JP2006289876A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer of reduced size while aiming at the coexistence of a printing quality and printing rate even at a low cost. <P>SOLUTION: When the inkjet printer is powered up, or just after a predetermined number of sheets are continuously printed, a distance X as a correction value for the stop position of a carrier 8 is computed from the output of an encoder by a motor controlling circuit. In controlling the stopping of the carrier 8 at the time of printing and performing the maintenance of a recording head, the variation of the stopping position of the carrier 8 is inhibited by correcting the position in which a brake voltage starts to be applied to a carrier driving motor according to the distance X. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet printer that forms an image by driving a carrier that supports an ink cartridge in a main scanning direction by a DC motor and ejects ink from a recording head.

  In an ink jet printer, an ink cartridge is transported by a carrier that can reciprocate in the main scanning direction, and an image is recorded on the recording paper by controlling a recording head provided in the ink cartridge in conjunction with the reciprocation. It is formed. For this reason, when the variation of the carrier stop position becomes large, the relationship between the position of the recording head and the ejection timing may be shifted, and the print quality may deteriorate.

  By the way, a DC motor is mainly used for driving a carrier of a recent ink jet printer mainly because of a request for cost reduction. Such a DC motor is inexpensive, but the position of the carrier cannot be controlled alone like a step motor. Therefore, when a DC motor is used for driving the carrier, an encoder for detecting the position of the carrier is used in combination.

  The carrier stop position generally correlates with the weight of the ink cartridge and fluctuates under the influence of the remaining amount of ink. Further, in the configuration using the DC motor described above for driving the carrier, it varies depending on the temperature of the motor.

Patent Document 1 discloses a printer configured to store a carrier stop position detected by an encoder each time one line is printed and to correct an error with respect to a target stop position.
Japanese Patent Laid-Open No. 9-58081

  However, the printer disclosed in Patent Document 1 involves a process of correcting the stop position error every time one line is printed, which causes a problem that the printing speed is reduced.

  The present invention has been made to solve the above-described problems, and provides an inkjet printer that can achieve downsizing while at the same time achieving both print quality and print speed while being low in cost. Objective.

  In order to achieve the above object, an invention according to claim 1 includes an ink cartridge having an ink tank for storing ink, a recording head for discharging an ink stored in the ink tank to form an image on recording paper, and the ink. A carrier for supporting the cartridge and transporting in a direction substantially perpendicular to the transport direction of the recording paper, a DC motor for driving the carrier, drive transmission means for transmitting the driving force of the DC motor to the carrier, and DC An encoder for detecting the position of the carrier driven by the motor and the drive transmission means, a motor control means for controlling the DC motor based on a signal output from the encoder, and when the carrier is positioned at the home position. A recording head maintenance unit that is disposed to face the recording head and performs maintenance of the recording head. The motor control means calculates the position and speed of the carrier based on the signal output from the encoder, and immediately after printing the predetermined number of sheets when the ink jet printer is turned on. Apply a predetermined brake voltage until the carrier decelerates to the second speed so that the carrier moves at the first speed by applying a predetermined drive voltage to the DC motor and then stops at the target stop position. After that, the carrier is stopped by the resistance of the drive transmission means and the DC motor, the actual stop position is detected by the encoder, the difference between the actual stop position and the target stop position is calculated and stored, and the print is executed. Stored actual stop position and target for carrier stop control during maintenance and recording head maintenance By correcting the carrier position, which is the starting point for applying the brake voltage to the DC motor, based on the difference from the stop position, fluctuations in the remaining position of the ink and fluctuations in the carrier stop position due to fluctuations in the DC motor temperature are reduced. Thus, the accuracy of the carrier stop position is improved, and it is possible to improve the printing quality and to reduce the size of the recording head maintenance means.

  According to a second aspect of the present invention, there is provided an ink cartridge having an ink tank for storing ink, a recording head for discharging the ink stored in the ink tank to form an image on recording paper, and supporting the ink cartridge and recording. A carrier transported in a direction substantially perpendicular to the paper transport direction, a DC motor for driving the carrier, an encoder for detecting the position of the carrier driven by the DC motor, and a signal output from the encoder Printer having motor control means for controlling a DC motor based on the recording head and recording head maintenance means arranged to face the recording head and maintaining the recording head when the carrier is positioned at the home position In the motor control means, the signal output from the encoder Based on this, the position and speed of the carrier are calculated, and when the ink jet printer is turned on, the carrier is moved at a predetermined speed by applying a predetermined driving voltage to the DC motor, and then stopped at the target stop position. A predetermined brake voltage is applied to stop the carrier, the actual stop position is detected by an encoder, the difference between the actual stop position and the target stop position is calculated and stored, and the stored actual stop position and Based on the difference from the target stop position, the carrier position that is the starting point for applying the brake voltage to the DC motor is corrected, thereby reducing the change in the carrier stop position due to the change in the remaining amount of ink. It is possible to improve the accuracy of the carrier stop position, improve the printing quality, and reduce the size of the recording head maintenance means.

  According to the first aspect of the present invention, the motor control means calculates and stores the difference between the actual stop position of the carrier and the target stop position, and reflects it in the subsequent control of the DC motor. Position accuracy can be improved. In addition, since the processing for calculating the difference between the actual stop position of the carrier and the target stop position is performed when the ink jet printer is turned on or immediately after a predetermined number of sheets are printed, the print speed is almost the same. Has no effect. Therefore, it is possible to achieve both print quality and print speed. The recording head maintenance means is determined in consideration of the size of the recording head and the carrier stop position accuracy, so that the carrier stop position accuracy can be increased. It will be able to plan. Accordingly, it is easy to reduce the size of the printer. In carrier stop control, the motor control means applies a predetermined brake voltage to the DC motor until the carrier decelerates to the second speed, and thereafter stops the carrier by the resistance of the drive transmission means and the DC motor. Therefore, the carrier does not move in the reverse direction due to application of an excessive brake voltage.

  According to the invention of claim 2, since the motor control means calculates and stores the difference between the actual stop position of the carrier and the target stop position and reflects it in the subsequent control of the DC motor, the carrier stop Position accuracy can be improved. In addition, since the processing for calculating the difference between the actual stop position of the carrier and the target stop position is performed when the ink jet printer is turned on or immediately after a predetermined number of sheets are printed, the print speed is almost the same. Has no effect. Therefore, it is possible to achieve both print quality and print speed. The recording head maintenance means is determined in consideration of the size of the recording head and the carrier stop position accuracy, so that the carrier stop position accuracy can be increased. It will be able to plan. Accordingly, it is easy to reduce the size of the printer.

  An ink jet printer according to the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an inkjet printer. The ink jet printer 1 receives the driving force of the paper feed motor 2 and ejects ink onto the paper feed mechanism 4 that transports the recording paper P placed on the paper feed tray 3 into the apparatus main body and the transported recording paper P1. An ink cartridge 7 having a recording head 5 and an ink tank 6 for storing ink ejected from the recording head 5, a carrier 8 for detachably storing the ink cartridge 7, and a carrier driving motor 9 for driving the carrier 8. And an encoder 10 for detecting the position of the carrier 8 driven by the carrier drive motor 9, a motor control circuit (motor control unit) 11 for controlling the rotation of the paper feed motor 2 and the carrier drive motor 9, and the like. . The carrier 8 is slidably supported by a shaft 12 oriented in the main scanning direction orthogonal to the conveyance direction (sub-scanning direction) of the recording paper P, and is transmitted via a belt 13 (drive transmission means) or the like. The sliding movement is performed by the driving force of the driving motor 9. In the present embodiment, a low-cost DC (direct current) motor is applied as the carrier drive motor 9, and the position of the carrier 8 is detected by the encoder 10 provided along the movable region of the carrier 8. .

  FIG. 2 shows a configuration around the carrier 8. The belt 13 is suspended by a pulley 14 (drive transmission means) connected to the carrier drive motor 9, and the driving force of the carrier drive motor 9 is transmitted to the carrier 8 via the pulley 14 and the belt 13 in this order. . The encoder 10 includes a lattice plate 15 having a striped pattern formed at a predetermined interval in the main scanning direction of the carrier 8, a photo interrupter (not shown) provided on the back side of the carrier 8, and the like. The photo interrupter includes a light emitting unit that irradiates light to the grid plate 15 and a light receiving unit that receives light transmitted through the grid plate 15 or reflected by the grid plate 15 and converts it into an electrical signal. Since the grating plate 15 is formed with a striped pattern at a predetermined interval, a pulse signal corresponding to the striped pattern is output from the light receiving unit of the encoder 10 as the carrier 8 moves. A maintenance box 16 (recording head maintenance means) that performs maintenance of the recording head 5 is provided at a position facing the recording head 5 when the carrier 8 is positioned at the home position. The maintenance box 16 is configured to have a size that takes into account the change in the stop position of the carrier 8 with respect to the recording head 5.

  In the ink jet printer 1, an image is formed on the recording paper P <b> 1 by ejecting ink from the recording head 5 in conjunction with the sliding movement of the carrier 8. Therefore, in order to obtain good print quality, it is necessary to accurately control the stop position of the carrier 8. However, the stop position of the carrier 8 varies depending on the remaining amount of ink in the ink tank 6 and the temperature of the carrier drive motor 9 as described above, and may adversely affect the print quality. Therefore, in the present embodiment, the motor control circuit 11 calculates the correction value of the stop position of the carrier 8 based on the output of the encoder 10 when the inkjet printer 1 is turned on or immediately after printing a predetermined number of sheets. Then, it is reflected in the stop position control of the carrier 8 thereafter. The predetermined number of sheets to be continuously printed means a number of sheets that is empirically recognized that the carrier drive motor 9 generates heat so as to adversely affect the print quality and is at a high temperature. For example, in the ink jet printer 1 of the present embodiment, there are about 20 sheets, depending on the specifications of the motor to be used.

  FIG. 3 shows the transition of the speed of the carrier 8 when the correction value of the stop position of the carrier 8 is calculated. 4A shows the actual stop position of the carrier 8 when the brake start position and the ink remaining amount are large, and FIG. 4B shows the actual stop position when the brake start position is corrected. FIG. 5 shows the transition of the speed of the carrier 8 when the brake start position is corrected.

  First, the motor control circuit 11 moves the carrier 8 at the speed V1 (first speed) by applying a predetermined drive voltage to the carrier drive motor 9. This speed V1 is the moving speed of the carrier 8 during printing. Thereafter, the motor control circuit 11 applies a predetermined brake voltage to the carrier drive motor 9 so that the carrier 8 stops at the target stop position. The brake voltage is continuously applied until the carrier 8 is decelerated to the second speed V2. When the carrier 8 decelerates to the second speed, the brake voltage is turned off, and the carrier 8 is further decelerated by the resistances of the belt 13, the pulley 14, and the carrier drive motor 9, and stops. The reason why the application of the brake voltage is turned off immediately before the carrier 8 is stopped in this manner is that the output pulse from the encoder 10 immediately before the stop becomes rough, so that the brake voltage is excessively applied and the carrier 8 moves in the reverse direction. This is to prevent this.

  The deceleration of the carrier 8 when a brake voltage is applied to the carrier drive motor 9 varies depending on the remaining amount of ink and the temperature of the carrier drive motor 9. In FIG. 3, when the brake voltage is applied from the speed V1, the speed transition of the carrier 8 in the standard state is represented by VV1, whereas, for example, the speed of the carrier 8 in the state of being filled with ink. The transition is represented by VV2. As is clear from the figure, the braking effect is worse in the ink-filled state than in the standard state.

  As described above, as a result of the deterioration of the braking effect of the carrier 8, as shown in FIG. 4A, the carrier 8 moves by an extra distance X from the target stop position. In addition, this distance X is represented by the area shown by hatching in FIG. 3, and becomes the correction value of the stop position of the carrier 8 described above. In the present embodiment, the distance X is calculated when the power of the inkjet printer 1 is turned on or immediately after printing a predetermined number of sheets so as not to cause a decrease in printing speed. Then, in the carrier stop control at the time of executing the printing and the maintenance of the recording head, as shown in FIG. 4B, the carrier 8 which is the starting point for starting to apply the brake voltage to the carrier driving motor 9 according to the distance X. The stop position of the carrier 8 is corrected by correcting the position. That is, the motor control circuit 11 applies a brake voltage to the carrier drive motor 9 from a position just before the distance X while detecting the position of the carrier 8 based on the output signal of the encoder 10. As a result, the stop position of the carrier 8 is corrected, and the carrier 8 can be stopped substantially at the stop target position. As shown in FIG. 5, the time for the motor control circuit 11 to start applying the brake voltage to the carrier drive motor 9 is earlier than the standard state by a time ΔT obtained by dividing the distance X by the speed V1.

  As described above, according to the ink jet printer 1 of the present embodiment, the motor control circuit 11 calculates the difference between the actual stop position of the carrier 8 and the target stop position, that is, the distance X as a correction value, and calculates it. Since the data is stored and reflected in the subsequent control of the carrier drive motor 9, the accuracy of the stop position of the carrier 8 can be improved. The distance X calculation process is performed when the ink jet printer 1 is turned on or immediately after a predetermined number of prints are made, so that the print speed is hardly affected. Therefore, it is possible to achieve both print quality and print speed. In addition, the size of the maintenance box 16 is determined in consideration of the size of the recording head 5 and the stop position accuracy of the carrier 8, so that the stop position accuracy of the carrier 8 can be increased. Can be planned. As a result, the ink jet printer 1 can be easily downsized. In the stop control of the carrier 8, the motor control circuit 11 applies a predetermined brake voltage to the carrier drive motor 9 until the carrier 8 is decelerated to the second speed V2, and thereafter, the belt 13, the pulley 14, and the carrier Since the carrier 8 is stopped by the resistance of the drive motor 9, the carrier 8 does not move in the reverse direction due to application of an excessive brake voltage.

  The present invention is not limited to the configuration of the above-described embodiment. At least when the power is turned on, a correction value for the stop position of the carrier 8 is detected, and the correction value is used to control the carrier drive motor 9 during printing. It is only necessary to be configured to perform the above.

1 is a block diagram illustrating a configuration of an inkjet printer according to an embodiment of the present invention. The side view which shows the structure of the periphery of a carrier. The figure which shows transition of the speed of the carrier controlled by the motor control circuit at the time of calculating the correction value of the stop position of a carrier. (A) is a side view showing an actual stop position when the brake start position is corrected, and (b) is an actual stop position of the carrier when the remaining amount of ink is large. Diagram showing the change in carrier speed when the brake start position is corrected

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Paper feed motor 3 Paper feed tray 4 Paper feed mechanism 5 Recording head 6 Ink tank 7 Ink cartridge 8 Carrier 9 Carrier drive motor (DC motor)
10 Encoder 11 Motor control circuit (Motor control means)
16 Maintenance box (recording head maintenance means)

Claims (2)

An ink tank that stores ink, an ink cartridge having a recording head that discharges ink stored in the ink tank to form an image on recording paper, and supports the ink cartridge and is substantially orthogonal to the conveyance direction of the recording paper A carrier for conveying the carrier, a DC motor for driving the carrier, a drive transmission means for transmitting the driving force of the DC motor to the carrier, and a position of the carrier driven by the DC motor and the drive transmission means An encoder for detecting the motor, motor control means for controlling the DC motor based on a signal output from the encoder, and the carrier is disposed so as to face the recording head when positioned at the home position. And a recording head maintenance means for performing maintenance of the recording head. In the inkjet printer,
The motor control means includes
Calculate the position and velocity of the carrier based on the signal output from the encoder,
When the ink jet printer is turned on or immediately after printing a predetermined number of sheets, the carrier is moved at the first speed by applying a predetermined driving voltage to the DC motor, and then stopped at a target stop position. As described above, a predetermined brake voltage is applied until the carrier decelerates to the second speed, and then the carrier is stopped by the resistance of the drive transmission means and the DC motor,
The actual stop position is detected by the encoder, the difference between the actual stop position and the target stop position is calculated and stored,
A carrier position that is a starting point for applying a brake voltage to the DC motor based on a difference between the stored actual stop position and a target stop position in the stop control of the carrier at the time of printing and at the time of maintenance of the recording head. To reduce fluctuations in the remaining position of the carrier and fluctuations in the stop position of the carrier due to fluctuations in the temperature of the DC motor,
Thus, the accuracy of the carrier stop position is improved, and the print quality can be improved and the recording head maintenance means can be downsized. An ink tank that stores ink, an ink cartridge having a recording head that discharges ink stored in the ink tank to form an image on recording paper, and supports the ink cartridge and is substantially orthogonal to the conveyance direction of the recording paper A carrier for carrying the carrier, a DC motor for driving the carrier, an encoder for detecting the position of the carrier driven by the DC motor, and the DC motor based on a signal output from the encoder In an ink jet printer comprising: motor control means for controlling the recording head; and recording head maintenance means for maintaining the recording head, which is disposed so as to face the recording head when the carrier is positioned at a home position.
The motor control means includes
Calculate the position and velocity of the carrier based on the signal output from the encoder,
When the ink jet printer is turned on, a predetermined drive voltage is applied to the DC motor to move the carrier at a predetermined speed, and then a predetermined brake voltage is applied to stop at the target stop position. Stop the career,
The actual stop position is detected by the encoder, the difference between the actual stop position and the target stop position is calculated and stored,
Based on the difference between the stored actual stop position and the target stop position, the carrier position that is the starting point for applying the brake voltage to the DC motor is corrected, so that the stop position of the carrier accompanying the change in the remaining amount of ink. Less fluctuations,
Thus, the accuracy of the carrier stop position is improved, and the print quality can be improved and the recording head maintenance means can be downsized.

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