JP2009083381A - Image recorder and method for setting ejection control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recorder capable of preventing degradation of image quality by properly setting a carriage moving direction on ejecting ink. <P>SOLUTION: The velocity features of the carriage 38 performing its forward and backward movements can be obtained (S30) by test-driving (S20) the carriage 38. From the velocity features velocity Vc in the horizontal direction portion when the ink droplets are ejected is calculated as a prediction value (S60). From the velocity Vc, a flying distance D and an amount of shift ΔD in landing position of a nozzle row for magenta 40M and a nozzle row for yellow 40Y in the horizontal direction, are calculated (S70), and the shift amounts ΔDf and ΔDr are added in absolute value to calculate the evaluation values Ef and Er (S80). An average value [Ef], [Er] of the calculated evaluation values is evaluated for forward and backward movements (S100). The control method is set for ejecting ink droplets in the moving direction of the carriage 38 based on the smaller evaluation value (S110, S120). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention sets the ink droplet ejection control during image recording to either the first control for ejecting ink droplets when the carriage moves in the forward direction or the second control for ejecting ink droplets when the carriage moves in the backward direction. The present invention relates to an image recording apparatus and an ejection control setting method.

  2. Description of the Related Art As an image recording apparatus such as a printer, a facsimile machine, a copier, or a multifunction machine having both functions, an inkjet recording type image recording apparatus is known. This type of image recording apparatus records an image on a recording sheet by ejecting ink droplets from the recording head toward the recording sheet.

  The image recording apparatus is provided with a carriage supported so as to be able to reciprocate in a direction (scanning direction) perpendicular to the conveyance direction of the recording paper. The recording head is mounted on the carriage and moves in the same direction as the carriage reciprocates. By ejecting ink droplets from the recording head while the carriage is moving, a line-shaped image is recorded on the recording paper. A line-like image is recorded each time the recording paper is intermittently conveyed, whereby a continuous image is recorded on the recording paper.

  In such an image recording apparatus, recording is performed whenever the carriage moves in the forward direction (hereinafter abbreviated as “forward movement”) and moves in the backward direction (hereinafter abbreviated as “reverse movement”). One having a function of recording an image by ejecting ink droplets from a head is known (see Patent Documents 1 to 3). This function is called a bidirectional printing function (bidirectional recording function).

  The bi-directional printing function records images when the carriage moves in the forward and backward directions, and has the advantage of shortening the recording time compared to performing image recording in only one direction. There is a problem of being inferior. This problem is caused by the difference in speed fluctuation that occurs during carriage movement between the forward movement and the backward movement of the carriage. Therefore, conventionally, when performing high-quality printing like photographic printing, control is performed so that ink droplets are ejected only when the carriage moves in one of the preset directions (forward or backward). ing.

JP 2005-138323 A JP 2005-335343 A JP 2007-152784 A

  However, even in the case of an image recording apparatus manufactured according to a predetermined specification, the direction in which the carriage speed variation decreases is not necessarily the same for all manufactured image recording apparatuses. Carriage speed fluctuations are caused by various factors such as motor cogging torque, eccentricity of the motor shaft or pulley shaft, mounting error of the carriage drive mechanism, and rigidity of the housing of the device. In some cases, the fluctuation or the like is larger than that in the backward movement, and conversely, the speed fluctuation or the like in the backward movement may be larger than that in the forward movement. In this case, if the moving direction of the carriage in which ink is ejected during high-quality printing is set to the direction with the larger speed fluctuation without considering the difference in speed fluctuation during reciprocating motion, the image is printed regardless of high-quality printing. There can be a problem that the quality is significantly reduced.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a reduction in image quality by appropriately setting the moving direction of the carriage when ejecting ink. An object of the present invention is to provide an image recording apparatus capable of performing the above.

(1) The present invention includes a carriage that reciprocates in a predetermined direction by receiving a driving force from a driving source, and a first nozzle and a second nozzle that are mounted on the carriage and that are separated in the movement direction of the carriage, A recording head that ejects ink droplets from each nozzle, a first acquisition unit that acquires the first speed characteristic of the carriage during forward movement, and a second that acquires the second speed characteristic of the carriage during backward movement. Based on the first speed characteristic, the acquisition means, the storage means for storing the first speed characteristic and the second speed characteristic acquired by the first acquisition means and the second acquisition means in a storage medium, A first speed of the carriage corresponding to a first timing for ejecting ink droplets from a first nozzle to a predetermined setting position is obtained, and ink droplets are ejected from the second nozzle to the setting position. And a first evaluation value based on a difference between the first speed and the second speed obtained by the first computing means. Based on the second speed characteristic, a third speed of the carriage corresponding to a third timing for ejecting ink droplets from the first nozzle to the set position is obtained, and the second speed is obtained. A third computing means for obtaining a fourth speed of the carriage corresponding to a fourth timing for ejecting ink droplets from two nozzles to the set position; the third speed obtained by the third computing means; and the third speed. A fourth computing means for obtaining a second evaluation value based on a difference from the four speeds; a first evaluation value obtained by the second computing means; and a second evaluation value obtained by the fourth computing means. Based on the comparison means and the comparison result by the comparison means, the ink droplet ejection control at the time of image recording, the first control for ejecting ink droplets from the nozzles when the carriage moves in the forward direction, or the carriage The image recording apparatus is configured to include setting means for setting to any one of the second control for ejecting ink droplets from the respective nozzles when moving in the backward direction.

  With this configuration, it is possible to reliably determine which speed fluctuation is smaller between the speed fluctuation when the carriage moves in the forward direction and the speed fluctuation when the carriage moves in the backward direction. Therefore, it is easy to set so that ink droplet ejection control is performed in the moving direction with the smaller speed fluctuation. Thereby, the quality of the recorded image can be improved.

(2) In the case where a plurality of the set positions are determined, the first calculation means obtains the first speed at each of a plurality of first timings for ejecting ink droplets to the plurality of set positions, The second velocity is obtained for each of a plurality of second timings for ejecting ink droplets from the second nozzle to the plurality of set positions. In addition, the second calculation means includes a plurality of first values based on a difference between the first speed and the second speed corresponding to the same set position obtained by the first calculation means for each of the plurality of setting positions. An evaluation value is obtained. The third calculating means obtains the third speed for each of a plurality of third timings for ejecting ink droplets to each of the plurality of set positions, and performs ink from the second nozzle to each of the plurality of set positions. The fourth speed is obtained for each of a plurality of fourth timings for ejecting droplets. In addition, the fourth calculation means includes a plurality of second values based on a difference between the third speed and the fourth speed corresponding to the same set position obtained by the third calculation means for each of the plurality of setting positions. An evaluation value is obtained.

  Since the comparison unit compares the plurality of first evaluation values and the plurality of second evaluation values obtained in this way, the comparison accuracy by the comparison unit is improved.

(3) The first acquisition unit acquires the first speed characteristic for each of a plurality of forward movements, and the second acquisition unit acquires the second speed characteristic for each of a plurality of backward movements. To do. In this case, the second calculation means obtains a plurality of first evaluation values based on a difference between the first speed and the second speed obtained by the first calculation means for each of the plurality of first speed characteristics. In addition, the plurality of first evaluation values are averaged. Further, the fourth calculation means obtains a plurality of second evaluation values based on a difference between the third speed and the fourth speed obtained by the third calculation means for each of the plurality of second speed characteristics. In addition, the plurality of second evaluation values are averaged.

  In this way, by averaging the plurality of first evaluations and the plurality of second evaluations obtained, the comparison accuracy by the comparison means is stabilized.

(4) The first acquisition unit acquires the first speed characteristic for each of a plurality of forward movements, and the second acquisition unit acquires the second speed characteristic for each of a plurality of backward movements. To do. In this case, the storage means averages the plurality of first speed characteristics acquired by the first acquisition means, averages the plurality of second speed characteristics acquired by the second acquisition means, and stores the memory. It is stored in a medium. The first calculation means obtains the first speed and the second speed based on the averaged first speed characteristic stored in the storage medium. The third calculation means obtains the third speed and the fourth speed based on the averaged second speed characteristic stored in the storage medium.

  Thereby, since the first evaluation and the second evaluation are stabilized, the accuracy of the comparison result by the comparison means is improved.

(5) The first evaluation value is obtained on the basis of the first speed, and a separation distance from the first predicted landing position of the ink droplet ejected from the first nozzle at the first timing to the set position. It may be a difference between a separation distance from the second predicted landing position of the ink droplet ejected from the second nozzle at the second timing to the set position, which is obtained based on the second speed. The second evaluation value is obtained based on the third speed, and a separation distance from a third predicted landing position of the ink droplet ejected from the first nozzle at the third timing to the set position; It may be a difference between a separation distance from the fourth predicted landing position of the ink droplet ejected from the second nozzle at the third timing to the set position, which is obtained based on the third speed.

(6) The comparison means compares the average value of the plurality of first evaluation values obtained by the second calculation means with the average value of the plurality of second evaluation values obtained by the fourth calculation means. Is.

  Thereby, even if there is a variation in each evaluation value, the comparison determination by the comparison means is performed based on the average value, so that it is possible to prevent a reduction in comparison accuracy due to a variation in each evaluation value.

(7) The image recording apparatus of the present invention is used when converting image data input to the image recording apparatus into data of a predetermined format capable of image recording, and includes first conversion information corresponding to the first control and Conversion information storage means storing second conversion information corresponding to the second control, reading means for reading out conversion information corresponding to the ink droplet ejection control set by the setting means from the conversion information storage means, and It is preferable to further comprise image conversion means for converting the image data based on the conversion information read by the reading means.

  Thereby, for example, the process of converting RGB format image data input to the image recording apparatus into CMY data capable of image recording can be performed with high accuracy using optimum conversion information.

(8) The image recording apparatus of the present invention further includes a transmission mechanism that transmits the driving force from the driving source to the carriage. The transmission mechanism is rotatably provided at one end of the carriage movement range, is connected to an output shaft of the drive source, and is rotatably provided at the other end of the carriage movement range. A driven pulley supported slidably in the moving direction of the carriage, a winding member wound around the drive pulley and the driven pulley, and urging the driven pulley in a direction in which the tension of the winding member increases. And an urging member.

  When the driving force of the driving source is transmitted to the carriage by such a transmission mechanism, it is considered that the speed variation of the carriage is caused by an attachment error or deformation of each member or variation of the urging force of the urging member. . Accordingly, in the image recording apparatus having the above transmission mechanism, for example, even if the speed fluctuation in the forward direction is designed to be small, when the image recording apparatus is actually assembled, the speed fluctuation in the backward direction becomes smaller. Occurs. That is, the present invention is suitably used for an image recording apparatus having such a transmission mechanism.

(9) The first nozzle is for ejecting magenta ink, and the second nozzle is for ejecting yellow ink.

  A color image recorded on a recording medium such as a recording sheet mainly displays a magenta color and a yellow color clearly. Accordingly, the first evaluation value and the second evaluation value are obtained based on the first nozzle for ejecting magenta ink and the second nozzle for ejecting yellow ink, and these evaluation values are compared. In addition, if ink ejection control is set, the quality of the color image actually recorded on the recording medium can be maintained at a high quality.

(10) The recording head further includes a third nozzle from which ink droplets are ejected. In this case, it is preferable that the first nozzle and the second nozzle are arranged to be separated in the carriage movement direction with the third nozzle interposed therebetween.

  For example, when the recording head ejects magenta, cyan, and yellow color inks, and the nozzles corresponding to each color ink are arranged in the order of magenta nozzle, cyan nozzle, and yellow nozzle, That is, when the magenta nozzle and the yellow nozzle are arranged with the cyan nozzle interposed therebetween, the arrangement interval between the magenta nozzle and the yellow nozzle is large. In this case, the amount of deviation in the landing position between the ink ejected from the magenta nozzle and the ink ejected from the yellow nozzle is expected to be larger than the amount of deviation due to the combination of the other color inks. Therefore, in this case, the magenta nozzle and the yellow nozzle arranged on both sides with the cyan nozzle interposed therebetween, that is, the first nozzle spaced in the carriage movement direction with the third nozzle interposed therebetween. In addition, by obtaining the first evaluation value and the second evaluation value based on each of the second nozzle and the second nozzle, the reliability of the evaluation value itself is increased. As a result, the quality of the color image actually recorded on the recording medium is improved. Can be maintained.

(11) The present invention provides a carriage having a carriage capable of reciprocating in a predetermined direction by receiving a driving force from a driving source, and a first nozzle and a second nozzle mounted on the carriage and separated in the movement direction of the carriage. The present invention is applied to an image recording apparatus having a head, and can be regarded as an ejection control setting method for setting ink droplet ejection control for ejecting ink droplets from the nozzles. That is, a first acquisition step for acquiring the first speed characteristic of the carriage during forward movement, a second acquisition step for acquiring the second speed characteristic of the carriage during backward movement, the first acquisition step, and A storage step of storing the first speed characteristic and the second speed characteristic acquired in the second acquisition step in a storage medium, and one predetermined from the first nozzle based on the first speed characteristic Alternatively, a first speed of the carriage corresponding to a first timing for ejecting ink droplets to a plurality of set positions is obtained, and a second timing for ejecting ink droplets from the second nozzle to the set positions is obtained. A first calculation step for obtaining the second speed of the carriage, and a first evaluation based on a difference between the first speed and the second speed obtained by the first calculation step. A second calculation step for determining a value, and a third speed of the carriage corresponding to a third timing for ejecting ink droplets from the first nozzle to the set position based on the second speed characteristic; A third computation step for obtaining a fourth speed of the carriage corresponding to a fourth timing for ejecting ink droplets from the second nozzle to the set position; the third speed obtained by the third computation step; A fourth calculation step for obtaining a second evaluation value based on a difference from the fourth speed, the first evaluation value obtained by the second calculation step, and the second evaluation value obtained by the fourth calculation step; Based on the comparison step and the comparison result in the comparison step, the ink droplet ejection control during image recording is performed when the carriage is moved in the forward direction. And a setting step for setting to either a first control for discharging ink droplets from the nozzle or a second control for discharging ink droplets from the nozzles when the carriage moves in the backward direction. Also good.

  According to the present invention, it is possible to set a moving direction in which speed fluctuation is small as a direction in which ink droplet ejection control is performed. Therefore, high image quality can be realized in the image recording apparatus.

  Hereinafter, a preferred embodiment of the present invention will be described with appropriate reference to the accompanying drawings. Note that the embodiment described below is merely an example embodying the present invention, and it is needless to say that the embodiment can be appropriately changed without departing from the gist of the present invention.

[Explanation of drawings]
FIG. 1 is a perspective view showing an external configuration of the multifunction machine 1. FIG. 2 is a partially enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 3 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. FIG. 4 is a schematic diagram schematically showing the outline of the configuration of the belt drive mechanism 46. FIG. 5 is a bottom view showing the nozzle formation surface of the recording head 39. FIG. 6 is a block diagram illustrating a main configuration of the main control unit 100 of the printer unit 2. FIG. 7 is a block diagram showing the configuration of the ASIC 107 in detail. FIG. 8 is a flowchart illustrating an example of the procedure of the discharge control setting process for setting the discharge control by the recording head 39. FIG. 9 is a flowchart illustrating an example of a procedure of image conversion processing using a conversion table. FIG. 10 is a diagram showing speed characteristics Vf and Vr during reciprocating motion. FIG. 11 is a diagram illustrating the deviation amounts ΔDf and ΔDr during the reciprocating motion for each sampling time. FIG. 12 is a diagram for explaining the horizontal flight distance D from the discharge point H to the landing point. FIG. 13 is a diagram for explaining the deviation amount ΔD of the landing point of the ink droplet due to the speed fluctuation on the carriage 38.

[Multifunction machine 1]
The multi-function device 1 is a multi-function device (MFP: Multi Function Product) that integrally includes a printer unit 2 which is an example of an image recording apparatus of the present invention and a scanner unit 3, and includes a print function, a scan function, and a copy function. Functions, facsimile functions, etc. The multi-function device 1 is generally formed in a rectangular parallelepiped shape. A printer unit 2 is disposed at a lower portion thereof, and a scanner unit 3 is disposed at an upper portion thereof. Each of the above functions is realized when a later-described main control unit 100 (see FIG. 6) provided in the multifunction machine 10 controls the printer unit 11 and the scanner unit 12.

  The printer unit 2 of the multifunction machine 1 records (prints) an image or a document on a sheet based on predetermined print data. The printer unit 2 has an opening 9 formed in the front. The paper feed tray 20 and the paper discharge tray 21 are provided in two upper and lower stages inside the opening 9. The recording paper stored in the paper supply tray 20 is fed into the printer unit 2 and a desired image is recorded on the recording paper. Thereafter, the recording paper on which the image has been recorded is discharged to the paper discharge tray 21.

  The scanner unit 3 is configured as a so-called flat bed scanner. A document cover 30 as a top plate of the multifunction device 1 is provided on the upper portion of the scanner unit 3 so as to be freely opened and closed. A platen glass (not shown) and a plurality of CIS image sensors are provided below the document cover 30. The plurality of CIS image sensors are mounted on a carriage (not shown) in a state of being arranged in a line in the depth direction (arrangement direction) of the multifunction device 1. The carriage is configured to be movable in a direction (moving direction) perpendicular to the arrangement direction along the back surface of the platen glass. In the process of moving the carriage in the moving direction, the image of the document placed on the platen glass is read by the CIS image sensor. In order to realize the present invention, the scanner unit 3 has an arbitrary configuration, and a detailed description thereof is omitted here.

  As shown in FIG. 1, an operation panel 4 for operating the printer unit 2 and the scanner unit 3 is provided in the upper front portion of the multifunction machine 1. The operation panel 4 includes an operation device such as a push button switch, a liquid crystal display panel, and the like. The multi-function device 1 operates based on an instruction input via the operation panel 4. When the multifunction device 1 is connected to an external computer, the multifunction device 1 also operates based on an instruction transmitted from the computer via a printer driver or a scanner driver. For example, when the print mode of the printer unit 2 is set to either the high image quality print mode or the low image quality print mode via the printer driver, the printer unit 2 performs an operation according to the set print mode. It is controlled by the main control unit 100. Specifically, when the high quality print mode is set, the recording head 39 (the recording head of the present invention) is moved when the carriage 38 (an example of the carriage of the present invention, see FIG. 2) moves in a predetermined direction. (See FIG. 2 for an example.) When the low-quality print mode is set, control is performed to eject ink from the recording head 39 when the carriage 38 moves in the forward direction and the backward direction. .

[Printer unit 2]
As shown in FIG. 2, a paper feed tray 20 is provided on the bottom side of the multifunction machine 1. A paper feed roller 25 is provided above the paper feed tray 20. A base shaft 29 is supported on a frame (not shown) of the printer unit 2. The base end of the paper feeding arm 26 is rotatably supported by the base shaft 29. The paper feed roller 25 is rotatably supported at the tip of the paper feed arm 26. An LF motor 95 (see FIG. 6) for rotating the paper feed roller 25 is connected to the base shaft 29. The paper feed arm 26 is provided with a gear drive mechanism 27 that transmits the rotational driving force of the LF motor 95 input from the base shaft 29 to the paper feed roller 25. The rotational driving force of the LF motor 95 is transmitted to the paper feed roller 25 via the base shaft 29 and the gear drive mechanism 27. As a result, the paper feed roller 25 is driven to rotate.

  When the sheet feeding roller 25 is rotated and pressed against the recording sheet on the sheet feeding tray 20, the uppermost recording sheet is fed by the frictional force between the roller surface of the sheet feeding roller 25 and the recording sheet. It is sent out to the back side (the right side in FIG. 2) of the paper tray 20. The leading edge of the recording paper abuts on the inclined plate 22 and is guided upward. A sheet conveyance path 23 extends from the inclined plate 22. Specifically, the sheet conveyance path 23 is directed upward from the inclined plate 22 and bent to the front side (left side in FIG. 2) of the multifunction machine 1, and then from the back side to the front side of the multifunction machine 1. And extends to the paper discharge tray 21 through the lower part of the image recording unit 24. Accordingly, the recording paper stored in the paper feed tray 20 is guided by the paper conveyance path 23 so as to make a U-turn from the lower side to the upper side, reaches the image recording unit 24, and after image recording is performed by the image recording unit 24. The paper is discharged to the paper discharge tray 21.

  As shown in FIG. 2, an image recording unit 24 is disposed in the paper transport path 23. The image recording unit 24 includes an inkjet recording type recording head 39 and a carriage 38 on which the recording head 39 is mounted. The carriage 38 is supported so as to be slidable in a direction perpendicular to the recording sheet conveyance direction (a direction perpendicular to the paper surface of FIG. 2).

  The recording head 39 selectively ejects fine ink particles toward a recording sheet conveyed on the platen 42. The platen 42 is disposed so as to face the lower surface of the carriage 38. As a method of ejecting ink, a method of ejecting ink by deformation of a piezoelectric element (piezo element) or a method of ejecting ink by bubbles generated by applying heat to the ink can be employed. The recording head 39 is disposed on the lower surface of the carriage 38, and the nozzles 40 (see FIG. 5) of the recording head 39 are exposed on the lower surface of the carriage 38. Ink of each color is supplied to the recording head 39 from an ink cartridge (not shown) arranged inside the multifunction device 1.

  As shown in FIG. 5, the recording head 39 is provided with a nozzle 40 on the lower surface thereof. Specifically, on the lower surface of the recording head 39, a plurality of nozzle arrays corresponding to inks of each color of cyan (C), magenta (M), yellow (Y), and black (Bk) are arrayed in the recording sheet conveyance direction. It is installed. In the figure, the direction from the bottom to the top is the recording paper conveyance direction, the left direction is the forward direction of the carriage 38, and the right direction is the backward direction of the carriage 34.

  The nozzles for the respective color inks are arranged in the conveyance direction of the recording paper, and the nozzle rows for the respective color inks are arranged in the moving direction of the carriage 34. Specifically, on the lower surface of the recording head 39, the magenta nozzle row 40M (an example of the first nozzle of the present invention) and the cyan nozzle are arranged in the forward direction from the backward end portion (the right end portion in FIG. 5). A nozzle row 40C (an example of the third nozzle of the present invention), a yellow nozzle row 40Y (an example of the second nozzle of the present invention), and a black nozzle row 40Bk are arranged in that order. In other words, the nozzle rows are arranged in the moving direction of the carriage 38. Regarding the color ink nozzle rows, the nozzle row 40M and the nozzle row 40Y are arranged on the carriage 38 with the nozzle row 40C interposed therebetween. Arranged in the direction of movement. In the present embodiment, the nozzle rows 40C, 40M, and 40Y are arranged at equal intervals with a distance d, and the distance d between the nozzle rows 40Y and 40Bk is avoided in order to avoid color mixing with black ink. Separated by a longer distance. The number of nozzles 40, the pitch in the transport direction or the reciprocating direction, and the like are appropriately set in consideration of the resolution of the recorded image. It is also possible to increase or decrease the number of rows of nozzles 40 according to the type and number of color inks.

  When the carriage 38 reciprocates while the recording head 39 is mounted on the carriage 38, the recording head 39 reciprocates in a direction perpendicular to the recording sheet conveyance direction. While the carriage 38 is reciprocated, the recording head 39 is controlled by a head drive circuit 113 (see FIG. 6) described later, and each color ink is selectively ejected from the nozzle 40 of the recording head 39 as a minute ink droplet. The As a result, an image is recorded on the recording paper conveyed on the platen 42. The head drive circuit 113 controls the ink discharge amount and discharge timing, and details thereof will be described later.

  As shown in FIG. 3, a pair of guide rails 43 and 44 are arranged on the upper side of the sheet conveyance path 23. These guide rails 43 and 44 are opposed to each other with a predetermined distance in the recording paper conveyance direction (from the upper side to the lower side in FIG. 3) and are orthogonal to the recording paper conveyance direction (left and right in FIG. 3). Direction). The guide rails 43 and 44 are provided in the casing of the printer unit 2 and constitute a part of a frame constituting the printer unit 2.

  The guide rail 43 is disposed on the upstream side in the recording sheet conveyance direction. The guide rail 43 has a flat plate shape in which the length in the width direction (the left-right direction in FIG. 3) of the sheet conveyance path 23 is longer than the reciprocation range of the carriage 38. On the other hand, the guide rail 44 is disposed on the downstream side in the conveyance direction of the recording paper. The guide rail 44 has a flat plate shape in which the length in the width direction of the paper transport path 23 is substantially the same as that of the guide rail 43. The carriage 38 is disposed so as to straddle the guide rails 43 and 44. Specifically, the end of the carriage 38 on the upstream side in the transport direction is placed on the guide rail 43, and the end of the carriage 38 on the downstream side in the transport direction is placed on the guide rail 44. 44 is arranged to be slidable in the extending direction.

  The edge 45 on the upstream side in the transport direction of the guide rail 44 is bent at a substantially right angle upward. The carriage 38 carried by the guide rails 43 and 44 slidably holds the edge 45. Thus, the carriage 38 is positioned with respect to the recording paper conveyance direction and can slide in a direction orthogonal to the recording paper conveyance direction. That is, the carriage 38 is slidably supported on the guide rails 43 and 44 and reciprocates in a direction orthogonal to the conveyance direction of the recording paper with reference to the edge 45 of the guide rail 44.

  As shown in FIG. 3, a belt drive mechanism 46 (an example of a transmission mechanism according to the present invention) is disposed on the upper surface of the guide rail 44. The belt driving mechanism 46 transmits the driving force from the CR motor 96 (an example of the driving source of the present invention, see FIG. 6) to the carriage 38, and includes a driving pulley 47, a driven pulley 48, and an endless annular belt. 49.

  A drive pulley 47 (an example of the drive pulley of the present invention) and a driven pulley 48 (an example of the driven pulley of the present invention) are provided in the guide rail 44 near both ends in the width direction of the paper transport path 23. The drive pulley 47 is provided at the end on the maintenance mechanism 51 side on the guide rail 44 that is the movement range of the carriage 38, and the driven pulley 48 is provided at the opposite end. The drive pulley 47 and the driven pulley 48 are each provided rotatably on the guide rail 44. An endless annular belt 49 (an example of the winding member of the present invention) is wound between the driving pulley 47 and the driven pulley 48. In addition to the endless annular belt 49, a belt 49 that fixes both ends of the endless belt to the carriage 38 can also be applied. Further, it is possible to use a wire instead of the belt 49.

  An output shaft of a CR motor 96 (see FIG. 6) for moving the carriage 38 is connected to the shaft of the drive pulley 47. The CR motor 96 is a servo motor manufactured so as to be suitable for feedback control.

  The driven pulley 48 is rotatably supported by a pulley holder 54 attached to the guide rail 44. The guide rail 44 is formed with a long hole extending in the longitudinal direction of the guide rail 44 (left-right direction in FIG. 3), that is, in the moving direction of the carriage 38. The pulley holder 54 is supported so as to be slidable in the longitudinal direction with respect to the elongated hole.

  As shown in FIG. 4, on the guide rail 44 in the vicinity of the pulley holder 54, a bracket 55 is erected vertically upward. A coil spring 56 (an example of an urging member of the present invention) is interposed between the bracket 55 and the pulley guide 54. The coil spring 56 is used as a so-called compression coil, and elastically biases the pulley holder 54 in a direction away from the drive pulley 47 (left direction in FIGS. 3 and 4). Therefore, the driven pulley 48 is elastically biased by the coil spring 56 in the direction in which the tension of the belt 49 increases (the left direction in FIGS. 3 and 4). Thereby, a tension corresponding to the urging force of the coil spring 56 is applied to the belt 49.

  When the CR motor 96 is driven to rotate, the driving torque is transmitted to the driving pulley 47, and the driving pulley 47 rotates. Then, the belt 49 rotates between the drive pulley 47 and the driven pulley 48 by the rotation of the drive pulley 47.

  The carriage 38 is connected to a belt 49 on the lower surface side. Specifically, as shown in FIG. 4, a sandwiching portion 58 provided on the lower surface of the carriage 38 is a portion (hereinafter referred to as an “upstream portion”) on the upstream side in the conveyance direction of the belt 49 (upper side in FIGS. 3 and 4). It is connected by holding 49A. Therefore, when the belt 49 moves around, the carriage 38 slides on the guide rails 43 and 44 along the edge 45. For example, with reference to the standby position (home position) set immediately above the maintenance mechanism 51, the carriage 38 moves in the forward direction 61 (the left direction in FIGS. 3 and 4) when the CR motor 96 is rotated forward. When the CR motor 96 is moved in the reverse direction, the carriage 38 moves in the backward direction 62 (right direction in FIGS. 3 and 4). Hereinafter, the movement of the carriage 38 in the forward direction 61 is referred to as “forward movement”, and the movement of the carriage 38 in the backward direction 62 is referred to as “reverse movement”.

  In the present embodiment, as described above, the clamping portion 58 clamps the upstream portion 49 </ b> A of the belt 49. Therefore, during the forward movement of the carriage 38, the drive torque (the pulling force in the forward direction 61) by the CR motor 96 is a downstream portion in the transport direction of the drive pulley 47 and the belt 49 (hereinafter referred to as “downstream portion”). It is transmitted to the carriage 38 through 49B, the driven pulley 48, and the upstream portion 49A. On the other hand, when the carriage 38 moves backward, the driving torque (the pulling force in the backward direction 62) by the CR motor 96 is transmitted to the carriage 38 via the driving pulley 47 and the upstream portion 49A. As described above, when the carriage 38 is reciprocated by the belt driving mechanism 46, the driving torque is transmitted differently depending on the movement direction of the carriage 38.

  By the way, the moving speed of the carriage 38 is feedback-controlled so as to be the same moving speed by the main control unit 100 described later regardless of whether the carriage 38 is moving forward or backward. However, when cogging torque is generated in the CR motor 96 or when the shaft of the drive pulley 47 is eccentric, the specific torque having periodic variability in the drive torque applied from the CR motor 96 to the belt 49. (Hereinafter referred to as “cogging torque or the like”) is superimposed. The cogging torque and the like are transmitted in different manners when the carriage 38 moves forward and backward. As described above, this difference is due to the difference in the manner in which the drive torque is transmitted by the belt 49 between the forward movement and the backward movement. If cogging torque or the like is transmitted more strongly during the backward movement than during the forward movement, a relatively large speed fluctuation occurs in the carriage 38 that moves in the backward direction 62. Of course, if cogging torque or the like is transmitted more strongly during the forward movement than during the backward movement, on the contrary, a relatively large speed fluctuation occurs in the carriage 38 that moves in the backward direction 62. In this way, under the situation where different speed fluctuations occur between the forward movement and the backward movement, the moving direction of the carriage 38 to which ink is ejected when performing image recording in the high image quality printing mode is the speed. If it is set in the direction of large fluctuation, an image of desired quality cannot be obtained. However, in this embodiment, even in such a situation, the ejection control setting process described later by the main control unit 100 is performed, so that the movement direction of the carriage 38 during ink ejection in the high image quality printing mode is optimal. Set to direction. The configuration of the main control unit 100 and the procedure of the discharge control setting process will be described later.

  As shown in FIG. 3, an encoder strip 50 is disposed on the guide rail 44. The encoder strip 50 is in the form of a strip made of a transparent resin. The encoder strip 50 has a pattern in which the light shielding portions and the light transmitting portions are arranged at an equal pitch. A pair of support ribs 33 and 34 are provided at both ends of the guide rail 44 in the width direction (movement direction of the carriage 38). Both ends of the encoder strip 50 are engaged with the support ribs 33 and 34, and are erected along the edge 45.

  An optical sensor 35 that is a transmissive sensor is provided on the upper surface of the carriage 38 at a position corresponding to the encoder strip 50. The optical sensor 35 includes a first photosensor (not shown) for position detection and a second photosensor (not shown) for origin detection. The first photosensor includes two light emitting elements (for example, LEDs) arranged slightly shifted in the moving direction of the carriage 38 and two light receiving elements (for example, photons) arranged corresponding to these light emitting elements. Transistor). The second photosensor includes one light emitting element and one light receiving element. An encoder strip 50 is disposed between a light emitting element and a light receiving element included in each photosensor. As described above, the optical sensor 35 and the encoder strip 50 are arranged to constitute a linear encoder for detecting the position of the carriage 38.

  In the present embodiment, position information indicating the position of the carriage 38 is obtained by the optical sensor 35 reading the pattern of the encoder strip 50. This position information is input (feedback) to an ASIC 107 (see FIG. 6) of the main control unit 100 described later, and the position of the carriage 38 is recognized. In the ASIC 107, the actual speed, acceleration, and moving direction of the carriage 38 are obtained from the input position information.

  As shown in FIG. 3, a maintenance mechanism 51 is disposed in a range where the recording paper does not pass, that is, outside the image recording area by the recording head 39 (see FIG. 2). Specifically, the maintenance mechanism 51 is disposed at the right end of the platen 42 in FIG. The maintenance mechanism 51 prevents the ink in the nozzles 40 of the recording head 39 from drying or removes bubbles and foreign matters from the nozzles 40 by suction. In the present embodiment, the position directly above the maintenance mechanism 51 is set to the standby position (home position) of the carriage 38. Therefore, when image recording is not performed, the carriage 38 stands by at the standby position until an image recording instruction is input.

  As shown in FIG. 2, a pair of conveyance rollers 89 including a conveyance roller 87 and a pinch roller 88 are provided on the upstream side of the image recording unit 24. On the downstream side of the image recording unit 24, a pair of discharge rollers 92 having a discharge roller 90 and a spur 91 provided above the discharge roller 90 is provided. A gear drive mechanism 85 (see FIG. 6) composed of a plurality of gears is connected to the shaft of the transport roller 87. The rotational driving force of the LF motor 95 (see FIG. 6) is transmitted to the shaft of the conveying roller 87 via the gear driving mechanism 85. As a result, the transport roller 87 is rotated at a predetermined rotational speed, and the recording paper is transported through the paper transport path 23. The transport roller 87 and the paper discharge roller 90 are connected by a transmission mechanism such as a gear, and a driving force is transmitted from the transport roller 87 to the paper discharge roller 90 via the transmission mechanism. As a result, the transport roller 87 and the paper discharge roller 90 are driven synchronously.

  An encoder disk 52 is provided on the rotation shaft of the transport roller 87. On the periphery of the encoder disk 52, a pattern in which light shielding portions and light transmitting portions are alternately arranged at an equal pitch is described. An optical sensor 15 (see FIG. 6) is disposed at a position corresponding to the peripheral edge of the encoder disk 52. The periphery of the encoder disk 52 is disposed between the light emitting element and the light receiving element of the optical sensor 15. The encoder disk 52 and the optical sensor 15 constitute a rotary encoder for detecting the rotational position of the transport roller 87. In the present embodiment, the pattern of the encoder disk 52 that rotates together with the transport roller 87 is read by the optical sensor 15. When the optical sensor 15 reads the pattern of the encoder disk 52, rotational position information indicating the rotational position of the transport roller 87 is obtained.

  In the present embodiment, when an image recording instruction is input to the multifunction device 1 and the leading end of the recording area on the recording paper reaches below the recording head 39, the carriage 38 reciprocates from the standby position set at the right end in FIG. The movement is started and image recording by the recording head 39 is executed.

[Main control unit 100]
Next, the main configuration of the main control unit 100 provided in the printer unit 2 will be described with reference to FIG.

  The main control unit 100 controls the overall operation of the printer unit 2, and in addition to drive control of the CR motor 96 and the LF motor 95, ink is ejected in the ink droplet ejection control by the recording head 39 and in the high image quality printing mode. A process for setting the movement direction of the carriage 38 (discharge control setting process) is performed. The discharge control setting process will be described later.

  As shown in FIG. 6, the main control unit 100 mainly includes a CPU 101 that performs various calculations, a ROM 102, a RAM 103 (an example of the storage medium of the present invention), an EEPROM 104, an ASIC (Application Specific Integrated Circuit) 107, and the like. , An interface (I / F) 108, a CR motor driver 110, an LF motor driver 111, and a head driving circuit 113 are connected by a bus 105 or the like. Note that the CPU 101 embodies storage means, first calculation means, second calculation means, third calculation means, fourth calculation means, comparison means, and setting means of the present invention.

  The interface 108 is for receiving an image recording instruction, a print job, or the like output from a host computer (not shown).

  In the ROM 102, in addition to a program for the CPU 101 to control various operations of the printer unit 2, a program for performing discharge control setting processing, and PID constants (proportional gain, integral gain, and Differential gain, etc.) are stored.

  The RAM 103 is used as a storage area for temporarily recording various data used when the CPU 101 executes the various programs described above, or a work area for performing predetermined arithmetic processing. Position information of the carriage 38 obtained from the optical sensor 35 described above, speed information calculated from the position information, and the like are stored in the RAM 103.

  The EEPROM 104 stores data, setting flags, and the like that should be retained even after the power is turned off. For example, a lookup table for converting RGB data included in a print job input via the interface 108 into CMY data, a speed profile used for PID control, and the like are stored. The look-up table includes a first conversion table (first conversion information of the present invention) used when ink is ejected when the carriage 38 moves forward, and when ink is ejected when the carriage 38 moves backward. A second conversion table to be used (second conversion information of the present invention) is prepared, and these conversion tables are stored in the EEPROM 104 (an example of the conversion information storage means of the present invention).

  The ASIC 107 is configured as a gate array that counts and calculates pulse signals from the optical sensor 35. The ASIC 107 outputs a drive control signal to the CR motor driver 110 under the control of the CPU 101, and outputs position information and speed information of the carriage 38 to the CPU 101. The detailed configuration of the ASIC 107 will be described later.

  The CPU 101 stores a print job received from a host computer (not shown) via the interface 108 in a predetermined storage area of the RAM 103 and performs various arithmetic processes according to a control program stored in the ROM 102 in advance. For example, the RGB image data included in the print job is processed and converted into CMY data that can be actually recorded, and control signals for driving the recording head 39 are sent to the head drive circuit 113. Perform output processing. In response to the position information and speed information from the ASIC 107, a head drive signal is sent to the head drive circuit 113 in synchronization with the movement of the CR motor 96, or via the LF motor driver 111 in accordance with the movement of the CR motor 96. It also plays a role of supervising the operation of each part such as rotating the LF motor 95. The image conversion process will be described later.

  The head drive circuit 113 controls the ejection timing and ejection amount of ink by the recording head 39 based on the input CMY data. Specifically, ink is ejected toward the recording paper by controlling the ejection timing and the ejection amount by applying a control voltage to a piezoelectric element (not shown) provided in the recording head 39.

  The head drive circuit 113 is provided with an internal memory 114. The internal memory 114 stores two control programs used in the high quality print mode. Specifically, the first discharge control for performing the first discharge control (an example of the first control of the present invention) for discharging ink droplets from the nozzles 40 when the carriage 38 moves forward (when moving in the forward direction 61). A second ejection control program for performing a program and second ejection control (an example of the second control of the present invention) for ejecting ink droplets from the nozzles 40 when the carriage 38 moves backward (when moving in the backward direction 62) And are stored. The head drive circuit 113 receives an instruction from the CPU 101, selects any control program stored in the internal memory 114, and performs ink droplet ejection control according to the selected control program.

  The LF motor 95 is a DC motor. The rotary position of the LF motor 95 is detected by a rotary encoder configured by the encoder disk 52 and the optical sensor 15 (see FIG. 6) attached to the rotation shaft of the transport roller 87, and the detection result is input to the ASIC 107. Based on the detection result, a PWM signal for accurately controlling the LF motor 95 is generated in the ASIC 107 so that the conveyance amount of the recording sheet by the conveyance roller 87 becomes a predetermined amount, and the PWM signal is transmitted to the LF motor driver 111. input. The LF motor driver 111 outputs a current corresponding to the input PWM signal to the LF motor 95. The output current flows to the LF motor 95, whereby the transport roller 87 is driven as desired.

  Due to the rotation of the LF motor 95, the driving force is transmitted to the transport roller 87 and the paper discharge roller 90 through a transmission mechanism such as a gear, so that the recording paper is transported. The transport position of the transported recording paper is detected by a sheet sensor (not shown) disposed in the paper transport path 23, and this detection signal is sent to the CPU 101. Upon receiving this signal, the CPU 101 determines the state of the recording paper, and drives or stops the LF motor 95 via the ASIC 107 and the LF motor driver 111.

[ASIC107]
Next, the configuration of the ASIC 107 will be described in detail with reference to FIG. In FIG. 7, the control system related to the LF motor 95 is omitted, and the control related to the LF motor 95 is omitted in the following description.

  The ASIC 107 includes an edge detection unit 121, a carriage position management unit 122, an encoder period measurement unit 123 (an example of the first acquisition unit and the second acquisition unit of the present invention), a PID calculation unit 124, and a PWM generation unit 125. Have Each of these units is configured as a hard logic circuit in which elements such as transistors and capacitors are integratedly arranged, and the circuit is designed so as to realize a specific function described later that each unit has.

  The edge detector 121 detects the edges (rising edges) of the encoder signals ENC1 and ENC2 generated by the optical sensor 35, and generates a reference pulse at the detection timing. The generated reference pulse is output to the carriage position management unit 122 and the encoder cycle measurement unit 123. Further, the edge detection unit 121 obtains the traveling direction of the carriage 38 from the phase difference between the two types of encoder signals ENC1 and ENC2, and outputs a direction flag signal having the direction as a flag to the carriage position management unit 122.

  The carriage position management unit 122 increments the pulse signal based on the direction flag signal and the reference pulse input from the edge detection unit 121 to obtain the position and moving direction of the carriage 38. The position and moving direction of the carriage 38 obtained here are output to the CPU 101, and the CPU 101 recognizes the position and moving direction.

  The encoder period measurement unit 123 obtains the speed of the carriage 38. Specifically, the encoder period measurement unit 123 obtains the speed of the carriage 38 by counting the reference pulses output from the edge detection unit 121 within a predetermined time given by a reference timer (not shown). The obtained speed information is output to the PID calculation unit 124 and stored in the RAM 103 by the CPU 101. The encoder cycle measurement unit 123 measures the moving speed of the carriage 38 in real time in the entire moving range of the carriage 38 as well as the instantaneous speed of the carriage 38 at a predetermined time. Here, the trajectory indicating the transition of the moving speed measured in real time in the entire moving range is referred to as a speed characteristic. In the present embodiment, the speed characteristics (see FIG. 10) at the time of forward movement and reverse movement obtained during the discharge control setting process described later are stored in the RAM 103. Here, the speed characteristic at the time of forward movement corresponds to the first speed characteristic of the present invention, and the speed characteristic at the time of backward movement corresponds to the second speed characteristic of the present invention.

  The PID calculation unit 124 calculates PID control for speed control of the carriage 38 and generates a control signal to be output to the PWM generation unit 125. The PID calculation unit 124 is provided with information related to the PID constants stored in the ROM 102 and the speed profile stored in the EEPROM 104 from the CPU 101. In the PID calculation unit 124, a deviation (speed difference) ΔV between the actual speed (actual speed) of the carriage 38 input from the encoder period measurement unit 123 and the target speed specified by the speed profile is obtained. Then, PID control is calculated using the PID constant, a control signal corresponding to the obtained deviation ΔV is generated, and output to the PWM generator 125.

  The PWM generation unit 125 generates a control signal from the PID calculation unit 124 and a PWM (Pulse Width Modulation) signal corresponding to the CPU 101. The PWM generation unit 125 obtains a predetermined duty ratio (a ratio of the ON time and the OFF time, which is expressed as a ratio of the ON time to a certain period) based on the control signal from the PID calculation unit 124. . Then, a PWM signal having this duty ratio is generated. The generated PWM signal is output to the CR motor driver 110. Upon receipt of the PWM signal, the CR motor driver 110 applies a drive current corresponding to the PWM signal to the CR motor 96 to rotate the CR motor 96. The rotational driving force of the CR motor 96 is transmitted to the carriage 38 via the belt driving mechanism 46. As a result, the carriage 38 moves in a predetermined direction at a predetermined speed.

  Hereinafter, the discharge control setting process executed by the main control unit 100 will be described with reference to the flowchart of FIG. The discharge control setting process is started from step S10.

  First, the CPU 101 determines whether the print mode of the printer unit 2 is set to the high image quality print mode (S10). For example, when a print mode setting flag is set in a register provided in the CPU 101, the determination in step S10 is made based on the state of the setting flag.

  If it is determined in step S10 that the high-quality print mode has been set (S10: Yes), then the carriage 38 is test-driven by one reciprocating movement according to a test program stored in advance in the ROM 102 (S20). During this test drive, the encoder period measurement unit 123 obtains the speed characteristics when the carriage 38 is moving forward and the speed characteristics when the carriage 38 is returning (S30). That is, the encoder period measurement unit 123 acquires the speed characteristic during forward movement and the speed characteristic during backward movement. The acquired speed characteristic is stored (stored) in the RAM 103 by the CPU 101. Thereafter, the CPU 101 counts the number of times the test drive has been performed (S40).

  In the next step S50, it is determined whether or not the count value counted in step S40 is smaller than a predetermined threshold value β (where β is a positive integer). This determination is made as to whether or not the test drive has been performed β times, in other words, whether or not the speed characteristic during the reciprocating motion has been acquired β times. The threshold value β can be set to any numerical value as long as it is a positive integer. Here, if the threshold value β is set to a small value, the time required until the discharge control setting process is completed can be shortened, but the reliability of the deviation amount described later is lowered. On the other hand, if the threshold value β is set to a large numerical value, the reliability of the deviation amount described later increases, but the time required to complete the process becomes longer. In the present embodiment, the threshold value β is set to “5 (times)” in consideration of conflicting circumstances such as the reliability of the deviation amount and the reduction of the processing time.

  When it is determined in step S50 that the count value is smaller than the threshold value β (S50: Yes), the process is repeated according to the procedure from steps S20 to S50. On the other hand, when the count value is larger than the threshold value β (S50: No), the process proceeds to the next step S60. In the present embodiment, since the threshold value β is set to “5 (times)”, the procedure from steps S20 to S50 is repeated five times. As a result, as shown in FIG. 10, the RAM 103 stores five speed characteristics Vf [1] to Vf [5] at the time of forward movement, and five speed characteristics Vr [1] to Vr at the time of backward movement. [5] is stored. FIG. 10 shows the variation characteristics of the actual moving speed (actual speed) Vc of the carriage 38 when the target moving speed Vs required in the constant speed control region of the carriage 38 is used as a reference. In the figure, the vertical axis represents the ratio (Vc / Vs) of the actual speed Vc to the target moving speed Vs, and the horizontal axis represents time.

  As shown in FIG. 10, due to cogging of the CR motor 96, eccentricity of the drive pulley 47, and the like, the actual speed Vc of the carriage 38 is not constant but slightly fluctuates with respect to the target moving speed Vs. The speed fluctuation at the time of forward movement of the carriage 38 and the speed fluctuation at the time of backward movement do not necessarily match. In the present embodiment, as shown in FIG. 10, it is assumed that the speed fluctuation at the time of backward movement is smaller than the speed fluctuation at the time of forward movement.

  By the way, as shown in FIG. 12, the flying distance D in the horizontal direction (moving direction of the carriage 38) from the ejection point H of the ink droplet ejected from the nozzle 40 to the landing point (corresponding to the set position of the present invention) is Using the carriage actual speed Vc, the ink droplet ejection speed Vd, and the distance L from the nozzle 40 to the recording paper P, it is approximately expressed by the following equation (1). Here, the discharge point H is a point when the position of the ink droplet when the ink droplet is discharged from the nozzle 40 is projected onto the recording paper P, and the ink droplet discharge speed Vd moves. This is the initial velocity of ink droplets ejected vertically downward from the nozzle 40 in a coordinate system with the carriage 38 as a reference.

  D≈L · Vc / <Vd> (1)

  Note that <Vd> in Equation (1) is an average of the speeds in the ejection direction, assuming that the ink droplets are decelerated by α per unit distance in the ejection direction due to air resistance. Assuming that after the ink droplets are discharged, the speed in the ink droplet discharging direction upon landing is (Vd−α · L). Therefore, the average value <Vd> of the velocity in the ejection direction of the ink droplet is given by the following equation (2). Equation (1) approximately represents the flight distance D under such conditions.

  <Vd> = Vd−α · L / 2 (2)

  Therefore, in the printer unit 2, when the moving speed Vc of the carriage 38 changes, the flight distance D also changes under the influence. However, the recording head 39 expresses a color image on the recording paper P with magenta, cyan, yellow, and black inks. For this reason, if the flying distance D varies, the ink droplets of each color cannot be landed on the scheduled point (the landing point of the ink droplet when the carriage 38 moves at the target moving speed Vs), and the image quality deteriorates.

  As shown in FIG. 13, when forming a color image in a certain area G on the recording paper P, it is necessary to eject ink droplets of each color toward the area G. In the recording head 39, magenta The positions of the nozzle rows 40M, 40C, 40Y, and 40Bk for cyan, yellow, and black are shifted in the movement direction of the carriage 38, so that it is necessary to eject ink droplets of each color toward the region G at different timings. On the other hand, in the present embodiment, on the assumption that the carriage 38 is moving at the target moving speed Vs, the nozzle rows that have reached the point (discharge point) before the predetermined distance according to the target moving speed Vs from the region G are sequentially ordered. Ink droplets are ejected.

  Therefore, as shown in FIG. 13, under the situation where the actual speed of the carriage 38 is fluctuating, for example, the actual speed when ejecting yellow ink droplets is ΔVc relative to the actual speed when ejecting magenta ink drops. When the number of ink droplets has decreased, the yellow ink droplets land before the landing point of the magenta ink droplets. That is, a deviation of ΔD (= Dm−Dy) occurs between the landing point of the yellow ink droplet and the landing point of the magenta ink droplet. In this case, the color is not properly expressed. If there is a difference in speed fluctuation between the forward movement and the backward movement of the carriage 38 as in this embodiment, it goes without saying that the difference between the deviation amount ΔDf during the forward movement and the deviation amount ΔDr during the backward movement. There is also a difference. Therefore, when the high-quality print mode is set in the printer unit 2, in order to obtain a high-quality image, ejection control for ejecting ink droplets when the carriage 38 moves in the direction of the smaller deviation amount ΔD. Is preferably performed.

  In the present embodiment, the flight distance D is accurately calculated by performing the processing in accordance with the procedure after step S60 in FIG. 8, and the deviation amount ΔD during forward movement and backward movement is appropriately evaluated. Then, a process of setting the ink discharge control in the high image quality printing mode to either the first discharge control for discharging in the forward movement or the second discharge control for discharging in the backward movement is performed. Hereinafter, the procedure after step S60 will be described.

  First, in step S <b> 60, the CPU 101 calculates the actual speed of the carriage 38 when the nozzle row reaches the discharge point H. Thus, the velocity Vc of the component in the horizontal direction (movement direction of the carriage 38) of the ink droplet when it is assumed that the ink droplet is ejected at the ejection point H is obtained as a predicted value. Such calculation processing is performed for each of the forward movement and the backward movement based on the speed characteristics (see FIG. 10) stored in the RAM 103. That is, in step S60, the speed Vc when the nozzle row reaches the discharge point H during the forward movement is obtained, and the speed Vc when the nozzle row reaches the discharge point H during the backward movement is obtained.

  In this embodiment, the speed Vfmc (corresponding to the first speed of the present invention) corresponding to the first timing (corresponding to the first timing of the present invention) when the magenta nozzle row 40M reaches the discharge point H during the forward movement, and The speed Vfyc (corresponding to the second speed of the present invention) corresponding to the second timing (corresponding to the second timing of the present invention) when the yellow nozzle row 40Y reaches the discharge point H is determined from the speed characteristic Vf (see FIG. 10). Extracted. Further, the speed Vrmc corresponding to the third timing (corresponding to the third timing of the present invention) when the magenta nozzle row 40M reaches the discharge point H during the backward movement, and the yellow nozzle row 40Y at the discharge point H during the backward movement. A speed Vryc corresponding to the reached fourth timing (corresponding to the fourth timing of the present invention) is extracted from the speed characteristic Vr (see FIG. 10). In the present embodiment, attention is paid to magenta and yellow having high color discrimination from the viewpoint of improving the image quality, and the color ink is arranged most distant from the viewpoint of highly reliable evaluation value calculation based on the nozzle arrangement. Focusing on magenta and yellow, the velocity Vc was determined for the magenta and yellow nozzle rows 40M and 40Y. Of course, the velocity Vc of each of a plurality of nozzle rows in other combinations may be obtained.

  The RAM 103 stores five speed characteristics Vf [1] to Vf [5] at the time of forward movement, and stores five speed characteristics Vr [1] to Vr [5] at the time of backward movement. Therefore, the velocity Vc of the horizontal component of the ink droplet is obtained for each velocity characteristic.

  In the next step S70, the flying distance Dfm of the magenta ink droplet and the flying distance Dfy of the yellow ink droplet at the time of forward movement are calculated based on the speed calculated in step S60 and the equation (1). The distance difference between the flying distances Dfm and Dfy is calculated by the CPU 101 as the flying distance deviation amount ΔDf (= Dfm−Dfy). Further, the flying distance Drm of the magenta ink droplet and the flying distance Dry of the yellow ink droplet during the backward movement are calculated, and the distance difference between the calculated flying distance Drm and Dry is a deviation amount ΔDr (= Drm−Dry). As calculated by the CPU 101. Also in step S70, five deviation amounts ΔDf [1] to ΔDf [5] are calculated during forward movement, and five deviation amounts ΔDr [1] to ΔDr [5] are calculated during backward movement.

  In step S60, for ease of explanation, the actual speed Vc is calculated only at the first timing and the second timing at the time of forward movement, and the carriage at only the third timing and the fourth timing at the time of backward movement. Although the actual speed Vc of 38 is calculated, in this embodiment, the actual speed Vc is calculated a plurality of times for each predetermined sampling time while the carriage 38 is moving. FIG. 11 shows the deviation amounts ΔDf and ΔDr at the time of forward movement and backward movement obtained based on the speed thus calculated for each sampling time. In the present embodiment, since it is assumed that the speed fluctuation during the backward movement is smaller than the speed fluctuation during the forward movement, the deviation amount ΔDr during the backward movement is larger than the deviation amount ΔDf during the backward movement in FIG. Is smaller.

  In step S80, the CPU 101 performs absolute value summation for each of the five deviation amounts ΔDf [1] to ΔDf [5] during forward movement. Further, absolute values are summed for each of the five deviation amounts ΔDr [1] to ΔDr [5] during the backward movement. Specifically, the deviation ΔDf [1] during forward movement will be described in detail. The absolute values | ΔDf [1] | of all deviations ΔDf [1] obtained every predetermined sampling time are added. Thus, the evaluation value Ef [1] is calculated. Further, the deviation amount ΔDr [1] at the time of forward movement will be described in detail. The absolute value | ΔDr [1] | of all the deviation amounts ΔDr [1] obtained every predetermined sampling time is added and evaluated. Er [1] is calculated. Such calculation processing is individually performed for each of the deviation amounts ΔDf [1] to ΔDf [5] at the time of forward movement, and the evaluation values Ef [1] to Ef [5] (the first evaluation value of the present invention). Equivalent) is calculated. Further, the deviation amounts ΔDr [1] to ΔDr [5] at the time of backward movement are individually performed, and evaluation values Er [1] to Er [5] (corresponding to the second evaluation value of the present invention) are calculated. The Table 1 shows the calculated evaluation values.

  In addition, when the calculation process performed in step S80 is expressed by a general formula, it is expressed as the following formula (3). In addition, the symbol N in Formula (3) shows the number of data, and the symbol t shows the count value for every sampling time.

  In the next step S90, the CPU 101 performs an averaging process of the evaluation values calculated in step S80. That is, processing for calculating the arithmetic average value of the evaluation values calculated in step S80 is performed. Specifically, an average value <Ef> of five evaluation values Ef [1] to Ef [5] at the time of forward movement is obtained, and five evaluation values Er [1] to Er [5] at the time of backward movement are obtained. An average value <Er> is obtained (see Table 1).

  Subsequently, the average value <Ef> and the average value <Er> are compared (S100). Specifically, the CPU 01 determines whether or not the average value <Ef> is greater than or equal to the average value <Er>. If it is determined that the average value <Ef> is equal to or greater than the average value <Er> (S100: Yes), the first discharge control is set as the ink discharge control during image recording (S110). On the other hand, when it is determined that the average value <Ef> is less than the average value <Er> (S100: No), the second discharge control is set as the ink discharge control during image recording (S120). The ink discharge control is set by, for example, setting a setting flag corresponding to each of the first discharge control and the second discharge control in a register in the CPU 101.

  Hereinafter, the image conversion process executed by the main control unit 100 will be described with reference to the flowchart of FIG. 9. The image conversion process starts from step S210 on the assumption that the printer unit 2 is set to the high image quality print mode.

  First, the CPU 101 determines whether a print job has been input via the interface 108 (S210). If it is determined that a print job has been input (S210: Yes), in the next step S220, it is determined whether or not the ink discharge control by the recording head 39 is set to the first discharge control. Such a determination is made based on the register setting flag of the CPU 101.

  If it is determined in step S220 that the first discharge control is set (S220: Yes), the CPU 101 reads the first conversion table from the EEPROM 104 (S230). On the other hand, if it is determined in step S220 that the first discharge control is not set, that is, if it is determined that the second discharge control is set (S220: Yes), the CPU 101 performs the second conversion from the EEPROM 104. The table is read (S240).

  Next, according to the conversion table read in step S230 or S240, conversion processing of the image data transmitted together with the print job is executed (S250). In step S250, the RGB image data is converted into CMY data based on the conversion table. The CPU 101 that performs the process of reading the conversion table from the EEPROM 104 and the process of converting the RGB image data into CMY data corresponds to the reading unit and the image conversion unit of the present invention.

  When the conversion process in step S250 ends, the converted CMY data is transferred to the head drive circuit 113. At this time, setting information indicating whether the ink discharge control is set to the first discharge control or the second discharge control is transferred to the head driving circuit 113 together with the CMY data. Upon receiving these data, the head drive circuit 113 reads a control program corresponding to the setting information from the internal memory 114 based on the input setting information, and according to the control program, an image corresponding to the CMY data is read. The recording head 39 is controlled to perform recording.

  As described above, in the above-described embodiment, the flying distance D is accurately calculated, and the average values <Ef> and <Er> of the evaluation values based on the deviation amount ΔD during forward movement and backward movement are compared and determined. Since the ink ejection control in the high image quality printing mode is set by this, it is reliably determined whether the speed fluctuation is small when the carriage 38 moves in the forward direction 61 or the backward direction 62, and the movement with the small speed fluctuation is performed. The control method can be easily set to perform appropriate ink droplet ejection control in the direction. As a result, the quality of the recorded image by the printer unit 2 is improved.

  Further, in this embodiment, the test drive is performed a plurality of times to acquire the speed characteristics, and a plurality of deviation amounts ΔD are obtained for each sampling time, and the evaluation value is calculated based on this, so that the evaluation value is calculated. The reliability of the value itself is increased, so that an erroneous setting of ink ejection control is prevented.

  Moreover, in this embodiment, since the comparison determination of step S100 is performed using the average value <E> of the plurality of evaluation values E [1] to E [5], the accuracy of the comparison determination process is stabilized.

  In this embodiment, the average values <Ef> and <Er> of the evaluation values are obtained and compared based on the magenta and yellow nozzle rows 40M and 40Y having good color discrimination characteristics, and then the ink ejection is performed. Control is set. Therefore, the image quality of the color image actually recorded on the recording paper can be maintained at high quality.

  Further, in this embodiment, the average value <Ef>, the average value <Ef> of the evaluation values, based on the magenta nozzle row 40M and the yellow nozzle row 40Y, which are expected to have the largest deviation amount of the ink droplet landing position. Since <Er> is calculated, the reliability of the evaluation value itself can be increased, and as a result, the image quality of the color image recorded on the recording paper can be maintained at a high quality.

  In the above-described embodiment, a plurality of speed characteristics are acquired for each of the forward movement and the backward movement, and the deviation amount ΔD and the evaluation value E are obtained for each speed characteristic. A plurality of speed characteristics may be averaged, the plurality of speed characteristics at the time of reverse movement may be averaged, and the deviation amount ΔD and the evaluation value E may be obtained based on the averaged average speed characteristics.

  In the above-described embodiment, the ejection control setting process is performed when the print mode of the printer unit 2 is set to the high image quality print mode. For example, the timing when a predetermined time elapses, or The discharge control setting process may be started at the timing when the main power is turned on to the multifunction machine 1.

FIG. 1 is a perspective view showing an external configuration of the multifunction machine 1. FIG. 2 is a partially enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 3 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. FIG. 4 is a schematic diagram schematically showing the outline of the configuration of the belt drive mechanism 46. FIG. 5 is a bottom view showing the nozzle formation surface of the recording head 39. FIG. 6 is a block diagram illustrating a main configuration of the main control unit 100 of the printer unit 2. FIG. 7 is a block diagram showing the configuration of the ASIC 107 in detail. FIG. 8 is a flowchart illustrating an example of the procedure of the discharge control setting process for setting the discharge control by the recording head 39. FIG. 9 is a flowchart illustrating an example of a procedure of image conversion processing using a conversion table. FIG. 10 is a diagram showing speed characteristics Vf and Vr during reciprocating motion. FIG. 11 is a diagram illustrating the deviation amounts ΔDf and ΔDr during the reciprocating motion for each sampling time. FIG. 11 is a diagram illustrating the deviation amounts ΔDf and ΔDr during the reciprocating motion for each sampling time. FIG. 12 is a diagram for explaining the horizontal flight distance D from the discharge point H to the landing point. FIG. 13 is a diagram for explaining the deviation amount ΔD of the landing point of the ink droplet due to the speed fluctuation on the carriage 38.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MFP 2 ... Printer part 35 ... Optical sensor 38 ... Carriage 50 ... Encoder strip 95 ... LF motor 96 ... CR motor 100 ... Main control part 101- ..CPU
102 ... ROM
103 ... RAM
104 ... EEPROM
107: Motor control unit (control unit)
110 ... CR motor driver 111 ... LF motor driver 113 ... head drive circuit 121 ... edge detection unit 122 ... carriage position management unit 123 ... encoder period measurement unit 124 ... PID calculation Unit 125... PWM generation unit

Claims (11)

A carriage that receives a driving force from a driving source and reciprocates in a predetermined direction;
A recording head mounted on the carriage and having a first nozzle and a second nozzle separated in a moving direction of the carriage, and ejecting ink droplets from each nozzle;
First acquisition means for acquiring a first speed characteristic of the carriage during forward movement;
Second acquisition means for acquiring a second speed characteristic of the carriage during backward movement;
Storage means for storing the first speed characteristic and the second speed characteristic acquired by the first acquisition means and the second acquisition means in a storage medium;
Based on the first speed characteristic, a first speed of the carriage corresponding to a first timing for ejecting ink droplets from the first nozzle to a predetermined setting position is obtained, and the setting is made from the second nozzle. First computing means for obtaining a second speed of the carriage corresponding to a second timing for ejecting ink droplets to a position;
Second computing means for obtaining a first evaluation value based on a difference between the first speed and the second speed obtained by the first computing means;
Based on the second speed characteristic, a third speed of the carriage corresponding to a third timing for ejecting ink droplets from the first nozzle to the set position is obtained, and ink is transferred from the second nozzle to the set position. Third computing means for obtaining a fourth speed of the carriage corresponding to a fourth timing for ejecting droplets;
Fourth computing means for obtaining a second evaluation value based on a difference between the third speed and the fourth speed obtained by the third computing means;
Comparing means for comparing the first evaluation value obtained by the second computing means with the second evaluation value obtained by the fourth computing means;
Based on the comparison result by the comparison means, the ink droplet ejection control at the time of image recording is the first control in which ink droplets are ejected from the nozzles when the carriage moves in the forward direction, or the carriages move in the backward direction. An image recording apparatus comprising: setting means for setting to any one of the second control for ejecting ink droplets from the nozzles. In the case where a plurality of the above setting positions are determined,
The first calculating means obtains the first speed at each of a plurality of first timings for ejecting ink droplets to a plurality of set positions, and ejects ink droplets from the second nozzle to the plurality of set positions, respectively. To obtain the second speed for each of a plurality of second timings,
The second calculation means has a plurality of first evaluation values based on a difference between the first speed and the second speed corresponding to the same set position obtained by the first calculation means for each of the plurality of setting positions. Is what
The third calculating means obtains the third speed at each of a plurality of third timings for ejecting ink droplets to the plurality of setting positions, and applies ink droplets from the second nozzle to the plurality of setting positions. Determining the fourth speed for each of a plurality of fourth timings for discharging;
The fourth calculation means has a plurality of second evaluation values based on a difference between the third speed and the fourth speed corresponding to the same setting position obtained by the third calculation means for each of the plurality of setting positions. The image recording apparatus according to claim 1, wherein: The first acquisition means acquires the first speed characteristic for each of a plurality of forward movements,
The second acquisition means acquires the second speed characteristic for each of a plurality of backward movements.
The second calculation means obtains a plurality of first evaluation values based on a difference between the first speed and the second speed obtained by the first calculation means for each of the plurality of first speed characteristics. , And average the plurality of first evaluation values,
The fourth computing means obtains a plurality of second evaluation values based on a difference between the third speed and the fourth speed obtained by the third computing means for each of the plurality of second speed characteristics. The image recording apparatus according to claim 1, wherein the plurality of second evaluation values are averaged. The first acquisition means acquires the first speed characteristic for each of a plurality of forward movements,
The second acquisition means acquires the second speed characteristic for each of a plurality of backward movements.
The storage means averages the plurality of first speed characteristics acquired by the first acquisition means, averages the plurality of second speed characteristics acquired by the second acquisition means, and stores them in the storage medium. Is what
The first calculation means obtains the first speed and the second speed based on the averaged first speed characteristic stored in the storage medium,
3. The image recording according to claim 1, wherein the third calculation means obtains the third speed and the fourth speed based on the averaged second speed characteristic stored in the storage medium. apparatus. The first evaluation value is obtained based on the first speed, and a separation distance from a first predicted landing position of the ink droplet ejected from the first nozzle at the first timing to the set position, and the first 2 is a difference between a separation distance from a second predicted landing position of the ink droplet ejected from the second nozzle at the second timing to the set position, obtained based on two speeds;
The second evaluation value is obtained based on the third speed, and the separation distance from the third predicted landing position of the ink droplet ejected from the first nozzle at the third timing to the set position, and the second 5. The difference between the fourth predicted landing position of the ink droplets ejected from the second nozzle at the third timing and the set position, which is obtained based on three speeds. 6. The image recording apparatus described in 1.   The comparison means compares the average value of the plurality of first evaluation values obtained by the second calculation means with the average value of the plurality of second evaluation values obtained by the fourth calculation means. The image recording apparatus according to claim 2. First conversion information corresponding to the first control and second conversion information corresponding to the second control, which is used when converting the image data input to the image recording apparatus into data of a predetermined format capable of image recording. Conversion information storage means storing
Reading means for reading out conversion information from the conversion information storage means according to the ink droplet ejection control set by the setting means;
The image recording apparatus according to claim 1, further comprising image conversion means for converting the image data based on the conversion information read by the reading means. A transmission mechanism for transmitting the driving force from the driving source to the carriage;
The transmission mechanism is
A driving pulley rotatably provided at one end of the carriage movement range and connected to the output shaft of the driving source;
A driven pulley that is rotatably provided at the other end of the carriage movement range and is slidably supported in the carriage movement direction;
A winding member wound around the drive pulley and the driven pulley;
The image recording apparatus according to claim 1, further comprising an urging member that urges the driven pulley in a direction in which the tension of the winding member increases.   9. The image recording according to claim 1, wherein the first nozzle is for ejecting magenta ink, and the second nozzle is for ejecting yellow ink. 10. apparatus. The recording head further includes a third nozzle from which ink droplets are ejected,
10. The image recording apparatus according to claim 1, wherein the first nozzle and the second nozzle are arranged in a moving direction of the carriage with the third nozzle interposed therebetween. Image recording comprising a carriage capable of reciprocating in a predetermined direction by receiving a driving force from a driving source, and a recording head mounted on the carriage and having a first nozzle and a second nozzle separated in the moving direction of the carriage An ejection control setting method that is applied to an apparatus and sets ink droplet ejection control for ejecting ink droplets from each nozzle.
A first acquisition step of acquiring a first speed characteristic of the carriage during forward movement;
A second acquisition step of acquiring a second speed characteristic of the carriage during backward movement;
A storage step of storing the first speed characteristic and the second speed characteristic acquired in the first acquisition step and the second acquisition step in a storage medium;
Based on the first speed characteristic, a first speed of the carriage corresponding to a first timing for ejecting ink droplets from the first nozzle to one or more predetermined setting positions is obtained, and the first speed is obtained. A first calculation step for obtaining a second speed of the carriage corresponding to a second timing for ejecting ink droplets from two nozzles to the set position;
A second calculation step for obtaining a first evaluation value based on a difference between the first speed and the second speed obtained by the first calculation step;
Based on the second speed characteristic, a third speed of the carriage corresponding to a third timing for ejecting ink droplets from the first nozzle to the set position is obtained, and ink is transferred from the second nozzle to the set position. A third calculation step for obtaining a fourth speed of the carriage corresponding to a fourth timing for ejecting droplets;
A fourth computation step for obtaining a second evaluation value based on a difference between the third speed and the fourth speed obtained by the third computation step;
A comparison step for comparing the first evaluation value obtained by the second calculation step with the second evaluation value obtained by the fourth calculation step;
Based on the comparison result in the comparison step, the ink droplet ejection control at the time of image recording is the first control in which ink droplets are ejected from the nozzles when the carriage moves in the forward direction, or A setting step of setting to any one of the second control for discharging ink droplets from the nozzles.

Images