JP2010274483A - Recorder and method of controlling conveyance of recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve highly accurate conveyance and stop at a target position in a recorder which carries out recording by conveying a recording medium to the target position. <P>SOLUTION: The recorder includes: a first conveyance amount detecting means which detects a conveyance amount of the recording medium by detecting a driving amount of a conveying means; and a second conveyance amount detecting means which obtains a plurality of image information of the recording medium surface by different timings using an optical sensor. On the basis of a difference between a detected value of the conveyance amount by the first conveyance amount detecting means obtained along with the conveyance operation to the target position, and a detected value of the conveyance amount by the second conveyance amount detecting means, it is determined whether the recording medium reaches the target position in a permissible error range by the conveyance operation. If the reach is not determined, the conveyance operation to the target position and the determination are repeatedly carried out. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a recording apparatus and a conveyance control method for a recording medium used in the apparatus.

  In a recording apparatus that involves conveying and stopping a recording medium when recording an image, a technique for conveying the recording medium with a desired amount with high accuracy is required in order to achieve high image quality. In order to transport the recording medium with high accuracy, it is important to detect the transport amount, and various proposals have been made.

  A typical example thereof is one that uses a rotary encoder having a rotation angle sensor and a code wheel having slits engraved at a predetermined equal interval or equal angle with respect to a rotation system that conveys a recording medium. It is done. Here, the code wheel is fixed on the same rotation shaft as that of the conveyance roller for conveying the recording medium, for example. Slits are cut at equal intervals or at equal angles along the circumference of the code wheel, and a rotation angle sensor fixedly installed in the recording apparatus confirms the position of this slit. For example, an optical transmission sensor is used as the rotation angle sensor, and a slit that moves as the code wheel rotates is detected based on the presence or absence of light transmission, and a pulse signal is output at the detected timing. The rotation angle of the code wheel is detected by counting the pulse signals, and the position, velocity, and acceleration of the recording medium are calculated from the time interval at which the pulse signals are transmitted. Furthermore, the rotation speed of the conveyance roller and the conveyance amount of the recording medium can be detected by using the obtained values, and can be used for conveyance control.

  However, the conveyance rollers to which the code wheel is attached may have variations in outer diameter due to manufacturing errors. Then, even when the same rotation angle is detected, it is difficult to accurately detect the conveyance amount due to the variation in the conveyance amount due to the variation in the outer diameter of the conveyance roller. This is because, for the same rotation angle, a conveyance roller having a large outer diameter increases the conveyance amount, whereas a conveyance roller having a small outer diameter decreases the conveyance amount. Even if the outer diameter dimension is formed with high accuracy, the transport roller may be eccentric due to an attachment error to the recording apparatus. Then, even when the same rotation angle is detected, the detection amount varies depending on the phase of the transport roller.

  Therefore, there is a technique for directly detecting the conveyance amount of the recording medium so as not to be affected by variations in the outer diameter of the conveyance roller or eccentricity (Patent Document 1).

  This will be described with reference to FIGS. First, as shown in FIG. 20, the recording apparatus includes a conveyance amount detection sensor unit 701 'at a position facing the recording medium 8 to be conveyed. The transport amount detection sensor unit 701 ′ is provided with a light source 41 that emits light to the surface of the recording medium 8 and a light receiving unit 42 that receives reflected light of the emitted light. As the light receiving unit 42, a line sensor in which photoelectric conversion elements such as a CCD or a CMOS are arranged one-dimensionally, or an area sensor formed by arranging in two dimensions is used. Further, in order to obtain good optical information by the light receiving unit 42, an optical system 43 including a lens is disposed in an optical path from the light source 41 to the light receiving unit 42 through the surface of the recording medium. Further, the transport amount detection sensor unit 701 ′ is provided with hardware 44 that stores and processes image information acquired via the light receiving unit 42.

  Now, the light source 41 emits light to the moving recording medium 8, and the light receiving unit 42 captures the reflected light as image information. The image information here is not particularly limited as long as the surface state of the recording medium can be characterized by reflected light. Here, as shown in FIG. 21A, it is assumed that the first reflected light information 501 from the surface of the recording medium is obtained at an arbitrary time T1. For this image, image information in a specific area (correlation window area) indicated by reference numeral 601 in FIG. 22 is stored as a correlation window pattern 602. Subsequently, as shown in FIG. 21B, second reflected light information 502 is obtained at time T2 different from time T1. Here, in which region of the second reflected light information 502 the correlation window pattern 602 exists is determined by image correlation processing. If the size of the area on the surface of the recording medium imaged by the conveyance amount detection sensor unit 701 ′ is determined in consideration of the optical magnification due to the intervention of the lens or the like, the recording medium is determined from the amount of movement of the matching pattern on the image. Can be detected (FIG. 21C). By directly detecting the actual conveyance amount of the recording medium in this way, the accuracy of conveyance amount detection can be improved, and conveyance control can be performed without being affected by variations in the outer diameter of the conveyance roller or eccentricity.

  However, in order to realize highly accurate conveyance, it is not sufficient to detect the conveyance amount with high accuracy. Even if the conveyance control is performed based on the detection result, the target conveyance amount is not necessarily obtained, and the conveyance roller or the recording medium is targeted by the influence of the reaction force and slip received by the conveyance mechanism from the recording medium. This is because it may not be possible to stop at the position.

JP 2005-82289 A

  Therefore, the present invention realizes recording with good image quality by realizing high-accuracy conveyance stop at the target position in a recording apparatus including a mechanism for directly detecting the conveyance amount of the recording medium using such an optical sensor. The purpose is to be able to perform.

To this end, the present invention provides a recording apparatus that performs recording by conveying a recording medium to a target position.
Using a conveyance unit having a conveyance member that supports and conveys the recording medium, a first conveyance amount detection unit that detects a conveyance amount of the recording medium by detecting a driving amount of the conveyance unit, and an optical sensor And acquiring the image information on the surface of the recording medium or the conveying member at different timings, thereby detecting a change in the position of a specific pattern included in the image information and detecting a conveyance amount of the recording medium. Transport amount detection means, a detection value of the transport amount by the first transport amount detection means obtained with the transport operation of the recording medium to the target position, and a transport amount by the second transport amount detection means Determining means for determining whether the recording medium has reached the target position within an allowable error range by the transport operation based on a difference from the detected value of the target value, and if the arrival is not determined, Carry to position It means for repeatedly performing the acts and the determination, characterized in that comprises a.

The present invention also relates to a transport control method for a recording apparatus that transports a recording medium to a target position and performs recording.
Using a conveyance unit having a conveyance member that supports and conveys the recording medium, a first conveyance amount detection unit that detects a conveyance amount of the recording medium by detecting a driving amount of the conveyance unit, and an optical sensor And acquiring the image information on the surface of the recording medium or the conveying member at different timings, thereby detecting a change in the position of a specific pattern included in the image information and detecting a conveyance amount of the recording medium. And a conveyance amount detection means of
The difference between the detection value of the conveyance amount by the first conveyance amount detection unit obtained by the conveyance operation of the recording medium to the target position and the detection value of the conveyance amount by the second conveyance amount detection unit. Based on this, it is determined whether or not the recording medium has reached the target position within an allowable error range by the transport operation, and if the reach is not determined, the transport operation to the target position and the determination are repeated. It is characterized by executing.

  According to the present invention, in a recording apparatus including a mechanism for detecting a conveyance amount of a recording medium using an optical sensor, high-quality conveyance can be stopped at a target position, thereby recording with good image quality. Will be able to.

1 is a plan view schematically showing a configuration of a main part in an ink jet recording apparatus as an example of a recording apparatus to which the present invention can be applied. FIG. 2 is a schematic perspective view for partially showing a main part structure of a recording head part of a head cartridge applicable to the recording apparatus of FIG. 1. FIG. 2 is a block diagram for explaining a configuration of a control system in the recording apparatus of FIG. 1. FIG. 2 is a schematic side view for explaining a configuration example of a main part of a conveyance system in the recording apparatus of FIG. 1. FIG. 5 is an explanatory view of a light receiving element applied to a transport distance detection unit in the transport system of FIG. 4. (A)-(e) is a typical side view which shows the conveyance state of the recording medium in each timing of the conveyance control process of the recording medium which concerns on the 1st Embodiment of this invention. 3 is a flowchart showing a recording medium conveyance and recording processing procedure according to the first embodiment of the present invention. FIG. 8 is a flowchart illustrating a detection processing procedure of an actual conveyance amount of a recording medium that is employed in the procedure of FIG. (A)-(c) is a figure for demonstrating the image processing at the time of the actual conveyance amount detection of the recording medium based on 1st Embodiment. FIG. 6 is a diagram for explaining image processing when detecting an actual conveyance amount of a recording medium according to the first embodiment. FIG. 6 is a diagram for explaining image processing when detecting an actual conveyance amount of a recording medium according to the first embodiment. FIG. 6 is a diagram for explaining image processing when detecting an actual conveyance amount of a recording medium according to the first embodiment. It is a figure for demonstrating the image process when not using together the 1st conveyance amount detection means. FIG. 6 is an explanatory diagram of recording medium conveyance control according to the first embodiment. 10 is a flowchart illustrating a detection processing procedure for an actual conveyance amount of a recording medium according to a modification of the first embodiment. 10 is a flowchart illustrating a detection processing procedure of an actual conveyance amount of a recording medium according to another modification of the first embodiment. 6 is a flowchart showing a recording medium conveyance and recording processing procedure according to a second embodiment of the present invention. FIG. 10 is an explanatory diagram of recording medium conveyance control according to a second embodiment. FIG. 10 is a schematic side view for explaining another configuration example of the recording apparatus to which the present invention is applicable. FIG. 4 is a schematic side view illustrating a configuration example of a mechanism that detects a conveyance amount of a recording medium using an optical sensor. (A)-(c) is a figure for demonstrating the image processing using the mechanism of FIG. It is a figure for demonstrating the image processing using the mechanism of FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

Basic Configuration FIG. 1 is a plan view schematically showing the configuration of the main part of an ink jet recording apparatus as an example of a recording apparatus to which the present invention is applicable. In FIG. 1, a head cartridge 1 is detachably mounted on a carriage 2. The head cartridge 1 has a recording head portion provided with a plurality of recording elements for ejecting ink, for example, as droplets, and an ink tank portion for replenishing each recording element with ink. Further, the head cartridge 1 is provided with a connector for transmitting and receiving a signal for driving the recording head portion, and the carriage 2 has a connector holder for transmitting a drive signal and the like to the head cartridge 1 via the connector. Is provided.

  Reference numeral 3 denotes a guide shaft installed in the apparatus main body. The carriage 2 is guided and supported by a guide shaft 3 and can reciprocate in the direction indicated by the left and right arrows in FIG. 1 along the direction in which the guide shaft 3 extends. The movement of the carriage 2 is performed by the motor 4 through drive mechanisms such as the motor pulley 5, the driven pulley 6, and the timing belt 7, and the position and the conveyance amount are controlled. Further, the carriage 2 is provided with a home position sensor 30. When the home position sensor 30 passes over the shielding plate 36 at the home position, it can be detected that the carriage 2 is at the home position.

  Before recording is performed, the recording medium 8 is stacked on the auto sheet feeder 32. When recording is started, the paper feed motor 35 is driven, and this driving force is transmitted to the pickup roller 31 via a gear. As a result, the pickup roller 31 rotates, and the recording medium 8 is separated from the auto sheet feeder 32 one by one and fed into the recording apparatus.

  Subsequently, the recording medium 8 is conveyed in a direction indicated by a downward arrow in FIG. 1 at a predetermined speed according to the rotation of the conveying roller 1001 as a conveying member, and passes through a position facing the ejection port surface of the head cartridge 1. The rotation of the conveyance roller 1001 is performed by transmitting the driving force of the conveyance motor 1008 via a gear. Although not shown, apart from the first transport roller 1001, a second transport roller is disposed further downstream (lower side in the figure) than the carriage movement region (described later with reference to FIG. 5). . The second conveying roller also rotates together with the first conveying roller 1001 and conveys the recording medium 8 in cooperation.

  The head cartridge 1 mounted on the carriage 2 has its discharge port forming surface protruding downward from the carriage 2 and held so as to be parallel to the recording medium 8 between the two pairs of transport rollers described above. . Furthermore, the back surface of the recording medium 8 is supported by a platen (not shown) so as to form a flat recording surface in the recording unit. The head cartridge 1 ejects ink to the recording medium 8 in the process of moving together with the carriage 2 in accordance with a predetermined image signal in a state where the recording medium 8 is positioned below the moving region of the carriage 2.

  Reference numeral 33 denotes a paper end sensor capable of confirming the presence or absence of the recording medium 8. When the recording medium 8 is fed, it can be determined whether or not the recording medium 8 has been fed normally by the output of the paper end sensor 33. The timing at which the paper end sensor 33 detects the leading end of the recording medium 8 is also used to determine the recording start position of the fed recording medium 8. Further, by detecting the rear end portion of the recording medium 8 at the final stage of recording, the position of the rear end portion in subsequent recording can be grasped, and the position on the recording medium on which recording is currently performed can be determined. The paper end sensor 33 can be used.

  The head cartridge 1 applied in the present embodiment is an ink jet type head cartridge that discharges ink using thermal energy, and includes a plurality of electrothermal transducers for generating thermal energy. Specifically, thermal energy is generated by a pulse signal applied to the electrothermal transducer, and film boiling occurs inside the ink by this thermal energy, and ink is discharged from the discharge port using the foaming pressure of film boiling. And recording.

  FIG. 2 is a schematic perspective view for partially showing the main structure of the recording head portion 26 of the head cartridge 1 applicable in the present embodiment. In FIG. 2, a plurality of discharge ports 22 are formed at a predetermined pitch on the discharge port forming surface 21 facing the recording medium 8 at a predetermined interval (about 0.5 to 2.0 mm). The discharge ports 22 are formed with liquid passages 24 communicating with the common liquid chambers 23, respectively, and the capillary force forces the ink present in the common liquid chambers to the respective discharge ports. On each wall surface of the liquid passage 24, an electrothermal converter (such as a heating resistor) 25 for generating heat energy is disposed. A predetermined pulse is applied to the electrothermal transducer 25 based on the image signal or the ejection signal, and the heat generated thereby causes film boiling in the ink in the liquid path 24. A predetermined amount of ink is ejected as droplets from the ejection port 22 by the foaming pressure at this time.

  In the present embodiment, a serial type ink jet recording apparatus is applied, and the ejection ports 22 of the head cartridge 1 are arranged in a direction crossing the moving direction of the carriage 2. Then, a recording operation for ejecting ink from each ejection port 22 while moving the carriage 2 and a transporting operation for transporting a predetermined amount of the recording medium in a direction crossing the carriage moving direction are alternately repeated on the recording medium. The image is sequentially formed.

  FIG. 3 is a block diagram for explaining a configuration of a control system in the ink jet recording apparatus applied in the present embodiment. In the figure, a controller 100 is a main control unit of the recording apparatus. The controller 100 includes, for example, a CPU 101 in the form of a microcomputer, a ROM 103 storing programs, required tables, and other fixed data, and a RAM 105 provided with an area for developing image data, a work area, and the like.

  The external apparatus 110 is an apparatus that is connected to the outside of the recording apparatus and serves as an image supply source, and may be a computer that creates and processes data such as images related to recording, a reader unit for image reading, or It may be in the form of a digital camera or the like. Image data, other commands, status signals, and the like supplied from the external device 110 can be transmitted to and received from the controller 100 via the interface (I / F) 112.

  The operation unit 120 is a switch group that receives an input instruction from an operator, and includes a power switch 122, a recovery switch 126 for instructing activation of suction recovery, and the like. The sensor unit 130 is a sensor group for detecting the state of the apparatus. In the present embodiment, in addition to the home position sensor 30 and the paper end sensor 33 described above, a temperature sensor 134, a rotation angle sensor 1006, a conveyance distance detection sensor unit 701, and the like provided for detecting the environmental temperature are included. ing.

  A head driver 140 drives the electrothermal transducer 25 of the recording head 26 in accordance with the recording data. The head driver 140 includes a shift register that aligns recording data corresponding to each of the plurality of electrothermal transducers 25, a latch circuit that latches at appropriate timing, and the electrothermal transducer 25 in synchronization with the drive timing signal. Logic circuit elements to be activated are provided. The head driver 140 further includes a timing setting unit for appropriately setting the ejection timing in order to adjust the dot formation position on the recording medium.

  A sub heater 142 is provided in the vicinity of the recording head 26. The sub-heater 142 adjusts the temperature of the recording head in order to stabilize the ink ejection characteristics. This may be in the form of being formed on the substrate of the recording head 26 as with the electrothermal transducer 25, or in the form of being attached to the main body of the recording head 26 or the head cartridge 1.

  Reference numeral 150 denotes a motor driver for driving the motor 4 that moves the carriage, and reference numeral 170 denotes a motor driver for driving the carry motor 1008. That is, the carriage 2 can move in the main scanning direction by driving the motor 4, and the recording medium 8 is transported in the sub-scanning direction by driving the transport motor 1008. Reference numeral 160 denotes a motor driver for driving the paper feed motor 35, and the recording medium 8 is separated from the autofeet seeder 32 by the drive of the paper feed motor 35 and fed into the recording apparatus.

  FIG. 4 is a schematic side view for explaining a configuration example of a main part of the transport system of the recording apparatus according to the present embodiment. In the figure, reference numeral 1002 denotes a second transport roller disposed on the downstream side of the recording area by the head cartridge 1, and is driven to rotate together with the first transport roller 1001 by a transport motor 1008. Reference numerals 1003 and 1004 denote pinch rollers that are urged against the conveying rollers 1001 and 1002 to sandwich and convey the recording medium 8, respectively.

  Reference numeral 1005 denotes a code wheel fixed on the same rotation shaft as that of the first conveying roller 1001. The code wheel 1005 has slits formed at equal intervals at the circumferential end thereof, and the rotation angle sensor 1006 can detect the position of the slit. The rotation angle sensor 1006 is an optical transmission sensor, and transmits a pulse signal at the timing when a slit is detected. The rotation angle of the code wheel 1005 is detected by the transmitted pulse signal, and the position, velocity, and acceleration of the recording medium 8 are calculated from the time interval at which the pulse signal is transmitted. The code wheel 1005 and the rotation angle sensor 1006 are components of a first conveyance amount detection unit that obtains a detection value of the conveyance amount of the recording medium.

  On the other hand, the transport distance detection unit 701 having the form of an optical sensor that is a component of the second transport amount detection means can directly read the transport distance of the recording medium 8 by the first transport roller 1001 and The ink ejection port array range has a length that encompasses the transport direction. The transport distance detection unit 701 of this example has substantially the same configuration as the unit 701 ′ shown in FIG. 20 and is mounted on the carriage 2 together with the head cartridge 1.

  FIG. 5 is an explanatory diagram of a light receiving element applied to the transport distance detection unit 701. In FIG. 5, reference numeral 1101 denotes the light receiving element 42 mounted on the transport distance detection sensor unit 701, which has the form of an area sensor in which CCD sensors each having a pixel size of 10 μm in length and width are arranged in width 11 × length 20 pixels. is doing. In this example, an optical system 43 having, for example, an optical magnification of 1 including the optical magnification of the lens provided between the light source 41 and the light receiving unit 42 is incorporated, and the surface of the recording medium acquired by one pixel of the sensor The upper size is 10 μm in length and width. Note that “horizontal” corresponds to the moving direction of the head cartridge 1, and the positions in this direction are indicated by reference numerals “1” to “11”. Further, “vertical” corresponds to the conveyance direction of the recording medium 8, and the position in this direction is indicated by the symbols “A” to “T”. The pixel number is indicated as “A row 1 column”.

First Embodiment Referring to FIGS. 6 to 14, a first embodiment in which a first transport amount detection unit including a rotation angle sensor 1006 and a second transport amount detection unit including a transport distance detection unit 701 are used in combination. A form is demonstrated. 6A to 6E are schematic side views showing the conveyance state of the recording medium at each timing of the recording medium conveyance control process according to the first embodiment, and FIGS. It is a flowchart which shows a process sequence. 9 to 12 are diagrams for explaining the image processing in the first embodiment, and FIG. 13 is a diagram for explaining the image processing in the case where the first transport amount detecting means including the rotation angle sensor 1006 is not used together. FIG. Further, FIG. 14 is an explanatory diagram of recording medium conveyance control according to the first embodiment.

  When recording is started, first, feeding of the recording medium 8 is started in step S1 of FIG. At this time, the recording medium 8 is carried in the direction of the arrow in FIG. In step S2, it is determined whether the paper end sensor 33 has detected the leading end of the recording medium 8, and the paper feeding operation is continued until the detection is confirmed. When the leading edge of the recording medium 8 is confirmed in step S2, the process proceeds to step S3, and conveyance control using the rotation angle sensor 1006 is started from this position. This stage corresponds to FIG.

  In step S4, it is determined whether or not the presence of the recording medium 8 is confirmed by the transport distance detection sensor unit 701. Until the confirmation, the conveyance control by the rotation angle sensor 1006 is continued. If the presence of the recording medium 8 is confirmed by the transport distance detection sensor unit 701 in step S4, that is, if it is in the state of FIG. 6C, the process proceeds to step S5. In step S5, the “transport retry count” counter to be used in the subsequent processing is reset to zero.

  In step S6, the processing of “actual conveyance sequence A” shown in FIG. 8 is executed as a sequence for detecting the actual conveyance amount (actual conveyance amount) of the recording medium. In this sequence, first, in step SA1, first image information by reflected light from the recording medium is acquired. The image information is not particularly limited as long as it includes a specific pattern that can characterize the surface state of the recording medium by reflected light. In this example, the image has a cross-shaped pattern recorded in advance on the surface of the recording medium as indicated by reference numeral 1501 in FIG.

  In step SA2 in FIG. 8, an image pattern to be matched in the subsequent image correlation processing is determined. Here, an image in the correlation window region 1502 indicated by hatching in FIG. 9B is stored as a correlation window pattern (matching pattern). The acquisition position of the correlation window is set on the upstream side in the transport direction.

  Next, in step SA3, the designated conveyance amount is conveyed using the rotation angle sensor 1006. Then, in step SA4, second image information by reflected light from the recording medium is acquired. The image information obtained here is the image shown in FIG. Comparing FIG. 9A and FIG. 9C, it can be seen that the position of the acquired image pattern (correlation window pattern) moves (changes) in the recording medium conveyance direction. At the same time, the conveyance amount using the rotation angle sensor 1006 at the time of image acquisition is also calculated and stored. Here, the transport amount calculated and stored from the detection output of the rotation angle sensor 1006 is 120 μm (corresponding to 12 pixels of the sensor), while the actual transport amount of the recording medium is 130 μm (corresponding to 13 pixels of the sensor). Suppose that

  In step SA5, the stored conveyance amount information by the rotation angle sensor is reflected in the image correlation process. In step SA6, an application area of image correlation processing is determined based on the conveyance amount information obtained by the rotation angle sensor. Specifically, since the stored transport amount is 120 μm, the region in the second image information shifted by 120 μm from the correlation window acquisition position in the first image information in the transport direction as shown in FIG. An inclusion area 1603 including 1601 as a center is determined as an image correlation processing range.

  The inclusion area here is determined, for example, from the result of evaluating the conveyance accuracy at the design stage of the printing apparatus. For example, when an evaluation result that a deviation from the actual conveyance amount occurs in a range 1602 of ± 10 μm with respect to the conveyance amount based on the rotation angle sensor is obtained, a region 1603 that sufficiently includes the region is subjected to image correlation processing. Designed as an area. Note that the method of determining the neighborhood region is not limited to this method.

  In step SA7, image correlation processing is performed to determine where the stored correlation window pattern exists in the image correlation processing region. This determination is performed by discriminating a region having a high degree of correlation. As the processing flow, as shown in FIG. 11, for the acquired second image information (FIG. 9C), first, the upper left point of the correlation determination region having the same size as the correlation window (hereinafter, Correlation window starting point) is set to the pixel of B row and 1 column, and the degree of correlation in the correlation determination area is determined. A total of 35 processes are performed while sequentially shifting the correlation window starting point from the pixel in B row 2 column to the pixel in B row 7 column, and then from the pixel in C row 1 column to the pixel in F row 7 column. To do. As a result, the image correlation processing is performed for all the areas of the image correlation processing area 1603, and the degree of correlation in each determination area is calculated.

  In this example, the degree of correlation is determined as the ratio of the number of matching pixels to only the pixels where the pattern exists (5 pixels forming the cross pattern portion). For example, a series of correlation calculation for the C row will be described with reference to FIG. In the region 1801 starting from the pixel in the C row and the first column, there is no matching pixel among the 5 pixels forming the cross pattern portion (matching 0 pixel), and therefore the correlation is 0 pixel / 5 pixel = 0.2. is there. Similarly, in the region 1802 starting from the pixel in C row and 2 column, the correlation is 0.2, the correlation is 0.4 in the region 1803, the correlation is 1.0 in the region 1804, the correlation is 0.4 in the region 1805, and the region 1806. In this case, the correlation degree is 0.2 and the correlation degree is 0 in the area 1807. A region 1804 starting from C row and 4 column having a correlation degree of 1.0 obtains a result having the highest correlation degree in a series of processing of B to F rows, and that area is a movement area of the correlation window pattern. It is determined.

  In this example, the movement destination of the intra-correlation window pattern can be estimated by acquiring the conveyance amount information using the first rotation angle sensor 1006 constituting the first conveyance amount detection unit. The area can be determined easily and quickly. The above image correlation processing is an example, and there is no particular limitation on the method as long as it can be determined where the stored correlation window pattern exists in the image. However, it is difficult to estimate in a system in which the first transport amount detection means is not mounted. In that case, as shown in FIG. 13, an image is displayed for the entire range of the sensor from the determination area having the pixel in the A row and the first column to the correlation window starting point to the determination area having the pixel in the P row and the seventh column starting from the correlation window. Correlation processing needs to be performed. In other words, in order to obtain the same result as in this example, 112 correlation calculations are required, and the processing amount is about three times.

  Now, it can be seen from the processing result of step SA7 that the amount of movement of the correlation window pattern in the transport direction is 13 pixels, so in step SA8 the actual transport amount (actual transport amount) of the recording medium is 13 × 10 μm = It is determined that it is 130 μm, and the processing of “actual conveyance sequence A” is terminated.

  Referring to FIG. 7 again, in step S7, it is determined whether or not the actual transport amount is within the allowable error range of the target transport amount. Considering the case where the target transport amount is 120 μm and the allowable range is ± 5 μm, if the actual transport amount is 130 μm, the allowable range is exceeded, so re-transport (transport retry) to the target stop position is required. It is determined that it needs to be performed, and the process proceeds to step S8.

  In step S8, it is determined whether or not the “transport retry count” counter exceeds a predetermined number. In the subsequent step S9, the “transport retry count” counter is incremented. Next, in step S10, a corrected transport length is calculated based on the difference between the actual transport amount and the target transport amount. If the target transport amount is 120 μm and the actual transport amount is 130 μm as in this example, the difference −10 μm may be used as the corrected transport length, or a value obtained by adding a predetermined numerical value to −10 μm (Adjustment amount) may be used. After calculating the corrected transport amount in step S9, the process returns to step S6, and the actual transport sequence is performed again. That is, by providing a loop of steps S6 to S10, when the transport amount as a result of performing the transport operation is not within the allowable error range of the target transport amount, a transport retry is performed to correct the deviation.

  FIG. 14 is an explanatory diagram of the conveyance control in this embodiment, corresponding to the operation exemplified above, and the horizontal axis indicates the position of the recording medium in the conveyance direction. As a result of carrying out the first conveyance (conveyance (1)) from the illustrated pre-conveyance position, if the target position is not reached within the tolerance range shown in the figure, the second conveyance is carried out from that position. (Transport retry) is performed (transport (2)). In other words, for example, when the first transport with the target transport amount of 120 μm is performed and the actual transport amount is 130 μm and the target transport range is not within ± 5 μm, the transport with the difference of −10 μm as the target value is performed. Retry (reverse conveyance of 10 μm) is performed. If it still does not fall within the target allowable range, the conveyance retry is performed again from that position (conveyance (3)). By repeating the transport retry in this way, even if the target transport amount cannot be realized at the beginning, the target transport amount can be approached while the transport retry is repeated.

  The permissible range may be set according to the transport amount, and it is preferable to decrease the permissible range as the transport amount is small. This is because if the allowable range is set large when the transport amount is small, the cumulative amount of errors resulting from the repeated transport of the small transport amount increases, and this affects the size of the completed image. This is because there is a risk of causing it. If the number of conveyance retries increases, it takes time to form an image. Therefore, as shown in step S8, if the number of conveyance retries exceeds a predetermined number, the conveyance retries are not performed. can do. Thereby, it is possible to suppress a decrease in recording throughput due to an increase in the number of conveyance retries.

  If it is determined in step S7 in FIG. 7 that the sheet has been transferred to the target transfer position, the process proceeds to step S11, and the “transfer retry count” counter is reset to zero. Next, in step S12, recording at the target transport position is performed by moving the head cartridge 1. In step S13, it is determined whether the image of the page being recorded has been completed. If the determination is negative, the process returns to step S6 and the subsequent processing is repeated. That is, conveyance is performed to the next target conveyance position while performing conveyance retry as necessary, and recording is performed. On the other hand, if an affirmative determination is made in step S13, the process proceeds to step S14, the paper is discharged, and the sequence is terminated. FIGS. 6D and 6E respectively show the conveyance state of the recording medium when the image is not completed and the discharge state when the image is completed.

Modified Example of First Embodiment In the above embodiment, the case where the detection area of the correlation window pattern falls within the range of the second image information as a result of conveying the recording medium by the specified amount and stopping is described. However, in reality, the designated recording medium conveyance amount is large, and as a result of the conveyance being stopped by the designated amount, the pattern in the correlation window may be out of the range of the second image information. Therefore, as a modification of the first embodiment, a configuration for dealing with such a case will be described.

  FIG. 15 shows a sequence corresponding to this configuration, which can be used in place of the “actual transport sequence A” (FIG. 8) in step S6 of FIG. That is, after the “transport retry count” counter is reset to zero in step S5 of FIG. 7, the processing of “actual transport sequence B” is performed as the actual transport amount detection sequence corresponding to this example.

  In step SB1, as in step SA1 in FIG. 8, first image information such as an image 1501 in FIG. 9A is acquired by reflected light from the recording medium. Then, similarly to step SA2, the correlation window pattern is determined and stored (step SB2).

  Next, in step SB3, the designated conveyance amount using the rotation angle sensor 1006 is started. Then, during the conveyance process, the second image information is acquired at a timing when the moving correlation window pattern exists within the imaging range of the sensor unit 701, while the rotation angle sensor conveys the conveyance amount information at the time of acquisition. Is stored (step SB4). In steps SB5 to SB7, similarly to steps SA5 to SA7, the conveyance amount information obtained by the rotation angle sensor is reflected in the image correlation process, the application area of the image correlation process is determined, and the image correlation process is performed.

  In step SB8, the conveyance amount by the series of processing of step SB3 to step SB7 is calculated and stored from the processing result of step SB7. In this example, the image information is acquired or the transport amount is calculated at a sufficiently short time interval in which the moving correlation window pattern exists within the imaging range (detection length) of the sensor unit. Then, this is repeated a plurality of times from the start to the completion of one transfer, and the total of the plurality of transfer amounts calculated from the start to the completion of one transfer is obtained to obtain a single transfer amount. Ask for. If it is determined by the rotation angle sensor that the specified amount of conveyance has not yet been completed, the correlation window pattern is extracted from the second image information acquired in step SB4 at the previous timing and stored ( Step SB11). Then, after the image information including the correlation window pattern is set as the first image information, the process returns to Step SB3, and Steps SB3 to SB8 are repeated until the predetermined number of processes are completed. That is, image correlation processing and conveyance amount acquisition are performed for the patterns in the correlation window between successive timings.

  When the designated amount of conveyance is completed by the rotation angle sensor, in step SB10, the conveyance amounts stored in step SB8 are added, and the actual conveyance amount is determined (estimated). Then, after the above “actual conveyance sequence B” is completed, the process proceeds to step S7 in FIG. 7, and thereafter, the same processing as in the above example is performed.

  In the first embodiment and the modified example thereof, when the detection area of the correlation window pattern falls within the range of the second image information when the recording medium is transported by the specified amount and stopped, respectively. Explained. However, there are cases where various amounts of conveyance are performed for setting the image recording position, and both cases may be mixed. Therefore, a configuration for dealing with this will be described as another modification of the first embodiment.

  FIG. 16 shows a sequence corresponding to the configuration, which can be used in place of the “actual conveyance sequence A” (FIG. 8) in step S6 of FIG. That is, after the “transport retry count” counter is reset to zero in step S5 in FIG. 7, the processing of “actual transport sequence C” is performed as the actual transport amount detection sequence corresponding to this example. In step SC1, as in step SA1 in FIG. 8, first image information such as an image 1501 in FIG. 9A is acquired by reflected light from the recording medium. Then, similarly to step SA2, the correlation window pattern is determined and stored (step SC2).

  Next, in this example, in step SC3, whether or not the correlation window pattern that moves as a result of the designated amount of conveyance is within the imaging range of the sensor unit, that is, whether the designated conveyance amount is longer than the detection length of the sensor unit. It is judged whether it is short. If it is determined in step SC3 that the detection length is longer than the designated transport amount (the moving correlation window pattern is within the imaging range of the sensor unit), the process proceeds to step SC4, and “actual” as in the first embodiment is performed. Carrying sequence “A” is performed. On the other hand, if the detected length is equal to or smaller than the designated transport amount, the process proceeds to step SC5, and the “actual transport sequence B” similar to the above-described modification is performed. Then, after step SC4 (the process of “actual transport sequence A”) or step SC5 (the process of “actual transport sequence B”) is completed, the process proceeds to step S7 in FIG. 7, and thereafter, the same process as in the first embodiment is performed. To implement.

Second Embodiment In the first embodiment, when the transport amount as a result of performing the transport operation is not within the allowable range of the target transport amount, re-conveyance for the deviation (in the direction opposite to the previous transport) The sequence for keeping the transport amount within the allowable range while performing the transport) has been described. On the other hand, in the second embodiment, when the transport amount is not within the allowable range with respect to the target transport amount, after the transport that returns by a relatively large predetermined amount with respect to the deviation is performed once. The transportation retry is performed from that position to the target transportation position.

  FIG. 17 is a flowchart showing a processing procedure according to the present embodiment, and FIG. 18 is an explanatory diagram of recording medium conveyance control according to the second embodiment. The procedure in FIG. 17 basically employs the same steps S1 to S14 as in FIG. 7, but the following steps S8-2 and S8-3 are interposed between steps S8 and S9. The point is different.

  In other words, if a negative determination is made as a result of performing step S8 for determining whether the “conveyance retry count” counter has exceeded a predetermined number of times, the process proceeds to step S8-2 and a relatively large return conveyance amount (for example, about −1000 μm). ). Next, in step S8-3, the process of “actual conveyance sequence A” as shown in FIG. 8 is executed for the return conveyance. In the subsequent step S9, the “conveyance retry count” counter is incremented, and in step S10, a corrected conveyance length is calculated based on the difference between the actual conveyance amount and the target conveyance amount. The transport correction length is obtained by executing the actual transport sequence in step S8-3 and the deviation of the actual transport amount in the initial transport obtained by performing the actual transport sequence in step S6 from the target transport amount. It is calculated based on the actual transport amount at the time of return transport. For example, if the former (deviation of the actual transport amount during the initial transport relative to the target transport amount) is +10 μm and the latter (actual transport amount during the return transport) is −1000 μm, the value obtained by adding these two values A value obtained by reversing the sign (+990 μm) may be used as the corrected conveyance length. Alternatively, the conveyance correction amount may be a value obtained by adding a predetermined numerical value to two numerical values. After calculating the corrected transport amount in step S9, the process returns to step S6, and the actual transport sequence is performed again. That is, by providing a loop of steps S6 to S10 including steps S8-2 and S8-3, if the transport amount as a result of performing the initial transport operation is not within the allowable range of the target transport amount, After carrying out a predetermined amount of return conveyance, a conveyance retry is performed to correct the deviation.

  FIG. 18 is an explanatory diagram of the conveyance control in the present embodiment, corresponding to the operation exemplified above, and the horizontal axis indicates the position of the recording medium in the conveyance direction. If the result of the first transfer (transfer (1)) from the illustrated pre-transfer position does not fall within the target tolerance shown in the figure, a predetermined amount of return transfer from that position is once performed. I do. Further, a transport retry is performed from that position (transport (2)). If it still does not fall within the target allowable range, after a predetermined amount of return conveyance is performed again, a conveyance retry is further performed (conveyance (3)) to approach the target conveyance amount.

  As described above, in the present embodiment, when the transport amount is not within the allowable range of the target transport amount as a result of performing the transport operation, a predetermined amount of return transport is once performed before the transport retry. If the transport retry to the target position (transport in the reverse direction) is performed by the method of the first embodiment when the transport allowable range is set to be narrow, the transport amount to be performed by the transport retry becomes small. Generally, since the operation of the motor is not stable unless a certain amount of conveyance is performed in the control of the conveyance roller, there is a possibility that the stop accuracy may not be stable in the conveyance retry performed in the first embodiment. On the other hand, as in this embodiment, before carrying out the conveyance retry to the target position, it is more effective to carry out the return conveyance with a large conveyance amount to the extent that the operation of the motor is stable and the stop accuracy can be expected. Thus, it becomes possible to approach the target transport position.

  Note that the present embodiment can be modified in the same manner as in the first embodiment. That is, as a result of carrying the specified amount, there are cases where the detection area of the correlation window pattern is out of the range of the second image information, and the detection area is out of the range of the second image information. It is possible to configure two modified examples considering each case.

Others In the above examples, the first transport amount detection means is in the form of a rotary encoder including a code wheel and an optical rotation angle sensor, but is not particularly limited as long as the transport amount can be detected. For example, if a stepping motor is used to drive the recording medium conveying means, the driving amount, that is, the conveying amount can be detected from the number of driving pulses.

  In each of the above examples, the information detected by the transport distance detection sensor unit constituting the second transport amount detection means is a pattern recorded in advance on the surface of the recording medium. In this case, it is strongly desirable that the pattern is recorded in a portion (for example, a side end portion of the recording medium) or a color tone that does not affect the recording quality. Furthermore, the shape of the specific pattern used for detecting the actual transport amount is not limited to the above example, and may not be recorded in advance. For example, it may be a shadow appearing due to the surface shape, a speckle pattern generated by interference of reflected light from a coherent light source, or the like. That is, this information is not particularly limited as long as it can characterize the surface state of the recording medium by reflected light.

  Further, instead of detecting information for acquiring the actual transport distance from the recording medium, the information may be detected from the transport member itself. For example, as shown in FIG. 19, when a belt conveyance mechanism that conveys the recording medium 8 together with the recording medium support belt in a state where the recording medium 8 is supported by an endless recording medium support belt 1200 is used, the conveyance distance detection sensor unit 701 causes the belt to be You may make it detect a surface state. The second conveyance amount detection unit may detect the recording medium support surface. When the present invention is applied to the belt conveyance mechanism as shown in FIG. 19, the electrostatic force that prevents the recording medium from slipping or floating on the belt can be detected correctly as the conveyance amount of the belt. It is desirable to apply an adsorption mechanism or the like.

  In addition, the arrangement position of the conveyance distance detection sensor unit 701 can be appropriately determined as long as the information for obtaining the actual conveyance distance can be detected from the surface of the conveyance member such as a recording medium or a belt. is there.

8 Recording medium 701 Conveyance distance detection sensor unit 1006 Rotation angle sensor unit 1001, 1002 Conveyance roller 1200 Recording medium support belt

Claims (5)

In a recording apparatus for recording by conveying a recording medium to a target position,
Transport means having a transport member for supporting and transporting the recording medium;
First transport amount detection means for detecting the transport amount of the recording medium by detecting the drive amount of the transport means;
By acquiring image information on the surface of the recording medium or the conveying member at different timings using an optical sensor, a change in the position of a specific pattern included in the image information is detected, and the conveyance amount of the recording medium is determined. Second transport amount detection means for detecting;
The difference between the detection value of the conveyance amount by the first conveyance amount detection unit obtained by the conveyance operation of the recording medium to the target position and the detection value of the conveyance amount by the second conveyance amount detection unit. A determination unit for determining whether or not the recording medium has reached the target position within a tolerance range by the transport operation;
If the arrival is not determined, means for repeatedly performing the transport operation to the target position and the determination;
A recording apparatus characterized by comprising:   2. The recording apparatus according to claim 1, wherein when the arrival is not determined, a transport operation to the target position is performed in consideration of an adjustment amount corresponding to the difference.   3. The recording apparatus according to claim 1, wherein when the number of repetitions exceeds a limited number, the repetition is terminated and a recording operation is performed.   The recording apparatus according to claim 1, wherein the range of the allowable error varies depending on a conveyance amount to the target position. In a conveyance control method of a recording apparatus that conveys a recording medium to a target position and performs recording,
Using a conveyance unit having a conveyance member that supports and conveys the recording medium, a first conveyance amount detection unit that detects a conveyance amount of the recording medium by detecting a driving amount of the conveyance unit, and an optical sensor And acquiring the image information on the surface of the recording medium or the conveying member at different timings, thereby detecting a change in the position of a specific pattern included in the image information and detecting a conveyance amount of the recording medium. And a conveyance amount detection means of
The difference between the detection value of the conveyance amount by the first conveyance amount detection unit obtained by the conveyance operation of the recording medium to the target position and the detection value of the conveyance amount by the second conveyance amount detection unit. And determining whether the recording medium has reached the target position within an allowable error range by the transport operation,
When the arrival is not determined, the conveyance operation to the target position and the determination are repeatedly executed.
The conveyance control method characterized by the above-mentioned.

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