JP2010137409A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize moistening in a cap by delivery even when an evaporating rate of ink in an ink tank is increased. <P>SOLUTION: When water content of the ink is evaporated, the amount of delivery of preliminary delivery performed in the cap is set from the water content of the ink. In addition, when there exist a plurality of the ink tanks, the preliminary delivery is performed by using the ink with the highest water content. It is possible thereby to make the inside of the cap under a moistened condition by an appropriate amount of delivery of the ink, and to decrease the amount of waste ink. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus capable of mounting a recording head having a cap for capping a discharge port of the recording head.

  An ink jet recording apparatus performs recording by ejecting ink from a recording head in which ejection openings are formed. Since high-speed recording and recording on various recording media are possible and noise is hardly generated in recording, it is widely used in printers, copiers, facsimiles, and the like.

  Further, since the ink jet recording apparatus consumes ink when recording, it is necessary to supply ink from an ink tank which is an ink storage unit to an ink chamber inside the recording head. The ink tank is located at a different location from the recording head, and a system that supplies ink using a tube or the like, or a cartridge system that is mounted on a carriage as a single ink tank or integrated with the recording head is used.

  On the other hand, ejection defects occur due to the evaporation of water in the ink from the ejection port of the recording head and the vicinity thereof, resulting in thickening. On the other hand, a capping mechanism is known in which, during a non-recording operation in which ink is not discharged, the discharge port surface of the recording head is covered and sealed to prevent ink moisture evaporation from the discharge port.

  Furthermore, as a device for preventing the inside of the cap covering the ejection port from being further dried, a method of arranging an ink absorbing material (ink holding member) in the cap is known (see Patent Document 1).

  On the other hand, when the cap is kept open to the atmosphere for a long time due to a continuous printing operation for a long time, the ink of the ink absorbing material in the cap evaporates. On the other hand, a method is known in which a plurality of types of ink are ejected from the recording head equally at the end of recording, and the ink absorbing material is impregnated with new ink to recover the wet state in the cap. At this time, ink is ejected according to the frequency of ink use (see Patent Document 2).

Further, there is known a method for recovering clogging of a discharge port of a head by capping using this wet state (see Patent Document 3).
JP 2001-96756 A JP-A-2005-280174 JP-A-2005-313114

  The above-described ink tank is provided with an air communication port for introducing air when ink is consumed. Since this atmosphere communication port communicates with the outside air, even if the discharge port surface of the recording head is capped, the water in the ink tank evaporates little by little. When the cap is left for a long time, the moisture content in the ink tank decreases due to evaporation, so that the amount of water in the ink discharged to the ink absorbing material in the cap after being left decreases. In particular, when the remaining amount of ink is small, the water content decreases significantly, and even when the same amount of ink as before evaporation is ejected to the absorbent in the cap, a sufficient wetting effect cannot be obtained. For this reason, in order to obtain a wetting effect equivalent to that before the evaporation of moisture, it is necessary to increase the amount of ink ejected to the absorbent material.

  On the other hand, the amount of ink ejected into the cap is preferably as small as possible because it is an ink that is not used for printing, although the cap is in a wet state. When the amount of ink discharged from multiple types of ink into the cap is increased equally according to the evaporation of ink moisture, ink with low moisture content consumes ink despite its low wetting effect. End up.

  The present invention has been made in order to solve the above-described problem, and can suppress the increase in the amount of waste ink discharged into the cap and can obtain the same wetting effect as before the ink moisture evaporates. An object is to provide an ink jet recording apparatus.

  The present invention has been made in view of this point, and includes a plurality of ink tanks for supplying ink to a recording head having a discharge port surface on which a plurality of discharge ports for discharging ink are formed. An ink jet recording apparatus, comprising: a cap for capping the ejection port surface; and control means for controlling the amount of ink ejected into the cap, wherein the control means comprises the plurality of ink tanks. Among them, the control is performed so that the ink in the ink tank containing the ink having the highest moisture content is discharged into the cap in the largest amount.

  According to the present invention, by controlling the amount of preliminary ejection performed in the cap in accordance with the change in the water content due to the evaporation of the water in the ink tank, the water in the ink is evaporated while suppressing an increase in the amount of waste ink. Provided is an ink jet recording apparatus capable of obtaining the same wetting effect as before.

(First embodiment)
4 to 6 show a recording head that can be mounted on the ink jet recording apparatus according to the present embodiment. Hereinafter, each component will be described with reference to these drawings.

  In FIG. 4, the recording head H1001 has an integrated ink tank, and each ink tank contains color ink (cyan ink, magenta ink, yellow ink). Hereinafter, the recording head H1001 equipped with this ink tank is also referred to as a recording head cartridge. The recording head cartridge is fixedly supported by positioning means and electrical contacts of a carriage 702, which will be described later, and is detachable from the carriage 702, and is replaced when ink is consumed.

<Recording head>
The recording head H1001 in this embodiment uses an electrothermal converter that causes film boiling in response to an electrical signal with respect to ink, and is a so-called side that is disposed so that the electrothermal converter and the ink discharge port face each other. This is a shooter type recording head. The recording head H1001 is for ejecting ink of three colors, cyan, magenta, and yellow. As shown in FIG. 5, the recording element substrate H1101, an electric wiring tape H1301, an ink supply holding member H1501, filters H1701 to H1703, ink absorbers H1601 to H1603, a lid member H1901, and a seal member H1801 are included. The lid member H1901 has a narrow opening H1911 and a fine groove H1921, and the atmosphere communication port H1925 (FIG. 4) is formed by covering with a seal member H1801.

  FIG. 6 is a partially broken perspective view for explaining the configuration of the printing element substrate H1101, and three ink supply ports H1102 for cyan, magenta, and yellow are formed in parallel. Electrothermal conversion elements H1103 and discharge ports H1107 are arranged in a row in a staggered manner on both sides of each ink supply port H1102. FIG. 6 is a schematic diagram of a recording element substrate H1101 using a Si substrate. On the recording element substrate H1101, an electrode portion H1104 such as an electric wiring, a fuse, or a resistor is formed. Then, an ink flow path wall H1106 and a discharge port H1107 are formed on the resin material by a photolithography technique. A bump H1105 such as Au is formed on the electrode portion H1104 for supplying power to the electrical wiring.

  FIG. 7 shows a perspective view of the ink jet recording apparatus of the present embodiment with the exterior part removed. The inkjet recording apparatus includes an automatic feeding unit 701 that feeds the recording mediums that are placed one by one, and a conveyance unit 705 that conveys the fed recording medium along a predetermined path. Yes. A carriage 702 is supported on the conveyance path of the recording medium. The carriage 702 can be reciprocated by a carriage shaft 706 in a direction perpendicular to the recording medium conveyance direction.

  The recording head cartridge can be attached to and detached from the carriage 702 as described above, and can be easily switched between the mounted state and the detached state by operating the head set lever 703. In a state where the recording head is mounted on the carriage 702, the ejection port surface of the recording element substrate H1101 faces downward in FIG. 7 so as to face the recording medium to be conveyed. At one end of the reciprocation path of the carriage 702, a recovery system unit 704 that performs a recovery operation is provided at a position facing the discharge port surface of the recording element substrate H1101. In this recording apparatus, scanning of the carriage 702 and operations of the automatic feeding unit 701, the conveying unit 705, and the recovery system unit 704 are performed by the output of the motor shaft 707.

  As shown in FIG. 8, the recovery system unit 704 includes a cap 801 that seals the ejection port surface of the recording element substrate H1101, and suction recovery means that sucks the inside of the cap. An ink holding member 802 made of a porous absorber is provided inside the cap 801. The cap 801 can move in the horizontal direction via a drive motor (not shown) and can cap the discharge port surface. The suction recovery means appropriately performs a suction recovery operation for sucking ink near the ejection port in the capped state and simultaneously removing bubbles and dust.

  In this embodiment, the porous absorbent body is wetted by discharging ink to the ink holding member 802 in the cap 801. Then, it has the structure left to stand in the state (henceforth a cap closed state) which sealed the discharge outlet with the cap.

  In this embodiment, there is no difference in the moisture content of each ink at the mounting stage of the recording head cartridge, and the moisture ratio at the mounting stage is α. Further, the optimum amount of water for the ink that sufficiently wets the inside of the cap is an amount obtained by ejecting 15,000 inks having a moisture content α.

  FIG. 1 is a table showing the relationship between the cap leaving period created based on the experimental results when leaving the cap and the amount of water evaporated in the ink tank. When the cap is left unattended, the water in the ink in the ink tank from the atmosphere communication port H1925 or the ejection port evaporates little by little. As shown in the table, the longer the cap leaving period, the higher the water evaporation rate of the ink in the ink tank. In addition, when the ink tank is left for the same period, if the remaining amount of ink in the ink tank is small, the water evaporation rate becomes higher than that of the case where the remaining amount of ink is large.

  FIG. 2 is a flowchart showing a sequence when the recording head cartridge is mounted. First, the recording head cartridge integrated with the ink tank is attached (S100). In the recording head cartridge in which the recording head and the plurality of ink tanks are integrated as in this embodiment, the mounting time of the recording head cartridge is the mounting time of the ink tank. Then, X ink is discharged from each ink into the cap. At this time, as described above, there is no difference in the moisture content of each ink in the mounting stage of the recording head cartridge, the moisture content is α, and the optimal moisture content for wetting the inside of the cap is the ink with the moisture content α. The amount discharged 15000 times. Therefore, when each ink is discharged 5000 times to the ink holding member in the cap, an optimal amount of water can be obtained (S101). Thereafter, the discharge port is sealed with the cap 801, and the cap is closed (S102).

  After the cap is closed in S102, the time is acquired from an external device or the like, and stored in the storage memory as the cap close start time Ta (S103). Examples of main external devices connected to the ink jet recording apparatus include personal computers and digital cameras that are host computers that transmit recording data to the ink jet recording apparatus. Almost all such external devices have a clock function, and the user can set the time. Further, the time information may be acquired by using such a clock function of the external device, or the inkjet recording apparatus itself may have a clock element and acquire time information therefrom. After that, it is left in the cap closed state (cap leaving) and waits for the input of a print command (S104). When a print command is input (S105), the current time Tb is obtained by the method described above (S106). The elapsed time TA in the cap closed state is calculated from the current time Tb and the time Ta stored in the storage memory in S103.

  Here, in this embodiment, it is assumed that after the recording head cartridge is attached, the elapsed time TA in the cap closed state is 1 minute and a print command is input. The initial ink amount is 5 g, and no ink is ejected at this time, so the remaining amount of ink is 5 g.

  In FIG. 1, when the remaining amount of ink is 5 g and the TA is less than one month, the water evaporation rate is determined to be 0%. Therefore, the moisture content of each ink remains α. The determination of the ink moisture content is made based on the ink moisture evaporation rate corresponding to the remaining ink amount and the elapsed time in the cap closed state (S107). The ink moisture content calculated here is stored in a storage memory.

  Thereafter, the number of ejections to be ejected into the cap is determined based on the moisture content obtained in S107 (S108). As described above, when the water content of the ink that optimally wets the inside of the cap is the amount of ink that has been discharged by 15000 times, the water content of all three colors is α as in this embodiment. Discharges so that the total number of the three colors is 15000. In the present embodiment, since the moisture content of each color is the same, 5000 shots of each color may be discharged, or 15000 shots of one color (for example, only cyan) may be discharged.

  Thereafter, the cap 801 is separated from the discharge port surface (cap open), and printing is performed (S109, 110). At this time, 1 g of cyan ink, 2 g of magenta ink, and 3 g of yellow ink are used. Although the ink remaining amount of each color varies due to printing, the moisture content of each color remains the same. When printing is completed, the number of shots determined in S108 is discharged into the cap. At this time, the amount of ink to be ejected is determined based on the moisture content of the ink as described above, and the inside of the cap can be optimally wetted. Thereafter, the current time Tc necessary for obtaining the elapsed time until the next printing is acquired and stored in the memory (S113). Then, the cap is left unattended and this sequence is terminated until the next print command is input (S114, 115).

  FIG. 3 is a flowchart showing a sequence when a print command is input to the recording head cartridge left in the cap closed state through the above-described operation. When a print command is input (S200), the current time Td is acquired, and the elapsed time TB of the cap closed state is calculated from Tc stored at the start of cap closing (S113 in FIG. 2). In the present embodiment, it is assumed that two months have elapsed from the cap close start time Tc, and TB is two months. Then, the remaining ink amount information determined based on the dot count information or the like is acquired (S202). In this embodiment, cyan ink 1g, magenta ink 2g, and yellow ink 3g are used in the above-described printing, so that the remaining amount of ink is 4g for cyan ink, 3g for magenta ink, and 2g for yellow ink.

  From the TB obtained in S201 and the ink remaining amount obtained in S202, the moisture content of each ink is determined and stored in the memory (S203). At this time, since the cyan ink was left in a cap for 2 months with a remaining amount of 4 g, the water evaporation rate of the ink during this period is 2.0% from FIG. Since the moisture content before leaving the cap is stored as α in S107 of FIG. 2, the moisture content of the cyan ink at this time is 0.980α in which 2.0% is evaporated from the moisture content α.

  Similarly, since the magenta ink was left in the cap with a remaining amount of 3 g for 2 months, the water evaporation rate of the ink during this period was 2.7%, and the water content of the magenta ink at this time was 0.2%. 973α. Similarly, since the yellow ink was left in a cap with a remaining amount of 2 g for 2 months, the ink evaporation rate during this period was 4.0%, and the moisture content of the yellow ink at this time was 0.960α. is there. Accordingly, cyan ink, magenta ink, and yellow ink are selected from the three colors having the higher moisture content.

  Next, the number of shots discharged into the cap is determined (S204). Using cyan ink with a water content of 0.980α, magenta ink with a water content of 0.973α, and yellow ink with a water content of 0.960α, the number of shots required to achieve the same amount of water as 15000 inks with a water content of α Is as follows. If three colors of ink are ejected at the same number of times, the average ink moisture content is 0.971α, so the total number of ink ejections of three colors is about 15447 (= 15000α / 0.971α). If only cyan ink is used, the number is about 15306 (= 15000α / 0.980α). Similarly, when only magenta ink is used, it is about 15416 (= 15000α / 0.973α), and when only yellow ink is used, it is about 15625 (= 15000α / 0.960α). In other words, the amount of ink discharged for optimally wetting the inside of the cap can be minimized when only cyan ink having the highest ink moisture content is discharged among the inks. Decide to discharge the shot.

  Thereafter, the cap is opened and printing is performed (S205, 206). When printing is completed, the cyan ink 15306 determined in S204 is ejected into the cap, and the cap is closed (S207, 208). Then, the current time Td necessary to obtain the elapsed time until the next printing is acquired and stored in the storage memory (S209). The cap is left unattended, and this sequence is completed in preparation for the next print command (S210, S211).

  As described above, in this embodiment, in order to optimally wet the cap with a smaller discharge amount, when there are a plurality of inks, control is performed so that preliminary discharge is performed in the cap using the ink having the highest moisture content of the ink. It is characterized by doing.

(Other embodiments)
In the case of the first embodiment, preliminary ejection was performed using only the ink in the ink tank containing the ink with the highest moisture content, but the ink with the highest moisture content was taken into consideration in consideration of the remaining amount of ink. Ink other than the ink tank may be supplementarily used. For example, when the remaining amount of the ink tank of the ink having the highest moisture content is small, the preliminary ejection is performed using the ink of the other ink tank having the largest remaining amount. The ink tank may be configured to prevent ink shortage in an ink tank with a small remaining amount by ejecting the most ink in the ink tank having the highest moisture content and ejecting ink in another ink tank. The plurality of ink tanks may not be different colors, and may be a form in which a plurality of ink tanks of the same color are mounted.

  As described above, the same wetting effect as before evaporation can be obtained by controlling the amount discharged into the cap in accordance with the change in the moisture content due to the evaporation of moisture in the ink tank. At this time, by using the most ink in the ink tank having the highest moisture content, a sufficient wetting effect can be obtained while suppressing an increase in the amount of waste ink. Furthermore, by discharging only the ink in the ink tank having the highest moisture content, the amount of waste ink can be reduced as compared with the case of discharging the ink in a plurality of ink tanks.

Table of ink evaporation rate according to ink remaining amount and cap leaving time in this embodiment Flowchart showing a sequence when the recording head cartridge is mounted in the present embodiment. Flowchart at the time of printing command input in this embodiment External view of recording head in this embodiment Exploded view of recording head in this embodiment The perspective view in which the recording element substrate in the present embodiment was partially broken External view of ink jet recording apparatus according to this embodiment Schematic diagram of recovery system unit in this embodiment

Claims (3)

An ink jet recording apparatus capable of mounting a plurality of ink tanks for supplying ink to a recording head having a discharge port surface on which a plurality of discharge ports for discharging ink are formed,
A cap for capping the discharge port surface;
Control means for controlling the amount of ink ejected into the cap,
The ink jet recording apparatus, wherein the control means controls the ink tank containing the ink having the highest moisture content among the plurality of ink tanks to discharge the ink into the cap in the largest amount. An ink jet recording apparatus capable of mounting a plurality of ink tanks for supplying ink to a recording head having a discharge port surface on which a plurality of discharge ports for discharging ink are formed,
A cap for capping the discharge port surface;
Control means for controlling the amount of ink ejected into the cap,
The ink jet recording apparatus, wherein the control unit performs control so that only the ink in the ink tank containing the ink having the highest moisture content among the plurality of ink tanks is ejected into the cap. An ink jet recording apparatus capable of mounting an ink tank for supplying ink to a recording head having a discharge port surface on which a plurality of discharge ports for discharging ink are formed,
A cap for capping the discharge port surface;
Control means for controlling the amount of ink ejected into the cap,
The ink jet recording apparatus, wherein the control unit controls an ejection amount of ink ejected into the cap in accordance with a moisture content of ink in the ink tank.

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