JP2006026990A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer that accurately adjusts the impact position of ink drops even if the resolution is high and the ink diameter is small. <P>SOLUTION: The inkjet recording device detects the positions of flying ink drops by an optical ink drop detection mechanism provided in the device and thereby adjusts the pitch, roll and yaw of the head. The head has motors (64X, 64Y and 64Z) in the X, Y and Z axes and can adjust the pitch, roll and yaw. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an ink jet recording apparatus that performs recording on a recording medium by discharging ink from a recording head, and more particularly to adjustment of the recording head.

    Inkjet recording devices have improved image quality year by year due to the high definition of nozzles and the use of multiple ink colors. In order to perform printing with high image quality, the accuracy of the landing positions of the ejected ink droplets is important. The dot landing position deviation caused by the deviation of the recording head mounting angle greatly affects the image quality in the form of deterioration of graininess or change in color. Therefore, an adjustment pattern is printed on the recording medium, and this is read visually or with a reflection sensor or the like to perform registration adjustment to correct the landing position.

JP-A-11-216854

  However, as the recording resolution on the recording medium is improved and the dot diameter is reduced by increasing the definition of the nozzle and reducing the ink droplets, it is difficult to visually determine the pattern. In addition, since the dots on the recording medium are blurred, the adjustment by the reflection sensor includes noise corresponding to the blur.

  Therefore, even if you adjust the landing position of the ink by looking at the pattern with your eyes, there is a limit as long as you can see with your eyes. Even if the ability to form an image is maintained, it cannot be adjusted sufficiently.

  As a result, the image quality cannot be raised beyond a certain level by adjustment, and the rest is due to the improvement of the component accuracy.

  Therefore, in view of the above problems, the present invention detects the position of a flying ink droplet ejected from a nozzle, and adjusts the angle of the recording head from the result, so that even if the resolution and the size of the droplet are reduced, Accurate adjustment is possible.

  In order to achieve the above object, an image forming apparatus according to claim 1 of the present invention is equipped with a print head for ejecting ink, and in the image forming apparatus for ejecting ink onto a recording medium to record an image, the head is The inkjet recording apparatus includes a plurality of nozzle rows and adjusts the yaw angle of the recording head from a detection result of an ink droplet detection mechanism provided in the apparatus.

  According to a second aspect of the present invention, there is provided an image forming apparatus having a print head for ejecting ink and recording an image by ejecting ink onto a recording medium. The inkjet recording apparatus is characterized in that the pitch angle of the recording head is adjusted from the detection result of the ink droplet detection mechanism provided in the apparatus.

  Furthermore, in the image forming apparatus according to claim 3 of the present invention, the print head for ejecting ink is mounted, and the head forms a plurality of nozzle rows in the image forming apparatus for recording an image by ejecting ink onto a recording medium. The inkjet recording apparatus is characterized in that the roll angle of the recording head is adjusted from the detection result of the ink droplet detection mechanism provided in the apparatus.

  Furthermore, in the image forming apparatus according to claim 4 of the present invention, the detection mechanism includes a pair of a light emitting portion and a light receiving portion so that the ink droplets ejected from the recording head block the measurement optical axis. 4. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is provided.

  According to the ink jet recording apparatus having such a configuration, the pitch angle, yaw angle, and roll angle of the recording head are adjusted from the detection result of the ink droplet detection mechanism that includes a plurality of nozzle rows and is provided in the apparatus. Even if the droplet is fine, accurate adjustment is possible.

  Hereinafter, a schematic configuration of a plotter as an ink jet recording apparatus in which an embodiment of the present invention is incorporated will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a schematic configuration of a plotter to which the present invention is applied. The plotter 10 includes a platen 14 on which the recording paper 12 conveyed in the direction of arrow A is placed. Two scanning rails (guide rails) 16 are spanned above the platen 14 in parallel to the platen 14. A carriage 20 that reciprocates in the directions of arrows B and C (directions orthogonal to the direction of arrow A) by a motor (not shown) and a belt 18 is attached to the scanning rail 16 via a slide bearing (not shown). Yes. On the carriage 20, four recording heads 22K (black), 22C (cyan), 22M (magenta), and 22Y (yellow) having nozzle arrays for ejecting ink are mounted. In front of the ink ejection opening is an image forming area 23 where an image is formed. Ink is ejected from the nozzles to a portion of the recording paper 12 that is located in the image forming area 23, whereby an image is formed in this portion.

  In a corner of the movable range of the carriage 20 away from the image forming area 23, ink is forcibly sucked from the nozzles, and the ink supply path and nozzles formed on the recording head 22 are cleaned and recorded. A recovery device 30 is provided that changes the ink discharge state of the head 22 to the initial discharge state. In forming an image on the recording paper 12 such as roll paper, the recording paper 12 was placed on the platen 14 and a part of the outer peripheral surface was exposed from an opening (not shown) formed in the platen 14. The recording paper 12 is conveyed by rotating the conveying roller 24 by a conveying motor (not shown) while the recording paper 12 is sandwiched between the conveying roller 24 and the pinch roller 26 that presses both ends of the recording paper 12 from above. The carriage 20 is reciprocated in the directions of arrows B and C above the recording paper 12, and based on image signals carrying image information transmitted from the control device (not shown) to the recording heads 22K, 22C, 22M, and 22Y. Then, ink is ejected from the nozzles to form an image on the portion of the recording paper 12 that is positioned in the image forming area 23. During the image forming operation, when it becomes necessary to suck ink from the nozzles in order to clean the nozzles, the carriage 20 is moved above the recovery device 30. When the image formation is completed, a cutter (not shown) mounted on the carriage 20 is ejected to a predetermined position, and the recording paper 12 is cut into a predetermined size.

  The recovery device 30 includes four rubber caps 32K, 32C, 32M, and 32Y that detachably cover the outlets of the nozzles of the four recording heads 22K, 22C, 22M, and 22Y. One end of a tube (not shown) is connected to each cap 32K, 32C, 32M, 32Y, and the other end of the tube is connected to a suction pump (not shown). The four caps 32K, 32C, 32M, and 32Y are fixed to the cap base 32.

    As shown in FIG. 2, the control device described above includes an image controller 33 for controlling print data (image data) carrying image information, an engine controller 36 for controlling the conveyance of the recording paper 12 and the movement of the carriage 20, and The recording head controller 33 is configured to control ejection signals of ink ejected from the recording heads 22K, 22C, 22M, and 22Y. The engine controller 36 is used for a data rasterization unit 37 that divides print data sent from the image controller 32, a print parameter change unit 35 that changes print parameters according to the type of recording paper and output quality, and ink ejection. It includes a discharge pulse generator that generates pulses, a transport control unit 41 that controls a transport motor 46 that rotates the transport roller 24, and the like.

  The photosensor provided as a means for detecting the ejection state of the ink droplet is a transmission that optically detects the ink droplet 59 ejected from the nozzle toward the preliminary ejection receptacle 57 installed outside the printing area as shown in FIG. Type photo interrupter. The photosensor used here uses an infrared LED as the light emitting element 54, and a lens is integrally formed on the LED light emitting surface so that beam light can be projected toward the light receiving element 55. The optical axis of the beam is parallel to the correct position of the nozzle row.

  A phototransistor is used as the light receiving element 55, and the interval between the light emitting element 54 and the light receiving element 55 is wider than the nozzle row. By passing the ink droplets during this period, the ink droplets block the light from the light emitting side, reduce the amount of light to the light receiving side, and change the output of the phototransistor of the light receiving element 55.

  The light beam may be narrowed by installing a mold member 56 in which a hole of about 0.7 mm × 0.7 mm, for example, is formed on the front surface of the light receiving surface of the light receiving element 55. By narrowing the detection region in the light beam of the beam light by this pinhole, the phototransistor output difference (S / N ratio) between when the ink droplet is present and when it is not present can be increased. The means for narrowing the detection area is not limited to the pinhole, and a slit or the like may be used. When the ink droplet blocks the beam light, the output of the light receiving element 55 changes as shown in FIG. This change is taken out as an output signal 61. When the output is taken out as the digital signal 63, the threshold 62 is provided to perform A / D conversion.

FIG. 6 shows an example of a configuration capable of adjusting the three-axis position of the nozzle row. An adjustment motor is provided for each of the X, Y, and Z axes, and the pitch angle is adjusted by the motor 64X, the roll angle is adjusted by the motor 64Y, and the yaw angle is adjusted by the motor 64Z.
As the adjustment motor, a small ultrasonic motor capable of high-precision control is desirable. Further, if a ball-joint spherical ultrasonic motor is used, the configuration can be simplified as shown in FIG.

  If the yaw angle (angle around the Z-axis) of the nozzle row is shifted as shown in Fig. 8, if ink droplets are ejected from the front, center, and rear end nozzles, as shown in Fig. 9, Since the area where the ink droplets flying through the light block the light increases, the peak of the output signal 65 increases. On the other hand, when there is no deviation in the yaw angle as shown in FIG. 11, the peak area of the output signal 65 is also minimized because the area to be blocked is minimized as shown in FIG. Therefore, it is possible to set the correct yaw angle by adjusting so that the peak of the output signal 65 is minimized.

  As the number of nozzles provided in the recording head increases, the distance between the light-emitting element 53 and the light-receiving element 54 increases, and a beam with high directivity is required. Therefore, by using a laser light source or the like instead of the infrared LED, Stable measurement can be performed.

  Next, the pitch angle adjusting means of the recording head using the ink droplet detection mechanism described in the embodiment will be described. If the recording head pitch angle (angle around the X axis) is misaligned, the trajectory of the measurement optical axis 58 and the ink droplet 59 flying does not intersect at right angles as shown in FIG. Compared to the case where there is no ink droplet, the distance that the ink droplet travels in the optical axis becomes longer (d <d ′). This difference in distance can be expressed as a difference in time during which an ink droplet is detected. Therefore, the threshold value 62 is provided for the output signal 61 from the light receiving element 54 to perform A / D conversion, and the pitch angle of the recording head is adjusted so that the time t during which the ink droplet is detected is minimized. This makes it possible to set the correct pitch angle.

  Furthermore, the roll angle adjusting means of the recording head using the ink droplet detection mechanism described in the embodiment will be described. The nozzle row is positioned directly above the measurement optical axis 58, and ink droplets are ejected. When the roll angle (angle around the Y axis) is deviated, the trajectory of the ink droplet 59 does not pass through the center of the measurement optical axis 58 as shown in FIG. Thus, the distance traveled along the optical axis is shortened (d> d ′). This difference in distance can be expressed as a difference in time during which an ink droplet is detected. Therefore, the correct roll angle can be set by adjusting the roll angle so that t is the longest.

Schematic configuration diagram of inkjet plotter 1 is a block diagram showing a part of the configuration of the plotter in FIG. Diagram showing the positional relationship between the printable area and the photo sensor A perspective view showing a configuration of a photosensor Diagram showing the output of the light receiving element when the ink droplet passes and the signal after A / D conversion An example of a configuration that can adjust the position of the three axes of the nozzle array Configuration example using spherical ultrasonic motor Nozzle row with yaw angle misalignment The figure which shows the ink drop in the optical axis for measurement when the yaw angle has shifted Photosensor output when the yaw angle is off Nozzle row when yaw angle is correct Diagram showing ink droplets in the measurement optical axis when the yaw angle is correct Photosensor output when the yaw angle is correct The figure which shows the difference in the locus of the ink drop by the deviation of the pitch angle The figure which shows the difference of the locus of the ink drop due to the deviation of the roll angle

Explanation of symbols

12 Recording medium 14 Platen 16 Scanning rail 18 Belt 22 Recording head 23 Image forming area 24 Conveying roller 26 Pinch roller 30 Recovery device A Paper conveying direction
B Carriage scanning direction (outward)
C Carriage scanning direction (reverse)
31 Host computer 32 Image controller 33 Print head controller 34 Discharge state detection mechanism 35 Conveyance motor 36 Engine controller 37 Data rasterization unit 38 Print parameter change unit 39 Discharge pulse generator 40 Correction circuit 41 Conveyance control unit 51 Printable area 52 Linear scale 53 Scale Reading sensor 54 Light emitting element 55 Light receiving element 56 Mold member 57 Preliminary discharge receiver 58 Optical axis for measurement 59 Ink droplet 61 Light receiving element output 62 Threshold 63 Signal 64 after A / D conversion Motor for adjustment

Claims (4)

In an image forming apparatus equipped with a print head for ejecting ink and recording an image by ejecting ink onto a recording medium,
An ink jet recording apparatus, wherein the head includes a plurality of nozzle rows, and the yaw angle of the recording head is adjusted from a detection result of an ink droplet detection mechanism provided in the apparatus. In an image forming apparatus equipped with a print head for ejecting ink and recording an image by ejecting ink onto a recording medium,
An ink jet recording apparatus, wherein the head includes a plurality of nozzle rows, and the pitch angle of the recording head is adjusted from a detection result of an ink droplet detection mechanism provided in the apparatus. In an image forming apparatus equipped with a print head for ejecting ink and recording an image by ejecting ink onto a recording medium,
An ink jet recording apparatus, wherein the head includes a plurality of nozzle rows, and a roll angle of the recording head is adjusted from a detection result of an ink droplet detection mechanism provided in the apparatus. 4. The detection mechanism according to claim 1, wherein the detection mechanism includes a pair of a light emitting unit and a light receiving unit, and is provided so that an ink droplet ejected from a recording head blocks a measurement optical axis. Inkjet recording device.

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