JPH0890796A - Ink jet recording device - Google Patents

Abstract

(57) [Abstract] [Purpose] Efficiently eliminates color mixture after suction when an inkjet head of the liquid chamber separation type that can discharge multiple colors in the same head is used, and waste ink is not wasted. Perform stable and high-quality recording. [Structure] When the button for head recovery is pressed, the negative pressure of each of the ink tanks of four colors A to D is detected as START (step S71). Next, the negative pressure difference from the ink tank having the minimum negative pressure is obtained (step S72). Then, the number of preliminary ejections required for each of the minimum negative pressure of one color and the remaining three colors is selected (step S73). After that, suction (step S74) and wiping (step S75) are performed, the number of preliminary ejections selected in step S73 is performed for each of the four colors (step S76), and the print standby state is set to END. In this way, the color mixture that occurs after suction is eliminated by the number of preliminary ejections suitable for the ink ejection rows of each color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for recording by ejecting ink from a recording means to a recording material.

[0002]

2. Description of the Related Art A recording device having functions such as a printer, a copying machine, and a facsimile, or a recording device used as an output device such as a composite electronic device including a computer and a word processor, a workstation, etc. The image (including characters and the like) is recorded on a recording material (recording medium) such as a sheet of paper or a plastic thin plate. The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type, etc., depending on the recording method.

Among the above recording apparatuses, an ink jet type recording apparatus (hereinafter referred to as "ink jet recording apparatus")
Is a recording unit (hereinafter, referred to as a "recording head") that ejects ink onto a recording material to perform recording. The recording head can be easily made compact, and high-definition images can be recorded at high speed. It is possible to record on plain paper without requiring special processing, low running cost, less noise due to non-impact method, and moreover, color images are recorded using multicolor inks. It has advantages such as being easy. Among them, the line type using a full multi type recording means in which a large number of ejection openings are arranged in the paper width direction can further speed up recording.

The above-mentioned ink jet recording apparatus is provided with a head recovery device for preventing clogging in the flow path, and is appropriately provided in the head recovery device with the ejection port forming surface of the recording head capped. The ink is sucked by the suction means and the ink in the flow channel is forcibly discharged from the discharge port to remove the thickened ink in the flow channel. Improves reliability. Further, the recording head used in the above-mentioned ink jet recording apparatus is generally configured such that one recording head can eject one color of ink, but recently, it is a liquid chamber separation type in the same head. There is also a structure in which a plurality of colors can be ejected.

In the recording head of the latter structure, a plurality of colors
Since it is possible to eject with one head, the number of heads can be reduced even when printing a color image using multiple colors of ink or multilevel recording using multiple inks of similar colors but different densities. It is possible to reduce the size and cost of the device.

[0006]

However, when the ink suction operation is performed in order to prevent clogging of the head, defective ejection, and the like, when the ink that can be ejected by one recording head is of one color, the suction is performed. Since only one color of ink remained in the cap for ink, no color mixture occurred in the ejected ink after suction, but in the recording head of the liquid chamber separation type that allows multiple colors to be ejected in the same head, Since a plurality of colors of ink remain in the cap for use, there is a problem that a phenomenon occurs in which mixed colors occur in the ejected ink after suction.

In particular, the color mixture of ink colors in an ink tank having a high negative pressure is more intense than that in an ink tank having a low negative pressure.

Further, in order to eliminate the color mixture of the ejected ink, it is necessary to eject the ink until the color mixture is not seen, so that the ink is wastefully consumed.

In view of the above-mentioned problems of the prior art, the present invention causes wasteful ink consumption for mixed colors after suction when an ink jet head of a liquid chamber separation type capable of ejecting a plurality of colors in the same head is used. It is an object of the present invention to provide an ink jet recording apparatus that can be efficiently eliminated and can always perform stable and high quality recording.

[0010]

In order to achieve the above object, the present invention is an ink jet system which is connected to an ink tank of each color for holding a plurality of colors of ink and is capable of ejecting a plurality of colors in the same head of a liquid chamber separation type. An ink jet recording apparatus including at least a head and a cap means disposed outside the recording area to face the head, capping the entire ejection port forming surface of the head to suck ink, and used for preliminary ejection of ink. In the above, the negative pressure difference from the ink tank of the minimum negative pressure among the ink tanks of the respective colors is obtained for each ink tank of the respective colors, and after the suction by the cap means, the negative pressure difference of the ink tanks of the respective colors is determined. The present invention is characterized in that a control means for varying the number of preliminary ejections is provided for each corresponding ink ejection port array.

Further, an ink jet head which is connected to an ink tank of each color for holding a plurality of colors of ink and is capable of ejecting a plurality of colors in the same head, and is arranged outside the recording area so as to face the head. In an inkjet recording apparatus including at least a cap unit that caps the entire ejection port forming surface of the head to suck ink and is used for preliminary ejection of ink, the ink of the minimum negative pressure in the ink tank of each color The negative pressure difference from the tank is obtained for each ink tank of each color, and the suction force by the cap means is changed according to the value of the maximum negative pressure difference among the obtained negative pressure differences. It is characterized in that a control means is provided for varying the number of preliminary ejections for each ink ejection port array corresponding to each color according to the negative pressure difference. In this case, as the negative pressure difference in the ink tank increases, the suction force for performing the suction operation is performed with a low suction force.

In any one of the above ink jet recording apparatuses, as the negative pressure difference in the ink tank increases,
The number of preliminary ejections after suction is increased, and the negative pressure is a static negative pressure and a dynamic negative pressure generated at the time of recovery operation, and ink is detected by detecting the ink remaining amount in the ink tank. The present invention includes a means for estimating the negative pressure of the tank, wherein the number of preliminary ejections after the suction is smaller in the central portion than in the end portions of the ink ejection port array.

[0013]

When the ink which can be ejected by one recording head is of one color, the ejection port forming surface of the head is capped by the cap unit, and the ink is forcibly sucked from the ink ejection port array by the cap unit. Then, ejection failure and clogging of the head are eliminated.

However, in an ink jet head of the liquid chamber separation type capable of ejecting a plurality of colors in the same head, when ink is sucked from the ink ejection port array by being capped by the cap means, the negative pressure of the ink tank of each color is different. When the negative pressure of the ink tank is high, another color of ink enters the common liquid chamber through the liquid passage from the ink ejection port, resulting in color mixing.

Therefore, in the present invention, the negative pressure of the ink tank of each color is detected by the control means, and after the suction by the cap means, the negative pressure difference from the ink tank of the minimum negative pressure among the ink tanks of the respective colors is detected. By changing the number of preliminary ejections for each ink ejection port array corresponding to each color, it is possible to eliminate the color mixture that occurs after suction without wasteful ink ejection.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of each main constituent part of an ink jet recording apparatus for suitably implementing the present invention will be described with reference to the drawings.

(1) Description of Recording Apparatus FIG. 1 is a perspective view showing a main structure of an ink jet recording apparatus of the present invention. The inkjet recording apparatus of the present invention is
As shown in FIG. 1, an inkjet head unit 11 having an ejection port array for ejecting ink (see FIGS. 2 and 3)
It has. The inkjet head unit 11 is mounted on a carriage 13, the carriage 13 is slidably guided and supported by a guide shaft 12, and is engaged with a part of a drive belt 14. The drive belt 14 is wound around two pulleys, and the rotary shaft of the carriage motor 15 is an encoder (not shown) on either one of the pulleys.
It is connected with. As a result, the carriage 13
Is driven by the carriage motor 15 by the drive belt 14
It is reciprocally moved along the guide shaft 12 via.

On the other hand, the recording material P made of paper, plastic thin plate, or the like passes through a conveying roller (not shown) and then the discharge roller 1
It is sandwiched by 7 and is fed in the direction of the arrow when a conveyance motor (not shown) is driven.

A heating element (electrical / thermal energy converter) for generating thermal energy for ink ejection is provided inside the ink ejection port (liquid path) of the ink jet head unit 11. Then, according to the reading timing of the encoder (not shown), the heating element is driven according to the recording signal, and the ink droplets are ejected and adhered onto the recording material P to form an image. .

A head recovery device having a cap portion 16 is installed at the home position (HP) of the carriage selected outside the recording area. When not recording,
The carriage 13 is moved to the home position (HP) to seal the ink ejection port forming surface of the inkjet head unit 11 with the cap portion 16, and the ink is fixed due to the evaporation of the ink solvent, dust or foreign matter such as paper dust is attached. Prevents clogging due to. Further, the capping function of the cap portion 16 ejects ink to the cap portion 16 which is away from the ink ejection port in order to eliminate ejection failure and clogging due to ink thickening, sticking, etc. of the ink ejection port with low recording frequency. It is used for a preliminary ejection mode to be performed, or a pump (not shown) is operated in a capped state to suck ink from the ink ejection port, and is used for ejection recovery of the ink ejection port having ejection failure. Further, by disposing the blade at a position adjacent to the cap portion, it is possible to clean (wiping) the ink ejection port forming surface of the inkjet head unit 11.

(2) Description of Recording Head FIG. 2 is a schematic perspective view of an ink jet recording head of a liquid chamber separation type capable of ejecting a plurality of colors in the same head as seen from the ink ejection port array side, and FIG. 3 is a partial perspective view schematically showing the structure of an ink ejection portion of the inkjet recording head shown in FIG. 2. FIG. In FIG. 2 and FIG. 3, the recording head 21 has an ejection port surface 22 having a plurality of ejection ports 23 that are open, and is required for ejecting ink to the liquid passage portion 31 communicating with the ejection port 23. The ejection energy generating elements 32 that generate the energy to generate the energy are arranged. Figure 2
The middle arrow y indicates the scanning direction of the carriage 13 shown in FIG. In this embodiment, a thermistor 33, which is a temperature detecting means for detecting the temperature of the recording head, is arranged between the liquid passage portions 31. The temperature detecting means is not particularly limited to this, and another sensor such as a diode sensor may be used, and the head temperature may be calculated from the duty of the print dot.

(3) Description of Control Configuration FIG. 4 is a block diagram showing the control configuration of the ink jet recording apparatus of the present invention. As shown in FIG. 4, the control configuration of the inkjet recording apparatus of the present invention is such that an image input unit 403 for accessing the main bus line 405,
Image signal processing unit 404 and central control unit CP corresponding thereto
A software processing unit such as U400, an operation unit 406,
The recovery system control circuit 407, the inkjet head temperature control circuit 414, and the head drive control circuit 415 are roughly divided into hardware system processing means.

The CPU 400 normally has a ROM 401 and a random memory (RAM) 402, and applies a proper recording condition to input information to drive a recording head 413 to perform recording. Further, a program for executing a timing chart of the head recovery operation is stored in advance in the RAM 402, and recovery conditions such as preliminary ejection conditions are given to the recovery system control circuit 407, the print head, the heat retention heater, etc. as necessary. .

The recovery system motor 408 drives the above-described recording head 413 and the cleaning blade 409, the cap 410, and the suction pump 411 facing and separated from the recording head 413.

The head drive control circuit 415 executes drive conditions for the electrothermal transducers for ink ejection of the recording head 413, and normally causes the recording head 413 to perform preliminary ejection and recording ink ejection.

On the other hand, a heat retaining heater is provided on the substrate of the recording head 413 on which the electrothermal converter for ejecting ink is provided, and the ink temperature in the recording head can be adjusted by heating to a desired set temperature. it can.

The thermistor 412 is also provided on the above-mentioned substrate, and is for measuring the ink temperature substantially inside the recording head. Thermistor 4
Similarly, 12 may not be provided on the substrate but may be provided outside or near the periphery of the recording head.

Next, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 5 shows a schematic construction of an ink jet recording head and an ink tank of a liquid chamber separation type capable of ejecting a plurality of colors in the same head in the first embodiment of the present invention. View from the direction in which the outlets are arranged,
FIG. 6 is a schematic configuration diagram of the ink jet recording head and the ink tank viewed from the Y direction shown in FIG.

As shown in FIGS. 5 and 6, an ink tank 56 having an atmosphere communication port 57 for exchanging the ink and the atmosphere and containing an absorber 58 for holding the ink is connected to the head. There is. The ink is supplied to the inside of the head from the ink tank 56, the liquid passage 52 in which the discharge heater is provided inside the ink ejection port 55, the common liquid chamber 53 communicating with the liquid passage 52, and the ink supply communicating with the common liquid chamber 53. Filter 5 for trapping dust in the ink in the path 51
It is done through 4. Then, by dividing the common liquid chamber into four, four colors of ink of A color, B color, C color, and D color can be ejected in one head. It should be noted that the four colors A to D may be black, cyan, magenta, and yellow, or four color inks of similar colors but having different dye densities of the inks.

When the head is sucked, four colors are sucked at once by one suction cap. Therefore, if the negative pressures of the ink tanks of the four colors are different, the negative pressures of the ink tanks will be different. High-color inks of other colors enter the common liquid chamber 53 from the ink ejection port 55 through the liquid passage 52, and thus color mixing or defective density occurs.

FIG. 7 is a graph showing the results of examining the negative pressure difference from the ink tank having the minimum negative pressure and the number of preliminary ejections required to remove the ink mixed with the color after suction. That is, it was found that the larger the negative pressure difference from the minimum negative pressure ink tank, the larger the number of preliminary ejections required to remove the ink mixed with the color after suction.

FIG. 8 is a flow chart showing the head recovery operation in the first embodiment of the present invention. FIG. 9 is a graph showing the results of investigating the negative pressure of an ink tank including an absorber that holds ink and the amount of ink remaining in the ink tank.

In FIG. 8, when the button for head recovery is pressed, START is set, and first, the negative pressures of the ink tanks of the four colors A to D are detected (step S71). Next, the negative pressure difference from the ink tank having the minimum negative pressure is obtained (step S72).

From the relationship between the negative pressure difference in the ink tank shown in FIG. 7 and the number of preliminary discharges required to remove the ink mixed after suction, the minimum negative pressure is required for each color and the remaining three colors. The number of preliminary ejections is selected (step S73). After that, suction (step S74) and wiping (step S74)
75) is performed to clean the ink or the like on the ink ejection port forming surface, the preliminary ejection of the number selected in step S73 for each of the four colors is performed (step S76), and the print standby state is set to END.

As a means for detecting the negative pressure of the ink tank in step S71 shown in FIG.
A means for estimating the negative pressure of the ink tank by detecting the remaining amount of ink based on the relationship shown in FIG.

As mentioned above, in this first embodiment,
Even when using an ink jet recording head capable of ejecting four colors by dividing the liquid chamber into four, it is possible to reduce ink consumption and efficiently prevent color mixing by controlling the number of preliminary ejections of each color after suction. It is possible to always perform stable and high-quality recording.

Further, in the first embodiment, the case where the liquid chamber is capable of ejecting four colors separated into four has been described, but the present invention is not limited to four colors, and two colors, three colors or five or more colors are possible. It may be an ink jet recording head in which the liquid chamber is separated and can be ejected.

The negative pressure referred to in the present embodiment is a static negative pressure and a dynamic negative pressure generated during the recovery operation.

(Second Embodiment) Also in the second embodiment, the liquid chamber shown in FIGS. 5 and 6 is divided into four parts.
An inkjet recording head capable of color ejection and an ink tank will be described.

FIG. 10 is a flow chart showing the recovery operation in the second embodiment of the present invention.

In FIG. 10, when the button for performing recovery is pressed, it is set as START.
The negative pressure of each color ink tank is detected (step S9).
1). Next, the negative pressure difference from the ink tank having the minimum negative pressure is obtained (step S92).

Then, the suction force corresponding to the value of the maximum negative pressure difference is selected from the obtained negative pressure differences (step S93), and the number of preliminary ejections corresponding to the suction force and the negative pressure difference of the ink tank is set for each of the four colors. Select (step S94).

After the suction amount (step S95) necessary for recovery with the suction force selected in step 93 is performed, the ink or the like on the ink ejection port forming surface is cleaned by wiping (step S96). The preliminary ejection of the number selected in step S94 is performed for each of the four colors (step S97), and the print standby state is set to END. From the relationship between the negative pressure difference from the minimum negative pressure ink tank shown in FIG. 7 and the number of preliminary ejections required to remove the ink that has been mixed after suction, the negative pressure differences a and b of the ink tanks can be compared. It can be seen that the larger the pressure difference is, the larger the number of preliminary ejections required to remove the mixed color ink after suctioning.

FIG. 7 in which the negative pressure difference of the ink tank is a> b
FIG. 11 is a graph showing the results of investigating the suction force for performing the suction operation for a and b and the number of preliminary ejections required to remove the ink mixed with the color after the suction.

By performing a suction force for both a and b with a low suction force, it is possible to reduce the number of preliminary discharges after suction, and a with a large negative pressure difference in the ink tank has a suction force lower than b. It can be seen from FIG. 11 that the subsequent preliminary ejection numbers do not reach an equilibrium state.

From this, in step S93 of FIG. 10, the suction force at which the number of preliminary discharges after suction with the maximum negative pressure difference obtained in step 92 is in a guarded state is selected.

In step S94 of FIG. 10, the negative pressure difference of the ink tank shown in FIG. 7 for the suction force selected in step S93 and the relationship between the number of preliminary ejections required to remove the ink mixed after the suction are compared. , The number of preliminary discharges required for one color of the minimum negative pressure and each of the remaining three colors are selected (step S73).

As described above, in this second embodiment,
Since the ink consumption can be further reduced and the color mixture after suction can be efficiently prevented, stable and high-quality recording can be always performed. Further, the suction force with which the number of preliminary discharges after suction is balanced due to the maximum negative pressure difference that may occur in advance may be set to the suction force for performing the suction operation.

The negative pressure in this embodiment is a static negative pressure and a dynamic negative pressure generated during the recovery operation.

(Third Embodiment) FIG. 12 is a diagram showing a negative pressure difference from an ink tank having a minimum negative pressure and a preliminary discharge at an end portion and a central portion of an ink discharge port array necessary for removing ink mixed in color after suction. It is a graph which shows the result of having investigated the number.

It can be seen from FIG. 6 that the larger the negative pressure difference of the ink tank, the larger the number of preliminary ejections required to remove the mixed color ink after suctioning. It can be seen from FIG. 12 that the number of preliminary discharges in a part is small.

Therefore, in the third embodiment, when the preliminary ejection number is selected in the recovery operation shown in FIG. 8 or 10, the central portion of the ink ejection row is set to be small, Since the consumption amount can be further reduced and the color mixture after suction can be prevented much more efficiently, stable and high-quality recording can always be performed.

The negative pressure in this embodiment is a static negative pressure and a dynamic negative pressure generated during the recovery operation.

[0055]

As described above, the present invention is a cap means for an ink jet head which is connected to an ink tank of each color for holding a plurality of colors of ink and is capable of ejecting a plurality of colors in the same head of a liquid chamber separation type. When performing the recovery processing operation using the ink tank of each color, the negative pressure difference from the ink tank of the minimum negative pressure among the ink tanks of each color is obtained for each ink tank of each color, and the ink tank of each color is sucked by the cap unit. The ink jet recording apparatus is provided with a control unit that changes the number of preliminary ejections for each ink ejection port row corresponding to each color according to the negative pressure difference of each color. It can be solved efficiently without doing. As a result, stable and high-quality recording can always be performed.

Furthermore, if the ink is sucked by the cap means with the suction force that balances the number of preliminary ejections after the suction with the maximum negative pressure difference, the ink consumption can be further reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main configuration of an inkjet recording apparatus of the present invention.

FIG. 2 is a schematic perspective view of an ink jet recording head of a liquid chamber separation type capable of ejecting a plurality of colors in the same head as seen from the ink ejection port array side.

FIG. 3 is a partial perspective view schematically showing the structure of an ink ejection portion of the inkjet recording head shown in FIG.

FIG. 4 is a block diagram showing a control configuration of the inkjet recording apparatus of the present invention.

FIG. 5 shows a schematic configuration of an ink jet recording head of a liquid chamber separation type capable of ejecting a plurality of colors in the same head and an ink tank according to the first embodiment of the present invention, as viewed from a direction in which ejection ports are arranged. It is a figure.

6 is a schematic configuration diagram of an ink jet recording head and an ink tank as seen from the Y direction shown in FIG.

FIG. 7 is a graph showing the results of an examination of the negative pressure difference from the ink tank having the minimum negative pressure and the number of preliminary ejections required to remove the ink mixed with the color after suction.

FIG. 8 is a flowchart showing a head recovery operation in the first embodiment of the present invention.

FIG. 9 is a graph showing the results of investigating the negative pressure of an ink tank including an absorber that holds ink and the amount of ink remaining in the ink tank.

FIG. 10 is a flowchart showing a recovery operation in the second embodiment of the present invention.

FIG. 11 is a graph showing the results of an investigation of the suction force for performing the suction operation for a and b in FIG. 7 in which the negative pressure difference of the ink tank is a> b and the number of preliminary ejections required to remove the ink mixed with the color after suction. Graph showing

FIG. 12 is a graph showing the results of an investigation of the negative pressure difference from the minimum negative pressure ink tank and the preliminary ejection numbers at the ends and the center of the ink ejection port array required to remove the ink that has been mixed in color after suction. .

[Explanation of symbols]

 11 Inkjet Head Unit 12 Guide Shaft 13 Carriage 14 Drive Belt 15 Carriage Motor 16 Cap Part 17 Paper Ejection Roller 21 Recording Head 22 Ejection Port Forming Surface 23 Ejection Port 31 Liquid Passage 32 Emission Energy Generating Element 33 Thermistor 51 Ink Supply Path 52 Liquid Channel 53 Common liquid chamber 54 Filter 55 Ink ejection port 56 Ink tank 57 Atmosphere communication port 58 Absorber 400 CPU 401 ROM 402 RAM 403 Image input unit 404 Image signal processing unit 405 Bus line 406 Operation unit 407 Recovery system control circuit 408 Recovery system Motor 409 Blade 410 Cap 411 Pump 412 Thermistor 413 Head 414 Head temperature control circuit 415 Head drive control circuit

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B41J 2/185 B41J 3/04 102 R

Claims (7)

[Claims] 1. An ink jet head, which is connected to an ink tank of each color for holding a plurality of colors of ink and is capable of ejecting a plurality of colors in the same head, is disposed in the same head so as to face the head outside the recording area. An ink jet recording apparatus comprising at least a cap means for capping the entire ejection port forming surface of the head to suck ink, and used for preliminary ejection of ink, wherein the ink of the minimum negative pressure in the ink tank of each color is used. A control for obtaining a negative pressure difference from each tank for each color ink tank, and varying the number of preliminary ejections for each ink ejection port row corresponding to each color according to the negative pressure difference of each color ink tank after suction by the cap means An inkjet recording apparatus comprising means. 2. An ink jet head, which is connected to an ink tank of each color for holding a plurality of colors of ink and is capable of ejecting a plurality of colors in the same head, and is arranged opposite to the head outside the recording area. An ink jet recording apparatus comprising at least a cap means for capping the entire ejection port forming surface of the head to suck ink, and used for preliminary ejection of ink, wherein the ink of the minimum negative pressure in the ink tank of each color is used. The negative pressure difference from the tank is obtained for each ink tank of each color, and the suction force by the cap means is changed according to the value of the maximum negative pressure difference among the obtained negative pressure differences. An ink jet recording apparatus including a control unit that varies the number of preliminary ejections for each ink ejection port array corresponding to each color according to the negative pressure difference. . 3. The ink jet recording apparatus according to claim 2, wherein the suction force for performing the suction operation is performed with a low suction force as the negative pressure difference in the ink tank increases. 4. The ink jet recording apparatus according to claim 1, wherein the number of preliminary ejections after suction is increased as the negative pressure difference in the ink tank increases. 5. The ink jet recording apparatus according to claim 1, wherein the negative pressure is a static negative pressure and a dynamic negative pressure generated during a recovery operation. 6. The ink jet recording apparatus according to claim 1, further comprising means for estimating a negative pressure of the ink tank by detecting a remaining amount of ink in the ink tank. 7. The ink jet recording apparatus according to claim 1, wherein the number of preliminary ejections after the suction is smaller in the central portion than in the end portions of the ink ejection port array.