JP2008207355A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer which can correct an ink strike position to displacement of a carriage in any direction. <P>SOLUTION: The inkjet printer has a three-dimensional acceleration sensor which detects accelerations of three directions of a main scan direction, a subscan direction and an inkjet head height direction from a printing medium on the carriage. An ejection timing of ink from the inkjet head is corrected by acceleration information of the main scan direction and the printing medium height direction detected by the three-dimensional acceleration sensor. A printing position in the subscan direction is corrected by shifting printing data of the printing head in the subscan direction by the acceleration information of the subscan direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing apparatus such as a printer, and more particularly to an ink jet printer in which an ink jet head is mounted on a carriage and printing is performed on a print medium by the reciprocating scanning of the carriage.

  A configuration of an ink jet printer that performs printing while reciprocating a carriage mounted with a print head will be described with reference to FIG. One or a plurality of print heads 12 are installed on the carriage 5 which is set to be movable in the horizontal direction on the support 9 so as to face the print medium 10. The rotation of the motor 7 is transmitted to the carriage drive belt 11 through the motor pulley 1, the transmission belt 2, the two-stage pulley 8, and the driven pulley 6 to drive the carriage fixed to the carriage drive belt in the horizontal direction. By reading the scale 3 installed on the support with the encoder 4 installed on the carriage, a pulse signal is generated from the encoder in accordance with the movement of the carriage, and the pulse signal is counted in the horizontal direction of the carriage. Can be specified. In FIG. 1, the ink supply unit and the control unit are omitted.

  Printing on the print medium is performed by ejecting ink from the inkjet head while moving the carriage in the horizontal direction at a constant speed. The carriage is moved at a constant speed by feeding back the carriage position information obtained from the encoder signal to the controller of the motor. However, in practice, the carriage speed varies depending on the smoothness of the support, the eccentricity of the two-stage pulley and the driven pulley, disturbance, and the like.

Patent Document 1 discloses means for detecting the carriage speed and acceleration based on a signal from the encoder and dynamically correcting the ink ejection timing of the inkjet head in response to such a carriage speed variation. An inkjet printer is disclosed.
JP2002-2046

  Since the prior art uses pulses from an encoder that reads the scale on the support, the measurement time interval and measurement accuracy of the carriage speed and acceleration are affected by the band interval and the carriage speed on the scale.

  Although the speed and acceleration in the main scanning direction at which the carriage moves can be detected, the speed due to the vibration of the carriage in the paper feed direction, that is, the sub-scanning direction, the direction perpendicular to the print medium, that is, the head height direction from the print medium, etc. Acceleration could not be detected, and correction could not be made for deterioration in print quality due to displacement of the ink landing position on the print medium due to displacement from the target position in the sub-scanning direction and head height direction. .

  Accordingly, an object of the present invention is to provide an ink jet printer capable of correcting the ink landing position with respect to the displacement of the carriage in all directions.

  In the present invention, an ink jet printer having a print head for ejecting ink and a carriage that carries the reciprocating scan operation by mounting the print head, the main scanning direction, the sub-scanning direction, and the print medium on the carriage. A three-dimensional acceleration sensor that detects acceleration in three directions in the height direction, and based on acceleration information in the main scanning direction and print medium height direction detected by the three-dimensional acceleration sensor, The ink ejection timing is corrected.

  Further, in the present invention, in the ink jet printer, the print data of the print head is shifted in the sub-scanning direction according to the acceleration information in the sub-scanning direction and the print medium height direction detected by the three-dimensional acceleration sensor. The print position in the direction is corrected.

  Further, the present invention is characterized in that a plurality of the three-dimensional acceleration sensors are provided on the carriage.

  According to the present invention, even if the position and posture of the carriage and the ink jet head mounted on the carriage and the ink jet head are changed due to the vibration of the carriage or the impact from the outside of the printer during printing by the ink jet printer, the ink is transferred to the target position on the print medium. It is possible to correct the ink discharge operation of the ink jet head so as to land. Thereby, stable print quality can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS. The structure of the carriage of the ink jet printer according to the present invention in FIG. 2 is shown for the case where three three-dimensional acceleration sensors are used. FIG. 3 is a block diagram for processing acceleration information from the three-dimensional acceleration sensor according to the present invention.

  In FIG. 2, illustration and description of an ink supply system, a paper transport system, a memory associated with a CPU, an external interface with a host, and the like, which are not directly related to the features of the embodiment of the present invention, are omitted.

  In the ink jet printer of FIG. 2, three three-dimensional acceleration sensors, a three-dimensional acceleration sensor A13, a three-dimensional acceleration sensor B14, and a three-dimensional acceleration sensor C15 are provided on the surface on which the head on the carriage of the conventional ink jet printer is mounted. It is installed so that it does not line up in the same straight line. Further, the three directions in which each three-dimensional acceleration sensor can detect the acceleration are the main scanning direction in which the carriage reciprocates, the paper feeding direction, the sub-scanning direction parallel to the arrangement of the nozzles of the inkjet head, and the inkjet head perpendicular to the print medium It is installed to fit the height direction. The acceleration in the main scanning direction is acceleration aya, acceleration ayb, and acceleration ayc, the acceleration in the sub scanning direction is acceleration axa, acceleration axb, and acceleration axc, respectively, and the acceleration in the head height direction is acceleration aza, acceleration azb, respectively. The acceleration is azc.

  A head control method based on acceleration information from the three-dimensional acceleration sensor installed on the carriage in FIG. 2 will be described with reference to the block diagram of FIG. Note that it is assumed that the three-dimensional coordinates and the initial speed of the location that is the starting point of the movement of the carriage at the end of the movement range of the carriage in the main scanning direction are determined before the carriage moves. The acceleration information in each direction from each three-dimensional acceleration sensor 16 installed on the carriage is time-integrated by the acceleration-speed conversion integration unit 17 and converted into speed information. The speed information is time-integrated by the speed-position converting integrator 18 and converted into position information. At this time, the positions of the three three-dimensional acceleration sensors on the carriage in the three-dimensional space are determined. Assuming that the carriage has sufficient rigidity, the carriage attitude calculation unit 19 uses the position information of the three three-dimensional sensors to determine the carriage position such as the position and inclination of the carriage, particularly the surface on which the inkjet head is mounted. Attitude information is calculated. Further, the head nozzle position detection unit 20 calculates the position and inclination of each inkjet head on the carriage, the position of each nozzle and the direction in which the nozzle faces, that is, the ink ejection direction, from the posture information of the carriage. At this point, the ideal position of the nozzle of each inkjet head at the current carriage position and the amount of deviation from the ejection direction are determined.

  The ink ejection timing correction unit 21 corrects the ink ejection timing at the head from the nozzle position deviation amount and the nozzle tilt angle in the main scanning direction and the head height direction. If the position of the nozzle in the main scanning direction is before the target position, the ink discharge timing is delayed, and if the position is past the target position, the ink discharge timing is advanced. Further, if the head height direction position is lower than the target position, the ink discharge timing is delayed, and if it is lower than the target position, the ink discharge timing is advanced. Further, the ejection timing is corrected according to the inclination of the ejection direction of the nozzle.

The in-head data shift amount correction unit 22 corrects the data shift amount in the head from the nozzle position shift amount and the nozzle tilt angle in the sub-scanning direction and the head height direction. Each head on the carriage is provided with a nozzle row parallel to the sub-scanning direction, and the print position in the sub-scanning direction is adjusted by shifting print data within the nozzle row. If the position of the nozzle in the sub-scanning direction is shifted to the upstream side of the print medium conveyance, the print data is shifted to the downstream side of the nozzle row in the head,
If it is shifted to the downstream side, the print data is shifted to the upstream side of the nozzle row in the head. Further, the shift amount is corrected according to the head height deviation amount and the nozzle inclination.

  By correcting the ink ejection timing and the data shift amount in the head, it is possible to bring the ink landing position on the print medium closer to the target position, and the print quality is improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various improvement and change are possible in the range which does not deviate from the meaning.

It is a block diagram of an inkjet printer. It is a block diagram which shows embodiment of this invention. It is a block diagram which shows the control method by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor pulley 2 Transmission belt 3 Scale 4 Encoder 5 Carriage 6 Driven pulley 7 Motor 8 Two-stage pulley 9 Support body 10 Print medium 11 Carriage drive belt 12 Inkjet head 13 Three-dimensional accelerometer A
14 Three-dimensional accelerometer B
15 Three-dimensional accelerometer C
16 Three-dimensional accelerometer 17 Acceleration-speed conversion integration unit 18 Speed-position conversion integration unit 19 Carriage posture calculation unit 20 Head nozzle position detection unit 21 Ink ejection timing correction unit 22 In-head data shift amount correction unit

Claims (3)

An ink jet printer having a print head that ejects ink, and a carriage that carries the print head and performs a reciprocating scanning operation,
An acceleration sensor that detects acceleration in the main scanning direction, sub-scanning direction, and print medium height direction is provided on the carriage, and the main scanning direction and print medium height direction detected by the three-dimensional acceleration sensor are included. An ink jet printer that corrects ink ejection timing from the print head based on acceleration information. The print position in the sub-scanning direction is corrected by shifting the print data of the print head in the sub-scanning direction based on the acceleration information in the sub-scanning direction and the print medium height direction detected by the three-dimensional acceleration sensor. The inkjet printer according to claim 1. The inkjet printer according to claim 1, wherein a plurality of the three-dimensional acceleration sensors are provided on the carriage.

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