Recording apparatus and recording method

The present invention relates to a recording device and a recording method, and more particularly to a technique for correcting a transport amount error of a recording medium used in an inkjet recording device.

In an inkjet recording device (recording device), when the recording medium is conveyed, the recording medium may come into contact with the recording head due to the floating or slack of the recording medium, which may cause stains or damage to the recording head. In order to solve such a problem, a technique is known in which the peripheral speed of the transport roller on the upstream side is set higher than that of the paper ejection roller that transports the recording medium on the downstream side in the transport direction (Patent Document 1). ..<patcit num="1"><text>Japanese Patent Application Laid-Open No. 2005-194043</text></patcit>

<p> If the peripheral speed of the transport roller is set higher than that of the paper ejection roller, the recording medium will be transported in excess of the predetermined transport amount when the rear end of the recording medium is separated from the holding portion of the transport roller. Therefore, the image quality may be significantly deteriorated. Therefore, at the timing when the rear end of the recording medium is separated from the holding portion of the transport roller, the peripheral speeds of the transport roller and the paper discharge roller are equal, that is, the peripheral speed ratio of the transport roller and the paper discharge roller is set to "1". , I tried to realize stable transportation.</p><p> Furthermore, as a result of repeated studies by the inventors of the present application, it has been found that the eccentricity of these rollers has a strong influence on the peripheral speed ratio between the transport roller and the paper ejection roller. The eccentricity of the roller means that the cross-sectional shape of the roller is not a perfect circle, the center of rotation of the roller is deviated, and the like. If there is eccentricity of the roller, the length in the circumferential direction (length of the arc) and the peripheral speed will fluctuate depending on the rotation position (rotation phase) of the roller.</p><p> Therefore, the present invention stabilizes the transport amount at the timing when the recording medium is separated from the transport roller by controlling the transport amount of the transport roller and the paper discharge roller based on the degree of eccentricity of the transport roller and the paper discharge roller. The purpose is to reduce the deterioration of record quality.</p>

<p> In order to achieve the above object, the present invention has a recording head for ejecting ink and a first roller arranged on the upstream side of the recording head in the transport direction of the recording medium and for transporting the recording medium. And a second roller arranged on the downstream side in the transport direction for transporting the recording medium, and a first correction value for correcting the transport amount when the recording medium leaves the first roller. And a transfer control means for controlling the transfer of the recording medium based on the second correction value for correcting the phase of the first and second rollers when leaving the first roller. The transport control means is characterized in that the use of the first and second correction values is switched according to the transport path of the recording medium.</p>

<p> According to the present invention, it is possible to stabilize the transport amount at the timing when the recording medium is separated from the transport roller and reduce the deterioration of the recording quality.</p>

1 to 9 are diagrams for explaining the configuration of the inkjet recording apparatus according to the embodiment of the present invention. Hereinafter, the configuration of each part of the recording device will be described in detail with reference to FIGS. 1 to 9.

(A) Paper feed section (Figs. 1 to 4) The paper feed unit includes a pressure plate M2010 for loading recording media, a paper feed roller M2080 for feeding recording media one by one, a separation roller M2041 for separating recording media, and a return lever M2020 for returning the recording media to the loading position. It is configured by being attached to the base M2000.

(B) Paper transport section (Figs. 1 to 4) With reference to FIGS. 1 to 4, the paper transport section mainly carries the transport roller M3060, which is the first roller for transporting the recording medium, and the paper end sensor (PE sensor) to the chassis M1010 made of bent sheet metal. E0007 is rotatably attached and configured. The transport roller M3060 has a structure in which the surface of a metal shaft is coated with fine ceramic particles. In addition, by urging the transfer roller M3060 attached to the chassis M1010 while the metal parts of both shafts are received by bearings (not shown), an appropriate amount of load is applied during rotation to enable stable transfer. ing.

A plurality of driven pinch rollers M3070 are provided in contact with the transport roller M3060. The pinch roller M3070 is held by the pinch roller holder M3000, but is urged by a pinch roller spring (not shown) to press contact with the transfer roller M3060, where the transfer force of the recording medium is generated. At this time, the rotating shaft of the pinch roller holder M3000 is attached to the bearing of the chassis M1010 and rotates around this position.

A paper guide flapper M3030 and a platen M3040 for guiding the recording medium are arranged at the inlet where the recording medium is conveyed. Further, the pinch roller holder M3000 is provided with a PE sensor lever M3021, and the PE sensor lever M3021 plays a role of transmitting the detection of the front end and the rear end of the recording medium to the PE sensor E0007. The platen M3040 is mounted and positioned on the chassis M1010. The paper guide flapper M3030 can rotate around a bearing portion (not shown) and is positioned by abutting on the chassis M1010. A recording head 4 (FIG. 13) is provided on the downstream side of the transfer roller M3060 in the recording medium transfer direction.

The transport process in the above configuration will be described. The recording medium sent to the paper transport unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and is fed to the roller pair of the transport roller M3060 and the pinch roller M3070. At this time, the PE sensor lever-M3021 detects the tip of the recording medium, thereby determining the recording position with respect to the recording medium. The roller pair consisting of the transfer roller M3060 and the pinch roller M3070 is rotated by the drive of the LF motor E0002, and the recording medium is conveyed on the platen M3040 by this rotation. The platen M3040 is formed with ribs that serve as a transport reference surface, and these ribs control the gap between the recording head H1001 and the surface of the recording medium. At the same time, the ribs, together with the paper ejection portion described later, also play a role of suppressing the waviness of the recording medium.

(C) Paper ejection section (Figs. 1 to 4) With reference to FIGS. 1 to 4, the paper ejection section is composed of a first paper ejection roller M3100 and a second paper ejection roller M3110 that function as a second roller, a plurality of spurs M3120, a gear train, and the like. There is. The first paper ejection roller M3100 is configured by providing a plurality of rubber portions on a metal shaft. The drive of the first paper ejection roller M3100 is performed by the drive of the transport roller M3060 being transmitted to the first paper ejection roller M3100 via the idler gear.

The second paper ejection roller M3110 has a configuration in which a plurality of elastomer elastic bodies M3111 are attached to a resin shaft. The drive of the second paper ejection roller M3110 is performed by transmitting the drive of the first paper ejection roller M3100 via the idler gear.

The spur M3120 is formed by integrating a circular thin plate made of, for example, SUS, which is provided with a plurality of convex shapes around it, with a resin portion, and is attached to the spur holder M3130. This attachment is performed by a spur spring having a coil spring provided in a rod shape, and at the same time, the spring force of the spur spring brings the spur M3120 into contact with the paper ejection rollers M3100 and M3110 at a predetermined pressure. With this configuration, the spur M3120 can rotate in accordance with the two paper ejection rollers M3100 and M3110. Some of the spurs M3120 are provided at the position of the rubber part of the first paper ejection roller M3100 or the elastic body M3111 of the second paper ejection roller M3110, and mainly play a role of generating the carrying force of the recording medium. There is. In addition, some of the others are provided at positions where there is no rubber portion or elastic body M3111, and mainly play a role of suppressing the lifting of the recording medium during recording.

Further, the gear train plays a role of transmitting the drive of the transport roller M3060 to the paper ejection rollers M3100 and M3110.

A paper edge support (not shown) is provided between the first paper ejection roller M3100 and the second paper ejection roller M3110. The paper edge support plays a role of protecting the recording made on the recording medium from scratches on the carriage by lifting both ends of the recording medium and holding the recording medium at the tip of the first paper ejection roller M3100. .. Specifically, a resin member provided with a roller (not shown) at the tip is urged by a paper edge support spring (not shown) and pressed against the recording medium at a predetermined pressure to lift both ends of the recording medium. , It is configured to make a strain and hold it in place.

With the above configuration, the image-formed recording medium is sandwiched between the nips of the first paper ejection roller M3110 and the spur M3120, conveyed, and discharged to the paper ejection tray M3160. The output tray M3160 is divided into a plurality of pieces and can be stored in the lower part of the lower case M7080, which will be described later, and is pulled out when used.

In addition, the output tray M3160 is designed so that the height rises toward the tip and both ends are held at high positions, improving the loadability of the discharged recording medium and rubbing the recording surface. Is being prevented. The same roller diameter is used for the first paper ejection roller M3100 and the second paper ejection roller M3110, and the transport error when the first paper ejection roller 3100 and the second paper ejection roller 3110 are transported. Will show the behavior of a stable periodic function with the circumference of both paper ejection rollers as the period. Further, the first paper ejection roller M3100 is equipped with an optical sensor (not shown) for detecting the phase. The origin is the timing at which the flag on the protrusion passes through the sensor.

(D) Recording head (Fig. 8) Ink is ejected from the recording head 4 attached to the carriage 7 to the recording medium conveyed to the recording position by the paper feeding unit and the paper conveying unit, and image recording is performed on the recording medium. As a form of the recording head 4, a method is provided in which a means for generating thermal energy (for example, a heat generation resistance element) is provided as energy used for ejecting ink, and the thermal energy causes a change of state of ink (film boiling). It can be used. Further, it is also possible to use a method in which an element for generating mechanical energy such as a piezo element is provided as an energy generating means and ink is ejected by the mechanical energy.

The recording device of the present embodiment forms an image with 10 colors of pigment ink. The 10 colors are cyan (C), light cyan (Lc), magenta (M), light magenta (Lm), yellow (Y), 1st black (K1), 2nd black (K2), red (R), green. (G) and Gray. The ink of K is the ink of the first black K1 or the second black K2 described above. Here, the inks of the first black K1 and the second black K2 are a photo black ink that realizes a high glossy recording with respect to glossy paper and a matte black ink suitable for matte paper without glossiness, respectively. be able to.

FIG. 8 schematically shows a state in which the recording head 4 adopted in the present embodiment is viewed from the nozzle forming surface side. The recording head 4 of this example has two recording element substrates H3700 and a recording element substrate H3701 in which nozzle rows of 5 colors out of the above 10 colors are formed. H2700 to H3600 are nozzle rows corresponding to 10 different colors of ink.

On one of the recording element substrates H3700, each nozzle row H3200, H3300, H3400, H3500 and H3600 is formed by supplying inks of gray, light cyan, first black, second black and light magenta to perform ejection operation. .. On the other recording element substrate H3701, nozzle rows H2700, H2800, H2900, H3000 and H3100 are formed in which cyan, red, green, magenta and yellow inks are supplied to perform ejection operations. Each nozzle row is composed of 768 nozzles arranged at intervals of 1200 dpi (dot / inch; reference value) in the transport direction of the recording medium, and ejects about 3 picolitres of ink droplets. The opening area at each nozzle discharge port is set to approximately 100 square μm.

With such a head configuration, it is possible to execute so-called one-pass recording in which recording for the same area on the recording medium is completed by one main scan. However, in order to reduce variations in nozzles and improve recording quality, it is also possible to perform so-called multipath recording in which recording for the same scanning area on a recording medium is completed by a plurality of main scans. The number of passes during multipath recording is appropriately determined according to the recording mode and other conditions.

A plurality of independent ink tanks are detachably attached to the recording head 4 according to the color of the ink used. Alternatively, ink may be supplied from an ink tank provided at a fixed portion of the device via a liquid supply tube.

In the non-recording area, which is within the movable range of the recording head 4 in the main scanning direction and outside the side end of the recording medium P or the platen 3, the recovery unit 11 can face the discharge surface of the recording head 4. Is placed. The recovery unit 11 has a known configuration as shown below. That is, a cap portion that caps the ejection surface of the recording head 4, a suction mechanism that forcibly sucks ink from the recording head 4 with the ejection surface capped, a cleaning blade that wipes off dirt on the ink ejection surface, and the like.

The carriage 7 is equipped with a reading sensor (scanner) (not shown), and can read the density of a test pattern for correcting the amount of transport, which will be described later.

(E) Flat path section (Figs. 5-7) As shown in FIG. 4, the paper feed from the paper feed unit is bent until the path through which the recording medium passes reaches the pinch roller, so that the paper feed is performed in a bent state. Therefore, for example, when an attempt is made to feed a thick recording medium having a thickness of about 0.5 mm or more from the paper feeding unit, a reaction force of the bent recording medium is generated, and the paper feeding resistance increases, so that the paper feeding may not be performed. Further, even if the paper can be fed, the recording medium after the paper is ejected may remain bent or may be broken.

Flat path recording is used for recording on a recording medium that is not bent, such as a thick recording medium, or a recording medium that cannot be bent, such as a CD-R.

Here, there is a type of flat path recording in which a recording medium is nipped into a pinch roller of the main body from an opening on a slit on the back of the main body (under the paper feeding device) in a manual feeding manner to perform recording. However, the flat path recording of the present embodiment is a form in which the recording medium is fed from the paper ejection port in front of the main body to the recording position, switched back, and then recorded.

The front cover M7010 is located below the paper ejection section to double as a tray for loading dozens of recording media that are normally recorded (Fig. 1). During flat-pass recording, raise the front tray M7010 to the position of the output port in order to feed the recording medium horizontally from the output port and in the direction opposite to the normal transport direction (Fig. 5). The front tray M7010 is provided with hooks (not shown), and the front tray can be fixed at the flat path paper feed position. The fact that the front tray M7010 is in the flat path recording position can be detected by the sensor, and the flat path recording mode can be determined according to the detection.

In the flat pass recording mode, the flat pass key E3004 is first operated in order to place the recording medium on the front tray M7010 and insert the recording medium through the output port. Then, the spur holder M3130 and the pinch roller holder M3000 are lifted to a position higher than the assumed thickness of the recording medium by a mechanism (not shown). It is also possible to open the rear tray M7090 by pressing the rear tray button M7110 and then open the rear sub tray M7091 in a V shape (Fig. 6). The rear tray M7090 and the rear sub tray M7091 are trays for supporting the long recording medium on the back of the main body because they protrude from the back of the main body when the long recording medium is inserted from the front of the main body. If a thick recording medium is not kept in a flat posture during recording, it may rub against the head face surface and the transport load may change, which may affect the recording quality. Therefore, the arrangement of these trays is effective. Is. However, it is not necessary to open the rear tray M7090 or the like as long as the recording medium has a length that does not protrude from the back of the main body.

As described above, the recording medium can be inserted into the main body from the paper ejection port. The procedure for transporting the recording medium in the platform mode will be described with reference to FIG. 7. First, the rear end portion (the front end portion located closest to the user) and the right end portion of the recording medium are aligned with the marker positions of the front tray M7010 and placed on the front tray M7010.

When the flat passkey E3004 is operated again here, the spur holder 3130 descends and the paper ejection rollers M3100 and M3110 and the spur 3120 nip the recording medium. After that, the paper ejection rollers M3100 and M3110 pull the recording medium into the main body by a predetermined amount (in the direction opposite to the transport direction during normal recording). When the recording medium is first set, the front end (rear end) of the recording medium is aligned, so the front end (the innermost end when viewed from the user) of the short recording medium is the transport roller M3060. May not reach. Therefore, the predetermined amount is the distance until the rear end of the assumed shortest recording medium reaches the transport roller M3060. Since the recording medium sent in a predetermined amount reaches the transfer roller M3060, the pinch roller holder M3000 is lowered at that position, and the transfer roller M3060 and the pinch roller M3070 nip the recording medium. This completes the paper feeding for flat path recording of the recording medium (recording standby position).

The nip force between the paper ejection rollers M3100 and M3110 and the spur M3120 is set relatively low so as not to affect the formed image during paper ejection during normal recording. Therefore, during flat path recording, the position of the recording medium may shift before recording. However, in the present embodiment, since the recording medium is nipated by the transport roller M3060 and the pinch roller M3070 having a relatively high nip force, the setting position of the recording medium is secured. Further, when the above-mentioned predetermined amount of the recording medium is sent into the main body, the flat pass paper detection sensor M3170 between the platen M3040 and the spur holder M3130 detects the rear end position (the front end position during recording) of the recording medium. be able to.

When the recording medium is set to the recording standby position, the recording command is executed. That is, the recording medium is conveyed by the transfer roller M3060 to the recording position by the recording head H1001, the recording is performed in the same manner as the normal recording operation, and the paper is discharged to the front tray M7010 after recording.

If further flat path recording is desired, the recorded recording medium may be taken out from the front tray M7010, the next recording medium may be set, and the above-described processing may be repeated. Specifically, by pressing the flat passkey E3004, the spur holder M3130 and the pinch roller holder M3000 are lifted and the recording medium is set.

On the other hand, when the flat path recording is finished, the normal recording mode can be returned by returning the front tray M7010 to the normal recording position.

(F) Electric circuit configuration FIG. 9 shows a configuration example of the main part of the control system of the recording device. Here, 100 is a control unit that controls each drive unit of the recording device. The control unit 100 includes a CPU 101, a ROM 102, an EEPROM 103, and a RAM 104. The CPU 101 performs various calculations and determinations for processing related to recording operations and the like, including a processing procedure described later, and also performs processing on recorded data and the like. The ROM 102 stores programs corresponding to the processing procedures executed by the CPU 101 and other fixed data. The EEPROM 103 is a non-volatile memory, and is used to retain predetermined information even when the power of the recording device is turned off. The RAM 104 temporarily stores the recorded data supplied from the outside and the recorded data expanded according to the device configuration, and also functions as a work area for arithmetic processing by the CPU 101.

The interface (I / F) 105 has a function of connecting to an external host device 1000, and performs two-way communication with the host device 1000 based on a predetermined protocol. The host device 1000 has a computer or other known form, and a printer driver, which is a program for causing the recording device of the present embodiment to perform recording as a supply source of recorded data and performing the recording operation, is used. It is installed. That is, the printer driver sends recording setting information such as recording data and information on the type of recording medium on which the recording data is recorded, and control commands for controlling the operation of the recording device.

The linear encoder 106 detects the position of the recording head 4 in the main scanning direction. The sheet sensor 107 is provided at an appropriate position on the recording medium transport path. By detecting the front and rear ends of the recording medium using the sheet sensor 107, the transport (secondary scanning) position of the recording medium can be known. The motor drivers 108 and 112 and the head drive circuit 109 are connected to the control unit 100. The motor driver 108 drives the transport motor 110, which is the transport drive source for the recording medium, under the control of the control unit 100. The driving force of the transfer motor 110 is transmitted to the transfer roller M3060, the paper ejection roller 3100, and the paper ejection roller 3110 via a transmission mechanism such as a gear. The motor driver 112 drives the carriage motor 114, which is a driving source for the movement of the carriage 7. The driving force of the carriage motor 114 is transmitted to the carriage 7 via a transmission mechanism such as a timing belt. The head drive circuit 109 drives the recording head 4 under the control of the control unit 100 to perform a discharge operation. The rotary encoder 116 is attached to the shaft of the transfer roller M3060, and is used to control the transfer motor by detecting the respective rotation positions and speeds.

(Characteristic configuration of this embodiment) The outline of the transport control characteristic of the recording device of the present embodiment will be described below. First, in the present embodiment, when the recording medium is released from the holding portion of the transport roller M3060, the first correction value for setting the roller peripheral speed ratio between the transport roller and the paper ejection roller to "1" is used. The rotation of the transport roller and the paper output roller, that is, the drive control of the motor is performed. Further, in the rotation phase of the transport roller and the paper discharge roller when the roller peripheral speed ratio becomes the maximum or the minimum, the initial phases of the transport roller and the paper discharge roller are adjusted so that the recording medium separates from the holding portion of the transport roller. The second correction value to be used is used.

In the present embodiment, by controlling the transfer amount using the first and second correction values, the transfer amount at the timing when the recording medium is separated from the transfer roller is stabilized, and the deterioration of the recording quality is reduced. be able to.

Further, in the present embodiment, a first transport control that controls the transport amount using both the first and second correction values, and a second transport that controls the transport amount using only the first correction value. The control is switched according to the transport path of the recording medium. As a result, in a recording device having a plurality of transport paths, it is possible to stabilize the transport amount at the timing when the recording medium is separated from the transport roller.

The details of the transport amount control, which is a feature of the present embodiment, will be described below.

1. Procedure for acquiring the transfer amount correction value In the present embodiment, in order to correct the transport amount for each rotation phase of the roller due to the eccentricity of the roller, the transport amount correction is performed by acquiring the transport correction value for each block in which the roller circumference is divided into 110. Is going.

FIG. 10 is a flowchart showing an outline of a processing procedure for acquiring a positive value of the conveyed amount. In this procedure, first, preparations for starting a recording operation including setting and feeding of a recording medium are made, and when the recording medium is conveyed to a predetermined recording position, a test pattern is recorded in the transfer area I ( step S1001). Next, the recording medium is further conveyed, and the test pattern is recorded in the transfer area II (step S1002).

Next, the test pattern is read using the reading sensor 120, and the concentration information is acquired (step S1003). Then, based on this concentration information, the cumulative transport amount error is detected, and the transport correction value is acquired (step S1004).

The details of the test pattern, the transport area, etc. will be described later.

2. Test pattern details First, with reference to FIG. 11, in the present embodiment, the transport areas classified into two along the transport direction Y will be described. In the present embodiment, the area where recording is performed when the paper is transported only by the transport roller and the region where recording is performed when the paper is transported by both the transport roller and the paper ejection roller are referred to as "convey area I". On the other hand, the transport area transported only by the paper ejection roller is defined as "convey area II". Since the transfer roller is the dominant roller in the transfer of the recording medium as compared with the paper output roller, in the present embodiment, the transfer area of only the transfer roller and the transfer area of both the transfer roller and the paper output roller are defined. Both are set as the transport area I.

Next, FIG. 12 shows a test pattern used in this embodiment. The test pattern of this embodiment is recorded for each of the transport areas I and II. Further, in the rotation axis direction X (main scanning direction of the recording head) of each roller, test patterns for detecting the transfer error of each roller are arranged at a position close to the transfer reference and a position away from the transfer reference. Is formed by.

That is, in FIG. 11, FR is a test pattern recorded in the transport area I, FR1 is a test pattern at a position close to the transport reference, and FR2 is a test pattern at a position far from the transport reference. Further, ER is a test pattern recorded in the transport area II, ER1 is a test pattern at a position close to the transport reference, and ER2 is a test pattern at a position far from the transport reference.

When recording the test patterns ER1 and ER2, the pinch roller M3070 can be released after the test patterns FR1 and FR2 are recorded so that the recording medium can be conveyed only by the paper ejection roller. As a result, a sufficient area for recording the test patterns ER1 and ER2 can be secured.

Next, each of the four test patterns recorded on the recording medium will be described.

In one test pattern, a total of 240 patches are recorded using the second black nozzle row H3500, 30 patches along the transport direction Y and 8 patches along the scanning direction X. In the recording of each patch, the first recording scan is performed using 128 nozzles at the upstream end of the central 640 nozzles of the nozzle row equipped with 768 nozzles, and a predetermined image is recorded. After that, the transfer equivalent to 128 nozzles is performed four times each time, and the second recording scan is performed on the predetermined image using the 128 nozzles at the downstream end of the 640 nozzles to complete the patch. The eight patches lined up in the scanning direction X are recorded by shifting the nozzle usage range in the second scan one nozzle at a time to the downstream side in the transport direction from left to right in the figure. .. The shift range is -3 to +4, assuming that the shift to the upstream side is positive.

In the present embodiment, the nozzle row H3500 has nozzles arranged at a pitch of 1200 dpi, and a distance (128/1200 × 25.4 = 2.709 [mm]) corresponding to the range of 128 nozzles is an ideal one-time transport amount. (Transport amount between scans of the recording head). Here, if the transfer is performed with the ideal transfer amount (as designed), with the deviation amount 0, the medium is transferred four times with respect to the predetermined image recorded in the first scan. The images recorded in the fifth main scan just overlap. Further, the positive shift amount corresponds to the transport amount larger than the distance, and the negative shift amount corresponds to the transport amount being smaller. Further, in the present embodiment, the medium transport amount (ideal value) between each main scan is set to 2.709 mm, and by repeating the main scan 30 times, 30 patches are formed over the range of the sub scan direction (convey direction). To be done. Therefore, the length of one test pattern in the sub-scanning direction is 2.709 × 30 = 81.27 mm (ideal amount), which corresponds to more than two rounds when a roller with a nominal outer circumference of 37.19 mm is used. ..

Further, assuming that eight patches arranged in the scanning direction are one patch group, the 30 patch groups arranged in the conveying direction Y are the roller areas used for media transfer between the first recording scan and the second recording scan. Are formed differently from each other. Assuming that the medium transfer after the first recording scan of the most upstream patch group in the transfer direction is performed from the reference position of the roller, when recording the most upstream patch group, the medium transfer is performed four times from the reference position of the roller. It means that the area corresponding to (0 to 10.836 mm) was used. In addition, in the second patch group from the upstream side, an area (2.709 to 13.545 mm) corresponding to four times of medium transfer was used from a position 2.709 mm away from the reference position of the roller. Similarly, the roller region (5.418-18.963 mm) was used in the third patch group, and the roller region (8.127-21.672 mm) was used in the fourth patch group. Thus, in each patch group, different roller regions are used from the first scan to the second scan.

If the image recorded by the upstream nozzle group used for the first scan and the image of the downstream nozzle group used for the second scan overlap, a portion where dots are not recorded occurs in the image. The concentration (OD value) becomes low. On the other hand, if there is an error in the amount of transport and the images recorded in the first scan and the second scan are misaligned, the blank portion is filled and the density becomes high.

3. Acquisition of transport error The test pattern recorded as described above is read by a scanner, the densities of all patches are detected, and then the densities are compared for each of a plurality of patches recorded in the main scanning direction. Then, the shift amount of the patch having the lowest concentration in the patch group can be obtained as a transport error. However, the above-mentioned transport error is calculated as a cumulative transport error (cumulative of four transport operations) between the first scan and the second scan of the pattern recording. It is preferable that such cumulative transport error is standardized according to a certain reference length. In the present embodiment, the transfer error (cumulative for 640 nozzles) in the four transfer operations is multiplied by 768/640 to convert to the cumulative transfer error in the nozzle row length (equivalent to 640 nozzles).

4. Acquisition of correction value First, a series of procedures for acquiring a correction value will be described with reference to FIG.

In step S2001, it is determined whether the transfer amount should be corrected between the transfer areas I and II (the timing when the rear end of the medium leaves the transfer roller), and if necessary, in step S2002, the cumulative transfer of the transfer areas I and II is performed. Get the error Xn. Further, this cumulative transport error Xn is classified for each block allocated to the rollers (S2003), and if it is determined in step S2004 that it is necessary to acquire the first correction value, the process proceeds to steps S2005 and S2006. The first correction value is acquired for each block in step S2005, and this is written to EEPROM in step S2006. Next, in step S2007, the second correction value is acquired based on the distribution of the first correction value, and this is written to EEPROM (S2007). In step S2008, it is determined whether there is an area for which the correction value needs to be acquired, and the flow is terminated.

The details of this correction value acquisition will be described below.

By the process described in the paragraph of acquiring the transfer error, the cumulative transfer error corresponding to the nozzle length is acquired corresponding to each patch group of the test pattern. As described above, in the present embodiment, since the ideal one-time transport amount is 2.709 mm, 30 cumulative transport error amounts are acquired at 2.709 mm intervals. Further, at the start of test pattern recording, the initial phase of the rollers involved in the medium transfer is acquired. In the present embodiment, the sensor for detecting the phase of the rollers is attached only to the transfer roller M3060, but the transfer roller and the first paper ejection roller have slightly different roller diameters, but the gears that drive both rollers have the same teeth. Due to the number, both rollers are driven in synchronization. Further, since the first paper ejection roller and the second paper ejection roller use rollers having the same diameter, both paper ejection rollers are also driven in a synchronized state. From this, the phase of the first and second paper ejection rollers can be estimated from the phase of the transport roller M3060. Even if the transport roller and both paper ejection rollers have the same roller diameter, all the rollers are driven in synchronization with each other. Therefore, only one of the rollers needs to have a phase detection means. In a system in which none of the rollers are synchronized, it is necessary to provide each roller with a phase detection means.

In the transport amount correction of the present embodiment, a mode is adopted in which each roller is divided into 110 regions and the transport amount is corrected for each region. In addition, the rotary encoder 116 attached to the transfer roller M3060 uses one that outputs 14080 pulses per rotation. Therefore, the 14080 pulse is divided into 128 pulses according to the 110 region, and the current roller position can be detected according to the output pulse of the rotary encoder 116.

FIG. 14 is a plot of the cumulative transport error Xn for each patch group detected from the two test patterns in the transport region I, and n = 1,2, ... From the patch group on the upstream side in the transport direction. Numbered and plotted. In calculating the cumulative transport error, the cumulative transport error X on the transport reference side and the non-reference side, respectively._nH, X_nAIt is calculated as the average value of. However, a numerical value calculated by weighting in consideration of the influence of the laterality of the roller (influence in the direction of the rotation axis) and the deflection may be used.

In the figure, the horizontal axis indicates the patch group number n, which corresponds to the cumulative amount of transport from the initial phase. That is, n corresponds to the amount of transportation from the reference position of the roller, which corresponds to 2.709 mm when n = 1 and 5.419 mm when n = 2.

FIG. 15 is a table showing the cumulative transport amount and the distribution of the phase blocks corresponding to each patch group. The cumulative transfer amount is the transfer amount from the reference position of the roller. If n = 1, it is 2.709 mm, and if n = 14, it is the transfer amount for one round of the roller. Therefore, it is assumed that the initial phase at the time of recording the test pattern of the transport area I is "17 blocks" counting from the reference position among 110, and the initial phase at the time of recording the test pattern of the transport area II is "73 blocks". Furthermore, if the cumulative transport amount of each patch group is 8 blocks and the last patch group of one cycle is divided into 6 blocks, it can be distributed as shown in FIG. Specifically, the patch group with n = 1 has 17 to 24 blocks, the patch group with n = 2 has 25 to 32 blocks, and the patch group with n = 14 has 11 to 16 blocks.

As mentioned above, since this test pattern has a roller circumference of more than 2 laps, it is repeated after n = 15. For the patch group n in which the blocks are distributed in an overlapping manner, the average value of the respective transfer errors is calculated, and the transfer error is uniquely set. In the transport region II, the sorting operation is the same except that the initial phase is different from that in the transport region I.

In the present embodiment, as shown in FIG. 16, 17 to 24 blocks will be described as block group A, 25 to 32 blocks will be described as block group B, and ... 11 to 16 will be described as block group N. If the transport error of one roller or more cannot be obtained at one time due to the configuration of the test pattern, the test pattern is divided into multiple recording media and the test patterns are recorded in different initial phases to record the test pattern for one roller. A transport error can be obtained. Further, a means for predicting the distribution of the transport error for one round may be used.

Next, a method of calculating the first and second correction values for stabilizing the transfer when the recording medium leaves the transfer roller will be described.

In the present embodiment, the first correction value is calculated for each combination of the block groups (roller rotation phase) of the transport areas I and II. That is, the first correction value is calculated so that the peripheral speed ratio of the transport amounts of the transport areas I and II is "1" for all combinations of the block groups. As a result, stable transfer can be obtained regardless of the rotation phase of the transfer roller and the paper ejection roller when the recording medium is released from the holding portion of the transfer roller.

Specifically, the roller peripheral speed V_rIs the transfer amount including the transfer error per transfer of 16 nozzle widths, so as shown in Equation 1, the ideal transfer amount is the value obtained by dividing the transfer error Xn converted by 768 nozzle lengths by 48. Obtained by subtracting from. (Equation 1) V_r= (16/1200 × 25.4)-(-Xn / 48) Further, the calculation of the first correction value (Zn) is obtained by the following equation 2. (Equation 2) First correction value (Zn) = {(peripheral speed V of transport area II)_r(II)) / (Peripheral speed of transport area I (I))-1} * 100 FIG. 18 shows the distribution of the first correction value (Zn), which is a periodic function and has a maximum value and a minimum value.

Therefore, in the rotation phase of the transport roller and the paper discharge roller when the roller peripheral speed ratio becomes the maximum or the minimum, the initial phases of the transport roller and the paper discharge roller are adjusted so that the recording medium separates from the holding portion of the transport roller. Calculate the second correction value. By controlling the transport using such a second correction value, the fluctuation range of the transport amount can be minimized even if the transport amount varies. In the present embodiment, the second correction value depends on the size of the recording medium in the sub-scanning direction so that the recording medium separates from the holding portion of the conveying roller when the block group has the minimum roller peripheral speed ratio. Adjust the roller initial phase.

5. First transport control In the present embodiment, when the paper feed from the ASF paper feed unit is specified as the paper feed transfer path in the recording command received from the host device 1000, the size and recording mode of the recording medium for recording are further read. In this embodiment, since the roller peripheral speed ratio is distributed between the transport areas I and II as shown in FIG. 18, the initial phase of the rollers is adjusted so that the recording medium separates from the sandwiched portion of the transport rollers in the block group G. To do. Each recording medium and each recording mode have a pulse number offset value in the EEPROM 103, which takes into account the size of the recording medium and the carrier correction value depending on the recording mode. The offset value is added in the roller reversal direction from the position of 68 × 128 = 8704 pulses with respect to the origin of the central block 68 of the block group G, and the pulse value of the initial phase is determined. When the phase detection optical sensor confirms that the roller transfer start position (initial phase) has been adjusted to this pulse value, the paper feed operation is started and the recording operation is performed until the rear end of the recording medium passes through the PE sensor E0007. Is carried out.

Further, when the rear end of the recording medium passes through the PE sensor E0007, the roller phase at the time of passing is calculated. In the present embodiment, the timing at which the rear end of the recording medium is detached is predicted at the timing of passing through the PE sensor E0007, but it may be predicted at the time of initial phase adjustment before feeding. However, considering the adverse effect of the predicted phase shift due to slippage of the recording medium with respect to the roller, it is desirable to make a prediction at the timing when the rear end of the medium is separated.

Since the distance from the PE sensor E0007 to the holding portion (nip) between the transport roller M3060 and the pinch roller M3070 is 14.16 mm, the number of pulses of the rotary encoder 116 is 5361 pulses. When the phase of the transport roller M3060 when passing through the PE sensor E0007 is 10, it is 1280 pulses when converted to the number of pulses, so it is 6641 pulses in the forward rotation accompanying the transfer until the rear end of the medium is detached. When this is converted into a phase block, it becomes 52, and the first correction value corresponding to the block group E in the figure is applied. In this way, stable transfer can be realized by correcting the transfer amount error when the rear end of the medium separates from the holding portion of the transfer roller, that is, when the transition from the transfer area I to II occurs.

In the transport amount control when rushing into the paper ejection roller at the tip of the recording medium and the spur nip, the phase at the time of rushing is predicted from the phase at the time of feeding, and the roller peripheral speed between the transport areas before and after the rushing. A correction value that corrects the ratio to "1" may be applied.

6. Second transport control At the time of recording by the flat path of the present embodiment, as described above, the recording medium is recorded from the host device in a state of being nipated in the drive roller system of the transport roller M3060 and the pinch roller M3070, the paper ejection rollers M3100 and M3110 and the spur M3120. Receive a command. Therefore, since it is difficult to adjust the initial phase of the transport roller M3060 using the second correction value, the transport control is performed using only the first correction value.

Specifically, first, the roller initial phase is not adjusted during the flat pass, and the rear end (the tip position during recording) of the recording medium passes through the flat pass paper detection sensor M3170 when the recording medium is fed to the main body. Detect the phase to be used. The size of the recording medium and the number of pulses from the recording mode to the rear end detachment are calculated from the recording command information, and the roller rotation phase at the time of detachment of the rear end of the medium is predicted.

In the recording device of this embodiment, the distance from the nip of the transport roller M3060 and the pinch roller M3070 to the flat pass paper detection sensor M3170 is 52.15 mm. Therefore, when recording an A4 size (297 mm) recording medium with a flat path, the phase is 297-52.15 = 244.85 mm forward-rotated from the phase at which the rear end (tip at the time of recording) of the recording medium is detected, and after the medium. The end will come off. Assuming that the phase of the transport roller M3060 at the time of detecting the rear end by the flat pass paper detection sensor M3170 is "10", the number of pulses is 1280, and when the rear end is separated, it is 9499 pulses. When this is converted into a phase block, it becomes 74, and the first correction value corresponding to the block group H in FIG. 18 is applied.

This embodiment is also applicable to back-feeding after front-side recording by double-sided recording and inverting the recording medium in the paper feed path in the recording device to record the back surface. That is, when the recording on the front surface is completed and the recording on the back surface is started, the drive roller is in the nip state, so that the first correction suitable for the roller peripheral speed ratio corresponding to the phase at the time of the predicted rear end detachment is achieved. The value is applied.

7. Other As described above, in the present embodiment, the first transport control that controls the transport amount using both the first and second correction values, and the second transport amount that controls the transport amount using only the first correction value. The transfer control is switched according to the transfer path of the recording medium. That is, in the normal recording operation by the transport path from the ASF paper feed unit, the recording medium is not niped into the drive roller system while waiting for the recording command, so the second correction value is used. As a result, even if a sudden fluctuation occurs in the conveyed amount when the rear end of the recording medium is detached, the fluctuation range of the conveyed amount can be minimized. Since the transport path is determined from the information of the paper feed means such as the ASF paper feed unit, the first and second transport controls can be switched based on this information.

In addition, when there are multiple unstable transports such as the tip of the medium plunging into the paper ejection roller holding portion and the rear end of the medium detaching, the part where the image is most likely to be affected or the average value of the roller peripheral speed ratio is calculated. It is preferable to adjust the initial phase with reference to the highest point.

Further, in a recording device that is not sandwiched between the drive roller system before feeding, has no detection means for detecting the front and rear ends of the recording medium such as a PE sensor, and has no area for storing the first correction value in EEPROM. Transport control can also be performed as follows. That is, from the distribution of the first correction value shown in FIG. 18, only the phase in which | Zn | is minimized is stored in EPEEOM, and based on this information, it is recorded at the rotation phase position of the roller where the fluctuation of the transport amount error is small. Adjust the initial phase of the rollers before feeding so that the rear end of the medium is detached.

<figref num="1">It is a perspective view of the inkjet recording apparatus in this embodiment, and shows the state seen from the front in use.</figref><figref num="2">It is a figure for demonstrating the internal mechanism of the inkjet recording apparatus main body in this embodiment, and is the perspective view from the upper left part.</figref><figref num="3">It is a figure for demonstrating the internal mechanism of the inkjet recording apparatus main body in this embodiment, and is the perspective view from the upper right part.</figref><figref num="4">It is a side sectional view for demonstrating the internal mechanism of the inkjet recording apparatus main body in this embodiment.</figref><figref num="5">It is a perspective view of the inkjet recording apparatus in this embodiment, and shows the state seen from the front at the time of flat pass recording.</figref><figref num="6">It is a perspective view of the inkjet recording apparatus in this embodiment, and shows the state seen from the back surface at the time of flat pass recording.</figref><figref num="7">It is a schematic side sectional view for demonstrating the flat path recording performed in this embodiment.</figref><figref num="8">It is a schematic explanatory view of the state which the recording head adopted in this embodiment was seen from the nozzle formation surface side.</figref><figref num="9">It is a block diagram which shows the structural example of the main part of the control system of the inkjet recording apparatus in this embodiment.</figref><figref num="10">It is a flowchart which shows an example of the processing procedure of the test pattern recording and the transfer error acquisition of this embodiment.</figref><figref num="11">It is a figure explaining the transport area in this embodiment.</figref><figref num="12">It is explanatory drawing which shows an example of the test pattern used in this embodiment.</figref><figref num="13">It is a flowchart which shows an example of the processing procedure of the correction value acquisition of this embodiment.</figref><figref num="14">It is explanatory drawing which shows by graphing the transport error quantified based on the density information obtained from one test pattern.</figref><figref num="15">It is a table which shows an example of the allocation of the phase block corresponding to the patch row and the cumulative transport error of one test pattern.</figref><figref num="16">It is a table which shows the block group corresponding to the phase block in one test pattern.</figref><figref num="17">It is a table which shows an example of the roller peripheral speed corresponding to each block group in the test pattern of adjacent regions I and II.</figref><figref num="18">It is explanatory drawing which shows the distribution of the roller peripheral speed ratio for each block group in a graph between a certain adjacent regions I and II.</figref>

Code description

M3060 Conveying roller M3100 1st paper ejection roller M3110 2nd paper ejection roller M4000 carriage 101 CPU 110 Conveyor motor P Recording medium