JP5948799B2 - Medium transport apparatus, recording apparatus, and medium transport control method - Google Patents

Description

  The present invention relates to a medium transport apparatus, a recording apparatus, and a medium transport control method for controlling the transport amount of a medium such as paper used for printing.

  For example, Patent Document 1 discloses an image forming apparatus including a conveying device that conveys a medium (recording medium) such as paper, and a recording unit such as a recording head (printing head) that performs recording on the medium conveyed by the conveying device. Is disclosed.

  The image forming apparatus emits a coherent light beam to a surface that moves as the paper is conveyed, and receives a reflected light of the light beam to generate a paper position signal related to the paper position. A detection means is provided. Further, the image forming apparatus calculates a paper conveyance amount calculation value corresponding to a distance that the paper is conveyed within each unit driving time by comparing the paper position signals in time series. A sheet conveyance amount calculation unit is provided. Then, the paper is conveyed using a driving source driven at a predetermined driving speed for each predetermined time interval.

  Furthermore, a sheet conveyance amount determination unit that determines whether the calculated value of the sheet conveyance amount is within a predetermined normal range for each unit driving time is provided. In addition, when the paper conveyance amount determination unit determines that the paper conveyance amount calculation value is within the normal range, the paper conveyance amount calculation value is used as the paper conveyance amount control value for the corresponding unit driving time, and the movement amount detection is performed. When it is determined that the value is out of the normal range, a sheet conveyance amount control value setting unit is provided which sets a preset reference conveyance amount as a sheet conveyance amount control value in the corresponding unit driving time. Further, the image forming apparatus includes a time segment setting unit that sets the time segment based on the cumulative value of the sheet conveyance amount control value. Then, the paper is conveyed for each time segment.

Japanese Patent Laying-Open No. 2003-267591 (for example, paragraphs [0078] and [0083], FIG. 5)

  By the way, in the image forming apparatus described in Patent Document 1, when the paper transport amount calculation value is calculated as a value far from the actual paper transport amount for some reason, the paper transport amount control value is set in advance. Since it is set based on the reference transport amount, it does not differ greatly from the actual paper transport amount, but correction that reflects the detection result of the paper position signal detection means cannot be performed. For this reason, the accuracy of the conveyance amount by which the sheet is conveyed is not sufficient.

The present invention has been made in view of the above problems, and an object thereof is, even when the detection amount of movement is normally outside the scope Ru detection miss occurs, represented by the accumulated value of the detected movement amount actual the conveyance amount, can in obtained as a relatively suitable value information is reflected on the position of the medium detected by the detecting means, and thus the medium conveying device capable of increasing the accuracy of the transfer position of the medium, the medium conveyance control method, and recording To provide an apparatus.

In order to achieve the above object, one aspect of the present invention is a medium conveying apparatus, a conveying means for conveying a medium, a first detecting means for detecting a driving amount of the conveying means, and the first A control unit that controls the transport unit based on a detection result of the detection unit to transport the medium by a target transport amount; a second detection unit that detects information related to a position of the medium transported by the transport unit; A movement amount acquisition means for acquiring the detected movement amount of the medium for each unit driving time by comparing the information on the position detected by the second detection means in order of time series, and the transport When the means transports the medium so that the theoretical movement amount per unit driving time corresponds to a preset acceleration / deceleration profile, the control means, when the detected movement amount is within a normal range, ,Previous The detection movement amount added, the detection when the displacement is outside the normal range, the detected that were within the normal range in at least one unit drive time of the front and rear of the normal range in a units driving time Interpolated based on the movement amount and the ratio of the theoretical movement amount of a plurality of unit drive times including the unit drive time outside the normal range and at least one unit drive time before and after the unit drive time. By adding the interpolated movement amount in the unit driving time as the detected movement amount, an actual conveyance amount given as an accumulated value of the detected movement amount for each unit driving time is obtained, and the actual conveyance amount and the target conveyance amount are obtained. The gist is to correct the next target transport amount based on the difference.
In order to achieve the above object, one aspect of the present invention is a medium conveying apparatus, a conveying means for conveying a medium, and a detecting means for detecting information relating to the position of the medium conveyed by the conveying means. A movement amount calculating means for calculating a calculated movement amount of the medium for each unit driving time by comparing the information detected during a predetermined transport time by the detection means in order of time series; and the unit A determination unit that determines whether or not the calculated movement amount is within a normal range for each driving time; and when the determination unit determines that the calculated movement amount is within the normal range, the calculation The movement amount is a movement amount control value in the corresponding unit driving time, and when it is determined that the calculated movement amount is outside the normal range, it is within the normal range during the predetermined conveyance time. Determined calculation A setting unit that sets a value calculated based on the movement amount as a movement amount control value in a corresponding unit driving time; a control unit that controls the conveyance amount of the medium by the conveyance unit based on the movement amount control value; It is a summary to provide.

  According to the above configuration, the movement amount calculation unit calculates the calculated movement amount of the medium for each unit driving time by comparing information detected during the predetermined conveyance time by the detection unit in order of time series. The determination unit determines whether or not the calculated movement amount is within a normal range for each unit driving time. When the determining means determines that the calculated movement amount is within the normal range, the setting means uses the calculated movement amount as a movement amount control value for the corresponding unit driving time, and the calculated movement amount is outside the normal range. If it is determined that there is a value, the value calculated based on the calculated movement amount determined to be within the normal range during the predetermined transport time is set as the movement amount control value for the corresponding unit driving time. The control unit controls the conveyance amount of the medium by the conveyance unit based on the movement amount control value. Therefore, when a calculation error occurs when the calculated movement amount is determined to be out of the normal range, a relatively appropriate calculated movement amount that reflects information on the position of the medium detected by the detection unit during a predetermined conveyance time is moved. It can be set as a quantity control value. As a result, the accuracy of the transport amount for transporting the medium (that is, the position of the medium after transport) can be improved.

  In the medium transport apparatus according to one aspect of the present invention, the setting unit determines that the setting movement amount is out of the normal range when the calculated movement amount is determined to be out of the normal range. A value calculated based on the calculated movement amount determined to be within at least one of the normal ranges before and after the unit driving time corresponding to the movement amount is set as a movement amount control value for the corresponding unit driving time. preferable.

  According to the above configuration, when a calculation error occurs when the calculated movement amount is determined to be out of the normal range, at least one normal time before and after the unit driving time corresponding to the calculated movement amount determined to be out of the normal range. A value calculated based on the calculated movement amount determined to be within the range is set as the movement amount control value for the corresponding unit driving time. Since this movement amount control value is based on at least one normal calculated movement amount before and after the unit driving time corresponding to the calculated movement amount determined to be outside the normal range, a more appropriate movement amount control value is set. Can be set.

  In the medium transport apparatus according to one aspect of the present invention, the transport unit is configured to transport the medium based on a speed profile including three speed regions, an acceleration region, a constant speed region, and a deceleration region, When it is determined that the calculated movement amount is outside the normal range, the setting means belongs to the same speed region as the unit driving time corresponding to the calculated movement amount and is at least before and after the unit driving time. A value calculated based on the calculated movement amount determined to be within one of the normal ranges is preferably used as the movement amount control value.

  According to the above configuration, the movement amount control value is calculated based on the calculated movement amount determined to be within the normal range belonging to the same speed region as the unit driving time corresponding to the calculated movement amount determined to be out of the normal range. Therefore, an appropriate movement amount control value can be set when a calculation error occurs.

  In the medium conveying apparatus according to one aspect of the present invention, when the conveying unit conveys the medium so that the moving amount per unit driving time is constant, the setting unit has the calculated moving amount If it is determined that the calculated movement amount is outside the normal range, an average value of the calculated movement amounts determined to be within the normal range before and after the unit driving time corresponding to the calculated movement amount is set to the corresponding unit driving time. It is preferable to set the movement amount control value at.

  According to the above configuration, when a calculation error occurs in the constant speed region in which the conveyance unit conveys the medium so that the movement amount per unit driving time is constant, it corresponds to the calculated movement amount determined to be out of the normal range. A movement amount control value is calculated based on the calculated movement amount determined to be within the normal range before and after the unit driving time. Therefore, an appropriate transport control value can be set when a calculation error occurs in the constant speed region.

In the medium conveying apparatus which is one aspect of the present invention, when the conveying unit conveys the medium such that the movement amount per unit driving time corresponds to a preset acceleration / deceleration profile,
The setting means, when it is determined that the calculated movement amount is outside the normal range, at least one of before and after a unit drive time corresponding to the calculated movement amount determined to be outside the normal range It is preferable that a value calculated based on the calculated movement amount determined to be within the normal range and the acceleration / deceleration profile be the movement amount control value.

  According to the above configuration, when a calculation error occurs in the acceleration / deceleration region of the medium, the medium is within at least one normal range before and after the unit driving time corresponding to the calculated movement amount determined to be out of the normal range. Based on the calculated movement amount and acceleration / deceleration profile determined as above, the movement amount control value for the corresponding unit driving time is calculated. Since this movement amount control value is based on the acceleration / deceleration profile, a more appropriate movement amount control value can be set.

  One aspect of the present invention is a recording apparatus comprising the above-described medium conveying apparatus and recording means for recording on a medium conveyed by the medium conveying apparatus. According to the above configuration, since the invention relating to the medium conveying apparatus is included, the accuracy of the conveying amount of the medium on which the recording is performed can be improved, and the medium can be conveyed with high positional accuracy.

One aspect of the present invention is a medium transport control method, the first detection step for detecting a driving amount of a transport unit for transporting a medium, and the transport based on a detection result in the first detection step. A control step for controlling the means to transport the medium by a target transport amount, a second detection step for detecting information relating to the position of the medium transported by the transport means, and a second detection step. A movement amount acquisition step of acquiring the detected movement amount of the medium for each unit driving time by comparing the information on the position in time-series order, and in the control step, the transport means includes the unit driving when the theoretical amount of movement per time transports the medium so as to correspond to the acceleration and deceleration profile which is set in advance, when the detected amount of movement is within the normal range, the test The amount of movement is added, wherein when detecting movement amount the normal range, the were within the normal range in at least one unit drive time of the front and rear of the normal range in a units drive time detected movement and quantity, corresponding to interpolate based on the ratio of the theoretical amount of movement of a plurality of unit driving time and at least one of the unit drive time of before and after the a units drive time in a normal range and the unit drive time By adding the interpolated movement amount in the unit driving time as the detected movement amount, an actual conveyance amount given as an accumulated value of the detected movement amount for each unit driving time is obtained, and the actual conveyance amount and the target conveyance amount are obtained. The gist is to correct the next target transport amount based on the difference.
One aspect of the present invention is a medium transport control method, wherein a transport step for transporting a medium, a detection step for detecting information on a position of the transported medium, and a predetermined transport by the detection step. A movement amount calculating step for calculating a calculated movement amount of the medium for each unit driving time by comparing the information detected during time in order of time series, and the calculated movement amount for each unit driving time. A determination step for determining whether the calculated movement amount is within the normal range, and a determination unit that determines whether or not the calculated movement amount is within the normal range. If the calculated movement amount is determined to be outside the normal range, the calculated movement amount is determined to be within the normal range during the predetermined transport time. And a control step for controlling the transport amount of the medium by the transport unit based on the travel amount control value. And According to the said method, the effect similar to the invention which concerns on a medium conveying apparatus can be acquired.

1 is a perspective view of a printer according to an embodiment. The schematic side view which shows the principal part of a conveying apparatus. FIG. 3 is a schematic side sectional view of an imaging unit. (A), (b) is explanatory drawing of a template matching process. FIG. 3 is a block diagram illustrating an electrical configuration of the printer. The block diagram which shows the function structure of a conveying apparatus. A graph that describes the reference data. The flowchart which shows a movement amount calculation process routine. The flowchart which shows a conveyance control routine.

Hereinafter, an embodiment in which a recording apparatus including a medium conveying apparatus of the present invention is embodied in an ink jet printer will be described with reference to FIGS.
As shown in FIG. 1, an ink jet printer (hereinafter simply referred to as “printer 11”), which is an example of a recording apparatus, automatically feeds paper P, which is an example of a medium, to the back side of a main body 12. A paper device 13 (Auto Sheet Feeder) is installed. A paper guide 17 including a paper feed tray 14, a hopper 15, an edge guide 16, and a paper support 14a is attached to the automatic paper feeder 13. The automatic paper feeder 13 feeds the paper set in the paper guide 17 into the main body 12 one by one.

  A carriage 18 that reciprocates in the main scanning direction (X direction in FIG. 1) is provided in the main body 12, and a recording head 19 is attached to the lower portion of the carriage 18. The printer 11 performs a printing operation of ejecting ink droplets from the recording head 19 onto the surface of the paper P in the process of moving the carriage 18 in the main scanning direction X, and a predetermined transport amount of the paper P in the sub-scanning direction Y (transport direction). By alternately repeating the paper feeding operation carried in step 1, an image based on the given print data is printed on the paper P. The printed paper P is discharged from a paper discharge port 12 </ b> A that opens at the lower front side of the main body 12. The carriage 18 and the recording head 19 constitute an example of a recording unit.

  As shown in FIG. 2, the hopper 15 is supported on the upper surface side of the paper feed tray 14 disposed obliquely on the back surface of the main body so as to tilt within a predetermined angle range about the shaft 15a at the upper end. Has been. The hopper 15 is urged in a direction away from the paper feed tray 14 (upper left direction in FIG. 2) by a compression spring 21 interposed between the paper feed tray 14.

  In the vicinity of the lower end of the hopper 15, a cylindrical sheet feeding roller 22 is disposed so as to be rotatable about a rotation shaft 23. A retard roller 24 is disposed below the paper feed tray 14 at a position facing the paper feed roller 22. The hopper 15 and the retard roller 24 move in conjunction with each other, and are respectively disposed at the paper feed position shown in FIG. 2 and the retreat position moved from the paper feed position to the side away from the paper feed roller 22. The paper feed roller 22 is driven by a feed motor 72 (see FIG. 5), and the hopper 15 and the retard roller 24 are driven by a sub motor 73 (see FIG. 5).

  As shown in FIG. 2, at a position downstream of the automatic paper feeder 13 in the transport direction Y of the paper P, the carriage 18 on which the ink cartridge 26 is mounted is moved along the guide shaft 27 in the main scanning direction X (the paper surface of FIG. 2). It is provided so as to be movable in the (perpendicular direction). The back portion (right side portion in FIG. 2) of the carriage 18 is an endless timing belt 29 wound around a pair of pulleys 28 (only one is shown in FIG. 2) arranged at a predetermined distance in the main scanning direction X. It is fixed to a part of. As the timing belt 29 is driven forward and backward, the carriage 18 reciprocates in the main scanning direction X. Below the recording head 19 attached to the lower portion of the carriage 18, a support base 30 that defines the interval between the recording head 19 and the paper P is in the main scanning direction over a range slightly longer than the assumed maximum width of the paper P. It arrange | positions so that it may extend to X.

  On both sides of the support table 30 in the transport direction Y, a transport roller pair 31 (paper feed roller pair) and a paper discharge roller pair 32 are arranged. The transport roller pair 31 is composed of a pair of a transport drive roller 31a and a transport driven roller 31b, and the paper discharge roller pair 32 is composed of a pair of a paper discharge drive roller 32a and a paper discharge driven roller 32b. In the present embodiment, the transport driving roller 31a and the paper discharge driving roller 32a are driven by a transport motor 74 (see FIG. 5) that is the same power source. An optical paper detection sensor 33 that can detect the leading edge of the paper P is provided between the paper feed roller 22 and the transport roller pair 31.

  When the printing shown in FIG. 2 is performed, the retard roller 24 and the hopper 15 are arranged at the paper feeding position shown in FIG. 2, and when the paper feeding roller 22 rotates in this state, the uppermost of the papers P stacked on the hopper 15. Only one of these is fed. Even during printing of the preceding paper P1, the succeeding paper P2 is fed while ensuring a predetermined distance from the preceding paper P1 by the rotation of the paper feed roller 22.

  The fed paper P1 passes between the pair of transport rollers 31 and is cued to the printing start position while being held on the upper surface of the support base 30. Then, the printing operation of the recording head 19 and the paper feeding operation are alternately performed, and the printing on the paper P is advanced. At this time, the paper P slightly slips between the transport roller pair 31 and the paper discharge roller pair 32 during the printing operation. In this case, the target transport amount for transporting the paper P to the next recording position and the actual transport amount actually transported until the paper P stops at the next recording position are slightly different by the amount of slippage. Yes. For this reason, in the present embodiment, feedback control of the transport operation in which the actual transport amount of the paper P is detected, feedback correction is performed based on the detected actual transport amount and the target transport amount, and the next target transport amount is set. Do.

  In the present embodiment, in order to detect the actual transport amount of the paper P, as shown in FIG. 2, an imaging unit 40 as an example of a detection unit that images the back surface of the paper P from below is arranged on the support base 30. Has been. The image pickup unit 40 picks up the texture (paper pattern) of the paper P, compares the texture images picked up at regular time intervals (unit drive time) two by two before and after in chronological order. This is used to calculate the amount of movement of P per unit driving time. Then, by accumulating (accumulating) the movement amount of the sheet P per unit driving time, the actual conveyance amount actually conveyed in one conveyance operation of the sheet P is measured. This actual transport amount is compared with the target transport amount at that time, and correction for bringing the actual transport amount closer to the target transport amount is performed when the next target transport amount is determined.

  As shown in FIG. 3, a detection window hole 30b is formed in the support base 30 at a position where the paper P of all sizes having the minimum width to the maximum width passes through the holding surface 30a on which the paper P is held. Yes. The imaging unit 40 includes a case 42 having a shape having a truncated cone-shaped portion with a translucent glass 41 attached to the tip (upper end) at the top. The imaging unit 40 is in a state in which the translucent glass 41 is fitted in the hole 30b of the support base 30, for example, in a state of being fitted in an assembly hole (not shown) formed in the lower end portion of the support base 30. It is assembled to the support base 30.

  As shown in FIG. 3, in the case 42, the light emitting portion 43 is fixed to the inner wall surface of the case 42 through a support bracket (not shown) at an angular posture capable of emitting light toward the translucent glass 41. Yes. The light emitting unit 43 is made of, for example, a light emitting diode (LED). In the case 42, the light emitted from the light emitting unit 43 and transmitted through the light transmitting glass 41 is reflected by the back surface of the paper P, and is reflected through the light transmitting glass 41 again and enters the case 42. A condensing lens 44 for condensing light is disposed. Furthermore, an imaging element 45 having an imaging surface 45 a on which an image (texture image) of the back surface of the paper P condensed by the condenser lens 44 is formed in the case 42. The imaging element 45 is configured by a two-dimensional image sensor (area sensor), for example, and can capture a texture image (video) on the back surface of the paper P. The condenser lens 44 is held via a holding member 46 at a height at which an image of the back surface of the paper P can be formed on the imaging surface 45 a of the imaging element 45.

  Next, the electrical configuration of the printer will be described with reference to FIG. As shown in FIG. 5, the printer 11 includes a control device 50 (controller) that performs various controls including conveyance control and print control. The control device 50 includes a computer 51, a communication interface (hereinafter referred to as “communication I / F 52”) that is communicably connected to a host device (not shown), a head driver 53, and motor drivers 54 to 57. Yes.

  Connected to the bus 58 connected to the communication I / F 52 are a CPU 60, an ASIC 61 (Application Specific IC (IC)), a ROM 62, a RAM 63, a non-volatile memory 64, and the like, which constitute a computer 51 (microprocessor). ing.

  The nonvolatile memory 64 stores a program PR necessary for the printing process, including a movement amount calculation processing routine shown in the flowchart in FIG. 8 and a conveyance control routine shown in the flowchart in FIG. The CPU 60 executes a program PR to perform paper feed control, transport control, print control, paper discharge control, and the like. Among these, the transport speed (paper P) is controlled by referring to the transport speed control data when the transport control is executed. Paper feed speed). The nonvolatile memory 64 also includes reference data RD shown in the graph of FIG. 7 used in the movement amount calculation processing routine, and speed control data VD used to transport the paper P with a predetermined speed profile. It is remembered. The speed control data VD is composed of a speed control table indicating the correspondence between each transport position and each transport speed (for example, a speed command value) in the acceleration region and the deceleration region in one transport operation. The speed control data VD is prepared for each different target speed (constant speed). Details of the reference data RD will be described later.

  The CPU 60 inputs print data received by the communication I / F 52 from a printer driver (not shown) built in the host device through the bus 58. Then, the CPU 60 interprets a command in the print data, and performs transport control such as paper feed / transport (paper feed) / discharge and the movement control of the carriage 18 according to the interpreted command.

  The ASIC 61 receives print image data out of the print data from the CPU 60, and performs predetermined image processing including a process of rearranging dots in accordance with the nozzle arrangement order of the recording head 19 to obtain the head control data. The acquired head control data is sent to the head driver 53. The head driver 53 controls the drive circuit in the recording head 19 based on the head control data to eject ink droplets from the nozzles for which dots have been selected.

  The CPU 60 is electrically connected to the carriage motor 71, the feed motor 72, the sub motor 73, and the transport motor 74 via the motor drivers 54 to 57. The CPU 60 drives the carriage motor 71 forward / reversely via the motor driver 54 and rotates the driving pulley 28 connected to the output shaft forward / reversely to rotate the timing belt 29 (see FIG. 2). By reversing, the carriage 18 is reciprocated in the main scanning direction X. Ink droplets are ejected from the recording head 19 in accordance with the timing during the movement of the carriage 18.

  The CPU 60 drives the feed motor 72 via the motor driver 55 and feeds the paper P by rotating the paper feed roller 22 connected to the output shaft so that power can be transmitted. Further, the CPU 60 drives the sub motor 73 via the motor driver 56, and moves between the retraction position and the paper feeding position by interlocking the hopper 15 and the retard roller 24 that are connected to the output shaft so as to be able to transmit power. Let

  Further, the CPU 60 drives the transport motor 74 via the motor driver 57, and rotates the transport drive roller 31a and the paper discharge drive roller 32a connected to the output shaft via a train wheel (not shown). Carry P (paper feed). The CPU 60 is connected to an encoder 75 (for example, a rotary encoder) that detects rotation of the output shaft of the transport motor 74. The encoder 75 outputs a pulse signal having a pulse number proportional to the rotation amount of the transport motor 74 to the CPU 60. In the present embodiment, the conveyance motor 74, the conveyance roller pair 31, the paper discharge roller pair 32, and the like constitute conveyance means.

  Further, the paper detection sensor 33 and the imaging unit 40 are electrically connected to the CPU 60. The paper detection sensor 33 outputs to the CPU 60 an on / off signal that is turned off when paper is detected and is turned on when paper is detected. Further, the image data (frame) in which the image pickup element 45 in the image pickup unit 40 picks up the texture of the back surface of the paper P at regular time intervals (unit drive time) is input from the image pickup unit 40 to the CPU 60.

  The CPU 60 also includes a paper position counter (hereinafter referred to as “position counter 66”) and a PF counter 67. The position counter 66 is input from the encoder 75 with a position at a predetermined distance from the detection position at which the paper detection sensor 33 detects the leading edge of the paper P (no paper → paper present) to the downstream side in the transport direction as an origin (for example, the most upstream nozzle position). The conveyance position of the paper P is counted by counting the number of pulse edges of the pulse signal to be generated.

  The PF counter 67 is a relative position of the paper P in one transport operation section from the transport start position (previous recording position) to the transport end position (next recording position) in the course of one transport operation of the paper P. Count. Specifically, the PF counter 67 is set with a value corresponding to the target transport amount from the current position (transport start position) to the transport end position (target position) of the paper P prior to the start of transport. The PF counter 67 decrements (subtracts) the count value by “1” every time the pulse edge of the pulse signal is input from the encoder 75. For this reason, the PF counter 67 counts the remaining conveyance amount up to the target position. The CPU 60 sequentially grasps the transport position of the paper P in the course of one transport operation from the count value of the PF counter 67. Then, the CPU 60 refers to the speed control data VD stored in the nonvolatile memory 64, obtains a speed command value corresponding to the transport position at that time, and commands the speed command value to the motor driver 57. The conveyance motor 74 is speed controlled along a preset speed profile.

  In the movement amount calculation process performed by the CPU 60 executing the program shown in FIG. 8, the unit of the paper P is obtained by comparing the two images before and after the imaging unit 40 captures every predetermined time (unit driving time) in time series. The movement amount Δy for each driving time is sequentially calculated. Then, by accumulating the movement amount Δy per unit driving time over the entire conveyance operation section from the conveyance start position to the conveyance stop position of the sheet P, the sheet P is actually conveyed in one conveyance operation. The actual transport amount Yr (= Δy1 + Δy2 +... + Δyn) (where n is the cumulative number) is calculated.

  Next, the movement amount calculation process will be described in detail. 4A and 4B show two images (frames) before and after being captured by the imaging unit 40 and compared in time series. In each of the images F1 and F2, the texture of the back surface of the paper P is captured. First, in the Nth image F1 shown in FIG. 4A (where N is a natural number), a template TP in a rectangular area, for example, is positioned at a predetermined position (template determination position) upstream in the transport direction Y in the image. To decide. The template determination position is set to a position where the rectangular area determined as the template TP in the image F1 can be accommodated in the next frame F2 after the unit driving time has elapsed. The texture of the template TP is a unique paper pattern that does not appear elsewhere on the back side of the paper P.

  In the next (N + 1) th image F2, the overlapping rectangular area indicated by the broken line while moving the template TP determined in the previous Nth image on the image F2 in FIG. A template matching process is performed in which the degree of similarity with a rectangular area for each small pitch) is calculated in order, and the position of the matching area MA where the degree of similarity is maximized is found. As a result of the template matching process, when a matching area MA matching the template TP is found as shown in FIG. 4B, the position where the template TP is determined in the image F2 (for example, the center coordinates of the template TP) and the matching The distance in the transport direction Y from the position of the area MA (for example, the center coordinates of the matching area MA) is calculated. The calculated distance is set as a calculated movement amount Δy per unit driving time.

  By the way, if dirt or ink adheres to the translucent glass 41 of the imaging unit 40 and becomes dirty, for example, if a rectangular region including dirt in the Nth image is determined as the template TP, template matching processing is performed. When this is done, the dirt position is selected as the matching area MA. In this case, a calculation error of the calculated movement amount Δy occurs. In the present embodiment, when this type of calculation error occurs, the calculation movement amount Δy in which there was a calculation error is handled based on the calculation movement amount Δy in which no other unit driving time (unit interval) has been calculated. The calculated movement amount Δy of the unit section is supplemented by interpolation calculation. Then, the actual transport amount Yr is calculated by integrating all the calculated travel amounts Δy over the entire transport operation section including the interpolated calculated travel amount Δy.

  FIG. 7 is a graph showing the reference data RD used in the interpolation calculation. In this graph, the horizontal axis represents time, and the vertical axis represents transport speed, and shows a speed profile in one transport operation section from the transport start position to the transport stop position. For convenience of explanation, this graph shows the number of unit sections (intervals between broken lines in the figure) obtained by dividing the transport operation section for every fixed unit driving time as a schematic diagram that is considerably smaller than the actual number. .

  The speed profile of the conveyance control shown in FIG. 7 is shown with a trapezoidal waveform for convenience of explanation. The acceleration area AA in which the conveyance speed is accelerated from the conveyance start position (time t1) to the acceleration end position Pa (time t5), and the constant conveyance speed from the acceleration end position Pa (time t5) to the deceleration start position Pd (time t11). 3 speed areas including a constant speed area CA held by the vehicle and a deceleration area DA where the conveyance speed is decelerated from the deceleration start position Pd (time t11) to the conveyance stop position. Each speed profile in the acceleration area AA and the deceleration area DA actually draws a predetermined acceleration curve and deceleration curve, respectively.

  The reference data RD is data in which a theoretical movement amount for each unit driving time in the transport operation section is set. In the example of FIG. 7, theoretical movement amounts “A”, “B”, “C”... “N” for each unit driving time are set. Specifically, the theoretical movement amounts “A”, “B”, “C”, and “D” for each unit driving time are set in the acceleration area AA, and the theoretical movement amounts for each unit driving time are set in the constant speed area CA. Movement amounts “E”, “F”, “G”, “H”, “I”, and “J” are set. Further, theoretical movement amounts “K”, “L”, “M”, and “N” for each unit driving time are set in the deceleration area DA. In FIG. 7, the calculated movement amount Δy for each unit driving time in the transport operation section is shown as “a”, “b”, “c”,. In this embodiment, for example, it is determined whether or not the calculated movement amount Δy is within a preset normal range. In the case of a calculation error in which the calculated movement amount Δy is determined to be outside the normal range, the calculated movement determined to be within the normal range in another unit section belonging to the same speed region as the unit section of the calculation error. Based on the amount Δy and the theoretical movement amount, the calculated movement amount Δy of the unit section in which the calculation error has occurred is calculated by interpolation.

  The speed control data VD for transport control is set in the same manner as the graph shown in FIG. 7 (however, the horizontal axis is the transport position), and if the constant speed in the constant speed region is the same, deceleration starts. The deceleration distance required when decelerating along the deceleration profile from the position Pd to the conveyance stop position is always constant. Therefore, by shifting the deceleration start position Pd in the transport direction Y and resetting it, it is possible to shift the transport stop position in the transport direction Y and adjust the actual transport amount. In this embodiment, the deceleration start position Pd is updated (reset) in the middle of the transport operation, thereby controlling the actual transport amount Yr to an appropriate value.

  In the present embodiment, the position two units before the deceleration start position Pd (time t9) is set as the calculation start position Pc of the deceleration start position for executing the calculation for resetting the deceleration start position Pd. Here, the calculation start position of the deceleration start position is calculated by linear approximation using all the calculated movement amounts Δy from the transfer start position so far to reduce errors caused by the positional deviation due to the previous slip or the like. Thus, the calculation for obtaining the deceleration start position Pd is set to a position at a timing in time until the sheet P reaches the deceleration start position Pd and the deceleration control is started. Then, at the calculation execution position Pc, the deceleration start position Pd that can make the actual conveyance amount coincide with the target conveyance amount is calculated using the plurality of calculated movement amounts Δy accumulated up to this point from the current conveyance start position. The deceleration start position Pd is set (updated) instead of the initial deceleration start position Pd determined from the speed control data VD and the target transport amount. When the transport position of the paper P reaches the set deceleration start position Pd, the constant speed control is shifted to the deceleration control according to a predetermined deceleration profile.

  When the CPU 60 executes the program PR including the routines shown in FIGS. 8 and 9, the functional configuration shown in FIG. 6 necessary for carrying the paper P is controlled in the computer 51. The template determining unit 81 shown in FIG. 6 cuts out a rectangular region at a predetermined position upstream in the transport direction in an image (frame) in which the texture of the back surface of the paper P input from the image sensor 45 is captured. To decide. The template TP is stored in a predetermined storage area of the RAM 63, for example.

The template matching unit 82 performs a template matching process that finds a matching area MA by comparing the template TP while moving the template TP in the next image.
The movement amount calculation unit 83 calculates the distance in the transport direction Y between the position (coordinates) of the template TP determined in the previous image and the position (coordinates) of the matching area MA in the next image, and the distance is unit driven. The calculated movement amount per time Δy. In the present embodiment, the template determination unit 81, the template matching unit 82, and the movement amount calculation unit 83 constitute an example of a movement amount calculation unit.

  The error determination unit 84 as an example of a determination unit determines whether or not the calculated movement amount Δy is within a preset normal range. If the calculated movement amount Δy is within the normal range, it is determined that the calculated movement amount Δy is normally calculated, and the normal calculated movement amount Δy is calculated as the actual conveyance amount and the calculation of the deceleration start position Pd. It is set as the movement amount control value used for. On the other hand, if the calculated movement amount Δy is not within the normal range (that is, outside the normal range), it is determined that the movement amount Δy is a calculation error. Here, the normal range is set to a range of a predetermined fluctuation amount (for example, a predetermined value within a range of ± 5 to 15%) with respect to the theoretical movement amount, for example. For example, the lower limit of the normal range is set to a value that is smaller by a margin than the amount of movement that the sheet can be conveyed during the unit drive time when the maximum slip expected between the sheet P and the conveyance roller pair 31 or the like occurs. Is set. The normal range is set so that only the amount of movement that cannot be clearly taken out due to dirt or the like of the translucent glass 41 is outside the normal range. In addition, one normal range may be set for each speed region, or individual data may be set for each speed region. The normal range data is stored in the nonvolatile memory 64 in advance.

  The determination unit 85 includes a miscounter (not shown) that counts the number of consecutive calculation errors. When the error determination unit 84 determines that a calculation error has occurred, the calculation error continues for the Pth time (however, P is 2 or more). Or a natural number). In this embodiment, for example, P = 2. The determination unit 85 determines whether or not the previous calculated movement amount Δy of the unit section is a calculation error when the error determination unit 84 determines that the calculated movement amount Δy of the current unit section is not a calculation error. A determination process is also performed.

  The interpolation unit 86 performs a process of interpolating the calculated movement amount Δy of the unit drive time (unit section) determined to be a calculation error by interpolation calculation. The interpolation unit 86 includes a speed region determination unit 86A, an acceleration interpolation unit 86B, a constant speed interpolation unit 86C, and a deceleration interpolation unit 86D. The speed region determination unit 86A determines which of the three speed regions, the acceleration region, the constant speed region, and the deceleration region, the unit section in which the calculation error has occurred belongs. Then, the acceleration interpolation unit 86B is activated if belonging to the acceleration region, the constant speed interpolation unit 86C is activated if belonging to the constant velocity region, and the deceleration interpolation unit 86D is activated if belonging to the deceleration region.

The acceleration interpolation unit 86B includes two calculation movement amounts Δy that are determined to be within the normal range in the unit sections before and after the miscalculated unit section, the miscalculated unit section obtained from the reference data RD, and the preceding and following unit sections. Based on these three theoretical movement amounts (theoretical acceleration profile), the calculated movement amount Δy (movement amount control value) of the unit section in which the calculation is missed is calculated. For example, when the calculated movement amount Δy = b in the acceleration area AA in FIG. 7 is a calculation error, the calculated movement amount b is calculated based on the following calculation formula.
b = {(B / A) × a + (B / C) × c} / 2 (1)
The constant speed interpolation unit 86C calculates the average value of the two calculated movement amounts Δy using the two calculated movement amounts Δy before and after the unit interval before and after the unit interval in which the calculation error is determined to be within the normal range. The average value is set as the calculated movement amount Δy (movement amount control value) of the unit section in which the calculation error has occurred. For example, when the calculated movement amount Δy = g is a calculation error in the constant speed region CA in FIG. 7, the calculated movement amount g is calculated based on the following calculation formula.
g = (f + h) / 2 (2)
The deceleration interpolation unit 86D has two movement amounts Δy before and after determined to be within the normal range in the unit sections before and after the miscalculated unit section, the miscalculated unit section obtained from the reference data RD, and the preceding and following unit sections. Based on these three theoretical movement amounts (theoretical deceleration profile), the calculated movement amount Δy of the unit section in which the calculation is missed is calculated. For example, when the calculated movement amount Δy = m is a calculation error in the deceleration area DA in FIG. 7, the calculated movement amount m is calculated based on the following calculation formula.
m = {(M / L) × l + (M / N) × n} / 2 (3)
By the way, when the unit section that has been miscalculated is the first unit section or the last unit section of each speed region, the normal calculated movement amount Δy is one of the preceding and following unit sections belonging to the same speed region as the unit region that has been miscalculated. Only exists. In this case, based on the normal calculated movement amount Δy of one of the unit sections before and after the unit area in which the calculation is missed that belongs to the same speed region as the unit area in which the calculation is missed, and the theoretical movement amount of the corresponding unit section, Calculate the calculated movement amount Δy of the unit section in which the calculation is missed.

  For example, when the calculated movement amount Δy = a of the first unit section in the acceleration area AA shown in FIG. 7 is a calculation error, the acceleration interpolation unit 86B sets the calculated movement amount a by a = (A / B) × b. calculate. When the calculated movement amount Δy = e of the first unit section in the constant speed area CA shown in FIG. 7 is a calculation error, the constant speed interpolation unit 86C calculates the calculated movement amount e by e = f. Further, when the calculated movement amount Δy = k of the first unit section in the deceleration area DA shown in FIG. 7 is a calculation error, the deceleration interpolation unit 86D calculates the calculated movement amount k by k = (K / L) × l. To do. Also, when the unit section in which the calculation is missed is the last unit section of each speed region, the calculated movement amount Δy in each speed region is calculated by the same method. In this example, the theoretical acceleration profile and deceleration profile correspond to an example of an acceleration / deceleration profile.

  The accumulating unit 87 uses the movement amount Δy determined by the error determination unit 84 as having no error and the movement amount Δy interpolated by the interpolation unit 86 after the error determination unit 84 has determined that there is a error as the movement used for controlling the conveyance amount. A setting unit 87A set as a quantity control value is provided. That is, the setting unit 87A accumulates data (movement amount control value) of the movement amount Δy of each unit section from the beginning of the current transport operation to the present (current). Further, the integrating unit 87 performs an integrating process of sequentially integrating the movement amount Δy set in the setting unit 87A. In the present embodiment, the interpolation unit 86 and the integration unit 87 constitute an example of a setting unit.

  When the sheet P reaches the calculation execution position Pc (see FIG. 7), the first calculation unit 88 uses the respective movement amounts Δy from the conveyance start position to the calculation execution position Pc to perform linear approximation calculation that minimizes the error. To calculate a deceleration start position Pd at which the paper P can be stopped at a target stop position where the actual transport amount can be matched with the target transport amount. Then, the first calculation unit 88 sets the obtained deceleration start position Pd data in the deceleration start position setting unit 89.

  The second calculation unit 90 compares the current actual transport amount Yr accumulated by the accumulating unit 87 at the end of the transport operation with the current target transport amount Yt, so that the difference between the two is reduced next time. The target carry amount Yt is corrected for feedback.

  The update unit 91 reads the next target carry amount from the predetermined storage area of the RAM 63, performs a correction operation for adding a correction using a parameter based on feedback correction to the next target carry amount, and sets the next target carry amount Yt. Update. Then, the update unit 91 sets the updated next target transport amount Yt in the target transport amount setting unit 92.

  The transport controller 93 controls the transport motor 74 to control the transport speed and transport amount for each transport operation of the paper P, and transports the paper P to the next recording position with high positional accuracy. Specifically, first, the transport control unit 93 sets the target transport amount Yt set in the target transport amount setting unit 92 in the PF counter 67 and reads the speed control data VD. Then, when the conveyance operation is started, the conveyance control unit 93 decrements the count value of the PF counter 67 every time the pulse edge of the pulse signal from the encoder 75 is input. The transport controller 93 grasps the current transport position of the sheet P starting from the transport start position based on the count value of the PF counter 67, that is, the remaining transport amount up to the stop position. The transport controller 93 sequentially outputs the speed command value obtained by referring to the speed control data VD to the motor driver 57 according to the transport position of the paper P at that time, and controls the speed of the transport motor 74. As a result, the paper P is transported at a transport speed according to the speed profile shown in the graph of FIG.

  Then, when the count value of the PF counter 67 reaches a value corresponding to the calculation execution position Pc, the conveyance control unit 93 instructs the first calculation unit 88 to execute the calculation of the deceleration start position Pd. Upon receiving the instruction, the first calculation unit 88 calculates an appropriate deceleration start position Pd by linear approximation that reduces the error based on each calculated movement amount Δy from the conveyance start position to the calculation execution position Pc. The calculated deceleration start position Pd is set in the deceleration start position setting unit 89. Thereafter, when the count value of the PF counter 67 reaches the updated deceleration start position Pd set in the deceleration start position setting unit 89, the conveyance control unit 93 starts the deceleration control of the conveyance motor 74. For this reason, the paper P stops at the target stop position that has been transported by the required target transport amount from the transport start position. In the present embodiment, the first calculation unit 88, the deceleration start position setting unit 89, the second calculation unit 90, the update unit 91, the target transfer amount setting unit 92, and the transfer control unit 93 constitute an example of a control unit. The

Next, the operation of the printer 11 of this embodiment will be described.
When the print data is received from the host device, the computer 51 in the control device 50 interprets the command in the print data, and feeds, conveys, and records the paper P according to the interpreted command. That is, the computer 51 first drives the feeding motor 72 and the transport motor 74 to feed the paper P to the printing start position (indexing position). Thereafter, a printing operation for ejecting ink droplets from the recording head 19 during the scanning of the carriage 18 in the main scanning direction X by driving the carriage motor 71, and a transporting operation for the paper P by driving the transporting motor 74. Alternately. Thereby, the printing of the image based on the print data on the surface of the paper P is advanced. During the transport operation, the CPU 60 executes a movement amount calculation processing routine (FIG. 8) and a transport control routine (FIG. 9), so that the transport operation of the paper P is feedback-controlled.

  Hereinafter, the movement amount calculation processing routine and the conveyance control routine performed by the computer 51 will be described. When performing the transport operation, at least in the transport operation section from the transport start time to the transport stop time, the imaging unit 40 images the texture of the back surface of the paper P through the translucent glass 41 at regular time (unit drive time) intervals. The captured image data (frame) is input to the computer 51 at regular time intervals.

  First, in step S1, it is determined whether image data has been acquired. If no image data has been acquired, the process waits. If image data has been acquired, the process proceeds to step S2. In the present embodiment, the process of step S1 corresponds to a detection step.

  In step S2, a template TP is determined in the acquired image (frame). That is, as shown in FIG. 4A, the template determination unit 81 determines the template TP at a predetermined position (template determination position) on the upstream side in the transport direction Y in the image F1. Then, the template determination unit 81 stores the template TP cut out from the frame F1 in a predetermined storage area of the RAM 63.

  In the next step S3, template matching processing is performed. That is, as shown in FIG. 4B, the template matching unit 82 calculates the similarity with the overlapping rectangular area while moving the template TP in the image F2, and the position of the matching area MA where the similarity is maximized. Find out. When the matching area MA is found, the process proceeds to step S4.

  In step S4, the movement amount Δy is calculated. That is, the movement amount calculation unit 83 calculates the distance in the transport direction Y between the center coordinates of the template determination position and the center coordinates of the matching area MA, and calculates this as the calculated movement amount Δy per unit driving time (unit section). To do. The movement amount calculation unit 83 stores the calculated movement amount Δy in a predetermined storage area of the RAM 63. In the present embodiment, the processing in steps S2 to S4 corresponds to a movement amount calculating step.

  In the next step S5, it is determined whether or not the calculated movement amount Δy is a calculation error. That is, the error determination unit 84 determines whether or not the calculated movement amount Δy is within a preset normal range. If the calculated movement amount Δy is within the normal range and there is no calculation error (No in S5), the calculation error flag is set to “0” indicating that there was no calculation error, and the calculated movement amount Δy within the normal range is set. After setting in the setting unit 87A, the process proceeds to step S7. On the other hand, when the calculated movement amount Δy is out of the normal range and is determined to be a calculation error (positive determination in S5), the error determination unit 84 sets “1” to the effect that there was a calculation error in the calculation error flag, “1” is added to a miss counter (not shown) that counts the number of consecutive calculation mistakes. Prior to the start of the transport operation, the error determination unit 84 resets the error counter to set the count value to “0”, and also resets the count value to “0” when there is no calculation error. . For this reason, the number of consecutive calculation errors is counted in the miss counter. In the present embodiment, the process of step S5 corresponds to a determination step.

  In step S6, it is determined whether the calculation mistake is the continuous Pth. That is, the determination unit 85 determines whether or not the calculation error is the continuous P-th time based on the count value of the miss counter. If it is not the P-th time, the process returns to step S1. In this embodiment, since P = 2, the process returns to step S1 if the calculation error is the first time, but if the calculation error is the second time, a calculation error occurs. This is because if the calculation error occurs twice consecutively, the medium may be a resin film with substantially no texture, or dirt such as ink or dirt may adhere to the surface of the translucent glass 41. This is because it is presumed to be the cause and it can be determined that the calculated movement amount Δy cannot be detected.

  On the other hand, if it is not a calculation error, it is determined in step S7 whether or not there was a previous calculation error. That is, the determination unit 85 determines that there is a previous calculation error if the value of the calculation error flag is “1”, and that there is no previous calculation error if the value is “0”. If there was a previous calculation error, the process proceeds to step S8. If there was no previous calculation error, the process proceeds to step S12.

  In step S12, it is determined whether or not the calculation is completed. That is, it is determined whether or not calculation of the calculated movement amount Δy for all unit sections in the transport operation section has been completed. If the calculation is completed, the routine is terminated. If the calculation is not completed, the process returns to step S1.

  On the other hand, if it is determined in step S7 that there was a previous calculation error, in step S8, it is determined to which speed region the unit section in which the previous calculation error has belonged. Here, the conveyance control unit 93 outputs a speed command value corresponding to each conveyance position y indicated by the count value of the PF counter 67 to the motor driver 57, thereby conveying the sheet P in the conveyance operation section (that is, conveyance). If the transport position y is known, the speed region to which the transport position y belongs can be specified by referring to the speed control data VD. Based on the count value of the PF counter 67, the speed area determination unit 86A identifies the transport position y where the previous mistake occurred, and refers to the speed area to which the identified transport position y belongs, for example, the speed control data VD. get. Then, the speed region determination unit 86A proceeds to step S9 when it is determined that the unit section having the previous mistake belongs to the acceleration region, proceeds to step S10 when it is determined to belong to the constant speed region, and further enters the deceleration region. If it is determined to belong, the process proceeds to step S11.

  In step S9, the movement amount Δy of the section in which the calculation is missed is calculated using the acceleration curve theory. That is, the acceleration interpolation unit 86B is within the normal range belonging to the same acceleration region as the unit interval in which the theoretical movement amount per unit interval in the acceleration curve (theoretical acceleration profile) acquired from the reference data RD and the unit interval in which the calculation is missed By performing an interpolation calculation using the calculated movement amount Δy of at least one unit section determined to be, the calculated movement amount Δy of the unit section in which the calculation is missed is interpolated. In particular, the acceleration interpolation unit 86B includes the calculated movement amount Δy of two unit sections that are determined to be within the normal range before and after the unit section in which the calculation is missed, Interpolation calculation is performed using the respective theoretical movement amounts of the three unit intervals including the unit interval, and the calculated movement amount Δy of the unit interval having the calculation error is interpolated. For example, when the calculated movement amount Δy = b is a calculation error in the acceleration area AA in FIG. 7, the calculation movement amount b is calculated by performing the interpolation calculation based on the equation (1). If there is a calculation error in the first or last unit section of the acceleration region, the unit is determined to be a unit section belonging to the acceleration region next to the unit section in which the calculation error occurred and within the normal range. Interpolation calculation is performed based on the calculated movement amount Δy of the section and the corresponding two theoretical movement amounts to calculate the calculated movement amount Δy of the unit section in which the calculation error has occurred.

  In step S10, the movement amount of the section in which the calculation error is calculated by averaging the front and rear values is calculated. That is, the constant speed interpolation unit 86C averages the calculated movement amount Δy of at least one unit section determined to be within the normal range belonging to the same constant speed area as the unit section in which the calculation is missed, The calculated movement amount Δy is calculated. In particular, the constant speed interpolation unit 86C averages the calculated movement amounts Δy of the two unit sections that are determined to be within the normal range before and after (both adjacent to) the unit section in which the calculation is incorrect, The calculated movement amount Δy is calculated. For example, when the calculated movement amount Δy = g is a calculation error in the constant speed area CA in FIG. 7, the movement amount g is calculated based on the equation (2). If there is a calculation error in the first or last unit section of the constant speed region, one calculated movement amount Δy determined to be within the normal range among the unit sections before and after the unit section in which the calculation error occurred. Is the calculated movement amount Δy of the unit section where the calculation error occurred.

  In step S11, the movement amount of the section in which the calculation is missed is calculated using the theory of the deceleration curve. That is, the deceleration interpolation unit 86D is within the normal range that belongs to the same deceleration region as the unit interval in which the theoretical movement amount per unit interval in the deceleration curve (theoretical deceleration profile) acquired from the reference data RD is miscalculated. By performing an interpolation calculation using the calculated movement amount Δy of at least one unit section determined to be, the calculated movement amount Δy of the unit section in which the calculation is missed is interpolated. In particular, the deceleration interpolation unit 86D includes the amount of movement Δy between two unit sections that are determined to be within the normal range before and after the miscalculated unit section, and the miscalculated unit section and the units before and after it. Interpolation calculation is performed using the theoretical movement amounts of the three unit sections including the section, and the movement amount Δy of the unit section having the calculation error is interpolated. For example, when the calculated movement amount Δy = m is a calculation error in the deceleration area DA in FIG. 7, an interpolation calculation based on the equation (3) is performed to calculate the calculated movement amount m. If there is a calculation error in the first or last unit section of the deceleration area, the unit is determined to be a unit section belonging to the deceleration area and within the normal range next to the unit section where the calculation error occurred. Interpolation calculation is performed based on the calculated movement amount Δy of the section and the corresponding two theoretical movement amounts to calculate the calculated movement amount Δy of the unit section in which the calculation error has occurred. In the present embodiment, the setting process for the setting unit 87A for the calculated movement amount Δy and the processes of S7 to S11 in step S5 correspond to the setting steps.

  For this reason, even if there is a calculation mistake, all the calculated movement amounts from the transfer start position (time t1) to the calculation execution position Pc (for example, time t9) before reaching the deceleration start position Pd during the transfer operation. Δy is obtained. Therefore, by using all the calculated movement amounts Δy from the conveyance start position to the calculation execution position Pc, the deceleration start position Pd at which the paper P can be stopped at the target stop position is calculated by linear approximation that reduces the error. You can get it. When the calculation is completed, the calculated movement amount Δy of all the unit sections over the entire transport operation section is acquired. For this reason, the actual transport amount Yr can be acquired by integrating all the calculated movement amounts Δy in the transport operation section.

  Next, an appropriate deceleration start position Pd is derived and the stop position is corrected to set the next target transport amount based on the process of bringing the actual transport amount closer to the target transport amount and the actual transport amount and the target transport amount. The feedback control will be described with reference to FIG. In the present embodiment, this transport control routine corresponds to a control step.

  In step S21, a target carry amount is set. That is, the conveyance control unit 93 reads the target conveyance amount Yt from the target conveyance amount setting unit 92 and sets the value in the PF counter 67. The transport controller 93 refers to the speed control data VD based on the current transport position indicated by the count value of the PF counter 67 that is decremented by “1” each time the pulse edge of the pulse signal is input from the encoder 75. By outputting the speed command value acquired in this way to the motor driver 57, the transport motor 74 is speed controlled according to a predetermined speed profile. The speed control of the transport motor 74 is performed as follows.

  First, in step S22, acceleration control is performed. In other words, while the transport position indicated by the count value of the PF counter 67 is in the acceleration region, the transport control unit 93 outputs a speed command value corresponding to the transport position at that time in the acceleration region to the motor driver 57 to perform transport. By accelerating the rotation speed of the motor 74, the conveyance speed of the paper P is accelerated along the acceleration profile.

  In the next step S23, it is determined whether or not the acceleration end position Pa has been reached. That is, the conveyance control unit 93 determines whether or not the count value of the PF counter 67 has reached the acceleration end position Pa. If the acceleration end position Pa has not been reached, the acceleration control in step S22 is continued. If the acceleration end position Pa has been reached, the process proceeds to step S24.

  In step S24, constant speed control is performed. That is, the conveyance control unit 93 outputs a speed command value of a constant speed (target speed) to the motor driver 57 while the conveyance position indicated by the count value of the PF counter 67 is in the constant speed region, By driving at a constant target speed, the paper P is held at a constant transport speed (target speed).

  In step S25, it is determined whether or not the calculation start position of the deceleration start position has been reached. If the calculation execution position has not been reached, the constant speed control in step S24 is continued. If the calculation execution position has been reached, the process proceeds to step S26.

  In step S26, a deceleration start position is calculated based on a plurality (all) of movement amounts from the conveyance start time. That is, the first calculation unit 88 performs a linear approximation calculation that reduces an error in misalignment caused by slip or the like based on all the calculated movement amounts Δy from the conveyance start time, and calculates the actual conveyance amount as the target conveyance amount. The deceleration start position Pd that can be matched with the above is obtained. Then, the first calculation unit 88 sets the obtained deceleration start position Pd data in the deceleration start position setting unit 89, and resets (updates) the deceleration start position Pd.

  In the next step S27, it is determined whether or not the deceleration start position has been reached. That is, the conveyance control unit 93 determines whether or not the conveyance position y of the paper P based on the count value of the PF counter 67 has reached the deceleration start position Pd set in the deceleration start position setting unit 89. If it has not reached the deceleration start position Pd, it waits until it reaches the deceleration start position Pd while continuing constant speed control, and if it reaches the deceleration start position Pd, it proceeds to step S28.

  In step S28, deceleration control is performed. In other words, while the transport position y indicated by the count value of the PF counter 67 is in the deceleration area, the transport control unit 93 outputs a speed command value corresponding to the current transport position y in the deceleration area to the motor driver 57. Then, the conveyance speed of the paper P is reduced by reducing the rotation speed of the conveyance motor 74.

  In the next step S29, it is determined whether or not the operation has been stopped. That is, when the pulse edge from the encoder 75 is not input for a predetermined time, the conveyance control unit 93 determines that the conveyance motor 74 is stopped and conveyance of the paper P is stopped. If the transport motor 74 is not stopped, the deceleration control in step S28 is continued. If it is determined that the transport motor 74 has stopped, the process proceeds to step S30.

  In step S30, all the movement amounts Δy are integrated to obtain the actual conveyance amount. That is, the accumulating unit 87 accumulates all the calculated movement amounts Δy accumulated in the setting unit 87A from the conveyance start time to the conveyance stop time, or adds the actual conveyance amount that has been accumulated until then to the last just before the stop. Is added to obtain the actual transport amount Yr of the current transport operation section.

  In the next step S31, the next target transport amount is feedback-corrected based on the actual transport amount and the target transport amount. That is, the second calculation unit 90 obtains the next target transport amount Yt by performing feedback correction that reduces the difference between the actual transport amount Yr and the target transport amount Yt.

  In this way, the actual transport amount Yr is measured for each transport operation, feedback correction is made to reduce the difference between the current target transport amount Yt and the actual transport amount Yr, and the next target transport amount Yt is set. Thus, since the carry motor 74 is feedback-controlled based on the actual carry amount Yr and the target carry amount Yt, the paper P is stopped at the next target stop position (recording position) with high positional accuracy. In this embodiment, when the movement amount Δy is obtained by accumulating the movement amount Δy for each fixed time, and there is a calculation error of the movement amount Δy, the normal range before and after the unit interval in which the calculation error has occurred. Using at least one calculated movement amount Δy of the two unit sections determined to be inside, calculation is performed to interpolate the movement amount Δy that has been miscalculated. For this reason, information on the position of the paper P based on an image (frame) captured by the imaging unit 40 at a certain time interval and input to the computer 51 (that is, another normal calculated movement amount Δy based on this information) is reflected. As the value, the movement amount Δy of the unit section in which the calculation is missed can be set. Therefore, for example, as in Patent Document 1, the accuracy of the calculated movement amount Δy set in the unit section in which the calculation is incorrect is increased as compared with a configuration in which a predetermined reference movement amount (reference conveyance amount) is replaced. Therefore, the accuracy of the measured actual transport amount Yr can be increased. Therefore, it is possible to perform feedback control more appropriately to increase the accuracy of the stop position of the paper P to the next recording position, thereby improving the print quality on the paper P.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) Interpolate the calculated movement amount Δy of the unit interval in which the calculation is missed using the normal calculated movement amount Δy of the other unit interval. For this reason, a value reflecting the position during conveyance of the paper P based on the image (information) taken at a fixed time interval by the imaging unit 40 can be set as the calculated movement amount Δy of the unit section in which the calculation is missed. Accordingly, since the calculated movement amount Δy with relatively high accuracy can be set in the unit section where the calculation error has occurred, the actual conveyance amount Yr with relatively high accuracy can be acquired by integrating the calculated movement amounts Δy.

  (2) Interpolation calculation is performed using the calculated movement amount Δy determined to be within the normal range of the unit section belonging to the same speed region as the unit section in which the calculation is missed. Therefore, a comparatively accurate calculation movement amount Δy can be set in the unit section in which the calculation is missed.

  (3) Since the interpolation value calculation of the acceleration area AA and the deceleration area DA is weighted using the theoretical movement amount, the interpolation value can be calculated with high accuracy, and the calculated movement amount Δy of the unit interval in which the calculation is missed can be acquired. For example, in the technique of Patent Document 1, since a predetermined reference movement amount (reference conveyance amount) is set when a calculation error occurs in the acceleration / deceleration region, the detection result of the paper position signal detection unit is not reflected and the actual conveyance amount is not reflected. The accuracy of is reduced. For this reason, the accuracy of the feedback correction using the actual transport amount is lowered, and consequently the accuracy of the transport control is lowered. On the other hand, according to the present embodiment, by using the calculated movement amount Δy of the unit section determined to be within the normal range, the imaging result of the imaging unit 40 is calculated as the calculated movement amount Δy of the unit section that has been miscalculated. Appropriate value that reflects can be set. Accordingly, the accuracy of the actual transport amount Yr is increased by the increase in the accuracy of the calculated movement amount Δy, so that the accuracy of feedback control of the transport operation can be increased.

  (4) Further, using the calculated movement amount Δy determined to be within the normal range in the preceding and following unit sections belonging to the same speed region as the unit area where the calculation error was made, the calculation movement amount Δy of the unit area where the calculation was incorrect is calculated. . Therefore, the calculation movement amount Δy with higher accuracy can be set in the unit section in which the calculation is missed.

  (5) When the unit section that has been miscalculated belongs to the constant speed region, the average of the calculated movement amounts Δy of the two front and rear unit sections that are determined to be within the normal range of the unit section that has not been miscalculated in the constant speed region The value is set as the calculated movement amount of the unit section where the calculation error occurred. Therefore, a comparatively accurate calculation movement amount Δy can be set in the unit section in which the calculation is missed.

  (6) If the unit section that has been miscalculated belongs to the acceleration area AA, the calculation movement amount Δy of the two unit sections before and after the calculation area in the acceleration area AA, the unit section that has been miscalculated, and the preceding and following unit sections Weighting is performed on the basis of the ratio of the theoretical movement amounts of the three included unit sections, and the calculated movement amount Δy of the unit section in which the calculation is missed is obtained. Therefore, it is possible to set the calculated movement amount Δy with relatively high accuracy in the unit section in which the calculation is missed in the acceleration area AA.

  (7) When the unit section that has been miscalculated belongs to the deceleration area DA, the calculated movement amount Δy of the two unit sections before and after the calculation area in the deceleration area DA, the unit section that has been miscalculated, and the preceding and following unit sections Is calculated based on the ratio of the theoretical movement amounts of the three unit intervals including the calculated movement amount Δy of the unit interval in which the calculation is missed. Therefore, it is possible to set the calculated movement amount Δy with relatively high accuracy in the unit section in which the calculation is mistaken in the deceleration area DA.

  (8) By performing feedback correction based on the actual transport amount Yr and the target transport amount Yt and determining the next target transport amount Yt, feedback control of the transport operation is performed. Therefore, the paper P can be stopped at an appropriate recording position, and as a result, the print quality printed on the paper P can be improved.

  (9) When the calculation execution position Pc in the middle of the constant speed area CA is reached, the calculation is performed by linear approximation to reduce the error using each calculation movement amount Δy so far, and the actual conveyance amount matches the target conveyance amount. The possible deceleration start position Pd is reset. Therefore, even if the target transport amount is updated, even if the position of the paper P being transported is shifted for some reason such as a change in slippage, the paper P is set to the target stop position by resetting the deceleration start position Pd. Can be stopped.

In addition, the said embodiment can also be changed into the following forms.
-The P times that should be a calculation error when calculation mistakes continue are not limited to two times, and may be three or more natural numbers such as three times or four times. For example, when P = 3 and two consecutive calculation mistakes are made, two consecutive calculation mistakes Δy using two calculation intervals Δy before and after the two unit sections that are consecutively missed are used. Each calculated movement amount Δy of the unit section is calculated. For example, if the movement amounts g and h are continuously miscalculated in the constant speed region shown in FIG. 7, the average value of the calculated movement amounts Δy of the unit sections on both sides thereof as the movement amounts g and h of the miscalculated section ( f + i) / 2 is set. In the acceleration / deceleration region, the movement amount Δy may be calculated using weighting based on the ratio of the calculated movement amount Δy between the two unit sections on both sides of the two miscalculated unit sections and the theoretical movement amount.

  ・ Even if the unit section that was further miscalculated is other than the first unit section and the last unit section of each speed region, one of the preceding and following unit segments belonging to the same speed region as the miscalculated unit region is normally calculated. The amount Δy may be adopted to calculate the calculated movement amount Δy of the section in which the calculation is incorrect. For example, when the calculated movement amount Δy = b is a calculation error in the acceleration area AA shown in FIG. 7, the acceleration interpolation unit 86B calculates the calculated movement amount b by b = (B / A) × a. If the calculated movement amount Δy = g is a calculation error in the constant speed area CA shown in FIG. 7, the constant speed interpolation unit 86C calculates the calculated movement amount g by g = f. Furthermore, when the calculated movement amount Δy = m is a calculation error in the deceleration area DA shown in FIG. 7, the deceleration interpolation unit 86D calculates the calculated movement amount m by m = (M / L) × l.

  When there is a calculated movement amount Δy determined to be within the normal range in the unit sections before and after the unit section that has been miscalculated, the normal calculation movement amount Δy of another unit section is also used to calculate the The calculated movement amount Δy may be calculated. For example, the calculated movement amount Δy of the unit section in which the calculation is missed may be obtained by using three or more calculated movement amounts Δy including the normal calculation movement amount Δy one by one before and after and two previous ones.

  In the above-described embodiment, the imaging unit 40 (detection unit) may be disposed at a position above the support base 30 to capture the surface (recording surface) of the paper P. In this case, if the area before the printing by the recording head 19 on the surface of the paper P, that is, the area upstream of the uppermost nozzle of the recording head in the transport direction is imaged, it is based on the captured image (frame). The amount of movement can be detected.

  -A conveyance means is not limited to a roller conveyance system, A belt conveyance system may be sufficient. Even in the case of belt conveyance, if the calculated movement amount of media including slippage of paper and belt is calculated and there is a calculation error in the calculated movement amount, the normal calculated movement amount of the unit section belonging to the same speed area is calculated. The same effect can be obtained by setting the calculated movement amount Δy used as a transport control value that determines the deceleration start position and the actual transport amount.

  -A detection means is not limited to the imaging unit which images the texture of a medium. For example, an optical sensor that optically detects the positions of marks provided at regular intervals in the conveyance direction of the medium may be used. In this case, the mark may be a mark printed on the paper or a hole (for example, a punch hole) opened in the paper. According to this configuration, the position can be detected even on a medium having substantially no texture such as a resin film. Further, the detection means may be an ultrasonic sensor that detects the transport position of the medium using the Doppler effect. Further, the detection means may be a motion sensor that detects the transport position of the medium by irradiating the medium with a coherent light beam and using a speckle pattern generated in the reflected light.

  One of the calculation of the deceleration start position and the calculation of the actual conveyance amount Yr is adopted, the conveyance control based on the reset of the deceleration start position, and the feedback control for reducing the difference between the actual conveyance amount and the target conveyance amount, The structure which employ | adopts only any one of these may be sufficient.

  ・ Acquire an image (frame) that captures an area including marks that are marked at regular intervals in the conveyance direction of the medium at unit drive time intervals, and compare the positions of the marks in the two images before and after the image. A configuration for calculating the movement amount per driving time can also be adopted.

The medium is not limited to a short medium such as cut paper, but may be a long medium such as roll paper.
The medium is not limited to paper, and may be a resin film, metal foil, metal film, resin-metal composite film (laminate film), woven fabric, non-woven fabric, ceramic sheet, and the like. Furthermore, a three-dimensional object having a flat surface (imaged surface) extending in the transport direction on the bottom surface or the top surface may be used.

  In the above-described embodiment, the recording apparatus is embodied as an ink jet recording apparatus. However, the present invention is not limited to this, and liquids other than ink, liquids obtained by dispersing or mixing functional material particles in liquids, gels, and the like It is also possible to embody the present invention in a liquid ejecting apparatus that ejects or discharges a fluid (including such a fluid). For example, even in a liquid ejecting apparatus that ejects a liquid material that contains materials such as electrode materials and color materials (pixel materials) used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, and surface-emitting displays in a dispersed or dissolved state. Good. Further, it may be a liquid ejecting apparatus that ejects a bio-organic material used for biochip manufacture, or a liquid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample. Furthermore, a liquid ejecting apparatus that ejects a transparent resin liquid such as a thermosetting resin onto a substrate to form a micro hemispherical lens (optical lens) used for an optical communication element or the like, an acid or an alkali to etch the substrate, etc. The liquid injection apparatus which injects etching liquids, such as a fluid body injection apparatus which injects fluid bodies, such as gel (for example, physical gel), may be sufficient. The present invention can be applied to any one of these fluid ejecting apparatuses. As described above, the medium (recording medium) may be a substrate on which elements, wirings, and the like are formed by inkjet. The “liquid” ejected by the liquid ejecting apparatus includes a liquid (including an inorganic solvent, an organic solvent, a solution, a liquid resin, a liquid metal (metal melt), etc.), a liquid, a fluid, and the like.

  The medium conveying device is not limited to application to a recording device such as a printer. For example, a scanner that transports a medium for the purpose of reading an image recorded on the medium, a cutting device that is transported to cut paper, a paper processing device that is transported to process paper, a liquid material such as adhesive or water Can be employed in a coating device that transports a medium for coating the brush with a brush portion or a roller for coating, a packaging device that transports packaging paper to a packaging mechanism for packaging articles, and the like. In addition, the present invention can be widely applied to other apparatuses including a medium conveying apparatus that conveys a medium. Needless to say, a medium conveying apparatus only for conveying a medium may be used alone.

  The “information regarding the position of the medium” detected by the detecting means is not limited to the image (frame) of the medium imaged at a constant time interval. For example, the detection signal of an optical sensor that optically detects the positions of marks placed at regular intervals in the transport direction on the front or back surface of the medium, or the ultrasonic sensor in the case of detecting the position of the medium with an ultrasonic sensor It may be a detection signal. In short, the information on the position of the medium may be position information that can directly acquire the position from the information, or information that can acquire the position of the medium by performing predetermined processing such as image processing or signal processing on the information.

  DESCRIPTION OF SYMBOLS 11 ... Printer which is an example of a recording apparatus, 18 ... Carriage which comprises an example of a recording means, 19 ... Recording head which comprises an example of a recording means, 22 ... Paper feed roller, 30 ... Support stand, 31 ... Pair of conveyance rollers, 32 ... Paper discharge roller pair, 40 ... Imaging unit as an example of detection means, 43 ... Light emitting unit, 45 ... Imaging device, 50 ... Control device, 51 ... Computer, 57 ... Motor driver, 67 ... PF counter, 71 ... Carriage Motor 72, feeding motor 74, transport motor 75, encoder 81, template determining unit constituting an example of moving amount calculating means 82, template matching unit constituting an example of moving amount calculating means 83 moving Movement amount calculation unit constituting an example of the amount calculation unit, 84... Miss determination unit as an example of the determination unit, 85. 6... Interpolation section constituting an example of setting means, 86A... Speed region determination section, 86B... Acceleration interpolation section, 86C... Constant speed interpolation section, 86D. 87A ... setting section, 88 ... first calculation section constituting an example of control means, 89 ... deceleration start position setting section constituting an example of control means, 90 ... second calculation section constituting an example of control means, 91 ... An update unit constituting an example of the control means, 92... A target carry amount setting part constituting an example of the control means, 93... A conveyance control part constituting an example of the control means, P. Scanning direction, Y: sub-scanning direction (conveyance direction), Δy: calculated movement amount as an example of calculated movement amount, AA: acceleration area, CA: constant speed area, DA: deceleration area, Pc: calculation of deceleration start position Position, Pd: Deceleration start position, Yr: Actual transport amount, Y t: Target conveyance amount.

Claims (3)

Conveying means for conveying the medium;
First detecting means for detecting a driving amount of the conveying means;
Control means for controlling the transport means based on the detection result of the first detection means to transport the medium by a target transport amount;
Second detection means for detecting information relating to the position of the medium conveyed by the conveyance means;
A movement amount acquisition means for acquiring the detected movement amount of the medium for each unit driving time by comparing information on the position detected by the second detection means in order of time series; and
When transporting the medium so that the transport means corresponds to a preset acceleration / deceleration profile, the theoretical movement amount per unit drive time,
The control means adds the detected movement amount when the detected movement amount is within a normal range, and unit drive that was out of the normal range when the detected movement amount is outside the normal range. The detected movement amount that was within the normal range in at least one unit drive time before and after the time, the unit drive time that was outside the normal range, and at least one unit drive time before and after the unit drive time And adding the interpolated movement amount in the corresponding unit driving time interpolated based on the ratio of the theoretical movement amounts of a plurality of unit driving times including as a detected movement amount, thereby accumulating the detected movement amount for each unit driving time The medium transport device that acquires the actual transport amount given as, and corrects the next target transport amount based on the difference between the actual transport amount and the target transport amount . A medium conveying device according to claim 1 ;
A recording apparatus comprising: recording means for recording on a medium conveyed by the medium conveying apparatus. A first detection step of detecting a drive amount of a transport means for transporting the medium;
A control step of controlling the transport means based on the detection result in the first detection step to transport the medium by a target transport amount;
A second detection step of detecting information relating to the position of the medium conveyed by the conveying means;
A movement amount acquisition step of acquiring the detected movement amount of the medium for each unit driving time by comparing information on the position detected by the second detection step in time series order; and
In the control step, when the transport means transports the medium so that the theoretical travel distance per unit driving time corresponds to a preset acceleration / deceleration profile, the detected travel distance is within a normal range. If the detected moving amount is outside the normal range, the detected moving amount is within the normal range in at least one unit driving time before and after the unit driving time outside the normal range. And a ratio of theoretical movement amounts of a plurality of unit drive times including a unit drive time that is outside the normal range and at least one unit drive time before and after the unit drive time. obtaining an interpolation movement amount in a unit drive time corresponding to interpolate, by adding the detecting the movement amount, the actual conveyance amount given as a cumulative value of the detected movement amount of each of the unit driving time , The medium transport control method characterized by correcting the target carry amount for the next based on the difference between the actual transport amount and the target carry amount.