JP2004090293A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small, inexpensive and highly reliable inkjet recorder in which cleaning operation of a recording head can be carried out smoothly and a stabilized image can be formed. <P>SOLUTION: The inkjet recorder comprises a recording head capable of ejecting ink, a section for containing ink being fed to the recording head, a carriage performing scanning in the main scanning direction while mounting the recording head, and a suction means for supplying ink from the ink containing section to the recording head and filling the recording head with ink. The recorder further comprises a cap closing means for covering the ink ejection plane of the recording head with a cap member when the suction means performs suction, a cap opening means for separating the cap member from the ink ejection plane of the recording head upon finishing suction, and a cap opening assist means for facilitating the cap opening operation when the cap means performs cap opening operation. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus that forms an image by forming ink dots on a recording medium.
[0002]
[Prior art]
The ink jet recording method is a recording method in which an image is formed by ejecting inks of a plurality of colors prepared for single color or color recording onto various recording media such as paper, cloth, nonwoven fabric, and plastic films for OHP. Is the way. An ink jet recording apparatus adopting this method includes a carriage on which a recording unit (recording head) and an ink tank serving as an ink storage unit are mounted and which is main-scanned in a predetermined direction with respect to the recording medium, and the recording medium is moved in the main scanning direction. Is provided with transport means for transporting (sub-scanning) in different directions, and control means for controlling these, so that the print head is serially scanned in the main scanning direction while a plurality of ink ejection ports provided in the print head are provided. Ink is ejected, and after the serial scan, the recording medium is conveyed by a predetermined amount (for example, the recording width in one serial scan corresponding to the ejection port arrangement range) to sequentially record on the recording medium. is there. In such an ink jet recording system, a so-called drop-on-demand system in which ink is directly ejected onto a recording medium in accordance with a recording signal to perform recording is adopted, and this provides an easy and inexpensive recording (recording) system. It has been widely adopted.
[0003]
By the way, an ink jet recording apparatus has an ink jet recording head having nozzles arranged at a pitch of 1/300 inch or 1/600 inch or the like. Is caused by evaporation of the recording liquid from the discharge port at the tip of the nozzle and accompanying increase in the viscosity of the recording liquid near the discharge port, which causes a defective discharge of the initial recording image when the next recording is started. . In other words, a missing dot, a displacement of a landing position of a recording liquid droplet on a recording medium, or the like occurs, and a recorded image may be unclear or erroneous.
[0004]
Conventionally, the following measures have been taken for such symptoms. That is, during standby of the ink jet recording head, the recording liquid from the ejection port is generally brought into contact with a surface on which the ejection port at the nozzle tip is arranged (hereinafter, referred to as an “ejection surface”) by a cap made of rubber. By providing a means (hereinafter referred to as “preliminary ejection”) for preventing evaporation of ink at the start of recording and for ejecting recording liquid irrelevant to recording at a location other than the recording section for a certain period of time at the start of recording, The recording liquid whose viscosity has been increased is discharged out of the ink jet recording head before recording or the like in order to suppress defects in the recorded image.
[0005]
Further, when the evaporation and the viscosity increase of the recording liquid further progress, the recording liquid is sucked from the ejection port through the cap, or the recording liquid is pressurized from the ink supply system to the ink jet recording head. Then, after the recording liquid in the nozzles is forcibly discharged, an operation of replacing the recording liquid with fresh recording liquid is performed (hereinafter, “recovery operation” by combining “suction” and “pressurization”), and then the recording operation is performed. Measures are also commonly taken.
[0006]
Further, the supply of the recording liquid to the recording head is generally such that a recording liquid storage container containing the recording liquid is installed in the apparatus, and the recording liquid is supplied to the recording head through a supply tube or the like. Therefore, after the recording liquid in one recording liquid storage container is completely used, the recording liquid is replaced with a new recording liquid storage container, and the recording liquid is continuously used. In order to fill the recording liquid in the supply path, the above-described recovery operation needs to be performed. Also, in the supply path, even when the recording liquid in the recording liquid storage container is being used, the recording liquid evaporates inside the recording liquid, and as a result, bubbles are generated and accumulated. Therefore, the necessity of the recovery operation arises also from this point. This becomes more pronounced as the length of the supply path increases and as the cross-sectional area decreases.
[0007]
On the other hand, in recent years, with the miniaturization of recording apparatuses, cartridge type ink jet recording heads in which a recording head section and a recording liquid storage container section are integrated have begun to spread. In such a case, the supply path from the recording liquid storage container to the recording head can be made short, so that the influence of bubbles in the supply path on the ejection failure can be reduced. Become. However, in a case where only the recording liquid storage container is exchangeable, the recovery operation for filling the supply path with the supply liquid is required at least once.
[0008]
FIG. 3 is a schematic cross-sectional view for explaining the operation of the cap at the time of suction recovery. FIG. 3A shows a state in which a cap 103 is brought into close contact with a discharge port surface 102 of a recording head 101, and a suction pump (not shown) connected to the cap 103 generates a negative pressure to suck ink from the discharge ports. Thereafter, a capping state when the negative pressure is almost eliminated (capping state when the negative pressure is reduced to such an extent that the meniscus of the discharge port is not broken) is shown. Note that the hatched portion 104 in FIG. 3 indicates the ink that has been sucked out. In the state of FIG. 3A, it is considered that the inside of the cap 103 is almost completely filled with ink.
[0009]
When the cap 103 is to be separated from the capping state of FIG. 3A, as shown in FIG. 3B, at the interface between the discharge port surface 102 and the ink 104, the adhesive force of the ink and the negative pressure in the discharge port are reduced. As a result, a force acting to suck up the ink acts, and furthermore, a surface tension that causes the ink itself to agglomerate acts on the ink in the cap 103, so that a neck 105 occurs between the inks 104. As the cap 103 moves away, the cross-sectional area of each constriction 105 of the ink 104 becomes smaller and weakest, and finally the connection between the inks is cut off at each constriction 105.
[0010]
FIG. 3C shows a state after the ink has run out at each of the constrictions 105. After the ink runs out, a part of the ink remains on the discharge port surface 102 as shown. At this time, the amount of ink remaining on the ejection port surface 102 is larger than the amount of ink attached due to mist or the like during recording, and tends to increase as the surface tension of the ink decreases and the water repellency of the ejection port surface 102 decreases. There is. The greater the amount of ink adhered to the discharge port surface 102, the greater the load on the wiping blade and wiper cleaner, and the shorter their life. In addition, in the example shown in FIG. 3, since ink remains in the cap 103 when the cap 103 is separated, dripping or scattering of the ink also becomes a problem.
[0011]
Further, if the cap 103 is separated immediately after suction of the ink, the atmospheric pressure is instantaneously applied to the inside of the cap where the negative pressure remains, and the meniscus in the discharge port is destroyed due to the sudden pressure fluctuation at this time and the mechanical shock at the time of separation. In some cases, air may penetrate deep into the ejection openings, causing ink ejection failure.
[0012]
Due to such a phenomenon, an air communication valve may be provided in the cap in order to suppress the amount of ink remaining on the ejection port surface after ink suction and to suppress instantaneous atmospheric pressure in the cap. An atmosphere communication valve is provided with a path that can take in air separately from the path that generates negative pressure in the cap, and can take in the negative pressure generated in the cap while the recording head and the cap are in close contact with each other. Since it is possible, it is possible to suppress the amount of ink remaining on the ejection port surface after ink suction, and it is possible to suppress instantaneous atmospheric pressure from being applied to the inside of the cap.
[0013]
[Problems to be solved by the invention]
However, such an ink jet recording apparatus has the following problems to be solved.
[0014]
In order to solve the above-mentioned problems, according to Japanese Patent Application Laid-Open No. 2001-58421, an ink jet recording apparatus without an air communication valve is stopped until the negative pressure generated in the cap after ink suction is completely reduced. However, in this case, a mixture of inks of a plurality of colors stays in the cap for a long time, and may flow back to the recording head. If the image is recorded as it is, there is a high possibility that an image problem such as a mixed color in which the original color is mixed with another color will occur. Further, if the cap is stopped until the negative pressure generated in the cap after ink suction is completely relieved and the cap is opened, useless ink discharged by suction increases, resulting in a problem that the running cost is reduced.
[0015]
In addition, recent inkjet recording apparatuses tend to be miniaturized, and accordingly, it is necessary to miniaturize the cap and its peripheral mechanism. For this reason, it has become difficult to provide the above-described atmosphere communication valve on the small cap or to arrange a mechanism for operating the atmosphere communication valve. Further, there is a case where dust is clogged in a tube used for connection with the atmosphere communication valve and the tube does not function. In addition, the atmosphere communication valve requires a dedicated drive source or needs to be driven from another drive source, which causes a problem that the apparatus becomes complicated and costs increase.
[0016]
SUMMARY OF THE INVENTION The present invention has been made in view of the above as a problem to be solved, and it is an object of the present invention to provide a small, inexpensive and highly reliable ink jet recording apparatus which smoothly performs a cleaning operation of a recording head and forms a stable image. With the goal.
[0017]
[Means for Solving the Problems]
In order to solve the above-described problems, an ink jet recording apparatus according to the present invention is provided with a recording head capable of discharging ink, a carriage for scanning in a main scanning direction, and a device for sucking ink from the recording head. A suction unit and a cap member that covers the ink ejection surface of the recording head with a cap member during suction by the suction unit, and a cap opening operation that separates the cap member from the ink ejection surface of the recording head is performed after the suction is completed. It is characterized by comprising a cap means and a cap opening auxiliary means for performing a cap opening auxiliary operation for facilitating the cap opening operation when the cap opening operation is performed by the cap means.
[0018]
Further, the inkjet recording apparatus of the present invention is provided with a recording head capable of discharging ink, a carriage for scanning in a main scanning direction, a suction unit for sucking ink from the recording head, and a suction unit. A cap means for performing a cap closing operation for covering the ink ejection surface of the recording head with the cap member at the time of suction, and performing a cap opening operation for separating the cap member from the ink ejection surface of the recording head after completion of the suction; A cap opening operation detecting means for detecting whether or not the cap opening operation can be performed; and a cap opening operation for facilitating the cap opening operation when the cap opening operation detecting means detects that the cap opening operation cannot be performed. And a cap opening assisting means for performing an assisting operation.
[0019]
Here, the cap opening / closing operation by the cap means can be performed by moving the carriage in the main scanning direction.
[0020]
Further, the cap opening operation detecting means can detect whether the carriage is movable by a predetermined amount.
[0021]
Further, the cap opening operation detecting means may include a means for detecting an amount of movement of the carriage per unit time by an encoder for detecting a position of the carriage.
[0022]
Further, the cap opening operation detecting means may include a means for detecting a current value per unit time flowing to a drive source for driving the carriage.
[0023]
Further, the cap opening operation detecting means may include a means for detecting whether a current value per unit time flowing to a drive source for driving the carriage is equal to or more than a predetermined value and has continued for a predetermined time.
[0024]
Here, the cap opening assisting means may include means for stopping the cap member with respect to the recording head for a predetermined time.
[0025]
Further, the cap opening assisting means may include means for slightly reciprocating the carriage in the main scanning direction.
[0026]
Further, the cap opening assisting means may include means for generating a predetermined positive pressure for a predetermined time in the cap member.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
(Example 1)
FIG. 1 is a perspective view showing a schematic configuration of a recording apparatus having a recording head for performing recording according to an ink jet system, which is a typical embodiment of the present invention.
[0028]
In FIG. 1, reference numeral C denotes an ink jet cartridge (hereinafter, referred to as an ink cartridge) having an ink tank as an ink storage section above, a recording head below the ink tank, and a connector for receiving a signal for driving the recording head and the like. And a carriage 2 on which a plurality of cartridges C are mounted. The ink tanks of the respective cartridges C contain inks of different colors such as yellow, magenta, cyan, and black inks. Further, the carriage 2 is provided with a connector holder for transmitting a signal for driving the recording head of each cartridge C and the like, and is electrically connected to the recording head. In the example shown in FIG. 1, four cartridges C containing yellow, magenta, cyan, and black inks in respective ink tanks from the left are mounted.
[0029]
Reference numeral 11 denotes a scanning rail that extends in the direction in which the recording head scans (main scanning direction) and slidably supports the carriage 2; 52, a carriage motor; and 53, a carriage for reciprocating the carriage 2 in the main scanning direction. Drive belts 5 and 6, and 7 and 8 for transmitting the driving force of the motor 52 are disposed before and after the recording position of the recording medium by the recording head, and are a pair of transport rollers for nipping and transporting the recording medium. Recording medium. The recording medium P is pressed against a guide surface of a platen (not shown) for regulating the recording surface flat.
[0030]
The recording head of the cartridge C mounted on the carriage 2 projects downward from the carriage 2 and is located between the conveying rollers 6 and 8, and the ejection port forming surface on which the ejection port of the recording head is formed is And a recording medium P pressed against a guide surface of a platen (not shown) in parallel.
[0031]
Now, in the recording apparatus of this embodiment, a recovery system unit is disposed, for example, on the home position side on the left side in FIG.
[0032]
In FIG. 1, regarding this recovery system unit, reference numeral 300 denotes a vertically movable cap unit provided corresponding to each of the recording heads provided in each of the four cartridges C. When the carriage 2 is at the home position, the cap unit 300 as a cap unit is joined to the recording head and caps the recording head, preventing the ink in the ejection openings of the recording head from evaporating, and increasing the viscosity of the ink. Or, it is possible to prevent the volatile components from evaporating and sticking to cause ejection failure.
[0033]
Further, the inside of the cap unit 300 is communicated with a pump unit (not shown) as suction means. The pump unit creates a negative pressure as needed. The timing at which the negative pressure is generated is, for example, in the event that the recording head has an ejection failure, when the suction recovery is performed by joining the cap unit 300 and the recording head, or when the ink preliminarily ejected into the cap of the cap unit 300 is used. For example, when empty suction is performed.
[0034]
Reference numeral 401 denotes a preliminary ejection receiving unit provided on the opposite side of the home position with respect to the recording operation area for the recording medium P. The preliminary ejection receiving unit 401 performs preliminary ejection of the recording head. Further, the recovery system unit may be provided with a blade formed of an elastic member such as rubber so as to wipe liquid droplets attached to the ejection port forming surface of the recording head.
[0035]
In the printing apparatus of this embodiment, the drive motor for feeding the print medium P and the drive motor for operating the recovery system unit are the same and are shared.
[0036]
FIG. 2 is a perspective view of the ink jet cartridge C in which the recording head and the ink tank are integrated.
[0037]
As shown in FIG. 2, the cartridge C has an ink tank T at the upper side and a recording head 86 at the lower side. A head-side connector 85 is provided at the position. The connector 85 receives a signal for driving the recording head 86 and the like and outputs an ink remaining amount detection signal. The recording head 86 is formed with an ejection port surface 1 having a plurality of ejection ports that are open on the bottom side in the lower part of the figure, and is necessary for ejecting ink to a liquid path portion communicating with each ejection port. An electrothermal converter that generates the heat energy to be applied is disposed.
[0038]
FIG. 4 is a schematic diagram of the carriage operation and the cap opening / closing operation at the time of suction of the inkjet printer in which the opening and closing operation of the cap 12 is performed by moving the carriage 2 on which the recording head 101 is mounted in the main scanning direction.
[0039]
Normally, when the recording head 101 performs a recording operation, the cap 12 as the cap means is retracted to a position away from the carriage 2 as shown in FIG.
[0040]
At the time of suction, as shown in FIG. 4B, the carriage 2 moves to the right, the cap 12 comes into contact with the recording head mounted on the carriage, and a negative pressure is generated in the cap by a pump connected to the cap. The ink is sucked in the direction of the arrow shown in FIG. 4B to fill the recording head with the ink.
[0041]
After the suction, as shown in FIG. 4C, the carriage 2 is further moved to the right so that the cap is pushed down in a direction away from the recording head, and the air is taken into the cap and the ink accumulated in the cap is sucked. .
[0042]
Here, one embodiment of the cap means for realizing the opening and closing operation as described above is shown in FIG.
[0043]
As shown in FIG. 5A, the cap member 12 is rotatably attached to a support member 14 via an elastic member 13 such as a spring. A lower fulcrum 14a of the support member 14 The top of the track is connected to an L-shaped guide member 15 extending therefrom. Further, the cap member 12 has a convex portion 20 having a slope 21 near the upper portion of the support member 14, and the lower fulcrum 14a of the support member 14 is provided with a track groove 18 provided on a fixed member attached to the exterior of the recording apparatus. Along with the cap member 12 and the guide member 15.
[0044]
In this embodiment, at the time of suction, as shown in FIG. 5B, the carriage 2 moves to the right and abuts on the guide member 15, whereby the cap member 12 rises along the track groove 18. , Cap closing operation position P _B Then, the cap member 12 and the ink ejection port surface of the recording head 101 mounted on the carriage 2 come into contact with each other, and a cap closing operation for covering the ink ejection port surface is performed.
[0045]
After the suction is completed, the carriage 2 further moves rightward as shown in FIG. _C At this time, the fixed protrusion 25 attached to the exterior of the recording apparatus comes into contact with the protrusion 20 of the cap member 12, and the cap member 12 is supported by the fixed protrusion 25 riding on the slope 21 of the protrusion 20. The cap is rotated around the upper portion of the member 14 to separate the cap from the ink ejection port surface.
[0046]
In the cap member configured as described above, the cap is opened and closed by moving the carriage in the main scanning direction. Therefore, when the cap is separated from the recording head after suction as described above, the negative When the pressure is high, the contact force with the recording head due to the negative pressure generated in the cap may be larger than the moving force of the carriage. For this reason, the carriage cannot move and a carriage error may occur. Also, even if the cap can be accidentally separated from the recording head, atmospheric pressure will be instantaneously applied to the cap where negative pressure remains. In some cases, the meniscus is destroyed, and air enters deep inside the ejection port, causing ink ejection failure.
[0047]
Also, if the cap is to be separated from the print head in a state where the negative pressure in the cap has returned to zero (atmospheric pressure), the discharge port of the print head will come into contact with the mixed ink of a plurality of colors accumulated in the cap. For a long time, the ink may flow backward to the recording head. If the image is recorded as it is, there is a high possibility that an image problem such as a mixed color in which the original color is mixed with another color will occur.
[0048]
FIG. 6 is a table summarizing a carriage error that occurs when the cap is separated from the recording head immediately after suction (when the negative pressure in the cap is high) and the frequency of occurrence of ejection failure due to air entering the ejection port. is there.
[0049]
A suction operation was performed, and in order to confirm whether normal ejection was performed after the suction and an image could be recorded, a pattern for checking the ejection was repeatedly printed by printing one pattern for each suction operation. When the above procedure was confirmed 50 times, a carriage error occurred 11 times, and 5 out of 50 images of ejection failure due to air entering the ejection port were output. When the operation was continued up to 100 times, the carriage error was output 25 times, and nine images of ejection failure were output.
[0050]
FIG. 7 summarizes the frequency of occurrence of color mixing that occurs when the carriage is stopped until the negative pressure in the cap is eliminated after suction and the cap is separated (when the negative pressure in the cap is zero). .
[0051]
A suction operation was performed, and in order to confirm whether normal ejection was performed after the suction and an image could be recorded, a pattern for checking the ejection was repeatedly printed by printing one pattern for each suction operation. As a result of checking 50 times in the above procedure, 7 out of 50 mixed images and 12 out of 100 images were output. That is, if the cap opening operation is performed with the high negative pressure generated in the cap at the time of suction or the cap opening operation is performed after the generated negative pressure is reduced to the atmospheric pressure, various problems and image problems are caused.
[0052]
FIG. 8 is a graph showing a time variation of a negative pressure generated in the cap at the time of suction when the suction operation of the present invention is performed.
[0053]
The vertical axis in FIG. 8 represents the negative pressure [kpa] in the cap, and the horizontal axis represents the elapsed time [sec] from the start of suction.
[0054]
A solid line {circle around (1)} in FIG. 8 is a negative pressure curve in a case where the carriage is stopped until the negative pressure in the cap generated after the suction is completely reduced. As described with reference to FIG. 7, in this ink jet printer, when the carriage is stopped until the negative pressure in the cap is completely relaxed and then the cap opening operation is performed, the ink accumulated in the ejection port and the cap becomes about 10%. For 0.0 seconds, color mixing is likely to occur.
[0055]
A solid line {circle around (3)} in FIG. 8 is a negative pressure curve when the cap opening operation is performed in a state where the negative pressure in the cap generated after the suction is the highest. As described with reference to FIG. 6, in this ink-jet printer, the adhesion force with the recording head due to the negative pressure generated in the cap becomes larger than the moving force of the carriage, so that the carriage cannot move and a carriage error occurs, Even if the head can be accidentally released from the recording head, a negative pressure remains, and the atmospheric pressure is instantaneously applied to the cap, and the meniscus in the discharge port is destroyed by the sudden pressure fluctuation at this time and the mechanical shock at the time of separation. In some cases, air may penetrate deep into the ejection openings, causing ink ejection failure.
[0056]
The solid line (2) in FIG. 8 indicates that the carriage is stopped at the suction position from about 4.5 seconds to about 6.0 seconds (ie, until the negative pressure in the cap reaches between Pa and Pb) from the start of suction. It is a negative pressure curve in the case of performing a cap opening assisting operation of performing the opening operation.
[0057]
Pa is the lower limit of the negative pressure at the time of performing the cap opening operation without causing a carriage error, which is obtained from an experiment, and without causing air to enter deep into the ejection port to cause ink ejection failure. Pb is the upper limit of the negative pressure at the time of performing the cap opening operation without color mixing, which is obtained from an experiment.
[0058]
Since the above-mentioned negative pressure curve has reproducibility, even if the negative pressure detecting means in the cap is not provided, the carriage can be stopped at the suction position for a predetermined time after the start of suction, so that the negative pressure in the cap can be easily reduced. The pressure can be kept within a predetermined negative pressure range.
[0059]
FIG. 9 is a table summarizing the carriage error, the ejection failure caused by air entering the ejection port, and the frequency of occurrence of color mixing when the suction operation for drawing the negative pressure curve described with reference to FIG. 8 is performed.
[0060]
The suction operation is performed in the same manner as in FIGS. 6 and 7, and a pattern for checking the discharge to confirm whether the normal discharge is performed after the suction and the image can be recorded is set to one every one suction operation. Printing of the pattern was repeated. As shown in FIG. 9, the above examination was repeated 100 times. As a result, no problems such as a carriage error, a discharge failure due to air entering into the discharge port, color mixing, and an image defect were found.
[0061]
The solid line of (2) in FIG. 8 uses the stop of the carriage after suction as the cap opening assisting operation, but other cap opening assisting operations may be used.
[0062]
For example, in the main scanning direction at a suction position from a predetermined point in time, the negative pressure in the cap after stopping the suction pump (after Pmax in FIG. 8) reaches between Pa and Pb, which is experimentally obtained in advance. A predetermined number of reciprocating movements of the carriage along the axis may be used.
[0063]
Similarly, a predetermined time period from the predetermined point in time by the pump from the predetermined point in time after which the negative pressure in the cap after stopping the suction pump (after Pmax in FIG. 8) reaches between Pa and Pb, which was previously experimentally obtained. A cap opening assisting operation such as a pressing operation of a predetermined pressure in the positive pressure direction may be performed.
[0064]
Thus, even if the cap opening operation is performed after the negative pressure in the cap after suction reaches between Pa and Pb, the same effect as (2) in FIG. 8 can be obtained. In addition, the cap opening assisting operation is performed by combining the operations of stopping the carriage, the minute reciprocating operation of the carriage at the suction position, and the operation of generating the pressure in the positive pressure direction from the pump as described above. Even if the cap opening operation is performed after the pressure reaches between Pa and Pb, the same effect as (2) in FIG. 8 can be obtained.
[0065]
As described above, after the ink is filled and supplied to the recording head by the suction means, when the cap performs the cap opening operation on the recording head, the cap opening assist means for easily performing the opening operation of the cap means is performed. For example, since a stable suction operation can be performed, it is possible to provide a highly reliable inkjet printer that does not cause ejection failure or the like.
[0066]
(Example 2)
In the second embodiment, it is detected whether or not the cap opening operation can be performed by the movement of the carriage in the main scanning direction during the suction operation in the inkjet printer that opens and closes the cap. A cap opening assisting operation for facilitating the opening operation of the cap is performed.
[0067]
As in the first embodiment, the operations of the recording head and the cap at the time of suction in the carriage main scanning direction are the same as those in FIG. 4A. At the time of suction, the suction operation is performed in the state of FIG. 4B. When the air is taken into the cap after the suction and the ink accumulated in the cap is sucked, the operation is performed as shown in FIG. Here, when shifting from FIG. 4B to FIG. 4C, in the first embodiment, the cap opening assisting operation for uniformly reducing the negative pressure generated in the cap in all the suction operations is performed. Has a configuration in which a cap opening operation detecting means for detecting whether or not the cap opening operation can be performed is used to perform a cap opening assisting operation when it is detected that the cap opening operation cannot be performed.
[0068]
FIG. 10 shows a sequence during a suction operation of the ink jet printer having the features of the second embodiment.
[0069]
Hereinafter, description will be given according to the flowchart of FIG. 10 with reference to FIG.
[0070]
First, the inkjet printer receives a command to execute a suction operation, and in S1, a cap closing operation position P at which the carriage contacts the cap. _B Move to
[0071]
In S2, a negative pressure is generated in the cap by the operation of the pump mechanism connected to the cap, and a suction operation is performed to fill the recording head with ink.
[0072]
In S3, an instruction to move the carriage to the cap opening operation position Pc for performing the cap opening operation is issued.
[0073]
In S4, the encoder that detects the movement of the carriage as the cap opening operation detecting means detects whether the carriage has been moved to the position Pc where the cap opening operation is performed according to the instruction in S3.
[0074]
In S5, if the cap opening operation cannot be performed in S4, it is further determined whether the load current flowing to the motor for moving the carriage in the main scanning direction at that time is equal to or more than a predetermined value, and whether a predetermined time has elapsed in that state. Detect.
[0075]
In S6, when the condition in S5 is not satisfied, the carriage 2 is stopped at the suction position for 0.5 sec in order to reduce the negative pressure generated in the cap 12. After the carriage 2 stops, the process returns to the step S3 to instruct the carriage to move to the position Pc where the cap opening operation is performed.
[0076]
In S7, when the condition in S5 is satisfied (when it is assumed that the negative pressure in the cap 12 has become higher than the step in S6), the carriage 2 is slightly reciprocated in the main scanning direction around the suction position. . The number of reciprocating operations can be determined as appropriate, for example, by experimentally obtaining it in advance. Since this operation applies a force in a direction in which the cap 12 is in close contact with the recording head 101 and applies an external force to the recording head to separate the cap from the recording head 101, the carriage 2 is stopped to reduce the negative pressure, which is a shorter time. This makes it possible to relieve the negative pressure. After performing the minute reciprocating operation of the carriage 2, the process returns to the step S3 again, and an instruction to move the carriage 2 to the position Pc at which the cap opening operation is performed is performed.
[0077]
In S8, the encoder detects in S4 whether or not the carriage has been moved to the position Pc for performing the cap opening operation in accordance with the instruction in S3, and if the cap opening operation can be performed, the cap remains in the cap after the opening operation. Perform idle suction of the ink.
[0078]
In S9, preliminary ejection after suction is performed.
[0079]
In S10, wiping after suction is performed.
[0080]
In S11, preliminary ejection after wiping is performed, and in S12, the carriage is moved to a print standby position.
[0081]
In order to detect whether or not the cap opening operation can be performed in the flowchart of FIG. 10, a predetermined amount of movement of the carriage, a predetermined current value flowing through the motor that operates the carriage, and a duration of the predetermined current value are determined. Although the cap opening operation detecting means is combined with the cap opening operation detecting means, each element may be used alone as the cap opening operation detecting means to detect whether or not the cap opening operation can be performed.
[0082]
In the flowchart of FIG. 10, as a result of detecting whether or not the cap opening operation can be performed, when the cap opening operation cannot be performed, the carriage stop and the carriage minute reciprocating operation are respectively selected as cap opening assisting means. However, similarly to the first embodiment, a cap opening assisting means such as stopping of the carriage, minute reciprocating operation of the carriage, and generating pressure in the positive pressure direction from the pump may be combined.
[0083]
FIG. 11 is a table summarizing a carriage error when the cap is opened after suction, a discharge failure due to air entering the discharge port, and a frequency of occurrence of color mixing in the ink jet printer implementing the sequence described in FIG. .
[0084]
A suction operation is performed based on the sequence in FIG. 10, and a pattern for checking the discharge is printed for each suction operation in order to check whether a normal discharge is performed after suction and an image can be recorded. This was repeated. As shown in FIG. 11, the above examination was repeated 100 times. As a result, there were no problems such as a carriage error, a discharge failure due to air entering the discharge port, a color mixture, and an image problem.
[0085]
In the ink jet printer which performs opening and closing operations of the cap by moving the carriage in the main scanning direction as described above, after the ink is filled and supplied to the recording head by the suction means, the cap performs the cap opening operation on the recording head. If it is detected whether or not the cap opening operation can be performed, and if it is detected that the cap opening operation cannot be performed, the cap opening auxiliary means for easily performing the opening operation of the cap means can be performed, the more efficient Since a stable suction operation can be performed, it is possible to provide a highly reliable ink jet printer which does not cause ejection failure or the like.
[0086]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a small, inexpensive, and highly reliable inkjet recording apparatus that smoothly performs a suction operation of a recording head and outputs a stable image.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of an ink jet recording apparatus to which the present invention can be applied.
FIG. 2 is a perspective view of an ink jet cartridge used in the ink jet recording apparatus of FIG.
FIG. 3 is a schematic partial cross-sectional view for explaining a suction recovery operation in a conventional ink jet recording apparatus in which a cap is detached in parallel with movement of a carriage.
FIG. 4 is a schematic partial cross-sectional view for explaining a suction recovery operation in an ink jet recording apparatus to which the present invention is applied, in which a cap is separated obliquely with respect to movement of a carriage.
FIG. 5 is a schematic view showing an embodiment of the cap means of the present invention.
FIG. 6 is a table summarizing a carriage error that occurs when the cap is separated from the recording head immediately after suction, and a frequency of occurrence of ejection failure due to air entering the ejection port.
FIG. 7 is a table summarizing the frequency of occurrence of color mixing that occurs when the carriage is stopped until the negative pressure in the cap is eliminated after suction and then the cap is separated.
FIG. 8 is a diagram showing a time variation of a negative pressure generated in the cap at the time of suction when the suction operation of the present invention is performed.
9 is a table summarizing a carriage error, a discharge failure due to air entering into a discharge port, and a frequency of occurrence of color mixing when performing a suction operation for drawing a negative pressure curve described with reference to FIG. 8;
FIG. 10 is a diagram illustrating a sequence at the time of a suction operation of an inkjet printer in which features of the second embodiment are mounted.
11 is a table summarizing a carriage error when a cap is opened after suction, a discharge failure due to air entering into a discharge port, and a frequency of occurrence of color mixing in an ink jet printer implementing the sequence described in FIG. .
[Explanation of symbols]
1 Discharge port surface
2 carriage
5 Transport rollers
6 Transport rollers
7 Transport rollers
8 Transport rollers
11 scanning rail
12 Cap member
13 Elastic member
14 Supporting members
14a Lower fulcrum
15 Guide member
18 Track groove
20 convex
21 Slope
25 fixed convex
52 Carriage motor
84 air hole
85 Head side connector
86 recording head
101 Recording head
102 Discharge port surface
103 cap
104 ink
105 Constriction
300 cap unit
C cartridge
P Recording medium
T ink tank
P _A Cap standby position
P _B Cap closing operation position
P _C Cap opening operation position

Claims (12)

A carriage mounted with a recording head capable of ejecting ink and scanning in the main scanning direction;
Suction means for sucking ink from the recording head;
Cap means for performing a cap closing operation of covering the ink ejection surface of the recording head with a cap member at the time of suction by the suction means, and performing a cap opening operation of separating the cap member from the ink ejection surface of the recording head after completion of suction;
An ink jet recording apparatus comprising: a cap opening assisting means for performing a cap opening assisting operation for facilitating the cap opening operation when the cap opening operation is performed by the cap means. A carriage mounted with a recording head capable of ejecting ink and scanning in the main scanning direction;
Suction means for sucking ink from the recording head;
Cap means for performing a cap closing operation of covering the ink ejection surface of the recording head with a cap member at the time of suction by the suction means, and performing a cap opening operation of separating the cap member from the ink ejection surface of the recording head after completion of suction;
Cap opening operation detecting means for detecting whether the cap opening operation by the cap means can be performed,
An ink jet recording apparatus comprising: a cap opening assisting unit that performs a cap opening assisting operation that facilitates the cap opening operation when the cap opening operation detecting unit detects that the cap opening operation cannot be performed. apparatus. The inkjet recording apparatus according to claim 1, wherein the cap opening / closing operation by the cap unit is performed by moving the carriage in a main scanning direction. 3. The ink jet recording apparatus according to claim 2, wherein the cap opening operation detecting means detects whether the carriage is movable by a predetermined amount. 5. The ink jet recording apparatus according to claim 4, wherein said cap opening operation detecting means includes means for detecting an amount of movement of the carriage per unit time by an encoder for detecting a position of the carriage. 6. The ink jet recording apparatus according to claim 4, wherein the cap opening operation detecting unit includes a unit for detecting a current value per unit time flowing to a driving source for driving the carriage. 5. The apparatus according to claim 4, wherein the cap opening operation detecting means includes means for detecting whether a current value per unit time flowing to a drive source for driving the carriage is equal to or more than a predetermined value and has continued for a predetermined time. 7. The ink jet recording apparatus according to any one of items 1 to 6. 8. An ink jet recording apparatus according to claim 1, wherein said cap opening assisting means includes means for stopping said cap member with respect to said recording head for a predetermined time. 9. The ink jet recording apparatus according to claim 8, wherein the cap opening assisting means includes means for slightly reciprocating the carriage in the main scanning direction. 10. The ink jet recording apparatus according to claim 8, wherein the cap opening assisting means includes a means for generating a predetermined positive pressure for a predetermined time in the cap member. The cap opening assisting means includes an opening assisting means for stopping the cap member with respect to the recording head for a predetermined time, an opening assisting means for slightly reciprocating the carriage in the main scanning direction, and a predetermined time in the cap member. The ink jet recording apparatus according to any one of claims 1 to 10, further comprising a combination of opening assist means for generating a predetermined positive pressure. The cap opening operation detecting means detects a current value per unit time flowing to a driving source for driving the carriage, and the current value per unit time flowing to the driving source for driving the carriage is equal to or more than a predetermined value. Detecting means for detecting whether or not a predetermined time has elapsed, and detecting means for detecting an amount of movement of the carriage per unit time by an encoder for detecting the position of the carriage. Item 3. An ink jet recording apparatus according to item 2.

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