JP2006159779A - Inkjet recording apparatus and recording positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent recording image quality at all the inter-paper positions from deteriorating while burden of a user is reduced. <P>SOLUTION: An inter-paper distance which is a distance between a delivering face of a recording head and a recording medium, is set at one among a plurality of them (S201 and S205). In accordance with a driving condition of the recording head, a pattern for positioning of recording is recorded on the recording medium. Optical characteristics of the pattern recorded are measured, and based on the result of the measurement, an alignment on corresponding inter-paper distance is adjusted (S202), and adjustments of the alignments on all the inter-paper distances are practiced by repeating these processings. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet recording apparatus and a recording alignment method, and more specifically, recording on a recording medium by an inkjet recording head that ejects ink, and a paper that is a distance between an ejection surface of the recording head and the recording medium The present invention relates to printing position alignment in an ink jet printing apparatus having a paper gap setting means for setting the gap distance to one of a plurality.

  In recent years, with the widespread use of personal computers and digital cameras, various recording devices that print out information output from these devices, high-speed technology for the devices, and high image quality technology have been rapidly developed. Among the recording apparatuses, a serial type printer using a dot matrix recording method has attracted attention as a recording apparatus that realizes high-quality recording at low cost and high speed. As a technology for performing high-speed recording with respect to such a printer, for example, there is bidirectional recording, and as a technology for performing high-quality recording, for example, there is a multipass recording method.

  In the dot matrix recording method, a high-quality image cannot be obtained unless the dot landing position is adjusted and ink is landed at a predetermined position. Therefore, dot alignment that adjusts the landing position of the dots is necessary. Dot alignment is a method of adjusting the position at which dots are formed on a recording medium by some means, and is more commonly called recording position alignment.

  In the conventional dot alignment processing, for example, in the landing position alignment of the forward scanning and the backward scanning in bidirectional recording, by adjusting the recording timing of each of the forward scanning and the backward scanning, the reciprocating scanning in both directions is possible. The ruled lines and the like are printed on the recording medium while changing the relative recording position conditions. Whether the user visually observes it, selects the condition that seems to be in the best position, that is, the condition that the ruled line is printed without being shifted, and is set by inputting directly to the recording device by key operation etc. Alternatively, the landing position condition is set in the recording apparatus via the application by operating the host computer.

  In addition, a pattern corresponding to a plurality of shift amounts of relative recording positions of the first print and the second print (recording in the forward scanning and the backward scanning, or recording by different recording heads, respectively) is recorded. Using an optical sensor composed of a light emitting part (generally an LED) and a light receiving part (generally a phototransistor), optical characteristics such as reflection density are measured for each pattern, and the result is used to Japanese Patent Laid-Open No. 10-329381 (Patent Document 1) discloses a technique for determining a recording position alignment (dot alignment) condition between the first and second prints.

  In addition, the ink jet recording apparatus is characterized in that recording can be performed on various recording media such as plain paper, special paper, envelopes, and CD-Rs. However, generally, there is a possibility that the recording medium and the recording head may be rubbed (contacted) by a so-called cockling phenomenon of the recording medium due to ink ejection, so that a high-quality image may not be obtained. . Therefore, in each recording medium, it is necessary to adjust the distance between the recording medium and the ejection surface of the recording head (hereinafter, referred to as the inter-paper or inter-paper distance, and the position is referred to as the inter-paper position). In other words, when recording on a thick recording medium such as thick paper or an envelope, if recording is performed between ordinary papers that are recorded on a recording medium such as plain paper, the recording head and the recording medium will be rubbed. It is necessary to set the paper gap larger than the paper gap so that the recording head and the recording medium are not rubbed.

  In general, the ink droplets ejected from the recording head can be landed at a more accurate position by reducing the flight distance. Basically, in special paper (coated paper) with high ink absorption capability, rubbing due to the cockling described above is difficult to occur, so the paper gap can be set smaller than that between plain paper, High quality recording with little landing position deviation can be performed.

  FIG. 7 is a schematic diagram showing the state of ink droplets ejected from the recording head between various papers. As shown in the drawing, the flying distance of the ink droplets ejected from the recording head varies depending on the paper interval, and thus the landing position is shifted. If the ink droplets landed on the recording medium between the papers are A, B, and C, the deviation increases in the order of C → B → A as the paper space increases (a> b). Therefore, in order to reduce this deviation, it is necessary to adjust the dot position according to the gap between sheets.

  Therefore, the dot position adjustment value for the paper interval not subjected to the dot alignment process needs to be corrected so that the landing position is accurate with respect to the dot position adjustment value for the paper interval subjected to the dot alignment process. For example, in a certain ink jet printer, when there is a deviation of two pixels in the dot position adjustment value between the case where the paper interval is large and the case between normal papers, automatic dot alignment processing is performed between the normal papers. By applying correction (for example, correcting for +2 pixels) to the dot position adjustment value when performing the above, a dot position adjustment value corresponding to a case where the paper gap is large is obtained. In this way, for paper intervals that have not been subjected to dot alignment processing, the dot position adjustment value is corrected with a fixed correction value to set the dot position adjustment value, and recording is performed.

Japanese Patent Application Laid-Open No. 11-291553 (Patent Document 2) describes a method for obtaining the maximum value of the reflection optical density from a test pattern by linear approximation using the least square method.
Japanese Patent Laid-Open No. 10-329381 JP 11-291553 A

  As described above, in order to enable high-quality recording on various types of recording media, settings between a plurality of sheets and corresponding dot position adjustment values are required for each recording medium. Therefore, in order to perform high-quality recording between any paper, it is desirable to perform dot alignment processing at each paper position and derive a dot position adjustment value between each paper.

  However, if the dot position adjustment is performed between the respective sheets, there is a problem that time and labor are required and the burden on the user increases. In addition, as in the past, correction may be performed to derive a dot position adjustment value for a sheet interval that has not been subjected to dot alignment processing. However, if a fixed correction value is used, individual devices can be corrected even if correction is performed. There is a possibility that the dot adjustment position will be displaced due to variations in the mounting position and tolerance of the recording head, the nozzle size of the recording head (the size of the ejected ink droplet), the ejection speed, and the like.

  In other words, even if correction is performed with a fixed correction value for the dot position adjustment value derived by performing automatic dot alignment processing with a large paper gap setting, dot position adjustment for the paper gap for recording images with the highest quality is possible. Deviations in value will occur. In particular, in the highest quality mode in which recording is performed using small ink droplets, a deviation in the landing position is visually recognized as a deterioration in image quality, and there is a possibility that high quality recording cannot be performed.

  The present invention has been made in view of the above situation, and an object of the present invention is to prevent deterioration of the recording image quality at all inter-paper positions while reducing the burden on the user.

An inkjet recording apparatus as an aspect of the present invention that achieves the above object is an inkjet recording apparatus that performs recording on a recording medium by an inkjet recording head that ejects ink,
A paper gap setting means for setting a paper gap, which is a distance between the ejection surface of the print head and the print medium, to one of a plurality of settable distances;
Pattern recording means for recording a pattern for recording alignment on the recording medium in correspondence with the driving condition of the recording head;
Measuring means for measuring the optical characteristics of the pattern;
The drive for each inter-paper distance based on the measurement results of the plurality of patterns recorded corresponding to different inter-paper distances by controlling the inter-paper setting means, the pattern recording means, and the measuring means. Alignment means for obtaining information on conditions.

Further, a recording alignment method as another aspect of the present invention that achieves the above object is a recording alignment method in an inkjet recording apparatus that performs recording on a recording medium by an inkjet recording head that ejects ink,
A paper gap setting step of setting a paper gap, which is a distance between the ejection surface of the print head and the print medium, to one of a plurality of settable distances;
A pattern recording step of recording a pattern for recording alignment on the recording medium in accordance with the driving condition of the recording head;
A measuring step for measuring optical characteristics of the pattern;
The driving condition for each inter-paper distance based on the measurement results of the plurality of patterns recorded corresponding to different inter-paper distances by repeating the inter-paper setting step, the pattern recording step, and the measuring unit. And an alignment step for obtaining information on.

  That is, in the present invention, in an ink jet recording apparatus that records on a recording medium by an ink jet recording head that discharges ink, a plurality of paper distances, which are distances between the ejection surface of the recording head and the recording medium, can be set. One of the distances is set, a pattern for recording alignment is recorded on the recording medium in accordance with the driving condition of the recording head, the optical characteristics of the recorded pattern are measured, these settings, recording and The measurement is repeated, and information on driving conditions for each inter-paper distance is obtained based on the results of measurement of a plurality of patterns recorded corresponding to different inter-paper distances.

  In this way, in an ink jet recording apparatus that can set a plurality of inter-paper distances, which are distances between the ejection surface of the recording head and the recording medium, the recording position is adjusted for each inter-paper distance while reducing the burden on the user. Information on the optimum driving conditions is automatically obtained.

  Therefore, it is possible to prevent deterioration of the recording image quality at all the inter-paper positions while reducing the burden on the user.

  The above object can also be achieved by a computer program for realizing the recording position alignment method according to the present invention by a computer device, and a storage medium storing the computer program.

  According to the present invention, in an inkjet recording apparatus capable of setting a plurality of inter-paper distances, which are distances between the ejection surface of the recording head and the recording medium, the recording position is adjusted for each inter-paper distance while reducing the burden on the user. Information on the optimum driving conditions is automatically obtained.

  Therefore, it is possible to prevent deterioration of the recording image quality at all the inter-paper positions while reducing the burden on the user.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the components described in the following embodiments are merely examples, and are not intended to limit the scope of the present invention only to them.

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and figures, but also for human beings visually perceived regardless of significance. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, the term “nozzle” (sometimes referred to as “recording element”) refers to a liquid path communicating with this from an ejection port and elements that generate energy used for ink ejection unless otherwise specified. Say it.

  Here, as the energy used for ejecting the ink, for example, thermal energy that causes film boiling in the ink can be used, and a heating element can be used as the element that generates thermal energy. However, it is not limited to these.

  In this specification, as optical characteristics, optical density, that is, reflection optical density using reflectance and transmission optical density using transmittance are used. However, optical reflectivity, reflected light intensity, etc. can also be used. In this specification, unless otherwise specified, the reflection optical density is abbreviated as optical density or simply density.

(1) Inkjet recording apparatus First, the configuration of an inkjet recording apparatus common to the embodiments according to the present invention will be described with reference to the drawings. Here, a printer (inkjet printer) that performs recording in accordance with an inkjet recording method will be described as an example.

(1-1) Device Main Body FIG. 1 is a schematic perspective view showing the overall configuration of the ink jet printer according to the present invention with the cover removed. FIG. 2 is a schematic sectional side view showing the overall configuration of the recording apparatus as seen from the direction of arrow A in FIG.

  In these drawings, 1 is a recording unit main body, 10 is a chassis that supports the structure of the recording unit main body 1, 11 is a recording head that performs recording by discharging ink, and 12 is an ink tank that stores ink to be supplied to the recording head. , 13 is a carriage for holding and scanning the recording head 11 and the ink tank 12, 14 is a guide shaft for supporting the carriage, 15 is a guide rail for supporting the carriage 13 in parallel with the guide shaft 14, and 16 is for driving the carriage. A carriage belt 17 for driving the carriage belt 16 via a pulley, 18 a code strip provided with graduations for detecting the position of the carriage 13 at predetermined intervals, and 20 a carriage motor 17. An idler that stretches the carriage belt 16 opposite the pulley Is Li.

  Further, 21 is a paper feed roller for conveying the recording paper, 22 is a pinch roller that is driven by the paper feed roller 21, 23 is a pinch roller holder that rotatably holds the pinch roller 22, and 24 is a paper for holding the pinch roller 22 on paper. A pinch roller spring pressed against the feed roller, 25 is a paper feed roller pulley fixed to the paper feed roller, 26 is an LF motor for driving the paper feed roller, and 27 is a scale for detecting the rotation angle of the paper feed roller. A code wheel provided at every predetermined angle, 29 is a platen that supports the recording paper so as to face the recording head 11, 30 is a first paper discharge roller for conveying the recording paper in cooperation with the paper feed roller 21, 31 Is a second paper discharge roller provided on the downstream side of the first paper discharge roller 30, 32 is a first spur train that holds the recording paper facing the first paper discharge roller 30, and 33 is Second spur column to hold the second output rollers opposed to the recording sheet, 34 is a spur base for holding and spinning a first spur row 32 and the second spur train 33.

  Further, 36 is a maintenance unit used for preventing nozzle clogging of the recording head 11 and replacing the ink tank 12, 37 is a main ASF for loading recording sheets and supplying them one by one during recording operation, and 38 is a base of the main ASF 37. ASF base 39, a paper feed roller that contacts and transports the stacked recording paper, 40 is a separation roller that separates the recording paper one by one when it is transported simultaneously, and 41 is a recording paper stack A pressure plate 42 for urging in the direction of the paper feed roller 39 is a side guide that is provided on the pressure plate 41 and can be fixed with an arbitrary recording paper width. The leading edge of the recording paper that has advanced beyond the nip portion between the paper feeding roller 39 and the separation roller 40 during the paper feeding operation is returned to a predetermined position by the return claw.

  Reference numeral 44 denotes an ASF flap for restricting the recording paper passing direction from the main ASF 37 to one direction, 50 denotes a lift input gear that engages with the ASF planetary gear 49, and 51 transmits the power from the lift input gear 50 while decelerating. Lift reduction gear train 52, lift cam gear 52 directly connected to the lift cam shaft, 55 a guide shaft spring for biasing the guide shaft to one side, 56 a guide slope on which the cam of the guide shaft gear 53 slides, 58 A lift cam shaft for lifting the pinch roller holder 23 and the like, 70 is a paper feed guide for guiding the leading edge of the recording paper to the nip portion of the paper feed roller 21 and the pinch roller 22, 72 is a base for supporting the entire recording unit body 1, 301 Is a control board for grouping the control units.

  FIG. 3 is a block diagram showing a control configuration of the entire inkjet printer according to the present invention. In the figure, 19 is a CR encoder sensor mounted on the carriage 13 and reads the code strip 18, 28 is an LF encoder sensor attached to the chassis 10 and reads the code wheel 27, 46 is an ASF motor that drives the main ASF 37, and 67 is PE sensor that detects the operation of the PE sensor lever, 69 is a lift cam sensor that detects the operation of the lift cam shaft 58, 130 is a double-sided unit sensor that detects attachment / detachment of the automatic duplexing unit 2, and 302 is a PG motor that drives the maintenance unit 36. , 303 is a PG sensor that detects the operation of the maintenance unit 36, 305 is an ASF sensor that detects the operation of the main ASF 37, 307 is a head driver that drives the recording head 11, 308 is a host device that sends recording data to the recording apparatus, 309 An intermediary interface (I / F) for electrically connecting the host apparatus and the recording apparatus, 310 a CPU for controlling the printer and issuing a control command, 311 a ROM in which control data is written, and 312 a recording This is a RAM serving as an area for developing data and the like.

  First, the schematic operation of the printer will be described with reference to FIGS. 1 and 2, and then the operation of each unit will be described in detail with reference to the drawings.

  First, an outline of the configuration of a general serial type printer will be described.

  The printer according to the present embodiment is roughly divided into a sheet feeding unit, a sheet conveying unit, a recording unit, and a recording head maintenance unit.

  When recording data is sent from the host device 308 and stored in the RAM 312 via the I / F 309, the CPU 310 issues a recording operation start command to start the recording operation. When the recording operation starts, a paper feeding operation is first performed.

(1-2a) Paper Feed Unit The paper feed unit is a main ASF (Automatic Sheet Feeder) 37, and pulls out one recording sheet for each recording operation from a plurality of recording sheets (not shown) stacked on the pressure plate 41. To send to the paper transport unit. At the start of the paper feeding operation, the ASF motor 46 rotates in the forward direction, and the power rotates the cam holding the pressure plate 41 via the gear train. When the cam is removed by rotation, the pressure plate 41 is urged toward the paper feed roller 39 by the action of a pressure plate spring (not shown). At the same time, the paper feed roller 39 rotates in the direction in which the paper is transported, so that transport of the top recording paper loaded is started.

  At that time, a plurality of recording sheets may be conveyed at the same time depending on the conditions of the frictional force between the sheet feeding roller 39 and the recording sheet and the frictional force between the recording sheets. In that case, a separation roller 40 is pressed against the paper feed roller 39 and has a predetermined return rotational torque in the direction opposite to the recording paper transport direction, and the original paper other than the recording paper closest to the paper feed roller 39 is actuated. It works to push back onto the pressure plate. Further, at the end of the ASF paper feeding operation, the separation roller 40 is released from the pressure contact state with the paper feeding roller 39 by the operation of the cam and is separated by a predetermined distance. At that time, the recording paper is surely reached a predetermined position on the pressure plate. To push back, the return claw rotates and plays its role.

  By the operation as described above, only one recording sheet is conveyed to the sheet conveying unit. When one recording sheet is transported from the main ASF 37, the leading edge of the recording sheet abuts on the ASF flap 44 that is urged by the ASF flap spring in a direction that prevents the sheet passing path. Push away and pass. When the recording operation of the recording sheet is completed and the trailing edge of the recording sheet passes through the ASF flap 44, the ASF flap 44 returns to the original biased state and the sheet passing path is closed, so that the recording sheet is conveyed in the reverse direction. However, it does not return to the main ASF 37 side.

(1-2b) Paper Conveying Unit The recording paper conveyed from the paper feeding unit is conveyed toward the nip portion between the paper feed roller 21 and the pinch roller 22 which are paper conveying units. Since the center of the pinch roller 22 is attached to the center of the paper feed roller 21 with a slight offset in the direction approaching the first paper discharge roller 30, the tangential angle at which the recording paper is inserted is slightly higher than the horizontal. Tilted. Accordingly, the sheet is conveyed at an angle in the sheet passing path formed by the pinch roller holder 23 and the sheet passing guide 70 so that the leading end of the sheet is accurately guided to the nip portion.

  The sheet conveyed by the ASF 37 is abutted against the nip portion between the stopped paper feed roller 21 and the pinch roller 22. At this time, a paper loop is formed between the paper feed roller 39 and the paper feed roller 21 by transporting the main ASF 37 for a distance slightly longer than a predetermined paper feed path length. When the leading edge of the paper is pressed against the nip portion of the paper feed roller 21 with a force that the loop returns straight, the leading edge of the paper becomes parallel to the paper feed roller 21 and the so-called registration operation is completed.

  After the registration removal operation is completed, the LF motor 26 is started to rotate in the direction in which the recording sheet moves in the forward direction (the direction in which the recording sheet advances toward the first paper discharge roller 30). After that, the driving force of the paper feed roller 39 is cut, and the paper feed roller 39 rotates with the recording paper. At this point, the recording paper is conveyed only by the paper feed roller 21 and the pinch roller 22. The paper advances in the positive direction every predetermined line feed amount, and advances along the rib provided on the platen 29. The leading edge of the paper gradually hangs over the first paper discharge roller 30 and the first spur train 32, and the second paper discharge roller 31 and the second spur train 33, but the peripheral speed of the first paper discharge roller 30 and the second paper discharge roller 31 Is set to be approximately equal to the peripheral speed of the paper feed roller 21, and since the first paper discharge roller 30 and the second paper discharge roller 31 are connected by a gear train from the paper feed roller 21, they rotate synchronously. The paper is conveyed without being slacked or pulled.

(1-2c) Recording Unit The recording unit mainly includes a recording head 11 and a carriage 13 that mounts the recording head 11 and scans in a direction intersecting (substantially orthogonal to) the recording sheet conveyance direction. The carriage 13 is supported by a guide shaft 14 and a guide rail 15 that is a part of the chassis 10. The carriage 13 receives a driving force of the carriage motor 17 via a carriage belt 16 stretched by a carriage motor 17 and an idler pulley 20. By transmitting, the carriage 13 is scanned in both directions.

  The recording head 11 has a plurality of ink flow paths connected to the ink tank 12, and the ink flow paths are connected to a discharge nozzle row disposed on a surface facing the platen 29. In the vicinity of the ejection nozzle row, an ink ejection actuator provided for each ejection nozzle is arranged. As the discharge actuator, an actuator that utilizes a liquid film boiling pressure by an electro-thermal conversion element, an electro-pressure conversion element such as a piezo element, or the like is used.

  By transmitting the signal of the head driver 307 to the recording head 11 via the flexible flat cable 73, it is possible to eject ink droplets according to the recording data. Further, by reading the code strip 18 stretched on the chassis 10 by the CR encoder sensor 19 mounted on the carriage 13, ink droplets can be ejected toward the recording paper at an appropriate timing. In this way, when the recording for one line is completed, the recording paper is conveyed by a necessary amount by the above-described paper conveyance unit. By repeating this operation, the recording operation over the entire surface of the recording paper becomes possible.

(1-2d) Recording Head Maintenance Unit The recording head maintenance unit is for sucking ink to prevent clogging of the ink discharge nozzles of the recording head 11 and to eliminate stains caused by paper dust, etc., or when the ink tank 12 is replaced. As a role. For this reason, the maintenance unit 36 installed so as to face the recording head 11 at the standby position of the carriage 13 is in contact with the ink ejection surface of the recording head 11 to protect the ink ejection nozzle, and the ink ejection surface. A wiper (not shown) for wiping and a pump (not shown) connected to the cap and generating negative pressure in the cap.

  When the ink in the discharge nozzles of the recording head 11 is sucked out, the cap is pressed against the discharge surface of the recording head 11 and the pump is driven to make the inside of the cap have a negative pressure to suck the ink. There is also a mechanism to move the wiper in contact with the ejection surface in parallel to remove it when ink is adhered to the ejection surface after ink suction or when foreign matter such as paper dust adheres to the ejection surface. Have.

  The above is the schematic operation of the ink jet printer according to the present invention.

(1-3) Carriage Up-and-Down Mechanism FIG. 4 is a schematic perspective view showing a carriage up-and-down mechanism related to the paper gap adjustment provided in the ink jet printer according to the present invention.

  In the figure, 14a is a guide shaft cam R attached to the guide shaft 14, 14b is a guide shaft cam L attached to the guide shaft 14 and 53 is a gear connecting the lift cam gear 52 and the guide shaft cam R14a. Cam idler gear. The guide shaft 4 is supported on both side plates of the chassis 10 as shown in FIG. 1, and a guide elongated hole (not shown) and a guide shaft 14 are fitted, and in the direction indicated by the arrow Z in FIG. Although it can move freely, movement in the direction of the arrow X and the direction of the arrow Y is restricted.

  With this mechanism, the guide shaft 14 that is normally biased downward (in the direction opposite to the arrow Z) by the guide shaft spring 74 is rotated, and the guide shaft cam 14a and the guide shaft cam 14b are moved when the cam idler gear 53 rotates. The guide shaft 14 abuts against the guide slope 56 and moves up and down while rotating.

  FIG. 5 is a schematic side view showing the operation of the carriage vertical mechanism.

  FIG. 5A is a diagram illustrating a state where the carriage 13 is in the first carriage position. In this state, the guide shaft 14 is abutted against the lower limit of the guide slot 57 of the chassis and the position thereof is determined, and the guide shaft cam R14a and the guide slope 56 are not in contact with each other. Normally, this position is the smallest position between the sheets, and is suitable for recording in the highest quality mode using a special recording medium or the like.

  FIG. 5B is a diagram illustrating a state in which the carriage 13 is moved to the second carriage position that is slightly higher. From the first carriage position, as the lift cam shaft 58 rotates, the lift cam gear 52 fixed to the lift cam shaft 58 rotates, and the guide shaft cam R gear 14c rotates via the cam idler gear 53 engaged with the lift cam gear 52. To do. At this time, if the lift cam gear 52 and the guide shaft cam R gear 14c have the same number of teeth, the lift cam shaft 58 and the guide shaft 14 rotate in substantially the same angle in the same direction. The reason why they do not rotate at exactly the same angle is that the lift cam gear 52 and the cam idler gear 53 have their rotational axes fixed, while the guide shaft cam R gear 14c has its guide shaft 14 itself as a rotational axis accompanied with vertical movement. This is because the distance between gears varies.

  With the above operation, when the lift cam shaft 58 rotates in the direction of arrow a in FIG. 5, the guide shaft 14 also rotates in the direction of arrow b in FIG. As a result of this rotation, the guide shaft cam R14a and the guide shaft cam L14b abut against the fixed guide slope 56, and the moving direction of the guide shaft 14 is restricted only in the vertical direction by the guide slot 57 of the chassis 10 as described above. Therefore, it moves to the second carriage position. This second carriage position is preferably set when recording is performed on plain paper or the like in which the deformation of the recording sheet is large and the recording medium and the recording head 11 come into contact with each other at the first carriage position.

  FIG. 5C is a diagram illustrating a state where the carriage 13 is at the highest third position. When the lift cam shaft 58 rotates further than the second carriage position, the radiuses of the cam surfaces of the guide shaft cam R14a and the guide shaft cam L14b become larger and move to a higher position. This third carriage position is suitable when using a recording medium (envelope, CD-R, etc.) that is thicker than usual.

(1-4) Optical Sensor As the optical sensor used in the present embodiment, a color sensor appropriately selected according to the type (color tone) of ink used in the printer, the head configuration, and the like can be used. In other words, for example, a color having excellent light absorption characteristics with respect to the color of a red LED or infrared LED is used, and a printing unit corresponding to the color ink is set as an object of dot alignment processing. From the viewpoint of absorption characteristics, black (Bk) or cyan (C) is preferable, and magenta (M) and yellow (Y) cannot obtain sufficient density characteristics and S / N ratio. Thus, by determining the color to be used according to the characteristics of the LED to be used, it is possible to correspond to each color. For example, by mounting a blue LED, a green LED, etc. in addition to red, dot alignment processing can be performed for each color (C, M, Y) on Bk.

FIG. 6 is a side view schematically showing the attachment state of the reflective optical sensor used in the printer of FIG. FIG. 8 is a schematic diagram for explaining the detection operation by the reflective optical sensor. As shown in FIG. 6, the reflective optical sensor 400 is attached below the carriage 13 and upstream of the recording head in the direction in which the recording medium 405 is conveyed. As shown in FIG. 8, the optical sensor 400 includes a light emitting unit 401 and a light receiving unit 402. Light I _IN 403 emitted from the light emitting unit 401 is reflected by the recording medium 405, and the reflected light I _{REF is} reflected. 404 can be detected by the light receiving unit 402.

  The detection signal is transmitted to a control circuit formed on the electric board of the printer via a flexible cable (not shown), and converted into a digital signal by the A / D converter. The position at which the optical sensor 400 is attached to the carriage 13 is a position (upstream side of the recording head) that does not pass through a portion through which the ejection opening of the recording head 11 passes during scanning in order to prevent adhesion of droplets of ink or the like. Since this sensor 400 can be used with a relatively low resolution, it can be low-cost.

(1-5a) Print Pattern for Recording Position Adjustment In the following description, the ratio of the area recorded by the printer in a predetermined area on the recording medium is referred to as “area factor”. For example, the area factor is 100% if dots are formed entirely within a predetermined area on the recording medium, 0% if no dots are formed at all, and if the recorded area is half the area of the area, the area factor is 50%.

  FIG. 9 is a schematic diagram showing an example of a print pattern for recording position alignment used in the present embodiment.

  In FIG. 9, white dots 501 indicate dots formed on the recording medium by forward scanning (first print), and hatched dots 502 indicate dots formed by backward scanning (second printing). . For the sake of explanation, the dots are distinguished by the presence or absence of hatching, but in this embodiment, each dot is a dot formed by ink ejected from the same recording head, and does not correspond to the color or darkness of the dot. .

  FIG. 9A shows dots when printing is performed in a state where the recording positions are the same in the forward scanning and the backward scanning, and FIG. 9B is a state where the recording positions are slightly shifted, and FIG. ) Indicates dots when printing is performed with the recording position further shifted. As is clear from FIGS. 9A to 9C, in this embodiment, complementary dot formation is performed in both the reciprocating scans. That is, odd-numbered rows of dots are formed in forward scanning, and even-numbered rows of dots are formed in backward scanning. Therefore, in the case of FIG. 9A in which dots formed by reciprocal scanning have a distance corresponding to the diameter of approximately one dot, the recording positions are in alignment.

  This print pattern is designed so that the density of the entire print portion decreases as the recording position shifts (as the amount of recording position deviation increases). That is, the area factor is approximately 100% within the patch range as the print pattern in FIG. Then, as shown in FIGS. 9B to 9C, as the recording position is shifted, dots formed by forward scanning (outlined dots) and dots formed by backward scanning (hatched dots). ) And the area that is not printed, that is, the area that is not covered by the dots, increases. As a result, the area factor decreases, so that on average, the overall density decreases.

  In the present embodiment, the recording position is shifted by shifting the print timing. This can be done by shifting the print data. Although FIG. 9A to FIG. 9C show one dot unit in the scanning direction, an appropriate unit can be set according to the accuracy of registration adjustment or the accuracy of registration detection.

  FIG. 10 is a schematic diagram showing another example of a print pattern for recording position alignment used in the present embodiment. In this example, a case is shown in which dots are formed by reciprocating each scan in units of four rows of dots.

  In FIG. 10, FIG. 10 (A) shows the dots when the printing positions are aligned, FIG. 10 (B) shows a slightly shifted state, and FIG. 10 (C) shows the dots when printed in a further shifted state. . The intent of these patterns is to reduce the area factor while the reciprocal recording positions deviate from each other. This is because the density of the print portion strongly depends on the change of the area factor. That is, the density increases due to the overlapping of dots, but the increase in the unprinted area has a greater influence on the average density of the entire print section.

  FIG. 11 shows the amount of shift of the recording position and the change in reflection optical density in the print patterns shown in FIGS. 9A to 9C and FIGS. 10A to 10C of this embodiment. It is a graph which shows the outline of these relationships.

In FIG. 11, the vertical axis represents the reflection optical density (OD value), and the horizontal axis represents the recording position shift amount (μm). When the incident light I _IN 403 and the reflected light I _REF 404 shown in FIG. 8 are used, the reflectance R = I _REF / I _IN and the transmittance T = 1−R.

Here, when the reflection optical density is d, there is a relationship of R = 10 ^−d . Since the area factor is 100% when the amount of recording position deviation is 0, the reflectance R is the smallest. That is, the reflection optical density d is maximized. The reflected optical density d decreases even if the recording position is relatively shifted in any direction of + −.

(1-5b) Recording Position Alignment Processing FIG. 13 is a flowchart showing an outline of recording position alignment processing according to the present invention.

  As shown in FIG. 13, first, in step S101, a print pattern is printed. Next, in step S102, the optical sensor 400 measures the optical characteristics of the print pattern. In step S103, an appropriate recording alignment condition is obtained based on the optical characteristics obtained from the measured data. The alignment condition can also be obtained by curve approximation. In step S104, a change in drive timing is set according to the alignment condition.

  FIG. 12 shows a state where the print patterns shown in FIGS. 10A to 10C are printed on the recording medium 405. In the present embodiment, seven patterns A1 to A7 having different relative displacement amounts between forward scanning and backward scanning are printed. Each printed pattern is also called a patch, for example, a patch A1, A2, or the like. In these seven patterns A1 to A7, for example, the forward scanning is fixed at the recording start timing of the forward scanning and the backward scanning. On the other hand, the backward scanning start timing is printed at a total of seven timings: a currently set start timing, three earlier timings, and three later timings. Such setting of the recording start timing and printing of the seven patterns A1 to A7 based thereon can be executed by a program activated by a predetermined instruction input.

  The recording medium 405 and the carriage 13 are moved so that the optical sensor 400 mounted on the carriage 13 is at a position corresponding to the patch A1 or the like as a printed pattern printed in this way, and the carriage 13 is stopped. In the state, the optical characteristics of each patch A1 and the like are measured (see FIG. 6). As described above, the measurement with the carriage 13 stationary can avoid the influence of noise due to the driving of the carriage 13.

  Of course, the optical characteristics of the patterns A1 to A7 in FIG. 12 may be measured while moving the carriage. Further, the size of the measurement spot of the optical sensor 400 may be changed. For example, by increasing the distance between the sensor 400 and the recording medium 405 and by increasing the distance to the dot diameter, it is possible to average variations in local optical characteristics (for example, reflected optical density) on the printed pattern, The reflection optical density of the patch can be measured with higher accuracy.

[First Embodiment]
The first embodiment of the recording alignment process in the ink jet printer according to the present invention described above will be described. In the first embodiment, control is performed so that the recording position alignment processing is automatically performed for each of a plurality of settable paper intervals.

  The recording position alignment process in the first embodiment will be described with reference to the flowchart of FIG.

  First, in step S201, the carriage is set to a reference inter-paper position. Next, in step S202, the recording position alignment process (dot alignment adjustment) described with reference to FIG. 13 is automatically performed for the gap between the sheets, and all adjustment values necessary for the adjustment are obtained. In step S203, the adjustment value obtained in step S202 is stored in a predetermined storage area (a predetermined storage area such as an EEPROM) of the printer main body as a dot position adjustment value between papers subjected to automatic dot alignment adjustment.

  In step S204, it is determined whether or not dot alignment adjustment has been performed for all settable paper gap positions. If there is a paper gap that has not yet been performed, the process advances to step S205 to perform automatic dot alignment adjustment. The position is changed to the next non-paper position, and the process proceeds to step S202. In step S205, if all automatic dot alignment adjustments have been completed for all paper intervals, the process ends.

  Here, a supplementary description will be given of the change of the inter-sheet position in step S205. It is assumed that there are three levels of inter-paper positions, a, b, and c (the height increases in the order of a <b <c). As described with respect to the vertical mechanism of the carriage with reference to FIG. 5, when the paper gap position is changed up and down, the paper gap position can be changed in the order of a → b → c → a, but b → a, c → It cannot be changed in the order of b. That is, in the change of the inter-paper position in step S205, if the standard inter-paper position is b, the next automatic dot alignment adjustment is performed at the inter-paper position c, and finally the automatic dot alignment for the inter-paper position a. It is performed in the order along the carriage up-and-down mechanism so that the alignment adjustment is performed.

  The order of the inter-paper positions for performing this automatic dot alignment adjustment does not need to be specified. However, if the order according to the system of the carriage up-and-down mechanism is used in this way, the time will be reduced and automatic dots will be reduced. Alignment can be adjusted.

  As described above, according to the present embodiment, it is possible to automatically obtain the recording position adjustment value for each sheet spacing while reducing the burden on the user, and to prevent the deterioration of the recording image quality at all the sheet spacing positions. It becomes.

[Second Embodiment]
The second embodiment of the recording position alignment process in the ink jet printer according to the present invention will be described below. In the following description, description of parts similar to those of the first embodiment will be omitted, and description will be made focusing on characteristic parts of the present embodiment.

  In the first embodiment, automatic dot alignment adjustment is performed for each settable paper interval. In the second embodiment, automatic dot alignment adjustment is performed only for a reference paper interval, and correction is performed for other paper intervals. It is controlled to obtain a value.

  The recording alignment process in the second embodiment will be described with reference to the flowchart of FIG.

  First, in step S301, the inter-paper position is set to a standard inter-paper position (inter-paper position where automatic dot alignment adjustment is performed), and automatic dot alignment adjustment is performed. In step S302, the inter-paper correction value calculation patterns (patches) 1 to 7 described with reference to FIG. 12 are recorded on the recording medium. Next, in step S303, the patch recorded in step S302 is scanned by an optical sensor, and the reflected optical density of each patch is measured. Proceeding to step S304, a patch in which the reflection optical density in the state where the recording position is matched is maximized is obtained from the patches.

  In step S305, it is determined whether or not the currently set paper gap position is the reference paper gap position. If it is the reference inter-sheet position, the process proceeds to step S306, and the patch position α at which the optical characteristic shows the maximum value is stored in a predetermined storage area of the printer. For example, when the optical characteristic of the patch 4 is the maximum among the patches 1 to 7, α = 4 is stored. In step S310, it is determined whether correction values have been calculated for all the inter-paper positions. If all the correction values have been calculated, the process ends.

  If the correction value calculation has not been completed for all the sheet intervals in step S310, the process proceeds to step S311 to change to the next sheet interval where correction value calculation has not been performed, and the process returns to step S302 and the subsequent processing is repeated.

If it is determined in step S305 that the position is not the reference inter-sheet position, the process advances to step S307 to store the patch position α _{n at} which the optical characteristic is the maximum value in a predetermined storage area. In step S308, β _n = α _n −α is calculated, and a paper gap correction value β _n is calculated. Next, it progresses to step S309, (beta) _n is memorize | stored in a predetermined storage area, and it progresses to step S310.

  In the present embodiment, the reference inter-paper position is set to the inter-paper position corresponding to a recording medium capable of recording with the highest image quality (high resolution). This is for giving priority to the recording position alignment in the high-quality recording in which the alignment error is most easily visually recognized.

Here, the subscript _n in α _n and β _n indicates the number of steps larger than the reference inter-paper position. For example, the currently set inter-paper position (inter-paper position B) is When the paper interval is one step larger than the reference paper gap position, n = 1, and when the paper interval is two steps larger, n = 2.

As an example, consider the case where the optical characteristics at the position between two sheets are as shown in the graph of FIG. The currently set paper gap position is the paper gap position B, which is one level larger than the paper gap position A which is the reference paper gap position, that is, n = 1, and between adjacent patches. The shift amount (unit) is assumed to be 1/600 inch. As shown in the drawing, the patch position at which the optical characteristic is maximum at the inter-paper position B is α ₁ = 5, and the patch position at which the optical characteristic is maximum at the inter-paper position A is α = 4. Accordingly, the correction value for the inter-paper position (inter-paper position B) that is one step larger than the reference inter-paper position (inter-paper position A) is β ₁ = 5-4 = + 1. Therefore, the dot position adjustment value at this inter-paper position (inter-paper position B) is a value obtained by adding +1 (1/600 inch unit) as a correction value to the dot position adjustment value obtained at the reference inter-paper position. Use it.

  Further, in the processing described with reference to FIG. 16 above, correction at each inter-paper position is performed by recording a patch for calculating the inter-paper correction value at all the inter-paper positions and detecting a patch having the maximum optical characteristic. Although the values are calculated, it is not necessary to record the patches at all the inter-paper positions in consideration of shortening the time required for the dot alignment process and reducing the recording medium and ink to be used. For example, as shown in FIG. 7, when there are three paper spacing positions A, B, and C, patches are recorded and optically recorded at the reference paper spacing position A and other paper spacing positions C. The characteristics are compared, and a correction value for the inter-paper position C is calculated first. Based on the correction value at the inter-paper position C, the correction value for the remaining inter-paper position B where the correction value is not calculated is calculated from a fixed correction value, a ratio between the papers, and the like using a predetermined calculation formula, table, or the like. May be used to derive.

  As described above, according to the present embodiment, the recording position adjustment value or the correction value is automatically obtained for each sheet interval while reducing the burden on the user, and the recording image quality deteriorates at all sheet intervals. Can be prevented.

<Other embodiments>
In the above-described embodiment, the number of patches (patterns) used for dot alignment adjustment is seven (the one that matches the recording position is the middle, and the left and right are shifted by three stages). There is no particular limitation. Therefore, the number of dots may be reduced in consideration of shortening the time required for the dot alignment process and the reduction of the recording medium and ink to be used. May be increased. For example, only one patch may be used, a difference in reflection optical density thereof may be obtained, and alignment at each inter-paper position may be performed based on the difference in reflection optical density.

  In addition, in the above-described embodiment, the case where the recording position is adjusted by scanning in both directions in bidirectional recording at each sheet-to-sheet position has been described as an example. It can also be applied to alignment. For example, in a recording apparatus having a plurality of recording heads corresponding to the type of recording agent (ink) to be used, it is possible to require a position alignment between the plurality of recording heads.

  In this case, in addition to the above-described pattern for recording alignment in scanning in both directions, different types of alignment patterns such as an alignment pattern between recording heads are recorded simultaneously or successively, and a plurality of different types are recorded. The positioning process may be executed.

  In the above embodiment, the patch having the highest reflection optical density is selected as the aligned patch. However, as described in JP-A-11-291553, the patch having the highest reflection optical density is selected. Two linear equations are obtained from the reflection optical density data of the patch and the adjacent patches using the least square method, etc., and the reflection optical density value corresponding to the intersection of the two linear equations is maximized. It is good as a value. Further, in addition to such linear approximation, it can also be obtained by curve approximation. According to these approximation methods, it is possible to realize recording position alignment processing with a finer pitch or higher resolution than recording position alignment conditions such as a pitch used for recording a pattern.

  Further, in the above embodiment, the alignment is performed based on the position (number) of the patch having the highest reflection optical density. However, the alignment is performed based on the maximum value of the reflection optical characteristic value at each inter-paper position. May be performed.

  Further, the present invention is not limited by the operation principle or configuration of the recording head. That is, the recording head is provided with a heating element (electric / thermal energy conversion element such as a heater) in the vicinity of the discharge port, and an electric signal is applied to the heating element to locally heat the ink and cause a pressure change. A thermal system in which ink is ejected from an ejection port may be used, or a piezoelectric system in which mechanical pressure is applied to ink using an electrical / pressure converting means such as a piezo element to eject ink.

  In the above embodiment, the serial type ink jet printer has been described as an example. However, the applicable recording method is not limited to the serial type, and can be recorded at a plurality of inter-paper positions. For example, the present invention can also be applied to recording apparatuses of other recording methods such as a recording apparatus having a full-line type recording head corresponding to the width of the recording medium.

  The form of the recording apparatus according to the present invention is not limited to an image output apparatus of an information processing apparatus such as a computer or a word processor, but is provided integrally or separately, and a copying apparatus combined with a reading apparatus and a communication function are provided. It may be a facsimile machine or the like.

  In the present invention, a software program for realizing the functions of the above-described embodiment (in this embodiment, a program corresponding to the flowcharts shown in FIGS. 13, 15, and 16) is directly or remotely supplied to a system or apparatus. However, this includes a case where the system or apparatus computer also achieves by reading and executing the supplied program code. In that case, as long as it has the function of a program, the form does not need to be a program.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. That is, the claims of the present invention include the computer program itself for realizing the functional processing of the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

It is a typical perspective view showing the whole composition in the state where the cover of the ink-jet printer concerning the present invention was removed. FIG. 2 is a schematic side cross-sectional view showing the overall configuration of the recording apparatus as seen from the direction of arrow A in FIG. 1. It is a block diagram showing the control structure of the whole inkjet printer of FIG. FIG. 2 is a schematic perspective view showing a carriage up-and-down mechanism relating to paper interval adjustment provided in the ink jet printer of FIG. 1. It is a typical side view which shows operation | movement of a carriage raising / lowering mechanism. It is a side view which shows typically the attachment state of the reflection type optical sensor used for the printer of FIG. FIG. 5 is a schematic diagram illustrating a state of ink droplets ejected from a recording head between various papers. It is a schematic diagram for demonstrating the detection operation | movement by a reflection type optical sensor. It is a schematic diagram which shows the example of the print pattern for recording position alignment. It is a schematic diagram which shows another example of the print pattern for recording position alignment. It is a graph which shows the outline of the relationship between the deviation | shift amount of the recording position in a print pattern, and the change of reflection optical density. FIG. 6 is a diagram illustrating a state in which a print pattern is printed on a recording medium 405. 3 is a flowchart showing an outline of a recording position alignment process according to the present invention. It is a graph which shows an example of the optical characteristic in the position between two paper. 5 is a flowchart of a recording position alignment process in the first embodiment. 12 is a flowchart of a recording position alignment process in the second embodiment.

Claims (7)

An inkjet recording apparatus that records on a recording medium by an inkjet recording head that ejects ink,
A paper gap setting means for setting a paper gap, which is a distance between the ejection surface of the print head and the print medium, to one of a plurality of settable distances;
Pattern recording means for recording a pattern for recording alignment on the recording medium in correspondence with the driving condition of the recording head;
Measuring means for measuring the optical characteristics of the pattern;
The drive for each inter-paper distance based on the measurement results of the plurality of patterns recorded corresponding to different inter-paper distances by controlling the inter-paper setting means, the pattern recording means, and the measuring means. An inkjet recording apparatus comprising: an alignment unit that obtains information on conditions.   2. The inkjet recording according to claim 1, wherein the alignment unit obtains the driving condition for each inter-paper distance based on a result of the measurement of the plurality of patterns recorded corresponding to each inter-paper distance. apparatus.   The alignment means obtains the driving condition for the inter-paper distance based on the measurement result of the pattern recorded corresponding to one inter-paper distance, and recorded corresponding to the other inter-paper distance. The inkjet recording apparatus according to claim 1, wherein a correction value of the driving condition for the other inter-paper distance is obtained based on a result of the measurement of the pattern.   4. The ink jet recording apparatus according to claim 3, wherein the one sheet-to-paper distance is a paper-to-paper distance corresponding to a recording medium capable of recording with the highest image quality or high resolution.   Recording is performed by causing the recording head to scan back and forth on a recording medium, and the pattern is a pattern for alignment between recording in forward scanning and recording in backward scanning. The ink jet recording apparatus according to claim 1.   5. The ink jet recording apparatus according to claim 1, wherein a plurality of the recording heads are provided, and the pattern is a pattern for recording position alignment with the plurality of recording heads. A recording position alignment method in an ink jet recording apparatus for recording on a recording medium by an ink jet recording head for discharging ink,
A paper gap setting step of setting a paper gap, which is a distance between the ejection surface of the print head and the print medium, to one of a plurality of settable distances;
A pattern recording step of recording a pattern for recording alignment on the recording medium in accordance with the driving condition of the recording head;
A measuring step for measuring optical characteristics of the pattern;
The driving condition for each inter-paper distance based on the measurement results of the plurality of patterns recorded corresponding to different inter-paper distances by repeating the inter-paper setting step, the pattern recording step, and the measuring unit. An alignment process for obtaining information on the recording position.

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