1. Field of the Invention
The invention relates to an inkjet printing apparatus that uses an inkjet head, and also to a method of controlling the inkjet printing apparatus. Specifically, the invention relates to a technique to effectively remove the mist that is produced when the inkjet head ejects ink.
2. Description of the Related Art
An inkjet head ejects ink directly onto a printing medium from a fine nozzle (hereafter sometimes referred to a unit including an ejection opening, a liquid passage that communicates with the ejection opening and an element to generate energy that is to be used for the ejection of ink). This way of ink ejection sometimes makes the ejected ink bounce off the printing medium, and also generates, in addition to the main mass of ink involved in the actual printing, fine ink droplets (satellites) that are ejected to float in the atmosphere. The bounced back portion of the ink and the floating satellites form ink mists, which sometimes adhere to the portion surrounding the ink-ejection opening of the inkjet head. The ink thus adhered to the surrounding portion of the ink-ejection opening may adversely affects the later action of ejecting ink. Failures of ejection may happen, or color mixture may occur because inks of different colors are mixed together. Consequently, the quality of an image to be printed on the printing medium may deteriorate.
Away of solving the problem is disclosed by Japanese Patent Laid-Open No. H07-195708 (1995). According to the disclosure, the adhered ink is removed by use of a wiping member made of an elastic material such as rubber. The surface of a printing head (hereafter, the surface will be referred to as “ejection face”), in which the ejection openings are formed, is wiped by the wiping member to remove the adhered ink (hereafter, the action of the wiping member will be referred to as “wiping action”). To carry out color printing, an inkjet head may have an array of plural nozzles to eject inks of plural colors. If this is the case, the wiping action may cause inks of different colors to be mixed together on the ejection face. If such color mixture occurs, it is highly possible that the quality of the printed image be unsatisfactory. To address this problem, the apparatus of Japanese Patent Laid-Open No. H07-195708 (1995) performs ejection to discharge inks of predetermined amounts after the wiping action (hereafter, such ejection will be referred to as “a preliminary ejection”), separately from the ejection of inks to actually print an image on a printing medium. While the preliminary ejection leads to an increase in the amount of inks to be wastefully discharged not for printing purpose, Japanese Patent Laid-Open No. H07-195708 (1995) also discloses a technique to suppress such increase due to the preliminary ejection. To this end, the apparatus regulates the number of times of the preliminary ejection on the basis of which kinds of inks have just been used for printing.
In recent years, there have been increasing demands for printing at a faster speed with a higher resolution as well as use of more colors for printing in inkjet printing apparatuses. Such trends lead to increases in the number of ejection openings formed in an inkjet head and in the number of ink colors. Such increases, in turn, tend to increase the amount of inks wastefully discharged in the preliminary ejection. This increase in the wasted inks has called for means of further reducing the wasteful consumption of inks. To this end, a more effective technique has been needed than the technique disclosed in Japanese Patent Laid-Open No. H07-195708 (1995).
Accordingly, an object of the invention is to prevent such inconveniences as ejection failure and color mixture from occurring by the preliminary ejection of inks performed after the wiping. A second object of the invention is to reduce the amount of inks consumed by the preliminary ejection of inks performed after the wiping, by regulating the amount of inks to be used in the preliminary ejection.
In an aspect of the present invention, there is provided an inkjet printing apparatus comprising:
a printing unit configured to printing medium by use of a printing head including an ejection portion in which an ejection opening to eject ink is formed;
a wiper for wiping a face of the printing head, the face having the ejection portion formed therein;
a preliminary-ejection unit performing preliminary ejection of ink from the ejection portion after the wiping by the wiper; and
a regulation unit configured to regulate, in accordance with an amount of printing that has been made since the last wiping, an amount of ink to be ejected in the preliminary ejection.
In another aspect of the present invention, there is provided a method of controlling an inkjet printing apparatus to perform printing using a printing head including an ejection portion in which an ejection opening to eject ink is formed, the method comprising the steps of:
wiping a face of the printing head, the face having the ejection portion formed therein;
performing preliminary ejection of ink from the ejection portion after the wiping; and
regulating, in accordance with an amount of printing that has been made since the last wiping, an amount of ink to be ejected in the preliminary ejection.
According to the invention, the preliminary ejection performed after the wiping can prevent such inconveniences as ejection failure and color mixture from occurring. In addition, the amount of inks used in the preliminary ejection is regulated in accordance with the degree of ink-mist adhesion to the ejection face. What is made possible consequently is a reduction in the amount of inks consumed in the preliminary ejection performed after the wiping.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Some embodiments of the invention will be described in detail below by referring to the drawings.
Recovery mechanisms 30A and 30B are mechanisms to maintain, or recover if necessary, the satisfactory ink-ejection performance of the ejection portions of the printing head 5. In the printing apparatus of the first embodiment, each of the recovery mechanisms 30A and 30B corresponds to three of the six ejection portions, and has caps to cover, respectively, the corresponding three ejection portions. When the printing head 5 is not used, the cap covers the corresponding ejection face (hereafter, a term “capping” will be used to mean the cap's action to cover the corresponding ejection face). By the capping action, the cap is capable of protecting the corresponding ejection portion, or the printing head 5. If an unillustrated pump is driven with the ejection faces capped with their respective caps, a sucking force acting on the ejection portions is generated so as to perform the action of “suction recovery”, which is an action of forcing the inks to be discharged from their respective ejection openings. In addition, with the caps facing their respective ejection portions, the inks can be ejected into their respective caps to perform preliminary ejection. An ink-receptor box 31 is provided to receive inks ejected during the preliminary ejection. A wiping mechanism 32 is provided to carry out the action to wipe the ejection faces of the printing head 5.
In the printing apparatus with the above-described configuration, a printing medium is set at a printing position in accordance with the data on which the printing is carried out. With the printing medium set at the proper printing position, the carriage 1 is controlled so as to move along the guide shaft 33. While the printing head 5 is moving together with the carriage 1, the color inks are ejected from their respective ejection portions. Consequently, a single band of an image which includes letters, pictures, or the like of (a band is a printable area during a single action of moving the printing head 5) is printed on the printing medium. Once the printing for the single band is finished, the printing medium is conveyed, by an unillustrated conveyor unit, in a direction intersecting the moving direction of the carriage 1 by a predetermined distance (i.e., a width of a single band, or a distance corresponding to the width printed by a predetermined number of printing elements). Alternatively, if the inkjet printing apparatus performs printing by what is known as the “multi-pass printing” method (a method of printing an image for a single printing area by moving the printing head 5 plural times), the distance by which the printing medium is conveyed by a single conveying action may be smaller than the above-mentioned predetermined distance.
Encoders 35 are provided along the route that the carriage 1 is moving along. The encoders 35 are used for detecting the position where the moving carriage 1 is currently positioned. To know the current position of the carriage 1, the carriage 1 includes a built-in encoder sensor. When the encoder sensor detects the encoder 35, the encoder sensor sends a signal indicating the detected the encoder 35. The movement of the carriage 1 to its home position is controlled in accordance with the results of detection, carried out using the encoders 35, of the current position of the carriage 1. The recovery mechanisms 30A and 30B, the wiping mechanism 32, and the like are provided near the home position of the carriage 1.
In the first embodiment, the wiping mechanism 32 includes a wiper 32A and a wiper 32B. The wiper 32A is capable of wiping the ejection faces of the ejection portions 5C, 5M, and 5Y. The wiper 32B is capable of wiping the ejection faces of the ejection portions 5Bk, 5PC, and 5PM. To carry out the wiping, the wipers 32A and 32B are moved in the direction indicated by the arrow in
The input-output port 304 is connected to the that driving circuits 305 and 306. The driving circuit 305 drives a conveyor motor (LF motor) 312 that serves as the source of driving force provided to the conveyor system. The driving circuit 306 drives a motor (CR motor) 313 that serves as the source of driving force to move the carriage 1. In addition, the input-output port 304 is connected to the driving circuits 307 and 309. The driving circuit 307 drives the nozzles of the ejection portions of the printing head 5. The driving circuit 309 drives the recovery mechanisms 30A and 30B, and the wiping mechanism 32.
In addition, the input-output port 304 is connected to a home-position sensor 310, a head-temperature sensor 314, a gap sensor 315, and an interface circuit 311. The home-position sensor 310 detects the position that serves as the reference for the control on the movement of the carriage 1 or the printing head 5. In addition, the home-position sensor 310 outputs its detection results that are used when the printing head 5 is set at a position where the recovery mechanisms 30A and 30B, and the wiping mechanism 32 carry out their tasks on the printing head 5. The head temperature sensor 314 detects the temperature of the printing head 5. The gap sensor 315 detects the distance (gap) between the printing head 5 and the printing medium or the platen supporting the printing medium. The interface circuit 311 is used to receive/transmit necessary data from/to an external device (the external device may be provided in an appropriate form, such as a computer, an image scanner, a digital camera, or the like) serving as the source to supply data that the printing to be performed is based upon. A humidity sensor 316 is provided at an appropriate position. The humidity sensor 316 detects humidity that forms a part of the environment under which the printing apparatus is used. Note that the gap sensor 315 and the humidity sensor 316 are elements that are preferably provided in a third embodiment to be described later.
When a wiping action is carried out every time a predetermined unit of prints, e.g., printing on a sheet of printing medium (printing for one page) is finished, the wiping action interposed as such, however, causes various problems. For example, every time the wiping action is carried out, it takes a certain length of time resulting in a lower productivity in the printing. In addition, wiping actions carried out too frequently may shorten the service life of the wipers 32A and 32B. Accordingly, the wiping action should be carried out on a necessary basis. Whether a wiping action is or is not necessary for each page is preferably determined on a basis of the quantity of mist that can adhere to the ejection faces of the printing head 5. The quantity of the mist adhering to the ejection faces of the printing head 5 depends heavily on the amount of ejected inks, or on the number of ink ejections. Accordingly, in the first embodiment, the number of ink ejections for printing performed since the last wiping action is counted (i.e., a dot count is performed). If the counted number of ink ejections reaches a threshold, a wiping action will be carried out.
In the series of processes shown in
It is a known fact that preliminary ejection of inks of a certain amount is preferably carried out every time a wiping action is performed. There are two main reasons for this. Firstly, it is often the case that the mist that adheres to the ejection faces before the wiping increases its viscosity due to evaporation of the solvent component of inks caused by various reasons. For example, the ejection of inks itself causes the evaporation of the solvent component of inks. The airflow caused by the moving carriage 1 also causes the evaporation of the solvent component of inks, and the heat generated around the printing head 5 also causes the evaporation of the solvent component of inks. If such adhered inks with increased viscosity are wiped with the wipers 32A and 32B, the inks with increased viscosity may be forced into the nozzles to clog the nozzles. If such clogging occurs and an ink ejection action for the primary purpose, i.e., action of ejecting inks for actual printing, is carried out for the next time with no preliminary ejection having been performed beforehand, ejection failure may take place. The second one of the above-mentioned two main reasons is related to the mixing of inks of different colors. In the first embodiment, the printing head 5 has a structure with plural ejection portions provided respectively for the plural inks of different colors, and each of the wipers 32A and 32B is assigned to wipe the ejection faces of the corresponding plural inks of different colors. In the case of the first embodiment or the like cases, performing wiping actions may force the ink of one color adhered to its own ejection face into nozzles for the inks of different colors. If this occurs, an action of ejecting inks for the primary purpose (i.e., for actual printing) with no preceding preliminary ejection may cause the mixing of different colors. So, such inconveniences as the above-mentioned ejection failure and the mixing of inks of different colors can be avoided by carrying out preliminary ejection to discharge the inks with increased viscosity or the inks of different colors that have been forced into the nozzles.
Accordingly, some of the conventional inkjet printing apparatuses have carried out preliminary ejection of inks of a predetermined amount after every wiping action. In the first embodiment of the invention, however, the inkjet printing apparatus controls the amount of inks used for the preliminary ejection, or, to be more specific, the number of ink ejections in each occasion of preliminary ejection. The control of this first embodiment is based on the quantity of printing, which affects the degree of adherence of mist to the printing head.
Specifically, the number of preliminary ejections after each wiping action can be controlled, for example, in accordance with the count value obtained by counting the number of sheets that have been printed since the last wiping action. If many sheets have been printed since the last wiping action, a larger amount of mist is likely to have adhered to the ejection faces. In this case, a wiping action is more likely to force more inks with increased viscosity into the nozzles and/or to force more inks into nozzles of different colors. So, the number of preliminary ejections is increased. In contrast, if sheets that have been printed since the last wiping action are not many, a smaller amount of mist is likely to have adhered to the ejection faces. In this case, a wiping action may have forced a smaller amount of inks with increased viscosity into the nozzles and/or may have forced a smaller amount of inks into nozzles of different colors. So, the number of preliminary ejections is decreased.
As has been described thus far, by carrying out preliminary ejection after wiping, the inkjet printing apparatus of this first embodiment can prevent the degradation of printing quality from being caused by the ejection failures and the unintended mixing of inks of different colors. In addition, in accordance with the degree of adherence of mist to the ejection faces of the printing head 5, the inkjet printing apparatus of this first embodiment controls the number of preliminary ejections to be carried out after each wiping action. So, the amount of inks wastefully consumed for the preliminary ejection after the wiping can be reduced. Such reduction can contribute to a reduction of the running cost for the inkjet printing apparatus. Note that, if the control on the preliminary ejections after the wiping is based on the number of printed sheets as in the above-described case, the count value for the printed sheets is to be reset. In addition, the purpose of this first embodiment can be achieved by adjusting, in accordance with the quantity of prints, the amount of inks to be used in the preliminary ejection performed after the wiping. So, the purpose is achieved also by adjusting amount of ink to be ejected in each preliminary ejection action (i.e., the amount of ink of a single droplet).
In addition, a more finely-tuned control may be carried out. For example, as
In this second embodiment, a more finely-tuned control on the number of the preliminary ejections to be performed after each wiping action is executed so as to obtain a larger effect than in the case of the first embodiment. The second embodiment is particularly effective if inks of a larger number of different colors are used.
The inks to be used in the second embodiment are cyan (C), magenta (M), yellow (Y), photo cyan (PC), photo magenta (PM), photo yellow (PY), black (Bk), gray (Gy), photo gray (Pgy), Red (R), green (G), and blue (B).
A wiping mechanism 32 includes wipers 321 to 326. The wipers 321 to 326 are driven to move in the direction indicated by the arrow in
The configuration of the control system and the series of control processes of this second embodiment may be the ones that are similar to their respective counterparts in the first embodiment. In this second embodiment, however, whether a wiping action should or should not be performed and how many preliminary ejections should be performed are determined in the following way.
Inks of many colors are used in this second embodiment. So, a more finely-tuned control on the number of preliminary ejections is executed. Specifically, if the number of dots for one color that have been ejected since the last wiping action differs from the corresponding number for another color, the numbers of preliminary ejections to be performed for the these colors may be different from each other. Such arrangement aims to improve the following points in the first embodiment.
When the number of preliminary ejections to be performed after the wiping is set, the following point should be taken into consideration. Assuming that the largest possible amount of mist adheres to the printing heads, the preliminary ejections of the set number must eliminate the possibilities of ejection failure and of the unintended mixing of different colors caused by the wiping action which forces the inks with increased viscosity into nozzles and which forces the inks of individual colors into wrong nozzles. According to the table shown in
In the first embodiment, however, the 1000 preliminary ejections are set equally for the ejection portions for the inks of all the colors even if only the ink of, for example, yellow has been used to print all the image. If this way of setting the number of preliminary ejections is adopted in this second embodiment, a total of 15360000 preliminary ejections, 15360000=1000 (number of preliminary ejections for each color)×12 (number of colors)×1280 (number of nozzles for each color), must be performed after the wiping of this time irrespective of the image pattern that has been printed.
In the printing of the images that exclusively use the ink of, for example, yellow, the printing heads 52 to 56 eject no inks for printing. Accordingly, little, if any, mist probably adheres to the ejection faces of these printing heads 52 to 56. So, there will be no problem even if a smaller number of preliminary ejections are set for each of the printing heads 52 to 56. For this reason, the apparatus of the second embodiment counts, individually for each color, the dots that have been ejected for printing since the last wiping action. Then, by referring to the table shown in
As has been described thus far, by carrying out preliminary ejection after wiping, the inkjet printing apparatus of this second embodiment can prevent the degradation of printing quality from being caused by the ejection failures and the unintended mixing of inks of different colors. In addition, the inkjet printing apparatus of this second embodiment performs a more finely-tuned control on the number of preliminary ejections to be carried out after the wiping of this time. So, a larger effect of reducing the amount of inks wastefully consumed for the preliminary ejection can be obtained.
In this second embodiment, the counting of dots that have been ejected since the last wiping action is performed for each of the colors (for each of the ejection portions), and the number of preliminary ejections after the wiping action is regulated for each of the colors (for each of the ejection portions). It is, however, possible to count the dots for each of the printing heads, and to regulate the number of preliminary ejections for each of the ejection portions.
A third embodiment of the invention is a case where the number of preliminary ejections after wiping is regulated by taking account of the degree of adherence of mist to the ejection faces and which is affected by factors other than the number of ejected dots.
The regulation of the number of preliminary ejections for each printing head in this third embodiment is more finely-tuned than the regulation in the second embodiment. To this end, the regulation, performed in the second embodiment, of the number of preliminary ejections for each printing head shown in
(The number of preliminary ejections after the wiping)=(The number of preliminary ejections shown in FIG. 7B)×(A coefficient determined in accordance with the distance between the printing heads and the printing medium)×(A coefficient determined in accordance with the environment in which the printing apparatus is used)
Some inkjet printing apparatuses are equipped with a mechanism for lifting carriage (such a mechanism is illustrated in none of the accompanying drawings). An inkjet printing apparatus equipped with such a carriage lifting mechanism is capable of changing the distance between the printing heads and the printing medium. For example, on the basis of the kind of printing medium to be used or of the environmental conditions, or simply by the user's choice, the distance (i.e., the level of the printing heads) can be switched among the following five positions: ‘lowest,’ ‘slightly lower,’ ‘standard,’ ‘slightly higher,’ ‘highest.’
It is a known fact that the larger the distance between the printing heads and the printing medium is, the larger the amount of mist adhering to the printing heads or to the ejection faces tends to be. Such tendency is due to the following reason. As the distance between the printing heads and the printing medium is larger, the particles of the mist such as satellites each of which has a smaller mass or which fly at slower speeds cannot reach the surface of the printing medium. Instead, such particles float within the printing apparatus and eventually adhere to the ejection faces. So, in this third embodiment, the gap sensor 315 is used to detect the distance between the printing heads and the printing medium, and a coefficient (such as ones listed in
In addition, it is also a known fact that the amount of mist adherence varies depending upon the environment in which the printing apparatus is used. To be more specific, the lower the humidity is, the larger the amount of the mist adherence tends to be. Such tendency is due to the following reason. As the humidity becomes lower, the evaporation of the ejected ink is encouraged. Consequently, the mass of each particle of the mist becomes smaller, or the particles of the mist fly at slower speeds. As described above, such particles of the mist cannot reach the surface of the printing medium. Instead, the particles of mist float within the printing apparatus, and are likely to eventually adhere to the ejection faces. So, in this third embodiment, a humidity sensor 316 (see
As has been described thus far, in the third embodiment, the number of preliminary ejections after the wiping is regulated by taking account of the possibility that the mist is made to adhere to the printing heads by factors other than the number of ejected dots. Specifically, such other factors that are taken into consideration are ‘the distance between the printing heads and the printing medium’ and ‘the environment in which the printing apparatus is used (e.g., humidity, in particular)’. Accordingly, similar effects to those obtainable by the first and the second embodiments can be obtained in this third embodiment. In addition, a still larger effect of reducing the amount of inks wastefully consumed for the preliminary ejection can be obtained.
In this third embodiment, the number of preliminary ejections after the wiping is regulated by taking account of both ‘the distance between the printing heads and the printing medium’ and ‘the environment in which the printing apparatus is used.’ Alternatively, only either one of the above-mentioned two factors other than the number of ejected dots may be taken into consideration for the purpose of the regulation. Still alternatively, any factor other than the ones mentioned above may also be taken into consideration. In addition, humidity is not the only environmental condition. Such other conditions as the temperature or the air pressure may be taken into consideration as environmental conditions.
A method of driving a printing head is known as the block driving method. According to this driving method, all the nozzles provided in each ejection portion are not driven at a single timing. Instead, the nozzles are divided into plural blocks each of which has a predetermined number of nozzles, and the blocks of nozzles are driven in a time-division manner, that is, one block after another in a predetermined order. Such construction is particularly advantageous for the following reason. The number of nozzles included in each ejection portion has become larger and larger. Under the circumstances, there is a demand for a reduction in the electric power needed at a single driving timing. The time-division driving is an answer to the demand.
With a certain configuration of printing heads or of ejection portions, the order of driving the blocks may affect the image quality and the adherence of mist. Accordingly, in this fourth embodiment, two different block-driving orders are used respectively for occasions of different printing modes. In addition, the number of preliminary ejections is regulated by taking the block-driving orders into consideration.
Firstly, the block driving in this fourth embodiment will be described. In the fourth embodiment, the 1280 nozzles included in a single ejection portion are divided into 32 blocks each of which has 40 nozzles. Then, the blocks of nozzles are driven in a time-division manner one block after another. Note that each ‘block’ does not include spatially successive nozzles. Instead, each one of the nozzles included in each block is spatially separated from the next one by 31 nozzles. Specifically, counted from an end of the nozzle array, the 1st one, the 33rd one, the 65th one, . . . , and the 1249th one are included in a single block and are driven simultaneously. Then, as
When the 1st to the 32nd nozzles are driven in ‘the block driving order A’, each nozzle is driven after the previous one in the order of arrangement. Specifically, the 1st nozzle is driven first, and subsequently the 2nd nozzle is driven, . . . , and finally the 32nd nozzle is driven. The 33rd to the 64th nozzles are driven in a similar manner, that is, each nozzle is driven after the previous one in the order of arrangement. In this case, there is a large lag (difference in time) between the timing of driving the 32nd nozzle and the timing of driving the 33rd nozzle. The large time lag may cause the ink droplets to land at misaligned positions. The inventors found the fact that the amount of mist adherence in this case with the block driving order AI, however, is smaller than that in the case with ‘the block driving order B’.
In contrast, when the 1st to the 32nd nozzles are driven in ‘the block driving order B’, the nozzles are driven one after another in a discrete order. The 33rd to the 64th nozzles are driven in a similar manner, that is, the nozzles are driven one after another in a similar discrete order. In this case with ‘the block driving order B’, the time lag between the driving of the 32nd nozzle and the driving of the 33rd nozzle is smaller than in the case with ‘the block driving order A’. The inventors found the fact that the amount of mist adherence in this case with ‘the block driving order B’, however, is larger than that in the case with ‘the block driving order A’.
The difference in the amount of mist adherence between cases with different block driving orders is probably caused by the following reason. In the case with ‘the block driving order A’, the pressure in one nozzle is made to fluctuate by the action of ink ejection by the driven, adjacent nozzle. The fluctuation of pressure destabilizes the meniscus immediately before the nozzle ejects ink. The unstable meniscus slows down the speed of ink ejected from the nozzle, so that fewer satellites are produced. Consequently, the amount of mist adhering to the ejection faces is probably reduced. In contrast, in the case with ‘the block driving order B’, the meniscus in one nozzle immediately before the nozzle ejects ink is stable because the nozzle is less likely to be affected by the ink ejection from the driven, adjacent ink. Accordingly, the ink is ejected from the nozzle at a faster speed, so that more satellites are produced. Consequently, the amount of mist adhering to the ejection faces is probably increased.
By taking such characteristics into consideration, the printing apparatus of this fourth embodiment sets the poster/photo mode and the line-image mode as follows. In the poster/photo mode, ‘the block driving order A’ is adopted, and the multi-pass printing is performed with a larger number of passes in order to obscure the dot misalignment due to the ejection-timing differences. In the line-image mode, the multi-pass printing is performed with a smaller number of passes (the printing may be performed even with a single pass), and ‘the block driving order B’ is adopted, because the dots landed at misaligned positions due to the ejection-timing differences are less noticeable if ‘the block driving order B’ is adopted.
The number of preliminary ejections after the wiping in this fourth embodiment is calculated by taking account of the conditions examined in the third embodiment and the difference in the amount of mist adherence caused by the difference in the block driving order. Specifically, the number of preliminary ejections after the wiping in this fourth embodiment is calculated by the following formula. Note that examples of coefficients determined in accordance with the block driving order are shown in
(The number of preliminary ejections after the wiping)=(The number of preliminary ejections shown in FIG. 7B)×(A coefficient determined in accordance with the distance between the printing heads and the printing medium)×(A coefficient determined in accordance with the environment in which the printing apparatus is used)×(A coefficient determined in accordance with the block driving order)
As has been described thus far, in the fourth embodiment, the number of preliminary ejections after the wiping is regulated by taking account also of the possibility that the mist is made to adhere to the printing heads by the following, additional factors. Specifically, such additional factors that are taken into consideration include ‘the distance between the printing heads and the printing medium’ and ‘the environment in which the printing apparatus is used (e.g., humidity, in particular).’ In addition, another additional factor is the ‘block driving order’. Accordingly, similar effects to those obtainable by the first to the third embodiments can be obtained in this fourth embodiment. In addition, a still larger effect of reducing the amount of inks wastefully consumed for the preliminary ejection can be obtained.
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. 2009-133355, filed Jun. 2, 2009, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2009-133355 | Jun 2009 | JP | national |