JP2006103209A - Inkjet recording apparatus and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a deterioration in image quality due to thickening of ink with time. <P>SOLUTION: After moving a carriage 504 to a home position to effect preliminary ejection, the carriage is moved by a distance L1 to an image formation starting point to start recording an image. In this case, judgement is made to ensure whether there is any ejection port which elapses a specified time without ejection after effecting preliminary ejection, prior to start forming an image. If there is any such a port, the first half path is recorded without using the ejection port for recording. If there is none, all the ejection ports are used to perform recording. In the former case, the carriage is moved to a preliminary ejection position 502 after completion of recording to perform preliminary ejection, while using the ejection port not used for the first half path is used to perform recording the second half path. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus such as an ink jet printer that records (prints) an image by ejecting ink onto a recording material (recording medium) by recording means such as a recording head.

  A recording device having functions such as a printer, a copying machine, a facsimile, or a recording device used as an output device such as a composite electronic device including a computer or a word processor or a workstation is based on image information (including character information). Thus, an image (including characters and the like) is recorded on a recording medium such as paper or a plastic thin plate. Note that in this specification, forming an image such as a character, graphic, or photograph on a print medium such as paper with a color material such as ink (which may include a colorless coating material) is referred to as recording. Such a recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, an electrophotographic type, and the like according to a recording method. Among these recording apparatuses, an ink jet recording apparatus (ink jet recording apparatus) performs recording by ejecting ink from a recording means (recording head) to a recording medium, and has higher definition than other recording systems. It has the excellent characteristics of being easy to make, high speed, excellent quietness, and inexpensive. In order to improve the recording speed, the ink jet recording apparatus uses a plurality of ink discharge ports (ink discharge portions) and a plurality of liquid paths integrated as a recording head in which a plurality of recording elements are integrated, Generally, a plurality of the recording heads are provided. These recording heads are placed on a carriage that can reciprocate in the main scanning direction. The recording medium can be conveyed in a direction substantially orthogonal to the main scanning direction.

Prior to the start of recording, when a recording start command is received, the carriage at the home position performs recording by ejecting ink in accordance with an image from a plurality of ejection ports on the recording head while moving in the main scanning direction. When recording for forming an image is completed up to the end of the recording medium located on the side opposite to the home position, the carriage returns to the original home position and repeats recording while moving the carriage in the main scanning direction again. At this time, an image may be formed when the carriage returns to the home position in the backward direction. When recording is performed on a recording medium in this manner, if ink is ejected from an ink ejection port that has not been used for recording for a certain period of time, ink components such as a solvent from the ink ejection port can be removed while it is not being used. Evaporation increases the viscosity of the ink (this is called ink thickening), resulting in an increase in ink density and ejection failure. In order to prevent this phenomenon, the recording head recovery operation such as preliminary ink ejection and suction is performed at the home position every time a predetermined time elapses (see, for example, Patent Document 1).
JP-A-06-008470

  On the other hand, in order to achieve high image quality in an inkjet recording apparatus, there is an approach of reducing the graininess of an image by reducing the size of ink droplets ejected from an ink ejection port. If the ink droplets are made smaller, the proportion of the amount of ink evaporated from the ink ejection port to the amount of ejected ink droplets increases. For this reason, the ink thickening speed is increased, and the ink density is increased and ejection failure is likely to occur. For this reason, in a high-quality inkjet recording apparatus in which ink droplets are reduced, a phenomenon has occurred in which the ink viscosity increases in a time shorter than the time for which the recording head performs one main scan, making it unsuitable for recording. For this reason, some images are formed because there are ejection openings that are not used for a time exceeding the allowable time for non-ejection of ink (the time until the fresh ink becomes unsuitable for recording due to evaporation or the like). The quality of the image sometimes deteriorated. Such a phenomenon cannot be prevented even if the recovery operation of the recording head is performed for each scanning because the allowable time of non-ejection of ink is shorter than the scanning time of one time of the recording head.

  The present invention has been made in view of the above-described conventional example. Even when the ink deterioration time is shorter than the time required for the main scanning by the recording head in the serial recording apparatus, the image quality is deteriorated due to the ink thickening. An object of the present invention is to provide an ink jet recording apparatus and a recording method capable of preventing the above-described problem.

  In order to achieve the above object, the present invention comprises the following arrangement.

An inkjet recording apparatus that performs a recording scan in which ink is ejected from a plurality of ejection ports arranged in a direction different from the main scanning direction while performing a main scanning of the recording head relative to the recording medium, and recording on the recording medium.
In the main scanning direction, a preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of the recording area of the recording head by the recording head; Determining means for determining, for each discharge port of the recording head, whether or not an ink discharge interval at which ink is discharged next after discharge is within a predetermined value;
In the first recording scan, recording is performed using an ejection port whose ink ejection interval is determined to be within a predetermined value by the determination unit, and preliminary ejection is performed at the preliminary ejection unit located near the end of the first recording scan. In the subsequent second recording scan, scanning is performed in the direction opposite to that of the first recording scan, and recording is performed using the ejection port determined by the determination means that the ink ejection interval is not within a predetermined value. And a recording control means for performing the above.

Alternatively, an inkjet recording apparatus that performs a recording scan in which ink is ejected from a plurality of ejection ports arranged in a direction different from the main scanning direction while the recording head is relatively scanned with respect to the recording medium. And
A preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of a recording area of the recording head with respect to the recording medium by the main scanning direction;
In the recording scan in the main scanning direction of the recording head, it is determined for each ejection port of the recording head whether the ink ejection interval at which ink is ejected first and then the ink is ejected next is within a predetermined value. Determination means to perform,
In the first recording scan, recording is performed using the ejection port in which the ink ejection interval is determined to be within a predetermined value by the determination unit, and after the first recording scan is completed, preliminary ejection is performed in the preliminary ejection unit. In the second recording scan, the recording head is moved at a speed higher than that of the first recording scan, and then the determination unit is used to determine that the ink discharge interval is not within a predetermined value. And a recording control means for performing recording.

  According to the present invention, the allowable time for non-ejection of ink until the quality of the ink becomes unsuitable for recording is shorter than the time required for the main scanning by the recording head in the serial recording apparatus. However, there is an effect that the deterioration of the image quality due to the ink thickening can be prevented.

  Also, during recording scanning, when recording an image where the ink discharge interval is longer than the ink non-discharge allowable time, the recording is temporarily performed without using the discharge port that may have deteriorated ink characteristics. For the ejection port where the ink characteristics may be deteriorated, an image is formed by rescanning so that the image can be recorded within the ink non-ejection allowable time.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment described below, a recording apparatus using a recording head according to an ink jet method will be described as an example.

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and graphics, but also for human beings to be perceived visually, regardless of significance. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

<Description of Inkjet Recording Apparatus (FIG. 10)>
FIG. 10 is an external perspective view showing an outline of the configuration of the ink jet recording apparatus 1 which is a typical embodiment of the present invention. As shown in FIG. 10, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) transmits a driving force generated by a carriage motor M1 to a carriage 2 on which a recording head 3 that performs recording by discharging ink according to an ink jet system is mounted. 4, the carriage 2 is reciprocated in the direction of arrow A, and for example, a recording medium P such as recording paper is fed through a paper feeding mechanism 5 and conveyed to a recording position. Recording is performed by ejecting ink onto the recording medium P.

  Further, in order to maintain the state of the recording head 3 satisfactorily, the carriage 2 is moved to the position of the recovery device 10 and the ejection recovery process of the recording head 3 is performed intermittently. In addition, the recording apparatus according to the present embodiment is configured so that the preliminary ejection position 23 that allows preliminary ejection other than the home position of the recovery apparatus 10 is within the recording scanning range by the carriage and sandwiches the recording area with respect to the recording medium. 10 at the opposite end. As a result, a recovery operation (preliminary ejection) can be performed at the preliminary ejection position 23. In FIG. 10, the preliminary discharge position 23 is provided at the outer end of the maximum size recording medium. However, for example, an ink absorbing material or the like can be disposed so as to allow preliminary ejection over the entire operation range of the carriage 2 with a width facing the ejection port of the recording head 3. By doing so, even when the width of the recording medium to be recorded is shorter than the maximum width, preliminary ejection can be performed with the immediate outer side of the recording medium as the preliminary ejection position. Preliminary ejection refers to ejecting ink droplets that do not contribute to image formation for the purpose of refilling fresh ink, not for recording purposes, with the ink inside the recording head. The preliminary discharge position is executed.

  In addition to mounting the recording head 3 on the carriage 2 of the recording apparatus 1, an ink cartridge 6 for storing ink to be supplied to the recording head 3 is mounted. The ink cartridge 6 is detachable from the carriage 2.

  The recording apparatus 1 shown in FIG. 10 is capable of color recording. For this reason, the carriage 2 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. An ink cartridge is installed. These four ink cartridges are detachable independently.

  Now, the carriage 2 and the recording head 3 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 3 applies energy according to a recording signal to selectively eject ink from a plurality of ejection ports for recording. In particular, the recording head 3 of this embodiment employs an ink jet system that ejects ink using thermal energy, and includes an electrothermal transducer to generate thermal energy, which is applied to the electrothermal transducer. Electric energy is converted into thermal energy, and ink is ejected from the ejection port by utilizing pressure changes caused by bubble growth and contraction caused by film boiling caused by applying the thermal energy to the ink. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  As shown in FIG. 10, the carriage 2 is connected to a part of the driving belt 7 of the transmission mechanism 4 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 13. It is guided and supported freely. Accordingly, the carriage 2 reciprocates along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 is provided for indicating the absolute position of the carriage 2 along the direction of movement of the carriage 2 (the direction of arrow A). In this embodiment, the scale 8 uses a transparent PET film with black bars printed at a necessary pitch, one of which is fixed to the chassis 9 and the other is supported by a leaf spring (not shown). Yes.

  Further, the recording apparatus 1 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 3 is formed, and the recording head 3 is driven by the driving force of the carriage motor M1. At the same time as the carriage 2 loaded with is reciprocated, a recording signal is given to the recording head 3 to discharge ink, whereby recording is performed over the entire width of the recording medium P conveyed on the platen.

  Further, in FIG. 10, 14 is a transport roller driven by a transport motor M2 to transport the recording medium P, 15 is a pinch roller that abuts the recording medium P against the transport roller 14 by a spring (not shown), and 16 is a pinch. A pinch roller holder 17 that rotatably supports the roller 15 is a conveyance roller gear fixed to one end of the conveyance roller 14. Then, the conveyance roller 14 is driven by the rotation of the conveyance motor M2 transmitted to the conveyance roller gear 17 via an intermediate gear (not shown).

  Further, reference numeral 20 denotes a discharge roller for discharging the recording medium P on which an image is formed by the recording head 3 to the outside of the recording apparatus, and is driven by transmitting the rotation of the transport motor M2. . The discharge roller 20 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). Reference numeral 22 denotes a spur holder that rotatably supports the spur roller.

  Furthermore, as shown in FIG. 10, the recording apparatus 1 includes a desired position (for example, a home position) outside the reciprocal movement range (outside the recording area) for the recording operation of the carriage 2 on which the recording head 3 is mounted. A recovery device 10 that performs a recovery operation for maintaining a good discharge state from the recording head 3 is disposed at a position corresponding to the position).

  The recovery device 10 includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3, and interlocks with the capping of the ejection port surface by the capping mechanism 11. Ink recovery such as forcibly discharging ink from the discharge port by suction means (suction pump or the like) in the recovery device, thereby removing ink or bubbles having increased viscosity in the ink flow path of the recording head 3 Process. Of course, it is also possible to perform preliminary ejection by moving the recording head 3 to the position of the recovery device 10.

  Further, during a non-recording operation or the like, the ejection head surface of the recording head 3 is capped by the capping mechanism 11 (the cap is brought into contact with the ejection port surface) to protect the recording head 3 and to evaporate or dry the ink. Can be prevented. On the other hand, the wiping mechanism 12 is disposed in the vicinity of the capping mechanism 11 and wipes off dirt such as ink droplets and dust adhering to the discharge port surface of the recording head 3. The capping mechanism 11 and the wiping mechanism 12 can keep the ink ejection state of the recording head 3 normal.

  FIG. 1 schematically shows a configuration of a printer unit when recording on a recording sheet with a recording head. Since it is schematically shown, there are some differences from the configuration of FIG. 10, but it is intended to make the recording principle easier to see and does not affect the essence of the invention. In FIG. 1, reference numeral 101 denotes an ink cartridge. These are composed of a recording head 102 having an ink tank filled with four color inks, black, cyan, magenta, and yellow, and an ejection port array for ejecting each color ink.

  FIG. 2 shows the state of the discharge ports arranged on the recording head from the Z direction in FIG. Reference numeral 201 denotes a plurality of ejection openings arranged on the recording head 102. The interval between the ejection openings is 1 / N inch (about 1 / 2.5 N centimeter) in FIG. 2, but N = 300 or 600 in an actual printing apparatus. The recording head 102 includes a plurality of ejection port arrays in which a plurality of ejection ports as shown in FIG. 2 are arranged, and a plurality of types of ink are ejected from the respective ejection port arrays. Returning to FIG. 1, reference numeral 103 denotes a paper feed roller that rotates in the direction of the arrow in the figure while holding the recording medium P together with the auxiliary roller 104, and feeds the recording medium P in the Y direction as needed. Reference numeral 105 denotes a paper feed roller that feeds the recording medium P and plays the role of suppressing the recording medium P as in the case of 103 and 104. A carriage 106 supports four ink cartridges and moves them together with recording. When recording is not being performed, or when performing a recovery operation of the recording head or the like, the apparatus stands by at the home position h indicated by a dotted line in the drawing. A recovery device is disposed in the vicinity of the home position h, and a preliminary discharge position 107 including a preliminary discharge receiving portion is provided on the opposite side across the recording medium.

<Control Configuration of Recording Apparatus (FIG. 3)>
FIG. 3 is a block diagram showing a control configuration of the ink jet recording apparatus of FIGS. 1 and 10 according to an embodiment of the present invention. 3 includes software processing means such as an image input unit 303 that accesses the main bus line 305, an image signal processing unit 304 corresponding to the image input unit 303, and a central control unit CPU300, an operation unit 306, and a recovery system control circuit 307. These are roughly divided into hardware processing means such as a head temperature control circuit 314, a head drive control circuit 315, a carriage drive control circuit 316 in the main scanning direction, and a paper feed control circuit 317 in the sub scanning direction.

  The CPU 300 has a normal ROM (Read Only Memory) 301 and a RAM (Random Access Memory) 302, and gives an appropriate recording condition to input information to drive the recording head 313 to perform recording. A program for executing a printhead recovery sequence is stored in the RAM 302 in advance, and the recovery conditions (timing, position, etc.) such as preliminary ejection conditions are transmitted to the recovery system control circuit 307 as necessary. The CPU 300 controls the carriage drive control circuit 316, the recording head 313, the heat retaining heater, and the like. Further, the RAM 302 stores information indicating whether or not there is an ejection port whose ejection interval is equal to or greater than the ejection allowable interval at the time of recording scanning, which will be described later. This information may be stored for each discharge port, and a predetermined number of discharge ports are grouped into one group to determine whether or not there are discharge ports whose discharge intervals are equal to or greater than the discharge allowable interval. The information shown may be stored. The recovery system motor 308 drives the recording head 313 and the cleaning blade 309, the cap 310, and the suction pump 311 that face and separate from the recording head 313 as described above. The head drive control circuit 315 executes the drive conditions of the ink ejection electrothermal converter of the recording head 313, and causes the recording head 313 to perform normal preliminary ejection and recording ink ejection.

On the other hand, a heat retention heater may be provided on the head substrate on which the electrothermal transducer for ink ejection of the recording head 313 is provided, and the ink temperature in the recording head is heated and adjusted to a desired set temperature. Can do. Similarly, the diode sensor 312 is provided on the head substrate, and is used to measure a substantial ink temperature inside the recording head. Similarly, the diode sensor 312 may be provided outside the substrate or in the vicinity of the periphery of the recording head.
<Recording Operation of the Present Invention>
A first embodiment of the present invention based on the above apparatus configuration will be described below. In the first embodiment of the present invention, four recording heads each having one ink discharge port array shown in FIG. 2 are provided, and each recording head discharges black, cyan, magenta, and yellow ink. Each recording head is configured so that the number of ejection ports is L = 256, the interval between ejection ports is 1/600 inch (about 1/240 cm), and the recording pixel density is 600 dpi (about 240 dots / cm). ing. Further, the ejection amount from each recording head is configured so that about 2 pl of ink droplets can be ejected per droplet, and the ejection frequency for stably ejecting these ink droplets is 24 KHz. . The speed in the main scanning direction of the carriage equipped with this recording head is 20 inches / second (about 50 centimeters / second) when ink droplets are recorded at a density of 1200 dpi (about 480 dots / cm) in the main scanning direction. It becomes.

  In the first embodiment of the present invention, a preliminary ejection position 107 for receiving ink droplets not used for recording is provided at a position opposite to the position of the home position (h) in FIG. 1 via the recording medium. The length of the recording medium in the main scanning direction is 8 inches (about 20 centimeters).

  FIG. 4 is a diagram showing the relationship between the time (ejection interval) from the time when ink is ejected from a certain ejection port to the time of ejection again and the ink ejection state in the recording apparatus of the present embodiment. In the ink ejection state, “×” indicates a state in which the ink droplet landing position is disturbed due to the effect of ink thickening or a color change occurs due to an increase in ink density, and “△” indicates that the ink droplet landing position is not disturbed. Indicates a state in which the color changes slightly due to an increase in ink density, and “◯” indicates a state in which the landing position of the ink droplet does not change and the color does not change due to an increase in ink density. It can be seen from FIG. 4 that the ink discharge interval is 0.6 (seconds) or more, “×”, 0.5 (seconds) “Δ”, and 0.4 (seconds) or less “◯”. Therefore, in this embodiment, image recording is controlled so that the upper limit of the ink discharge interval is 0.4 seconds. The upper limit of this ink discharge interval is called the discharge allowable interval. FIG. 4 is an example based on the characteristics of the ink used in the recording apparatus of the present embodiment, and differs from FIG. 4 if the ink composition is different from that of the present embodiment or the structure of the recording head is different. It becomes a table. However, the point that the allowable discharge interval is given from the correspondence table between the ink characteristics and the allowable discharge interval is the same.

  FIG. 5 is a diagram showing the positional relationship that the carriage scans in the present embodiment. The carriage rising time required for the carriage to scan a distance L1 of 1 inch from the position of the home position 501 (home position h in FIG. 1) to the end of the recording medium 503 is 0.15 (seconds). The time required for the carriage to scan the length L2 (8 inches in this example) of the recording medium 503 in the main scanning direction is 8 (inch) / 20 (inch / second) when printing is performed at a speed of 20 inches / second. Seconds) = 0.4 (seconds). The carriage fall time required for the carriage to scan the distance L3 of 1 inch from the end of the recording medium 503 to the preliminary ejection position 502 is 0.15 (seconds).

  From the relationship between the discharge time from the previous discharge shown in FIG. 4 (discharge interval) and the discharge state, the quality (or deterioration) of the formed image is reduced unless the discharge interval is within 0.4 (seconds). cause. Therefore, even if preliminary ejection is performed at the home position 501 and printing is started in the main scanning direction, 0.15 (seconds) +0.4 (seconds) = 0.55 to finish scanning the area of the recording medium 503. (Seconds) is required. For this reason, an ejection failure occurs at an ink ejection port having image data only in the latter half of the main scanning direction of the recording medium, that is, an ejection port whose ejection interval is longer than the allowable ejection interval after preliminary ejection. Specifically, if the first ink droplet cannot be ejected within 0.4−0.15 (seconds) = 0.25 seconds from the end portion on the home position 501 side of the recording medium, there is a possibility of ejection failure. In other words, recording up to a position of 20 (inch / second) × 0.4−0.15 (second) = 5 inch (about 12.5 centimeters) is possible within the allowable discharge interval from the preliminary discharge.

  In the present embodiment, the width of the recording medium is 8 inches, which corresponds to 0.4 seconds in terms of carriage movement time. That is, if ink is ejected at the end of the recording medium on the scanning start side of the carriage, the carriage reaches the other end in the scanning after 0.4 seconds, so no ink was ejected during that time. Even within the allowable discharge interval. For this reason, the discharge interval to be considered is limited to the discharge interval after the preliminary discharge. The case where the ink discharge interval during recording exceeds the allowable discharge interval will be described in a third embodiment.

  FIG. 6 is a diagram for explaining a recording operation in the present embodiment. FIG. 7 is a flowchart for explaining the recording operation in the present embodiment. The flowchart in FIG. 7 is a control procedure executed by the CPU 300 that controls the printing apparatus. It is also a program procedure for causing the CPU 300 to execute the control procedure. In the flowchart shown in FIG. 7, a recording operation in which scanning of a carriage (not shown) on which a recording head is mounted is started from the position of the home position 601 in FIG. . In this specification, an image area refers to an area in which an image is recorded on a recording medium by a single scan of the recording head.

  In step S701 in FIG. 7, the carriage is first moved to the home position, and preliminary ejection is performed from all of the 256 ejection ports for each color. Next, in step S702, the time from the start of preliminary ejection in step S701 to the start of image data recording in the image area A for each ejection port used for recording is a predetermined time (discharge allowable interval). Within, for example, 0.4 seconds. If the conditions are satisfied for all the discharge ports, the process branches to step S703. If even one discharge port does not satisfy the condition, the process branches to step S705. When branching to step S705, the discharge port determined to satisfy the condition and the discharge port determined not to satisfy the condition are stored in an identifiable manner.

  In step S702, based on the bitmap data for each color component of the image area A (referred to as a target image area) to be recorded in one scan to be performed, the first ink ejection is performed at the edge of the recording medium. If 0.25 seconds or more have elapsed from the timing at which recording is to be performed, “No” is determined. When converted into the number of pixels, 0.25 seconds is 24000 (Hz) × 0.25 (seconds) = 6000 dots. Therefore, the determination in step S702 can be realized from the image data by determining whether or not the first recorded dot is more than 6000 dots away from the dot corresponding to the end of the recording medium on the home position side. In this way, the determination in step S702 can be performed by converting the time into a dot position. Such determination of S702 is performed for all of the plurality of ejection openings of the recording head.

  If “Yes” in the determination of step S702, the discharge interval does not exceed the discharge allowable interval for any of the discharge ports. Therefore, in step S703, the recording of the image area A is completed using all the ejection openings used for the recording. In step S704, the carriage is moved in the backward direction to return the carriage to the home position. Thereafter, in order to record the image area B of FIG. 6 as the next image area, the recording medium is conveyed by an amount of 256 dots / 600 dpi in step S708.

  If “No” in the determination in step S702, there is a case where the discharge interval is longer than the discharge allowable interval for any of the discharge ports. Therefore, in step S705, the image area A is recorded in the forward direction using only the ejection port that starts the recording of the image data by performing the first ink ejection within the allowable ejection interval, that is, within 0.4 seconds from the preliminary ejection. To do. The discharge ports used at this time are those stored in the determination in step S702.

  When the recording in the forward direction is completed, next, in step S706, all the 256 ejection openings for each color at the preliminary ejection position 602 (ejection position 23 in FIG. 10) located opposite to the home position with respect to the recording medium. Preliminary discharge is performed from the discharge port. In step S707, the image area A is recorded and completed in the backward direction using the discharge ports not used in step S705. The ejection ports that are not used in step S705 are determined that the time interval from the time when the preliminary ejection is performed in step S702 to the first ink ejection in the image area A is not within the allowable ejection interval (for example, 0.4 seconds). The discharge port. The portion (line) formed on the forward path is not recorded on the return path.

  Thereafter, in order to record the next image area, image area B in FIG. 6, the recording medium is conveyed by an amount of 256 dots / 600 dpi in step S708.

  Then, for the image areas B and C in FIG. 6 or other image areas, the process from step S701 to step S708 is repeated as in the image area A to complete the image.

  As described above, for the ejection port in which the time from when the preliminary ejection as the previous ejection is performed to when the image data is recorded is longer than the time causing the image degradation, the recording is performed in the scanning in the forward direction of the carriage. The image is completed without causing image degradation by performing preliminary ejection at the preliminary ejection position located at the recording start position from the backward direction, and then recording in scanning in the backward direction to complete the image. Can be made.

  In the present embodiment, the case of one-pass printing at the minimum has been described. In the one-pass method, the procedure shown in FIG. 7 is executed for one pass. Therefore, one pass may be divided and recorded on the forward path and the backward path. Even in multi-pass printing, image degradation can be prevented by using a method similar to that of the present embodiment for image data to be printed in the main scanning. Multipass printing is a method of printing one image area by scanning with a plurality of printing heads. In the multi-pass, the recording medium is usually conveyed by a predetermined amount for each scanning, but when this embodiment is applied to the multi-pass, the procedure of FIG. 7 is executed for one pass. Therefore, one pass may be divided and recorded on the forward path and the backward path. In that case, the recording medium is not conveyed between the forward path and the backward path.

  Further, in the present embodiment, based on the one-way recording in which the detection of the presence or absence of the discharge ports that cause image deterioration for forming an image only when recording the forward direction is performed on each discharge port, The present invention is not limited to this, and if the image area can be completed in the forward direction recording, the next image area may be recorded in the backward direction. In that case, the recording may be performed by detecting the presence / absence of ejection that causes image deterioration for forming an image during recording in the backward direction also for each ejection port. With this configuration, the recording speed can be improved by performing reciprocal recording.

  In the present embodiment, the previous ejection is described as the preliminary ejection. However, the present invention is not limited to this, and the previous ejection is used as the ejection used for recording the image data. In the case where it takes longer than the time to cause the image, the image may be completed by the recording scan from the opposite direction after performing the preliminary ejection without performing the recording in the scanning.

<Modification of First Embodiment>
Further, in the present embodiment, in order to eliminate time loss due to the execution of step S702 in FIG. 7, step S702 is first executed before the start of image recording, and then step S701 is performed when performing a recording scan. It can also be configured to execute. By doing so, it is possible to reduce the waste of time in step S702 after the preliminary discharge until the start of recording. As described above, by performing the process of step S702 in advance before the start of image recording, it is possible to reduce the load on the CPU during recording of the recording apparatus. In addition, since the CPU mounted on the recording apparatus can be made inexpensive, the cost can be reduced.

  However, a CPU having a processing capability capable of completing step S702 by executing the process of step S702 in parallel while moving the carriage to the printing position immediately after the preliminary ejection and reaching the recording start position is mounted on the recording apparatus. In that case, the process of step S702 is not a loss.

  Further, in step S702 in FIG. 7, the determination is performed in advance before the image formation. However, the determination may be performed in real time during the image formation. In that case, a non-ejection flag indicating that the ejection interval is equal to or greater than the ejection allowable interval is prepared for each ejection port and set in advance. Then, the recording of the forward path is started, and if the first ejection is performed for each ejection port, the non-ejection flag is reset. However, preliminary discharge is excluded. At the same time, the elapsed time from the preliminary discharge is measured by the CPU, and if the elapsed time has passed the allowable discharge interval, the non-discharge flag is read for the subsequent recording operation and the corresponding non-discharge flag is set. As for, no discharge is performed in the outward path. Then, on the return path, the recording operation is performed in the manner of steps S706 and S707 in FIG.

  In this way, it is not necessary to perform the determination in step S702 for image data in advance, and image formation can be started quickly. In addition, it is easy to determine whether or not each discharge port satisfies the condition of step S702. In this way, by changing the recording operation according to whether or not the discharge interval is equal to or greater than the discharge allowable interval based on the real time, it is possible to achieve higher image quality by forming an image from the discharge port having a good discharge state. It is possible to output a simple image.

  Furthermore, in the present embodiment, it is determined whether or not the discharge interval is equal to or greater than the allowable discharge interval for each of the discharge ports. However, among the inks used for recording, the recording scan with a single discharge allowable interval is performed. In the case where there is ink longer than the time required for this, the present invention is not applied, and the present invention may be applied only to ink whose discharge allowable interval is shorter than the time required for one printing scan. In addition, by storing an appropriate time corresponding to the type of ink and the recording mode in the RAM as the discharge allowable interval, it is possible to reduce ink discharge from the discharge port that causes image deterioration.

  This modification can also be applied to the second to fourth embodiments.

[Second Embodiment]
In the second embodiment of the present invention, a recording head in which the ink discharge port arrays shown in FIG. Also in the second embodiment, as in the first embodiment, ink droplets that are not used for recording at a position opposite to the position of the home position (h) in FIG. A preliminary ejection position for receiving the recording medium is provided, and the recording medium has a width of 8 inches in the main scanning direction. The difference between the present embodiment and the first embodiment is that the discharge interval is managed by time in the first embodiment, but is managed by distance in the present embodiment. Hereinafter, the present embodiment will be described, but this is the essential difference from the first embodiment. In addition to this essential difference, there are descriptions in the first embodiment that are not in the present embodiment for the sake of explanation. However, it should be applied to this embodiment as well as the first embodiment. The configuration of the recording apparatus is as shown in FIGS. 1 to 3 and 10 and is common to the first embodiment.

  FIG. 4 is a diagram showing the relationship between the discharge time and the time from the previous discharge to the discharge in the present embodiment. In the ejection state, “×” indicates a state in which the ink droplet landing position is disturbed due to the effect of ink thickening or a color change occurs due to an increase in ink density, and “△” indicates that the ink droplet landing position is not disturbed. A state in which the color changes slightly due to an increase in the ink density, and “◯” indicates a state in which the landing position of the ink droplet does not change and the color does not change due to the increase in the ink density. As shown in FIG. 4, when the time from the previous discharge to the discharge is 0.6 (seconds) or more, “X”, 0.5 (seconds) “△”, 0.4 (seconds) or less, “○ " This is the same as in the first embodiment.

  FIG. 5 is a diagram showing the positional relationship that the carriage scans in the present embodiment. The carriage rising time required for the carriage to scan the distance L1 of 1 inch from the position of the home position 501 to the end of the recording medium 503 is 0.15 (seconds). The time required for the carriage to scan the distance L2 having a width of 8 inches in the main scanning direction of the recording medium 503 is 8 (inch) / 20 by performing recording at a constant speed of 20 inches / second. (Inch / second) = 0.4 (second). The carriage fall time required for the carriage to scan the distance L3 of 1 inch from the end of the recording medium 503 to the preliminary ejection position 502 is 0.15 (seconds).

  From the relationship between the discharge time from the previous discharge in FIG. 4 and the discharge state, if the time from the previous discharge to the discharge is not within 0.4 (seconds), image deterioration will be caused. In this case, even if preliminary ejection is performed and recording is started in the main scanning direction, the time required to move the scanning distance (L1 + L2) required to finish scanning the recording medium 503 is 0.15 (seconds) +0.4. (Seconds) = 0.55 (seconds) is required, and an ejection failure is caused in an ink ejection port having image data in the latter half of the main scanning direction of the recording medium. The scanning distance that can be scanned within 0.4 (seconds) from the previous ejection to the ejection that does not cause image deterioration is the same as the scanning distance minus 0.4 seconds, with L1 scanning at a carriage rise time of 0.15. The scanning distance that can be moved in 0.25 seconds (0.25 / 0.4) × L2 = 0.625 × 8 = 5 inches. Therefore, the scanning distance after the preliminary ejection is performed is 1 inch + 5 inches = 6 inches. That is, generalizing this, the upper limit of the non-ejection scanning distance after the preliminary ejection is given by L1 + (Tth−T1) × V where the scanning speed is V, the rising time is T1, and the ejection allowable interval is Tth. (Tth−T1) × V is a moving distance when moving at a speed V for a time (Tth−T1).

  As in the first embodiment of the present invention, FIG. 6 is a diagram for explaining a recording operation in the present embodiment. FIG. 8 is a flowchart for explaining the recording operation in this embodiment. FIG. 8 is executed by the CPU 300. First, a recording operation in which a carriage on which a recording head (not shown) in FIG. 6 is mounted performs recording using all ink discharge ports in a minimum of one pass from the position of the home position (601) will be described.

  In step S801 of FIG. 8, first, preliminary discharge is performed from all of the 256 discharge ports of each color at the home position. Next, in step S802, whether or not there is image data within an allowable discharge interval, for example, within 6 inches from the position of the home position where the preliminary discharge was performed in step S801 toward the forward direction for each discharge port used for recording. Make a decision. For example, when the determination in step S802 is performed before recording, the length of 6 inches (about 15 centimeters) can be converted into the number of pixels using the recording density of the recording apparatus (1200 dpi in this example). Since the image area is 5 inches, it corresponds to 6000 dots. Therefore, an ejection port in which no data to be recorded exists from the position of the end portion on the home position side to 6000 dots is determined as an ejection port that does not perform ejection within the ejection allowable interval. If there is even one such outlet, the determination result in step S802 is “No”. If there is none, it will be “Yes”.

  If “Yes” in the determination in step S802, the recording of the image area A is completed using all the ejection ports used for recording in step S803, and the carriage is moved in the backward direction in step S804. Return to home position. After that, in order to record the next image area, image area B in FIG. 6, in step S808, the recording medium is conveyed by an amount of 256 dots / 600 dpi.

  If “No” in the determination in step S802, only discharge ports having image data at a scan allowable distance, for example, a scanning distance within 6 inches from the home position where the preliminary discharge was performed in step S805 in the forward direction. Used to record the image area A in the forward direction. Next, in step S806, preliminary ejection is performed from all of the 256 ejection ports of each color at the preliminary ejection position opposite to the home position, and in step S807, the image area A that was not recorded in step S805. Is not used in step S805, ie, the discharge position where there is no image data in the allowable discharge interval, that is, the scanning distance within 6 inches from the position of the home position where the preliminary discharge is performed in the determination in step S802 toward the forward direction. Using the exit, the image area A that was not recorded in the return direction is recorded and completed.

  Thereafter, in order to record the image area B of FIG. 6 as the next image area, the recording medium is conveyed by an amount of 256 dots / 600 dpi in step S808. Similarly to the image area A, the image areas B and C in FIG. 6 and subsequent image areas are repeated to complete the image by repeating steps S801 to S808.

  As described above, the discharge distance in the forward direction of the carriage is longer than the scanning distance in which the scanning distance from the execution of the preliminary ejection that is the previous ejection to the recording of the image data is longer than the scanning distance that requires time to cause image degradation. The image is deteriorated by performing the preliminary ejection at the preliminary ejection position located at the recording start position from the backward direction without performing the recording in the scanning, and then completing the image by recording in the scanning in the backward direction. The image can be completed without any problems.

<Modification of Second Embodiment>

Further, in step S802 in FIG. 8, the determination is performed in advance before the image formation. However, the determination may be performed in real time during the image formation. In that case, a non-ejection flag is prepared for each ejection port and set in advance. Then, the recording of the forward path is started, and if the first ejection is performed for each ejection port, the non-ejection flag is reset. However, preliminary discharge is excluded. At the same time, the moving distance of the recording head from the preliminary ejection is measured by the CPU. For example, the distance is measured by counting the number of pulses applied to the drive motor in the carriage drive control circuit 304, or by arranging a sensor at a position corresponding to the discharge allowable interval with the preliminary discharge position as a base point. It may be configured to detect that the position has been reached. If the carriage movement distance has passed the allowable discharge interval, the non-ejection flag is tested for subsequent printing operations, and ejection is not performed in the forward path for ejection ports for which the corresponding non-ejection flag is set. Then, on the return path, the recording operation is performed in the manner of steps S806 and S807 in FIG.

  In this way, it is not necessary to perform the determination in step S802 for image data in advance, and image formation can be started quickly. In addition, it is easy to determine whether or not each discharge port satisfies the condition of step S802. In this way, by changing the recording operation based on the real time, it is possible to output a higher quality image.

[Third Embodiment]
In the third embodiment of the present invention, a case where a recording medium having a width of 12 inches larger than 8 inches is recorded will be described. The configuration of the recording apparatus is the same as in the first embodiment and the second implementation system. In the third embodiment of the present invention, a recording head in which the ink discharge port arrays shown in FIG. However, the recording apparatus of this embodiment can perform high-quality image formation even when the width of the recording medium is 12 inches (about 30 centimeters) exceeding the allowable discharge interval.

  FIG. 4 is a diagram showing the relationship between the discharge time and the time from the previous discharge to the discharge in the present embodiment. In the ejection state, “×” indicates a state in which the ink droplet landing position is disturbed due to the effect of ink thickening or a color change occurs due to an increase in ink density, and “△” indicates that the ink droplet landing position is not disturbed. A state in which the color changes slightly due to an increase in the ink density, and “◯” indicates a state in which the landing position of the ink droplet does not change and the color does not change due to the increase in the ink density. As shown in FIG. 4, when the time from the previous discharge to the discharge is 0.6 (seconds) or more, “X”, 0.5 (seconds) “△”, 0.4 (seconds) or less, “○ " This is the same as in the first embodiment.

  FIG. 5 is a diagram showing the positional relationship that the carriage scans in the present embodiment. The carriage rising time required for the carriage to scan the distance L1 of 1 inch from the position of the home position 501 to the end of the recording medium 503 is 0.15 (seconds). The time required for the carriage to scan the distance L2 having a width of 12 inches in the main scanning direction of the recording medium 503 is 12 (inch) / 20 (from recording at a speed of 20 inches / second). Inch / second) = 0.6 (second). The carriage fall time required for the carriage to scan a distance L3 of 1 inch from the end on the preliminary ejection position side of the recording medium 503 to the preliminary ejection position 502 is 0.15 (seconds).

  From the relationship between the time from the previous discharge to the discharge in FIG. 4 and the discharge state, if the time from the previous discharge to the discharge is not within an allowable discharge interval, for example, 0.4 (seconds), image deterioration is caused. Even at the home position 501, preliminary ejection is performed and recording is started in the main scanning direction, but 0.15 (seconds) +0.6 (seconds) = 0.75 (seconds) to finish scanning the recording medium 503. This is necessary, and causes an ejection failure at an ink ejection port having image data only in the latter half of the main scanning direction of the recording medium.

  In the present embodiment, the time required to record the vicinity of the central portion of the recording medium having an L2 = 12 (inch) width in FIG. 5 is 0.15 (seconds) +0.6 (seconds) / 2 = 0. 45 (seconds). For this reason, even when printing is performed by the printing apparatus according to the first embodiment or the second embodiment, the allowable discharge interval 0.4 (second) that does not cause a reduction in image quality is subtracted from 0.45 (second). With respect to the image data of 0.05 (seconds) near the center of the recording medium, there is a possibility that the image quality may be deteriorated in both the forward and backward recording scans. Therefore, a configuration capable of recording such an area will be described.

  FIG. 6 is a diagram for explaining a recording operation in the present embodiment. FIG. 9 is a flowchart for explaining the recording operation in the present embodiment. First, a carriage on which a recording head (not shown in FIG. 6) is mounted starts at least one image area A from the position of the home position (601). A recording operation for recording in a pass will be described.

  In step S901 in FIG. 9, first, preliminary discharge is performed from all of the 256 discharge ports of each color at the home position. Next, in step S902, printing of the image area A is started in the forward direction using all the ejection ports used for printing. Next, in step S903, after the preliminary ejection in step S901 or the ink ejection by recording the image data in the image area A is performed on each ejection port used for recording, the elapsed time remains without ink ejection. It is determined whether there is image data (that is, a dot) corresponding to a position exceeding the discharge allowable interval, for example, 0.4 seconds. For this determination, for example, the discharge state determination method based on the real time described in the modification of the first embodiment is used. However, in this embodiment, not only the ejection port but also the position of image data (for example, the position in raster order) where the ink droplets in the image area corresponding to the ejection port are to be ejected is stored in the RAM. Therefore, if the elapsed time from the last ink discharge exceeds the discharge allowable interval, the non-discharge flag is tested (read out) for the subsequent printing operation, and the discharge port for which the corresponding non-discharge flag is set As for, no discharge is performed in the outward path. In addition, the position of image data to be ejected is also stored for each ejection port.

  If “No” in the determination in step S903, that is, if there is no corresponding image data, since the recording of the image area A is completed, the image area B of FIG. 6 which is the next image area is recorded. In S915, the recording medium is conveyed by an amount of 256 dots / 600 dpi.

  On the other hand, if “Yes” in the determination in step S903, that is, if the corresponding image data is in at least one ejection port, the image data corresponding to the condition is not recorded, and the image data is recorded without satisfying the condition. Do. When the first recording scan is completed, the carriage is returned to the home position again.

  Next, in step S905, preliminary discharge is performed from all discharge ports at the home position. After the preliminary ejection, in step S906, the carriage is moved to a position where image data corresponding to the condition in step S903 that was not recorded in step S904 is to be recorded. This destination position is the position closest to the home position among the positions for each discharge port stored as the position of the first image data after the elapsed time exceeds the allowable discharge interval without ink being discharged. The moving speed at that time is a speed of 40 inches / second, which is faster than the speed of 20 inches / second, which is the carriage speed during recording. Then, recording is started at a carriage speed of 20 inches / second by using the corresponding discharge port for image data that does not have been recorded in step S904 and that satisfies the condition in step S903.

  Next, in step S907, the non-elapsed elapsed time from the last ink ejection is ejected for each ejection port that is not recorded in step S904 and meets the conditions in step S903 (that is, the ejection port used in the step S907). It is determined whether there is image data corresponding to a position exceeding an allowable interval, for example, 0.4 seconds. If “No” in the determination in step S907, the recording of the image area A is completed. Therefore, in order to record the next image area, image area B in FIG. 6, in step S915, the recording medium is conveyed by an amount of 256 dots / 600 dpi.

  If “Yes” in the determination in step S907, recording is not performed for image data that satisfies the condition in step S907, and recording is performed for image data that does not satisfy the condition. When the recording scan is completed, the carriage is moved to the preliminary ejection position 602 which is not the home position. Then, the same control as step S901 to step S906 is performed for the return direction. That is, preliminary ejection is performed from all ejection ports at the preliminary ejection position in step S909. After the preliminary ejection, in step S910, recording of image data that meets the condition of step S907 that was not recorded in step S906 is started in the backward direction.

  Next, in step S911, the time since the last ink ejection is ejected to each ejection port used to record image data that meets the conditions in step S907 not recorded in step S906. It is determined whether there is image data exceeding an allowable interval, for example, 0.4 seconds. In the case of “No” in the determination in step S911, after the recording of the image area A is completed in this way, the recording medium is set to 256 dots / second in step S915 in order to record the image area B of FIG. Carries 600 dpi.

  If “Yes” in the determination in step S911, in step S912, recording is not performed for the image data that satisfies the condition in step S911, and recording is performed for the image data that does not satisfy the condition, and the recording scan is completed. Return the carriage to the preliminary ejection position again.

  Next, in step S913, preliminary ejection is performed from all ejection ports at the preliminary ejection position. After the preliminary ejection, in step S914, 40 inches / second, which is faster than the carriage speed of 20 inches / second, which is the carriage speed at the time of recording, to the position corresponding to the image data that meets the conditions in step S911, not recorded in step S912. The carriage is moved in the backward direction at a speed of seconds. Then, from that position, recording of image data that satisfies the condition of step S911 is started at a carriage speed of 20 inches / second. When the recording is finished, the carriage is moved to the home position. Thus, the recording of the image area A is completed. Thereafter, in order to record the image area B of FIG. 6 as the next image area, the recording medium is transported in an amount of 256 dots / 600 dpi in step S915, and in step S916, the preliminary ejection from all the ejection ports is performed at the preliminary ejection position. Perform discharge. Similar to the image area A, the image areas B and C in FIG. 6 and subsequent image areas are repeated to complete the image by repeating steps S901 to S915.

  In this way, for the ejection port whose time from when the preliminary ejection as the previous ejection is performed to when the image data is recorded is longer than the time causing the image deterioration, without performing the recording in the main scanning, The image data is recorded again after moving to an image data position that has not been recorded in the same direction as the previous main scanning direction at a speed faster than the carriage speed at the time of recording. By doing so, it is possible to reach the position of the image data to be recorded in a time shorter than the time causing the image degradation. For example, (12 (inch) / 2) / 40 (inch / second) = 0.15 (second) by moving the carriage at a speed of 40 inches / second with respect to image data near the center of the recording medium. ) That is, the carriage can be moved from the end to the center of the recording medium in 0.15 seconds. For this reason, the carriage rising time required for the carriage to scan a distance L1 of 1 inch from the position of the home position 501 to the end of the recording medium 503 is faster than the carriage speed of 20 inches / second during recording. Therefore, the value is shorter than 0.15 (seconds). However, even if the time is kept at 0.15 seconds and the moving time is simply added, 0.15 (seconds) +0.15 (seconds) = 0.3 (seconds), which causes image degradation of 0.4 (seconds). It is possible to reach the image data position in a shorter time. The remaining 0.1 seconds can be used for image formation. That is, it is possible to expand the recordable area within a given allowable discharge time.

  In this embodiment, the case of minimum one-pass printing has been described. However, the present invention is not limited to one-pass printing. In multi-pass printing, the same method as in this embodiment regarding image data scheduled to be printed in the main scan. By using, image deterioration can be prevented.

  Further, in this embodiment, when recording the forward direction, the detection of the presence or absence of ejection for forming an image is based on one-way recording for each ejection port. However, the present invention is limited to this. If the image area can be completed in the recording in the forward direction, detection of the presence or absence of ejection for forming an image is also performed for each ejection port when recording in the backward direction is started. The recording speed may be improved by reciprocal recording.

  Further, in the present embodiment, the case where the control is performed based on the time from the previous discharge has been described. However, the present invention is not limited to this, and the scanning distance from the previous discharge described in the second embodiment is used. Even if the control is performed, the same effect can be obtained.

  In step S904, the position of the movement destination is the position that is stored as the first ink discharge position after the elapsed time exceeds the allowable discharge interval while ink is not discharged, but the preliminary discharge position is used as a reference. The position moved by the main scanning by the discharge allowable interval can be fixed as the movement destination. In this way, it is not necessary to store the destination, and the configuration is simplified.

  Further, in the present embodiment, whether or not the time from the previous ejection has exceeded the discharge allowable interval time is determined during the recording scan, but it is determined in advance before recording and based on the determination result at the time of recording. A configuration for performing a recording operation may be employed.

[Fourth Embodiment]
In the first to second embodiments, the non-ejection time (or distance) is measured for each ejection port, and the ejection port whose non-ejection time exceeds the allowable time (or distance) for changing the ink characteristics, The ejection ports whose non-ejection time does not exceed the permissible time are configured so that the scanning directions during image formation are opposite to each other so that the non-ejection time does not exceed the permissible time. Further, in the third embodiment, non-ejection can be achieved even when high-speed movement to the recording position is combined with the apparatus of the first or second embodiment so that half of the recording medium cannot be formed within the allowable time. The time is configured not to exceed the allowable time.

  On the other hand, in the present embodiment, the measurement of the non-ejection interval for each ejection port is not performed, and the permissible time for changing the ink characteristics (corresponding to the permissible ejection interval) is one band from the preliminary ejection of the recording head. If it is longer than the time required to complete image formation (referred to as one scanning time), all images are formed in one main scanning.

  On the other hand, when the allowable time is one scanning time or less and one half scanning time or more, the main scanning direction is the main scanning from the edge of the recording medium toward the center with the center of the recording medium as the boundary. Half of the recording medium is formed. That is, after performing preliminary ejection at one preliminary ejection position, the recording medium is scanned to one side to record half of the main scanning of the recording medium on which preliminary ejection has been performed. The other half is also recorded in the same manner after preliminary ejection at the other preliminary ejection position.

  Further, if the recording apparatus is capable of high-speed conveyance of the recording head when recording is not performed as in the third embodiment, when the recording medium is larger using high-speed conveyance or when the deterioration time of the ink is shorter. Can also respond. In the main scanning direction, the center of the recording medium is used as a boundary, and half of the recording medium is formed in the main scanning from the end of the recording medium toward the center as in the case described above. However, half of the recording medium is further recorded by two scans in the same direction. In one scan, the range from the end of the recording medium to the allowable ink time is recorded. In the other scan, a range from the position where the recording can be performed in the first scan to the center of the recording medium is recorded. At this time, the recording head is moved by high-speed conveyance to a position where recording can be performed by the first scanning. Therefore, the upper limit of the range that can be recorded by the second scan is the range that can be recorded within the time that is obtained by subtracting the time required to move the recording head by high-speed conveyance from the allowable time of ink. The other half is also recorded in the same manner after performing preliminary ejection at the other preliminary ejection position.

  For example, the width of the recording medium is 12 inches (about 30 centimeters), the carriage moving speed is 20 inches / second (about 50 centimeters / second) during recording, and 40 inches / second (about 100 centimeters / second) during high-speed movement. Let us consider a case in which the ink changes with time as shown in FIG. In this case, recording can be performed in 0.4 seconds, assuming that the time from the preliminary ejection position of the head to the recording position is 0.15 seconds, 50 × (0.4−0.15) cm = 12.5 cm It is. Accordingly, the recording head is moved at a high speed from the recording position to a position of 12.5 centimeters, and the normal recording operation is shifted from that position. By doing this, the time required for high-speed movement is 0.4 seconds / (100 (centimeter / second) / 50 (centimeter / second)) = 0.2 seconds, and the remaining 0.2 until the ink characteristics change. In seconds, 50 centimeters / second × 0.2 seconds = 10 centimeters (4 inches) can be recorded. That is, recording of 12.5 centimeters + 10 centimeters = 22.5 centimeters is possible with these two passes. By performing this similarly in the opposite direction, it is possible to record up to a recording medium having a width of 22.5 cm × 2 = 45 cm.

  With the configuration as described above, it is not necessary to measure or determine the discharge interval for each discharge port. Further, it is possible to prevent image quality deterioration due to ink thickening.

  Note that the above-described case classification (determination of whether the allowable time for changing the ink characteristics is longer than the time required to complete image formation for one band from the preliminary ejection of the recording head) is dynamically programmed. Etc., etc. By doing so, it is possible to cope with a recording apparatus in which the preliminary ejection position can be changed according to the size of the recording medium. In addition, the program can be shared.

  In addition, since it is considered that the allowable time for the change in ink characteristics and the time required to complete image formation for one band from the preliminary ejection of the recording head are often determined depending on the type of the recording apparatus, Case classification may be determined in advance depending on the model.

It is a schematic explanatory drawing of the inkjet recording device which can apply this invention. FIG. 3 is a diagram schematically illustrating a nozzle arrangement in a recording head applicable to the present invention. FIG. 3 is a configuration diagram of a recording head applicable to the present invention. It is a block diagram which shows the control structure of the inkjet recording device which can apply this invention. It is the figure which showed the relationship between the time from the last discharge in this embodiment to discharge, and a discharge state. It is the figure which showed the positional relationship which the carriage in this embodiment scans. It is a figure explaining the recording operation in this embodiment. It is a flowchart explaining the recording operation in the 1st Embodiment of this invention. It is a flowchart explaining the recording operation in the 2nd Embodiment of this invention. It is a flowchart explaining the recording operation in the 3rd Embodiment of this invention. 1 is a perspective view of an ink jet recording apparatus to which the present invention can be applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Ink cartridge 102 Recording head 103 Paper feed roller 104 Auxiliary roller 105 Paper feed roller 106 Carriage 201 Discharge port 300 Central control part (CPU)
301 ROM
302 RAM
303 Image input unit 304 Image signal processing unit 305 Bus line 306 Operation unit 307 Recovery system control unit 308 Recovery system motor 309 Blade 310 Cap 311 Pump 312 Diode sensor 313 Recording head 314 Head temperature control circuit 315 Head drive control circuit 316 Carriage drive control Circuit 317 Paper feed control circuit

Claims (15)

An inkjet recording apparatus that performs a recording scan in which ink is ejected from a plurality of ejection ports arranged in a direction different from the main scanning direction while performing a main scanning of the recording head relative to the recording medium, and recording on the recording medium.
A preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of a recording area of the recording head with respect to the recording medium by the main scanning direction;
In the recording scan in the main scanning direction of the recording head, it is determined for each ejection port of the recording head whether the ink ejection interval at which ink is ejected first and then the ink is ejected next is within a predetermined value. Determination means to perform,
In the first recording scan, recording is performed using an ejection port whose ink ejection interval is determined to be within a predetermined value by the determination unit, and preliminary ejection is performed at the preliminary ejection unit located near the end of the first recording scan. In the subsequent second recording scan, scanning is performed in the direction opposite to that of the first recording scan, and recording is performed using the ejection port determined by the determination means that the ink ejection interval is not within a predetermined value. An ink jet recording apparatus comprising: a recording control unit that performs the operation.   2. The ink jet recording apparatus according to claim 1, wherein the ink discharge interval is an interval between preliminary discharge before the start of recording scan and first ink discharge recorded on the recording medium in the recording scan.   The ink jet recording apparatus according to claim 1, wherein the ink discharge interval is a time interval or a distance interval.   4. The determination unit according to claim 1, wherein the determination unit determines whether the ink discharge intervals are all within a predetermined value for each discharge port of the recording head before the start of recording scanning. 5. 2. An ink jet recording apparatus according to 1.   4. The apparatus according to claim 1, wherein the determination unit determines whether all ink discharge intervals are within a predetermined value for each discharge port of the print head while performing print scanning. 5. The ink jet recording apparatus described.   The ink discharge interval is given according to the time until the ink characteristics in the recording head change, and the ink discharge interval for discharging ink to one preliminary discharge portion and then discharging ink to the other preliminary discharge portion The ink jet recording according to any one of claims 1 to 5, wherein the ink jet recording has a relationship that is equal to or more than half of an ink discharge interval for discharging ink to the two preliminary discharge portions. apparatus.   When the determination unit determines that the ink discharge interval is not within a predetermined time in the first and second recording scans, the recording control unit scans the recording head in the third recording scan. 6. The recording is performed using an ejection port that is determined not to be within a predetermined time in the first and second recording scans by changing a speed. Inkjet recording apparatus. An inkjet recording apparatus that performs a recording scan in which ink is ejected from a plurality of ejection ports arranged in a direction different from the main scanning direction while performing a main scanning of the recording head relative to the recording medium, and recording on the recording medium.
A preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of a recording area of the recording head with respect to the recording medium by the main scanning direction;
In the recording scan in the main scanning direction of the recording head, it is determined for each ejection port of the recording head whether the ink ejection interval at which ink is ejected first and then the ink is ejected next is within a predetermined value. Determination means to perform,
In the first recording scan, recording is performed using the ejection port in which the ink ejection interval is determined to be within a predetermined value by the determination unit, and after the first recording scan is completed, preliminary ejection is performed in the preliminary ejection unit. In the second recording scan, the recording head is moved at a speed higher than that of the first recording scan, and then the determination unit is used to determine that the ink discharge interval is not within a predetermined value. An ink jet recording apparatus comprising: a recording control unit that performs recording.   The inkjet recording apparatus according to claim 8, wherein the first recording scan and the second recording scan are scanned in the same direction.   The inkjet recording apparatus according to claim 8, wherein the first recording scan and the second recording scan are scanned in different directions.   11. The inkjet according to claim 8, wherein the ink discharge interval is an interval between preliminary discharge before the start of recording scan and first ink discharge recorded on a recording medium in the recording scan. Recording device.   In the second recording scan, after the recording head is moved at a high speed to the first recording position for recording on a recording medium, the ejection port for which the ink ejection interval is determined not to be within a predetermined value is determined by the determination means. The inkjet recording apparatus according to claim 8, wherein recording is performed using the inkjet recording apparatus.   In the second recording scan, the recording head is moved at a higher speed than the recording scan to a position where the interval from the preliminary ejection position corresponds to the predetermined value. The inkjet recording apparatus according to claim 8, wherein recording is performed using an ejection port that is determined not to be present. A recording scan is performed in which ink is discharged from a plurality of ejection ports arranged in a direction different from the main scanning direction while the recording head is relatively main-scanned with respect to the recording medium, and recording is performed on the recording medium. A recording method by an ink jet recording apparatus having a preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of a recording area for a recording medium by the recording head,
In the recording scan in the main scanning direction of the recording head, it is determined for each ejection port of the recording head whether the ink ejection interval at which ink is ejected first and then the ink is ejected next is within a predetermined value. ,
In the first recording scan, recording is performed using an ejection port in which the ink ejection interval is determined to be within a predetermined value by the determination,
After the first recording scan is completed, preliminary ejection is performed in the preliminary ejection section located in the vicinity,
In the subsequent second recording scan, scanning is performed in a direction opposite to the first main scanning direction, and recording is performed using an ejection port determined that the ink ejection interval is not within a predetermined value. Recording method. A recording scan is performed in which ink is discharged from a plurality of ejection ports arranged in a direction different from the main scanning direction while the recording head is relatively main-scanned with respect to the recording medium, and recording is performed on the recording medium. A recording method by an ink jet recording apparatus having a preliminary ejection unit capable of preliminary ejection of ink by the recording head outside both ends of a recording area for a recording medium by the recording head,
In the recording scan in the main scanning direction of the recording head, it is determined for each ejection port of the recording head whether the ink ejection interval at which ink is ejected first and then the ink is ejected next is within a predetermined value. And
In the first recording scan, recording is performed using an ejection port in which the ink ejection interval is determined to be within a predetermined value,
After the first recording scan is completed, preliminary discharge is performed in the preliminary discharge unit,
In the second recording scan, the recording head is moved at a higher speed than the first recording scan, and then recording is performed using the ejection port determined that the ink ejection interval is not within a predetermined value. A characteristic recording method.

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