JP2011056685A - Ink jet recorder and recovery method of recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely discharge a mixed color ink in a recording head generated after the wiping of an ejection opening surface by a wiper blade in an ink jet recorder, and to suppress the useless consumption of an ink caused by excessive spare ejection. <P>SOLUTION: The ink adhered to the ejection opening surface where an ejection opening of the recording head is formed is wiped by the wiper blade (S102). After wiping by the wiper blade, ink droplets not contributing to recording are ejected (sparely ejected) (S105). The number of ink droplets ejected in spare ejection is set to be increased as the wiping performance of the wiper blade is deteriorated (S104). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus including a wiper blade that performs recording by ejecting ink from nozzles of a recording head and wipes ink adhering to the ejection port surface where the ejection ports of the nozzles of the recording head are formed. The present invention relates to a head recovery method.

  In an ink jet recording apparatus, clogging due to thickening and solidification of ink in the nozzles of the recording head and color mixing of inks due to entering different colors of ink into the nozzles cause deterioration in the quality of recorded images. For this reason, in order to keep the ink in the nozzles of the recording head in an appropriate state, a recovery process for recovering the ejection performance of the recording head is performed.

  Currently, when the nozzles of the recording head are extremely clogged, a recovery process called “suction recovery” is performed in which the suction force of the pump is used to forcibly suck and discharge ink from the nozzle discharge port. Has been. According to this suction recovery process, most clogging can be eliminated, and bubbles and the like existing inside the recording head can be discharged. For this reason, it is possible to restore the nozzle in which the ejection failure has occurred to normal ejection performance. However, if a large amount of ink adheres to the surface of the recording head after the suction recovery process is performed and the ink thickens or solidifies on the ejection port surface, the ink droplets displaced from the ejection port are displaced in the ejection direction. May occur. Also, different color inks adhering to the ejection port surface may be drawn into the interior by the negative pressure in the nozzles, resulting in color mixing. Such misalignment in the ejection direction of ink droplets and color mixing in the nozzle significantly reduce the quality of the recorded image. Therefore, it is necessary to remove the ink adhering to the ejection port surface by the suction recovery process.

  Therefore, a recovery process called “wiping” is performed in which the surface of the recording head is wiped with a wiper blade made of a rubber member such as urethane. According to this process, the ink attached to the surface of the recording head by the suction recovery process can be wiped off. For this reason, it is possible to reduce the ink being drawn into the inside due to the increase in the viscosity of the ink adhering to the ejection port surface, the deviation in the ejection direction of the ink droplets due to solidification, the negative pressure in the nozzle, or the like. However, even with this wiping, when wiping off the adhering ink, there is a possibility that the wiper blade pushes different colors of ink into the nozzles to cause color mixing. In addition, when the amount of ink adhering to the ejection port surface by the wiper blade is large, the adhering ink cannot be sufficiently wiped off, the ink remains on the ejection port surface of the recording head, and the ink is drawn into the nozzle. May cause color mixing.

  On the other hand, in Patent Document 1, it is possible to suppress deterioration in image quality by performing so-called “preliminary discharge”, which discharges ink droplets that do not contribute to recording after wiping, and discharges mixed color ink from nozzles. It is disclosed.

JP 61-230950 A

  However, in Patent Document 1, as the usage period of the recording apparatus becomes longer, there arises a problem that the mixed color ink in the nozzle cannot be sufficiently discharged by the preliminary discharge. This is due to the fact that the wiping performance of the wiper blade decreases as the recording apparatus is used for a longer period of time. That is, the wiper blade is generally composed of a rubber member, and when the ink is wiped by wiping, the wiper blade absorbs and swells the ink, and the absorbed ink is dried and contracted repeatedly. Wear due to contact with the discharge port surface. By repeating such deformation and wear for each wiping, the wiper blade gradually deteriorates. For this reason, the amount of ink remaining on the ejection port surface of the recording head after wiping increases as the wiper blade deteriorates, and the amount of ink drawn into the nozzles increases as the remaining ink amount increases. However, in Patent Document 1, since a predetermined number of preliminary ejections are always performed after wiping, in a situation where deterioration of the wiper blade progresses and the mixed color ink in the nozzle increases, the mixed color ink is not removed even if the preliminary ejection is performed. It cannot be completely removed and a sufficient recovery effect cannot be expected.

  The present invention can reliably discharge the mixed color ink generated in the nozzles of the recording head by preliminary discharge after wiping the discharge port surface by the wiper blade, and can suppress wasteful consumption of ink by excessive preliminary discharge. An object is to provide an ink jet recording apparatus.

In order to achieve the above object, the present invention comprises the following arrangement.
According to a first aspect of the present invention, in an ink jet recording apparatus that performs recording using a recording head having a nozzle capable of ejecting ink, the ink attached to the ejection port surface of the recording head where the ejection port of the nozzle is formed A wiper blade for wiping the discharge port surface, preliminary wiping means for discharging ink droplets that do not contribute to recording from the discharge port after wiping the discharge port surface by the wiper blade, and wiping the wiper blade to the discharge port surface Determination means for determining performance, and control means for controlling to increase the number of ink droplets ejected by the preliminary ejection means as the wiping performance of the wiper blade determined by the determination means decreases.

  According to a second aspect of the present invention, in an ink jet recording apparatus that performs recording using a recording head having nozzles capable of ejecting ink, the discharge port surface of the recording head on which the nozzle discharge port is formed is a wiper blade. A method for recovering a recording head to be wiped, wherein after the discharge port surface is wiped by the wiper blade, a preliminary discharge step of discharging ink droplets that do not contribute to recording from the discharge port; A determination step of determining the wiping performance of the wiper blade, and a control step of controlling to increase the number of ink droplets ejected by the preliminary ejection means as the wiping performance of the wiper blade determined in the determination step decreases. It is characterized by providing.

  According to the present invention, the number of preliminary ejections performed after wiping the wiper blade is optimized according to the deterioration of the wiper blade. For this reason, it is possible to reliably discharge the mixed color ink existing in the nozzles of the recording head, and it is possible to reduce wasteful consumption of ink due to excessive preliminary ejection.

1 is a schematic perspective view showing an internal configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention. FIG. 2 is an external perspective view of a recording head mounted on the recording apparatus illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the recording apparatus illustrated in FIG. 1. FIG. 4 is a diagram illustrating an internal structure of the recording head illustrated in FIG. 3. FIG. 2 is a perspective view showing a wiper of a wiping mechanism of the recording apparatus shown in FIG. 1. FIG. 2 is a perspective view schematically showing a recovery mechanism of the recording apparatus shown in FIG. 1. It is a perspective view which shows the state which the wiper blade of a wiping mechanism swells. It is a perspective view which shows the state which the wiper blade of a wiping mechanism contracts. It is a table which shows the relationship between the frequency | count of accumulation wiping of a wiper blade, and the number of preliminary ejections after wiping. 6 is a follow chart showing a recovery process sequence of the recording head performed by the control system in the first embodiment of the present invention. 10 is a follow chart illustrating a recovery process sequence of a recording head performed by a control system according to a second embodiment of the present invention. It is a flowchart which shows the correction process of the elapsed time shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, the overall configuration of the ink jet recording apparatus applied to the present embodiment will be described.
FIG. 1 is a schematic perspective view showing the internal configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention. An inkjet recording apparatus (hereinafter also simply referred to as a recording apparatus) 1 is a serial scan type recording apparatus that forms a color image. In this serial scan type recording apparatus, an operation of ejecting ink from the recording head while moving the carriage on which the recording head is mounted in the x direction (main scanning direction), and the y direction (sub scanning direction) intersecting the main scanning direction. And the operation of conveying the recording medium alternately. As a result, images are sequentially formed on the recording medium.

  Specifically, when an instruction to start recording is given, the paper feed motor 5 is first driven, and the paper feed roller 6 rotates via a gear (not shown). One recording medium is fed into the recording apparatus from the recording media such as recording sheets stacked on the sheet feeding tray 8 by the rotation of the sheet feeding roller 6. A carriage 2 equipped with a recording head for ejecting a plurality of colors of ink moves in the main scanning direction by driving a carriage motor 3. At this time, the recording head ejects ink at a predetermined timing according to the recording signal, and forms an image for one band on the recording medium. The image for one band refers to a band-like image that can be formed on a recording medium by one scan of the recording head, and its width is the length L (in the sub-scanning direction of the nozzle row formed on the recording head). This corresponds to FIG. Here, when an image for one band is formed, the recording medium is conveyed by a predetermined amount in the sub-scanning direction by a conveyance motor (not shown), and further, recording scanning is performed by the recording head.

  FIG. 2 is an external perspective view of the recording head mounted on the carriage. As shown in FIG. 2, orifice plates 11 a, 11 b, 11 c, 11 d, 11 e, and 11 f are arranged in parallel on the plurality of recording heads 9 mounted on the carriage 2. Each orifice plate has a plurality of ejection port arrays in which a plurality of ink ejection ports are arranged in a certain direction (y direction). In the example shown in FIG. 2, 15a is an ejection port array for ejecting dye black ink as the first ink, 15b is an ejection port array for ejecting pigment black ink as the second ink, and 15c is pigment black as the third ink. It is an ejection port array that ejects ink. 15d is an ejection port array for ejecting yellow ink, 15e is an ejection port array for ejecting magenta ink, and 15f is an ejection port array for ejecting cyan ink. The pigment black ink which is the second and third inks ejects the same ink from two different ejection port arrays for high speed and high definition. Hereinafter, the second and third inks are referred to as a first pigment black ink and a second pigment black ink, respectively. The configuration of the recording head 9 will be described in detail later with reference to FIGS.

  The description of the recording apparatus 1 will be continued with reference to FIG. In the present embodiment, the carriage belt 4 is used as means for transmitting a driving force from the carriage motor 3 to the carriage 2. However, other driving methods such as a lead screw may be used instead of the carriage belt 4. The recording medium fed into the recording apparatus passes between the paper feed roller 6 and the pressure roller 7 and is guided to a position where recording by the recording head 9 is possible.

  In FIG. 1, the position where the carriage 2 is located is the home position in the movement path of the carriage 2. When recording is not being performed, a capping mechanism (not shown) disposed below the home position seals (capping) the ejection port forming surface of the recording head 9. When recording is started, the capping mechanism opens the recording head 9, thereby enabling the carriage 2 to move in the main scanning direction.

  FIG. 3 is a block diagram showing a schematic configuration of a control system provided in the recording apparatus shown in FIG. In FIG. 3, a programmable peripheral interface (hereinafter referred to as PPI) 101 receives a command signal (command) and a recording information signal input from a host computer (not shown) and transfers them to the MPU 102. The PPI 101 controls the console 106 and receives a signal from the home position sensor 107 that detects whether the carriage 2 is at the home position.

  The MPU 102 executes various determination processes, counting processes such as the number of ink ejections and the number of wiping operations, and control of each unit in the apparatus according to a control program stored in the ROM 105. The RAM 103 is a memory that temporarily stores various data, and is used as a data storage area for storing received data and a work area for the MPU 102 to execute various processes. The ROM 104 stores pattern information such as characters and records corresponding to the code information for use in font generation, and outputs various pattern information corresponding to the input code information. The print buffer 121 has a capacity for a predetermined line in order to store data expanded by the ROM 104 or the like. The MPU 102 and the ROM constitute the control means and determination means in the present invention.

  Each block described above is controlled by the MPU 102 via the address bus 117 and the data bus 118. In FIG. 3, reference numeral 110 denotes a conveyance motor for conveying a recording medium such as a recording sheet in the sub-scanning direction, and reference numeral 113 denotes a capping motor that drives the capping mechanism 130. By driving the capping motor 113 and bringing the cap provided on the capping mechanism 130 into contact with the ejection port surface of the recording head to cover the ejection port, the ejection port of the recording head 9 can be blocked from the outside air, Thereby, drying of the nozzle can be suppressed as much as possible. Further, the capping motor 113 also functions as a drive source for a wiping mechanism 131 that drives a wiper blade (described later) disposed in the vicinity of the capping mechanism 130. That is, the wiping mechanism 131 also performs an operation of wiping off ink, dust, and the like attached to the ejection port surface of the recording head 9 by the driving force of the capping motor 113. Reference numerals 114, 115, 116, and 119 are motor drivers for driving the capping motor 113, the carriage motor 3, the paper feed motor 5, and the transport motor 110, and the operations of these motor drivers are controlled by the MPU 102. Is done.

  The console 106 is provided with a keyboard switch and a display lamp. The home position sensor 107 is provided near the home position of the carriage 2, detects that the carriage 2 on which the recording head 9 is mounted has reached the home position, and transmits a detection signal to the MPU 102. Reference numeral 109 denotes a sheet sensor installed in a portion (recording unit) facing the hair color in the main scanning direction of the recording head 9, and detects the presence or absence of a recording medium. Based on the detection signal from the sheet sensor 109, the MPU 102 can determine whether or not the recording medium fed from the paper feed tray 8 has been normally sent to the recording unit. Reference numeral 111 denotes a head driver for driving an electrothermal conversion element (ejection heater) provided in the recording head 9 in accordance with an image signal. Reference numeral 120 denotes a power supply unit for supplying power to the above-described units, and an AC adapter and a battery are used.

  Although not shown in FIGS. 1 and 3, the carriage 2 can be equipped with a plurality of ink tanks containing ink of each color together with the recording head 9. For the exterior part of the ink tank, for example, a resin such as PP or PE is formed by injection blow or the like, and then assembled using techniques such as ultrasonic welding, thermal welding, adhesion and fitting, etc. be able to. As an internal structure of the ink tank, a structure in which the external part itself functions as an ink chamber, a structure having an ink bag filled with ink, or a porous body inserted into the exterior portion, the ink is held by the capillary force and inside the tank. A structure that generates negative pressure can be employed. When a structure using an ink bag is used, negative pressure is generated in the ink bag by energizing the ink bag in the expansion direction by a spring mechanism or the like provided inside or outside the ink bag. Is possible. The negative pressure of the ink tank extends into each nozzle of the recording head, and it is possible to suppress ink leakage from the nozzle of the recording head by this negative pressure, and the ink is discharged to the discharge port formed at the nozzle end. A meniscus suitable for the above can be formed.

  Here, the configuration of the recording head 9 outlined above will be described again in more detail with reference to FIG. The recording head 9 is configured to convert electrical energy supplied based on recording data into thermal energy by an electrothermal conversion element, generate bubbles in the ink by the thermal energy, and eject ink droplets by the generated pressure of the bubbles. Is adopted. The ink ejection ports of the ejection port arrays 15a to 15f shown in FIG. 2 are formed in orifice plates 11a to 11f for ejecting 1280 inks of each color at an arrangement density of about 490 per cm. . Each of the illustrated discharge port arrays is a set of two discharge port arrays in which the ink discharge ports are arranged in a staggered manner, thereby realizing a high arrangement density. Reference numeral 9a denotes a plurality (six in this case) of ink supply ports provided corresponding to each orifice plate. Each ink supply port 9a communicates with a plurality of ink tanks containing different types of ink (dye black, pigment black, yellow, magenta, cyan ink). For this reason, it is possible to supply ink consumed by being discharged from each discharge port by discharge or suction from the recording head to the discharge port of the nozzle without interruption.

  FIG. 4 is a diagram showing the internal structure of the recording head 9. It is sectional drawing which shows the cross section cut | disconnected along the A-A 'line | wire and B-B' line | wire shown in this figure and FIG. As shown in FIG. 4, the ink supplied from the ink supply port 9a advances in the ink liquid chamber 24 in the H direction. When the ink liquid chamber 24 is filled to some extent, the ink advances in the J direction, passes through the filter 25, and then is supplied to the ink liquid chamber 26 and the plurality of ejection ports 15 formed in the orifice plate. By providing the filter 25 in the ink flow path, it is possible to prevent the mixed dust and the like from being mixed into the fine nozzle. The position of the discharge port surface where the discharge port 15 is formed corresponds to a position that is recessed by one step with respect to the TAB surface 30 in the orifice plate 11. This is to avoid contact between each ink ejection port and the recording medium as much as possible. Although FIG. 4 shows the structure of the ink liquid chamber in the dye black ink, the ink liquid chambers in the other inks have the same configuration. Further, in this specification, the nozzle refers to a portion constituted by an ejection port capable of ejecting ink, an ink flow path communicating with the ejection opening, and a heater provided in the ink flow path. A group of nozzles (nozzle rows) corresponding to a plurality of ejection port rows arranged on one orifice plate is also referred to as an ink ejection unit. Therefore, in the recording head 9 in the present embodiment, six ink discharge portions are formed corresponding to the six orifice plates.

  Hereinafter, the nozzle row for discharging the dye black ink is the ink discharge portion for dye black, the nozzle row for discharging the first pigment black ink is the first ink discharge portion for black pigment, and the nozzle row for discharging the second pigment black ink is the first. 2-pigment black ink ejection section, yellow ink ejection nozzle array as yellow ink ejection section, magenta ink ejection nozzle array as magenta ink ejection section, cyan ink ejection nozzle array as cyan ink ejection section Say.

  In the recording apparatus configured as described above, when a recording command is input from the console 106 or the host, the MPU 102 drives the paper feed motor 5 to start feeding the recording medium from the paper feed tray 8. At the same time, the MPU 102 further drives the capping motor 113 to release the capping mechanism from the recording head 9. As a result, the carriage 2 can be moved and scanned in the main scanning direction. Here, when image data for one recording scan is accumulated in the print buffer 121, the carriage motor 3 starts moving scanning of the carriage 2, and a recording operation on the recording medium is performed. Thereafter, an image is formed on the recording medium by repeatedly carrying the recording medium and performing carriage movement scanning. A cap 37 is provided at a predetermined position (hereinafter referred to as “home position”) that is within the reciprocal movement range of the recording head 9 in the main scanning direction and is out of the recording area.

  Next, the recovery operation of the recording head 9 executed in the recording apparatus having the above configuration will be described. In the present embodiment, in order to maintain the ejection performance of the recording head 9, 1. 1. suction recovery; 2. Wiping recovery Preliminary discharge is performed. Hereinafter, each recovery operation will be described sequentially.

(1) Suction Recovery In this embodiment, the ejection performance of the recording head 9 is from when each ink ejection portion (ejection port) of the recording head 9 is released from the cap means until the actual ejection of ink is started. As a recovery operation for maintaining the above, suction recovery is executed.

  FIG. 6 is a perspective view schematically showing a recovery mechanism including the suction recovery mechanism. The suction recovery mechanism shown here includes a pair of caps 201a and 201b held by the cap holder 202, a lifting mechanism (not shown) that lifts and lowers both caps together with the cap holder 202, and a pump 203a connected to each cap 201a and 201b. , 203b. The caps 201a and 201b are formed with suction ports 201c and 201d. The suction port 201c is connected to the pump 203a, and the suction port 201d is connected to the pump 203b. The pumps 203 a and 203 b can be driven independently using the driving force of the capping motor 113. The cap 201a is in close contact with the orifice plates 11d, 11e, and 11f of the recording head 9, and sucks yellow ink, magenta ink, and cyan ink. Similarly, the cap 201b is in close contact with the orifice plates 11a, 11b, and 11c of the recording head 9, and sucks the dye black ink, the first pigment black ink, and the second pigment black ink. The suction recovery mechanism is constituted by the suction recovery mechanism and the MPU 102 that controls the drive thereof.

  In the standby state in which the suction recovery operation is not performed, the caps 201a and 201b are held at an open position below the movement path of the wiper holder 23. In the case of performing the suction recovery operation, after the carriage 2 moves to the home position, the caps 201a and 201b are raised together with the cap holder 202 in the arrow Z direction by the lifting mechanism. As a result, the wiper cap 201a is in close contact with the orifice plates 11d to 11f, the cap 201b is in close contact with the orifice plates 11a to 11c, and the discharge ports of the nozzles are blocked from the outside air. Here, when the pumps 203a and 203b are driven, negative pressure is generated in the caps 201a and 201b. Due to this negative pressure, the ink mixed in the discharge port forming surface and each nozzle, and the ink having increased viscosity and adhering are sucked to the pump side and discharged. The above-described suction recovery operation is automatically performed every predetermined time or every predetermined number of discharges, thereby reducing the decrease in the discharge performance of the recording head 9.

(2) Wiping FIGS. 5 and 6 show a wiping mechanism that performs wiping for removing ink adhering to the ejection port surface of the recording head 9 by the above-described suction recovery operation. In FIG. 5, reference numeral 20 denotes a wiper blade (hereinafter referred to as a black side) for wiping the outer surfaces (discharge port surfaces) of the orifice plates 11a, 11b, and 11c for discharging the dye black ink, the first pigment black ink, and the second pigment black ink. This is called a wiper. Reference numeral 21 denotes a wiper blade (hereinafter referred to as a color side wiper) for wiping the orifice plates 11d, 11e, and 11f that discharge yellow ink, magenta ink, and cyan ink. The wiper blade 22 is a full-surface wiper for wiping off ink adhering to the entire bottom surface of the recording head 9 including the TAB surface to which each orifice plate is attached.

  As shown in FIG. 6, the wiper blades 20 and 21 and the wiper blade 22 are attached to a wiper holder 23 installed in the main body by a wiper fixing bracket. The wiper holder 23 can be reciprocated along two guide shafts 23 a installed along the sub-scanning direction (arrow y direction) by the driving force of the capping motor 113. Such a wiping mechanism and the MPU 102 that controls its operation constitute a wiping recovery means. When wiping is not performed, the wiper blades 20, 21 and the wiper blade 22 are held at an initial position (position shown in FIG. 6) retracted from the position facing the orifice plate of the recording head 9 located at the home position. .

  Further, at the time of wiping (wiping), the capping motor 113 is driven to move the wiper blades 20 and 21 and the wiper blade 22 together with the wiper holder 23 in the y1 direction of FIG. As a result, the entire orifice plate and the discharge port forming surface are wiped by the wiper blades 20 and 21 and the wiper blade 22. When the wiping operation (wiping) by the wiper is completed, the recording head 9 is moved out of the wiping area by the movement of the carriage 2. Thereafter, the wiper blades 20, 21, and 22 are moved in the opposite direction (y2 direction) to that at the time of wiping (wiping) by the movement of the wiper holder 23, and returned to the initial position.

(3) Preliminary ejection Ink adhering to the ejection port surface of the recording head 9 due to the wiping described above is pushed into the nozzle to mix colors, or ink adhering to the vicinity of the ejection port due to unwiping of the wiping is negative pressure of the nozzle The color mixture occurs by being pulled into the nozzle by. In order to discharge the mixed-color ink, preliminary discharge, which is an ink discharge operation that does not contribute to recording, is executed. This preliminary ejection is performed when the MPU 102 controls the head driver 111 according to the number of ejections of the recording head 9 and ejects ink from the recording head 9. Further, the number of ink droplets ejected in preliminary ejection after wiping is set by a setting process in the MPU 102 described later. Accordingly, the preliminary ejection unit that performs the preliminary ejection performed by the recording head 9 is configured by the MPU 102 and the head driver 111.

  Further, this preliminary discharge is executed as necessary not only after wiping but also during the printing operation. For example, preliminary ejection may be performed at the timing between each scan, and the preliminary ejection at this time may be performed for all nozzles, but the nozzles that have not been used in the previous recording scan and the frequency of use Alternatively, it may be performed only for the nozzles for which there are few. It is also possible to perform control such that the number of preliminary ejections is adjusted based on the frequency of nozzle use.

  The preliminary ejection as described above is executed before recording or during recording. In this embodiment, in any case, the preliminary ejection ink receiving port provided at a predetermined position facing the moving path of the recording head. Execute by moving the carriage to the end. When the width of the ink receiving opening has a width that can correspond to the recording head 9, the preliminary ejection by the recording head 9 can be completed in a batch with the carriage stopped at the position of the ink receiving opening. . However, in this case, it is necessary to prepare a wide ink receiving port, and there is a concern that the recording apparatus itself is increased in size. Accordingly, in this embodiment, an ink receiving port that can correspond to a nozzle row for one color of ink is provided, and the recording head 9 is configured to be able to sequentially perform preliminary ejection for each color at the position of the nozzle row for each color.

  By the way, in this embodiment, the wiper blades 20, 21, and 22 are comprised by rubber members, such as urethane. For this reason, as shown in FIG. 7, the wiper blade 21 absorbs ink adhering at the time of wiping (wiping) and swells as shown by an arrow a in FIG. 7, and then the ink is dried. Shrink as shown by arrow b in FIG. Thus, the wiper blade 21 is repeatedly deformed and deteriorated every time wiping recovery is performed. Further, the wiper blade 21 also deteriorates due to wear due to contact with the discharge port surface of the recording head 9. 7 and 8, only the wiper blade 21 is shown, but the wiper blades 21 and 22 are similarly deteriorated. When such wiper blade deterioration occurs, the amount of ink remaining on the head face after wiping increases each time wiping is repeated, and the greater the amount of ink left, the more negative the nozzle pressure The amount of ink drawn in increases. That is, the amount of ink remaining on the ejection port surface changes according to the degree of deterioration of the wiper blade 21. As a result, the amount of ink mixed in the nozzle also increases.

  Therefore, in the present embodiment, it is possible to reliably discharge the mixed-color ink in the nozzles by controlling the number of ejections in the preliminary ejection according to the state of deterioration of the wiper blade. The state of deterioration of the wiper blade is determined by the counted cumulative wiping count (cumulative wiping count). In addition, the relationship between the cumulative number of wipings that indicates the state of deterioration of the wiper blade and the minimum number of preliminary ejections required to reliably discharge the mixed color ink in the nozzle that increases with the deterioration of the wiper blade from the nozzle. A table to be represented is set in the RAM 103. FIG. 9 shows an example of this table. The number of preliminary ejections is determined from this table and the counted cumulative wiping count. Hereinafter, the recovery process in the present embodiment including the preliminary discharge performed after wiping will be described more specifically.

(Recovery processing sequence)
FIG. 10 is a flowchart showing a recovery processing sequence of the recording head 9 performed by the control system in the first embodiment of the present invention. As the recovery process of the recording head 9, first, the suction recovery process described in the above (1) is performed (step S101). Next, the wiping described in the above (2) is performed (step S102). The number of wiping executed at this time is added to the cumulative wiping count that has been cumulatively counted by the MPU 102, and the added value is stored in the EEPROM 122 shown in FIG. 3 as the updated cumulative wiping count. (Step S103).

  Once the wiping in step S102 is executed, the number of preliminary ejections is next determined from the cumulative number of wipings and a table for determining the number of preliminary ejections (step S104). As a table for determining the number of preliminary ejections, for example, the table shown in FIG. 9 is used. In this table, the cumulative number of wipings representing the degree of deterioration of the wiper blades 20, 21, 22 is divided into four stages, and the number of times to perform preliminary discharge is divided into four stages accordingly. That is, when the number of wipings is between 0 and 1000, the wiping performance of the wiper blades 20, 21, and 22 is less deteriorated than the number of wipings more than that, and therefore remains on the discharge port surface after wiping (after wiping). Ink amount is also small. For this reason, the amount of ink that is wiped off by the wiper blades 20, 21, and 22 is pushed into the nozzle, and the ink near the discharge port is drawn in by the negative pressure of the nozzle. Accordingly, the number of ejections 400 times is set as the minimum necessary number of preliminary ejections, and the preliminary ejection of the above-described (3) is performed by the number of ejections (step S105). As a result, ink adhering to the periphery of the ejection opening and ink mixed in the nozzle are discharged, and the ink ejection performance is reliably recovered.

  Further, if the number of wiping times is between 1001 and 2000 times, the wiper blades 20, 21, and 22 are more deformed than when the wiping number is 0 to 1000 times, and the wiping performance of the wiper blades is reduced. is doing. For this reason, by increasing the number of preliminary ejections to 800, the ink adhering to the periphery of the ejection port of the recording head or the ink mixed in the nozzle can be reliably discharged, and the ejection performance of the nozzle can be sufficiently achieved. Can be recovered. Further, if the number of wipings is between 2001 and 3000, the deformation of the wiper blades 20, 21, and 22 is considerably advanced, and it can be considered that the wiping performance is drastically deteriorated. Therefore, the number of preliminary ejections is set to 1200. . Further, in a situation where the number of wiping operations is 3000 times or more, it can be considered that the wiping performance of the wiper blades 20, 21, and 22 is significantly reduced, so that 2000 preliminary ejections are performed.

  As described above, in the first embodiment, preliminary ejection is performed with an appropriate number of ejections that is not excessive or insufficient in accordance with the state of deterioration (degradation) of the wiping performance of the wiper blades 20, 21, and 22. For this reason, the ink adhering to the peripheral edge of the discharge port of the recording head or the ink mixed in the nozzle can be reliably discharged, and the ink discharge performance can be sufficiently recovered. Therefore, it is possible to reliably remove ink mixed in the nozzle after wiping, and a high-quality recorded image can be obtained.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment as well, the configuration shown in FIGS. 1 to 6 is provided as in the first embodiment, and suction recovery processing, wiping, and the like are performed in (1) and (2) of the above embodiment. The same processing as that described in) is performed. In the second embodiment, the preliminary discharge performed after wiping is performed in accordance with the conditions such as the elapsed time from the previous wiping and the environment when the previous wiping is executed.

  Hereinafter, the recovery process executed in the second embodiment will be specifically described with reference to the flowchart of FIG. First, prior to the start of the recording operation, the suction recovery process described in (1) is performed (step S111), and then the wiping described in (2) is performed (step S112). In this embodiment, temperature and humidity sensors and timers (not shown) are used to obtain temperature and humidity environment information and information on the elapsed time from the previous wiping to the current wiping, and the information is shown in FIG. The data is stored in the EEPROM 122 shown. This environment and time information is used at the next wiping.

  When wiping is executed in step S112, the elapsed time from the previous wiping to the current wiping is acquired from the EEPROM (step S113). Further, environment (temperature, humidity) information when the previous wiping recovery process is performed is acquired from the EEPROM 122 shown in FIG. 3 (step S114). Thereafter, a weighting coefficient for determining a count value (number of wiping operations) to be added after the current wiping is determined with respect to the cumulative number of wiping operations (cumulative wiping operation count) counted until the previous wiping. This determination is made based on at least one of the acquired elapsed time and environment information. That is, in the present embodiment, it is possible to specify in advance whether the weighting coefficient is determined in consideration of only the elapsed time or in consideration of environmental information. In step S115, based on the designation, it is determined whether only the elapsed time is considered or whether environmental information is also taken into account (elapsed time + environment). Here, for example, when it is specified to determine the weighting coefficient based only on the acquired elapsed time, the processing of steps S117 to S120 is performed.

  In step S117, it is determined whether the elapsed time T from the previous wiping to the current wiping is less than 12 hours, 12 hours or more and less than 24 hours, or 24 hours or more. When the weighting coefficient is determined based only on the elapsed time, the above-described elapsed time T is the time actually measured by the timer (actual elapsed time T0) from the previous wiping to the current wiping. In step S117, when it is determined that the elapsed time T is a relatively short time of less than 12 hours, it is determined that there is little deformation due to swelling of the wipe blade after ink absorption and shrinkage due to drying of the ink, The weighting coefficient (tc) is set to 1 (step S118). Thereafter, “1” is added as the current wiping count to the cumulative wiping count counted until the current wiping, and this is set as the corrected cumulative wiping count (corrected cumulative wiping count) (step S121).

Further, when the elapsed time T is 12 hours (half day) or more and less than 24 hours, it is determined that there is little deformation due to swelling after ink absorption and shrinkage due to drying of the ink, and the weighting coefficient is set to 1.5. (Step S119). Thereafter, “1.5” is added to the cumulative wiping count as the corrected wiping count obtained by correcting the current wiping count, and this is set as the corrected cumulative wiping count (corrected cumulative wiping count) (step S121).
When the elapsed time T is 24 hours (one day) or more, it is determined that there is sufficient deformation due to swelling after ink absorption and shrinkage of the wiper blade due to drying of the ink, and the weighting coefficient (tc) is set to 2. .0 (step S120). Then, “2” is added to the cumulative wiping count as the corrected wiping count obtained by correcting the current wiping count, and this is set as the corrected cumulative wiping count (corrected cumulative wiping count) (step S121).

  On the other hand, if it is determined in step S117 that the environment information is taken into account in addition to the actual elapsed time T0 measured by the timer when the weighting coefficient is determined, the actual elapsed time measured by the timer is determined. The corrected elapsed time corrected by weighting T0 is defined as a measurement time T (step S115). The process of correcting the elapsed time T according to the environmental information (temperature, humidity) in this way is shown in the flowchart of FIG.

  In the process shown in FIG. 12, first, the relationship between the temperature t detected by the temperature / humidity sensor and the room temperature to is determined (step S1161). Here, when the temperature t is lower than the room temperature to (18 ° C. to 25 ° C.) (t <to), the actual elapsed time T0 acquired in step S113 is multiplied by a weighting coefficient (tc) of 0.5 ( Step S1162). Therefore, when the actual elapsed time T0 is 1 hour, the weighted corrected elapsed time (first corrected elapsed time) T1 is 30 minutes.

  If the temperature t is normal temperature to (t = to), the actual elapsed time T is multiplied by “1” as the weighting coefficient (tc) (step S1163). Therefore, when the actual elapsed time T is 1 hour, the first corrected elapsed time T1 is weighted for 1 hour. Further, when the temperature t> ordinary temperature, the actual elapsed time T is multiplied by 1.5 as a weighting coefficient (tc) (step S1164). Therefore, when the actual elapsed time T is 1 hour, the weighted first corrected elapsed time T1 is 1 hour 30 minutes.

  Thereafter, the relationship between the humidity h detected by the temperature / humidity sensor and the standard humidity ho (50% to 70%) is determined (step S1165). Here, when the detected humidity h is lower than the standard humidity ho (h <ho), the ink absorption and drying proceed sufficiently. For this reason, the second correction elapsed time T2 is obtained by multiplying the first correction elapsed time T1 calculated in the aforementioned steps S1162 to S1164 by a weighting coefficient (hc) of 1.5 (step S1166). Therefore, when the first correction elapsed time T1 is 1 hour, the second correction elapsed time T2 is 1 hour 30 minutes.

When the humidity h is the standard humidity ho (h = ho), the second corrected elapsed time T2 is obtained by multiplying the first corrected elapsed time T1 by a weighting coefficient (hc) of 1.0 ( Step S1167). Therefore, when the first correction elapsed time is 1 hour, the second correction elapsed time T2 is also 1 hour (1H). Further, when the humidity h is higher than the standard humidity ho (h> ho), the ink absorption and drying do not proceed so much, so the first correction elapsed time T1 is multiplied by 0.5 as the weighting coefficient (hc). . Accordingly, when the first correction elapsed time T1 is 1 hour, the second correction elapsed time T2 is 30 minutes. The above correction processing for obtaining the elapsed time T (= second corrected elapsed time T2) can be expressed by the following (Equation 1).
Second corrected elapsed time T2 = T0 (actual elapsed time) × tc (temperature weighting coefficient) × hc (humidity weighting coefficient) (Equation 1)
When the second corrected elapsed time T2 is calculated as described above, the processing of steps S117 to S120 is performed with the second corrected elapsed time T2 as the elapsed time T, and the weighting coefficient is determined. (Step S117). Thereafter, according to the determined weighting coefficient, a current wiping count (current wiping count) count value to be added to the cumulative wiping count is calculated (step S121). The calculation of the count value is performed in the same manner as when the wiping weighting coefficient (wiping weighting number) tc is set in consideration of only the elapsed time T described above.

That is, the count value is determined as follows according to the length of the corrected second corrected elapsed time T2.
When the second correction elapsed time T2 <12H: Count value once 24H> When the second correction elapsed time T2 ≧ 12H: Count value 1.5 times When the second correction elapsed time T ≧ 24H: Count value 2 times

Further, the determined count value is added to the cumulative count value to calculate a new cumulative count value (step S122), and the preliminary ejection number is determined based on the cumulative count value and the table shown in FIG. Discharging is performed (step S123).
By performing the above-described series of processing, in the second embodiment, it is possible to determine the state of the wiper blade in consideration of the elapsed time from the previous wiping and the environment (temperature, humidity). . For this reason, it is possible to more appropriately determine the number of preliminary discharges to be performed after wiping, and it is possible to more reliably remove the ink mixed in the nozzle, thereby obtaining a high-quality recorded image. Can do. Furthermore, since excessive preliminary ejection can be suppressed, wasteful consumption of ink can be reduced, and running cost is improved.

  In the second embodiment, in addition to the actual elapsed time T0, a process for setting the number of preliminary discharges required in consideration of the environment (temperature, humidity) is performed, but only the actual elapsed time T0 is set. It is also possible to determine the number of preliminary discharges in consideration of the above. In this case, the processing of steps S114 to S116 in FIG. 11 is not necessary.

Furthermore, weighting according to the type of ink can be performed in order to more appropriately determine the state of the wiper blade. The wiper blade has different ink absorbency depending on the type of ink, and tends to deteriorate as the ink is absorbed. For this reason, for example, ic (ink weighting coefficient) is added to the formula for calculating the elapsed time T in (Equation 1), and the elapsed time T is obtained by the following (Equation 2).
T (corrected elapsed time) = T0 (actual elapsed time) × tc (temperature weighting coefficient) × hc (humidity weighting coefficient) × ic (ink weighting coefficient) (Equation 2)

  Here, the ink weighting coefficient is determined according to the absorbability of the ink wiped by the wiper blade to the wiper blade. For example, among the dye black ink, the first pigment black ink, and the second pigment black ink wiped by the wiper blade 20, the pigment ink has high viscosity and low absorbability to the wiper blade, and the wiper blade hardly swells and contracts. . Therefore, the ink weighting coefficient is set to 0.8. On the other hand, low-viscosity dye inks such as yellow ink, magenta ink, and cyan ink wiped by the wiper blade 21 have high absorbability to the wiper blade, and the wiper blade is likely to swell and contract. Therefore, the ink weight is set to 1.2.

  After calculating the corrected elapsed time T in consideration of the type of ink, the processing of the above steps S117 to S120 is performed based on the corrected elapsed time T, and as described above, the current wiping number to be added after the wiping operation is determined. One, 1.5, or 2 times. Thereafter, the corrected cumulative count number (corrected cumulative number) is obtained by adding this count value to the previous wiping cumulative count number (cumulative wiping number) (step S121). Based on the corrected cumulative count, the number of preliminary ejections is determined (step S122), and preliminary ejection is performed (step S123). According to this, since it becomes possible to judge the ejection performance of the wiper blade more accurately in consideration of the elapsed time, environment, and ink type, it is possible to reliably discharge the mixed color ink in the nozzles by preliminary ejection. This makes it possible to suppress excessive preliminary discharge. Accordingly, high-quality image formation can be realized, and excessive preliminary discharge can be suppressed, and the running cost can be further reduced.

(Other embodiments)
In the second embodiment, the actual elapsed time from the previous wiping to the current wiping is corrected by factors related to the deterioration of the wiper blade, such as temperature, humidity, and ink type, and the corrected elapsed time is used as the corrected elapsed time. Based on this, the case of correcting the number of wiping operations this time is shown. In other words, in the second embodiment, the corrected cumulative wiping count is obtained from the sum of the cumulative wiping count up to the previous wiping and the current corrected wiping count. However, the sum of the previous wiping count and the current wiping count may be multiplied by a weighting coefficient determined based on at least one of the environmental temperature, humidity, and ink type.

  Further, in each of the above embodiments, the current wiping count is set to one, and the weighting coefficient is multiplied by tc to obtain the current corrected wiping count. However, the number of times of each wiping can be set to a plurality of times (two or more times). In this case as well, the current correction wiping count (current correction wiping count) is obtained by multiplying the plurality of wiping counts by the weighting coefficient tc. Should be determined.

  Further, in each of the above-described embodiments, the case where the number of wipings performed after the current wiping is corrected based on the factors related to the deterioration of the wiper blade as described above has been described as an example. However, based on the above factors, it is also possible to correct the number of wiping operations accumulated up to the previous time.

  In addition, the amount of ink adhering to the discharge port surface increases as the amount of ink discharged or discharged during recording operation or suction recovery increases, and the amount of ink adhering to the discharge port surface increases as the amount of ink adhering to the wiper blade increases. The amount of absorption increases and the wiping performance deteriorates. Therefore, the actual number of wiping or elapsed time may be weighted based on the amount of ink ejected between the previous wiping and the current wiping. This ink amount can be obtained, for example, from the number of ink droplets ejected in the recording operation, the ink suction amount at the time of suction recovery, and the like.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 9 Recording head 11a Dye black orifice plate 11b 1st pigment black orifice plate 11c 2nd pigment black orifice plate 11d Yellow orifice plate 11e Magenta orifice plate 11f Cyan orifice plate 20, 21 Wiper 102 MPU
110 Conveyance motor 120 Wiping mechanism 203a, 203b Suction pump

Claims (9)

In an ink jet recording apparatus that performs recording using a recording head having a nozzle capable of ejecting ink,
A wiper blade for wiping off ink adhering to the ejection port surface where the ejection port of the nozzle of the recording head is formed;
Preliminary wiping means for performing ejection of ink droplets that do not contribute to recording from the ejection port after wiping the ejection port surface by the wiper blade;
Determining means for determining the wiping performance of the wiper blade with respect to the discharge port surface;
An ink jet recording apparatus comprising: a control unit that controls to increase the number of ink droplets ejected by the preliminary ejection unit as the wiping performance of the wiper blade determined by the determination unit decreases.   The inkjet recording apparatus according to claim 1, wherein the determining unit determines whether the performance of the wiper blade is deteriorated based on a cumulative number of times of wiping of the discharge port surface by the wiper blade.   The determination means corrects the cumulative wiping count of the discharge port surface by the wiper blade according to the elapsed time from the previous wiping time to the current wiping time, and increases or decreases the corrected cumulative wiping frequency obtained by the correction. 2. The ink jet recording apparatus according to claim 1, wherein a magnitude of a decrease in wiping performance of the wiper blade is determined based on the determination.   The determination means corrects the elapsed time from the previous wiping time to the current wiping time based on the environmental information acquired from the previous wiping time to the current wiping time, and the correction progress obtained by the correction. Correcting the cumulative number of wiping of the discharge port surface by the wiper blade based on time, and determining the degree of decrease in the wiping performance of the wiper blade based on the corrected cumulative wiping number obtained by the correction. The inkjet recording apparatus according to claim 1.   5. The inkjet recording according to claim 1, wherein the corrected elapsed time is a time calculated by multiplying the elapsed time by a weighting coefficient determined in accordance with the environmental information. apparatus.   The determination unit corrects the elapsed time from the previous wiping time to the current wiping time according to the absorbability of the ink wiped by the wiper blade with respect to the wiper blade, and the corrected elapsed time obtained by the correction The inkjet recording apparatus according to claim 1, wherein the number of wiping of the discharge port surface is corrected based on   The corrected cumulative wiping count is a number obtained by adding the corrected wiping count obtained by multiplying the cumulative wiping count up to the previous wiping cycle by the wiping weighting factor for the current wiping, and the wiping weighting factor The ink jet recording apparatus according to claim 2, wherein is determined according to the elapsed time.   6. The ink jet recording apparatus according to claim 4, wherein the environmental information is information obtained from at least one of temperature and humidity. In an inkjet recording apparatus that performs recording using a recording head having a nozzle capable of ejecting ink, the recording head recovery method includes wiping the ejection port surface of the recording head where the ejection port of the nozzle is formed with a wiper blade. And
A preliminary ejection step of performing ejection of ink droplets that do not contribute to recording from the ejection port after wiping the ejection port surface by the wiper blade;
A determination step of determining the wiping performance of the wiper blade with respect to the discharge port surface;
And a control step of controlling the number of ink droplets ejected by the preliminary ejection means to increase as the wiping performance of the wiper blade determined in the determination step decreases. .

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