JP2006007705A - Inkjet recorder and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to reduce the deterioration of image quality caused by the satellite and/or ink mist generated at discharging the ink from a recording head. <P>SOLUTION: The satellite and/or ink mist is made to be moved out of a recording area by blowing a wind with a blowing mechanism between the face surface of the recording head and a platen. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method using the ink jet recording apparatus, and more particularly to an ink jet recording apparatus having means for collecting satellites and mist generated when ink is ejected from a recording head, and a method thereof.

  In recent years, with the spread of the Internet, recording apparatuses having functions such as printers, copiers, and facsimiles are widely connected as output devices for composite electronic devices and workstations including computers and word processors in offices and general homes. . As the recording apparatus, an electrophotographic system, an inkjet system, a thermal system, and the like are widespread. Among them, the inkjet system is not only a paper, an OHP sheet, a film, but also a medium such as cloth, cardboard, earthenware, metal, etc. Can also be recorded. Furthermore, since printing is possible not only on flat media but also on uneven media, curved surfaces, and edges, it is widely used not only as a commonly used printer but also as a business printer. Note that an ink jet recording apparatus forms an image by ejecting liquid droplets from a nozzle using an electrothermal conversion element or an electromechanical conversion element.

  In particular, in an ink jet recording apparatus, the recording head can be easily downsized, the noise is low because it is a non-impact method, and it is easy to record a color image using multicolor ink. It has advantages such as low running cost and high-definition image recording at high speed. Furthermore, an ink jet recording head that ejects ink using thermal energy is subjected to a semiconductor manufacturing process such as etching deposition or sputtering, and the electrothermal transducer, electrode, liquid channel wall, ceiling, and the like formed on a substrate. By forming a plate or the like, a product having a high-density liquid passage arrangement (discharge outlet arrangement) can be manufactured, and further downsizing (miniaturization) can be achieved.

  In an ink jet recording apparatus, when ink droplets are ejected from a recording head, droplets smaller than the main droplet are ejected simultaneously with the main droplet. When a small droplet ejected simultaneously with the main droplet lands on the recording medium, dots having a size smaller than the main droplet are formed near the main droplet landed on the recording medium. Small droplets that are ejected at the same time as the main droplet, which are dots that land near the main droplet, are called satellites. Image quality deteriorates due to the landing of satellites at locations other than the main droplets. Further, mist-like ink droplets may be generated that are smaller than the ink droplets that become satellites. This mist-like ink droplet is called ink mist. The ink mist is caused to flow in the air current in the vicinity of the recording head when ink is ejected, and drifts in the apparatus, thereby causing the inside of the apparatus to become dirty or adhere to the recording medium, thereby degrading the image quality. When satellites or ink mist land on the recording medium, there are problems such as noise generated in the image and density unevenness and color change in the halftone image. In order to suppress degradation of image quality due to these satellites and ink mist, it is necessary to reduce the amount of satellites and ink mist carried outside the image area and attached to the recording medium.

As a method for reducing the adhesion of satellites and ink mist to the recording medium, a configuration has been devised in which negative pressure means for collecting and dispersing the satellites and ink mist is provided near the recording head and the recording medium (for example, Patent Documents 1 to 4). Japanese Patent Application Laid-Open No. 2004-228620 provides a means for generating an air pressure lower than the air pressure near the ink discharge port as the carriage moves at a position not facing the recording medium of the carriage, so that the carriage is lowered from the vicinity of the ink discharge port. A configuration is disclosed in which an air flow is generated to a place of atmospheric pressure, and satellites and ink mist floating between the recording head surface and the platen are caused to flow outside the image area. In Patent Document 2, a fan and a filter for sucking and collecting satellites and ink mist are provided on the carriage, and air is circulated in a direction parallel to the carriage by using the operation in the main scanning direction of the carriage. A configuration for collecting ink mist is disclosed. Patent Document 3 discloses a configuration in which a fan that blows air is provided between a recording medium and a discharge unit of a recording head in a carriage, and generated satellites and ink mist are dispersed in an unrecorded area by the fan. Further, Patent Document 4 discloses a configuration for controlling whether or not a fan provided in the vicinity of a recording head and a recording medium is driven according to the ink ejection speed.
JP 2001-113733 A Japanese Patent Laid-Open No. 07-025007 Japanese Patent Laid-Open No. 06-166173 Japanese Patent Laid-Open No. 11-348249

  However, in the configuration disclosed in Patent Document 1 described above, since negative pressure is generated as the carriage moves, satellites and ink mist floating between the recording head and the platen are removed when the carriage moving speed is slow. It is difficult to remove, and the image quality deteriorates due to satellites and ink mist that could not be removed. In addition, when the frequency of use of the recording apparatus increases, satellites and ink mist sucked out due to a pressure difference may adhere to the flow path of the means for generating negative pressure, and the function of generating negative pressure may be reduced. . The configuration disclosed in Patent Document 2 is effective in collecting the generated satellites and ink mists, but does not support bidirectional printing, so the recording speed decreases and the throughput decreases. In the configuration disclosed in Patent Document 3, satellites and ink mist are dispersed in unrecorded areas, so that the image quality of other recording areas is degraded. Further, in the configuration disclosed in Patent Document 4, whether or not to drive the fan is controlled according to the ink ejection speed. However, as a factor that satellites and ink mist are generated, in addition to the ink ejection speed, For example, if the recording duty is high even if the ink ejection speed is low, satellites and ink mist are generated, and the image quality is deteriorated. Furthermore, although the generation status of satellites and ink mist changes depending on the composition of the ink, the configuration disclosed in the above-mentioned patent document is not properly controlled by the ink composition.

  The present invention has been made based on the above viewpoint, and an object of the present invention is to use the wind speed or the air volume obtained from the wind feed mechanism provided in the carriage in the carriage moving direction between the recording head face surface and the platen. On the other hand, by flowing in the vertical direction, satellites and ink mist, which are main causes of image quality deterioration, are carried out of the image area. In particular, since the amount of satellites and ink mist generated varies depending on the ink composition mounted on the main body, it is necessary to flow a wind speed or air volume suitable for the mounted ink composition between the recording head face surface and the platen. In addition, by collecting satellites and ink mist by the collection means that collects the wind discharged from the wind feed mechanism, satellites and ink mist do not adhere to the outer wall and carriage peripheral members in the machine, and the frequency of use has increased. Even in this case, the function is not deteriorated, and a stable and high-quality image can be formed at high speed.

  The present invention relates to an ink jet recording apparatus that discharges a plurality of ink droplets from a discharge port of a recording head and performs recording during a reciprocating movement of the carriage. The air feed is sent to the carriage between a recording head face surface and a platen. A mechanism is provided, and the main body is provided with a detecting means for judging the ink composition, and the wind speed or the amount of air discharged from the wind feed mechanism is switched according to information obtained from the ink composition detecting means. And

  According to the present invention, since the collected satellite and ink mist are collected by the collecting means by the air discharged from the air blowing means controlled according to the situation where satellites and ink mist are generated, the outer wall and carriage peripheral member in the apparatus are collected. Satellites and ink mist do not adhere to the surface, and even when the frequency of use of the apparatus increases, the recovery function does not deteriorate, and a stable and high-quality image can be formed at high speed. In particular, since the amount of satellite and ink mist generated varies depending on the ink composition used for recording, the image quality is greatly improved by switching so that the control is suitable for the composition of the ink set in the main body. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a top view showing an ink jet recording apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 2 denotes an apparatus main body including a paper conveyance system unit. This apparatus performs recording on a relatively large recording sheet (recording medium). Reference numeral 1 denotes a carriage which is mounted and moved with twelve recording heads 5, whereby the recording head 5 can scan the recording paper. That is, the carriage 1 is guided and supported by the guide shaft 33 so as to be movable along the guide shaft 33, and can be reciprocated by a driving force transmitted through the belt 34. In addition to the cyan, magenta, yellow, and black inks used, a total of six colors including light cyan and light magenta for the purpose of reducing graininess are used, and the recording speed is improved. For this purpose, two recording heads are used for one color ink.

  Reference numerals 30A, 30B, 30C, and 30D denote a recovery mechanism that includes a cap and performs a suction operation using a pump (not shown) of each recording head 5 as a driving source, and protects the recording head when the recording head is not used. Reference numeral 31 denotes a preliminary ejection ink receiving box 32 that receives ink ejected by the preliminary ejection operation of each recording head 5, and indicates a wiping mechanism for performing a wiping operation of the ejection port surface of each recording head 5.

  In the above apparatus configuration, the carriage 1 moves in a direction (main scanning direction) along the guide shaft 33 in order to record on recording paper sent by a paper transport unit (not shown) when receiving recording data from the host device. Thus, each recording head 5 is scanned, and an image for one band is recorded on the recording paper. Then, the recording paper is transported by the paper transport unit for one band in the direction orthogonal to the carriage 1 (sub-scanning direction). An encoder film 35 for detecting the movement position of the carriage 1 is disposed along the movement path of the carriage 1, and an encoder sensor mounted on the carriage 1 knows the position of the carriage based on a signal for detecting this. be able to. The movement of the carriage 1 to the home position is controlled based on the position detection of the encoder.

  Each recording head 5 has 256 ejection openings arranged at a density of 600 dpi (dots / inch) in the sub-scanning direction, and ink is supplied into the ink liquid path communicating with each ejection opening. There is provided an electrothermal converter for locally heating to cause film boiling and ejecting ink by the pressure.

  FIG. 2 is a block diagram showing the configuration of the control system circuit in this embodiment. In this embodiment, reference numeral 300 denotes a main control unit. The main control unit 300 includes a CPU 301 that executes processing operations such as calculation, control, determination, and setting, and a ROM 302 that stores a control program to be executed by the CPU 301. A RAM 303 used as a recording data buffer, a work area for processing by the CPU 301, and an input / output port 304 are provided.

  The input / output port 304 is connected to the drive circuits 305, 306, 307, 308, and 309 such as the transport motor (LF motor) 312, the carriage motor (CR motor) 313, and the recording head 5. In addition, a head temperature sensor (head temperature detecting means) 314 that detects the temperature of the recording head, a home position sensor 310 that detects the home position of the carriage 1, and an ink composition detection sensor that detects the ink composition installed in the main body. Sensors such as 315 are connected. Further, the main controller 300 is connected to a host computer (not shown) via an interface circuit 311.

  When an ink tank is installed in the main body, the ink composition loaded by the ink composition detection sensor 315 is detected, and the obtained ink composition information is received and transferred to the CPU 301 of the main control unit 300 via the input / output port 304. After determining the ink composition mounted by the CPU 301, a control table suitable for the ink composition is sent to the drive circuit 308, and the discharge fan 7 mounted on the recording head 5 sends the optimum wind to the face surface 15 of the recording head 5. Send between platens 9. When the printing is completed, a signal is received from the input / output port 304, and the drive circuit 308 stops the discharge fan 7. Further, when the control related to printing enters the input / output port 304 from the main controller 300 and a signal is sent to each drive circuit, the drive circuit 309 of the recovery fan 12 mounted on the recovery means 10 controls the recovery fan 12 to control the recording head. The wind that has passed through the face surface 15 and the platen 9 is collected. When printing is completed, a signal is received from the input / output port 304, and the drive circuit 309 stops the recovery fan 12.

(Carriage configuration)
FIG. 3 is a perspective view of the carriage 1 including the wind feed mechanism 6 according to the embodiment of the present invention. The carriage 1 has a twin head configuration in which two recording heads 5 are mounted. A wind feed mechanism 6 provided in the carriage 1 is equipped with a discharge fan 7 for converting rotational energy into wind power, and is sent through a duct 8.

  Further, the wind feed mechanism 6 will be described in detail with reference to FIG. FIG. 4 is a cross-sectional view centering on the duct portion of the wind feed mechanism. The wind discharged from the wind feed mechanism 6 is sent between the face surface 15 of the recording head 5 and the platen 9 via the duct 8. The direction of the air sent is configured to be sent in a direction perpendicular to the moving direction of the carriage. Moreover, the wind speed sent is preferably 0.5 m / sec to 7 m / sec. Further, a control table for adjusting the wind speed or air volume of the wind discharged from the wind feed mechanism 6 is determined by the main control unit 300 based on the ink composition information sent from the ink composition detection sensor 315, and from the discharge fan 7. The output wind speed or air volume is controlled.

  The exhaust fan 7 used in the wind feed mechanism can function without any problem even with a sirocco fan as shown in FIG. 5 or an axial fan as shown in FIG. It is preferable to use a sirocco fan that can stably form a necessary wind speed, particularly when moving satellites or ink mists under a situation where the rotational speed of the discharge fan 7 is low.

  Thus, the wind sent from the wind feed mechanism 6 through the duct 8 between the face surface 15 of the recording head 5 and the platen 9 does not adversely affect the landing accuracy of the main droplets forming the image, and the image quality. Only satellites and ink mist, which are the main factors that reduce the image quality, can be blown out of the image area.

(Recovery means (1))
FIG. 7 is a cross-sectional view of the recovery means 10 for recovering the wind sent between the face surface 15 of the recording head 5 and the platen 9 from the wind feed mechanism 6 via the duct 8. Satellites and ink mist floating between the face surface 15 of the recording head 5 and the platen 9 are carried to the opening 11 of the collecting means 10 by the wind discharged from the wind feed mechanism 6. The recovery means 10 has a configuration that converts rotational energy and sucks wind, and the recovery fan 12 forms an airflow through which the wind flows in the direction of the arrow 14. Therefore, the satellite and ink mist carried to the opening 11 of the collecting means 10 are carried in the direction of the arrow 14 along the air flow of the collecting means 10 and collected by the filter 13 provided in the middle.

  The sirocco fan as shown in FIG. 5 and the axial fan as shown in FIG. It is preferable to use a sirocco fan that can stably form a necessary wind speed, particularly when collecting satellites and ink mist under a condition where the rotational speed of the recovery fan 12 is low.

  The present invention will be described in more detail with reference to the following examples, but the embodiment of the present invention is not limited thereto.

  The image evaluation method in the embodiment will be briefly described below.

In the image evaluation method, the duty ratio of an output image is varied from 10% to 100% and output, and the degree of occurrence of image unevenness due to mist or satellite is visually evaluated as follows.
Image unevenness ○: Good image quality without image unevenness ○ to Δ: Very little image unevenness is observed Δ: Slight image unevenness is observed ×: Image unevenness is observed over the entire image XX: Whole image Severe image unevenness is observed For image unevenness, it is difficult to observe whether or not there is unevenness in the image that is generally output on the market if it is an image of ○ level or ○ to Δ level or more. Level, and a satisfactory image can be output.

(Example conditions)
Carriage linear speed: 50 (inch / sec)
Carriage one-way travel distance: 36 (inch)
Image forming method: 1-pass reciprocating direction printing In Comparative Example 1, dye-based ink is used as an ink for forming an image, and the discharge fan 7 and the recovery fan 12 mounted on the carriage 1 are turned off. The number of passes at the time of image formation of the recording head 5 was varied and the image was output for evaluation. Table 1 shows evaluation results of image unevenness in Comparative Example 1.

  In the first pass and the second pass, the image unevenness is observed in four or more patches among ten gradation patterns, and in the third pass and the fourth pass, three of the ten gradation patterns. From Δ to x level where image unevenness is observed in one patch, and in 6 passes, Δ level where slight image unevenness is observed in 2 patches out of 10 gradation patterns. Among the 10 gradation patterns, the level is from ◯ to Δ where only one patch is observed with very little image unevenness.

  In Comparative Example 2, pigment-based ink is used as an ink for forming an image, and the power of the discharge fan 7 and the recovery fan 12 mounted on the carriage 1 is turned off. Images were output with variable number of passes and evaluated. Table 2 shows evaluation results of image unevenness in Comparative Example 2.

  In 1 pass, 2 passes, and 3 passes, image unevenness is observed in 4 or more patches among 10 gradation patterns, and in 4 passes, 3 of 10 gradation patterns. The Δ level indicates that image unevenness is observed in one patch, and the Δ level indicates that slight image unevenness is observed in two patches out of 10 gradation patterns during 6 passes and 8 passes.

  As can be seen from Comparative Example 1 and Comparative Example 2, in the configuration in which the wind is not sent between the face surface 15 of the recording head 5 and the platen 9 by driving the discharge fan, image unevenness occurs particularly when the number of passes is small. It occurs and is not at a practical level.

  Subsequently, in Example 1, a dye-based ink is used as an ink for forming an image, and the discharge fan 7 mounted on the carriage 1 is driven in a state where the power of the recovery fan 12 is turned off to perform recording. The number of passes at the time of image formation of the head 5 was varied and an image was output for evaluation. Table 3 shows the evaluation results of image unevenness in Example 1.

  In one pass and two passes, image unevenness is observed only slightly in one patch out of 10 gradation patterns, and from ◯ to △ level. In 3 passes or more, out of 10 gradation patterns, ○ level that is good image quality without image unevenness.

  As can be seen from the first embodiment, when dye-based ink is used, the level of image unevenness is improved by driving the discharge fan 7 in the range of 8 to 12 V, and an image of a practical level is output in all print modes. be able to.

  In the second embodiment, a pigment-based ink is used as an ink for forming an image, and the discharge fan 7 mounted on the carriage 1 is driven in a state in which the power of the recovery fan 12 is turned off, so that the recording head. The number of passes at the time of image formation of 5 was varied and the image was output for evaluation. Table 4 shows the evaluation results of image unevenness in Example 2.

  In one pass and two passes, image unevenness is observed only slightly in one patch out of 10 gradation patterns, and from ◯ to △ level. In 3 passes or more, out of 10 gradation patterns, ○ level that is good image quality without image unevenness.

  As can be seen from Example 2, when pigment-based ink is used, the level of image unevenness is improved by driving the discharge fan 7 in the range of 12 to 16 V, and an image of a practical level is output in all print modes. be able to.

  In addition, as apparent from Examples 1 and 2, since the proper driving conditions of the exhaust fan wind speed or air volume differ between the case of using dye-based ink and the case of using pigment-based ink, the composition of the ink is detected. Thus, it is effective to control the driving conditions suitable for each ink composition. Here, an example in which the driving condition of the pigment-based ink is higher than that of the dye-based ink is shown, but it is preferable to increase the driving condition of the dye-based ink depending on the ink composition, discharge conditions, and the like. Sometimes.

  Furthermore, not only switching between dye-based inks and pigment-based inks, but also solvent-based, semi-solvent-based, non-solvent-based or the same dye-based inks, acidic dyes, basic dyes, the same pigments, inorganic pigments, organic pigments, etc. Since the driving conditions of the discharge fan 7 differ depending on the difference, it is preferable to switch to driving conditions suitable for each.

  Further, in the third embodiment, dye-based ink is used as an ink for forming an image, and the discharge fan 7 mounted on the carriage 1 is driven in a state where the power of the recovery fan 12 is driven to perform recording. The number of passes at the time of image formation of the head 5 was varied and an image was output for evaluation. Table 5 shows the evaluation results of image unevenness in Example 3.

  Under the condition that the recovery fan 12 is driven, in all the printing modes, among the 10 gradation patterns, the ◯ level is a good image quality with no image unevenness.

  As can be seen from Example 3, when dye-based ink is used, the discharge fan 7 is driven in the range of 8 to 12 V, and the recovery fan 12 is driven to further improve the level of image unevenness. A practical level image can be output in the print mode.

  Finally, in Example 4, the pigment-based ink is used as the ink for forming an image, and the discharge fan 7 mounted on the carriage 1 is driven while the power supply of the recovery fan 12 is driven. The number of passes at the time of image formation of the recording head 5 was varied to output an image for evaluation. Table 6 shows the evaluation results of image unevenness in Example 4.

  Under the condition that the recovery fan 12 is driven, in all the printing modes, among the 10 gradation patterns, the ◯ level is a good image quality with no image unevenness.

  As can be seen from Example 4, when pigment-based ink is used, the discharge fan 7 is driven in the range of 12 to 16 V, and the recovery fan 12 is driven to further improve the level of image unevenness. A practical level image can be output in the print mode.

  As is clear from the description of Examples 1 to 4 and Comparative Examples 1 and 2, the ink jet recording apparatus having a recording head having a plurality of ink discharge ports uses ink of the same or different colors. The present invention can be similarly applied to a color recording device for recording, a gradation recording device for recording at different densities in the same color, and a combination of these, and achieves the same effect. It is possible. Furthermore, the present invention provides a recording means including a configuration using a replaceable ink jet cartridge in which the recording means and the ink tank are integrated, a configuration in which the recording means and the ink tank are separated and connected between them by a tube for supplying ink, etc. The present invention can be similarly applied to any arrangement of the ink tanks, and the same effect can be obtained.

  In addition, the present invention brings about an excellent effect in an ink jet recording apparatus that uses a recording unit that discharges ink using thermal energy, among other ink jet recording systems.

1 is a top view showing an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure of the control system circuit concerning embodiment of this invention. It is a perspective view of the carriage provided with the wind feed mechanism concerning embodiment of this invention. It is sectional drawing of the carriage provided with the wind feed mechanism concerning embodiment of this invention. It is a perspective view of the sirocco fan with which the wind feed mechanism concerning embodiment of this invention is equipped. It is a perspective view of the axial fan provided in the wind feed mechanism concerning embodiment of this invention. FIG. 6 is a cross-sectional view of a collecting unit that collects wind sent between the face surface of the recording head and the platen via a duct from the wind feeding mechanism.

Explanation of symbols

1 Carriage 2 Device body (including transport system unit)
DESCRIPTION OF SYMBOLS 5 Recording head 6 Air feed mechanism 7 Exhaust fan 8 Duct 9 Platen 10 Collection | recovery means 11 Opening part of collection | recovery means 12 Collection | recovery fan 13 Filter 14 Direction of wind flow of collection | recovery means 15 Recording head face surface 30A, 30B, 30C, 30D Recovery Mechanism 31 Preliminary discharge ink receiving box 32 Wiping mechanism 33 Guide shaft 34 Belt 35 Encoder film 300 Main control unit 301 CPU
302 ROM
303 RAM
304 I / O Port 305 LF Motor Drive Circuit 306 CR Motor Drive Circuit 307 Recording Head Drive Circuit 308 Ejection Fan Drive Circuit 309 Recovery Fan Drive Circuit 310 Home Position Sensor 311 Interface Circuit 312 LF Motor 313 CR Motor 314 Head Temperature Sensor 315 Ink composition detection sensor

Claims (8)

  In an ink jet recording apparatus that discharges a plurality of ink droplets from a discharge port of a recording head and performs recording when the carriage reciprocates, the carriage is provided with a wind feeding mechanism that sends air between the recording head face surface and the platen, Further, the main body is provided with detection means for determining the ink composition, and the air velocity or the air volume of the air discharged from the wind feed mechanism is switched according to information obtained from the ink composition detection means. apparatus.   In an ink jet recording apparatus that discharges a plurality of ink droplets from a discharge port of a recording head and performs recording during a reciprocating movement of a carriage, a detection means provided for determining an ink composition is based on information provided in the ink tank. The inkjet recording apparatus according to claim 1, wherein the determination is made.   3. The ink jet recording apparatus according to claim 1, wherein a wind direction discharged from the wind feed mechanism is a direction perpendicular to a moving direction of the carriage.   4. An ink jet recording apparatus according to claim 1, further comprising a collecting means for collecting the wind discharged from the wind feed mechanism.   The ink jet recording apparatus according to claim 1, wherein the means for generating wind discharged from the wind feed mechanism is a mechanism for converting rotational energy into wind power.   6. The ink jet recording according to claim 1, wherein the recording means is an ink jet recording means provided with an electrothermal converter that generates thermal energy used for ejecting ink. apparatus.   The ink jet recording apparatus according to claim 6, wherein the recording unit discharges ink from an discharge port using film boiling generated in the ink by heat energy applied by the electrothermal transducer.   8. An ink jet recording method for forming an image using an ink jet recording apparatus that discharges a plurality of ink droplets from a discharge port of a recording head and performs recording during a reciprocating movement of a carriage. An ink-jet recording method comprising forming an image using a recording apparatus.

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