JP2006240173A - Inkjet recorder and pre-ejection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deposition or the like of ink ejected to a pre-ejection receiver in an inkjet printer. <P>SOLUTION: For example, when an ink Bk1 is ejected in a pre-ejection A1, 200 shots of pre-ejection is made by a recording head for the ink Bk1. 400 shots of pre-ejection are made for each of color inks C, Lc, M, Lm and Y as the inks other than the ink Bk1 in this pre-ejection mode Bk1. By employing the above method, when the ink Bk1 and the color ink are ejected to the pre-ejection receiver and mixed in the pre-ejection A1 executed as above, the mixture can be prevented from exceeding a flow limit. In other words, the 400 shots of ejection of a pre-ejection mode Color is set as a value not allowing at least the mixture to exceed the flow limit even if the ink is mixed with the 200 shots of the ink Bk1 of the pre-ejection mode Bk1. Therefore, the ink is prevented from depositing on the pre-ejection receiver due to increase in viscosity caused by evaporation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus that performs recording using a recording head that discharges ink, and a preliminary ejection method in the apparatus, and more particularly to control of preliminary ejection performed in order to keep the ejection performance of the recording head good. It is.

  In an ink jet recording apparatus such as an ink jet printer, a recovery process is generally performed to maintain good discharge performance of a recording head that discharges ink. The water is evaporated from the ejection port of the recording head and the ink inside the recording head, and the ink is thickened (increased in viscosity) or dried. This thickening or drying is a factor in the deterioration of the ejection performance of the recording head. The deterioration of the discharge performance appears as a decrease in which the discharge amount becomes smaller than the normal one or the discharge direction deviates from the normal direction. If this deterioration is significant, ejection may be lost. The recovery process is mainly performed in order to prevent or eliminate thickening, which is the main cause of the deterioration of the discharge performance. As a mode of this recovery process, suction is performed in a state where the surface of the recording head where the ejection ports are arranged is capped and suction is performed to discharge the ink from the ejection port, and ink is ejected without being involved in recording at a predetermined location of the recording apparatus. Preliminary ejection for discharging ink in the mouth is known.

  Incidentally, the recovery process described above may be controlled according to the type of ink used. For example, Patent Document 1 describes that the recovery process is changed according to the combination of inks used. Specifically, it is disclosed that when performing suction recovery, the number of executions is minimized to prevent mixing of different types of inks that are harmful in capping. Japanese Patent Application Laid-Open No. 2004-228561 describes that the recovery process is controlled so as to prevent adverse effects caused by mixing different types of ink accompanying the replacement of the ink to be used. For example, when using low-density ink, increase the number of preliminary ejections to suppress ink density fluctuations and reduce the effect on the image. When using low-density inks, preliminary ejection Shorten the interval to reduce ink density fluctuations and reduce the effect on the image.When using low density ink, increase the number of preliminary ejections after cleaning the front of the print head to increase the ink density. It is disclosed that the fluctuation is suppressed and the influence on the image is reduced.

Japanese Patent Laid-Open No. 07-068797 JP-A-10-006527

  However, even if the recovery process as disclosed in Patent Documents 1 and 2 is controlled and mixing of different types of inks is prevented, the ink itself that is relatively easy to thicken due to the characteristics of the ink is discharged by the recovery process, for example. It cannot be prevented from accumulating or staying in the middle of the ink discharge path. In particular, in the case of preliminary ejection, the ink ejected to the preliminary ejection receptacle for receiving the ejection is generally guided to a predetermined waste ink reservoir by gravity regardless of any power provided in the apparatus. For this reason, the thickened ink does not move in the middle of the discharge path or the like, and the accumulation becomes remarkable. If the above accumulation occurs, the discharge of ink during the subsequent recovery is hindered, and as a result, the discharge path is blocked, resulting in contamination of the apparatus due to overflow of waste ink and a decrease in the life of the apparatus. There is.

  On the other hand, one preliminary ejection receiver is usually provided for a plurality of recording heads used in the apparatus, that is, for a plurality of types of ink used. In this case, different types of ink ejected to the preliminary ejection receptacle are mixed in the preliminary ejection receptacle.

  The present invention has been made in order to solve the above-described problems such as accumulation, and the object of the present invention is that the different types of ink are mixed in the preliminary discharge receiver and are discharged to the preliminary discharge receiver. An object of the present invention is to provide an ink jet recording apparatus and a preliminary discharge method that can prevent ink accumulation and the like.

  Therefore, in the present invention, there is provided an ink jet recording apparatus that performs recording using a recording head that discharges a plurality of types of inks having different degrees of thickening. The preliminary discharge receiver and the preliminary discharge receiver from the recording head A means for performing preliminary ejection by ejecting a plurality of types of ink, wherein the degree of viscosity increase from the first ink with respect to the number of ejections of the first ink having a higher degree of viscosity increase among the plurality of types of ink. And a preliminary ejection means for ejecting the first ink and the second ink by increasing the number of ejections of the second ink having a low value.

  In another aspect, there is provided an inkjet recording apparatus that performs recording using a recording head that discharges a plurality of types of inks having different degrees of thickening, and the preliminary ejection receiver and the plurality of the plurality of inks from the recording head to the preliminary ejection receiver. A means for performing preliminary ejection by ejecting different types of ink, and of the plurality of types of ink, the first color having a higher degree of viscosity than the first color is different from the first color. The first preliminary ejection mode for ejecting the third ink of the second color, which has a lower degree of thickening than the first ink of the first color, and the degree of thickening of the second color than the first ink of the first color A second preliminary ejection mode for ejecting the second ink of the low first color and the third ink of the second color is executed, and the number of ejections of the first ink of the first color is set to the number of ejections of the second ink of the first color. More than the number of ejections and the number of ejections of the first ink of the first color The second color third ink by increasing the number of discharges of, characterized in that comprises a, and preliminary discharge means for performing the first preliminary discharge mode or the second preliminary discharge mode.

  Further, a preliminary ejection method in an inkjet recording apparatus that performs recording using a recording head that ejects a plurality of types of inks having different degrees of thickening, the step of preparing a preliminary ejection receiver, and for the preliminary ejection receiver, A step of performing preliminary ejection by ejecting the plurality of types of ink from the recording head, the first ink having a higher degree of thickening of the plurality of types of ink than the first ink; And a preliminary ejection step of ejecting the first ink and the second ink by increasing the number of ejections of the second ink having a low degree of thickening.

  In another aspect, a preliminary ejection method in an ink jet recording apparatus that performs recording using a recording head that ejects a plurality of types of inks having different degrees of thickening, the step of preparing a preliminary ejection receiver, and the preliminary ejection receiver On the other hand, in the step of performing preliminary ejection by ejecting the plurality of types of ink from the recording head, the first color of the first color having a higher degree of thickening than the first color among the plurality of types of ink. A first preliminary ejection mode for ejecting a third ink of a second color having a lower degree of thickening than the first ink of the first color for the second color different from the first color of the ink; and the first color of the first color A second preliminary ejection mode for ejecting the second ink of the first color and the second ink of the second color, which has a lower degree of thickening than one ink, and the number of ejections of the first ink of the first color is set to From the number of ejections of the second ink of the first color And a preliminary ejection step of executing the first preliminary ejection mode or the second preliminary ejection mode by increasing the ejection number of the second ink of the second color from the ejection number of the first ink of the first color. It is characterized by having.

  According to the above configuration, when ink having a high degree of thickening is ejected, a large amount of ink having a lower degree of thickening is ejected. It is possible to suppress the thickening of the ink having a high degree.

  As a result, it is possible to prevent accumulation of ink discharged to the preliminary discharge receiver.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is a perspective view showing an ink jet printer according to an embodiment of the present invention.

  The printer according to this embodiment includes black (Bk), cyan (C), light cyan (Lc), magenta (M), and light magenta (Lm) and yellow (Y ) Recording heads (not shown) corresponding to the six colors of ink. These recording heads are detachably mounted on a carriage 701 that can move along a guide shaft 708. A flexible substrate 702 for supplying a signal pulse for ejection driving, a head temperature adjustment signal, and the like to the recording head is attached to the carriage 701. The other end of the flexible substrate is connected to a printed circuit board (not shown) provided with a control circuit that executes control of the printer. As will be described later with reference to FIG. 3, the ink is supplied to the recording head from an ink supply tube 703 attached to the flexible base, independently from each color from a tank unit (not shown) that stores the six colors of ink. . Further, a recovery unit (not shown) for performing a recovery process of the recording head is provided in a part of the movement range of the carriage 701. The recovery unit includes a cap that covers the discharge port surface of the recording head, a preliminary discharge receiver, which will be described later with reference to FIG. 10, a blade for wiping the discharge port surface, and the like.

  The recording operation based on the above configuration is performed as follows. A recording medium 705 such as recording paper is supplied to a recording area on the platen 706 by a paper feed roller 704. The recording head ejects ink at a timing based on the position signal obtained by the encoder 707 as the carriage 701 moves. Recording is performed on a recording medium by repeating this recording head scanning and feeding a predetermined amount of paper.

  As the water-soluble organic solvent used in the ink of the present embodiment, any water-soluble organic solvent that has been used in conventionally known inks can be used. Specifically, alkyl having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol. Alcohols; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene Oxyethylene or oxypropylene addition polymers such as glycol, polyethylene glycol, polypropylene glycol; ethylene glycol, propylene group Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as coal, trimethylene glycol, butylene glycol, 1,2,6-hexanetriol, hexylene glycol; thiodiglycol; glycerin; ethylene glycol monomethyl (or Lower alkyl ethers of polyhydric alcohols such as ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl) Lower dialkyl ethers of polyhydric alcohols such as ether; sulfolane, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. The content of the water-soluble organic solvent as described above is generally in the range of 1 to 49%, preferably 2 to 30% by weight with respect to the total weight of the ink. The water-soluble organic solvents as described above can be used alone or as a mixture, but the most preferable liquid-medium composition in the case of having a medium is at least one water-soluble high-boiling organic solvent such as diethylene glycol, triethylene. It contains a polyhydric alcohol such as glycol or glycerin. If necessary, a metal salt such as magnesium nitrate, calcium nitrate, or barium nitrate may be used to improve the recording quality.

  The ink of this embodiment using the above solvent is six types of inks of C, M, Y, Lc, Lm, and Bk as described above. Furthermore, in the present embodiment, Bk (black) is used by exchanging it according to an image to be recorded with two types of Bk. Specifically, the ink is replaced by replacing the ink tank as will be described later. These two types of Bk can be distinguished by the degree of thickening. In the following, a black ink with a relatively high degree of thickening is designated as Bk1, and a black ink with a lower degree of thickening is designated as Bk2. As is well known, such a difference in the degree of thickening occurs depending on the type, characteristics, content, etc. of the color material such as a pigment or dye. Both the inks Bk1 and Bk2 used in the present embodiment use pigments as color materials, but have different degrees of thickening as described above. In addition, the color inks of C, M, Y, Lc, and Lm are all less viscous than the ink Bk1. Preliminary ejection control according to the embodiment of the present invention, which will be described later with reference to FIG. 12 and the like, is performed using the fact that the degree of thickening of the color ink is different from that of the Bk1 ink. As described above, the present invention can be applied to preliminary ejection of a recording head that ejects ink according to the difference in the degree of thickening of the ink regardless of the content and amount of the components constituting the ink such as color materials. is there. This point is also clear from the following description.

  FIG. 2 is a block diagram mainly showing a control configuration of the printer shown in FIG. In FIG. 2, reference numeral 101 denotes a programmable peripheral interface (hereinafter referred to as PPI), which receives a recording information signal including a command signal (command) and recording data sent from the host computer 100 and transfers it to the MPU 102. The printer status information is sent to the host computer 100 as necessary. In addition, input / output is performed with respect to the console 106 having a setting input unit for the user to make various settings for the printer and a display unit for displaying a message to the user, and the carriage 701 or the recording head 9 is also used as a home. A signal input from the home position sensor 107 that detects the position is received. The home position sensor 107 detects that the carriage on which the recording head 112 is mounted has reached the home position.

  An MPU (microprocessing unit) 102 controls each unit in the printer according to a control program corresponding to processing procedures described later with reference to FIGS. 7 to 9 stored in the control ROM 105. Reference numeral 103 denotes a RAM that stores received signals or is used as a work area of the MPU 102 and temporarily stores various data. Reference numeral 104 denotes a font generation ROM which stores pattern information such as characters and records corresponding to the code information, and outputs various pattern information corresponding to the input code information. Reference numeral 121 denotes a print buffer for storing the recording data expanded in the RAM 103 or the like, and has a capacity for recording M rows. In addition to the control program, the control ROM 105 can store fixed data corresponding to a table or the like described later with reference to FIG. These units are controlled by the MPU 102 via the address bus 117 and the data bus 118.

  Reference numeral 113 denotes a capping motor, which serves as a drive source for raising and lowering the cap 27, moving the wiper holder 23, and operating the pump 29 in the recovery unit described above with reference to FIG. Reference numerals 114, 115, and 116 denote motor drivers for driving the capping motor 113, the carriage motor 3, and the paper feed motor 5 in accordance with the control of the MPU 102, respectively.

  Reference numeral 109 denotes a sheet sensor that detects the presence or absence of a recording medium, that is, whether or not the recording medium has been supplied to a position where recording by the recording head is possible. Reference numeral 111 denotes a driver for driving the heat generating portion 52 of the recording head 9 in accordance with the recording information signal. Reference numeral 124 denotes a power supply unit that supplies power to each of the above units, and includes an AC adapter and a battery as a drive power supply device. Reference numeral 391 denotes a ROM provided in each ink tank 39 mounted on the printer, and this ROM stores information on the type including the color of ink stored in the tank. The MPU 102 reads out this information and uses it for the control of the printer, such as referring to a table described later in FIG. 12 according to the ink type in the preliminary ejection control described later in FIG.

  In the recording system including the printer and the host computer 100 that supplies the recording information signal to the printer, when the recording data is transmitted from the host computer 100 via a parallel port, an infrared port, a network, or the like, it is required at the head portion The command is added. The commands include, for example, the type of recording medium on which recording is performed (the type of plain paper, OHP sheet, glossy paper, etc., and the type of special recording medium such as transfer film, cardboard, banner paper, etc.), medium size ( A0, A1, A2, etc.), recording quality (draft, high quality, medium quality, specific color emphasis, monochrome / color type, etc.), paper feed path (type and type of recording medium feeding means provided in the printer) For example, ASF, manual feed, paper feed cassette 1, paper feed cassette 2, etc.) and whether or not an object is automatically identified. In addition, when a configuration for applying a treatment liquid for improving the fixability of ink on a recording medium is employed, information for determining the presence or absence of the application may be transmitted as a command.

  In accordance with these commands, the printer reads data necessary for recording from the ROM 105 described above, and performs recording based on these data. The data includes, for example, data for determining the number of printing passes when performing the above-described multi-pass printing, the ink ejection amount per printing medium unit area, the printing direction, and the like. In addition, the type of data thinning mask applied when performing multi-pass printing, the driving conditions of the recording head (for example, the shape of the driving pulse applied to the heat generating portion 52, the application time, etc.), the dot size, and the recording medium There are also conveyance conditions, carriage speed, and the like.

  FIG. 3 is a diagram illustrating a configuration example of an ink supply system to the recording head. There are mainly two methods for supplying ink to the recording head. One is to mount an ink tank for holding ink on the carriage and to supply ink directly to the recording head. The other is to supply ink by connecting a tube called a supply tube between an ink tank arranged at a fixed portion of the apparatus and a recording head mounted on a carriage. So this method is adopted.

  As described above, the ink tanks 39Bk, 39Lc, 39C, 39Lm, 39M, and 39Y include black (Bk), light cyan (Lc), cyan (C), light magenta (Lm), magenta (M), and yellow (Y). Of ink is stored. Similarly, as described above, there are two types of ink tanks 39Bk corresponding to the inks Bk1 and Bk2, and these are used interchangeably. Which of these two types of ink tanks is installed can be known by reading the contents of the ROM 391 provided in each tank as described above.

  Reference numeral 45 denotes an ink supply tube connected to each color ink tank, which has flexibility to follow the movement (scanning) of the carriage 701 or the recording head 9. Reference numeral 46 denotes a joint mounted on the carriage unit 2 together with the recording head. The other end of each supply tube 45 is connected, and has an ink outlet tube 45A coupled to the ink introduction portion 23 of the recording head 9 (the connection portion). Is omitted).

  Each ink tank is molded by resin such as PP or PE by injection blow or the like, and is assembled using techniques such as ultrasonic welding, thermal welding, adhesion, and fitting. In FIG. 3, the tank exterior is illustrated as a type that functions as an ink chamber as it is, and the joint rubber 44 is disposed at the bottom thereof, while the hollow needle 43 provided at the end of the supply tube 45 penetrates the joint rubber 44. The ink supply is received by entering the ink chamber. For each ink tank, a buffer chamber 41 is disposed in the same connection form via a hollow needle 42. This fulfills the function of absorbing a change in pressure in the ink chamber due to an environmental change or the like so as not to affect the supply tube 45 and thus the recording head 9 side. For example, when the air inside the ink tank expands, the ink that overflows from the inside of the tank is temporarily held, and when the air inside the ink tank contracts, the retained ink is returned to the ink tank. Have.

  Note that the configuration of the ink tank is not limited to the above-described one. For example, the ink tank has an ink bag filled with ink, and the inside is filled with a porous material so as to be impregnated and retained, and the ink discharge of the recording head is performed. A negative pressure for holding the ink meniscus formed at the outlet may be generated. Further, as a form of the tank having such a negative pressure generating mechanism, a flexible bag for storing ink is provided, and the inner volume of the bag is expanded by a spring mechanism or the like provided inside or outside the bag. It may be one that is energized.

  FIG. 4 is a schematic perspective view showing a configuration example of the recovery unit. The two caps 27 are supported by an elevating mechanism (not shown) so as to be movable up and down, and in the raised position, the face surface on which the six color ejection portions of the recording head are arranged is capped by three colors. As a result, it is possible to perform protection during non-recording operation or to perform suction recovery. During the recording operation, it is set at a lowered position that avoids interference with the recording head 9, and can receive preliminary ejection by facing the face surface.

  Wiper blades 21 and 22 made of an elastic member such as rubber are fixed to the wiper holder 23. The wiper holder 23 is movable along the guide 24 in the front-rear direction of the drawing indicated by the arrow W (the direction in which the discharge ports are arranged in the discharge unit). When the recording head 9 reaches the home position, the wiper holder 23 moves in the direction of arrow W, so that wiping is possible. When the wiping operation is completed, the carriage is retracted out of the wiping area and then returned to a position where the wiper does not interfere with the face surface or the like. In this example, two wiper blades 21 for wiping the face surface of the three discharge units and a wiper blade 22 for wiping the entire surface of the recording head 9 including the discharge surfaces of the discharge units 11 to 16 are provided. Yes.

  The suction pump 29 joins the cap 27 to the face surface and generates a negative pressure in a state where a sealed space is formed therein, so that the ink is filled from the ink tank into the recording head or the discharge unit, or the discharge port or It is possible to suck and remove dust, fixed matter, bubbles, etc. existing in the inner ink path. In the illustrated example, a suction pump 29 in the form of a tube pump is used, which includes a member formed with a curved surface for holding (at least a part of) a tube 28 having flexibility, and a member It is possible to have a roller capable of pressing the flexible tube toward the surface and a roller support portion that can rotate while supporting the roller. That is, by rotating the roller support portion in a predetermined direction, the roller rolls while crushing the flexible tube on the curved surface forming member. Along with this, negative pressure is generated in the sealed space formed by the cap 7 and the ink is sucked from the discharge port and drawn from the cap 27 to the tube or the suction pump, while the drawn ink further includes an appropriate member (waste ink). It is transferred toward the absorber.

  Further, the recovery unit of the present embodiment is provided with a preliminary discharge receiver (not shown in FIG. 4) described later in FIG. 10 at a position along the arrangement direction of the two caps 27.

  FIG. 5 is a schematic perspective view showing the recording head mounted on the carriage 701 of the printer from the direction in which ink is ejected. Here, as described above, the recording head 9 includes inks of different tones (including color and density) in the main scanning direction S, black (Bk), light cyan (Lc), cyan (C), and light magenta (Lm). ), Magenta (M) and yellow (Y) inks can be ejected. Ink is supplied from the ink introduction unit 23 to each ejection unit via an ink flow path inside the recording head. Ink is introduced into the ink introduction part 23 from a later-described ink tank through a tube.

  FIG. 6 is a schematic perspective view showing one of the ink discharge portions for the six colors.

  Each ejection unit uses, for example, thermal energy that causes film boiling in the ink in response to energization as energy used for ejecting the ink, and heat generated by the heating unit 52 formed at a predetermined pitch. It has a substrate 51 in which two rows are arranged in parallel. An ink supply port 56 that communicates with the ink flow path is provided between the heating unit rows of the substrate 51. For the substrate 51, a member (orifice plate) 54 in which a nozzle 55 corresponding to the heat generating portion 52 and an ink path 59 for supplying ink from the ink supply port 56 corresponding to each of the nozzles 55 are formed. Are joined to form a discharge section.

  In each row, the heat generating portion 52 and the nozzles (ejection ports) 55 are arranged so as to be shifted by a half pitch, thereby realizing a desired recording resolution. Here, the same recording density and the same number of nozzles may be used for each of the ejection units 11 to 16, or different recording densities and the number of nozzles may be used. In this embodiment, 640 nozzles are arranged at a density of about 245 nozzles per cm in the Bk ejection unit 11, and the density of about 490 nozzles per cm for each color in the other color ink ejection units 11-15. 1280 nozzles are arranged.

  In this example, the heating unit 52 uses a discharge unit that discharges ink in a direction perpendicular to the substrate 51. However, a discharge unit that discharges ink in a parallel direction may be used.

  7, 8 and 9 are flowcharts showing the recovery process performed by the recovery unit during recording and after the end of recording, except during recording, respectively, according to one embodiment of the present invention.

  In the recovery process other than during recording shown in FIG. 7, first, if there is a soft-on (secondary power-on) or recording start command at Step 1 (hereinafter abbreviated as S1, and other steps are also the same), this process is performed. It is activated. Then, the current time is read in S2, the previous time when the recording head was cleaned is read in S3, and the cleaning interval is calculated in S4. This “cleaning” is an aspect of the recovery process, and performs all of suction recovery, preliminary discharge, and wiping by a predetermined amount.

  In S5, it is determined whether or not the cleaning interval calculated in S4 exceeds a predetermined threshold value. If the cleaning interval exceeds the predetermined threshold value, cleaning is executed in S6. In S7, the previous cleaning time Tb is replaced with the current time Ta, and the READY state (S8) is set.

  Next, in the recovery process during recording shown in FIG. 8, it is first determined whether or not the recording head is capped to make the recording head in a recordable state (S9). This can be confirmed by a signal from the capping sensor. If it is capped, the cap is opened (S10). Next, in S11, the recovery sequence other than during recording described in FIG. 7 is performed.

  When this recovery sequence is completed, paper feed is performed (S12), and when it is determined that the print data for one scan of the print head is available in the print buffer 121 (S13), preliminary ejection before the start of printing is performed (S14). A printing operation for one scan is performed (S15). Next, it is determined whether or not the discharge is due to the end of recording or forced discharge (S16). If it is not paper discharge, the elapsed time Tc from the cap opening in S10 is read (S17), and it is determined whether this time Tc exceeds the time Tcap to be capped (S18). If the time Tcap is exceeded, it is next determined whether or not the elapsed time Tc in the cap open state exceeds the time Tpreinj to be pre-discharged (S20). If this time has not been exceeded, the process returns to S13, and the printing operation for the next scan is performed thereafter.

  If it is determined in S18 that the time Tcap has been exceeded, the recording head is capped (S19), and the process returns to S13. As a result, it is possible to cope with a situation in which the recording data is not sent from the host device for a relatively long time, and to capping the recording head to suppress the thickening of the ink in the recording head. When this capping is performed, an operation of opening the cap is performed immediately before the preliminary discharge in S14. When it is determined that the elapsed time Tc exceeds the time Tpreinj, wiping and preliminary discharge are performed (S21). Thereby, for example, preliminary ejection is performed every several scans of the recording head, and partial thickening at each ejection port during the recording operation can be suppressed. If it is determined that the recording is finished by the paper discharge command (S16), the paper is discharged (S22), and the recording operation is finished.

  In the above-described embodiment, preliminary ejection is performed immediately before scanning. However, it is possible to select whether to perform preliminary ejection immediately before printing according to the time of a timer.

  The recovery process after the recording operation shown in FIG. 9 is started when the recording sequence for one page (S23) described in FIG. 8 is completed. First, in S24, it is determined whether or not the recording dot number N exceeds the prescribed dot number N1. When the threshold value N1 is exceeded, wiping is performed (S25). Thus, particularly when the recording amount is large and there is a high possibility that a large amount of ink droplets or the like is attached to the face surface of the recording head, this can be removed. Next, in S26, it is determined whether or not there is recording data for the next page. If there is recording data for the next page, the recording sequence of S23 is repeated. If there is no next page recording data, it waits for 55 seconds (S27). If there is no input of recording data for the next page during this waiting time, wiping is performed (S28), then capping is performed (S29), and this process ends.

  Note that the dot count for wiping execution determination is used by storing the number of dots counted by the dot counter in the printer in the memory 122 or the like. In this embodiment, the determination of whether or not to perform wiping is performed at the end of each page. However, in the case of a plotter or large format printer with a large recording area, which is the object of this embodiment, wiping is performed after each recording scan. It is also possible to configure so as to determine whether or not. In addition, the ink mist adhering to the face as well as the dot count may vary depending on the recording duty, so the number of dots should be increased or decreased by adding a coefficient calculated based on the duty to the number of dots. You can also.

  FIG. 10 is a schematic cross-sectional view showing a preliminary discharge receiver according to an embodiment of the present invention.

  As described above, the preliminary discharge receiver 62 is provided in a part of the moving range of the recording head 9 as a part of the recovery unit. Preliminary ejection is performed as part of the recovery outside recording and recovery during recording described with reference to FIGS. 7 and 8. These preliminary ejections are performed by the recording head 9 moving to the preliminary ejection receptacle 62.

  In the preliminary ejection of this embodiment, the recording head 9 is stopped at the position shown in the figure, and ejection is first performed from the Bk ejection section 11 and then ejection from the Lc ejection section 12. Preliminary discharge is sequentially performed from the discharge unit. In addition, it can also be set as the structure which discharges all Bk discharge part 11, Lc discharge part 12, C discharge part 13, Lm discharge part 14, M discharge part 15, and Y discharge part 16 simultaneously. In addition, the Bk discharge unit 11, the Lc discharge unit 12, and the C discharge unit 13 are discharged simultaneously, and then the Lm discharge unit 14, the M discharge unit 15, and the Y discharge unit 16 are discharged simultaneously. It is also possible to adopt a three-divided configuration in which these ejection portions are ejected every two arbitrary heads. Since the preliminary ejection receiver shown in FIG. 10 according to the present embodiment has a width corresponding to the width of the recording head 9, it can cope with simultaneous or sequential preliminary ejection. In the case where a sufficiently wide preliminary discharge port is not provided, a preliminary discharge receptacle having a width of one to several discharge portions may be provided to perform preliminary discharge sequentially as described above. It is also possible to perform ejection sequentially from the respective color ejection sections or recording heads while moving the recording head so that the ejected inks land on the same position on the preliminary ejection receptacle. This makes it possible to efficiently mix different inks described below.

  As shown in FIG. 10, the ink droplets 61 ejected from the ejection units land on the preliminary ejection receiver 62 and travel along (flow through) the members forming the preliminary ejection receiver 62, and the ink waste liquid that is an aggregate of ink 65 is formed. The ink waste liquid 65 is further guided to the ink discharge port 64 through the ink flow path 63 connected to the lower portion of the preliminary discharge port. The ink guided to the ink discharge port 64 is guided to the waste ink absorber 66 housed in the waste ink case 67. As the waste ink absorber 66, generally, a foam of a resin such as polyurethane or melamine, a nonwoven fabric using fibers such as pulp, rayon, or polyester, a needle felt using these, or the like is used. Further, it may be collected in a waste ink collecting bottle or the like. In order to control the flow of ink in the absorber, a diffusion groove 68 is provided for the purpose of preventing overflow when a large amount of waste ink is generated by various replacement operations or for temporarily storing ink and promoting diffusion. It is done. Also in this embodiment, the groove 68 is provided so that highly viscous ink can temporarily stay. In the example shown in FIG. 10, the ink waste liquid 65 guided into the waste ink case 67 falls into the diffusion groove 68 and then diffuses.

  By the way, as described above, it is possible to make various inks even if they are inks of the same color depending on penetrability or non-penetration, pigment or dye, ink concentration, solvent composition and the like. For example, in order to obtain a relatively high density with a small amount of ink, it is only necessary to increase the density of the contained color material. On the other hand, it has been known that problems occur in reliability, stability during storage, and the like. In addition, the pigment ink can obtain a sufficient concentration. On the other hand, when recording is performed on a glossy recording medium, the glossiness of the recorded portion is lost and the quality of the recorded matter may be deteriorated. Further, it is known that a dye-based ink can obtain a relatively good image when recorded on a glossy recording medium, but a sufficient density cannot be obtained with plain paper or coated paper. This is because the pigment remains on the surface, which is advantageous in terms of concentration, but the gloss has a characteristic that the gloss is lowered because it remains on the surface. In this way, inks may have different properties even with the same color (for example, Bk).

  In the present embodiment, as described above, the black inks Bk1 and Bk2 having different characteristics such as the degree of thickening are selectively used by exchanging their ink tanks. Accordingly, it is possible to always record a high-quality image using a black ink of a type corresponding to the type of image to be recorded and the type of recording medium to be used.

  As described above, in the preliminary ejection receiver, the degree of thickening after ejection is different depending on the type of ink, so that accumulation occurs in the inclined portion of the preliminary ejection receiver 62 or stays in the middle of the ink flow path 63. May occur, and the recovery of the ink waste liquid 65 may be hindered. Moreover, it may accumulate on a waste ink absorber and may prevent further ink from being absorbed.

  On the other hand, according to one embodiment of the present invention, during preliminary ejection, ink having a high degree of thickening is simultaneously ejected with other ink that does not easily increase in viscosity, and these inks are mixed and mixed. To reduce the viscosity.

  FIG. 11 is a diagram illustrating changes in viscosity of inks Bk1, Bk2 and ink Bk1 according to an embodiment of the present invention mixed with other inks with a low degree of thickening. In the figure, the horizontal axis indicates the ratio of the ink amount that changes due to evaporation to the amount at the start of evaporation, and the vertical axis indicates the viscosity.

  In the figure, 69 indicates a viscosity change curve of the ink Bk1, and 70 indicates a viscosity change curve of the ink Bk2. As shown by these curves, there is not much difference in viscosity change for both inks up to a remaining amount of about 50%. However, the viscosity of the ink Bk1 starts to rapidly increase when the remaining amount falls below 50%, and a large difference in viscosity from the ink Bk2 occurs around 30% (70% evaporation), which is almost the limit. . The viscosity of the ink Bk1 exceeds the flow limit 72 (about 2000 mPa · s) around the remaining amount of 30%. Beyond this limit, the ink can hardly flow.

  On the other hand, 71 indicates a viscosity change curve of the ink Bk1 mixed with another predetermined ink having a lower degree of thickening. As shown in the graph, the mixture of the ink Bk1 and the other ink tons can suppress a sudden increase in viscosity, and can prevent the flow limit 72 from being exceeded even in the vicinity of 30% of the ink remaining amount near the limit. As described above, in one embodiment of the present invention, the ink having a high degree of thickening and the ink having a lower viscosity are mixed at the time of preliminary ejection to prevent the thickening exceeding the flow limit. It is. That is, an ink with a low degree of thickening is ejected and mixed in a sufficient amount so that an ink with a high degree of thickening does not exceed the flow limit. Such ink mixing can be realized by ejecting ink having a high degree of thickening and ink having a lower viscosity to the preliminary ejection receptacle 62. In this case, as described above, it is not always necessary that these inks be ejected to the same location of the preliminary ejection receptacle and mixed there, but after the ink is ejected to the preliminary ejection receptacle, the ink moves (flows). Of course, it may be mixed.

  FIG. 12 is a diagram showing a table for determining the number of preliminary ejections used in the preliminary ejection control according to an embodiment of the present invention, and FIG. 13 is a diagram showing a conventional similar table for comparison. is there.

  In FIG. 12, preliminary discharges A1, A2, A3, B, C, and D are performed as part of the recovery process described above with reference to FIGS. Specifically, the preliminary ejections A, B, and C are performed by “cleaning” in step S6 of the non-recording recovery process at the time of non-recording shown in FIG. 7, and the specified time U used in the process of FIG. 7 is 60 minutes. Hereinafter, one of the preliminary ejection tables A, B, and C is referred to in “cleaning” depending on which of 240 minutes or less or 720 minutes or less is set. The preliminary ejections B, C, and D are respectively performed in steps S14, S21, and S11 of the recovery process during recording shown in FIG.

  As shown in FIG. 12, for example, in the case of using the ink Bk1 in the “preliminary ejection A1” (hereinafter, the preliminary ejection in this case is also referred to as “preliminary ejection mode Bk1”), the preliminary ejection of the recording head of the ink Bk1 is performed. The number of discharges is 200. This is because the ink Bk1 is easy to thicken, so that the number of ejections is increased and the removal of the thickened ink by the preliminary ejection is ensured. In this preliminary ejection mode Bk1, preliminary ejection (hereinafter referred to as “color ink”) of other inks C, Lc, M, Lm, and Y (hereinafter collectively referred to as “color ink”) is performed. The number of discharges in “preliminary discharge mode Color1”) is 400. Accordingly, when the preliminary discharge A1 is performed and the ink Bk1 and the color ink are discharged and mixed in the preliminary discharge receiver 62, the mixture can be prevented from exceeding the flow limit described with reference to FIG. . That is, the number of ejections: 400 in the preliminary ejection mode Color1 is set as an amount that does not exceed the flow limit even when mixed with the amount of ink Bk1 in the number of ejections: 200 in the preliminary ejection mode Bk1. As a result, it is possible to prevent the accumulation of ink having a high viscosity at the time of evaporation in the preliminary discharge receiver.

  When the ink Bk2 is used in the “preliminary ejection A1”, the number of preliminary ejections of the recording head of the ink Bk2 is 40. This is because the ink Bk2 has a lower degree of thickening than the ink Bk1, and thus the number of ejections does not have to be so large. When this ink Bk2 is used (hereinafter, preliminary ejection in this case is also referred to as “preliminary ejection mode Bk2”), preliminary ejection of color ink (hereinafter, preliminary ejection in this case is also referred to as “preliminary ejection mode Color2”). The same number of discharges is 40. Similarly, since each of the color inks has a lower degree of thickening than the ink Bk1, it is not necessary to increase the number of ejections, and the ink Bk2 originally does not exceed the flow limit. This is because it is not necessary to consider the fluidity of the mixture with Bk2.

  On the other hand, in the conventional example shown in FIG. 13 for comparison, the same “preliminary ejection A1” and the same number of color ink ejections are 40 in both the preliminary ejection mode Bk1 and the preliminary ejection mode Bk2. For this reason, when the ink Bk1 is used, even if this ink is mixed with the color ink, the viscosity change of the mixture cannot be suppressed and the flow limit may be exceeded, and as a result, deposits are generated in the preliminary discharge receiver. There is.

  In FIG. 12, for the other preliminary ejections A2 to D, the number of ejections in the preliminary ejection mode Color1 is set in particular so that the mixture of the ink Bk1 and the color ink does not exceed the flow limit. Needless to say, the number of discharges in the preliminary discharge mode Color1 is determined in consideration of various other factors. However, even in that case, it is obvious that the number of ejections in the preliminary ejection mode Bk1 needs to be set so that at least the mixture does not exceed the flow limit when mixed with the ink Bk1.

(Embodiment 2)
FIG. 14 is a view showing a table used in the preliminary discharge control according to another embodiment of the present invention, and is the same view as the view shown in FIG.

  In the first embodiment, the number of ejections is the same between the color inks in both the preliminary ejection mode Color1 and the preliminary ejection mode Color2. On the other hand, in the present embodiment, the number of ejections is made different between the color inks in each mode. In other words, the number of ejections is increased for inks that tend to improve fluidity, generally, inks with a low degree of thickening. For example, in the “preliminary ejection A1”, the number of inks Lc and Lm in the preliminary ejection mode Color1 corresponding to the preliminary ejection mode Bk1 when using the ink Bk1 is 400, and the number of ejections of the inks C, M, and Y is respectively 100. This is because the inks Lm and Lc have a lower pigment concentration than the inks C, M, and Y, and the degree of thickening is low, so that they are mixed more than M, C, and Y. Assuming that the inks of the first embodiment and the present embodiment have the same composition, as can be seen from the comparison with the table shown in FIG. 12, the increase in the viscosity of the mixture of the ink Bk1 and the color ink is suppressed to flow. As shown in FIG. 12, it can be seen that the discharge amount necessary for not exceeding the limit does not have to be 400 for all color inks.

  As described above, according to the present embodiment, the number of ejections to be ejected by the preliminary ejection can be reduced as much as possible, and the accumulation of ink having a high viscosity at the time of evaporation can be prevented more effectively in the preliminary ejection receiver.

(Other embodiments)
As described in Embodiment 2 above, the number of ejections may be different among the color inks depending on the degree of increase in the viscosity of each of the color inks C, Lc, M, Lm, and Y. As an example, For example, in any of the preliminary ejection mode Color1 and the preliminary ejection mode Color2 corresponding to the preliminary ejection mode Bk1 and the preliminary ejection mode Bk1, the number of Y ejections may be constant and the other color inks may be changed.

(Still another embodiment)
In each of the above embodiments, the Bk ink is exchanged and used. For example, the ink Bk1 and the ink Bk2 may include a plurality of recording heads and ink tanks, and may be used properly according to the mode. Of course, the preliminary discharge of each of the above-described embodiments according to the present invention can also be executed.

  Further, the ink whose viscosity is likely to increase is not limited to the black ink described in each of the above embodiments, and it is of course possible to set an ink to be diluted with an ink having a lower degree of thickening depending on the degree of thickening. It is. Further, as such an object, it is not necessary for the ink to exceed the flow limit described in FIG. 11 alone, and the ink having the highest degree of thickening among the ink groups to be used is to be diluted. be able to. According to this, it is possible to obtain the effect of increasing the fluidity in the preliminary discharge receiver.

1 is a perspective view showing an ink jet printer according to an embodiment of the present invention. FIG. 2 is a block diagram mainly showing a control configuration of the printer shown in FIG. 1. FIG. 2 is a diagram illustrating a configuration example of an ink supply system to a recording head used in the printer illustrated in FIG. 1. It is a typical perspective view which shows the structural example of the recovery unit used with the printer shown in FIG. FIG. 2 is a schematic perspective view showing a recording head mounted on a carriage of the printer shown in FIG. 1 from a direction in which ink is ejected. FIG. 2 is a schematic perspective view illustrating one of six color ink ejection portions of the recording head. It is a flowchart which shows the recovery process performed by the recovery unit other than recording based on one Embodiment of this invention. 6 is a flowchart illustrating a recovery process performed by a recovery unit during recording according to an embodiment of the present invention. It is a flowchart which shows the recovery process performed by the recovery unit after completion | finish of recording based on one Embodiment of this invention. It is typical sectional drawing which shows the preliminary discharge receptacle which concerns on one Embodiment of this invention. It is a figure explaining the viscosity change of what mixed ink Bk1 and Bk2 which concern on one Embodiment of this invention, and the ink Bk1 with the ink with the other low degree of thickening. It is a figure which shows the table for determining the discharge number of the preliminary discharge used by the preliminary discharge control which concerns on one Embodiment of this invention. It is a figure which shows the conventional similar table for a comparison. It is a figure which shows the table for determining the discharge number of the preliminary discharge used by the preliminary discharge control which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Recording head 11 Black discharge part 12 Light cyan discharge part 13 Cyan discharge part 14 Light magenta discharge part 15 Magenta discharge part 16 Yellow discharge part 39 Ink tank 61 Ink droplet 62 Preliminary discharge receptacle 63 Ink flow path 64 Ink discharge port 65 Ink waste liquid 66 Waste ink absorber 67 Waste ink case 68 Diffusion groove 100 Host 101 PPI
102 MPU
103 RAM
104 ROM

Claims (12)

An inkjet recording apparatus that performs recording using a recording head that discharges a plurality of types of ink having different degrees of thickening,
A preliminary discharge receptacle;
A means for performing preliminary ejection by ejecting the plurality of types of ink from the recording head to the preliminary ejection receiver, and among the plurality of types of ink, the number of ejections of the first ink having a higher degree of viscosity increase On the other hand, a preliminary ejection means for ejecting the first ink and the second ink by increasing the ejection number of the second ink having a lower degree of thickening than the first ink,
An ink jet recording apparatus comprising:   2. The ink jet recording according to claim 1, wherein the number of ejections of the second ink is determined so that a mixture when the first and second inks are mixed in the preliminary ejection receptacle does not exceed a flow limit. apparatus.   3. The inkjet according to claim 1, wherein the first ink and the second ink have a viscosity of 2000 mPa · s or more and 2000 mPa · s or less, respectively, when an ink remaining amount by evaporation is 30%. Recording device. An inkjet recording apparatus that performs recording using a recording head that discharges a plurality of types of ink having different degrees of thickening,
A preliminary discharge receptacle;
A means for performing preliminary ejection by ejecting the plurality of types of ink from the recording head to the preliminary ejection receiver, wherein the first color has a higher degree of viscosity than the first color among the plurality of types of ink. A first preliminary ejection mode for ejecting a third ink of a second color having a lower degree of thickening than the first ink of the first color for the first ink of a color and a second color different from the first color; Executing a second preliminary ejection mode in which the second ink of the first color and the third ink of the second color having a lower degree of viscosity than the first ink of the first color are ejected, and the first ink of the first color The number of ejections of the first ink is greater than the number of ejections of the second ink of the first color, and the number of ejections of the third ink of the second color is greater than the number of ejections of the first ink of the first color. Preliminary discharge means for executing the discharge mode or the second preliminary discharge mode;
An ink jet recording apparatus comprising:   The first and second inks of the first color are black inks, the third ink of the second color is cyan, light cyan ink having a lower color material density than the cyan ink, magenta, and color material density than the magenta ink. The ink-jet recording apparatus according to claim 4, wherein the ink-jet recording apparatus is a color ink containing light magenta ink and yellow having a low density.   The first and second inks of the first color are black inks, the third ink of the second color is cyan, a light cyan ink having a lower color material density than the cyan ink, 5. The ink jet recording apparatus according to claim 4, wherein the ink is light cyan and light magenta ink among magenta, light magenta ink having a color material density lower than that of the magenta ink, and color ink including yellow. A preliminary ejection method in an inkjet recording apparatus that performs recording using a recording head that ejects a plurality of types of inks having different degrees of thickening,
Preparing a preliminary discharge receptacle;
A step of performing preliminary ejection by ejecting the plurality of types of ink from the recording head to the preliminary ejection receiver, and among the plurality of types of ink, the number of ejections of the first ink having a higher degree of viscosity increase On the other hand, a preliminary ejection step of ejecting the first ink and the second ink by increasing the number of ejections of the second ink having a lower degree of thickening than the first ink,
A preliminary discharge method characterized by comprising:   8. The preliminary ejection according to claim 7, wherein the number of ejections of the second ink is determined so that the mixture when the first and second inks are mixed in the preliminary ejection receptacle does not exceed a flow limit. Method.   The preliminary ink according to claim 7 or 8, wherein the first ink and the second ink have a viscosity of 2000 mPa · s or more and 2000 mPa · s or less, respectively, when an ink remaining amount by evaporation is 30%. Discharge method. A preliminary ejection method in an inkjet recording apparatus that performs recording using a recording head that ejects a plurality of types of inks having different degrees of thickening,
Preparing a preliminary discharge receptacle;
The step of discharging the plurality of types of ink from the recording head to the preliminary discharge receiver to perform preliminary discharge, and among the plurality of types of ink, the first color having a higher degree of thickening than the first color. A first preliminary ejection mode for ejecting a third ink of a second color having a lower degree of thickening than the first ink of the first color for the first ink of a color and a second color different from the first color; Executing a second preliminary ejection mode in which the second ink of the first color and the third ink of the second color having a lower degree of viscosity than the first ink of the first color are ejected, and the first ink of the first color The number of ejections of the first ink is greater than the number of ejections of the second ink of the first color, and the number of ejections of the third ink of the second color is greater than the number of ejections of the first ink of the first color. A preliminary discharge step for executing the discharge mode or the second preliminary discharge mode;
A preliminary discharge method characterized by comprising:   The first and second inks of the first color are black inks, the third ink of the second color is cyan, light cyan ink having a lower color material density than the cyan ink, magenta, and color material density than the magenta ink. The preliminary ejection method according to claim 10, wherein the preliminary ejection method is a color ink containing low magenta light magenta ink and yellow. The first and second inks of the first color are black inks, the third ink of the second color is cyan, a light cyan ink having a lower colorant density than the cyan ink, constituting the plurality of inks, 11. The preliminary ejection method according to claim 10, wherein the ink is light cyan and light magenta ink among magenta, light magenta ink having a color material density lower than that of the magenta ink, and color ink including yellow.

Images