JP2005119187A - Image recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate an output timing signal of image data by each line capable of surely determining a writing start position of an image on a recording material and following conveyance variation of the recording material due to a driving force of a driving means. <P>SOLUTION: Each of a high level signal and a low level signal of an output waveform from a pulse encoder 26 for detecting a driving condition of a conveyance roller 16 (driving roller 16A) is converted to the number of clocks of a system clock to be sequentially updated and stored in a memory. Upon a top end of a recording paper 12 is detected by a top end sensor 30, a quasi-timing signal is generated by using the latest converted value. Controlling of recording of an image by a recording head 15 is carried out according to the quasi-timing signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image recording apparatus for recording an image by a recording head in which recording elements are arranged along a direction intersecting the one direction while conveying a recording material in a predetermined direction by a driving force of a driving unit. Is.

  Conventionally, in an image recording apparatus, for example, an ink jet printer, a loaded recording material (recording paper) is transported at a constant speed in a predetermined direction by a driving force of a transport roller.

  In this transport direction, a recording head in which recording elements are arranged in a direction intersecting with the one direction is disposed.

  When the recording paper reaches the position where the recording head is disposed, this is detected by the leading end detection sensor, and recording by the recording head is started by using the leading end detection by the leading end detection sensor as a trigger.

  In recording by the recording head, a signal from an encoder provided on the conveyance roller is used as a reference signal (timing signal). For example, the rising edge of the rectangular wave of the encoder is set as the recording timing (image data output timing) for each line.

  That is, the recording paper conveyance speed is synchronized with the recording timing of the recording head, and even if the recording paper conveyance speed changes due to a change in resolution, the recording timing by the recording head follows this, Image recording is possible.

  Incidentally, the leading edge detection signal for detecting the leading edge of the recording paper as described above and the reference signal from the encoder are asynchronous.

  For this reason, for example, if there is a rising edge of the reference signal from the encoder immediately before the time when the leading edge detection signal is output, the recording timing is delayed until the next rising edge (less than one cycle).

  On the other hand, if the reference signal from the encoder rises immediately after the leading edge detection signal is output, the recording timing is reached without delay.

  For this reason, the tip detection by the tip detection sensor (output of the tip detection signal) is shifted by less than a maximum of one line depending on the timing.

  Such a shift causes a shift in the position of each recording sheet when a plurality of copies are recorded, resulting in a reduction in finished quality. In the case of a color image (including a full-color image), a plurality of colors are recorded in an overlapping manner. However, the shift in the recording position of each color directly leads to a color shift and causes a reduction in image quality.

In order to solve this problem, the first rising edge of the reference clock (for example, the reference clock generated by multiplying the reference signal from the encoder by N times) after the output of the tip detection signal from the tip detection sensor is detected and detected. It has been proposed to reduce the error to 1 / N of the period of the reference signal by synchronizing the reference signal from the encoder and the detection signal based on the reference clock (see Patent Document 1).
JP 2001-150656 A

  However, in Patent Document 1, since a recording timing signal is newly generated from the reference signal from the encoder, it cannot be said that the recording timing signal is faithfully synchronized with the recording paper conveyance speed, and an error in recording start timing is reduced. On the other hand, the transport state of the recording paper during recording when there is a driving error of the driving means for transporting the recording paper is not taken into consideration.

  In other words, the technique of Patent Document 1 is a technique on the assumption that the recording paper is conveyed at a constant speed with respect to the recording timing during recording, while the error of the recording start position is reduced. In particular, no consideration is given to the most important problem of image quality degradation.

  In consideration of the above facts, the present invention can reliably match the writing position of the image on the recording material, and also follows the recording material conveyance unevenness due to the driving force of the driving means. An object is to obtain an image recording apparatus capable of generating an output timing signal of image data.

  According to the first aspect of the present invention, an image is recorded by a recording head in which recording elements are arranged along a direction intersecting the one direction while conveying the recording material in a predetermined direction by a driving force of a driving unit. An image recording apparatus that detects a driving state of the driving unit that conveys the recording material and outputs a driving waveform having periodicity; and an image recording area of the recording material includes the recording material Before reaching the head, it operates under a processing capability determined by a system clock and a front end detecting means for detecting the front end of the recording material in the conveyance direction, and based on a predetermined output timing with respect to input image data, Image recording control means for controlling image recording by the recording element of the recording head; conversion means for converting the detection result detected by the drive state detection means into the number of system clocks; Based on the conversion value updated and stored in the storage means when the storage means that updates and stores the converted value for at least one cycle converted by the conversion means, and when the leading edge of the recording material is detected by the leading edge detection means, Output timing generation means for generating an output timing signal of the image data.

  According to the first aspect of the present invention, when conveyance of the recording material in a predetermined direction is started by the driving force of the driving unit, the driving state detecting unit detects the driving state and performs driving with periodicity. Output the waveform.

  Here, the conversion means converts the drive waveform having the periodicity detected by the drive state detection means into the number of system clocks, and updates and stores the converted value for at least one cycle in the storage means.

  The output timing generation unit generates an output timing signal of image data based on the converted value updated and stored in the storage unit when the leading end of the recording material is detected by the leading end detection unit.

  That is, since there is always one cycle of stock (converted value stored in the storage means) for the output waveform from the drive state detection means, the output timing signal is always at the same timing when detected by the tip detection means. Can be started (for example, the rise time from the detection of the leading edge of the recording material by the leading edge detection means is always constant), and the image areas between the recording materials coincide when recording images on a plurality of recording materials. Can be made.

  According to a second aspect of the present invention, in the first aspect of the invention, the output timing generation means detects from the driving state detection means by sequentially reading the latest converted values updated and stored in the storage means. A pseudo driving waveform delayed within one cycle is generated with respect to the driving waveform having periodicity, and this pseudo driving waveform is applied as the output timing signal.

  According to the second aspect of the present invention, the output timing signal generated by the output timing generation means can be said to be a pseudo drive waveform delayed within one cycle with respect to the drive waveform detected by the drive state detection means. Since the image can be recorded in synchronization with the conveyance state of the recording material, the stability of the image quality of the entire image can be maintained.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the recording head and the leading end detecting means are paired and a plurality of pairs are arranged along the conveying direction of the recording material. It is characterized by being installed.

  According to the third aspect of the present invention, when a plurality of recording heads are arranged along the conveyance direction of the recording material, all of the plurality of recording heads are provided with the tip detection means, The image recording position by the recording head can be unified.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, a plurality of the recording heads are disposed along the recording material conveyance direction, and the plurality of recording heads are provided. On the condition that the pitch between them is known, the one leading edge detecting means is shared by a plurality of recording heads, and the output timing of the image data is corrected based on the known pitch.

  According to the invention described in claim 4, in claim 3, the recording head and the leading end detection means are in a 1: 1 pair. However, if the pitch between the plurality of recording heads is known, Even if the upstream side recording head and the downstream side recording head are associated with the leading edge detection means, it is possible to cope with this by correcting the output timing of the image data based on the pitch between the recording heads.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, C (cyan), M (magenta), a plurality of recording heads sharing the leading edge detection means are necessary for recording a full-color image. It is characterized by being classified for each color of Y (yellow) and K (black).

  According to the invention described in claim 5, in a full-color image, it is necessary to superimpose and record four color images of YMCK on one recording material. In such a full-color image, the shift of the image recording start position leads to a color shift, and the image quality is significantly lowered as compared with the shift between the recording materials of a single color image. In such a case, the present invention in which image recording is started at the same time after the leading edge of the recording material is detected by the leading edge detection means can prevent color misregistration and improve image quality.

  As described above, according to the present invention, the image writing position on the recording material can be reliably matched, and the recording material can be transported evenly due to the driving force of the driving means. This has an excellent effect that a data output timing signal can be generated.

  FIG. 1 is a schematic configuration diagram of an ink jet printer (hereinafter simply referred to as a printer) 10 as an image recording apparatus according to the present embodiment.

  The printer 10 includes a transport system 14 for transporting the recording paper 12 in a planar and horizontal manner, and a recording head 15 provided in the transport path of the recording paper 12 by the transport system.

  The transport system 14 includes a plurality of transport roller pairs 16. The conveying roller pair 16 is provided so as to support the recording paper 12 and to be opposed to the driving roller 16A and a driving roller 16A that is rotationally driven by the driving force of the motor 18 being applied via the belt 20 and the sprocket 22. The driven roller 16B holds the recording paper 12 supported by the driving roller 16A from the upper surface side, and these are intermittently arranged in a skewer shape in a direction intersecting the conveyance direction of the recording paper 12. (See FIG. 2).

  When the recording paper 12 is loaded at a predetermined position by a sheet feeder or the like (not shown) so that the recording surface becomes the upper surface, the recording paper 12 is conveyed substantially horizontally in the direction of arrow A in FIG.

  The recording surface of the recording paper 12 conveyed by the conveying system 14 passes under the recording head 15.

  The recording head 15 has a lower surface facing the recording paper 12 as a nozzle surface 15 </ b> A, and ejects ink from the nozzle surface 15 </ b> A toward the recording paper 12 to record an image.

  On the nozzle surface 15A, as shown in FIG. 3A, a nozzle unit 24 in which a plurality of nozzles 24A (in FIG. 3A, the lead lines are partially displayed) is arranged in a line is arranged on the recording head. A structure arranged in a line in the longitudinal direction of 15 (direction intersecting with the conveyance direction of the recording paper 12) is the simplest structure.

  However, when the nozzles 24A do not exist at a uniform pitch to both ends in the longitudinal direction of the nozzle units 24, the nozzle units 24 can be arranged in a staggered manner as shown in FIG.

  The recording head 15 may be of any ink type and ink droplet ejection method as long as it is an inkjet recording head capable of ejecting ink droplets from the nozzle surface 15A. In addition, the ink jet method is not limited to a method such as a thermal ink jet method, a piezo ink jet, a continuous flow ink jet, or an electrostatic suction ink jet. Furthermore, as the ink to be used, any of water-based ink, oil-based ink, so-called solid ink solid at room temperature, solvent ink, and the like can be applied. The coloring material in the ink may be any pigment or dye.

  As shown in FIG. 1, a pulse encoder 26 is attached to the driving roller 16 </ b> A that is closest to the recording head 15 among the conveying roller pair 16 that constitutes the conveying system 14.

  As is well known, the pulse encoder 26 includes a circular plate in which a plurality of slits (or alternating black / white patterns) are provided on a rotating body (here, the driving roller 16A) at a uniform pitch around the rotating body. A sensor unit that detects transmission / non-transmission (or black / white) of the slit portion of the plate is shown in FIG. 1 as a simplified rectangular block-like rectangular frame.

  The sensor unit of the pulse encoder 26 outputs a rectangular wave according to the rotation of the driving roller 16 </ b> A, and this rectangular wave is input to the controller 28. The controller 28 performs control to maintain the constant speed conveyance of the recording paper 12 such as feedback control of the rotation speed of the motor 18 based on the rectangular wave.

  Further, the rectangular wave from the pulse encoder 26 is applied as a timing signal for each line at the time of image recording to be described later. That is, since the rectangular wave from the pulse encoder 26 faithfully reproduces the transport state of the recording paper 12, even if the transport speed of the recording paper 12 by the transport system 14 changes, the rectangular wave from the pulse encoder 26 By executing image recording based on the waves, it is possible to suppress line pitch unevenness and the like.

  Further, as shown in FIG. 1, the recording head 15 is provided with a leading end detection sensor 30 that detects the leading end of the recording paper 12. The leading edge detection sensor 30 outputs, for example, a high level signal when the recording paper 12 is not present and a low level signal when the recording paper is present. The tip detection sensor 30 is connected to the controller 28, and sends the high level or low level signal to the controller 28.

  Accordingly, when the recording paper 12 is transported by the transport system 14 and the leading edge of the recording paper 12 reaches the detection position of the leading edge detection sensor 30, the signal of the leading edge detection sensor 30 is inverted (high level → low level). The controller 28 can recognize the arrival of the recording paper 12 to the recording head 15.

  Image data is input to the controller 28, and ink is ejected from the nozzle surface 15A based on this image data at a predetermined timing to record an image.

  That is, the tip detection signal from the tip detection sensor 30 (inversion timing from the high level to the low level) serves as a trigger, and the detection position of the tip detection sensor 30 and the recording head 15 (actually, the axis of the nozzle 24A). Image recording is started based on the pitch dimension between them, the conveyance speed of the recording paper 12 by the conveyance system 14, and the rectangular wave (timing signal) from the pulse encoder 26.

  By the way, in the present embodiment, the image recording start timing on each recording paper 12 is the first rising timing of the timing signal after the leading edge detection sensor 28 detects the leading edge of the recording paper 12. In this case, the detection timing of the leading edge of the recording paper 12 by the leading edge detection sensor 30 varies depending on the loading state of the recording paper 12, and is generated based on the output waveform from the pulse encoder 26 provided on the driving roller 16A of the conveying roller 16. The timing signal is not synchronized.

  For this reason, conventionally, the timing signal rises immediately before the leading edge of the recording paper 12 is detected by the leading edge detection sensor 30 and the timing signal rises immediately after the leading edge of the recording paper 12. In some cases, the recording start position shifts (see FIG. 4A).

  Therefore, in the present embodiment, the output waveform from the pulse encoder 26 is not directly applied, but a signal (pseudo timing signal) shifted by one cycle is applied, so that the leading edge of the recording paper 12 by the leading edge detection sensor 30 is applied. The first rising timing of the timing signal comes at a fixed timing after the detection time (see FIG. 4B).

  More specifically, at least one period of the output waveform (rectangular wave) from the pulse encoder 26 is sequentially stored, so that the stored rectangular wave for one period is read out at any time. By repeating this, a pseudo timing signal for image recording is obtained with a signal having a phase shift within one cycle with respect to the output waveform from the pulse encoder 26.

  FIG. 5 is a functional block diagram for generating the pseudo timing signal in the controller 28.

  As shown in FIG. 5, the pulse encoder 26 is connected to the conversion unit 50, and an output waveform (rectangular wave) based on the rotational drive of the drive roller 16 </ b> A generated by the pulse encoder 26 is sent to the conversion unit 50. .

  A system clock is input to the conversion unit 50, and the high-level period and low-level period of the input rectangular wave are converted into the number of clocks.

  The converted high-level clock number and low-level clock number are sent to the converted value update storage unit 52 as a pair of one period.

  The conversion value update storage unit 52 sequentially stores the input high-level clock number and low-level clock number in the memory 54. As a result, the memory 54 always stores the latest number of clocks for one cycle.

  On the other hand, the leading edge detection sensor 30 is connected to the pseudo timing signal generation activation unit 56, and when the leading edge of the recording paper 12 is detected (in this embodiment, when the high level is switched to the low level), the timing of the switching is detected. As a trigger, a pseudo timing signal generation start signal is output to the converted value reading unit 58.

  When the activation signal is input to the converted value reading unit 58, the converted value reading unit 58 reads the number of clocks currently stored in the memory 54 and sends it to the pseudo timing signal generating unit 60.

  This reading is repeated until the image recording is completed (according to the size of the recording paper 12).

  The pseudo timing signal generation unit 60 forms a rectangular wave (pseudo timing signal) based on the number of clocks (high level and low level) input one after another.

  Here, this rectangular wave is the same as the output waveform from the original pulse encoder 26, and the phase is shifted within the range of one cycle (see FIG. 4B).

  On the other hand, since the time from detection by the leading edge detection sensor 30 to generation of the first waveform is always the same, regardless of the output timing of the leading edge detection sensor 30 (the leading edge detection timing of the recording paper 12). A pseudo timing signal synchronized with the output signal of the tip detection sensor 30 is generated.

  The rectangular waves (pseudo timing signals) generated one after another are sent to the image recording control unit 62, and the image recording control unit 62 controls the recording elements provided in the recording head 15 to input image data. Based on the above, an image is recorded on the recording paper 12.

  Hereinafter, the operation of the present embodiment will be described with reference to the flowchart of FIG.

  In step 100, it is determined whether an image recording instruction has been issued. If the determination is negative, it is not necessary to generate a pseudo timing signal, and thus this routine ends.

  If an affirmative determination is made in step 100, the process proceeds to step 102 and driving of the transport roller 16 (drive roller 16 </ b> A) is started.

  By driving the driving roller 16A, the recording paper 12 loaded in advance at a predetermined position is conveyed at a substantially constant speed while maintaining flatness, and gradually approaches the recording head 15.

  In the next step 104, the output waveform (rectangular wave) from the pulse encoder 26 provided on the driving roller 16A of the conveying roller 16 is converted into the number of system clocks.

  That is, the signal from the pulse encoder 26 is a high-level and low-level binarized rectangular wave, and the high-level period and the low-level period are converted into the number of system clocks, respectively.

  The conversion result is stored in the memory 54 in step 106.

  In the next step 108, it is determined whether or not the leading edge detection sensor 30 has detected the leading edge of the recording paper 12.

  If a negative determination is made in step 108, the process returns to step 104 and steps 104 and 106 are repeated.

  That is, while a negative determination is made in step 108 (while the recording paper 12 has not reached the leading edge detection sensor 30), conversion of the output waveform of the pulse encoder 26 for each cycle into the number of clocks is repeated. In addition, the memory 54 is updated and stored so that the latest number of clocks for one cycle (the number of clocks indicating a high level period and the number of clocks indicating a low level period) remain.

  If an affirmative determination is made in step 108, the process proceeds to step 110, where the number of clocks for one cycle stored in the current memory 54 is read, and a pseudo timing signal (for one cycle) is read based on the read clock number. ) Is generated (step 112).

  In the next step 114, the pseudo timing signal for one cycle generated is output to the image recording control unit 62, and the process proceeds to step 116.

  In the next step 116 and step 118, the conversion and storage of the number of clocks are executed in the same manner as in the above step 104 and step 106, and the process proceeds to step 120. In step 120, it is determined whether or not the image recording is completed. If the determination is negative, it is determined that the image recording is in progress, the process returns to step 110, and the above steps 110 to 118 are repeated. That is, generation of a pseudo timing signal for one cycle and output to the image recording control unit 62 are repeated, and as a result, a continuous rectangular wave pseudo timing signal is output to the image recording control unit 62.

  Since this pseudo timing signal is the same as the waveform output from the pulse encoder 26 and is out of phase within one cycle, image recording by the recording head 15 is synchronized with the conveyance speed of the recording paper 12. Will be executed.

  If an affirmative determination is made in step 120, it is determined that the image recording has been completed, the process proceeds to step 122, the drive of the transport roller 16 (drive roller 16A) is stopped, and this routine ends.

  As described above, in this embodiment, the high-level signal and the low-level signal of the output waveform from the pulse encoder 26 that detects the driving state of the transport roller 16 (drive roller 16A) are represented by the number of system clocks. Are converted and stored in sequence, and when the leading edge of the recording paper 12 is detected by the leading edge detection sensor 30, a pseudo timing signal is generated using the latest converted value. Based on this pseudo timing signal, the recording head 15 Since the image recording control is executed by the image sensor, the image recording can always be executed at the same timing after the recording paper 12 is detected by the leading edge detection sensor 30, and the shift of the image area between the recording papers can be prevented. can do.

  Further, since the pseudo timing signal is always generated using the latest converted value for the output waveform from the pulse encoder 26, the conveyance of the recording paper 12 by the conveyance roller 16 driven at a constant speed is usually performed. Even if the speed unevenness occurs for some reason, the image recording timing can be changed following the speed unevenness. For this reason, the stability of the quality of the finished image can also be maintained.

  In the present embodiment, the printer 10 including one recording head 15 and one leading edge detection sensor 30 has been described as an example. However, the number of recording heads 15 and the number of leading edge detection sensors 30 are not limited to the printer. Various modifications can be made according to the ten specifications. Hereinafter, variations of the combination of the recording head 15 and the tip detection sensor 30 will be described as modified examples.

(Modification 1)
FIG. 7 shows an example of a printer 10 </ b> A in which a plurality of recording heads 15 are arranged along the conveyance direction of the recording paper 12 and a leading edge detection sensor 30 is provided for each. Since such a configuration is a plural form of the configuration of FIG. 1, the control such as the generation of the pseudo timing signal may be executed independently by each recording head 15 and the leading end detection sensor 30.

(Modification 2)
FIG. 8 shows an example in which the present invention is applied to a full-color printer 10B. One color of Y (yellow), M (magenta), C (cyan), and K (black) is used by two recording heads 15. Is in charge of. Therefore, a total of eight recording heads 15 are arranged along the conveyance direction of the recording paper 12 in the printer 10B of the second modification.

  By the way, since two recording heads 15 handle one color, the image data for each color is divided and sent to the recording head 15 that handles each color. For example, as shown in FIG. 3, in the recording head in which the nozzles 24A are arranged in a line, the nozzle 24A of the other recording head 15 is located at a position that is 1/2 the pitch between the nozzles 24A of the one recording head 15. If the relative position is determined in this way, the resolution can be doubled.

  As shown in FIG. 4, when the nozzle units 24 must be arranged in a staggered manner, if the respective recording heads 15 correspond to each other, the nozzle units 24 are closely arranged on the single recording head 15. This eliminates the need to improve assembly workability.

  Here, in the printer 10B of the second modification, one tip detection sensor 30 is provided for the two recording heads 15 assigned to each color. Along with this, the pulse encoder 26 is also provided corresponding to only the recording head 15 located on the upstream side of the recording head 15 of each color.

  That is, if the distance between the recording heads 15 is the same color, they are close to each other, so that sufficient positional accuracy is ensured by correcting (delaying) the pseudo timing signal of the recording head 15 on the downstream side according to this distance. can do. Thereby, compared with the printer 10 of the modification 1, the control burden can be reduced to ½ by simple calculation.

1 is a schematic configuration diagram of a printer according to an embodiment. 2 is a plan view of the printer according to the present embodiment. FIG. The shape of the nozzle face of the recording head is shown, (A) is a nozzle unit single-row arrangement pattern, and (B) is a nozzle unit staggered arrangement pattern. (A) is a timing chart at the start of image recording based on a conventional timing signal, and (B) is a timing chart at the start of image recording based on a pseudo timing signal according to the present embodiment. It is a functional block diagram for pseudo timing signal generation in a controller. 5 is a control flowchart mainly for generating pseudo timing signals in image recording control. FIG. 9 is a schematic configuration diagram of a printer according to a first modification. FIG. 9 is a schematic configuration diagram of a printer according to Modification 2.

Explanation of symbols

10 Printer (image recording device)
12 Recording paper (recording material)
14 Transport system 16 Transport roller pair 18 Motor (drive means)
20 belt 22 sprocket 16A driving roller 16B driven roller 15 recording head 15A nozzle surface 24A nozzle (recording element)
24 Nozzle unit 26 Pulse encoder (drive state detection means)
28 controller 30 tip detection sensor (tip detection means)
50 Conversion unit (conversion means)
52 Conversion Value Update Storage Unit 54 Memory (Storage Unit)
56 Pseudo Timing Signal Generation Start Unit 58 Conversion Value Reading Unit 60 Pseudo Timing Signal Generation Unit (Output Timing Generation Unit)
62 Image recording control unit (image recording control means)

Claims (5)

An image recording apparatus for recording an image by a recording head in which recording elements are arranged along a direction intersecting the one direction while conveying a recording material in a predetermined direction by a driving force of a driving unit,
A driving state detecting unit that detects a driving state of the driving unit that conveys the recording material and outputs a driving waveform having periodicity;
A leading end detecting means for detecting a leading end of the recording material in the transport direction before the image recording area of the recording material reaches the recording head;
An image recording control unit that operates under a processing capability determined by a system clock and controls image recording by a recording element of the recording head based on a predetermined output timing with respect to input image data;
Conversion means for converting the detection result detected by the drive state detection means into the number of system clocks;
Storage means for updating and storing a converted value for at least one cycle converted by the converting means;
An output timing generation unit that generates an output timing signal of the image data based on a conversion value that is updated and stored in the storage unit when the leading end portion of the recording material is detected by the leading end detection unit;
An image recording apparatus.   The output timing generation means sequentially reads the latest conversion value updated and stored in the storage means, thereby delaying the drive waveform having periodicity detected by the drive state detection means within one cycle. The image recording apparatus according to claim 1, wherein a pseudo drive waveform is generated and the pseudo drive waveform is applied as the output timing signal.   3. The image recording apparatus according to claim 1, wherein a plurality of pairs of the recording head and the leading end detection unit are arranged along the conveying direction of the recording material.   On the condition that a plurality of the recording heads are arranged along the recording material conveyance direction and the pitch between the plurality of recording heads is known, the one leading edge detecting means is a plurality of recording heads. The image recording apparatus according to claim 1, wherein the output timing of image data is corrected based on the known pitch that is shared.   A plurality of recording heads sharing the leading edge detection means are classified for each color of C (cyan), M (magenta), Y (yellow), and K (black) necessary for recording a full-color image. The image recording apparatus according to claim 4, wherein:

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