Recording apparatus and recording method

Abstract

To suppress occurrence of poor discharge defect due to breakage of meniscus of a nozzle of a recording head, in recording an image having less ink discharged.SOLUTION: A carriage is moved so that an absolute value of acceleration at least either at the time of accelerating the carriage or at the time of decelerating the carriage, in a first area is smaller than an absolute value of acceleration at the time of accelerating the carriage or at the time of decelerating the carriage, in a second area.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a recording apparatus and a recording method.

Background Art

[0002] Patent Document 1 discloses a configuration in which, in an inkjet recording apparatus, ink is supplied from an ink tank that stores ink using a head pressure difference to a recording head via a tube.

[0003] In such an inkjet recording apparatus, by maintaining a negative pressure state in the recording head using a head pressure difference, a meniscus is held by the surface tension generated at the nozzles of the recording head to prevent the ink from dripping. Then, as the pressure in the recording head decreases with the ejection of ink from the recording head, the recording head is filled with ink from the ink tank via the supply tube.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the recording head reciprocates, inertial force acts on the ink in the tube due to acceleration and deceleration. When recording an image with less ink ejection from the recording head, since the pressure drop in the recording head due to ink ejection does not occur much, the pressure in the recording head gradually increases due to the inertial force caused by the movement of the recording head. When the pressure in the recording head increases, the meniscus of the ink stretched at the nozzles breaks, and there is a risk of ejection failure due to the ink spreading on the nozzle surface.

[0006] The present invention has been made in view of the above problems, and an object thereof is to suppress the occurrence of ejection failure due to breakage of the meniscus of the nozzles of the recording head even when recording an image with less ink ejection.

Means for Solving the Problems

[0007] The present invention includes an ink tank for storing ink, Based on the image data a recording head having nozzles for ejecting ink, a carriage on which the recording head is mounted and reciprocates in a predetermined direction, carriage control means for moving the carriage, and a connection between the recording head and the ink tank. A supply tube that supplies ink from the ink tank into the recording head and whose bent portion moves as the carriage moves in the predetermined direction, acquisition means for acquiring information regarding the amount of ink ejected onto one band, which is an area recordable when the carriage moves in one direction of the predetermined direction, based on the image data; A recording apparatus having: a region in which the pressure changes in a direction in which the negative pressure in the recording head weakens in an acceleration / deceleration region where the speed changes due to acceleration or deceleration of the carriage in the movement region of the carriage is defined as a first region; When a region in which the pressure changes in a direction in which the negative pressure in the recording head increases in the acceleration / deceleration region of the carriage is defined as a second region, the carriage control means causes the acceleration of the carriage to accelerate or decelerate in the first region. The carriage is moved so that the absolute value of the acceleration is smaller than the absolute value of the acceleration of the carriage that accelerates or decelerates in the second region the carriage control means moves the carriage such that the absolute value of the acceleration of the carriage in the first region is smaller than the absolute value of the acceleration of the carriage in the second region, or makes the absolute value of the acceleration of the carriage in the first region the same as the absolute value of the acceleration of the carriage in the second region, according to the amount of ink ejected onto the one band indicated by the information acquired by the acquisition means, and determines whether to move the carriage based on the determination characterized by that.

Effects of the Invention

[0008] According to the present invention, it is possible to suppress the occurrence of ejection failure due to breakage of the meniscus.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] <Mechanical Configuration of Inkjet Recording Apparatus> <Overall Schematic of the Apparatus> FIG. 1 is a perspective view showing the internal structure of an inkjet recording apparatus (hereinafter also referred to as a recording apparatus) according to the present embodiment. It is a so-called serial scan type recording apparatus that forms an image by scanning a recording head 3 in a main scanning direction (Y direction) intersecting the conveyance direction (X direction) of a recording medium P. In the figure, the X direction is the conveyance direction of the recording medium, the Y direction is the scanning direction of the carriage, and the Z direction is the vertical direction.

[0011] The configuration of this recording apparatus and an outline of the operation during recording will be described with reference to FIG. 1. First, a conveyance motor (not shown) is driven, and the recording medium P is conveyed to a position facing the recording head 3 by a conveyance roller 26 driven from the conveyance motor via a gear. When the recording medium P is conveyed to a position facing the recording head 3, the carriage 2 is moved (scanned) along a guide shaft 5 extending in the main scanning direction by a carriage motor (not shown). A carriage belt 6 is used to transmit the driving force from the carriage motor to the carriage 2. Alternatively, instead of the carriage belt, for example, a lead screw that is rotationally driven by a carriage motor and extends in the main scanning direction, and an engaging portion provided on the carriage 2 and engaged with the groove of the lead screw can be used, and other driving methods can also be used.

[0012] While moving the carriage 2, ink is ejected from the ink ejection ports (nozzles) of the recording head 3 that is detachably attached to the carriage 2 at a timing based on a position signal obtained by an encoder (not shown), and an image with a constant bandwidth corresponding to the nozzle array range is recorded. The ink ejected from the recording head 3 is the ink supplied from the ink stored in the ink supply system 8 to the recording head 3 through the supply tube. One band is the area that the recording head 3 can move in one direction and record. In this embodiment, it is configured to scan at a scan speed of 40 inches per second and perform the ejection operation at a timing of 600 dpi (dots per inch). After that, the recording medium is conveyed, and recording is further performed for the next bandwidth. In such a recording apparatus, recording may be performed by conveying the recording medium by the bandwidth between each scan, or the conveyance may not be performed by the bandwidth per scan, and conveyance may be performed after multiple scans. Also, data thinned out by a predetermined mask is recorded per scan, then paper feed is performed around 1 / n band before and after, and scanning is performed again, so that multi-pass recording may be performed in which multiple scans and conveyance with different nozzles for recording are performed for one band.

[0013] A flexible wiring board for supplying signal pulses for ejection drive, signals for head temperature control, etc. is attached to the recording head 3. The other end of the flexible board is connected to a control circuit (described later) provided with a control circuit that executes the control of this recording apparatus.

[0014] <Recording head configuration> FIG. 2 is a schematic perspective view showing the recording head 3 mounted on the carriage 2 of the above recording apparatus from the direction in which ink is ejected.

[0015] The recording head 3 is capable of ejecting inks of different color tones (including color and density) in the main scanning direction S. In this embodiment, inks of black (Bk), gray (Gy), light gray (Lgy), light cyan (Lc), cyan (C), light magenta (Lm), magenta (M), and yellow (Y) can be ejected. A plurality of recording elements arranged in the X direction corresponding to each of the plurality of inks, and rows 101 to 108 of nozzles provided corresponding to each recording element are juxtaposed in the Y direction on two ejection element substrates 100. For each recording element row, a supply tube 4 for each ink is connected to the connection portion 25, and the ink is supplied from the ink supply system 8 through the connection portion 25 and via the ink flow path inside the recording head 3. The supplied ink forms a meniscus on the surface of the nozzle due to surface tension. The ink does not come out of the recording head 3 unless a pressure change exceeding the pressure resistance of the meniscus occurs. Here, a recording head capable of ejecting 8-color inks is taken as an example, but there is no limitation on the ink color and the number of colors in the recording head. Specifically, a recording head that ejects only black (Bk) ink or a recording head that ejects 4-color inks such as black (Bk), cyan (C), magenta (M), and yellow (Y) may be used.

[0016] (Block diagram) FIG. 3 is a diagram showing a block configuration of the control system of the inkjet recording apparatus 1. The ROM 402 is a non-volatile memory, and stores, for example, a control program for controlling the inkjet recording apparatus 1 and a program for realizing the operation of this embodiment. The operation of this embodiment is realized, for example, by the CPU 401 reading out the program stored in the ROM 402 to the RAM 403 and executing it. The RAM 403 is also used as a working memory of the CPU 401. The EEPROM 404 stores data that should be retained even when the power of the inkjet recording apparatus 1 is turned off.

[0017] The interface (I / F) circuit 410 connects the inkjet recording apparatus 1 to an external network such as a LAN. The inkjet recording apparatus 1 performs transmission and reception of various jobs, data, etc. with devices such as an external host computer via the I / F circuit 410.

[0018] The input / output unit 406 includes an input unit and an output unit. The input unit receives an instruction to turn on the power, an instruction to execute recording, and an instruction to set various functions from the user. The output unit displays various device information such as the power saving mode and a setting screen for various functions that the inkjet recording apparatus 1 can execute. In the present embodiment, the input / output unit 406 is an operation panel provided in the inkjet recording apparatus 1, and the input / output unit 406 is connected via the input / output control circuit 405 so as to be able to transmit and receive data with the system bus 416. In the present embodiment, the CPU 401 performs notification control of the information of the output unit.

[0019] In addition, the input unit may be a keyboard of an external host computer, and it may be possible to receive a user's instruction from the external host computer. The output unit may be an LED display, an LCD display, or a display connected to the host device. Also, when the input / output unit is a touch panel, it is possible to receive a user's instruction by software keys. Further, the input / output unit 406 may be a speaker and a microphone, and the input from the user may be voice input and the notification to the user may be voice output.

[0020] An information processing apparatus having a CPU and a ROM having the same functions as the CPU 401 and the ROM 402 and externally connected to the inkjet recording apparatus 1 may perform the recording medium determination process described later and determine the recording medium to be used in the inkjet recording apparatus 1.

[0021] The recording head control circuit 411 supplies a drive signal corresponding to the recording data to the nozzle drive circuit mounted on the recording head 3 and including a selector and a switch, and controls the recording operation of the recording head 3 such as the drive order of the nozzles. For example, when print data is transmitted from the outside to the I / F circuit 410, the print data is temporarily stored in the RAM 403. Then, the recording head control circuit 411 drives the recording head 3 based on the recording data converted from the print data into the recording data for recording. At this time, the conveyance motor drive circuit 412 drives the conveyance motor 413 based on the bandwidth of the recording data or the like, and the conveyance roller 26 connected to the conveyance motor 413 rotates to convey the recording medium. The CR (carriage) motor drive circuit 414 drives the CR (carriage) motor 415 to scan the carriage 2 along the guide rail 5 via the carriage belt 6.

[0022] The data sent from the I / F circuit 410 includes not only print data but also data of the contents set by the printer driver. Also, the print data may be received from the outside via the I / F circuit 410 and stored in the storage unit, or may be stored in advance in a storage unit such as a hard disk. The CPU 401 reads the print data from the storage unit and controls the image processing circuit 409 to execute conversion (binarization processing) into recording data for using the recording head 3. The image processing circuit 409 executes various image processes such as color space conversion, HV conversion, gamma correction, and rotation of the image in addition to the binarization processing.

[0023] Also, the CPU 401 calculates the average duty of the ink for each band based on the recording data. In this embodiment, when driving 2 dots of ink at a 1 / 600 inch (600 dpi) square is counted as duty 100%. The calculated average duty is temporarily stored in the RAM 403, acquired from the RAM 403 when determining the speed of the carriage 2, and used for determining the speed of the carriage 2.

[0024] <Configuration of Ink Supply System> (Ink Supply System) FIG. 4 is a schematic diagram showing the configuration of the ink supply system of this embodiment, that is, the ink supply system 8, the recording head 3, and the supply tube 4 connecting the ink supply system and the recording head. Actually, an ink supply system and a supply tube are provided for each color, but here, the description will be made using a diagram of the ink supply system and the supply tube for one color.

[0025] In FIG. 3, the ink supply system 8 includes a main tank 9, a sub-tank 10, a hollow tube 11 connecting the sub-tank 10 and the main tank 9, a buffer chamber 12, and a communication tube 21 connecting the main tank 9 and the buffer chamber 12. The supply tube 4 is made of a flexible material and connects the sub-tank 10 and the recording head 3. The supply tube 4 connected to the sub-tank 10 has a portion parallel to the moving scanning direction of the carriage 2 and extends with a bent portion in the middle so as to be connected to the left side of the recording head 3 in the figure, and is folded back and runs around inside the recording apparatus main body. The supply tube 4 is arranged so as to have a portion parallel to the guide rail 5. Note that the arrangement of the supply tube 4 shown in FIG. 2 is merely an example and is not limited to this.

[0026] The main tank 9 shown in FIG. 3 is detachably mounted on the recording apparatus main body. In the inkjet recording apparatus of this embodiment, the main tank 9 stores a larger amount of ink than the sub-tank 10. Further, the main tank 9 is communicated with the sub-tank 10 by the hollow tube 11 and is communicated with the buffer chamber 12 by the communication tube 21. The main tank 9 is configured to be connected at the bottom of the mounting state of the hollow tube 11 and the communication tube 21 to the main tank 9, and is sealed except for the connection portion.

[0027] Note that the main tank 9 in this study may be in the form of a detachable cartridge or in the form of injecting ink from a bottle into the main tank 9.

[0028] (Pressure fluctuation) As described above, the supply tube 4 connected to the sub-tank 10 extends having a portion parallel to the Y direction which is the moving direction of the carriage 2, and has a bent portion that is folded midway so as to be connected from the -X side (left side in FIG. 4) of the recording head 3 and crawls inside the recording apparatus main body. The length L from the bent portion of the supply tube 4 to the connection portion 25 with the recording head 3 changes as the carriage 2 reciprocates. In this embodiment, by configuring the bent portion on the left side of the apparatus, when the carriage 2 scans in the forward path moving from the right side to the left side in FIG. 1, the length L from the bent portion to the recording head 3 connection portion shortens as the supply tube 4 moves. Also, when the carriage 2 scans in the return path moving from the left side to the right side, the length L from the bent portion to the recording head 3 connection portion lengthens as the supply tube 4 moves. Thus, when the supply tube moves following the reciprocating movement of the carriage 2, an inertial force acts on the ink 7 inside the length L from the bent portion to the recording head 3 connection portion. This inertial force is generated when the carriage 2 accelerates and decelerates, and a dynamic pressure is generated that varies the internal pressure in the recording head 3 by the movement of the ink 7 in the supply tube 4 with respect to the recording head 3.

[0029] (Pressure fluctuation parameter) The amount of pressure fluctuation in the recording head 3 is determined by the length L from the supply tube 4 to the connection part of the recording head 3 and the magnitude of acceleration or deceleration. Fig. 4 is a schematic diagram showing how much pressure fluctuation is generated due to the movement of ink when a pressure measuring device is installed in the supply tube 4 and acceleration is applied to the carriage 2. A pressure measuring device 19 is provided for the supply tube 4, and the pressure fluctuation immediately before the connection part to the recording head 3 when the carriage 2 accelerates from left to right in the figure in Fig. 4 is measured. At that time, the acceleration of the carriage 2 and the length L from the bent part in the supply tube 4 to the connection part of the recording head 3 when the carriage 2 starts to accelerate are changed. The measurement results are shown in Fig. 5. It can be seen that there is a proportional relationship when the product of the acceleration of the carriage 2 and the length L from the bent part in the supply tube 4 to the connection part of the recording head 3 at the start of acceleration is taken on the horizontal axis and the amount of pressure fluctuation converted from the output value of the pressure measuring device 19 is taken on the vertical axis. From this, it can be seen that the greater the acceleration of the carriage 2 and the greater the length L from the bent part in the supply tube 4 to the connection part of the recording head 3, the greater the pressure fluctuation in the recording head.

[0030] On the other hand, the relationship with deceleration was also measured in the same way. The measurement results are shown in Fig. 7 with the product of the deceleration of the carriage 2 and the length L from the bent part in the supply tube 4 to the connection part of the recording head 3 at the start of deceleration on the horizontal axis and the amount of pressure fluctuation converted from the output value of the pressure measuring device 19 on the vertical axis, similar to when measuring acceleration. It can be seen that there is a similar proportional relationship in deceleration as in acceleration. Although the slope changes depending on the diameter of the supply tube and the viscosity of the ink in the above-described results, the proportional relationship remains unchanged.

[0031] Next, the pressure fluctuations when accelerating and decelerating were repeatedly measured, albeit intermittently. The results are shown in Fig. 8, with time on the horizontal axis, the speed of carriage 2 indicated by a dotted line on the vertical axis, and the measured pressure values indicated by a solid line. First, carriage 2 is moved to the left from the state shown in Fig. 4. Then, since a rightward inertial force acts on the ink 7 in supply tube 4, the ink 7 moves to the right, and as a result, the measured pressure value shifts to the positive pressure side. When carriage 2 reaches the target speed and maintains a constant speed, and moves at a constant speed to a predetermined position, it decelerates to a speed of 0 when it reaches the left end. When deceleration starts, an inertial force acts on the ink 7 in supply tube 4 in the leftward direction, so the ink moves to the left. As a result, the measured pressure value shifts to the negative pressure side. When carriage 2 moves from the left end to the right end, the opposite of the above-described phenomenon occurs. Therefore, during acceleration, the pressure shifts to the negative pressure side, and during deceleration at the right end, the pressure shifts to the positive pressure side. That is, in the reciprocating motion of carriage 2 in Fig. 5, the acceleration and deceleration when carriage 2 is on the right side vary to the positive pressure side, and the acceleration and deceleration when carriage 2 is on the left side vary to the negative pressure side. In this measurement, since carriage 2 was reciprocated intermittently, the pressure fluctuations shifted up and down with 0 as the reference. The pressure fluctuations when carriage 2 is continuously reciprocated will be described below.

[0032] (Transition of Fluctuation Reference) To explain the pressure fluctuations due to continuous reciprocating motion and the pressure reduction due to ink ejection, a pressure measuring device 19 was installed immediately in front of the recording head 3 in the recording device shown in Fig. 1 in the same manner as in Fig. 6, and the pressure fluctuations during printing were measured.

[0033] Figure 9 shows the image pattern used in this verification. Figure 8(a) shows an image pattern simulating a large discharge amount, with the implantation amount per unit area set at 20 ng / 600 dpi. On the other hand, Figure 8(b) shows an image pattern simulating a small discharge amount, with the implantation amount set at 1 ng / 600 dpi. The absolute value of the acceleration was set at 12 m / s / s for both the left and right sides. The measurement results of the pressure fluctuation when printing using the above image data are shown in Figure 9. In the case of Figure 9(a) where the implantation amount is as large as 20 ng / 600 dpi, the reference value (a - 0) of the pressure fluctuation is maintained at approximately 0 mmAq and fluctuates up and down due to the decrease in the internal pressure of the head caused by the ink discharge from the nozzle. On the other hand, in the case of Figure 9(b) where the implantation amount is as small as 1 ng / 600 dpi, since there is almost no ink discharge, there is no decrease in the pressure inside the head. As a result, due to the continuous reciprocating motion of the carriage 2, the reference value (b - 0) of the pressure fluctuation gradually shifts to the pressurizing side. The reason for this shift to the pressurizing side will be explained using Figure 11. Figure 10 is a schematic diagram showing how the length L from the bent portion of the supply tube 4 to the connection portion of the recording head 3 changes as the carriage 2 reciprocates in the image forming apparatus used in this verification. When the carriage 2 is located on the right side, it can be seen that the length L from the bent portion of the supply tube 4 to the connection portion of the recording head 3 is long as shown in Figure 10(a). As the carriage 2 moves to the left side, it becomes shorter as shown in Figure 10(b). As described above, since the inertial force acting on the ink in the supply tube 4 is proportional to the product of the acceleration and deceleration of the carriage 2 and the length L from the bent portion of the supply tube 4 to the connection portion of the recording head 3, the variation range of the pressure increase on the right side is larger than the variation range of the negative pressure on the left side. This is the reason why in the case where the implantation amount is as small as 1 ng / 600 dpi (b), the reference value (b - 0) of the pressure fluctuation shifts to the positive pressure side.

[0034] <Acceleration and deceleration control> In the recording apparatus according to this embodiment, as shown in Figures 8 and 10, the acceleration and deceleration regions exist at both the left and right ends of the reciprocating scan of the carriage 2. In order to obtain the effects of the invention, it is necessary to separately control the acceleration and deceleration at the end that shifts to the positive pressure side and the end that shifts to the negative pressure side.

[0035] The first region and the second region will be described below.

[0036] (First region) The first region in this specification will be described with reference to FIG. 10. When the pressure in the recording head 3 changes to a positive pressure, that is, increases, an inertial force acts on the ink 7 in the supply tube 4 in the direction of the recording head 3 in the acceleration / deceleration region. Looking at FIG. 10(a), since the supply tube is arranged to the left of the recording head 3, in the deceleration region where the carriage 2 decelerates from a constant speed and stops in the state shown in FIG. 10(a), an inertial force acts on the ink 7 in the supply tube 4 in the direction of the recording head 3. Next, an inertial force also acts on the ink 7 in the supply tube 4 in the direction of the recording head 3 in the region where the carriage 2 accelerates from the stopped state to a constant speed. Based on the above, in FIG. 10, in (a), that is, in the acceleration / deceleration region of the carriage 2 on the right side of the recording device, the pressure changes in the direction of weakening the negative pressure in the recording head 3. In this specification, the acceleration / deceleration region on the right side shown in FIG. 10(a) (the side where the negative pressure in the recording head 3 weakens) is defined as the first region.

[0037] (Second region) Similarly, the second region in this specification will be described with reference to FIG. 10. When the pressure in the recording head 3 changes to a negative pressure, that is, decreases, an inertial force acts on the ink 7 in the supply tube 4 in the direction opposite to the recording head 3 in the acceleration / deceleration region. In the deceleration region where the carriage 2 decelerates from a constant speed and stops in the state shown in FIG. 10(b), an inertial force acts on the ink 7 in the supply tube 4 in the direction opposite to the recording head 3. Next, an inertial force also acts on the ink 7 in the supply tube 4 in the direction opposite to the recording head 3 in the region where the carriage 2 accelerates from the stopped state to a constant speed. Based on the above, in FIG. 10, in (b), that is, in the acceleration / deceleration region of the carriage 2 on the left side of the recording device, the pressure changes in the direction of strengthening the negative pressure in the recording head 3. Therefore, in this specification, the acceleration / deceleration region on the left side shown in FIG. 10(b) (the side where the negative pressure in the recording head 3 is strengthened) is defined as the second region.

[0038] The above relationship varies depending on the crawling of the supply tube 4. For example, when the supply tube 4 is connected to the recording head 3 in the right direction and the bent portion is on the right side of the recording head 3, the relationship between the increase and decrease of pressure is reversed. In that case, the first region and the second region are reversed left and right. The above regions are not the positional relationship in the recording apparatus, but are determined only by the increase and decrease of the internal pressure of the recording head 3.

[0039] Hereinafter, the present embodiment will be described in more detail using examples and comparative examples. The present invention is not limited by the following examples as long as the gist thereof is not exceeded. For example, the effects of the present invention are applicable even when the apparatus size, ink color, number of inks, tube length, tube diameter, carriage speed, nozzle diameter of the recording head, etc. are changed.

[0040] <Example 1> In this example, the inkjet recording apparatus shown in FIG. 1 was used. The recording apparatus is an A1 size inkjet printer, and in this example, image data using only black (Bk) was used. The recording head used was not provided with a damper for absorbing dynamic pressure. Also, the printing environment temperature in this example was 25°C.

[0041] (Average duty per band) The printing patterns in the examples and comparative examples in the present invention were set by the average duty per band. When measuring the discharge amount per dot of the recording head 3 used in this example, it was about 11.4 ng. In addition, as the definition of the average duty, when 2 dots of ink are driven into a 1 / 600 inch (600 dpi) square, it was defined as duty 100%. Therefore, when the average duty per band was 100%, the driving amount was 22.8 ng / 600 dpi. In this example, the average duty of black (Bk) per band was set to 5% (which can be converted to a driving amount of 1.1 ng / 600 dpi), and the other colors were set to duty 0%.

[0042] (The first region and the second region) In the following Examples and Comparative Examples, the first region was the acceleration / deceleration region on the right side of the recording apparatus in Fig. 10(a), that is, and the second region was the acceleration / deceleration region on the left side of the recording apparatus in Fig. 10(b). Acceleration and deceleration in each acceleration / deceleration region were all controllable independently. The acceleration and deceleration were determined by the CPU 401, and the carriage motor drive circuit 414 moved the carriage 2 based on the signal for controlling the acceleration sent from the CPU 401. In this Example, as shown in Table 4, the acceleration in the first region was set to 1.0 m / s / s, the deceleration in the first region was set to 20.0 m / s / s, and both the acceleration and deceleration in the second region were set to 20.0 m / s / s. The carriage speed at arrival was set to 40 inch / s.

[0043] (Image evaluation) When the meniscus breaks, ink wets and spreads on the nozzle surface of the recording head, and the ink that tries to be ejected is pulled by the ink that has spread on the nozzle surface and wet non-ejection where the ink is not ejected occurs.

[0044] As an effect confirmation in this Example and Comparative Examples, when each image data was continuously printed on 5 sheets of A1 size plain paper, it was visually determined whether print streaks occurred in the image due to non-ejection. As the image data, a solid image as shown in Fig. 9 was input so that the duty was uniform in each band. When print streaks occurred even partially, it was determined as "with non-ejection", and when there were no print streaks at all and the image was good, it was determined as "without non-ejection". Also, the time required to print 1 sheet of A1 size was measured and evaluated as throughput. The results are shown in Table 4.

[0045] In Example 1, the absolute value of the acceleration during acceleration in the first region was made significantly smaller than the absolute value of the acceleration during acceleration and the absolute value of the acceleration during deceleration in the second region. As a result, an increase in the reference line of the pressure fluctuation could be suppressed to about 25 mmAq, and as a result, print streaks due to non-ejection were not confirmed. Therefore, the printing result was "without non-ejection". Therefore, it was confirmed that deterioration of the image was suppressed compared to Comparative Example 1 where all the acceleration and deceleration were 20.0 m / s / s and non-ejection occurred with an increase in the reference line of the pressure fluctuation of about 75 mmAq.

[0046] <Example 2> Next, as Example 2, the absolute value of the acceleration during deceleration in the first region was set to 1.0 m / s / s, and the absolute value of the acceleration during acceleration was set to 20.0 m / s / s. Also in this case, there were no printing streaks, and the same effects as in Example 1 were obtained.

[0047] <Example 3> In Example 3, the absolute value of the acceleration during acceleration in the first region was set to 1.0 m / s / s, and the absolute values of the acceleration during acceleration and deceleration in the second region were made smaller than 20.0 m / s / s. On the other hand, the absolute value of the acceleration during deceleration in the first region was set to 22.0 m / s / s, which is larger than 20.0. The printing result was "no streaks". The reference line of the pressure fluctuation was slightly larger at 40 mmAq compared to Example 1 and Example 2, but it can be said that there were no printing streaks and deterioration of the image quality was suppressed compared to Comparative Example 1.

[0048] <Example 4> In Example 4, the absolute value of the acceleration during acceleration in the first region was set to 20.0 m / s / s, and the absolute value of the acceleration during deceleration in the first region was set to 1.0 m / s / s. On the other hand, the absolute value of the acceleration during acceleration in the second region was set to 18 m / s / s, and the absolute value of the acceleration during deceleration was set to 20.0 m / s / s. That is, the acceleration in the first region was made larger than the acceleration in the second region, and the absolute values of the acceleration during acceleration and deceleration in the second region were made larger than the absolute value of the acceleration during deceleration in the first region. The printing result was "no streaks", and the reference line of the pressure fluctuation was slightly larger at 30 mmAq compared to Example 1 and Example 2. This is presumably because the deceleration in the second region was reduced, resulting in a smaller inertial quantity for reducing the internal pressure of the head.

[0049] From the results of Example 3 and Example 4, it can be said that there is an effect if at least one of the absolute value of the acceleration during acceleration or the absolute value of the acceleration during deceleration in the first region is smaller than at least one of the absolute value of the acceleration during acceleration or the absolute value of the acceleration during deceleration in the second region.

[0050] <Example 5> In Example 5, the absolute values of the acceleration during acceleration and deceleration in the first region were set to 3.0 m / s / s, both of which were made smaller than the absolute values of the acceleration during acceleration and deceleration in the second region, which were 20.0 m / s / s. Furthermore, the printing duty was set to a lower duty of 3% compared to Examples 1 to 4. When printing under the above conditions, the reference line of the pressure fluctuation during printing fluctuated slightly up and down around 0 mmAq without almost any change. As a result, a good image could be obtained without occurrence of non-ejection. From the viewpoint of pressure fluctuation, a greater effect was observed compared to Examples 1 to 4, and it became possible to handle even a low duty.

[0051] <Example 6> In Example 6, the difference between the absolute value of the acceleration / deceleration in the first region and the absolute value of the acceleration / deceleration in the second region was made smaller compared to the conditions of Example 5. Specifically, the absolute value of the acceleration / deceleration in the first region was set to 5.0 m / s / s, and the absolute value of the acceleration / deceleration in the second region was set to 13.0 m / s / s. As a result, the reference line of the pressure fluctuation shifted in the increasing direction by about 15 mmAq compared to Example 5, but non-ejection did not occur, and a good image could be obtained.

[0052] <Example 7> In Example 7, a recording head provided with the damper device shown in FIG. 12 was used. The ink supplied to the recording head 3 is supplied from the ink communication port 17 through the ink flow path 18 to the ink chamber 19. The ink in the ink chamber 19 is discharged out of the recording head 3 from the discharge port 16 when the recording element 20 is driven. Here, a damper chamber 15 is provided. The damper chamber 15 is made of a flexible member, and the size of the damper chamber changes according to the pressure. The absolute value of the acceleration / deceleration in the first region was set to 18 m / s / s, and the absolute value of the acceleration / deceleration in the second region was set to 20 m / s / s. Compared with Examples 1 to 5, since the absolute value of the acceleration / deceleration in the first region is large, the inertial force on the ink is large, and the reference line of the pressure fluctuation reaches 70 mmAq, which is higher than that of the previous examples. However, no printing streaks were observed in the printing result, and no non-ejection occurred. From the results of this example, it was found that the presence of the damper enables it to withstand larger pressure fluctuations compared to Examples 1 to 6.

[0053] <Example 8> In this embodiment, the minimum necessary acceleration / deceleration reduction is suppressed for the average duty in the image data. In addition, for an image in which there are only low-duty portions in part, it is only necessary to reduce the absolute value of the acceleration / deceleration speed in the first region only for the band corresponding to the relevant portion, and from the viewpoint of throughput, the acceleration / deceleration speed is not restricted for all A1 sizes. Therefore, in Example 8, a recording head without the damper used in Examples 1 to 6 was used, and a table capable of setting the acceleration / deceleration speed of the relevant band corresponding to the average duty per band was prepared in the ROM of the recording apparatus. For the sake of explanation in Table 1, the bands are numbered. The first band at the start of printing is designated as Band No1, and an image of 78 bands in total is input. The image pattern will be described as one in which the average duty decreases every 13 bands. For bands with an average duty of 88% and 50% per band, the discharge amount is large and sufficient decompression in the recording head can be expected, so the absolute value of the acceleration / deceleration speed is not reduced. That is, when the average duty is more than half (50% or more) of the maximum value (100%), the absolute value of the acceleration / deceleration speed is not reduced. In addition, for bands 66 to 78 where there is no printing data in one band, the absolute value of the acceleration / deceleration speed is not reduced either. This is because since there is no discharge, there is no chance of the meniscus breaking, and the meniscus is less likely to break even if the pressure in the recording head is relatively high to a certain extent. For bands 27 to 65, the absolute value of the acceleration during acceleration / deceleration in the first region is made smaller by multiplying the absolute value of the acceleration during acceleration / deceleration in the second region, which is 20.0 m / s / s, by a ratio set in advance according to the duty. For example, for bands 27 to 39, it becomes 20.0 × 0.93 = 18.6 m / s / s. As a result, a good image could be obtained without the occurrence of printing streaks for all bands. In addition, although the reference line of the pressure fluctuation increased by up to about 30 mmAq at most, the increase was suppressed to a level that could be sufficiently tolerated even by a recording head without a damper. Regarding throughput, since the minimum necessary acceleration / deceleration reduction was suppressed, it was possible to make it almost equivalent to Comparative Example 2 where all the acceleration / deceleration speeds were 20.0 mm / s / s, and a high-speed and high-quality image could be output.

[0054]

Table 1

[0055] <Example 9> In Example 9, image data is also input for colors other than black (Bk). As shown in Table 2, in addition to black (Bk), image data using cyan (C), magenta (M), and yellow (Y) was prepared. Table 2 is an excerpt of a table of the image data in a certain band among the A1 size image data and the ratio of the acceleration and deceleration speeds corresponding thereto. When comparing the average duty of each color in a certain band, the color with the highest average duty is cyan (C) at 20%. On the other hand, the color with the lowest average duty is yellow (Y), which is 0%. As described in this specification, a higher average printing duty per band is advantageous for non-ejection because the inside of the recording head moves in the depressurization direction due to ejection. Therefore, when comparing each color in Table 2, the color that is most disadvantageous for non-ejection is yellow (Y) with an average duty of 0% per band. However, as also described in Example 8, when there is no ejection at all, since there is no trigger for the meniscus to break, it can withstand a certain degree of high pressure. From the above, the color that is most disadvantageous for non-ejection in Table 2 is magenta (M) with an average duty of 3%. This example adopted the ratio of the acceleration and deceleration speeds corresponding to 3% of magenta (M), which has the smallest average duty among the colors to be ejected, and set the absolute value of the acceleration during acceleration and deceleration in the first region to 0.62 times the absolute value of the acceleration during acceleration and deceleration in the second region. As a result, no non-ejection occurred for any color, and a good image without printing streaks was obtained.

[0056] Also, as Comparative Example 5, the image results when adopting the ratio of black (Bk) with an average duty of 10% per band are also described in Table 4. As a result, no printing streaks were observed in black (Bk), cyan (C), and yellow (Y), but non-ejection occurred for magenta (M) and printing streaks were confirmed.

[0057]

Table 2

[0058] <Example 10> In Example 10, a recording device with a configuration equipped with a thermometer capable of measuring the temperature inside the recording device is used. In Examples 1 to 9, the printing environment temperature was set to 25°C, which was raised to 40°C and the same verification was performed. The temperature of the ink changes depending on the printing environment temperature. The higher the temperature of the ink, the lower the viscosity. Therefore, when the same inertial force is generated on the ink in the supply tube, the ink is more likely to move. Actually, in this example, the viscosity of black (Bk) at 25°C was 3.5 mPa·s, and when heated to 40°C, the viscosity changed to 2.4 mP·s. Based on the above measurement results, a table shown in Table 3 was created to suppress the increase in the reference value of pressure fluctuation for each printing environment temperature and recorded in the ROM 402 of the recording device. As shown in FIG. 11, the printing environment temperature is measured using the temperature and humidity sensor provided in the recording device, and after collating with the table in Table 3, the absolute values of the acceleration during acceleration and deceleration at the first acceleration rate are reduced by the ratio of the acceleration rate set. The image data is image data using only black (Bk), and the average duty per band is 5%. Since the printing environment temperature was set to 40°C, the absolute values of the acceleration during acceleration and deceleration in the first region were 0.42 times the absolute values of the acceleration during acceleration and deceleration in the second region. As a result, the printing streaks were not visible and the throughput was 95 seconds.

[0059]

Table 3

[0060] <Example 11> In Examples 11 to 13, regarding the setting of the acceleration rate, the length L from the bent portion of the supply tube 4 to the connection portion 25 of the recording head 3 is considered. As shown in FIGS. 6 and 6, the longer the length L, the greater the pressure fluctuation. Therefore, the greater the difference in the length L between the first region and the second region, the greater the increase in the reference value of the pressure fluctuation.

[0061] In this embodiment, the length from the bent portion to the recording head connection portion when the carriage speed is 0 in the first region and the second region, that is, when the recording head is positioned at both outermost ends in the recording apparatus, was defined as L. Specifically, as shown in FIG. 13, the length from the bent portion of the supply tube 4 to the recording head connection portion when the carriage reaches the right side in the recording apparatus was defined as the length L1 in the first region. Also, the length from the bent portion of the supply tube 4 to the connection portion 25 of the recording head 3 when the carriage reaches the left side in the recording apparatus was defined as the length L2 in the second region. In addition, when the absolute value of the acceleration during acceleration and deceleration in the first region was dv1 / dt and the absolute value of the acceleration during acceleration and deceleration in the second region was dv2 / dt, the absolute value of the acceleration was set so as to satisfy the following relationship.

[0062]

Equation

[0063] In addition, when L1 and L2 were measured in this embodiment, L1 was 300 mm and L2 was 50 mm. From the above, when the absolute value of the acceleration during acceleration and deceleration in the second region was set to 20.0 m / s / s, the absolute value of the acceleration during acceleration and deceleration in the first region was determined to be 3.3 m / s / s. When printing was started with this set value of acceleration and deceleration, the reference value of the pressure fluctuation became approximately 0 mmAq and the printing result was "no ejection failure", confirming that it was effective. Also, the throughput was 105 seconds.

[0064] <Example 12> In this embodiment, the length L from the bent portion of the supply tube 4 to the connection portion 25 of the recording head 3 is set as the length at the end of each acceleration region and the start of each deceleration region. That is, it is the length in a state where the acceleration or deceleration is 0 m / s / s and the carriage 2 has a speed in each acceleration / deceleration region. In this embodiment, the length in the first region is denoted as L1', and the length in the second region is denoted as L2'. L1' and L2' are illustrated in FIG. 14. When expressing L1' and L2' using L1 and L2 of Example 11 and the absolute value of the acceleration dv2 / dt during acceleration and deceleration in the second region, it can be represented by the following formula.

[0065] [Number]

[0066] Using the obtained L1' and L2', the absolute value of the acceleration dv1 / dt during acceleration and deceleration in the first region was expressed by the following formula.

[0067] [Number]

[0068] When measuring L1' and L2' in this embodiment, L1' was 82 mm and L2' was 268 mm. Therefore, based on the relationship of formula (4), the absolute value of the acceleration during acceleration and deceleration in the first region was set to 6.1 m / s / s, which is about 0.3 times the absolute value of the acceleration during acceleration and deceleration in the second region of 20.0 m / s / s. When starting printing with the above settings, no printing streaks occurred as in Example 11, and in addition, the throughput was 99 seconds, which was faster. However, compared to Example 11, since the absolute value of the acceleration during acceleration and deceleration in the first region became larger than the absolute value of the acceleration during acceleration and deceleration in the second region, although no non-ejection occurred, the reference value of the pressure fluctuation slightly increased to 25 mmAq.

[0069] [Example 13] In this embodiment, the length L from the bent portion to the connection portion 25 of the recording head 3 is determined in consideration of the ink flow direction. In this embodiment, as shown in FIG. 15, the supply tube 4 has two bent portions, i.e., a bent portion 11 and a bent portion 13, which correspond to the upstream bent portions in the direction in which the ink flows from the main tank 9 to the recording head 3. The supply tube 4 is routed in a winding manner. When the recording head 3 is located on the downstream side, the supply tube 4 is routed in a winding manner so as to have bent portions 12 and 14.

[0070] In this case, in the first region, the direction of the inertial force acting on the ink in the supply tube 4 between the bent portion 11 and the bent portion 12 is opposite to the direction of the inertial force acting on the ink in the supply tube 4 between the bent portion 12 and the connection portion 25 of the recording head 3.

[0071] Therefore, with respect to the pressure in the recording head 3, the inertial force acting on the ink in the supply tube 4 between the bent portion 11 and the bent portion 12 acts toward the positive pressure side. And the inertial force acting on the ink in the supply tube 4 between the bent portion 12 and the head connection portion acts toward the negative pressure side. Similarly, in the second region, forces in opposite directions act. Thus, with respect to the pressure fluctuation, in the first region, the length obtained by subtracting the length L11 from the bent portion 12 to the head connection portion from the supply tube length L10 between the bent portion 11 and the bent portion 12 is defined as L1''. In this embodiment, the above length is not the actual supply tube length, but the length projected in the moving direction of the carriage 2. Similarly, with respect to L2'', the length L20 obtained by projecting the supply tube 4 from the bent portion 13 to the bent portion 14 in the moving direction of the carriage is subtracted from the length L21 obtained by projecting the supply tube 4 from the bent portion 14 to the connection portion 25 of the recording head 3 in the moving direction of the carriage 2. From the above, the absolute value dv1 / dt of the acceleration during acceleration and deceleration in the first region in this embodiment is 4.0 m / s / s obtained from the following formula.

[0072]

Equation

[0073] During printing, the reference value of the pressure fluctuation shifted to about 5 mmAq on the positive pressure side, but no printing streaks were observed and it was determined that there was no non-ejection. The throughput was 103 seconds. From this, it can be seen that even in the case of the meandering of the supply tube having two or more bending portions as in this embodiment, deterioration of the image quality can be suppressed by controlling the acceleration and deceleration rates.

[0074] <Comparative Example 1> As shown in Table 4 as Comparative Example 1, the case where the absolute values of the acceleration and deceleration in the first region and the second region were all set to 20.0 m / s / s was verified. Then, the reference value of the pressure fluctuation increased by about 75 mmAq, and printing streaks occurred.

[0075] <Comparative Example 2> Next, as Comparative Example 2, under the same conditions as Comparative Example 1, the average duty per band of only the black (Bk) of the image data was set to 80%. The printing result was no non-ejection, but this was because the pressure in the recording head decreased due to ejection and the reference value of the pressure fluctuation did not shift. When the printing duty is low as in Comparative Example 1, printing streaks occur.

[0076] <Comparative Example 3> In Comparative Example 3, the absolute values of all accelerations and decelerations were set to 30 m / s / s. In addition, a damper device for dynamic pressure absorption as shown in FIG. 12 was provided in the recording head. As a result, although the damper device was installed, non-ejection occurred and printing streaks were observed in the image. Even though the damper device for absorbing dynamic pressure was installed, the meniscus of the nozzle was broken due to pressure exceeding the volume.

[0077] <Comparative Example 4> In Comparative Example 4, the absolute value of the acceleration during acceleration and deceleration in the first acceleration region was set to 13.0 m / s / s, and the absolute value of the acceleration during acceleration and deceleration in the second acceleration region was set to 10.0 m / s / s. Although the acceleration and deceleration were overall reduced, the absolute value of the acceleration and deceleration in the first region was relatively larger than the absolute value of the acceleration and deceleration in the second region. As a result, the reference value of the pressure fluctuation in the recording head increased significantly, and non-ejection occurred. From this, it was found that an effect was produced depending on the relative relationship between the acceleration or deceleration in the first region and the acceleration or deceleration in the second region.

[0078] <Comparative Example 5> In Comparative Example 5, the image data also used in Example 9 was input, and the acceleration and deceleration in the first region were set to 18.0 m / s / s in accordance with the average duty per band of black (Bk). As a result, for black (Bk), the average duty was high and the image was good, but for magenta (M) with a low average duty, print streaks due to non-ejection occurred.

[0079] The following is a table summarizing the examination conditions of the examples and comparative examples.

[0080]

Table 4

[0081] The device configuration described above is merely an example of the device configuration for realizing the present invention. Needless to say, the present invention can be applied even if, for example, the size of the recording device, the number of recording inks, the number of supply tubes, the number of ejection element substrates, etc. are different. Also, in this embodiment, a configuration for controlling the carriage speed using the average duty was described, but in addition to the average duty, the carriage speed may be determined using the total dot count per band, the total ink amount to be ejected, etc.

Explanation of Reference Signs

[0082] 2 Carriage 3 Recording head 4 Supply tube 7 Ink 8 Supply System P Recording Medium

Claims

1. An ink tank for storing ink, A recording head having nozzles for ejecting ink based on image data, A carriage mounted with the recording head and reciprocating in a predetermined direction, Carriage control means for moving the carriage, A supply tube connected to the recording head and the ink tank, supplying ink from the ink tank into the recording head, and having a bent portion that moves as the carriage moves in the predetermined direction, Obtaining means for obtaining information regarding the amount of ink ejected onto one band, which is an area where the carriage can move and record in one direction of the predetermined direction based on the image data, A recording apparatus comprising: In a region where the speed changes due to acceleration or deceleration of the carriage in the moving region of the carriage, a region where the pressure changes in a direction in which the negative pressure in the recording head weakens is defined as a first region, and a region where the pressure changes in a direction in which the negative pressure in the recording head strengthens in the acceleration / deceleration region of the carriage is defined as a second region. When this is the case, The carriage control means moves the carriage such that an absolute value of an acceleration of the carriage that accelerates or decelerates in the first region is smaller than an absolute value of an acceleration of the carriage that accelerates or decelerates in the second region, The carriage control means determines whether to move the carriage such that an absolute value of an acceleration of the carriage in the first region is smaller than an absolute value of an acceleration of the carriage in the second region, or to make the absolute value of an acceleration of the carriage in the first region the same as the absolute value of an acceleration of the carriage in the second region, according to the amount of ink ejected onto the one band indicated by the information obtained by the obtaining means, and moves the carriage based on the determination. A recording apparatus characterized by this.

2. When the amount of ink to be ejected onto the one band indicated by the information acquired by the carriage control means is less than a predetermined amount, the carriage is moved so that the absolute value of the acceleration of the carriage in the first region is less than the absolute value of the acceleration of the carriage in the second region. When the amount of ink to be ejected onto the region indicated by the information acquired by the acquisition means is equal to or greater than the predetermined amount, the carriage is moved so that the absolute value of the acceleration of the carriage in the first region is the same as the absolute value of the acceleration of the carriage in the second region. The recording apparatus according to claim 1, characterized in that.

3. The recording apparatus according to claim 2, characterized in that the predetermined amount is an amount equal to or more than half of the maximum amount that the recording head can eject onto the one band.

4. When the amount of ink to be ejected onto the one band indicated by the information acquired by the carriage control means is not zero and is less than the predetermined amount, the carriage is moved so that the absolute value of the acceleration of the carriage in the first region is less than the absolute value of the acceleration of the carriage in the second region. When the amount of ink to be ejected onto the region indicated by the information acquired by the acquisition means is zero and is less than the predetermined amount, the carriage is moved so that the absolute value of the acceleration of the carriage in the first region is the same as the absolute value of the acceleration of the carriage in the second region. The recording apparatus according to claim 2 or 3, characterized in that.

5. The recording head is capable of ejecting inks of a plurality of colors, acquisition means for acquiring information regarding the amount of ink to be ejected onto the one band for each of the plurality of colors based on the image data; The recording apparatus according to any one of claims 1 to 4, characterized in that the carriage control means controls the speed of movement of the carriage based on the amount of ink ejected most among the amounts of ink of each color to be ejected onto the region indicated by the information acquired by the acquisition means.

6. The recording apparatus according to any one of claims 1 to 5, characterized in that the information acquired by the acquisition means is an average value of the amount of ink to be ejected onto the one band.

7. The carriage control means moves the carriage such that the absolute value of the acceleration of the carriage during acceleration and deceleration in the first region is smaller than the absolute value of the acceleration of the carriage during acceleration and deceleration in the second region. The recording apparatus according to any one of claims 1 to 6.

8. It has measuring means capable of measuring the temperature inside the recording apparatus, The carriage control means controls the carriage speed based on the temperature measured by the measuring means. The recording apparatus according to any one of claims 1 to 7.

9. When the temperature measured by the measuring means is a second temperature higher than the first temperature rather than the first temperature, the carriage control means makes the absolute value of the acceleration in the second region with respect to the absolute value of the acceleration in the first region larger so as to control the carriage. The recording apparatus according to claim 8.

10. The carriage control means controls the carriage speed based on the length from the bent portion of the supply tube to the connection portion of the recording head when the carriage starts acceleration and deceleration. The recording apparatus according to any one of claims 1 to 9.

11. The recording head performs recording on a recording medium by discharging ink from nozzles based on image data while being moved in a predetermined direction by a carriage, A recording method of supplying ink from an ink tank storing ink to the recording head through a supply tube having a bent portion that moves as the carriage moves, Based on the image data, information regarding the amount of ink discharged per band, which is a recordable region where the carriage moves in one direction in the predetermined direction, is obtained, When a region where the pressure changes in a direction in which the negative pressure in the recording head weakens in an acceleration / deceleration region where the speed of the carriage changes due to acceleration or deceleration of the carriage in the moving region of the carriage is defined as the first region, and a region where the pressure changes in a direction in which the negative pressure in the recording head strengthens in the acceleration / deceleration region of the carriage is defined as the second region, The carriage is moved such that the absolute value of at least one of the accelerations during acceleration or deceleration of the carriage in the first region is smaller than the absolute value of the acceleration during acceleration or deceleration of the carriage in the second region. According to the amount of ink ejected onto the one band indicated by the obtained information, move the carriage so that the absolute value of the acceleration of the carriage in the first region is smaller than the absolute value of the acceleration of the carriage in the second region, or make the absolute value of the acceleration of the carriage in the first region the same as the absolute value of the acceleration of the carriage in the second region, and move the carriage based on the determination. A recording method characterized by this.

Images