JP4144494B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus that can improve the conveyance accuracy of a recording medium without the need to improve mechanical accuracy.

  In an ink jet recording apparatus that records a desired image by ejecting ink droplets onto a recording medium, the recording head that ejects ink droplets is moved in the main scanning direction on the recording medium, and the recording medium is The operation of moving in the sub-scanning direction orthogonal to the scanning direction is repeated.

  Conventionally, the movement of the recording medium in the sub-scanning direction is generally performed by an intermittent feeding operation by a stepping motor or using a DC motor equipped with a rotary encoder. In the former case, every time the recording head records one line along the main scanning direction, a predetermined number of pulses is added to the stepping motor, and the number of steps at that time is used as the feed distance to place the recording medium in the sub-scanning direction. A fixed amount is moved (Patent Document 1). In the latter case, the amount of movement when the recording medium is fed and moved in the sub-scanning direction is read as the number of pulses of the rotary encoder, and the number of pulses for obtaining a predetermined feed amount is counted and controlled (patent). Reference 2).

Further, there is a type in which a rotary encoder is arranged on the rotation shaft of a feed roller for moving the recording medium in the sub-scanning direction, and the feed amount is controlled by counting the number of pulses (Patent Document 3).
Japanese Patent Laid-Open No. 11-334160 JP 59-171664 A Japanese Patent Laid-Open No. 4-19149

  In recent years, in order to record high-quality images at high speed, the number of nozzles of the recording head increases, and the length along the nozzle row of the recording head (the length in the sub-scanning direction) becomes longer. Along with this, the feed amount has become longer, and accordingly, it has become essential to improve the feed accuracy. For example, conventionally, as a method for recording an image, a method for obtaining a high-quality image free from banding by printing the image for each block has been studied. In such a recording method, the recording medium is moved in the sub-scanning direction. It is necessary to move at a large feed distance at a time, and because the feed accuracy is drastically improved, it is actually not printed in this way. .

  In an ink jet recording apparatus, as described above, the recording medium feed amount is indirectly grasped by counting the number of pulses of the stepping motor that rotates the recording medium feed roller and the number of pulses of the rotary encoder. For this reason, an error occurs with the actual recording medium feed amount, and the image quality is deteriorated due to the occurrence of white stripes between the blocks due to this error.

  That is, the feed amount of the recording medium ascertained by counting the number of pulses, whether it is a stepping motor or a DC servo motor using a rotary encoder, is an error in the diameter of the feed roller, the axial position of the feed roller, Due to many factors such as the difference in thickness of the recording medium and slippage between the feeding roller and the recording medium, it does not represent the true feeding amount of the recording medium, and this is an error between the actual feeding amount of the recording medium. This causes white streaks and the like. Such a problem tends to be improved when a rotary encoder is mounted on the rotation shaft of the feed roller, but a sufficient improvement effect is not obtained with respect to an increase in the feed amount.

  In order to improve the conveyance accuracy, a method of improving the mechanical accuracy is also conceivable, but in order to improve the mechanical accuracy, an increase in the size of the apparatus and an increase in cost are inevitable. In particular, in a large-sized printer that performs printing, the increase in cost becomes significant.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus capable of improving the recording medium conveyance accuracy without the need to improve the mechanical accuracy.

  Other problems of the present invention will become apparent from the following description.

The above problems are solved by the following inventions.
(Claim 1) A recording head for ejecting ink droplets toward the recording medium, a recording head moving means for moving the recording head along the main scanning direction, and the recording medium on the conveying belt along the sub-scanning direction Recording medium conveying means for conveying the recording medium, conveying control means for controlling the conveying amount for conveying the recording medium by transmitting an electric pulse to the recording medium conveying means, and a desired conveying amount by the recording medium conveying means. And a detection unit that detects that the sheet has been transported at a small constant transport amount, wherein the transport control unit transmits the signal to transport at a constant transport amount that is less than a desired transport amount. The number of electrical pulses is stored, and the actual transport amount detected by the detecting means and the stored actual number of electrical pulses from the stored number of electrical pulses are used as a result of transport as an electrical signal. Out, an ink jet recording apparatus and transmits an electrical signal in the remaining conveyance amount on a recording medium conveying means on the basis of the conveying performance.

  (2) The recording head forms marks on the conveyor belt at a predetermined interval, and the detecting means detects that the sheet has been conveyed by a certain conveyance amount by detecting the mark. The ink jet recording apparatus according to claim 1.

  (Claim 3) The recording head forms marks on the recording medium at predetermined intervals, and the detecting means detects that the recording medium has been conveyed by a constant conveyance amount by detecting the mark. The ink jet recording apparatus according to claim 1.

  (Claim 4) The ink jet recording apparatus according to claim 1, wherein the recording medium includes at least a cloth.

  According to the first aspect of the present invention, it is possible to provide an ink jet recording apparatus capable of improving the recording medium conveyance accuracy without the need to improve the mechanical accuracy.

  According to the second aspect of the present invention, it is possible to provide an ink jet recording apparatus that can improve the conveyance accuracy of the recording medium without affecting the recording medium and without having to improve the mechanical accuracy.

  According to the third aspect of the present invention, there is provided an ink jet recording apparatus capable of improving the recording medium conveyance accuracy without the need to improve the mechanical accuracy only by changing the control of the conventional apparatus configuration. Can do.

  According to the fourth aspect of the present invention, it is possible to provide an ink jet recording apparatus that can improve the conveyance accuracy of a recording medium without having to improve the mechanical accuracy even with a large recording apparatus that records on a cloth. it can.

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

  FIG. 1 is a configuration diagram showing an outline of an ink jet recording apparatus according to the present invention. In the figure, H is a recording head. Here, for example, four heads h1 to h4 corresponding to four colors of YMCK are shown, but the number of heads constituting the recording head H is not particularly limited.

  On the lower surface of each head h1 to h4, a large number of nozzles (not shown) are arranged in a line along a direction substantially orthogonal to the main scanning direction of the recording head H, and are provided in the main body of the ink jet recording apparatus. The head driver 11 that is driven and controlled by the control unit 10 controls the ejection of ink from the nozzles of the heads h1 to h4 in the downward direction in FIG. A desired image is recorded and formed on a recording medium P arranged to face the nozzle surface.

  The recording head H is mounted on a carriage (not shown). The heads h1 to h4 are integrated with each other, and the main scanning motor 13 is driven by the motor driver 12 that is driven and controlled by the control unit 10 along the main scanning direction. Can be moved in both directions. In the present embodiment, the control unit 10, the motor driver 12, and the main scanning motor 13 constitute the recording head moving means of the present invention.

  The recording medium P is sandwiched between a pair of feed rollers R1 and R2 that are rotationally driven by the sub-scanning motor 15, and is driven by a motor driver 14 that is driven and controlled by motor control pulses sent by the control unit 10. 15 is driven intermittently by a predetermined amount along the sub-scanning direction (left direction in the figure) substantially orthogonal to the scanning direction of the recording head H. The motor control pulse is appropriately counted by the control unit 10, and the count number is stored in the storage unit 17. In the present embodiment, the control unit 10, the motor driver 14, the sub-scanning motor 13, and the feed rollers R1 and R2 constitute the recording medium transport unit of the present invention.

  In the ink jet recording apparatus according to the present invention, the head driver 11 is driven and controlled by the control unit 10 in the process of moving the recording head H along the main scanning direction by the recording head moving unit. Control is performed so that a predetermined mark M is recorded on the recording medium P by ejecting ink droplets from at least one of the nozzles.

  The mark M recorded on the recording medium P can be recorded by ejecting ink droplets in the process of moving the recording head H in the main scanning direction, and can be detected by a mark detection means described later. In this case, it is recorded as a straight line (line) having a certain length (for example, 1.0 mm) along the main scanning direction. If the mark M is such a line-shaped mark, recording can be easily performed by only scanning the recording head H, and detection by a mark detection means described later can be performed accurately. Can be moved more accurately.

  In the case of the recording head H composed of a plurality of heads h1 to h4 as shown in the present embodiment, the head for recording the mark M may be any one of the heads (for example, the head h4), and the ink droplets. The nozzle which discharges should just be from any one nozzle of the one head.

  A case where the mark M is formed on the recording medium will be described as an example.

  When the mark M is recorded using a plurality of heads to record an image of a plurality of colors of ink, if the recording is performed using Y (yellow) ink, the mark M is conspicuous on the recording medium P. It is preferable because it becomes difficult. In addition, in the case where light and dark inks can be ejected from a plurality of heads, it is preferable to use light Y ink because it is less noticeable.

  Further, in order to prevent the image from being affected by the area where the mark M is recorded, as shown in FIG. 2, non-printing areas where printing is not performed on both sides along the sub-scanning direction of the recording medium P are provided. When recording the “image with borders”, it is preferable to record the mark M in a non-printing area outside the printing area of the recording medium P. In this case, the mark M may be recorded in each of the non-printing areas on both sides, but only if only one of the non-printing areas is recorded, specifically on the side where the optical sensor described later is provided. Good.

  As shown in FIG. 1, an optical sensor 16 of the detecting means of the present invention is provided at one end portion of the recording head H along the main scanning direction. The optical sensor 16 can be configured as shown in FIG. 3, for example. As the optical sensor 16, a recording medium detection sensor or the like used in a conventional ink jet apparatus can also be used. The optical sensor 16 shown in FIG. 3 has a light emitting element 163 that irradiates detection light obliquely toward the surface of the recording medium P through the opening 162 and condenses the detection light on the surface of the recording medium P. A condensing lens 164 that converges, a condensing lens 165 that condenses and converges the reflected light reflected by the surface of the recording medium P, and a light receiving element 166 that receives the detection light collected by the condensing lens 165. The mark M is detected by detecting a change in the amount of light when the detection light irradiated on the recording medium P passes through the mark M on the moving recording medium P. It is supposed to be. An output signal from the optical sensor 16 is input to the control unit 10, and the control unit 10 determines whether or not the mark M is detected. In the present embodiment, the optical sensor 16 and the control unit 10 constitute the detection means of the present invention.

  When the mark M is recorded with Y ink, a blue LED (wavelength: 460 nm to 500 nm) is used as the light emitting element 163 used in the optical sensor 16 so that the mark M can be detected satisfactorily. The light receiving element 166 is preferably a light receiving element that is sensitive to light of a wavelength emitted by blue, that is, the blue LED. As such a light receiving element 166, a photosensor is generally used.

  In the optical sensor 16 shown in FIG. 3, the optical axes L1 and L2 of the detection light emitted from the light emitting element 163 and received by the light receiving element 166 are opposed to each other with an angle θ along the sub-scanning direction. However, the present invention is not limited to this, and is arranged so as to be inclined along the main scanning direction with respect to the surface of the recording medium P (a conveyance belt in a mode in which a mark M is recorded on a conveyance belt described later). You may make it do. That is, the light emitting element 163 and the light receiving element 166 are arranged so that the optical axes L1 and L2 are opposed to each other along the main scanning direction with an angle θ. As described above, the optical axes L1 and L2 of the detection light are inclined along the main scanning direction substantially orthogonal to the conveyance direction (sub scanning direction) of the recording medium P, so that the recording medium P (or conveyance) along the sub scanning direction is obtained. The belt is less susceptible to fluctuations in the height position of the surface, and the light receiving element 166 allows detection with less error.

  The detection unit detects that the recording medium is conveyed by a recording medium conveyance unit with a certain conveyance amount (for example, 30 mm) smaller than a desired conveyance amount (for example, 40 mm). At this time, it is preferable that the position where the optical sensor 16 as the detection unit is provided is determined by the relationship with the ink ejection position in the recording head H mounted on a carriage (not shown). Specifically, the distance formed by the distance between the optical sensor 16 and the ink ejection position in the recording head H is a position where the distance conveyed by a constant conveyance amount is smaller than the distance conveyed by the desired conveyance amount. It is determined. By determining the position of the optical sensor 16 in this way, the conveyance amount by which the recording medium is conveyed after the recording head H ejects ink and records the mark M until the detection means detects the mark M. Is equal to the distance formed by the distance between the optical sensor 16 and the ink ejection position in the recording head H. Therefore, the detection means can detect that the recording medium is conveyed by a recording medium conveyance means with a certain conveyance amount smaller than a desired conveyance amount when the mark M is detected.

  FIG. 4 is a flowchart showing an example of a control operation when the recording medium is conveyed by a desired conveyance amount in the sub-scanning direction in the inkjet recording apparatus of the present invention. An example of the control operation will be described with reference to this flowchart and FIG.

  When transporting a desired transport amount z in the sub-scanning direction, the control unit 10 drives and controls the head driver 11 to record the mark M by the recording head H (S1).

  When the recording of the mark M is completed, the controller 10 controls the motor driver 14 with the motor control pulse to drive the sub-scanning motor 15 at a high speed, thereby conveying the recording medium in the sub-scanning direction (S2). At this time, the number of motor control pulses is greater than the number of pulses when the distance x from the mark recording position to the mark detection position is theoretically calculated and the error is added. A numerical value is desirable. At this time, the distance x is shorter than the distance by the desired transport amount z.

  Next, when the mark M is detected, the signal is sent to the control unit 10, and the motor control pulse number m at that time is acquired from the motor driver 14 (S3).

  Based on the number of motor control pulses acquired in S3, a transport amount per pulse (also referred to as a transport result in the present invention) is calculated (S4). The number of motor control pulses acquired in S3 is the number of pulses necessary to actually convey the distance from the mark recording position to the mark detection position. Therefore, the conveyance amount per pulse can be determined by setting x / m.

  Next, it is calculated how many pulses are to be sent so that the entire transport amount becomes the desired transport amount z (S5). Specifically, the number of pulses to be sent = m / x × (z−x−n × x / m) is calculated from the number n of pulses overrunning the mark M due to the inertia of the motor and the desired carry amount z.

  The number of pulses calculated in S5 is sent to the motor driver 14 (S6).

  After the process of S6 is completed, the process of S1 to S6 is repeated while the recording medium is conveyed and recorded by the ink jet recording apparatus of the present invention.

  As an aspect different from the above conveyance, after detecting the mark M, the number of pulses m for conveying the distance x is canceled, and when the mark M is detected, the distance is newly shorter than the distance by the desired conveyance amount z. While sending the number of pulses mm for conveying the distance xx longer than x to the motor driver 14 and the motor is moving, the distance x is the distance xx and the number of pulses m is the number of pulses mm. It is better to calculate the number of pulses until the distance z is reached and send it again as an addition.

  FIG. 5 is a flowchart showing another example of the control operation when the recording medium is transported by a desired transport amount in the sub-scanning direction in the ink jet recording apparatus of the present invention. Another control method different from the above two control methods will be described with reference to the flowchart of FIG. 5 and FIG.

  In FIG. 5, when transporting a desired transport amount z in the sub-scanning direction, the control unit 10 drives the head driver 11 to record the mark M by the recording head H (S11).

  When the recording of the mark M is completed, the control unit 10 controls the motor driver 14 with motor control pulses to drive the sub-scanning motor 15 at a high speed, thereby conveying the recording medium in the sub-scanning direction (S12). The number of motor control pulses is counted (S13).

  The operations of S12 and S13 are repeated until the mark M is detected by the optical sensor 16 (S14). When the mark M is detected in S14, the control unit 10 determines that the recording medium has been transported by a certain transport amount x smaller than the desired transport amount.

  Next, the control unit 10 calculates the transfer result by x / p based on the number of pulses p counted when the fixed transfer amount x is transferred, and calculates the number of pulses required for the remaining transfer (S15).

  By driving and controlling the motor driver 14 with the calculated number of pulses and driving the sub-scanning motor 15, the recording medium is conveyed in the sub-scanning direction (S16).

  After the process of S16 is completed, the process of S11 to S16 is repeated while the recording medium is conveyed and recorded by the ink jet recording apparatus of the present invention.

  By controlling in this way, it is possible to improve the recording medium conveyance accuracy without the need to improve the mechanical accuracy. In particular, in this aspect, variation in the conveyance amount unique to the apparatus due to component variation can be controlled by simply calculating the number of pulses, and the above-described effect can be achieved.

  In the above description, the mode in which the mark M is recorded on the recording medium P by the recording head H has been described as an example. However, the mode shown in FIG.

  In the embodiment shown in FIG. 6, a belt cleaner C for cleaning the mark M is provided, the mark M is recorded in a portion to be cleaned by the belt cleaner C, and the mark M is cleaned by the belt cleaner C. To control.

  The conditions to be satisfied by the sensor and belt in this case will be described.

  When the mark M is formed on the conveyance belt, the position where the mark M is recorded is the surface of the belt member that protrudes from both sides of the recording medium, and may be at least one of the surfaces. May be on the side where the optical sensor 16 described above is provided.

  As described above with reference to FIG. 6, the optical sensor 16 serving as a mark detection unit is disposed at a predetermined distance from the recording head H on the downstream side of the recording head H in the transport direction. The optical sensor 16 detects a change in the amount of light when the detection light applied to the surface of the belt member passes through the mark M described on the moving belt member. The presence is to be detected. The detection signal of the mark detection means is output to the control unit 10 shown in FIG.

  The use of mark detection means for detecting the presence of the mark M using light in this way is a preferable mode because the mark M can be detected at high speed without contact, but in this case, the mark M In order to perform detection easily and reliably, it is preferable that at least the belt member and the mark M, that is, the ink on which the mark M is recorded have different light reflectivities. The greater the difference in light reflectance, the easier it is for the mark detection means to detect the mark M recorded on the surface of the belt member.

  The light reflectance of the belt member and the mark M can be made different by appropriately selecting the material of the belt member and the color of the ink for recording the mark M. The surface of the belt member emits light. A surface treatment having a wavelength region in which reflection occurs with respect to the light emission wavelength of the element is preferable. As an example, when the wavelength of the light emitting element is arbitrary, the surface is reflected with respect to all wavelengths and is visually white, specifically, the surface is formed of silicon or urethane and is white. For example, “Belt type FNB-2E” manufactured by Habasit Japan Co., Ltd.) can be used. In this case, the ink for recording the mark M on the surface of the belt member may be any ink that absorbs the wavelength of the light emitting element because the belt totally reflects the light. It is also effective against As another method, the surface may be subjected to surface treatment having a wavelength region in which irregular reflection occurs with respect to the emission wavelength of the light emitting element. As an example of this, the belt surface can be one having irregularities on the surface, for example, “belt type FNT-5P” manufactured by Habasit Japan Co., Ltd. can be used. The ink for recording the mark M in this case may be any ink as long as the surface roughness is substantially smooth and reflected by the ink, and in particular, magenta or cyan ink (viscosity 4 cp, surface tension 50 dyne). . As described above, since the reflectance of light between the belt member and the mark M is different, the presence of the mark M can be easily recognized by the mark detection means.

  According to this aspect, the above effects can be obtained without affecting the recording medium.

  Also, in any of the above-described ink jet recording apparatuses, the effect can be more effectively exhibited by being used as a large recording apparatus such as a so-called textile printing apparatus using cloth as the recording medium P.

1 is a configuration diagram showing an outline of an ink jet recording apparatus according to the present invention. The figure which shows the recording position of the mark on the recording medium Diagram showing the structure of an optical sensor Flowchart showing an example of control operation during movement of recording medium Flowchart showing another example of control operation during movement of recording medium The schematic block diagram for demonstrating the other aspect of this invention

Explanation of symbols

H: Recording head h1 to h4: Head P: Recording medium M: Mark R1, R2: Feed roller 10: Control unit 11: Head driver 12: Motor driver 13: Main scanning motor 14: Motor driver 15: Sub scanning motor 16: Optical sensor 17: storage unit

Claims (4)

A recording head that ejects ink droplets toward the recording medium;
Recording head moving means for moving the recording head along the main scanning direction;
Recording medium conveying means for conveying the recording medium on the conveying belt along the sub-scanning direction;
A transport control means for controlling a transport amount for transporting the recording medium by transmitting an electric pulse to the recording medium transporting means;
An ink jet recording apparatus having detection means for detecting that the recording medium is transported by a constant transport amount smaller than a desired transport amount by the recording medium transport unit;
The transport control unit stores the number of electrical pulses transmitted for transporting at a constant transport amount smaller than a desired transport amount, and the actual transport amount detected by the detection unit and the stored number of electrical pulses. Ink jet recording apparatus, wherein a transport record that is an electrical signal with respect to an actual transport amount is calculated from the above, and an electrical signal corresponding to the remaining transport amount is transmitted to a recording medium transport unit based on the transport record.   2. The recording head according to claim 1, wherein marks are formed at predetermined intervals on the conveyance belt, and the detection unit detects that the conveyance is carried by a certain conveyance amount by detecting the mark. Inkjet recording apparatus.   2. The recording head according to claim 1, wherein the recording head forms marks on the recording medium at predetermined intervals, and the detection unit detects that the recording medium is conveyed by a certain conveyance amount by detecting the mark. Inkjet recording apparatus.   The inkjet recording apparatus according to claim 1, wherein the recording medium includes at least a cloth.

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