JP2005193493A - Printer, method of printing, program, and printing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in quality of a printed image by switching a printing method based on a detected result by a sensor. <P>SOLUTION: This printer has a moving body for moving an ink ejection section for ejecting ink to a medium and a sensor for detecting the change of a gap between the medium and the ink ejection section, and forms dots on the medium by ejecting the ink from the ink ejection section by a plurality of printing methods. The printing method is switched based on the detected result by the sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing apparatus, a printing method, a program, and a printing system.

2. Description of the Related Art There is known an ink jet printer that includes a head that ejects ink onto paper and that performs printing by ejecting ink from the head to form dots on the paper. In such an ink jet printer, a gap is provided between the head and the paper so that the head can move relative to the paper. Then, the ink ejected from the head flies through this gap and land on the paper, forming dots on the paper.
In such a printer, when the distance between the paper and the head changes, the ink landing position is shifted. Therefore, an interval between the paper and the head is detected, and ink ejection timing is controlled based on the detection result (see Patent Document 1).
JP 2003-266651 A

However, even if the ink ejection timing is controlled based on the detection result of the distance between the paper and the head, it is difficult to completely eliminate the ink landing position error. For example, if the position of the nozzle for ejecting ink is different from the interval detection position, an error may occur between the interval between the nozzle for ejecting ink and the paper and the detection result, and the ink landing position may shift. If there is an error in the ink landing position, the image quality of the printed image is degraded.
SUMMARY An advantage of some aspects of the invention is that the printing method is switched based on the detection result of the sensor to alleviate the deterioration of the image quality of the printed image.

A main invention for achieving the above object includes a moving body that moves an ink discharge section that discharges ink onto a medium, and a sensor that can detect a change in the interval between the medium and the ink discharge section. In the printing apparatus, the ink is ejected from the ink ejection unit to form dots on the medium, and the printing system is switched based on the detection result of the sensor.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  The printing method can be switched based on the detection result of the sensor, and deterioration of the image quality of the printed image can be alleviated.

=== Summary of disclosure ===
At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A moving body that moves an ink discharge section that discharges ink onto a medium;
A sensor capable of detecting a change in an interval between the medium and the ink ejection unit;
With
A printing apparatus that forms dots on the medium by discharging the ink from the ink discharge unit using a plurality of printing methods,
A printing apparatus that switches the printing method based on a detection result of the sensor.
According to such a printing apparatus, it is possible to mitigate image quality degradation.

  In this printing apparatus, it is preferable that the sensor is movable together with the moving body. Thereby, the sensor can detect the space | interval of paper and a head not only in one place but in several places.

  In this printing apparatus, the ink ejection unit includes a plurality of nozzles arranged along the transport direction, and the sensor is provided on the upstream side in the transport direction with respect to the nozzle on the most downstream side in the transport direction. It is desirable. Thereby, it is possible to avoid the possibility that the medium comes into contact with the ink discharge portion.

  In this printing apparatus, it is preferable that the sensor is provided on a platen that supports the medium. Thereby, the wiring to a moving body can be reduced.

  In this printing apparatus, it is preferable that the ink ejection unit has a plurality of nozzles, and the number of nozzles used when forming one raster line in the plurality of printing methods is different. In addition, it is preferable that the printing method after switching has a larger number of nozzles used when forming one raster line than the printing method before switching. According to such a printing apparatus, the image quality can be improved.

  In this printing apparatus, it is preferable that the printing apparatus further includes an adjustment mechanism that adjusts a distance between the medium and the ink discharge unit, and the adjustment mechanism is driven at a timing different from a timing at which the printing method is switched. Thereby, deterioration of the image quality of the entire printed image can be suppressed.

  In this printing apparatus, it is preferable that the plurality of printing methods have different transport amounts for transporting the medium, and drive the adjustment mechanism at a timing different from the timing at which the transport amount is switched. Thereby, deterioration of the image quality of the entire printed image can be suppressed.

  In such a printing apparatus, it is preferable that a transition process is performed during the switching when the printing method is switched, and the adjustment mechanism is driven after the transition process. As a result, it is possible to suppress deterioration of the image quality of the entire printed image.

  In this printing apparatus, a first area printed by a printing method before switching and a second area printed by a printing method after switching are formed on the medium, and the ink is driven after the adjustment mechanism is driven. The area where the ejection unit performs printing is preferably the second area. As a result, it is possible to suppress deterioration of the image quality of the entire printed image.

  In this printing apparatus, it is preferable that a transition region is formed between the first region and the second region, and the adjustment mechanism is driven after the transition region is formed. As a result, it is possible to suppress deterioration of the image quality of the entire printed image.

  In this printing apparatus, it is preferable that the printing apparatus further includes a transport roller and a paper discharge roller, and the adjustment mechanism is driven when only one of the transport roller and the paper discharge roller is transporting the medium. Thereby, it is possible to prevent the medium from coming into contact with the ink discharge portion.

  In this printing apparatus, the first threshold value and the second threshold value are stored, and when the detection result of the sensor exceeds the first threshold value, the printing method is switched, and the detection result of the sensor indicates the second threshold value. When exceeded, it is desirable to drive the adjustment mechanism. Degradation of the image quality of the entire printed image can be suppressed.

  In such a printing apparatus, a predetermined threshold value is stored, a time when the detection result of the sensor exceeds the predetermined threshold value is predicted based on a history of detection results of the sensor, and based on the prediction result, It is desirable to switch the printing method and drive the adjustment mechanism when the detection result of the sensor exceeds the predetermined threshold value. Degradation of the image quality of the entire printed image can be suppressed.

  In this printing apparatus, the ink ejection unit includes a plurality of nozzles, transmits a detection result of the sensor to an external apparatus, receives print data from the external apparatus, and each nozzle is based on the print data. It is desirable to eject ink from the ink to form dots on the medium. Thereby, the external device can generate print data corresponding to the switching of the printing method based on the detection result of the sensor.

  In this printing apparatus, the ink ejection unit includes a plurality of nozzles, generates pixel data by rearranging pixel data in a matrix form of image data in accordance with the arrangement of the nozzles, and generates the print data. Based on this, ink may be ejected from each nozzle to form dots on the medium. The printing apparatus preferably generates the print data based on the detection result of the sensor. Thereby, the rasterizing process can be performed on the printing apparatus side.

Ink is ejected from the ink ejection unit in the first printing method to form dots on the medium,
Detecting a change in an interval between the medium and the ink ejection unit;
Based on the detection result, switching from the first printing method to the second printing method,
A printing method, comprising: ejecting ink from the ink ejection unit by the second printing method to form dots on the medium.
According to such a printing method, deterioration in image quality can be alleviated.

A moving body that moves an ink discharge section that discharges ink onto a medium;
A sensor capable of detecting a change in an interval between the medium and the ink ejection unit;
In a printing device equipped with
A function of ejecting the ink from the ink ejection unit by a plurality of printing methods to form dots on the medium;
A program that realizes a function of switching the printing method based on a detection result of the sensor.
According to such a program, deterioration in image quality can be alleviated.

A printing device and a computer;
The printing apparatus includes a moving body that moves an ink ejection unit that ejects ink onto a medium, and a sensor that can detect a change in the interval between the medium and the ink ejection unit.
A printing system that ejects the ink from the ink ejection unit in a plurality of printing methods to form dots on the medium,
A printing system, wherein the printing method is switched based on a detection result of the sensor.
According to such a printing system, it is possible to mitigate image quality degradation.

=== Configuration of Printing System ===
Next, an embodiment of a printing system (computer system) will be described with reference to the drawings. However, the description of the following embodiments includes embodiments relating to a computer program and a recording medium on which the computer program is recorded.

  FIG. 1 is an explanatory diagram showing an external configuration of a printing system. The printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140. The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. The computer 110 is electrically connected to the printer 1 and outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image. The display device 120 has a display and displays a user interface such as an application program or a printer driver. The input device 130 is, for example, a keyboard 130A or a mouse 130B, and is used for operating an application program, setting a printer driver, or the like along a user interface displayed on the display device 120. As the recording / reproducing device 140, for example, a flexible disk drive device 140A or a CD-ROM drive device 140B is used.

  A printer driver is installed in the computer 110. The printer driver is a program for realizing the function of displaying the user interface on the display device 120 and the function of converting the image data output from the application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.

  The “printing apparatus” means the printer 1 in a narrow sense, but means a system of the printer 1 and the computer 110 in a broad sense.

=== Printer driver ===
<About the printer driver>
FIG. 2 is a schematic explanatory diagram of basic processing performed by the printer driver. The components already described are given the same reference numerals, and the description thereof is omitted.
In the computer 110, computer programs such as a video driver 112, an application program 114, and a printer driver 116 operate under an operating system installed in the computer. The video driver 112 has a function of displaying, for example, a user interface on the display device 120 in accordance with display commands from the application program 114 and the printer driver 116. The application program 114 has a function of performing image editing, for example, and creates data related to an image (image data). The user can give an instruction to print an image edited by the application program 114 via the user interface of the application program 114. Upon receiving a print instruction, the application program 114 outputs image data to the printer driver 116.

  The printer driver 116 receives image data from the application program 114, converts the image data into print data, and outputs the print data to the printer. Here, the print data is data in a format that can be interpreted by the printer 1, and is data having various command data and pixel data. Here, the command data is data for instructing the printer to execute a specific operation. The pixel data is data relating to pixels constituting an image to be printed (printed image). For example, data relating to dots formed at positions on the paper corresponding to a certain pixel (such as dot color and size). Data).

  The printer driver 116 performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, and the like in order to convert image data output from the application program 114 into print data. Hereinafter, various processes performed by the printer driver 116 will be described.

  The resolution conversion process is a process of converting image data (text data, image data, etc.) output from the application program 114 into a resolution for printing on paper. For example, when the resolution for printing an image on paper is specified as 720 × 720 dpi, the image data received from the application program 114 is converted into image data having a resolution of 720 × 720 dpi. Note that the image data after the resolution conversion process is multi-gradation (for example, 256 gradations) RGB data represented by an RGB color space. Hereinafter, RGB data obtained by performing resolution conversion processing on image data is referred to as RGB image data.

  The color conversion process is a process for converting RGB data into CMYK data represented by a CMYK color space. The CMYK data is data corresponding to the ink color of the printer. This color conversion processing is performed by the printer driver 116 referring to a table (color conversion lookup table LUT) in which gradation values of RGB image data and gradation values of CMYK image data are associated with each other. Through this color conversion process, RGB data for each pixel is converted into CMYK data corresponding to the ink color. The data after the color conversion processing is CMYK data with 256 gradations represented by the CMYK color space. Hereinafter, CMYK data obtained by performing color conversion processing on RGB image data is referred to as CMYK image data.

  The halftone process is a process for converting high gradation number data into gradation number data that can be formed by a printer. For example, data representing 256 gradations is converted into 1-bit data representing 2 gradations or 2-bit data representing 4 gradations by halftone processing. In the halftone process, pixel data is created by using a dither method, γ correction, error diffusion method, or the like so that the printer can form dots dispersedly. When performing halftone processing, the printer driver 116 refers to a dither table when performing a dither method, refers to a gamma table when performing γ correction, and refers to a diffused error when performing an error diffusion method. Refer to the error memory for storage. The data subjected to the halftone process has a resolution (for example, 720 × 720 dpi) equivalent to the RGB data described above. The halftoned data is composed of 1-bit or 2-bit data for each pixel, for example. Hereinafter, of the halftone processed data, 1-bit data is referred to as binary data, and 2-bit data is referred to as multi-value data. The halftone processed image data is composed of a matrix pixel data group.

  The rasterization process is a process of rearranging the matrix pixel data group in the order of data to be transferred to the printer. That is, the rasterizing process is a process of rearranging the pixel data in the matrix form of the image data in accordance with the nozzle arrangement. The rasterized data is output to the printer as pixel data included in the print data.

=== Configuration of Printer ===
<Inkjet printer configuration>
FIG. 3 is a block diagram of the overall configuration of the printer of this embodiment. FIG. 4 is a schematic diagram of the overall configuration of the printer of this embodiment. FIG. 5 is a cross-sectional view of the overall configuration of the printer of this embodiment. Hereinafter, the basic configuration of the printer of this embodiment will be described.

  The printer of this embodiment includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and a controller 60. In addition, the printer of this embodiment includes a PG adjustment mechanism 70. The printer 1 that has received print data from the computer 110, which is an external device, controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and forms an image on paper. The situation in the printer 1 is monitored by a detector group 50, and the detector group 50 outputs a detection result to the controller 60. The controller 60 that receives the detection result from the detector group 50 controls each unit based on the detection result.

  The transport unit 20 is for feeding a medium (for example, the paper S) to a printable position and transporting the paper by a predetermined transport amount in a predetermined direction (hereinafter referred to as a transport direction) during printing. That is, the transport unit 20 functions as a transport mechanism (transport means) that transports paper. The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. However, in order for the transport unit 20 to function as a transport mechanism, all of these components are not necessarily required. The paper feed roller 21 is a roller for automatically feeding the paper inserted into the paper insertion slot into the printer. The paper feed roller 21 has a D-shaped cross section, and the length of the circumferential portion is set to be longer than the transport distance to the transport roller 23. 23 can be conveyed. The transport motor 22 is a motor for transporting paper in the transport direction, and is constituted by a DC motor. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable area, and is driven by the transport motor 22. The platen 24 supports the paper S being printed. The paper discharge roller 25 is a roller for discharging the printed paper S to the outside of the printer. The paper discharge roller 25 rotates in synchronization with the transport roller 23.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31, a carriage motor 32 (also referred to as a CR motor), and a carriage guide shaft 33. The carriage 31 can reciprocate in the moving direction. (Thus, the head moves along the moving direction.) The carriage 31 detachably holds an ink cartridge that stores ink. The carriage motor 32 is a motor for moving the carriage 31 in the movement direction, and is constituted by a DC motor. The carriage guide shaft 33 is a shaft for guiding the carriage 31 in the movement direction and supporting the carriage 31.

  The head unit 40 is for ejecting ink onto paper. The head unit 40 has a head 41. The head 41 has a plurality of nozzles that are ink discharge portions, and discharges ink intermittently from each nozzle. The head 41 is provided on the carriage 31. Therefore, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper.

  The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and the like. The linear encoder 51 is for detecting the position of the carriage 31 in the moving direction. The rotary encoder 52 is for detecting the rotation amount of the transport roller 23. The paper detection sensor 53 is for detecting the position of the leading edge of the paper to be printed. The paper detection sensor 53 is provided at a position where the position of the leading edge of the paper can be detected while the paper feed roller 21 feeds the paper toward the transport roller 23. The paper detection sensor 53 is a mechanical sensor that detects the leading edge of the paper by a mechanical mechanism. More specifically, the paper detection sensor 53 has a lever that can rotate in the transport direction, and this lever is disposed so as to protrude into the paper transport path. For this reason, since the leading edge of the paper comes into contact with the lever and the lever is rotated, the paper detection sensor 53 detects the position of the leading edge of the paper by detecting the movement of the lever. The optical sensor 54 is attached to the carriage 31. The optical sensor 54 detects the presence or absence of paper by the light receiving unit detecting reflected light of light irradiated on the paper from the light emitting unit. The optical sensor 54 detects the position of the edge of the paper while being moved by the carriage 41. Since the optical sensor 54 optically detects the edge of the paper, the detection accuracy is higher than that of the mechanical paper detection sensor 53. The optical sensor can detect not only the edge of the paper but also the distance between the head and the paper.

  The controller 60 is a control unit (control means) for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing the program of the CPU 62, a work area, and the like, and has storage means such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

  The PG adjustment mechanism 70 will be described in detail later.

<About printing operation>
FIG. 6 is a flowchart of processing during printing. Each process described below is executed by the controller 60 controlling each unit in accordance with a program stored in the memory 63. This program has a code for executing each process.

  The controller 60 receives a print command from the computer 110 via the interface unit 61 (S001). This print command is included in the header of print data transmitted from the computer 110. Then, the controller 60 analyzes the contents of various commands included in the received print data, and performs the following paper feed processing, transport processing, ink ejection processing, and the like using each unit.

  First, the controller 60 performs a paper feed process (S002). The paper feed process is a process of supplying paper to be printed into the printer and positioning the paper at a print start position (also referred to as a cue position). The controller 60 rotates the paper feed roller 21 and sends the paper to be printed to the transport roller 23. The controller 60 rotates the transport roller 23 to position the paper fed from the paper feed roller 21 at the print start position. When the paper is positioned at the print start position, at least some of the nozzles of the head 41 are opposed to the paper.

  Next, the controller 60 performs dot formation processing (S003). The dot forming process is a process of forming dots on paper by intermittently ejecting ink from a head that moves in the moving direction. The controller 60 drives the carriage motor 32 to move the carriage 31 in the movement direction. Then, the controller 60 ejects ink from the head based on the print data while the carriage 31 is moving. When ink droplets ejected from the head land on the paper, dots are formed on the paper.

  Next, the controller 60 performs a conveyance process (S004). The conveyance process is a process of moving the paper relative to the head along the conveyance direction. The controller 60 drives the carry motor and rotates the carry roller to carry the paper in the carrying direction. By this carrying process, the head 41 can form dots at positions different from the positions of the dots formed by the previous dot formation process.

  Next, the controller 60 determines whether or not to discharge the paper being printed (S005). If there is still data to be printed on the paper being printed, no paper is discharged. Then, the controller 60 alternately repeats the dot formation process and the conveyance process until there is no data to be printed, and gradually prints an image composed of dots on paper. When there is no more data for printing on the paper being printed, the controller 60 discharges the paper. The controller 60 discharges the printed paper to the outside by rotating the paper discharge roller. The determination of whether or not to discharge paper may be based on a paper discharge command included in the print data.

  Next, the controller 60 determines whether or not to continue printing (S006). If printing is to be performed on the next paper, printing is continued and the paper feeding process for the next paper is started. If printing is not performed on the next paper, the printing operation is terminated.

<About nozzle>
FIG. 7 is an explanatory diagram showing the arrangement of nozzles on the lower surface of the head 41. On the lower surface of the head 41, a black ink nozzle group K, a cyan ink nozzle group C, a magenta ink nozzle group M, and a yellow ink nozzle group Y are formed. Each nozzle group includes a plurality of nozzles (180 in this embodiment) that are ejection openings for ejecting ink of each color.
The plurality of nozzles of each nozzle group are aligned at a constant interval (nozzle pitch: k · D) along the transport direction. Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720), k = 4.

  The nozzles in each nozzle group are assigned a lower number in the downstream nozzle (# 1 to # 180). That is, the nozzle # 1 is located downstream of the nozzle # 180 in the transport direction. Each nozzle is provided with a piezo element (not shown) as a drive element for driving each nozzle to eject ink droplets. Further, the optical sensor 54 is substantially at the same position as the nozzle # 180 on the most upstream side with respect to the position in the paper transport direction.

=== Printing method ===
The printer can print on paper by the “interlace method” and “overlap method” described below.

<Interlace method 1>
First, an interlaced printing method will be described. Here, the “interlace method” means a printing method in which raster lines that are not recorded are sandwiched between raster lines that are recorded in one pass. The “pass” refers to an operation (dot formation operation) in which the nozzle moves once in the movement direction. A “raster line” is a row of pixels lined up in the movement direction, and is also called a scanning line. “Pixel” refers to a minimum unit constituting an image. Further, the “pixel” is a square grid which is virtually defined on the paper in order to define the position where the ink droplet is landed and the dot is recorded.

8A and 8B are explanatory diagrams of the interlace method. For convenience of explanation, the head (or nozzle group) is depicted as moving with respect to the paper, but this figure shows the relative position of the head and the paper. The paper is moved in the transport direction. In addition, the number of nozzles arranged in the transport direction is originally 180, but for the sake of simplicity, the number of nozzles is 10 here. Further, although the head has a plurality of nozzle groups, in order to simplify the description, one nozzle group of the head will be described here.
In the figure, nozzles indicated by black circles are nozzles that can eject ink, and nozzles indicated by white circles are nozzles that cannot eject ink. FIG. 8A shows the position of the head and the state of dot formation in pass 1 to pass 4, and FIG. 8B shows the position of the head and the state of dot formation in pass 1 to pass 6.

  In this interlace method, each time a sheet is conveyed by a certain conveyance amount F in the conveyance direction, each nozzle records a raster line adjacent to the raster line recorded in the immediately preceding pass. In order to perform recording with a constant carry amount in this way, the number N (integer) of nozzles that can eject ink is relatively prime to k, and the carry amount F is set to N · D.

  In the figure, the head has ten nozzles arranged along the transport direction. However, since the nozzle pitch k is 4, not all nozzles can be used in order to satisfy the condition for performing the interlace method, “N and k are relatively prime”. Therefore, the interlace method is performed using nine of the ten nozzles. In addition, since nine nozzles are used, the paper is carried by a carry amount of 9 · D. As a result, for example, using a nozzle group having a nozzle pitch of 180 dpi (4 · D), dots are formed on the paper at a dot interval of 720 dpi (= D).

  In the drawing, the first raster line is formed by nozzle # 7 in pass 1, the second raster line is formed by nozzle # 5 in pass 2, and the third raster line is formed by nozzle # 3 in pass 3. The fourth raster line is formed by nozzle # 1 in pass 4 and a continuous raster line is formed. In pass 4 and thereafter, nine nozzles (# 1 to # 9) eject ink, the paper is conveyed by a constant conveyance amount F (= 9 · D), and a continuous raster line is a dot. It is formed at an interval D.

  In the above description, the number of nozzles is ten in order to simplify the description. However, the actual number of nozzles is 180. However, since the nozzle pitch k is 4, it is not possible to use all the nozzles in order to satisfy the condition for performing the interlace method, “N and k are relatively prime”. Therefore, the interlace method is performed using 179 nozzles out of 180 nozzles. In addition, since 179 nozzles are used, the paper is carried by a carry amount of 179 · D.

<About the overlap method 1>
FIG. 9 is an explanatory diagram of the overlap method when the number of nozzles is ten. In the interlace method described above, one raster line is formed by one nozzle. On the other hand, in the overlap method, for example, one raster line is formed by two or more nozzles.

In the overlap method, each time the paper is transported at a constant transport amount F in the transport direction, each nozzle intermittently forms a dot every several dots. Then, in another pass, dots are formed so as to complement intermittent dots already formed by other nozzles, thereby completing one raster line with a plurality of nozzles. When one raster line is completed in M passes in this way, it is defined as the overlap number M. In the figure, since each nozzle intermittently forms dots every other dot, dots are formed in odd-numbered pixels or even-numbered pixels for each pass. Since one raster line is formed by two nozzles, the overlap number M = 2. In the case of the above-described interlace method, the overlap number M = 1.
In the overlap method, in order to perform recording with a constant conveyance amount, (1) N / M is an integer, (2) N / M is relatively prime to k, (3) The condition is that the carry amount F is set to (N / M) · D.

  In the figure, the nozzle group has ten nozzles arranged along the transport direction. If all 10 nozzles are used, the nozzle pitch k of the nozzle group is 4, which satisfies the condition for performing the overlap method, “N / M and k are relatively prime”. Therefore, the overlap method is performed using all ten nozzles. Further, since ten nozzles are used, the paper is transported at a transport amount of 5 · D. As a result, for example, using a nozzle group having a nozzle pitch of 180 dpi (4 · D), dots are formed on the paper at a dot interval of 720 dpi (= D). Further, in one pass, each nozzle intermittently forms dots every other dot in the movement direction. In the figure, the raster line in which two dots are drawn in the moving direction has already been completed. For example, in FIG. 9, the first raster line to the eighth raster line have already been completed. A raster line in which one dot is drawn is a raster line in which dots are intermittently formed every other dot. For example, in the ninth and thirteenth raster lines, dots are intermittently formed every other dot. The ninth raster line in which dots are intermittently formed every other dot is completed by forming dots so that nozzle # 1 in pass 9 is complemented.

In pass 8 and thereafter, ten nozzles (# 1 to # 10) eject ink, the paper is conveyed by a constant conveyance amount F (= 5 · D), and a continuous raster line is a dot. It is formed at an interval D.
In the above description, the number of nozzles is ten in order to simplify the description. However, the actual number of nozzles is 180. However, since the nozzle pitch k is 4, it is not possible to use all the nozzles in order to satisfy the condition for performing the interlace method, “N and k are relatively prime”. Therefore, the overlap method is performed using 178 nozzles out of 180 nozzles. In addition, since 178 nozzles are used, the paper is carried by a carry amount of 89 · D.

  In the overlap method, one raster line is formed by a plurality of nozzles. Therefore, even if there is a factor that degrades the image quality of the print image, the image quality degradation is reduced. For example, when there is an abnormality in the ejection amount / ejection direction of ink from a certain nozzle, in the interlace method, the raster line formed in the nozzle is formed in an abnormal state. On the other hand, in the overlap method, since other nozzles complement the dots, it is possible to mitigate the formation of raster lines in an abnormal state. It should be noted that the factor that deteriorates the image quality of the printed image is not limited to nozzle ejection abnormality. For example, a change in the transport amount and a change in the distance between the head and the paper can be a factor that degrades the image quality of the print image.

<About changing the printing method>
In the present embodiment, the printing method can be changed from the interlace method to the overlap method during printing on paper.

  FIG. 10 is an explanatory diagram showing how the printing method is changed when the number of nozzles is ten. With respect to the position of the head, the first pass shown in the figure is the Nth pass (N pass). In this case, the paper is being conveyed by the interlaced conveyance amount F = 9 · D from pass N to pass N + 5. Further, in pass N + 6 and thereafter, the paper is transported by the overlap transport amount F = 5 · D. That is, between the pass N + 5 and the pass N + 6, a change is made from the interlace transport amount to the overlap transport amount.

  In this embodiment, since the printing method is changed from the interlace method to the overlap method, the paper has a region where dots are formed by the interlace method and a region where dots are formed by the overlap method. . Further, there is a transition region in the middle of these regions where a raster line formed by one nozzle and a raster line formed by two nozzles coexist.

  In the figure, nozzles indicated by black circles are nozzles that can eject ink, and nozzles indicated by white circles are nozzles that cannot eject ink. Further, the hatched nozzle is a nozzle that ejects ink in a state different from a normal interlace method or an overlap method. For example, in the interlace method, the nozzle # 10 does not eject ink, but in the pass N + 2 to pass N + 5, the nozzle # 10 ejects ink and forms dots in the transition region. In the interlace method, one nozzle completes a raster line, but the nozzle # 9 in pass N + 2 and the nozzle # 8 and nozzle # 9 in pass N + 3 form dots intermittently every other dot. In the overlap method, each nozzle forms dots intermittently every other dot, but nozzles # 3 and # 4 in pass N + 6 eject ink so that a single nozzle forms a raster line. Then, dots are formed in the transition area.

In the present embodiment, dots are formed by a normal interlace method before pass N + 1. Further, after pass N + 9, dots are formed by the normal overlap method.
In the present embodiment, the carry amount is changed between the pass N + 5 and the pass N + 6, but the printing method change process (migration process) is performed from the pass N + 2 to the pass N + 8. As the printing method transition processing, for example, ink is ejected from the nozzle # 10 in pass N + 2, or nozzle # 5 is ejected in the manner of the interlace method in pass N + 8.

=== Detection of Head-Paper Distance ===
<PG detection sensor 1>
FIG. 11 is an explanatory diagram of the optical sensor 54 that detects the distance PG from the head to the paper. In the present embodiment, the optical sensor 54 detects not only the edge of the paper but also the distance PG from the head to the paper.
In the figure, the optical sensor 54 includes a light emitting unit 541 and two light receiving units (a first light receiving unit 542 and a second light receiving unit 543). The light emitting unit 541 includes a light emitting diode, and irradiates light onto the paper S that is a printing medium. The first light receiving unit 542 includes a light receiving element that outputs an electrical signal corresponding to the amount of light received. The second light receiving unit 543 has the same light receiving element as the first light receiving unit 542. The second light receiving unit 543 is provided at a position farther from the light emitting unit 541 than the first light receiving unit 542.

The light emitted from the light emitting unit 541 enters the paper S. The light incident on the paper S is reflected by the paper. The light reflected by the paper S enters the light receiving element. The light incident on the light receiving element is converted into an electrical signal corresponding to the amount of incident light by the light receiving element.
When the distance PG from the nozzle to the paper is small, the light reflected by the paper S1 mainly enters the first light receiving unit 542 and only the diffused light enters the second light receiving unit 543. Therefore, the output signal of the first light receiving unit 542 is larger than the output signal of the second light receiving unit 543.
On the other hand, when the distance PG from the nozzle to the paper is large, the light reflected by the paper S <b> 2 mainly enters the second light receiving unit 543, and only the diffused light enters the first light receiving unit 542. Therefore, the output signal of the second light receiving unit 543 is larger than the output signal of the first light receiving unit 542.
Therefore, if the relationship between the ratio of the output signal of the light receiving unit and the distance PG is obtained in advance, the distance PG from the nozzle to the paper can be detected based on the ratio of the output signal of the light receiving unit. In this case, information regarding the relationship between the ratio of the output signals of the light receiving unit and the distance PG may be stored in the memory 63 as a table.

<PG detection sensor 2>
The sensor is provided on the carriage. However, the sensor for detecting the distance from the head to the paper need not be provided in the carriage. A sensor may be provided on the platen that supports the paper.
FIG. 12 is an explanatory diagram of another example of detecting the distance PG from the head to the paper. In this example, the sensor 56 is provided on the platen 24. The sensor 56 detects the distance from the sensor 56 to the paper S. Since the distance from the sensor 56 to the head 41 is determined by design, if the distance from the sensor 56 to the paper S can be detected, the distance from the head 41 to the paper S can be detected.

The sensor 56 is provided at a position where ink ejected from the head does not land. For example, a groove on which ink is landed during borderless printing is provided in the platen 24 (not shown), but the sensor 56 is not provided in such a groove.
Unlike the optical sensor 54 described above, the sensor 56 is fixed and cannot move. Therefore, although the optical sensor 54 described above can detect the distance PG at various positions, the sensor 56 can detect the distance PG only at one location. However, since the sensor 56 does not need to be moved by the carriage, wiring to the carriage is reduced.
In the present embodiment described below, this sensor 56 is not employed, and the distance PG from the head 41 to the paper is detected using the optical sensor 54 described above.

=== PG adjusting mechanism ===
13 to 16 are explanatory diagrams of a PG adjustment mechanism that adjusts the distance PG from the head 41 to the paper. FIG. 13 is a perspective view of the periphery of the drive transmission unit. FIG. 14 is a side view showing the meshing state of the gear of the drive transmission unit. FIG. 15 is a perspective view of a mechanism for moving the carriage guide shaft up and down. FIG. 16 is a front view of the structure around the PG adjustment cam.

  The PG adjustment mechanism is provided in the printer, and adjusts the distance between the head and the paper by moving the carriage guide shaft 33 up and down. The PG adjustment mechanism 70 includes a motor 71, a drive transmission unit 72, a guide shaft gear 73, a PG adjustment cam 74, a fixing pin 75, and a guide groove 76.

The motor 71 generates a driving force necessary for adjusting the distance between the head and the paper. The driving force of the motor 71 is supplied to the drive transmission unit 72. The drive transmission unit 72 has a plurality of gears. The drive transmission unit 72 transmits a driving force to the guide shaft gear 73. A carriage guide shaft 33 is rotatably supported at the center of the guide shaft gear 73. A PG adjustment cam 74 is fixed to the guide shaft gear 73. Therefore, when the guide shaft gear 73 is rotated by the driving force from the drive transmission unit 72, the PG adjustment cam 74 is rotated together. However, since the carriage guide shaft 33 is freely rotatable with the guide shaft gear 73, the carriage guide shaft 33 does not rotate. The outer peripheral surface of the PG adjustment cam 74 is in contact with the fixing pin 75. The fixing pin 75 functions as a cam follower for the PG adjustment cam 74. The guide groove 76 guides the carriage guide shaft 33 in the vertical direction. For this reason, even if the carriage guide shaft 33 receives a force from the outside, the movement in the horizontal direction is restricted.
When the motor 71 is driven, the guide shaft gear 73 is rotated via the drive transmission unit 72. When the guide shaft gear rotates, the PG adjustment cam 74 rotates, and a force is applied to the carriage guide shaft 33 by the action of the outer peripheral surface of the PG adjustment cam 74 and the fixing pin 75. The carriage guide shaft 33 is guided in the guide groove and moves in the vertical direction. As a result of the carriage guide shaft 33 moving up and down, the carriage 31 supported by the carriage guide shaft 33 also moves up and down. Thereby, the distance PG between the head 41 and the paper is adjusted.
When the controller 60 gives a drive instruction to the PG adjustment mechanism, the motor 71 is driven according to the drive instruction, and the distance PG between the head 41 and the paper is adjusted.

=== Change timing ===
<About the process flow>
17 to 19 are flowcharts of processing performed in the present embodiment. These processes are realized by the controller 60 controlling each unit according to a program. This program is made up of program codes for performing each process, and is stored in the memory 63 in the printer.

  Each process shown in FIG. 17 is performed during any one of S003 to S005 in FIG. For example, each process shown in FIG. 17 is performed immediately before or immediately after the dot formation process (S003) in S003 or immediately after the transport process (S004). Since the processes of S003 to S005 are repeatedly performed until YES is determined in S005, the processes shown in FIG. 17 are also repeatedly performed.

  First, the optical sensor 54 detects the distance PG from the head to the paper (S101). The detected distance PG is stored in the memory 63. Next, a printing method determination process or a PG adjustment process is performed based on the detected distance PG (S102). In the present embodiment, first, a printing method determination process is performed.

  FIG. 18 is a flowchart of the printing method determination process. First, the controller 60 compares the detected distance PG with a preset threshold value PG1 (S201). If the detected distance PG is larger than the threshold value PG1 (YES in S201), the distance between the head 41 and the paper is sufficient, and the interlace method is determined as the printing method (S202). For this reason, in the next dot formation process (S003), printing is performed by the interlace method.

On the other hand, if the detected distance PG is smaller than the threshold value PG1 (NO in S201), the distance between the head 41 and the paper has become narrower. Therefore, in order to switch the printing method to the overlap method, the printing method transition processing is performed. Start (S203). Specifically, in the first dot formation processing after the printing method transition processing is started, the head ejects ink from the nozzles as in pass N + 2 in FIG. 10 (in spite of the interlace method, nozzle # 10 From the ink). Then, after a plurality of dot formation processes, the process completely shifts to overlap printing as shown in pass N + 9 in FIG.
After starting the printing method change process, the controller 60 performs setting so that the PG adjustment process is performed in S102 after the PG detection in S101 of FIG. 17 (S204). Thereby, after starting the printing method change process once, the PG adjustment process is performed in S102 of FIG.

FIG. 19 is a flowchart of the PG adjustment process. First, the controller 60 compares the detected distance PG with a preset threshold value PG2 (S301). When this threshold value PG2 is compared with the aforementioned threshold value PG1, PG2 is a smaller value. The threshold values PG1 and PG2 will be described later in detail.
If the detected distance PG is larger than the threshold value PG2 (YES in S301), the distance between the head 41 and the paper is sufficient, and the current distance PG is maintained without driving the PG adjustment mechanism (S302).
On the other hand, if the detected distance PG is smaller than the threshold value PG2 (NO in S301), there is a possibility that the head 41 and the paper come into contact with each other, so the controller 60 drives the PG adjustment mechanism and the distance between the head 41 and the paper. To spread.

  In the present embodiment, the printing method is switched from the interlace method to the overlap method based on the detection result of the optical sensor 54. Therefore, in the present embodiment, when the distance PG detected by the optical sensor 54 exceeds the threshold PG1, the printer transmits a signal indicating that to the printer driver. After receiving the signal, the printer driver performs rasterization processing so as to shift from the interlace method to the overlap method, and rearranges the matrix pixel data. The printer driver transmits print data including the rearranged pixel data to the printer, and the printer ejects ink from each nozzle based on the print data. As a result, as shown in FIG. 10, in each pass, ink is ejected from each nozzle, and the printing method is switched from the interlace method to the overlap method.

<About threshold>
20A and 20B are explanatory diagrams illustrating the relationship between the threshold PG1 and the threshold PG2.
Usually, the paper S is transported by two rollers, a transport roller 23 and a paper discharge roller 25. In this case, since the paper is supported by the rollers on both sides of the print area, the paper is in a tensioned state in the print area. The threshold value PG1 is set to a smaller value than the distance between the head 41 and the paper S at this time. Therefore, while the paper is being transported by the transport roller 23 and the paper discharge roller 25, the determination in S201 of FIG. 18 is YES, and interlaced printing is performed. While the paper is being transported by the transport roller 23 and the paper discharge roller 25, the distance between the head 41 and the paper S is constant over the entire printing area. Therefore, there are few factors that cause the print image to deteriorate, and even with the interlace method, the print image can be printed on paper with good image quality.

  When the conveyance process is repeated, the trailing edge of the paper passes through the conveyance roller 23. When the trailing edge of the paper S passes the transport roller 23, the paper S is cantilevered by the paper discharge roller 25. At this time, if the paper is warped, the surface of the paper is lifted from the platen 24 and the distance between the head 41 and the paper S is reduced. Further, as shown in FIG. 20B, the rear end of the paper approaches the head 41. For this reason, if the carrying process is repeated, the paper gradually approaches the head 41.

When the trailing edge of the paper S passes the transport roller 23, the distance between the head 41 and the paper S may be different depending on the location of the printing area. If the distance between the head 41 and the paper S is different, the print image is deteriorated. For this reason, it is desirable to perform overlap printing in a place where the paper S is greatly lifted from the platen 24.
Therefore, in this embodiment, if the distance PG detected by the optical sensor is smaller than the threshold value PG1, the printing method change process is started in order to switch the printing method to the overlap method (NO in S201, S203). .

  However, the image quality of the interlaced print image and the image quality of the overlapped print image are different.

FIG. 21 is a diagram for explaining the deterioration of the image quality of the entire print image. In the paper S in the figure, the hatched portion indicates a print image printed on the paper. The upper side of the print image is an interlaced print area. The lower side of the print image is an overlap print area. For example, even if the density of both print areas is the same (in this explanatory diagram, the density of hatching lines is the same), as shown in FIG. The image quality of the entire printed image will deteriorate.
Therefore, when the printing method is changed from the interlace method to the overlap method, the image quality of the entire print image is somewhat deteriorated at the boundary portion between the interlace print region and the overlap print region.

Similarly, when the distance between the head 41 and the paper is adjusted by driving the PG adjusting mechanism, the distance between the head 41 and the paper is different before and after the adjustment. For this reason, image quality modulation is conspicuous at the boundary between the print area printed before the adjustment by the PG adjustment mechanism and the print area printed after the adjustment, and the entire print image deteriorates somewhat (in this case, the print image The deterioration is also almost the same as in FIG.
If the modulation portion of the image quality due to the printing method change coincides with the modulation portion of the image quality due to the PG adjustment, the modulation of the image quality between the two print areas becomes large. Then, since the change in image quality becomes large at the boundary between the two print areas shown in FIG. 21, the deterioration of the image quality of the entire print image becomes very conspicuous.

  Therefore, in this embodiment, the timing at which the printing method is changed and the timing at which the PG adjustment mechanism is driven are shifted. Specifically, since the interlace transport amount is switched to the overlap transport amount between the paths N + 5 and N + 6 in FIG. 10, the PG adjustment mechanism is not driven between the paths N + 5 and N + 6. Like that. Thereby, the modulation part of the image quality due to the change of the printing method and the modulation part of the image quality due to the PG adjustment do not coincide with each other, and the change in the image quality in the modulation part becomes small.

  In this embodiment, the drive timing of the PG adjustment mechanism is after the path N + 6. In order to drive the PG adjusting mechanism at such a timing, the width L shown in FIG. 20B is set so that the conveyance amount between pass N + 1 and pass N + 6 shown in FIG. 10 (from the position of nozzle # 10 in pass N + 1). (Distance to the position of nozzle # 10 in pass N + 6). In other words, the threshold value PG1 and the threshold value PG2 are set so that the width L shown in FIG. 20B has such a length. In this case, the reference pass N + 1 is a “pass immediately before the transition process is started (dot formation process)”. Further, the reference path N + 6 in this case is “pass immediately after the transport amount is changed to the overlap-type transport amount”.

  In FIG. 20B, when the paper S is transported in the transport direction and the position A of the paper S has passed the detection area of the optical sensor 54 (already passed in FIG. 20B), the distance detected by the optical sensor 54. PG becomes smaller than the threshold value PG1. Further, when the position B of the paper S passes the detection area of the optical sensor 54 (not yet passed in FIG. 20B), the distance PG detected by the optical sensor 54 becomes smaller than the threshold PG2.

Furthermore, it is not desirable that the drive timing of the PG adjustment mechanism be before the path N + 5 in FIG. In this case, the reference path N + 5 is “the last path based on the interlaced transport amount”. Even if interlaced transport is performed, ink is irregularly ejected from the nozzles during pass N + 2 and before pass N + 5 (for example, irregularly ink is ejected from the hatched nozzles in FIG. 10). Therefore, the image quality of the print image formed at this time is modulated with the image quality of the surrounding print image. Therefore, if the drive timing of the PG adjustment mechanism is before the path N + 5, the image quality modulation part by the printing method transition process overlaps with the image quality modulation part by the PG adjustment, and the image quality of the entire print image is greatly deteriorated. End up.
If the width L shown in FIG. 20B is longer than the transport amount between pass N + 1 and pass N + 6 shown in FIG. 10, it is possible to avoid driving the PG adjusting mechanism before pass N + 5. .

Furthermore, it is desirable that the drive timing of the PG adjustment mechanism be after the path N + 8 in FIG. In this case, the reference path N + 8 is a “pass where the printing method transition process ends”. Since the ink is irregularly ejected from the nozzle before the end of the printing method transition process (for example, the ink is irregularly ejected from the hatched nozzle in FIG. 10), the printing formed at this time The image quality is modulated with the image quality of the surrounding print image. Therefore, if the drive timing of the PG adjustment mechanism is after the path N + 8, the image quality modulation part by the printing method transition process and the image quality modulation part by the PG adjustment do not overlap, and the image quality of the entire print image is deteriorated. Can be further suppressed.
In order to drive the PG adjustment mechanism at such timing, the width L shown in FIG. 20B needs to be longer than the transport amount from pass N + 1 to pass N + 8.

Furthermore, it is desirable that the drive timing of the PG adjustment mechanism be after the path N + 11 in FIG. In this case, the reference pass N + 11 is “the last pass for forming dots in the transition region”. In the transition area shown in FIG. 10, a raster line formed by one nozzle and a raster line formed by two nozzles are mixed. For this reason, this region is a boundary between the interlaced print region and the overlap print region, and is also a portion where image quality modulation is conspicuous. Therefore, if the drive timing of the PG adjustment mechanism is after the path N + 11, the transition area and the modulation part of the image quality by the PG adjustment do not overlap, and the deterioration of the image quality of the entire print image can be further suppressed.
In order to drive the PG adjustment mechanism at such timing, the width L shown in FIG. 20B needs to be longer than the transport amount from pass N + 1 to pass N + 11.

By the way, there are a plurality of factors as the reason why the paper warps. First, as a first reason, it is conceivable that the paper warps due to the force received by the paper during conveyance. The second reason is that the paper absorbs ink during printing, the paper becomes wet, and there is a difference in expansion and contraction between the printed part and the non-printed part. It is possible to end up. For any reason, the amount of deformation differs depending on the type of paper. In other words, if the paper types are the same, the way of warping the paper is almost the same.
Therefore, even if the threshold value PG1 and the threshold value PG2 are the same, the length of the width L in FIG. 20B differs depending on the type of paper. In other words, the threshold values PG1 and PG2 are set according to the type of paper so that FIG. 20B has a desired length.

=== Other Embodiments ===
The above-described embodiment is mainly described for a printer. Among them, a printing apparatus, a recording apparatus, a liquid ejection apparatus, a printing method, a recording method, a liquid ejection method, a printing system, a recording system, and a computer system are included. Needless to say, the disclosure includes a program, a storage medium storing the program, a display screen, a screen display method, a printed material manufacturing method, and the like.

  Moreover, although the printer etc. as one embodiment were demonstrated, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About threshold value PG1>
According to the above-described embodiment, when the distance PG detected by the optical sensor 54 is smaller than the predetermined threshold PG1, the printing method is changed. However, the timing for changing the printing method is not limited to this.

For example, the printing method may be changed based on the history of detection results of the optical sensor 54. For example, based on the detection result history of the optical sensor 54, it is predicted how many transport operations the distance PG between the head and the paper will be equal to or less than the threshold PG2, and the printing method is changed based on the prediction result You may do it. Specifically, the angle of paper warp is calculated based on the detection result of the distance PG twice before and after the transport operation, and the distance between the head and the paper becomes equal to or less than the threshold PG2 based on the calculated angle. Predicts how many times the transfer operation will be performed. This will be described with reference to FIG. When it is predicted that the distance PG is equal to or less than the threshold value PG2 in pass N + 1 after the N-th transport operation, if the printing method transition process is started when N> 4, the drive timing of the PG adjustment mechanism Is after path N + 6.
In this case, since the inclination (warp) of the paper is detected by the optical sensor, it is not necessary to set the threshold value PG1 and the threshold value PG2 for each paper type.

<About the number of nozzles>
In the above-described embodiment, the number of nozzles is ten. However, the number of nozzles is not limited to this. Actually, as described above, the number of nozzles is 180, but it is not limited to this number.

<About the printing method>
In the above-described embodiment, the printing method is switched from the interlace method to the overlap method. However, the printing method is not limited to this.

For example, the printing method may be switched from a two-pass overlap method in which one raster line is formed by two nozzles to a four-pass overlap method in which one raster line is formed by four nozzles.
However, the printing method after switching has a larger number of nozzles for forming one raster line than the printing method before switching. This is because, when the number of nozzles forming one raster line is large, even if there is a factor that degrades the image quality (for example, variation in the distance PG), the degradation of the image quality due to the factor can be reduced. .
As the number of nozzles forming one raster line increases (the overlap number M increases), the transport amount (F = (N / M) · D) in the transport operation of the printing method decreases.

<About the number of times the printing method is switched>
In the above-described embodiment, the printing method is changed first, and then the PG adjustment mechanism is driven to adjust the distance PG. That is, in the above-described embodiment, the printing method is changed and the distance PG is adjusted only once. However, it is not limited to this.
For example, a large number of threshold values may be set, and the printing method change and the distance PG adjustment may be performed a plurality of times while the printing method change timing and the distance PG adjustment timing do not match.

<About the top edge of the paper>
In the above-described embodiment, the printing method is changed at the trailing edge of the paper. However, changing the printing method is not limited to the trailing edge of the paper. When printing the upper end of the paper, the printing method may be changed. However, when printing the upper end of the paper, the paper S is cantilevered by the transport roller 23, contrary to FIG. 20B, until the upper end of the paper passes the paper discharge roller 25. For this reason, in the above-described embodiment, the PG adjustment processing is performed after the printing method determination processing in S102. However, the processing may be performed in the reverse order.

<About rasterization processing>
According to the above-described embodiment, the rasterizing process is performed by the printer driver outside the printer. However, the rasterization process need not be performed outside the printer. For example, rasterization processing may be performed in the printer apparatus. In this case, it is not necessary to transmit the detection result of the optical sensor 54 (a signal indicating that the detected distance PG is smaller than the threshold value PG1) to the outside of the printer.

<About ink>
Since the above-described embodiment is an embodiment of a printer, dye ink or pigment ink is ejected from the nozzle. However, the liquid ejected from the nozzle is not limited to such ink. For example, liquids (including water) including metal materials, organic materials (especially polymer materials), magnetic materials, conductive materials, wiring materials, film-forming materials, electronic inks, processing liquids, gene solutions, etc. are ejected from nozzles. May be. If such a liquid is directly discharged toward the object, material saving, process saving, and cost reduction can be achieved.

<About nozzle>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

=== Summary ===
(1) The printer (printing apparatus) of the above-described embodiment includes a head (ink ejection unit) that ejects ink onto paper (medium), and ejects ink from the head to form dots on the paper. In such a printer, a gap is provided between the head and the paper so that the head can move relative to the paper. Then, the ink ejected from the head flies through this gap and land on the paper, forming dots on the paper.
However, in such a printer, a change in the interval between the paper and the head becomes a cause of deterioration in the image quality of the printed image. In other words, when the distance between the paper and the head changes, the ink landing position shifts, and the image quality of the printed image deteriorates.
On the other hand, in the printing method in which one raster line is formed by a plurality of nozzles, such as the overlap method, it is possible to reduce such deterioration of the image quality of the printed image.
Therefore, the printer (printing apparatus) of the above-described embodiment can detect a change in the distance between the carriage (moving body) that moves the head (ink ejection unit) that ejects ink onto the paper (medium) and the paper and the head. An optical sensor and ejects ink from a head by a plurality of printing methods to form dots on paper, and the printing method is switched based on the detection result of the optical sensor.
Thus, even when the interval between the paper and the head changes and the image quality of the printed image deteriorates, the deterioration of the image quality can be alleviated by switching the printing method.

(2) In the printer of the above-described embodiment, the optical sensor 54 is movable together with the carriage (moving body). Thereby, the optical sensor 54 can detect the space | interval of paper and a head not only in one place but in several places.

(3) In the printer of the above-described embodiment, the head (ink ejection unit) has a plurality of nozzles arranged along the transport direction, and the optical sensor is from nozzle # 1 (the nozzle on the most downstream side in the transport direction). Is also provided upstream in the transport direction.
Assuming that the optical sensor is provided on the downstream side of the nozzle # 1, when the optical sensor detects that the distance PG between the head and the paper is smaller than the threshold PG2, the trailing edge of the paper is already at the head. There is a risk of touching. Therefore, in the above-described printer, an optical sensor is provided upstream of the nozzle # 1 in the transport direction in order to prevent the rear end of the paper from coming into contact with the head.

(4) However, the sensor that detects the change in the interval between the paper and the head does not need to be movable together with the carriage. As shown in FIG. 12, the sensor may be provided on a platen that supports paper. In this case, wiring for the carriage is reduced.

(5) In the printer of the above-described embodiment, the head has a plurality of nozzles, and the number of nozzles used when forming one raster line is different in a plurality of printing methods. For example, in the interlace method, one raster line is formed by one nozzle, but in the overlap method, one raster line is formed by two nozzles. In this way, if the number of nozzles used in forming one raster line is different, the degree of deterioration of the image quality of the printed image will be different when the interval between the paper and the head is changed. If such a printing method is switched based on the detection result of the sensor, the image quality of the printed image can be improved.
Note that the present invention is not limited to switching between the interlace method and the overlap method. For example, switch between 2-pass overlap method (method using two nozzles when forming one raster line) and 4-pass overlap method (method using four nozzles when forming one raster line) May be.

(6) In the printer of the above-described embodiment, the printing method after switching has an overlap number M (the number of nozzles used when forming one raster line) than the printing method before switching. Many. For example, in the above-described embodiment, the printing method is switched from the interlace method (M = 1) to the overlap method (M = 2). By switching the printing method in this way, when the distance between the head and the paper changes, the influence can be reduced and the quality of the printed image can be improved (degradation of the quality of the printed image can be suppressed). it can).

(7) The printer of the above-described embodiment includes a PG adjustment mechanism that adjusts the distance between the paper and the head. Then, the PG adjustment mechanism is driven at a timing different from the timing of switching the printing method.
Thereby, the modulation part of the image quality due to the change of the printing method and the modulation part of the image quality due to the PG adjustment do not coincide with each other, and the change in the image quality in the modulation part becomes small.
Even if the PG adjusting mechanism is not provided, the effect of suppressing the deterioration of the image quality can be obtained by switching the printing method based on the detection result of the sensor. Even when the timing for switching the printing method coincides with the timing for driving the PG adjusting mechanism, the image quality deterioration suppressing effect corresponding to the switching of the printing method is obtained. However, in these cases, the effect obtained when the PG adjustment mechanism is driven at a timing different from the timing of switching the printing method cannot be obtained.

(8) In the printer of the above-described embodiment, a plurality of printing methods have different transport amounts for transporting paper. For example, when the number of nozzles is 10, the transport amount is 9 · D in the interlace method, and the transport amount is 5 · D in the overlap method. Further, when the number of nozzles is 180, the transport amount is 179 · D in the interlace method, and the transport amount is 89 · D in the overlap method. In the above-described embodiment, the adjustment mechanism is driven at a timing different from the timing at which the carry amount is switched.
When the carry amount changes, the image quality is modulated at the boundary portion of the print image before and after the change in the carry amount, and the image quality of the entire print image deteriorates. However, in this embodiment, the modulation part of the image quality due to the light on both sides of the conveyance and the modulation part of the image quality due to the PG adjustment do not match, and the change in the image quality in the modulation part becomes small. Can do.

(9) In the printer of the above-described embodiment, when the printing method is switched, the transition process is performed during the switching. For example, as shown in FIG. 10, when switching from the interlace method to the overlap method, the printing method transition process is started from pass N + 2, the printing method transfer process is completed by pass N + 8, and the complete overlap method is switched in pass N + 9. . In the above-described embodiment, the PG adjustment mechanism is driven after the transition process. For example, the PG adjustment mechanism is driven after pass N + 8 in FIG. As a result, the image quality modulation part by the printing method transition process and the image quality modulation part by the PG adjustment do not overlap, and deterioration of the image quality of the entire print image can be suppressed.

(10) In the printer of the above-described embodiment, an interlaced printing area (first area) printed by the interlace method (printing method before switching) and an overlap printed by the overlapping method (printing method after switching). The area where the print area (second area) is formed on the paper and the head performs printing after driving the PG adjusting mechanism is the overlap print area. For example, the area where the head performs printing after driving the PG adjustment mechanism is the overlap printing area in FIG. As a result, the image quality modulation part by the printing method transition process and the image quality modulation part by the PG adjustment do not overlap, and deterioration of the image quality of the entire print image can be suppressed.

(11) In the printer of the above-described embodiment, a transition area is formed between the interlaced printing area (first area) and the overlap printing area (second area). For example, when the boundary portion between the two print areas in FIG. 21 is enlarged, a transition area exists between the two print areas as shown in FIG. In the above-described embodiment, after the transition region is formed, the PG adjustment mechanism is driven. For example, in FIG. 10, the PG adjustment mechanism is driven after pass N + 11. As a result, the image quality modulation part by the printing method transition process and the image quality modulation part by the PG adjustment do not overlap, and deterioration of the image quality of the entire print image can be suppressed.

(12) The printer according to the above-described embodiment includes a transport roller and a paper discharge roller. When only one of the transport roller and the paper discharge roller is transporting the paper, the PG adjustment mechanism is driven. During such conveyance, the paper is in a cantilever state, the paper is lifted from the platen, and the paper may come into contact with the head. Therefore, by driving the PG adjustment mechanism, the distance between the head and the paper is adjusted to prevent the paper from coming into contact with the head.

(13) In the printer of the above-described embodiment, the threshold PG1 (first threshold) and the threshold PG2 (second threshold) are stored in the memory. When the distance PG (detection result) detected by the optical sensor exceeds the threshold PG1, the printing method is switched. When the distance PG (detection result) detected by the optical sensor exceeds the threshold PG2 (second threshold), the PG adjustment mechanism is driven.
Thereby, the PG adjustment mechanism can be driven at a timing different from the timing of switching the printing method. As a result, the modulation portion of the image quality due to the change of the printing method and the modulation portion of the image quality due to the PG adjustment do not coincide with each other, and the change in the image quality in the modulation portion becomes small.

(14) However, there is a method in which the two threshold values are not stored.
For example, only the threshold value PG2 (predetermined threshold value) is stored, the time when the detection result of the optical sensor exceeds the threshold value PG2 is predicted based on the history of the detection result of the optical sensor, and the printing method is changed based on the prediction result. You may switch. For example, the angle of the paper warp is calculated based on the detection result of the two distances PG before and after the transport operation, and the distance PG between the head and the paper after the number of transports is less than or equal to the threshold PG2 based on the calculated angle. Predict what will be. When the predicted number of conveyances reaches a predetermined number, the printing method is switched, and when the detection result of the optical sensor exceeds the threshold value PG2, the PG adjustment mechanism is driven.
Accordingly, the PG adjustment mechanism can be driven at a timing different from the timing of switching the printing method without storing the two threshold values. In addition, the switching timing of the printing method can be adjusted in accordance with the actual paper warpage.

(15) In the printer of the above-described embodiment, the head (ink ejection unit) has a plurality of nozzles, transmits the detection result of the optical sensor to the printer driver of the computer (external device), and receives print data from the computer. Ink is ejected from each nozzle based on the print data to form dots on the paper. As a result, the rasterization process is performed on the printer driver side according to the distance between the head and the paper, and the printer driver can generate print data including pixel data corresponding to the switching of the printing method.

(16) However, the rasterization process is not limited to that performed on the printer driver side.
For example, a printer performs rasterization processing to generate print data (generates print data by rearranging pixel data in a matrix form of image data in accordance with the arrangement of nozzles), and based on this print data, each nozzle Ink may be ejected from the ink to form dots on the paper. Then, the printer performs rasterization processing based on the detection result of the optical sensor to generate print data. In this case, it is not necessary to transmit the sensor detection result to the outside of the printer.

(17) According to the printer including all the above-described components, all the effects can be obtained, so that a high-quality image can be obtained.

(18) In the printing method described above, dots are formed on the paper (medium) by ejecting ink from the head (ink ejection unit) by the interlace method (first printing method), and the change in the distance between the paper and the head. And switching the printing method from the interlace method (first printing method) to the overlapping method (second printing method) based on the detection result, and ink from the head in the overlapping method (second printing method). To form dots on the paper.
Thus, even when the interval between the paper and the head changes and the image quality of the printed image deteriorates, the deterioration of the image quality can be alleviated by switching the printing method.

(19) The above-described printer driver (program) or a program stored in the memory in the printer ejects ink from the head (ink ejection unit) by a plurality of printing methods to form dots on the paper (medium). The printer (printing apparatus) realizes the function and the function of switching the printing method based on the detection result of the optical sensor.
As a result, the printing apparatus can be controlled to switch the printing method even when the interval between the paper and the head changes and the quality of the print image deteriorates. As a result, it is possible to mitigate deterioration of the image quality of the printed image.

(20) The aforementioned printing system includes a printer (printing apparatus) and a computer. The printer includes a carriage (a moving body that moves an ink ejection unit that ejects ink onto a medium) and an optical sensor that can detect a change in the interval between the paper and the head, based on the detection result of the optical sensor. Switch the printing method.
Thus, even when the interval between the paper and the head changes and the image quality of the printed image deteriorates, the deterioration of the image quality can be alleviated by switching the printing method.

It is explanatory drawing of the whole structure of a printing system. FIG. 10 is an explanatory diagram of processing performed by a printer driver. 1 is a block diagram of an overall configuration of a printer. 1 is a schematic diagram of an overall configuration of a printer. 1 is a cross-sectional view of the overall configuration of a printer. It is a flowchart of the process at the time of printing. It is explanatory drawing which shows the arrangement | sequence of a nozzle. 8A and 8B are explanatory diagrams of the interlace method. It is explanatory drawing of an overlap system. It is explanatory drawing of the mode of a printing system change in case the number of nozzles is eight. It is explanatory drawing of the optical sensor 54 which detects the distance PG from a head to paper. It is explanatory drawing of another example which detects the distance PG from a head to paper. It is a perspective view of the periphery of a drive transmission part. It is a side view which shows the meshing state of the gear of a drive transmission part. It is a perspective view of the mechanism which raises / lowers a carriage guide shaft. It is a front view of the structure around PG adjustment cam. It is a flowchart of the process performed by this embodiment. It is a flowchart of a printing system determination process. It is a flowchart of PG adjustment processing. 20A and 20B are explanatory diagrams illustrating the relationship between the threshold PG1 and the threshold PG2. It is a figure for demonstrating degradation of the image quality of the whole printed image.

Explanation of symbols

1 printer,
20 transport unit, 21 paper feed roller, 22 transport motor (PF motor),
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage,
32 Carriage motor (CR motor),
40 head units, 41 heads,
50 detector groups, 51 linear encoder, 52 rotary encoder,
53 Paper detection sensor, 54 Optical sensor,
60 controller, 61 interface unit, 62 CPU,
63 memory, 64 unit control circuit,
70 PG adjustment mechanism, 71 motor, 72 drive transmission unit, 73, guide shaft gear,
74 PG adjustment cam, 75 fixing pin, 76 guide groove,
100 printing system 110 computer,
112 video drivers, 114 application programs,
116 printer driver 120 display device;
130 input device, 130A keyboard, 130B mouse,
140 recording / reproducing apparatus,
140A flexible disk drive device,
140B CD-ROM drive device

Claims (20)

A moving body that moves an ink discharge section that discharges ink onto a medium;
A sensor capable of detecting a change in an interval between the medium and the ink ejection unit;
With
A printing apparatus that forms dots on the medium by discharging the ink from the ink discharge unit using a plurality of printing methods,
A printing apparatus that switches the printing method based on a detection result of the sensor. The printing apparatus according to claim 1,
The printing apparatus, wherein the sensor is movable with the moving body. The printing apparatus according to claim 2,
The ink ejection unit has a plurality of nozzles arranged along the transport direction,
The printing apparatus according to claim 1, wherein the sensor is provided on the upstream side in the transport direction with respect to the nozzle on the most downstream side in the transport direction. The printing apparatus according to claim 1,
The printing apparatus, wherein the sensor is provided on a platen that supports the medium. The printing apparatus according to any one of claims 1 to 4,
The ink ejection unit has a plurality of nozzles,
In the plurality of printing methods, the number of the nozzles used when forming one raster line is different from each other. The printing apparatus according to claim 5,
A printing apparatus in which the number of nozzles used in forming one raster line is greater in a printing method after switching than in a printing method before switching. The printing apparatus according to any one of claims 1 to 6,
An adjustment mechanism for adjusting a distance between the medium and the ink ejection unit;
The printing apparatus, wherein the adjustment mechanism is driven at a timing different from a timing of switching the printing method. The printing apparatus according to claim 7, wherein
The plurality of printing methods have different transport amounts for transporting the medium,
The printing apparatus, wherein the adjustment mechanism is driven at a timing different from a timing at which the carry amount is switched. The printing apparatus according to claim 7 or 8,
When switching the printing method, a transition process is performed during the switching,
The printing apparatus, wherein the adjustment mechanism is driven after the transition process. The printing apparatus according to any one of claims 7 to 9,
A first area printed by the printing method before switching and a second area printed by the printing method after switching are formed on the medium,
The printing apparatus is characterized in that a region where the ink ejection unit performs printing after driving the adjustment mechanism is the second region. The printing apparatus according to claim 10,
A transition region is formed between the first region and the second region;
A printing apparatus that drives the adjustment mechanism after the transition region is formed. It is a printing apparatus in any one of Claims 7-11, Comprising:
A conveyance roller and a discharge roller;
The printing apparatus, wherein only one of the transport roller and the paper discharge roller drives the adjustment mechanism when transporting the medium. The printing apparatus according to any one of claims 7 to 12,
Storing a first threshold and a second threshold;
When the detection result of the sensor exceeds the first threshold, the printing method is switched,
The printing apparatus, wherein the adjustment mechanism is driven when a detection result of the sensor exceeds the second threshold value. The printing apparatus according to any one of claims 7 to 12,
Memorize a predetermined threshold,
Based on the detection result history of the sensor, predict when the detection result of the sensor exceeds the predetermined threshold,
Based on the prediction result, the printing method is switched,
The printing apparatus, wherein the adjustment mechanism is driven when a detection result of the sensor exceeds the predetermined threshold value. The printing apparatus according to claim 1,
The ink ejection unit has a plurality of nozzles,
Send the detection result of the sensor to an external device,
Receiving print data from the external device;
A printing apparatus, wherein ink is ejected from each nozzle based on the print data to form dots on the medium. The printing apparatus according to claim 1,
The ink ejection unit has a plurality of nozzles,
Rearrange pixel data in matrix form of image data according to the arrangement of the nozzles to generate print data,
A printing apparatus that ejects ink from each nozzle based on the print data and forms dots on the medium,
The print data is generated based on the detection result of the sensor. A moving body that moves an ink discharge section that discharges ink onto a medium;
A sensor capable of detecting a change in an interval between the medium and the ink ejection unit;
With
A printing apparatus that forms dots on the medium by discharging the ink from the ink discharge unit using a plurality of printing methods,
Based on the detection result of the sensor, the printing method is switched,
The sensor is movable with the moving body,
The ink ejection unit has a plurality of nozzles arranged along the transport direction,
The sensor is provided on the upstream side in the transport direction with respect to the nozzle on the most downstream side in the transport direction,
In the plurality of printing methods, the number of the nozzles used when forming one raster line is different, respectively.
The number of the nozzles used when forming one raster line is larger in the printing method after switching than in the printing method before switching,
An adjustment mechanism for adjusting a distance between the medium and the ink ejection unit;
Driving the adjusting mechanism at a timing different from the timing of switching the printing method;
The plurality of printing methods have different conveyance amounts for conveying the medium, and drive the adjustment mechanism at a timing different from the timing at which the conveyance amount is switched.
When switching the printing method, a transition process is performed during the switching, and after the transition process, the adjustment mechanism is driven,
A first area printed by the printing method before switching and a second area printed by the printing method after switching are formed on the medium,
The area where the ink ejection unit performs printing after driving the adjustment mechanism is the second area,
A transition region is formed between the first region and the second region, and after the transition region is formed, the adjustment mechanism is driven,
A conveyance roller and a discharge roller;
When only one of the transport roller and the discharge roller is transporting the medium, the adjustment mechanism is driven,
Storing a first threshold and a second threshold;
When the detection result of the sensor exceeds the first threshold, the printing method is switched,
When the detection result of the sensor exceeds the second threshold value, the adjustment mechanism is driven.
Send the detection result of the sensor to an external device,
Receiving print data from the external device;
A printing apparatus, wherein ink is ejected from each nozzle based on the print data to form dots on the medium. Ink is ejected from the ink ejection unit in the first printing method to form dots on the medium,
Detecting a change in an interval between the medium and the ink ejection unit;
Based on the detection result, switching from the first printing method to the second printing method,
A printing method, comprising: ejecting ink from the ink ejection unit by the second printing method to form dots on the medium. A moving body that moves an ink discharge section that discharges ink onto a medium;
A sensor capable of detecting a change in an interval between the medium and the ink ejection unit;
In a printing device equipped with
A function of ejecting the ink from the ink ejection unit by a plurality of printing methods to form dots on the medium;
A program that realizes a function of switching the printing method based on a detection result of the sensor. A printing device and a computer;
The printing apparatus includes a moving body that moves an ink ejection unit that ejects ink onto a medium, and a sensor that can detect a change in the interval between the medium and the ink ejection unit.
A printing system that ejects the ink from the ink ejection unit in a plurality of printing methods to form dots on the medium,
A printing system, wherein the printing method is switched based on a detection result of the sensor.

Images