JP2006341380A - Ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet printer in which precision of a correction value can be enhanced by smoothing the measurement error of sheet end position in print start position correction processing, and good print results can be attained easily and surely regardless of individual sheet displacement among products by determining the correction value automatically and correcting the print start position. <P>SOLUTION: During print start position correction processing, a control section controls an alignment sensor 6 to measure the end of a sheet P and calculates a correction value based on the position of a carrier 3 measured by a carrier encoder 5 at that time. Average value of the correction value thus calculated and a previous correction value stored in a memory of the control section is then determined. That average value is employed as a true correction value, and print operation is performed based on the true correction value which is then stored in the memory as a previous correction value. Every time when the treatment for correction of print start position is repeated, the previous correction value is read out and the true correction value is determined. Consequently, measurement error of sheet end position is smoothed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet printer that prints on paper by a print head mounted on a reciprocating carrier.

  In general, as one of output devices such as computers and workstations, a DC motor is used to reciprocate a carrier mounted with a print head in a main scanning direction perpendicular to the sub-scanning direction in which the paper is conveyed. Inkjet printers that print on the printer are used. In such an ink jet printer, when the paper is transported, the paper position may deviate from a predetermined state. However, in order to obtain a good printing result even if the paper is misaligned, A technique for correcting the printing position and printing has been proposed.

  As an ink jet printer as described above, for example, as disclosed in Patent Document 1, the position of the paper is calculated by detecting the left and right edges of the paper with a paper edge detection sensor attached in the vicinity of the carrier. Thus, there is known one that controls a printing operation so that printing is performed within a predetermined position of a calculated sheet. In this inkjet printer, for each sheet fed, that is, for each printing operation, the carrier on which the sheet end detection sensor is mounted moves in the main scanning direction, and the position of the carrier when the sheet end detection sensor detects the sheet end. Is detected by the carrier encoder, and the position and inclination of the paper are calculated by one sensor. Then, printing is performed from the printing start position calculated using the position and inclination values as correction values, and printing is performed by deleting printing outside the paper range.

  In addition, in an ink jet printer that performs printing using a plurality of types of ink, an ink cartridge may be independently attached to the carrier for each ink. At this time, the mounting position of each ink cartridge may vary. When the ink cartridge is provided with a nozzle, there is a problem that the printing position by each ink is slightly shifted due to this variation, and the printing quality is deteriorated. Conventionally, in order to solve this problem, for example, as shown in Patent Document 2 as a conventional technique, a test pattern is printed with each ink, and this test pattern is read by an alignment sensor attached to a carrier. An amount of deviation of the ink print position is detected, and the print position is corrected by a correction value based on the detection result. Patent Document 2 discloses a technique in which this alignment sensor is also used as a media sensor for detecting the type of paper.

  By the way, the paper misalignment is different for each product even in the same type of ink jet printer, such as a slight assembly error at the time of assembling the product and an error for each cartridge of the nozzle position provided in the ink cartridge. Some are caused by various factors. Conventionally, such a paper misalignment has been manually adjusted at the time of manufacturing the printer, such as actually printing, measuring the amount of misalignment of the paper, and inputting a correction value. However, this operation is very troublesome, and is an obstacle to improving manufacturing efficiency.

According to the technique described in the above-mentioned Patent Document 1, it is possible to cope with the paper misalignment caused by different factors for each product described above. However, this technique detects the paper misalignment for each printing operation. Since the printing process is complicated, printing may take time. In addition, since this technique calculates the print start position by measuring the position and inclination of the paper only once for each print operation, an error may occur in the print start position. Note that the technique described in Patent Document 2 described above does not detect the edge of the paper, and this technique cannot detect and correct paper misalignment.
Japanese Patent Laid-Open No. 9-24653 Noto 3089578

  The present invention has been made in view of the above problems, and it is possible to smooth the measurement error of the position of the sheet edge and increase the accuracy of the correction value. An object of the present invention is to provide an ink jet printer capable of automatically obtaining a correction value and correcting a printing start position and easily and reliably obtaining a good printing result.

  In order to achieve the above object, the invention of claim 1 is equipped with a paper transport mechanism for transporting paper in the sub-scanning direction, and a print head for discharging a plurality of types of ink from nozzles to print on the paper. A carrier that is reciprocated in the main scanning direction orthogonal to the scanning direction, a DC motor that drives the carrier, a motor driver that controls the DC motor, and a carrier attached to the carrier. A carrier encoder that scans an encoder strip that is arranged along the main scanning direction and has slits provided at predetermined intervals, outputs a pulse signal, and measures the position of the carrier in the main scanning direction, and is attached to the carrier. A light emitting element that emits light toward the paper, and a light receiving element that receives light from the light emitting element reflected on the paper. An alignment sensor capable of measuring the position printed on the paper by scanning the paper according to the reciprocating movement of the carrier, and a memory for storing data used for the printing operation. Control for performing printing operation for printing data sent from the computer, and performing auto-alignment processing for adjusting in advance so that printing by the print head is appropriate when a predetermined command is sent from an external computer And the control unit determines the position of the carrier in the main scanning direction with respect to the paper based on a pulse signal output from the carrier encoder and a predetermined correction value set in a normal printing process. And the print start position by the print head is controlled to be a predetermined position from the end of the paper. During the alignment process, the carrier is moved and a predetermined test pattern is printed on the paper by the print head, and then the carrier is moved again and the alignment sensor is scanned over the test pattern to print the test pattern. In the ink jet printer configured to measure the position and control the printing operation by the print head so that the printing position of each of the plurality of types of ink is an appropriate position based on the measurement result, the control unit includes: During the auto alignment process, the carrier is moved to cause the alignment sensor to measure the edge of the paper, and the print start position correction process is performed to calculate the correction value based on the carrier position measured by the carrier encoder at that time. In addition to performing a printing operation based on this correction value, This correction value is stored in the memory as the previous correction value, and when the print start position correction process is performed again, the alignment sensor measures the paper edge and calculates based on the carrier position measured by the carrier encoder. The average of the corrected value and the previous correction value read from the memory is set as the true correction value, and the printing operation is performed based on the true correction value, and the true correction value is set as the previous correction value. To remember.

  According to a second aspect of the present invention, a paper transport mechanism that transports paper in the sub-scanning direction and a print head that ejects ink from nozzles and prints on the paper are mounted, and reciprocates in the main scanning direction perpendicular to the sub-scanning direction. A carrier to be moved, a DC motor for driving the carrier, a motor driver for controlling the DC motor, and a carrier attached to the carrier, and arranged along the main scanning direction according to the reciprocating movement of the carrier. A carrier encoder that scans an encoder strip having slits provided at predetermined intervals to output a pulse signal and measures the position of the carrier in the main scanning direction, and a light emitting element that is attached to the carrier and emits light toward the paper And a light-receiving element that receives light from the light-emitting element reflected on the paper, and moves forward according to the reciprocation of the carrier. A print that prints data sent from an external computer, and has an alignment sensor that can measure the position printed on the paper by scanning the paper and a memory that stores data used for the print operation A control unit that controls the operation, and the control unit calculates a position of the carrier in the main scanning direction with respect to the paper based on a pulse signal output from the carrier encoder and a predetermined correction value set in advance. In the ink jet printer configured to control the print start position by the print head to be a predetermined position from the sheet edge, the control unit moves the carrier and causes the alignment sensor to measure the sheet edge. The print start position for calculating the correction value based on the position of the carrier measured by the carrier encoder at that time When the correction processing is performed and the printing operation is performed based on the correction value, the correction value is stored in the memory as the previous correction value, and the print start position correction processing is performed again, the alignment sensor The average of the correction value calculated based on the carrier position measured by the carrier encoder and the previous correction value read from the memory is set as the true correction value, and the printing operation is performed based on the true correction value. And the true correction value is stored in the memory as the previous correction value.

  According to a third aspect of the present invention, in the second aspect of the invention, the control unit performs the print start position correction process when a predetermined command is sent from an external computer.

  According to the first aspect of the invention, the correction value is obtained by performing the print start position correction process, the obtained correction value is stored in the memory, and the average of the result of the re-measurement of the paper position and the stored correction value is obtained. Since the calculation of the correction value is repeated, the measurement error can be smoothed to increase the accuracy of the correction value, and a good print result can be obtained with certainty. In addition, since the position of the paper is measured using an alignment sensor for scanning the test pattern in the auto alignment process, a correction value is automatically obtained and the print start position is determined without the need for a dedicated sensor. Correction can be performed, and a good printing result can be obtained easily and inexpensively. Since this print start position correction process is performed during auto-alignment processing by sending a predetermined command from an external computer, it is possible to operate the print start position correction process appropriately and easily in a short time. Thus, the usability of the ink jet printer is improved.

  According to the second aspect of the invention, the print start position correction process is performed to obtain a correction value, the obtained correction value is stored in the memory, the result of re-measuring the paper position and the average of the stored correction value is obtained and the true value is obtained. Since the calculation of the correction value is repeated, the accuracy of the correction value can be increased as described above. Further, since the correction value is automatically calculated, a good print result can be obtained easily and reliably.

  According to the invention of claim 3, since the control unit performs the print start position correction process when a predetermined command is sent from an external computer, the print start position correction process can be operated appropriately and easily. This makes it possible to improve the usability of the inkjet printer.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show an ink jet printer according to the present embodiment. The ink jet printer 1 is reciprocally moved in a main scanning direction (black arrow direction in the figure) perpendicular to the sub-scanning direction and a paper conveyance mechanism 2 that conveys the paper P in the sub-scanning direction (white arrow direction in the figure) A carrier 3 on which a print head 3 a for printing on the paper P is mounted, a DC motor 4 for driving the carrier 3, a motor driver 4 a for controlling the DC motor 4, and attached to the carrier 3. Thus, the carrier encoder 5 that scans the encoder strip 5a arranged along the main scanning direction on the frame of the ink jet printer 1 and the carrier 3 are arranged so as to scan the paper P according to the reciprocating movement of the carrier 3. The alignment sensor 6 and the controller 7 are provided.

  The print head 3a mounted on the carrier 3 prints on the paper by ejecting a plurality of types of ink from the nozzles. In the present embodiment, for example, a plurality of types of ink are stored in independent cartridges (not shown) provided with nozzles, and this cartridge is mounted on the carrier 3 so as to print as the print head 3a. However, it is not limited to this. In the inkjet printer 1, the carrier 3 is driven by the DC motor 4 to reciprocate in the main scanning direction, and the print head 3a drops ink or the like onto the paper P transported by the paper transport mechanism 2 by a predetermined width. As a result, the image is recorded on the paper P.

  The carrier encoder 5 and the encoder strip 5a are used to control the printing operation by controlling the movement of the carrier 3. The encoder strip 5a is such that slits at equal intervals are cut at 150 dpi, for example. The carrier encoder 5 scans the encoder strip 5a according to the reciprocation of the carrier 3, and outputs, for example, two-phase pulse signals that are out of phase with each other. That is, this pulse signal is output according to the movement of the carrier 3. The controller 7 calculates the position and speed of the carrier 3 based on the count number of the pulse signal, the interval between pulses, and the like. That is, the carrier encoder 5 measures the position of the carrier 3 in the main scanning direction by outputting a pulse signal.

  The alignment sensor 6 is provided on the carrier 3 so as to face the paper P below the carrier 3. The alignment sensor 6 includes a light emitting element (not shown) that emits light toward the paper P and a light receiving element (not shown) that receives light from the light emitting element reflected on the paper P. The light reflectance of the light emitting element is different between the non-printed part on the paper P and the printed part. For this reason, when the alignment sensor 6 scans the paper P, the position printed on the paper P by the position of the carrier 3 in the main scanning direction measured by the carrier encoder 5 and the intensity of light received by the light receiving element. It is possible to measure.

  The control unit 7 is an ASIC (Application Specific Integrated Circuit) configured for an inkjet printer, and includes a CPU 7a and a memory 7b that can communicate with the CPU 7a. The memory 7b is composed of a ROM and a RAM, and stores data used for the printing operation. In the present embodiment, the memory 7b also includes, for example, an EEPROM or the like, and stores a rewritable correction value for correcting the position of the carrier 3 with respect to the position of the paper P as will be described later. As will be described later, this correction value is calculated by a print start position correction process. In the present embodiment, in a state immediately after the manufacture of the inkjet printer 1, for example, a predetermined fixed value set in advance is stored as the correction value, but the present invention is not limited to this. The CPU 7a of the control unit 7 communicates with the memory 7b to operate the firmware, thereby performing a printing operation for printing data sent from the external computer 10, an operation for detecting the home position of the carrier 3, and a later-described operation. Thus, it is configured to control various operations of the ink jet printer 1 such as an auto-alignment process in which the printing by the print head 3a is adjusted so as to be appropriate.

  Next, an example of the normal operation of the inkjet printer 1 will be described. When the power is turned on, the control unit 7 of the ink jet printer 1 performs an operation of detecting a predetermined home position of the carrier 3. When detecting the home position of the carrier 3, the control unit 7 can detect the position of the carrier 3 with respect to the home position by counting the pulse signal output from the carrier encoder 5 in accordance with the movement of the carrier 3. Then, the control unit 7 operates the paper transport mechanism 2 to transport the paper in the sub-scanning direction based on the print data sent from the external computer 10 or workstation, and also moves the carrier 3 in the main scanning direction. A printing operation is performed by operating the print head 3a while moving it.

  Here, when performing the printing operation as described above, the control unit 7 calculates the position of the carrier 3 with respect to the paper P using the correction value stored in the memory 7b. The correction value is a value corresponding to the difference between the position in the main scanning direction with respect to the home position of the carrier 3 measured by the carrier encoder 5 and the position in the main scanning direction of the carrier 3 with respect to the conveyed paper P. Is a value indicating the position of the paper edge with respect to. That is, the control unit 7 calculates the position of the carrier 3 in the main scanning direction with respect to the paper P based on the pulse signal output from the carrier encoder 5 and the correction value, and the print start position by the print head 3a is the paper start position. The printing operation is performed by controlling to be a predetermined position from the end.

  Furthermore, the above-described auto-alignment process will be described as an example of another operation performed by the control unit 7 in addition to the normal printing operation as described above. The auto-alignment process is automatically performed, for example, when a new ink cartridge is mounted on the inkjet printer 1, or when an external computer is used at the time of manufacturing the inkjet printer 1 or the user's operation after shipment. 10 or the like is sent by a predetermined command. In this auto-alignment process, it is checked whether or not the print positions of a plurality of types of ink are appropriate positions, and the print operation of the print head 3a is controlled so as to be at appropriate positions.

  In the auto-alignment process, the control unit 7 first moves the carrier 3 and prints a predetermined test pattern on the paper P by the print head 3a. Then, the carrier 3 is moved again, the alignment sensor 6 is scanned over the test pattern, and the print position of the test pattern is measured as described above. Based on the measurement result, the printing operation by the print head 3a is controlled so that the printing positions of the plurality of types of inks are appropriate.

  Here, in the present embodiment, when the inkjet printer 1 is manufactured, the print start position correction process is performed when the above-described auto alignment process is performed. This print start position correction process is performed by the control unit 7 and causes the alignment sensor 6 to measure the end (sheet end) of the sheet P, and based on the position of the carrier 3 measured by the carrier encoder 5 at the sheet end. The above correction value is automatically calculated. In the inkjet printer 1, the position of the paper P to be fed in the main scanning direction is slightly different for each product due to manufacturing errors and the like. In the present embodiment, this print start position correction process is performed for each individual product before shipment, so that a correction value suitable for each individual product is calculated and the position printed on the paper is the same. It is made to become. Note that this print start position correction processing is not limited to that performed at the factory or the like before shipment of the product as described above, but when an ink cartridge is mounted after shipment or when the user operates the external computer 10 or the like. It may also be performed at the time of the automatic alignment process.

  FIG. 3 shows a processing procedure of the print start position correction process. When the control unit 7 causes the alignment sensor 6 to scan the test pattern printed on the paper P in the above-described auto-alignment process, the control unit 7 moves the carrier 3 in a wider range, not limited to the range on the paper P. The end of the main operation direction side of P is also scanned by the alignment sensor 6. When the alignment sensor 6 scans the boundary of the edge of the paper P, the intensity of light received by the light receiving element changes abruptly on the boundary. Therefore, the value output from the alignment sensor 6 is measured and recognized as a paper edge when it suddenly changes (S1), and the value of the carrier encoder 5 at that time is measured to determine the position of the carrier 3 as described above. Measure (S2). At this time, the position of the sheet edge with respect to the home position is measured, and the control unit 7 calculates the correction value of the print start position from the measurement results of the alignment sensor 6 and the carrier encoder 5 (S3).

  When calculating the correction value, if the control unit 7 calculates the first correction value after the manufacture of the inkjet printer 1, the control unit 7 controls the printing operation based on the correction value as described above. Then, this correction value is recorded in the memory 7b of the control unit 7 as the previous correction value instead of the predetermined fixed value stored in advance. Then, after the correction value is obtained for the first time after manufacturing as described above, when the print start position correction process is performed again, the true correction value is calculated as follows using the previous correction value stored in the memory 7b. .

  First, the above-described processes of S1, S2, and S3 are performed, and correction values are similarly calculated. Then, the previous correction value is read from the memory 7b (S4). Then, an average value of the correction value calculated in S3 and the previous correction value read from the memory 7b is obtained, and this average value is set as a true correction value (S5). When the true correction value is obtained, the true correction value is stored in the memory 7b as the previous correction value, and the printing operation is performed based on the true correction value.

  Thereafter, when the print start position correction process is performed again, the average value of the previous correction value stored in the memory 7b and the correction value measured and calculated at that time is obtained as the true correction value. The printing operation is performed based on the true correction value.

  As described above, the average value of the previous correction value and the correction value measured and calculated at that time is obtained as the true correction value, so that the measurement error is included in the correction value measured and calculated each time. Even if it is, the true correction value is obtained by smoothing the measurement error, and the accuracy as the correction value is increased. By increasing the accuracy of the correction value, it is possible to reliably obtain a good print result.

  Further, since the position of the paper P is measured by using the alignment sensor 6 for scanning the test pattern in the auto alignment process, the correction value is automatically obtained and printing is started without the need for a dedicated sensor. The position can be corrected, and good print results can be obtained easily and inexpensively. Since this print start position correction process is performed during auto-alignment processing by sending a predetermined command from the external computer 10, the print start position correction process can be operated appropriately and easily in a short time. This makes it possible to improve the usability of the inkjet printer 1.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, the print start position correction process is not performed during the auto-alignment process as described above, and may be performed independently. For example, it is assumed that the correction value is obtained as described above without printing and scanning the test pattern by sending a predetermined command from the external computer 10 or the like at the time of manufacturing in a factory. At this time, the printing start position correction process is repeated, and the true correction value is calculated as the average value of the previous correction value and the correction value measured and calculated at that time, as described above. Thus, it is possible to easily and reliably obtain a highly accurate correction value.

1 is a perspective view showing an ink jet printer according to an embodiment of the present invention. The block diagram which shows the structure of an inkjet printer same as the above. The flowchart which shows the procedure of the printing start position correction process of an inkjet printer same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Paper conveyance mechanism 3 Carrier 3a Print head 4 DC motor 4a Motor driver 5 Carrier encoder 5a Encoder strip 6 Alignment sensor 7 Control part 7b Memory 10 Computer

Claims (3)

A paper transport mechanism for transporting paper in the sub-scanning direction;
A print head that discharges a plurality of types of ink from nozzles and prints on the paper is mounted, and a carrier that reciprocates in a main scanning direction orthogonal to the sub-scanning direction;
A DC motor for driving the carrier;
A motor driver for controlling the DC motor;
A pulse signal is output by scanning an encoder strip attached to the carrier and having slits arranged along the main scanning direction and provided at predetermined intervals according to the reciprocating movement of the carrier. A carrier encoder that measures the position in the direction;
A light-emitting element that is attached to the carrier and emits light toward the paper and a light-receiving element that receives light from the light-emitting element reflected on the paper, and scans the paper according to the reciprocating movement of the carrier An alignment sensor that can measure the position printed on the paper,
The print head has a memory for storing data used for a printing operation, and controls the printing operation for printing data sent from an external computer, and the print head when a predetermined command is sent from the external computer A control unit that performs an auto-alignment process to adjust in advance so that the printing by
The control unit calculates a position of the carrier in the main scanning direction with respect to the paper based on a pulse signal output from the carrier encoder and a predetermined correction value set in advance during normal printing processing, Control the print start position by the head to be a predetermined position from the edge of the paper,
Further, during the auto alignment process, the carrier is moved and a predetermined test pattern is printed on the paper by the print head, and then the carrier is moved again and the alignment sensor is scanned over the test pattern. In the ink jet printer configured to control the printing operation by the print head so that the printing position of each of the plurality of types of ink is an appropriate position based on the measurement result.
The control unit moves the carrier during the auto-alignment process, causes the alignment sensor to measure the paper edge, and calculates the correction value based on the position of the carrier measured by the carrier encoder at that time A correction process is performed, a printing operation is performed based on the correction value, and the correction value is stored in the memory as a previous correction value.
When the print start position correction process is performed again, the average of the correction value calculated based on the carrier position measured by the carrier encoder measured by the alignment sensor and the previous correction value read from the memory is calculated. An ink jet printer, wherein a true correction value is set, a printing operation is performed based on the true correction value, and the true correction value is stored in the memory as a previous correction value. A paper transport mechanism for transporting paper in the sub-scanning direction;
A print head that ejects ink from nozzles to print on the paper, and a carrier that reciprocates in a main scanning direction orthogonal to the sub-scanning direction;
A DC motor for driving the carrier;
A motor driver for controlling the DC motor;
A pulse signal is output by scanning an encoder strip attached to the carrier and having slits arranged along the main scanning direction and provided at predetermined intervals according to the reciprocating movement of the carrier. A carrier encoder that measures the position in the direction;
A light-emitting element that is attached to the carrier and emits light toward the paper and a light-receiving element that receives light from the light-emitting element reflected on the paper, and scans the paper according to the reciprocating movement of the carrier An alignment sensor that can measure the position printed on the paper,
A memory for storing data used for the printing operation, and a control unit for controlling the printing operation for printing data sent from an external computer;
The control unit calculates a position of the carrier in the main scanning direction with respect to the paper based on a pulse signal output from the carrier encoder and a predetermined correction value set in advance, and a print start position by the print head is determined. In an inkjet printer configured to be controlled so as to be a predetermined position from the paper edge,
The controller moves the carrier, causes the alignment sensor to measure the edge of the paper, and performs a print start position correction process for calculating the correction value based on the position of the carrier measured by the carrier encoder at that time. A printing operation is performed based on the correction value, and this correction value is stored in the memory as the previous correction value.
When the print start position correction process is performed again, the average of the correction value calculated based on the carrier position measured by the carrier encoder measured by the alignment sensor and the previous correction value read from the memory is calculated. An ink jet printer, wherein a true correction value is set, a printing operation is performed based on the true correction value, and the true correction value is stored in the memory as a previous correction value. The ink jet printer according to claim 2, wherein the control unit performs the print start position correction process when a predetermined command is sent from an external computer.

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