JP2007136946A - Printing device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image with less joined stripes between printing bands without additional storage means. <P>SOLUTION: Printing data input from a host computer 301 are divided into a plurality of bands and managed as such, and the printing data are rendered per divided band and stored into band memory 309. In addition, when it is detected by a means 313 to measure the time interval of a printing scan that the time interval of the printing scan exceeds the specified readings, the rendering results stored in the band memory 309, are printed out by a printer engine 303 through a dot data creation means, using a part of a printing head set by a printing width decision means 312. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus, and more particularly to an ink jet printing apparatus that performs recording by ejecting ink from a recording head having a plurality of ejection openings and a printing data processing method.

  Printing devices such as printers, copiers, and facsimile machines are configured to record an image having a dot pattern on a recording material based on image information. The printing device can be divided into an ink jet type, a wire dot type, a thermal type, a laser beam type, etc., depending on the printing method, and the ink jet type printing device can be used from the discharge port of the recording head. Ink (recording liquid) droplets are ejected and ejected, and are adhered to a recording material for recording.

  In general, an ink jet printing apparatus includes a carriage on which recording means (print head) and an ink tank are mounted, a transport means for transporting recording paper, and a control means for controlling them. Then, the print head that discharges ink droplets from multiple discharge ports is scanned (print scan) in the direction (main scan direction) perpendicular to the transport direction (sub-scan direction) of the recording paper, while at the same time the recording width is set when recording is not performed. Intermittent conveyance is performed with an equal amount. Furthermore, in the case of a color-compatible ink jet printing apparatus, a color image is formed by superimposing ink droplets ejected by a plurality of color print heads.

  This recording method is to record characters and figures by ejecting ink from the ejection port onto the recording medium as minute droplets according to the recording signal, and is non-impact so that there is less noise, Copiers used in combination with computers and word processors, or used alone because of the advantages such as low running cost, ease of miniaturization of the device, and easy colorization. In printing apparatuses such as printers and facsimiles, they are widely used as image forming (recording) means.

  A conventional ink jet printing apparatus is shown in FIG. In the figure, print heads 1K, 1C, 1M, and 1Y are devices that have a plurality of nozzle rows and perform image recording by forming dots on a recording medium by ejecting ink droplets. Different color inks are ejected from different print heads, and a color image is formed on the recording medium by mixing these ink droplets. The print head arrays 1K (black), 1C (cyan), 1M (magenta), and 1Y (yellow) are mounted on the carriage 201, and ink is ejected in this order during one scan. For example, when making red (hereinafter referred to as R), magenta (hereinafter referred to as M) is first landed on the recording medium, and then yellow (hereinafter referred to as Y) is landed on the M dots so as to appear as red dots. In the same manner, in the case of green (hereinafter referred to as G), colors are formed in the order of C and Y, and in the case of blue (hereinafter referred to as B), colors are formed in the order of C and M, respectively. However, since the print heads 1K, 1C, 1M, and 1Y are arranged at a constant interval (P1), for example, when printing solid G, printing Y is delayed by 2 * P1 after printing C. . That is, the Y solid is printed on the C solid. The carriage 201 moves on the sliding shaft by the power from the carriage drive motor 8 being transmitted by the belts 6 and 7. During this operation in the main scanning direction, printing in the digit (sub-scanning) direction is performed.

  The initial position of the carriage 201 is referred to as a home position (hereinafter referred to as HP). Usually, printing is performed by moving the carriage from this HP, and in this example, printing is performed from left to right in FIG. For feeding in the sub-scanning direction, the recording medium is fed by a paper feed motor (not shown). The direction C in the figure is the paper feed direction. Ink is supplied from the ink cassettes 10K, 10C, 10M, and 10Y to the print heads 1Y, 1M, 1C, and 1K on the carriage by the supply tube row 9 for each color.

  FIG. 3 is a schematic diagram illustrating an example of a state in which an ejection port (hereinafter also referred to as a nozzle) disposed in the print head 1Y is viewed from the bottom z direction of the schematic diagram of FIG. In the figure, # 1, # 2,..., # 1280 are 1280 nozzles arranged at a pixel density (1200 dpi) forming 1200 pixels per inch on each print head. The print heads 1M, 1C, and 1K have the same structure.

  The carriage 201 at the home position HP before the start of recording is arranged at a pixel density that forms 1200 pixels per inch of the print head while moving in the x direction (main scanning direction) when a recording start command is issued. Recording with a width of 1280/1200 inches is performed on the paper surface by 1280 nozzles. When the recording to the edge of the sheet is completed, the carriage returns to the home position HP, and again moves for recording in the x direction (main scanning direction). Between the end of the first recording operation and the start of the second recording operation, a paper feed roller (not shown) rotates in the direction of the arrow, thereby 1280/1200 inches in the y direction (sub-scanning, direction C in FIG. 2). Feed the paper. In this way, by repeating 1280/1200 inch recording and paper feeding by the print head for each main scan of the carriage 201, for example, a recorded image for one page can be completed. Note that a recording mode in which one scan recording area is sequentially formed by one scan of the recording head in this way is hereinafter referred to as a one-pass recording mode. This one-pass recording mode is optimal when recording characters and graphic images at high speed.

  FIG. 4 is a schematic diagram when the carriage 201 is viewed from above the printer, and the print heads 1Y, 1M, 1C, and 1K are sequentially arranged.

  In addition to the conventional four colors of cyan (C), magenta (M), yellow (Y), and black (K) in order to form a natural image with higher gradation in an inkjet printing apparatus, For example, the use of 7-color ink that adds three colors of light C (LC), light M (LM), and light Y (LY), which have low ink density, has realized many things that reduce graininess in the highlight area. Has been.

  However, the quality of the recorded image largely depends on the performance of the print head alone. Slight differences for each nozzle that occur during the print head manufacturing process, such as the shape of the discharge port of the print head and the variation in the electrical / thermal converter (discharge heater), affect the amount of ink discharged and the direction of the discharge direction. As a result, the image quality deteriorates as density unevenness of the finally formed recorded image. As a result, there are “white” areas that cannot periodically meet the area factor of 100% in the main scanning direction of the head, and conversely, dots overlap more than necessary or white streaks occur. It will be. These phenomena are usually perceived as uneven density by the human eye.

  Therefore, a multipass printing method has already been devised as a countermeasure against these uneven density, in which all pixels to be recorded in the same recording scan are divided into a plurality of groups and the same recording area is recorded little by little by a plurality of recording scans. Yes. By performing such multi-pass printing, all the recording pixels in the image area that can be recorded in one recording scan are recorded while interweaving dots of different colors in forward printing and backward printing. The negative effects of the order of color placement are eliminated. There is also an effect of recording while drying the ink little by little.

  However, recently, there has been a demand for higher-speed recording and higher image quality, and in the method of recording by simply dividing a plurality of times by multipass as described above, the time cost for recording is more than doubled, and the printing apparatus As such, this situation is not very favorable.

  In recent years, inks with little ink bleeding and media with good absorption have been developed one after another. Against this backdrop, the multi-pass printing method, which produced various effects at the expense of enormous time cost, now has a lot of time loss because it is going to be done only for printing unevenness, and round trips. Therefore, a high-speed one-pass printing method that is performed in one scan is desired.

  Since the 1-pass method forms a single band area with a single scan, the multi-pass forms a single band area with a recording ink duty (ratio) that is driven onto the recording medium at a time. More than printing. For this reason, although the degree of difference varies depending on the properties of the recording medium and the recording liquid, black streaking between passes (between bands) becomes remarkable in a portion with a high printing duty in one-pass printing.

  This adverse effect is even greater in the so-called side-by-side head configuration in which the recording heads that discharge a plurality of different recording inks (cyan, magenta, yellow, etc.) as described above are arranged in the main scanning direction. It will be a thing. This is because the connecting position of each color occurs in the same place.

  The black streaks generated at the boundary between the band and the band as described above are also referred to as connecting streaks or banding, and if this connecting streaks occur, the print quality may be difficult to withstand actual use.

  For this reason, a method has been proposed in which such connecting stripes are eliminated and image quality is improved in one pass. (For example, see Patent Document 1) For this, in the serial scanning method, when the recording head repeatedly scans in the main scanning direction and records an image for each band, it is formed at the joint portion of the recording area for each band. A method for preventing the generation of streaks is described. That is, at least one of the first raster and the final raster of one band recorded by one scan of the recording head is divided into a plurality of unit areas each having a predetermined number of dots, and each unit is determined based on the image data. In this method, printing is performed by thinning out the ink discharge amount of interest in accordance with the sum of the ink discharge amount (duty) of the color of interest in the region and the other ink discharge amounts in the unit region. .

Also, there is a method of suppressing the occurrence of joint stripes by reducing the amount of each ink that is driven into the vicinity of the joint portion based on a certain reduction rate when the scan interval indicated by the band-to-band scan interval information is a predetermined time or more. is there. (For example, see Patent Document 2)
The extent of splicing stripes depends not only on the band edge duty but also greatly on the difference in printing time between bands. For example, during printing, during printing scans to prevent overheating of the head. When control is performed to add a delay, the connecting stripes where the delay has occurred become more prominent than when continuous printing is performed at the normal printing speed. Also, if the carriage scan width is large, there will be a time difference at both ends. That is, it is a method of suppressing the occurrence of connecting stripes by determining the time difference between the time when printing of one band is completed and the time when printing of the next band starts and reducing the amount of each ink that is driven near the connecting portion at a predetermined reduction rate.

  By the way, there is a so-called page printer which analyzes information including color multi-value information of a page description language method in page units and outputs a print in page units as a color ink jet printing apparatus.

  With the advent of inexpensive personal computers recently, an environment has been set up that allows easy handling of full-color characters, graphics, and image data. As a result, color information is used in a wide range of fields such as documents using color, art, and design.

  When recording print data created by an application using such color information on the printing device, the host computer uses the processing function of the host computer, and the host computer matches characters, images, and graphics to the resolution of the printing device. There is a so-called dumb printer or video printer in which the image is developed and then sent to a printing apparatus. This processing method is characterized in that the mechanism on the printer side is simplified and many processes are executed on the host computer side. However, when color information is handled, there is a problem that a large amount of data takes a lot of time for communication, and the throughput may be very low.

  On the other hand, a page description language (abbreviated as Page Description Language, hereinafter abbreviated as PDL) is sent from the host computer as characters, graphics, and images as languages, the PDL is interpreted by the printing device, and various information is stored in the raster memory. There is also a processing method for generating a page image by performing scan conversion (scan conversion). In such a printing apparatus using PDL, print data for one page may be divided into a plurality of bands to save a memory, and bitmap development is performed for each band. The print data used in such a printing apparatus is composed of a plurality of objects with one graphic as one object. These objects are mainly fonts, bitmaps, etc., and are classified according to the difference in their development (hereinafter referred to as rendering) processing methods. Some have hardware rendering means for rendering at high speed. In this case, the PDL data received from the host computer is interpreted for each band, converted into an intermediate code in a form that can be easily processed by hardware, developed by high-speed rendering hardware, and printed. In order to reduce costs, there is also a printing apparatus that does not have hardware rendering means and renders intermediate codes by software alone.

  In such a type of printing apparatus using PDL, depending on the degree of overlap and complexity of the print objects, it may take a long time for the rendering process, and the above-mentioned connecting stripe may be generated. This is particularly noticeable in a printing apparatus that renders intermediate codes only with software.

  For this reason, there is a type of printing apparatus that prepares a rendering memory for one page and renders it for one page before outputting it to a printer engine (print processing unit). However, in this case, a rendering memory for one page must be prepared, and the capacity of the storage device has to be increased particularly in a printing apparatus having a high output resolution, which makes the apparatus very expensive. There was a problem. In addition, the printer engine unit and the controller unit that receives print data and performs rendering cannot operate in parallel, and there is a problem that the first print is delayed.

On the other hand, a method is described in which rendering is performed within a predetermined time by increasing or decreasing the band width in accordance with the complexity of the object. (For example, see Patent Document 3)
8 and 9 are block diagrams showing schematic configurations of the controller unit and printer engine unit of the color PDL ink jet printing apparatus, respectively. First, the function and schematic operation of the controller unit will be described with reference to FIG. The CPU 2601 is connected to the host PC 2611 (2612) via the USB interface 2609 or the IEEE 1394 interface 2610. The RAM 2604 for storing the command signal and image information received from the PC 2611 (2612) is accessed, and the recording operation is controlled based on the information stored in these memories. Instruction information input from the keys of the operation panel 2614 is transmitted to the CPU 2601 via the operation panel interface 2613, and the LED lighting and LCD display of the operation panel 2614 are similarly controlled via the operation panel interface 2613 according to instructions from the CPU 2601. Is done. The expansion interface 2615 is an interface for performing function expansion by connecting an expansion card such as a LAN controller or HDD. The data processing block 2616 interprets the PDL data received from the host PC, performs drawing processing, and further converts it into image formation data of each ink color that conforms to the printer engine specifications, and then passes the printer through the printer engine communication block 2618. Output to the engine (not shown). Similarly, various commands and status information are transmitted and received between the controller and the printer engine via the printer engine communication block 2618. A detailed data processing flow in the data processing block 2616 will be described later.

  Next, the function and operation outline of the printer engine unit will be described with reference to FIG. The printer engine unit is connected to a controller (not shown) via a band memory control block 2712. The CPU 2701 accesses the ROM 2703 that stores the control program, the EEPROM 2704 that stores updatable control programs and processing programs, various constant data, etc., and the RAM 2702 that stores command signals and image information received from the controller (not shown). The recording operation is controlled based on the information stored in these memories. The carriage 2711 is moved by operating the carriage motor 1709 via the output port 2705 and the carriage motor control circuit 2707, and the paper feed paper feed motor 2708 is operated via the output port 2705 and the paper feed motor control circuit 2706. As a result, the paper transport mechanism 2710 such as a transport roller is operated. Further, the CPU 2701 can record a desired image on a recording medium by controlling the band memory control block 2712 and the print head control block 2714 based on various information stored in the RAM 2702 and driving the print head 2715. .

Also, from the power supply circuit (not shown), logic drive voltage Vcc (for example, 3.3V) for operating the CPU and various control circuits, various motor drive voltages Vm (for example, 24V), and heat voltage Vh for driving the print head (For example, 12V) is output.
Japanese Patent Laid-Open No. 11-188898 JP 2002-103575 A JP 2001-146047 A

  In a printing apparatus that performs rendering and printing after inputting, analyzing, and generating intermediate code from a page description language (PDL) sent from a host computer, it has no hardware rendering means in order to keep costs low. There is a printing apparatus that interprets an intermediate code only by software and performs rendering.

  In such a printing apparatus, depending on how the print objects overlap, it may take several seconds or more to render one band, and the above-described conventional method cannot sufficiently eliminate the image connection streak. .

  The present invention has been made to solve the above-described problems. When a predetermined print scan time interval is exceeded by means for measuring a print scan time interval, a rendering result at that time is displayed on the print head. Means for starting printing by using the whole or a part of the above, and the scanning time interval between the printing scan and the printing scan is kept within a predetermined time to reduce the connecting stripe.

  Further, the discharge port of the print head to be used is changed for each print scan so that only a specific portion of the discharge port is not used.

  According to the present invention, in a printing apparatus that generates an intermediate code from PDL data sent from a host computer and performs rendering, the print scan interval is a fixed time regardless of the density and complexity of PDL data object overlap. Even if the rendered band is less than the print head length, it is possible to print with no rendering stripes by using a part of the print head, with less rendering memory. The first print can be obtained in a shorter time.

  Furthermore, when printing using a part of the print head, the print part to be used is configured to be changed for each scan, so that only specific discharge ports are used to prevent uneven head wear. There is an effect that can be.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 7 shows the configuration of the recording section of the ink jet printing apparatus according to the present invention.

  Reference numeral 701 denotes a print head, and ink tanks containing four color inks of black (K), cyan (C), magenta (M), and yellow (Y), respectively, and four independent ink tanks corresponding to each. It is composed of a multi-head composed of two heads (FIG. 4). The number of nozzles for each color is 1280 nozzles. A carriage 702 supports the print head 701 and moves them together with recording. The carriage 702 is at the home position HP shown in the drawing during standby such as a non-recording state. Reference numeral 703 denotes a paper feed roller that rotates while holding the recording paper 705 together with an auxiliary roller (not shown), and feeds the recording paper 705 in the Y direction as needed. Reference numeral 704 denotes a paper feed roller that feeds the recording paper 705 and plays a role of suppressing the recording paper 705 in the same manner as the paper feed roller 703 and the auxiliary roller. Here, the print head 701 has 1280 nozzles arranged in the paper feed direction for each of the four colors K, C, M, and Y (FIG. 3).

  The ink jet printing apparatus includes a controller (FIG. 8) including an interface for exchanging image information and various control information with a host computer and the like, and a data processing block for generating image formation data based on PDL data. ), And a printer engine (FIG. 9) that transports the recording paper and drives the carriage and controls the print head to form an image.

  Next, the flow of data processing will be described with reference to FIG. In FIG. 1, reference numeral 301 denotes a host that creates color information as a color application, converts color data corresponding to the color information into a PDL language format, and sends the converted PDL language data to the printing apparatus controller 302 of the printing apparatus. It is a computer. Here, PDL language data flows between the host computer 301 and the controller 302. There is no problem with the communication form of the PDL language data, such as serial, network, or bus connection. However, in terms of performance, a high-speed communication path is desirable. The PDL language data sent to the controller 302 is temporarily stored in the input buffer (data input buffer) 304.

  The intermediate code generation means 305 of the controller reads and interprets the PDL language data in the input buffer 304 and generates an intermediate code. Here, the intermediate code generation unit 305 creates an intermediate code using the profile 306 for performing image processing, and stores it in the intermediate code memory 307.

  The image processing performed by the intermediate code generation means is usually performed using the monitor color system red, green, and blue RGB (additive color mixture) used in the host computer from yellow, magenta, cyan, Conversion of black to YMCK (subtractive color mixture) is performed.

  The renderer 308 performs the rendering process in real time in synchronization with the video transfer to the printer engine 303 of the printing apparatus by executing the color rendering process with ASIC (application specific IC) hardware, and with a small memory capacity. Banding processing is realized. The renderer 308 may be realized by software instead of hardware for cost reduction. In FIG. 1, the renderer 308 interprets the intermediate code stored in the intermediate code memory 307 and develops it in the band memory 309. The band memory 309 is an area for storing a rendered bit image, and has, for example, 256 lines as a standard size.

  The dot data generation means 310 converts the KCMY color 4-bit data read out from the band memory 309 into KCMY color 1-bit data having an image formation resolution (output resolution) using a halftone dot matrix. For example, dot data having an output resolution of 1200 dpi × 1200 dpi is generated by using a 2 × 2 dot matrix for a rendering resolution of 600 dpi × 600 dpi.

  The bandwidth determination unit 311 reads the type (font, image), print position, and size (height in the sub-scanning direction) of the print object from the intermediate code stored in the intermediate code memory, and renders when the standard size bandwidth is used. Calculate time. The rendering time (the height in the sub-scanning direction) of the drawing data developed by the renderer is compared with this time and the maximum time for preventing the generation of a streak and the effect of the print interval reduction process by the print width determining means described later. Decide whether to use a standard size or smaller.

  The print width determining unit 312 corresponds to the rendering bandwidth determined by the band width determining unit 311 according to a method described later with respect to the print width (height in the sub-scanning direction) in one print scan of the print head and the ejection port for performing printing. It is determined and transmitted to the printer engine 303 of the printing apparatus.

  The print scan interval measuring means 313 is a means for measuring an elapsed time from the previous print scan.

  The processing of the print width determining unit 312 will be described with reference to FIG.

  FIG. 5 is a schematic diagram schematically showing the relationship between the rendering band memory and the print head. Due to recent technological advances, the print head is becoming longer, and the print head length may be larger than the rendering bandwidth. In this example, the rendering resolution and the output resolution are the same, the rendering bandwidth is 256 lines, and the print head length is 1280 lines. In this case, in order to perform conventional one-print scanning, rendering for five bands must be completed.

  The print scan interval measuring means 313 starts time measurement after the end of the previous print scan, and when the predetermined maximum time interval for preventing the generation of the connecting stripe is reached, it instructs the print width determining means 312 to determine the print width. Means 312 instructs printer engine 303 to print the rendered band. For example, the maximum time for not generating a connecting stripe is about 3 seconds. Of course, this varies depending on the process and recording medium.

  In FIG. 6A, if rendering has been completed only up to bands 1 and 2 after 3 seconds from the previous print scan, printing is performed for 512 lines indicated by the head A of the print head. If rendering of bands 3, 4, and 5 is completed within the next 3 seconds in FIG. 6B, printing for 768 lines indicated by the latter half B of the print head is performed. The discharge ports of the print head to be used may be arranged in this order, or may be randomly performed in synchronization with the conveyance of the paper.

  In practice, as in the conventional example (see Patent Documents 1 and 2), at the boundary between the print band and the print band, printing is performed by thinning out dots to reduce the connecting stripes. For this thinning process, at least two lines are required at the boundary of the print band. Therefore, the minimum print bandwidth is 4 lines or more. These values vary depending on the process, recording medium, and the like.

  If there is print data that exceeds the maximum value of the print scan interval measurement even when the print scan interval is reduced by the print width determining unit 312 as described above, a method of reducing the rendering bandwidth itself by the bandwidth determining unit 311 is described. Take.

  Next, the flow of print control processing in the present embodiment will be described using the flowchart of FIG.

  In step S101, the process waits for PDL language data to be transmitted from the host computer. When the PDL language data is transmitted, an intermediate code is created in step S102. An intermediate code is created using the color conversion profile 306 of FIG. 1 and stored in the intermediate code memory 307.

  In step S103, the bandwidth determination unit 311 calculates the rendering time from the type, position, size, and overlap complexity of the band object to be rendered next with the generated intermediate code. Further, if it is predicted that the print width of one print scan will exceed the maximum value of the print scan interval even if the print width determining means 312 divides the print width, the value is made smaller than the standard rendering bandwidth.

  In step S104, rendering for one band is performed. The renderer 308 in FIG. 1 performs rendering from the intermediate code stored in the intermediate code memory 307 and develops it in the band memory 309. Further, the dot data generation unit 310 generates dot data from the rendering output read from the band memory 309.

  Next, in step S105, it is determined whether or not printing for one band is to be performed. If rendering for the head length has been completed, printing is performed in S106. The print scan interval measuring means 313 also prints in S106 if the previous print scan exceeds the predetermined maximum print time interval.

  Next, if printing for the head length is completed in step S107, the process proceeds to step S108, and if not completed, the process is repeated from step S103.

  Finally, it is determined in step S108 whether printing of all pages has been completed. If there is still a rest, repeat from step S102. When all the operations are completed in step S1008, the process returns to step S101 to wait for data reception.

It is a block diagram which shows the basic composition of the data processing of 1st Example of this invention. It is a perspective view which shows the inkjet printing apparatus of a prior art example. FIG. 3 is a schematic diagram illustrating discharge ports arranged in a print head. FIG. 4 is a diagram illustrating an arrangement of print heads on a carriage. FIG. 6 is a schematic diagram illustrating a relationship between a rendering band and a print head when one page is divided into a plurality of rendering bands, rendered, and printed with a plurality of print bands. FIG. 4 is a schematic diagram illustrating a relationship with a rendering band when a print head is divided and used. It is the schematic which shows the recording part in an Example. It is a schematic block diagram of the controller part in an inkjet printing apparatus. It is a schematic block diagram of the engine part in an inkjet printing apparatus. 6 is a flowchart illustrating a flow of print control processing in the embodiment.

Explanation of symbols

301 Host Computer 302 Controller 303 Printer Engine 304 Input Buffer 305 Intermediate Code Generation Unit 306 Profile 307 Intermediate Code Memory 308 Renderer 309 Band Memory 310 Dot Data Generation Unit 311 Bandwidth Determination Unit 312 Print Width Determination Unit 313 Print Scan Interval Measurement Unit

Claims (3)

In a printing apparatus that performs recording on a recording medium in units of bands by ejecting ink from a plurality of ejection ports while scanning the recording head relative to the recording medium.
An acquisition means for acquiring scan time interval information of one scan and the next scan of the recording head;
When the time interval indicated by the scanning time interval information acquired by the acquisition means is a predetermined time or more,
A printing apparatus comprising: selection means for selecting an ejection port used by the recording head; and means for recording with a width narrower than a standard bandwidth by the ejection port selected by the selection means. A printing apparatus that performs drawing processing in units of bands based on input image information, converts the bitmap into an image forming engine, and supplies the image forming engine to a division that manages input image information for one page divided into one or a plurality of bands And a prediction means for predicting, for each band, a rendering required time for bitmap conversion of print data for each band divided by the dividing means,
Based on the rendering time for each band predicted by the prediction means,
Control means for changing and controlling the height of the band divided by the dividing means;
The printing apparatus according to claim 1, further comprising:   3. The printing apparatus according to claim 1, wherein the selection unit selects a different ejection port for each scan of the recording head.

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