JP2012218399A - Inkjet recording apparatus - Google Patents

Abstract

In the case of ink that is solidified by heat, not only the viscosity increases due to evaporation but also the cleaning performance of the recording head discharge port surface extremely decreases.
An ink jet recording apparatus according to the present invention includes a recording head that scans along a recording medium and ejects ink, and a heating unit that heats an area scanned by the recording head with respect to the recording medium. The recording apparatus includes a belt-like wiping member that is placed at a position opposite to the discharge port surface where the liquid discharge port of the recording head is formed and rubs the discharge port surface. A cleaning mechanism that performs wiping operation of the discharge port surface by moving the wiping member and the discharge port surface in contact with each other during scanning, and the higher the heating temperature by the heating means, the higher the cleaning mechanism. This increases the frequency of cleaning the discharge port surface.
[Selection] Figure 7

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging ink from a recording head to a recording medium.

  In an ink jet recording apparatus, it is known that ink adheres to the surface (hereinafter referred to as a face surface) of a recording head in which ejection ports (nozzles) are formed, thereby preventing normal ejection. Therefore, it is common to provide a cleaning mechanism for wiping off ink adhering to the face surface using a wiper blade.

  As an example of such an operation, Patent Document 1 discloses a method of determining a wiping timing by using a timer and a count of the number of ink ejections by a recording head (dot count) in combination.

JP 07-125228 A

  By the way, in recent years, for the purpose of improving the image fastness and the degree of freedom in selecting a recording material, the function of the ink has been improved. For example, an ink jet recording apparatus using an ink that is solidified by heat is used. Can be mentioned. In such an ink, not only the viscosity increases due to evaporation but also the cleaning property extremely deteriorates due to a phase change accompanying evaporation or heating, or due to dispersion destruction and solidification due to concentration increase due to evaporation.

  In order to solve such a problem, the technique disclosed in Patent Document 1 does not consider the deterioration of the cleaning property by the heater for fixing the ink on the recording medium, and thus there is a problem that the cleaning property becomes insufficient. It was. On the other hand, when the cleaning frequency is simply increased, the function (water repellency or hydrophilicity) of the face surface that is usually treated with water repellency or hydrophilic treatment deteriorates at an early stage and the life of the recording head is shortened. is there.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention is an ink jet recording apparatus capable of suppressing deterioration of a recording head as much as possible and performing cleaning at an appropriate timing even when ink that can be firmly fixed on a face surface is used. Is to provide.

  The ink jet recording apparatus of the present invention includes a recording head that is scanned along a recording medium and ejects ink, and a heating unit that heats the recording medium in a region scanned by the recording head.

  The present invention is premised on such a recording apparatus, and is a belt-like wiping that is placed at a position opposite to the ejection port surface on which the ink ejection port of the recording head is formed and rubs against the ejection port surface. A cleaning mechanism that has a member and performs a wiping operation of the discharge port surface by moving the wiping member and the discharge port surface in contact with each other during scanning of the recording head, As the heating temperature by the means is higher, the cleaning frequency of the discharge port surface by the cleaning mechanism is increased.

  According to the present invention, in contrast to setting the heater temperature high in order to improve the ink fixing property to the recording medium, the ink fixing state on the ejection port surface of the recording head is predicted and the frequency of cleaning the ejection port surface is set. In order to increase, the discharge port surface can be cleaned at an appropriate timing. As a result, it is possible to obtain a good image free from the influence of ejection failure due to ink fixation without reducing the throughput over the life of the head.

1 is an overall view of a recording apparatus applicable to the present invention. It is a recording area expansion schematic diagram of a recording apparatus applicable to the present invention. FIG. 3 is a schematic diagram of a recording head applicable to the present invention. FIG. 4 is a schematic diagram of an ejection unit mounted on a recording head applicable to the present invention. 1 is an overall control diagram of a recording apparatus applicable to the present invention. It is a characteristic view of an ink suitable for the present invention. 6 is a flowchart and a table for setting a cleaning frequency between print scans according to the first exemplary embodiment. 10 is a flowchart and a table for setting a cleaning frequency between printing scans according to the second embodiment.

  Embodiments to which the present invention can be applied will be described below with reference to the accompanying drawings.

<Outline of recording device>
FIG. 1 shows the appearance of an ink jet recording apparatus (hereinafter referred to as a printer) applicable to the present invention. The printer shown in this figure is a so-called serial scan type printer, and forms an image by scanning (main scanning) the recording head in a direction (main scanning direction) orthogonal to the conveyance direction of the recording medium P. .

  Next, the configuration of the printer and the outline of the operation during recording will be described with reference to FIG. First, recording is performed from the spool 6 holding the recording medium P by a paper feed motor (not shown) (see the paper feed motor 5 in FIG. 5) and a paper feed roller (not shown) driven through a gear. The medium P is conveyed. On the other hand, the carriage unit 2 is scanned along a guide shaft 8 extending in a direction orthogonal to the conveyance direction by a carriage motor (not shown) at a predetermined conveyance position. In this scanning process, at a timing based on the position signal obtained by the encoder 7, from an ink discharge port (nozzle) of a recording head (see recording head 9 in FIG. 3) that is detachably attached to the carriage unit 2. A discharge operation is performed, and a certain bandwidth corresponding to the nozzle arrangement range is recorded. Thereafter, the recording medium P is transported and recording is performed for the next bandwidth. In such a printer, there is a case where the recording medium is transported for the bandwidth between each scan, and if necessary, the transport for the bandwidth is not performed for each scan, and the transport is performed after performing a plurality of scans. May be performed. Also, after recording data thinned out by a predetermined mask every scan, paper feeding around 1 / n band is performed, and scanning is performed again, so that the nozzles involved in recording differ for one image area. In some cases, a method (so-called multi-pass printing) for completing an image by performing a plurality of scans and conveyances is performed. A flexible wiring substrate 10 for supplying a signal pulse for ejection driving, a head temperature adjustment signal, and the like is attached to the recording head 9. The other end of the flexible substrate 10 is connected to a control circuit (described later) having a control circuit that executes control of the printer. A carriage belt can be used to transmit the driving force from the carriage motor to the carriage unit 2. However, instead of the carriage belt, for example, a lead screw that is rotationally driven by a carriage motor and extends in the main scanning direction, and an engagement portion that is provided on the carriage unit 2 and engages with a groove of the lead screw, etc. Other driving methods can also be used. The fed recording medium P is conveyed while being sandwiched between a paper feed roller and a pinch roller (not shown) and guided to a recording position on the platen 4 (main scanning area of the recording head 9). In the normal resting state, the discharge port surface (also referred to as a face surface) on which the discharge port of the recording head 9 is formed is capped, so that the cap is opened prior to recording and the recording head 9 or the carriage unit 2 is opened. Make the scan ready. After that, when data for one scan is accumulated in the buffer, the carriage unit 2 is scanned by the carriage motor, and recording is performed as described above.

  FIG. 2 is an enlarged schematic view of the recording scanning area of FIG. 1 (a view of the configuration of the heating mechanism and the cleaning mechanism around the platen as viewed from the conveyance direction of the recording medium P). Along with the recording, the carriage unit 2 reciprocates in the direction of the arrow in the figure. The heater 1 has a length equivalent to the maximum recording width under the platen 4 so that the ink on the recording material P can be heated and fixed immediately after ink is ejected from the recording head mounted on the carriage unit 2. Arranged. Appropriate control is performed to maintain the heating temperature set according to the type of recording material P and the recording mode. Although FIG. 2 shows an example in which the recording medium P is heated from under the platen 4, the present invention is not limited to this, and a heater may be provided immediately above the carriage unit 2. A cleaning mechanism 30 is provided on each outer side of the recording area in the carriage unit moving direction. Generally, in order to wipe off ink adhering to the face surface, wiping is performed by rubbing the face surface with a rubber wiper. However, in inks that are heated as described above as preferred examples of the present embodiment, a part of the components change phase by heating to promote fixation, and when subjected to high temperature once, the phase change occurs. The viscosity is considerably higher than that of the ink.

  Since the heater 1 is disposed immediately below the carriage unit 2, the face surface is likely to become hot during recording. Accordingly, the viscosity of the ink adhering to the face surface is high, so that it is difficult to remove by general wiping. When wiping with the conventional wiping mechanism is difficult, or when the ink residue after wiping is likely to solidify, porous urethane foam, melamine foam, polyolefin, PET, or nylon is used as the wiping member. The head may be wiped using a web (nonwoven fabric) or the like. The cleaning mechanism 30 suitable for the present embodiment is an example of a cleaning mechanism using such a web.

  In the cleaning mechanism 30, a web 31 formed in a belt shape is wound around a supply roller 32 in a roll shape, and the other end is fixed to a take-up roller 33. It has a tensioned form. A push-up member 34 is disposed between the supply roller 32 and the take-up roller 33, and the push-up member 34 moves up and down by controlling a motor (not shown) (see the cleaning mechanism control motor 35 in FIG. 5). The web 31 stretched between the supply roller 32 and the take-up roller 33 moves up and down. The portion of the web 31 that is moved up and down by the push-up member 34 is disposed at a position that can face the face surface. Therefore, when the push-up member 34 is on the lower side and the web 31 is in the position indicated by the broken line in FIG. 2, even if the carriage unit 2 passes above the cleaning mechanism 30, The web 31 does not come into contact, and therefore the face surface is not cleaned. On the other hand, when the push-up member 34 is on the upper side and the web 31 is at a position higher than the face surface of the recording head 9 as indicated by the solid line in FIG. 2, the carriage unit 2 has passed over the cleaning mechanism 30. Sometimes the face surface abuts the web 31. At that time, most of the ink adhering to the face surface is wiped off by the web 31 so that cleaning (wiping operation) is performed. Then, after the carriage unit 2 has passed, the web 31 is wound up by the width of the push-up member 34, so that the next cleaning can be performed using the web 31 in a clean part. Since the wiping force increases as the position of the push-up member 34 increases, the cleaning strength of the face surface can be adjusted by adjusting the position of the push-up member 34. As described above, since the face surface can be cleaned only by relatively passing the face surface over the cleaning mechanism 30, the recording scan can be performed between recording scans (that is, after the recording scan is performed, without reducing productivity). Wiping cleaning can be performed during the recording scan. In order to further improve the cleaning performance, the web 31 is preferably impregnated with an ink solvent when the web 31 as a wiping member is brought into contact with the face surface.

  In addition, a cap 36 is provided on one of the outer sides of the recording area in the moving direction of the carriage unit 2 separately from the cleaning mechanism. The cap 36 can be moved up and down by controlling a motor (not shown) (see the capping motor 37 in FIG. 5). In the raised position, for example, the cap 36 can be capped for each of the face surfaces of three ejection portions of the recording head, which will be described later, to protect the cap 36 during non-recording operation, or to perform suction recovery. is there. Further, the cap 36 is set at a lowered position that avoids interference with the recording head mounted on the carriage unit 2 during a recording operation, and can receive preliminary ejection ink by facing the face surface of the recording head. It is.

<Recording head>
FIG. 3 is a schematic perspective view of the recording head 9 mounted on the carriage unit 2 of the printer as viewed obliquely from above with respect to the direction in which ink is ejected. Here, the recording head 9 includes inks of different color tones (including color and density), for example, black, along a main scanning direction S that is preferably orthogonal to the conveyance direction of the recording medium P. A plurality of ejection units 11 to 16 that can eject ink of (Bk), light cyan (Lc), cyan (C), light magenta (Lm), magenta (M), and yellow (Y) are arranged in parallel. Ink is supplied from the ink introduction unit 23 to each ejection unit via an ink flow path inside the recording head 9. Ink is introduced into the ink introduction part 23 from a later-described ink tank through a supply tube.

FIG. 4 is a schematic perspective view of each discharge unit. Each ejection unit is of a type that uses, for example, thermal energy that causes film boiling in the ink in response to energization, as energy used to eject the ink. Specifically, each discharge unit has a substrate 51 formed by juxtaposing two rows of heat generating portions in which heat generating portions 52 are formed at a predetermined pitch. 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 in which a plurality of nozzles 55 corresponding to each heat generating portion 52 and a plurality of ink paths 59 for supplying ink from the ink supply port 56 corresponding to each of the nozzles 55 are formed. The (orifice plate) 54 is joined to form a discharge unit. In each heat generating portion row, the heat generating portions 52 and the nozzles 55 are shifted from each other by a half pitch, thereby realizing a desired recording resolution. Here, it is possible to set the same recording density and the number of nozzles for each of the ejection units 11 to 16 shown in FIG. In the present embodiment, 1280 nozzles are arranged at a density of about 490 nozzles per centimeter for each color in the discharge units 11 to 16. In this example, an ejection unit that ejects ink in a direction in which the heat generating unit 52 intersects the substrate 51 is used. However, an ejection unit that ejects ink in a direction along the main surface of the substrate 51. <Control system configuration example>
FIG. 5 shows a configuration example of a control circuit applicable to the printer according to the present invention. 5, the printer shown in FIG. 5 has a programmable peripheral interface (hereinafter referred to as PPI) 101. The PPI 101 receives a command information (command) sent from the host computer 100 and a recording information signal including recording data, transfers it to the MPU 102, and sends printer status information to the host computer 100 as necessary. To do. The PPI 101 performs input / output with a 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 for the user. Further, the PPI 101 receives a signal input from a sensor group 107 including a home position sensor for detecting that the carriage unit 102 or the recording head 9 is at the home position, a capping sensor, and the like.

  An MPU (microprocessing unit) 102 controls each part in the printer according to a control program stored in the control ROM 105 and corresponding to processing procedures and settings (including the face surface cleaning frequency, which is a feature of the present invention). .

  Further, the printer includes a RAM 103, a font generation ROM 104, a control ROM 105, a print buffer 121, drivers 110, 111, 113 to 116, a sheet sensor 109, a power supply unit 120, and the like.

  A RAM 103 is a RAM for storing received signals or used as a work area for the MPU 102 and temporarily storing various data. The font generation ROM 104 stores pattern information such as characters and records corresponding to the code information, and outputs various pattern information corresponding to the input code information. The print buffer 121 is a print buffer for storing the recording data expanded in the RAM 103 or the like, and has a capacity for M line recording. In addition to the above control program, the control ROM 105 can store fixed data corresponding to data used in the cleaning control process described later. These units are controlled by the MPU 102 via the address bus 117 and the data bus 118.

  The drivers 110 and 113 to 116 are drivers for driving the heater 1, the cleaning mechanism control motor 35, the capping motor 37, the carriage motor 3, and the paper feed motor 5 according to the control of the MPU 102.

  The sheet sensor 109 detects the presence or absence of the recording medium P, that is, whether or not the recording medium P has been supplied to a position where recording by the recording head 9 is possible.

  The head driver 111 is a driver for driving the heat generating portion 52 of the recording head 9 according to the recording information signal.

  The power supply unit 124 is a power supply unit that supplies power to the above-described units, and includes an AC adapter and a battery as a drive power supply device.

  In the recording system including the printer and the host computer 100 that supplies a recording information signal to the printer, when recording data is transmitted from the host computer 100 via a parallel port, an infrared port, a network, or the like, the head portion thereof is used. The required 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 size, A1 size, A2 size, B0 size, B1 size, B2 size, etc.), recording quality (fast, flawless, standard, clean, specific color enhancement, monochrome / color type, etc.), paper feed The route (determined according to the form and type of the recording medium feeding means provided in the printer. For example, roll paper, manual feed, etc.) and the presence / absence of automatic object discrimination. 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, the number of recording passes when performing the above-mentioned multi-pass recording, carriage speed, recording head height setting, ink ejection amount per recording medium unit area, recording direction, heater temperature, There is a type for determining the cleaning frequency of the face surface set based on the sequence. In addition, the mask type for data thinning applied when performing multi-pass printing, the driving conditions of the recording head 9 (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 There are also medium transport conditions, carriage scanning speed, and the like.

  A detailed description will be given below based on examples. The various setting values shown in each embodiment are merely examples, and do not limit the present invention.

"Example 1"
FIG. 6 shows ink characteristics suitable for the printer according to the present invention. The ink applied to the present invention is an ink in which a part of the components changes phase when heated to promote fixation, and FIG. 6 shows the relationship between the water evaporation and the phase change. The Y axis is the temperature, the X axis is the standing time at that temperature, the broken line indicates the timing when moisture evaporation is completed, and the solid line indicates the timing when the phase change starts.

  As shown in FIG. 6, it can be seen that if the ink is left at the same temperature, the water is first evaporated, and further, if the heating is continued, a phase change occurs. It can also be seen that this change is accelerated as the temperature increases. With respect to the ink, cleaning is possible if the moisture is not evaporated (stage 1), or if the moisture is evaporated but the phase is not changed (stage 2). However, when it reaches a state where the phase change has started (step 3), it becomes firmly fixed, and cleaning becomes difficult.

  Therefore, it is necessary to perform cleaning at an appropriate timing based on these. An example of a cleaning frequency setting sequence used for the print head cleaning operation will be described with reference to the flowchart shown in FIG.

  In setting the recording medium P in step 701, the recording medium type is set (step 702). Heater temperature information to be set is acquired for each recording medium type (step 703), and based on that information, in step 704, the recording scan for the face surface is performed (from the recording scan to the next recording scan). Determine the cleaning frequency.

  Here, the recording medium type is specified based on the user selection information when the recording medium is set. However, the present invention is not limited to this, and the recording medium type is specified based on information obtained by automatic selection by a separate sensor or the like. May be implemented. If the heater temperature setting means is provided in the printer and can be selected by the user, the cleaning frequency is determined based on the selected heater temperature.

  The setting of the cleaning frequency between recording scans for the face surface is performed with reference to the table shown in FIG. The table shown in FIG. 7B is an example in which the longest value (2 seconds) of the print scanning time on the heater is set as a base. Under the condition of 40 ° C., referring to FIG. 6, it is expected that moisture evaporation is completed by 10 seconds, phase change starts by 18 seconds, and cleaning becomes difficult. Based on this, the cleaning is set to be performed once every 5 scans (10 seconds). On the other hand, when the temperature of the heater is raised to 60 ° C., according to FIG. 6, it is expected that moisture evaporation is completed by 2 seconds, phase change starts by 4 seconds, and cleaning becomes difficult. . Therefore, the cleaning frequency is increased from 40 ° C., and it is set to be performed once every scan (2 seconds).

  In the above description, the cleaning frequency is defined based on the heater temperature. However, the cleaning frequency is not limited to this, and the cleaning frequency may be defined based on the surface temperature on the recording medium.

  Based on the above flow, when the recording medium is set, a cleaning frequency between recording scans for the face surface is set, and when recording data is received, cleaning is performed based on the set value.

"Example 2"
In the first embodiment, the cleaning frequency between the recording scans for the face surface is set for each heater temperature. However, in the second embodiment, the recording scanning time on the heater is further considered as shown in FIG. An example is shown. The recording scanning time on the heater is proportional to the carriage scanning speed. An example in which the carriage scanning speed is acquired and the cleaning frequency is set based on the carriage scanning speed will be described below.

  An example of a cleaning frequency setting sequence used for the print head cleaning operation will be described with reference to the flowchart shown in FIG.

  Steps 801 to 803 are the same as those in the first embodiment. On the other hand, when print data is received in step 804, carriage speed information is acquired in the subsequent step 805. The heater temperature information and the carriage speed information are matched, and in step 806, the cleaning frequency is set between recording scans for the face surface.

  The setting of the cleaning frequency between the recording scans is performed with reference to the table shown in FIG. FIG. 8B shows an example when the heater temperature is 40 ° C. Under the recording scanning time of 2 seconds (carriage speed: 25 inch / s), the cleaning is set to be performed once every 5 scans as shown in FIG. 8B. On the other hand, when the carriage speed is increased and the recording scanning time is shortened, the number of cleanings can be reduced as shown in FIG. For example, cleaning is performed once every 7 scans under a recording scan time of 1.4 seconds (carriage speed: 36 inch / s), and 10 times under a recording scan time of 1.0 second (carriage speed: 50 inch / s). It is set to perform cleaning once for scanning.

  When the cleaning frequency between the recording scans is set, the process proceeds to the next step 807 to start recording. Moreover, although a present Example shows the setting conditions in the heater temperature of 40 degreeC, it is not limited to this. In other words, the table shown in FIG. 8B is prepared for each heater temperature, similarly to the setting of the cleaning frequency between recording scans for the face surface for each heater temperature shown in the first embodiment. The cleaning frequency may be defined based on both the recording scan time and the recording scan time.

  The present invention is applicable to all devices using recording media such as paper, cloth, leather, non-woven fabric, OHP paper, and metal. Specific examples of applicable equipment include office equipment such as printers, copiers, and facsimiles using an ink jet recording method, and industrial production equipment.

DESCRIPTION OF SYMBOLS 1 Heating heater 9 Recording head 30 Cleaning mechanism 31 Wiping member 35 Cleaning mechanism control motor

Claims (4)

In an inkjet recording apparatus comprising: a recording head that is scanned along a recording medium and ejects ink; and a heating unit that heats the recording medium in an area scanned by the recording head.
A belt-like wiping member that is placed at a position opposite to the ejection port surface on which the ink ejection port of the recording head is formed and rubs against the ejection port surface; A cleaning mechanism that performs a wiping operation of the discharge port surface by moving the wiping member and the discharge port surface in contact with each other, the higher the heating temperature by the heating means, the higher the temperature of the discharge port surface by the cleaning mechanism. An ink jet recording apparatus characterized by increasing a cleaning frequency. The inkjet recording apparatus according to claim 1, wherein
The inkjet recording apparatus characterized in that the cleaning frequency of the discharge port surface by the cleaning mechanism is increased as the time during which the recording head scans the region where the heating unit is disposed is longer.   The inkjet recording apparatus according to claim 1, wherein a heating temperature by the heating unit is set according to a type of the recording medium.   4. The ink jet recording apparatus according to claim 1, wherein a scanning speed of the recording head is set in accordance with an image quality when the recording medium is recorded. 5.

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