mechanism for moving a print medium and an inkjet head relative to each other, a mechanism for performing a recovery operation, and a sensor for performing detection required to perform a printing operation. In other words, the adhesion of ink adversely affects not only the inkjet head but also the components constituting the printing apparatus. As the viscosity increases due to evaporation of ink solvent, the performance of each component, particularly movable component is reduced, and eventually the performance of the printing apparatus main body cannot be maintained. For this reason, it is necessary to know how much the viscosity of mist adhering to each of these components in the apparatus main body is increased and to make a maintenance such as replacement of the component when it is estimated that the component performance is reduced to such an extent that the performance of the printing apparatus main body cannot be maintained.
To counter such problem, Japanese Patent Laid-Open No. 2005-246697 discloses a configuration which is provided with an ink collecting unit for collecting mist and a fan for generating an air current to suction the mist and lead it toward the collecting unit. Moreover, Japanese Patent Laid-Open No. 2005-246697 discloses a technique in which the amount of ink accumulated in the ink collecting unit as a result of the mist suction is calculated by estimating the amount of mist generated, and, when the amount reaches the maximum ink amount collectable by the ink collecting unit, replacement of the ink collecting unit is prompted.
In an inkjet apparatus, an air current occurs due to ejection of main droplets, and, particularly in a so-called serial printing apparatus, an air current occurs also by the movement of an inkjet head. It should be considered that these air currents also affect the floating state of mist. In other words, not all of the generated mist is necessarily led to the collecting unit by simply generating an air current to suction the mist and lead it toward the collecting unit as in Japanese Patent Laid-Open No. 2005-246697. Accordingly, adhesion of mist on the components constituting the printing apparatus cannot be effectively prevented by this configuration.
Accordingly, it is still necessary to know how much the viscosity of mist adhering to each of the components in the apparatus main body is increased and to make a maintenance such as replacement of the components when it is estimated that the component performance is reduced to such an extent that the performance of the printing apparatus main body cannot be maintained. The technique disclosed in Japanese Patent Laid-Open No. 2005-246697, however, is only for replacement of the collecting unit, and does not consider adhesion of mist on other components in the main body. Moreover, even if the generated mist is effectively led to the collecting unit by the technique disclosed in Japanese Patent Laid-Open No. 2005-246697, the mist may adhere to the suction fan itself in some cases. However, this problem is not recognized in Japanese Patent Laid-Open No. 2005-246697.
As described above, in a situation where an ink of strong tendency to adhere fixedly, particularly an ink which increases in viscosity along with the evaporation of ink solvent is being used more and more, it is highly desirable to know how much the viscosity of mist adhering to each of the components in the main body is increased and to appropriately know the replacement timing. Moreover, the degree of increase in viscosity along with the evaporation of ink solvent is different depending on the type of ink used in the printing apparatus. Thus, it is highly desirable to appropriately know how much the fixed adhesion is developed and the replacement timing while considering such difference as well.
In view of the above-described problems, an object of the present invention is to enable each of components in an inkjet apparatus main body to be replaced at an appropriate timing in consideration of types of inks used in a printing apparatus, the components including moveable components such as a mechanism for moving a print medium and an inkjet head relative to each other.
In an aspect of the present invention, there is provided an inkjet apparatus using an inkjet head ejecting a plurality of types of inks different in viscosity after evaporation of solvent, the inkjet apparatus comprising:
an acquisition unit configured to acquire information about a consumption amount of each of the plurality of types of inks; and
a judgment unit configured to judge a replacement timing for a component constituting the inkjet apparatus by using the information acquired by the acquisition unit and a generation rate in amount of ink droplets different from main ink droplets ejected from the inkjet head.
In another aspect of the present invention, there is provided a judging method for judging a replacement timing for a component constituting an inkjet apparatus using an inkjet head ejecting a plurality of types of inks different in viscosity after evaporation of solvent, the method comprising the steps of:
acquiring information about a consumption amount of each of the plurality of types of inks; and
judging a replacement timing for the component by using the information acquired in the acquisition step and a generation rate in amount of ink droplets different from main ink droplets ejected from the inkjet head.
According to the present invention, a replacement timing for a component is judged by using the consumption amounts of the respective multiple types of inks different in viscosity after evaporation of solvent and the generation rate in amount of ink droplets. Accordingly, the component is replaced at an earlier timing when a large amount of ink which is strongly susceptible to fixed adhesion and increase in viscosity is used, which prevents fixed adhesion from influencing the print performance and the printing apparatus main body. By contrast, when a large amount of ink which is less susceptible to fixed adhesion and increase in viscosity is used, the component is replaced at a later timing and thus can be used until reaching its lifetime.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, some embodiments of an inkjet apparatus of the present invention and a method for judging a replacement timing for a component constituting the apparatus will be described in detail with reference to the drawings. The present invention is widely applicable to inkjet apparatuses using media such as paper, cloth, leather, nonwoven fabric, plastic sheet, metal, and substrate. Specific application examples include printing machines such as printers, copiers, and facsimiles using an inkjet method, industrial production equipment, sprayers, and so on.
In addition, in
The inkjet head 3 is provided with: the multiple ejection openings 3a formed on the ejection face 3b; multiple liquid paths communicating respectively with the multiple ejection openings 3a for supplying the ink; and a common liquid chamber communicating with the liquid paths for ink in common for storing the ink. Note that, hereinafter, a combination of each of the ejection openings with the corresponding liquid path is sometimes referred to as a nozzle. Further, unless otherwise particularly distinguished, the ink and the treatment solution are collectively referred to as a liquid. In the inkjet head 3 of this embodiment, 1280 ejection openings 3a are arranged for every kind of liquid (i.e., for one color ink) in the Y direction that is the conveying direction of print medium, enabling printing at a density of 1200 dpi (dots per inch). The ejection openings for ink are provided in a region 3c on the ejection face in
Refer to
In this example, the two suction recovery mechanisms 7A, 7B are provided, and are driven to be lifted or lowered by the lifting-lowering mechanism. Each of the suction recovery mechanisms 7A, 7B includes a cap (not shown) that is movable between a position where three arrays of the ejection openings are covered (capped) and a position that is away from the ejection face. The cap is capable of performing an operation (suction recovery operation) of forcing a liquid to be discharged by driving a pump (not shown) at the capping position to thereby exert the sucking force to the ejection unit. In other words, the suction recovery operation is an operation of forcibly sucking liquids from the multiple nozzles formed in the inkjet head to refresh the liquids in the nozzles into a condition suitable for ejection.
Moreover, the recovery operation unit 7 of this example is capable of performing preliminary ejection that is ejection of the ink into the receiving box 8 with the inkjet head 3 facing the receiving box 8. Further, the recovery operation unit 7 of this example is provided with the wiping mechanism 9 at an end portion of the movable range of the inkjet head 3 (for example, the home position of the inkjet head). The wiping mechanism 9 is capable of moving a wiping blade 10 while sliding it on the ejection face 3b of the inkjet head 3. Thereby, a liquid mist which differ from main ink droplets ejected from the inkjet head, dust, and the like adhering to the ejection face 3b are wiped off.
The input/output port 104 is used to transmit/receive required data between the main controller 100 or the CPU 101 and each unit to be described below. Hence, the input/output port 104 is connected to driving circuits 105, 106, 107, and 109 that respectively corresponds to a conveyance motor (LF motor) 112, a carriage motor (CR motor) 113, the inkjet head 3, and the recovery operation unit 7. Note that the LF motor 112 is a motor used as a drive source for causing the conveying unit to convey a print medium. The CR motor 113 is a motor used as a drive source for moving the carriage 2 or the inkjet head 3 over a print medium. The driving circuit 107 is a circuit for driving the inkjet head 3 in accordance with the binary print data representing ejecting/not-ejecting ink, while the inkjet head 3 is moving. Further, the driving circuit 109 is a circuit for driving the lifting-lowering mechanism for the cap, a pump activating mechanism, and the wiping mechanism in the recovery operation unit 7.
The input/output port 104 is further connected to: a head-temperature sensor 114 that is a unit for detecting the temperature of the inkjet head; an encoder sensor 110 fixed to the carriage 2; and a temperature-humidity sensor 115 that detects a temperature and humidity which are the environment conditions where the main body 1 is used. In addition to these, for example, a sensor for detecting a leading end and a trailing end of a print medium, a sensor for detecting the distance (gap) between the inkjet head and a print medium, or the like may be connected to the input/output port 104.
Moreover, the main controller 100 or the input/output port 104 is connected to an external device 116 through an interface circuit 111, which allows to transmit/receive various information such as image data to be printed, required control data, and the status of the printing apparatus main body 1. The external device 116 serves as a source of supplying print data to the printing apparatus, and has an appropriate form such as a personal computer, a scanner, and a digital camera.
The input/output port 104 is further connected to a preliminary ejection counter 118, a margin-less print counter 119, an ejection dot counter 120, and a recovery operation counter 121. Here, the preliminary ejection counter 118 counts the number of dots ejected from the nozzle in the preliminary ejection before printing is started, after printing is completed, or during printing. The margin-less print counter 119 counts the number of ink dots ejected to a region outside a print medium, which are necessary for printing with no margin left in at least one edge portion of the print medium (i.e., margin-less printing). The ejection dot counter 120 counts the number of ink dots ejected during printing. The recovery operation counter 121 counts an amount of ink which is forcibly discharged from the inkjet head 3 by the recovery operation unit 7. Note that it is needless to say that the ejection dot counter 120 and the recovery operation counter 121 are updated and managed cumulatively per one replacement cycle in a process to be described later for the purpose of knowing timings of replacing components in the printing apparatus.
Next, description will be given for the outline of the printing operation executed by the inkjet apparatus having the above-described configuration. When print data is received from the external device 116 through the interface circuit 111, the print data is loaded to the buffer of the RAM 103. Then, when a printing operation is instructed, the conveying unit including the LF motor is activated, and a print medium is conveyed to a position facing the inkjet head 3. The carriage 2 is moved in the X direction along the guide shaft 4. During the movement, liquid droplets are ejected from the inkjet head 3, and an image of a band is printed on the print medium. Thereafter, the conveying unit conveys the print medium in the Y direction intersecting the moving direction of the carriage 2 by a predetermined amount (for example, by a band width corresponding to the length of the array of the ejection openings). By repeating these operations of conveying the print medium and of moving the inkjet head, an image is formed on the print medium according to the print data.
Note that the main controller 100 detects the position of the carriage 2 by counting a pulse signal which is outputted from the encoder sensor 110 along with the movement of the carriage 2. Specifically, the encoder sensor 110 detects portions to be detected which are formed at certain intervals in an encoder film 6 (see
As described above, in a situation where such an ink that increases in viscosity along with the evaporation of ink solvent is used more and more, it is highly desirable to know how much the viscosity of mist adhering to each of the components within the main body is increased and to know an appropriate replacement timing for the component. Moreover, the degree of increase in viscosity along with the evaporation of the solvent is different depending on the type of ink used in the printing apparatus. Thus, it is highly desirable to know how much the fixed adhesion is developed and the replacement timing in consideration of this difference.
The carriage moving mechanism reaches its lifetime when ink mist mainly generated during the printing adheres to the guide shaft 4 and the like and thus causes a sliding resistance to the carriage. Accordingly, there is a need to know the amount of ink mist adhering to the guide shaft 4 and the sliding resistance caused by the adhering ink mist. It has been found that the sliding resistance differs greatly depending on the type of ink.
In
In the dot count processing (Step 216), an expected lifetime value of the carriage moving mechanism is calculated based on the dot count values of the respective types of inks . In this embodiment, the expected lifetime value is calculated based on the following formula. Specifically,
Expected lifetime value=(yellow ink ejection amount×yellow ink weight coefficient (=1)+cyan ink ejection amount×cyan ink weight coefficient (=2)+magenta ink ejection amount×magenta ink weight coefficient (=2)+black ink ejection amount×black ink weight coefficient (=4))×ink mist generation rate×ink mist adhesion rate.
In the above formula, each of the amounts of ink ejection is calculated by multiplying the amount of a corresponding ink ejected per one ink dot by the dot count value. The amount of ink ejected per one dot is a known value determined from the ink, the configuration of the head (especially nozzles), and the like. Moreover, the ink mist generation rate is a proportion of the amount of ink which turns into mist to the total amount of ink ejected, and, the ink mist adhesion rate is a proportion of the amount of mist adhering to the guide shaft 4 to the amount of ink which has turned into mist.
It is judged whether or not the expected lifetime value obtained from the above formula exceeds a predetermined threshold (Step 217). If the judgment is positive, an instruction to replace the component is notified to the user (Step 218). On the other hand, if the judgment is negative, the procedure is finished (Step 219). Note that, in a case of giving such an instruction or notification, a display unit or sound generating unit provided in the printing apparatus or in the external device can be used to present the user with information such as which component should be replaced. Note that, in this example, the processing of Steps 216 and 217 correspond to a judgment unit.
As described above, a more accurate lifetime expectation can be made by performing the lifetime expectation based on the viscosities after the evaporation of solvent of the respective types of ink. Thus, instead of a replacement timing of the carriage moving mechanism which is set based on the most sever condition, i.e. ejection of only the black ink, the replacement timing of the carriage moving mechanism is set based on an adequate condition set in consideration of the amounts of consumption of inks of respective colors. For example, compared to the case where the replacement timing of the carriage moving mechanism is set based on the ejection of only the black ink, if inks of all the colors are evenly used, the replacement cycle can be made approximately twice as long. This leads to reduction in the running cost of the printing apparatus.
The second embodiment of the present invention is an example in which additions are made to the first embodiment described above to obtain the ink mist generation rate more accurately. A lifetime expectation formula similar to the first embodiment is also used in this embodiment. However, the ink mist generation rate is made variable depending on the usage condition of the apparatus.
It is known that the ink mist generation rate depends on a distance between an inkjet head 3 and a print medium. In some inkjet apparatuses, the distance between the inkjet head 3 and the print medium, i.e. the height level of the inkjet head 3 with respect to the print medium, can be changed among three levels of, for example, “low”, “medium”, and “high” in accordance with the type of print medium and use environment of the apparatus. Thus, in this embodiment, the ink mist generation rate is changed in accordance with the distance as illustrated in
A third embodiment of the present invention is an example in which the present invention is applied to the lifetime judgment of a movable unit different from that of the first embodiment, particularly of the wiping mechanism 9 of
In this embodiment, as similar to the first embodiment, a formula for judging the lifetime of the wiping mechanism 9 is set as described below in view of degrees of fixed adhesion and increase in viscosity of each type of ink.
Expected lifetime value=(yellow ink preliminary ejection amount×yellow ink weight coefficient+cyan ink preliminary ejection amount×cyan ink weight coefficient+magenta ink preliminary ejection amount×magenta ink weight coefficient+black ink preliminary ejection amount×black ink weight coefficient)×ink mist generation rate×ink mist adhesion rate+(yellow ink's beyond-edge ejection amount in margin-less printing at HP side×yellow ink weight coefficient+cyan ink's beyond-edge ejection amount in margin-less printing at HP side×cyan ink weight coefficient+magenta ink's beyond-edge ejection amount in margin-less printing at HP side×magenta ink weight coefficient+black ink's beyond-edge ejection amount in margin-less printing at HP side×black ink weight coefficient)×ink mist generation rate in margin-less printing at HP side×ink mist adhesion rate in margin-less printing at HP side.
Note that, in the above formula, the weight coefficients for the yellow ink, the cyan ink, the magenta ink, and the black ink were set to “1”, “2”, “2”, and “4”, respectively. The amount of preliminary ejection of each ink is calculated by multiplying the amount of the ink ejected per one dot by the dot count value for the preliminary ejection. The amount of the ink ejected per one dot is a known value determined from the ink, the configuration of the head (especially nozzles), and the like. Moreover, the dot count value of each type of ink for the preliminary ejection is measured by a preliminary ejection dot counter 117. Furthermore, the ink mist generation rate is a proportion of the amount of ink which turns into mist to the total amount of ink ejected in the preliminary ejection, and the ink mist adhesion rate is a proportion of the amount of mist adhering to the rail guide of the wiping mechanism 9 to the amount of ink which has turned into mist.
Meanwhile, “beyond-edge ejection amount in margin-less printing at HP side” of each type of ink is calculated by multiplying the amount of the ink ejected per ink dot by the number of ejections for “beyond-edge ejection amount in margin-less printing at HP side” of the ink. The ink ejection amount per one dot is a known value determined from the ink, the configuration of the head (especially nozzles), and the like. Moreover, the dot count value of each type of ink in the preliminary ejection is measured by the preliminary ejection dot counter 117. Each of the ink ejection amounts is a known value determined from the ink, the configuration of the head, and the like, and the number of ejections for “beyond-edge region in margin-less printing at HP side” of each type of ink is measured by a margin-less print counter 119. Furthermore, ink mist generation rate in “margin-less printing at HP side” is a proportion of the amount of ink which turns into mist to the “beyond-edge ejection amount in margin-less printing at HP side”, and ink mist adhesion rate in “margin-less printing at HP side” is a proportion of the amount of mist adhering to the rail guide of the wiping mechanism 9 to the amount of ink which has turned into mist.
In this embodiment, as similar to the first embodiment, if the expected lifetime value of the wiping mechanism 9 obtained from the above formula exceeds a threshold, an instruction to replace the component is notified to the user. This is because there is a possibility of the wiping mechanism 9 breaking the inkjet head 3 and other components if the wiping mechanism 9 performs wiping despite having reached its lifetime.
As described above, an accurate lifetime expectation can be made on the life time of a moveable unit different from that in the first embodiment, i.e. the wiping mechanism, by performing the lifetime expectation based on the viscosity after evaporation of solvent of each type of ink. As a matter of course, as described in the second embodiment, a control may be added which is performed in accordance with the distance between the inkjet head and the print medium, the inkjet head drive condition, the inkjet head temperature condition, and the like.
In the first embodiment described above, consideration has been made on degrees of adhesion and of increase in viscosity which are different depending on the type of ink. However, it has been found that degrees of adhesion and of increase in viscosity depend also on an environment in which the apparatus is used. Thus, in the fourth embodiment of the present invention, a more adequate lifetime expectation is performed in accordance with the environment in which the apparatus is used.
In this embodiment, in view of difference in tendency of fixed adhesion among the above described use environments, a formula for judging the lifetime of the carriage moving mechanism is set as described below by additionally considering humidity information from a temperature-humidity sensor 115 provided in the apparatus. Specifically,
Expected lifetime value=(yellow ink ejection amount×yellow ink weight coefficient+cyan ink ejection amount×cyan ink weight coefficient+magenta ink ejection amount×magenta ink weight coefficient+black ink ejection amount×black ink weight coefficient)×ink mist generation rate×ink mist adhesion rate.
Note that, the weight coefficient of the yellow ink in humidity lower than 20% is “1”, that in humidity equal to or higher than 20% and lower than 50% is “0.5”, and that in humidity equal to or higher than 50% is “0.25”. Moreover, the weight coefficient of each of the cyan ink and the magenta ink in humidity lower than 20% is “2”, that in humidity equal to or higher than 20% and lower than 50% is “1”, and that in humidity equal to or higher than 50% is “0.5”. Furthermore, the weight coefficient of the black ink in humidity lower than 20% is “4”, that in humidity equal to or higher than 20% and lower than 50% is “2”, and that in humidity equal to or higher than 50% is “1”. In this embodiment, as similar to the first embodiment, if the expected lifetime value calculated from the above formula exceeds a threshold, an instruction to replace the component is notified to the user.
As described above, an even more accurate lifetime expectation can be made by performing the lifetime expectation in accordance with the environment in which the apparatus is used in addition to the tendency of fixed adhesion of each type of ink. Thus, instead of a replacement timing of the carriage moving mechanism which is set based on the most sever condition, i.e. ejection of only the black ink in low humidity condition, the replacement timing of the carriage moving mechanism can be set based on an adequate condition set in consideration of the humidity condition and the consumed ink amounts of respective ink colors. For example, compared to the case where the replacement timing of the carriage moving mechanism is set based on the most sever condition described above, if inks of all colors are evenly used in a high humidity environment, the replacement cycle can be made approximately eight times as long. This leads to reduction in the running cost of the printing apparatus.
As a matter of course, as described in the second embodiment, a control may be added which is performed in accordance with the distance between the inkjet head and the print medium, the inkjet head drive condition, the inkjet head temperature condition, and the like. Moreover, an even finer control can be performed by adding environment conditions such as temperature in addition to the humidity.
The lifetime expectation of the carriage moving mechanism and that of the wiping mechanism have been described separately in different embodiments. However, the above-described embodiments can be combined as appropriate.
Moreover, the present invention is also applicable to lifetime judgment for other moveable units such as a fan which generates an air current for collecting ink mist, a conveyance mechanism for a print medium, and a mechanism for collecting ink which is produced by the preliminary ejection and the suction recovery operation. Furthermore, the present invention is also applicable to lifetime judgment for other components, such as various sensors, which can make the performance of the printing apparatus main body unable to be maintained due to the adhesion of mist. In addition, the types of inks, the number of types of inks, values of coefficients corresponding to the respective types of inks described above are merely examples, and any alternative can be selected as appropriate.
Moreover, the description has been given for the case where the present invention is applied to a so-called serial printing apparatus. However, as a matter of course, the present invention is applicable also to a so-called line printer-type printing apparatus that uses a print head in which ejection openings are arranged across the width of a print medium.
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. 2010-141658, filed Jun. 22, 2010, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-141658 | Jun 2010 | JP | national |
