JP2018083678A - Detection device and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the amount of movement of a medium such as a sheet without prolonging the detection period of moving speed.SOLUTION: A detection device is characterized in that: an output result of pattern matching is output to a captured image obtained by imaging a printing medium for each period; where a moving speed of the printing medium is acquired, movement amount information obtained by detection processing with respect to each of a plurality of images is used; and where the cumulative amount of movement of the printing medium is acquired, not the movement amount information indicating that a template of the detection processing for the captured image to be processed next is not changed but the movement amount information indicating that a template of the detection processing for the captured image to be processed next is changed is used as second information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a detection device and a detection method for detecting a conveyance amount of a medium such as paper.

  In an image printing apparatus that forms an image on a medium by a recording unit while conveying a medium such as paper, the amount of movement of the print medium can be indirectly detected by detecting the rotation of a roller used for conveyance with an encoder. Has been done. However, when the print medium transported by the rollers slips or there is an error in the rollers, the detected movement amount may not match the actual movement amount of the print medium. Therefore, in order to detect the amount of paper movement with high accuracy, we propose a printer that captures the surface of the paper at a predetermined cycle, performs pattern matching processing to calculate the amount of paper movement, and provides feedback to the transport operation. (Patent Document 1).

  Further, Patent Document 2 discloses a method of obtaining an actual transport amount in which a sheet is actually transported in one transport operation by integrating the travel amounts obtained based on images picked up in each cycle. Has been.

JP 2013-231658 A JP 2013-099902 A

  In Patent Document 1, the surface layer of paper is imaged at a fixed period, and the amount of movement is obtained by a correlation detection process between a reference image (hereinafter referred to as a template) and the captured image. In the method of Patent Document 1, when the conveyance amount from the template position is small, no output is performed, and when the maximum conveyance amount is within the range not exceeding the imaging sensor length, Outputs the time required for movement. The moving speed of the paper is obtained from this moving amount and time.

  FIG. 9 is a diagram for explaining the operation of Patent Document 1, in which a reference template is created and stored from image 0 captured at a certain timing, and image 1, image 2, and image captured at subsequent timings are stored. 3 is compared. The moving direction of the print medium is from left to right in the drawing.

  Image 1 and image 2 are not output because the amount of movement from image 0 is small and there is room for the imaging region (sensor reading region). In image 3, since the pattern corresponding to the template is at the right end of the imaged area, it is determined that the movement amount is sufficient, and the movement amount is output, and the next template image (the left region in image 3) is output. Image) and save it. Using this as a template, pattern matching processing is performed on images after image 4.

  However, in the method of Patent Document 1, the period in which the movement amount is output differs depending on the conveyance speed. The reading area of the sensor is fixed, and the time required for the paper to move a predetermined distance depends on the conveyance speed. For this reason, when the conveyance speed is halved, it takes twice as much time to reach the same movement amount, so the period of output of the movement amount is doubled. When printing is performed with continuous conveyance, if the paper conveyance speed is shifted to the low speed side, the cycle of output of the movement amount becomes long, and the cycle for determining the movement speed also becomes long. If the moving speed can only be grasped in a long span, it becomes difficult to perform stable printing by performing appropriate feedback control on the moving speed of the paper that can fluctuate in real time.

  On the other hand, when trying to determine the amount of movement of the print medium in a certain movement section, the method of Patent Document 2 integrates all the amounts of movement in each period, so the accumulated amount of errors also increases, and movement There is concern about the quantity detection accuracy.

  The present invention has been made in view of the above, and an object of the present invention is to detect a movement amount with high accuracy while suppressing an output cycle of a movement amount of a medium such as a sheet from becoming longer.

The present invention is used in a printing apparatus including a transport unit that transports a print medium and a print unit that performs printing on the print medium, and the surface of the moving print medium transported by the transport unit is A detection device that images a plurality of times at different timings by an imaging unit, and detects a movement amount of the print medium conveyed by the conveyance unit based on a plurality of captured images corresponding to each timing, each of the plurality of captured images On the other hand, as the print medium detection process, the pattern matching using a part of the captured image obtained by imaging before the captured image to be processed as a template and the printing based on the position of the target image of the identified target image First generation means for performing a process of detecting a movement amount of the medium and generating first information indicating the detected movement amount;
If the movement amount indicated by the first information is not larger than a predetermined amount based on the first information, the template of the detection process for the next processed image is determined for the previously processed captured image. If the movement amount indicated by the first information is larger than a predetermined amount without changing from the used template, the template for the detection process for the next processed image is set to the previously processed captured image. A changing unit that changes from a used template to another template, and a second generation that generates whether or not the changing unit has changed the template of the detection process for the captured image to be processed next. Means, and output means for outputting data including the first information and the second information about the detection processing for each of the plurality of images, and the second information The first information of the data indicating that the template has not been changed by the changing means is not used for obtaining the cumulative information indicating the cumulative transport amount of the print medium by the transport, and the second information is the The detection apparatus characterized in that the first information obtained from data indicating that the template has not been changed by the changing means is used to acquire cumulative information indicating a cumulative transport amount of the print medium by the transport. It is.

  According to the present invention, it is possible to suppress the output cycle of the movement amount of a medium such as paper from being lengthened and detect the movement amount with high accuracy.

FIG. 6 is a schematic diagram for explaining a flow of pattern matching processing according to the first embodiment. FIG. 6 is a schematic diagram for explaining a flow of pattern matching processing according to the first embodiment. It is a block diagram which shows the structure of the movement amount sensor of Embodiment 1. FIG. Main part block diagram. 5 is a flowchart for explaining a flow of processing for obtaining a movement amount and a conveyance speed from an output result in the first embodiment. 5 is a flowchart for explaining a flow of processing for obtaining a movement amount and a conveyance speed from an output result in the first embodiment. FIG. 6 is a schematic diagram for explaining a full-line type printing apparatus according to a second embodiment. 1 is a perspective view showing an internal configuration of an ink jet printing apparatus according to Embodiment 1. FIG. FIG. 2 is a block diagram for explaining a control system of the ink jet printing apparatus according to the first embodiment. It is a schematic diagram for demonstrating the flow of the pattern matching process in a prior art.

  FIG. 7 is an external perspective view showing an outline of the configuration of an ink jet printing apparatus that performs recording using an ink jet print head (hereinafter, print head) according to an embodiment of the present invention. FIG. 8 is a block diagram showing an outline of a control system of the apparatus.

  As shown in FIG. 7, the printing apparatus 1 has an inkjet head 3 (hereinafter, head 3) that performs recording by discharging ink in accordance with print data from a host apparatus 610 (described later). Recording is performed by reciprocating in the direction.

  The printing medium P such as recording paper is fed through the paper feeding mechanism 5, transported to the recording position, and recording is performed by ejecting ink from the head 3 to the printing medium P at the recording position.

  In addition to mounting the head 3 on the carriage 2 of the printing apparatus 1, an ink tank 6 for storing ink to be supplied to the head 3 is mounted. The ink tank 6 is detachable from the carriage 2.

  The printing apparatus 1 shown in FIG. 7 is capable of color recording. For this reason, the carriage 2 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. An ink cartridge is installed. These four ink cartridges are detachable independently.

  The head 3 is a print head capable of printing a width of 1 inch at a time, adopts an ink jet system that ejects ink using thermal energy, and includes an electrothermal transducer (not shown).

  The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  In the printing apparatus 1 according to the present embodiment, a detection apparatus 4 is installed on the downstream side of the head 3 in the conveyance direction of the printing medium P so that the printing medium P can be imaged from below the surface opposite to the printing surface. Has been.

  During the printing operation, printing with a width of 1 inch is performed by scanning the carriage 2, and then a roller for supporting the printing medium P is rotated by driving the carry motor M <b> 2 to carry 1 inch.

  As shown in FIG. 8, the controller 600 includes an MPU 601, ROM 602, special purpose integrated circuit (ASIC) 603, RAM 604, system bus 605, A / D converter 606, signal input / output I / O device 607, and the like. The

  Here, the ROM 602 stores a program corresponding to a control sequence to be described later, a required table, and other fixed data.

  The ASIC 603 generates control signals for control of the carriage motor M1, control of the transport motor M2, and control of the head 3.

  The RAM 604 is used as a development area for image data, a work area for program execution, and the like. A system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data.

  The A / D converter 606 inputs analog signals from the sensor group described below, performs A / D conversion, and supplies a digital signal to the MPU 601. An interface with a switch group 620 (described later) and the detection device 4 is supplied to the MPU 601 via the I / O device 607 and the system bus 605.

  In FIG. 8, reference numeral 610 denotes a host device corresponding to the host or MFP shown in FIG. Image data, commands, status, and the like are transmitted and received by packet communication between the host device 610 and the printing device 1 via an interface (I / F) 611.

  Note that a USB interface may be further provided as the interface 611 separately from the network interface so that bit data and raster data transferred serially from the host can be received.

  Reference numeral 620 denotes a switch group, which includes a power switch 621, a print switch 622, a recovery switch 623, and the like.

  Reference numeral 630 denotes a sensor group for detecting a device state, and includes the detection device 4 and the temperature sensor 632 according to the present invention. In this embodiment, in addition to this, a photo sensor (not shown) for detecting the remaining amount of ink is provided.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, and 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the print medium P.

  The ASIC 603 transfers data for driving a printing element (ejection heater) to the print head while directly accessing the storage area of the RAM 604 during printing scanning by the head 3. In addition, the printing apparatus includes a display unit including an LCD and an LED as a user interface. The printing apparatus may be an electrophotographic printing apparatus.

(Embodiment 1)
FIG. 1 is a diagram for explaining the movement amount detection processing of the present embodiment. Illumination 12 (FIG. 3) is applied to the print medium, and the moving print medium is periodically imaged a plurality of times, and a plurality of captured images are captured at different timings such as image 0, image 1, image 2. Get.

  In the present embodiment, the conveyance direction of the print medium is from left to right in FIG. A part of each image obtained by imaging the back surface of the print medium at different timings is cut out. Here, an area of “vertical 5 pixels, horizontal 5 pixels” is cut out from the vicinity of the left end of image 0 as a template. Then, pattern matching is performed using the template, and the procedure for creating the next template is repeated when the matching point is near the right end.

  First, template 0 is created from image 0 in the first cycle. The template is stored in a template memory 14 (FIG. 3) described later.

  Next, pattern matching between the image 1 to be processed and the template 0 is performed in the next cycle to specify a target image, and a movement amount and a template identifier code are output from the position of the specified target image. If the template does not change in the next pattern matching, 0 is output as the identifier code. Here, SAD, SSD, or the like can be used as pattern matching processing. SAD is a method for obtaining a sum of absolute values of differences between pixel values of a template image and pixel values of an image obtained by imaging as a correlation value, and SSD is a method for obtaining a square sum of differences as a correlation value. A normalized cross-correlation method can also be used. This is calculated by subtracting the average value of the luminance values of the template and the target image from the luminance values of the respective pixels, so that the similarity can be calculated stably even if there is a variation in brightness.

  Next, pattern matching is performed between the image 2 to be processed and the template 0 in the next cycle, and the carry amount data and the template identifier 0 are output from the pixel position of the coincidence point.

  Next, pattern matching between the image 3 and the template 0 is performed in the next cycle, the carry amount data is output from the pixel position of the coincidence point, and since the coincidence point reaches the right end of the image area, the template is newly added from the image 3. 3 is created. Since the next template has been changed, identifier 1 is output. Template 3 is stored in template memory 14.

  Next, pattern matching between the image 4 and the template 3 is performed in the next cycle, the carry amount data is output from the pixel position of the coincidence point, and since the coincidence point reaches the right end of the image area, the template is newly added from the image 4. When 4 is created, identifier 1 is output. Thereafter, the same is repeated.

  Further, in this embodiment, each pixel is expressed by binary values of white or black for easy explanation. However, in actuality, imaging is performed with a multi-value image of 256 gradations (8 bits) and the like on the surface layer of the print medium. Pattern matching in the state of fibers, wrinkles, scratches, etc. is performed to find the most consistent point.

  In addition, although the surface layer of the print medium is described for convenience of explanation, the structure inside the print medium is imaged on the surface layer using a transmission light source installed on the opposite side of the image sensor 11 so as to transmit the print medium. May be.

  The template is created from the right end of the captured image 0 when the printing medium is moved (conveyed) from the right to the left from the stopped state, and is centered when the moving (conveying) direction is unknown. Cut out to include.

  FIG. 2 is a timing chart of the detection process of the present embodiment. In FIG. 2, F0, F1,... Are the starting points of the imaging frames determined periodically in advance. The distance between each starting point is the movement amount by the conveyance of the area calculated | required by pattern matching.

  In F1, the image 1 is acquired, and the movement amount from F0 to F1 is obtained by pattern matching with the template 0 created from the image 0 captured in F0. Further, the obtained movement amount (= 0.5) is set as the first information, an identifier (= 0) for identifying the template at this time is added as the second information, and the information is output as output 0. Of each output in the figure, the value on the left is the movement amount, and the value on the right is the identifier.

  In F2, the image 2 is acquired, and the movement amount from F0 to F2 is obtained by pattern matching with the template 0 created from the image 0 captured in F0. Further, the obtained movement amount (= 0.5) and an identifier (= 0) for identifying the reference template are added, and information is output as output 2.

  Next, in F3, the image 3 is picked up, and the carry amount from F0 to F3 is obtained by pattern matching with the template 0. Since this movement amount exceeds a predetermined value (1.3 mm as an example), the template is updated to the one created from the image 3 along with the movement amount output, and the template is updated. An identifier (= 1) is added and information is output as output 3.

  The transport amount from F0 to F3 is not the value obtained for each imaging period of F0 to F1 (0.5 mm), F1 to F2 (0.5 mm), and F2 to F3 (0.5 mm). A value obtained by directly obtaining the movement amount from F0 from the image taken at the point F3 is employed. It is obtained by selecting the latest value from the output data subjected to pattern matching with the same template.

  Similarly, pattern matching between the image captured at F4 and the template 3 is performed, information is output as the output 4, pattern matching between the image captured at F5 and the template 4 is performed, and information is output as the output 5.

  The prescribed value for changing the template described above may be a fixed value determined in advance, but in consideration of transport control parameters such as transport speed or maximum acceleration, the area of the image sensor 11 is projected in the next cycle. It can be set appropriately so that there is no.

  FIG. 3 is a block diagram showing the configuration of the transport amount detection system mounted on the detection device 4 of this embodiment.

  In FIG. 3, the fixed-cycle timer 10 creates a reference signal for calculating the carry amount when the image sensor 11 picks up an image of the print medium surface layer at a fixed cycle (for example, 1 msec).

  The illumination 12 is illumination means such as an LED for imaging the surface layer of the print medium, and the image memory 13 is a volatile memory for temporarily storing an image output from the imaging sensor 11. The template memory 14 is a volatile memory that stores an image comparison template that serves as a reference for carrying amount detection. When the template is updated, the FLUG 15 is set.

  The pattern matching unit 16 detects the most matched location by a method known as SSD, SAD, or ZNCC, and obtains the amount of movement by conveyance from the position of the image that matches the template in the captured image.

  The specified value stored in the specified value storage unit 17 is a threshold value for using the imageable area of the image sensor 11 as widely as possible. The comparison unit 18 calculates the movement amount obtained by the pattern matching unit 16 and the specified value. Make a comparison. When the movement amount exceeds this specified value, a signal indicating that the template is to be changed is output to the template memory 14. Upon receiving this, the template memory 14 creates a new template from another image obtained from the image memory 13 and stores it. Then, this is transmitted to the pattern matching unit 16. It is determined that the transport amount is sufficient from the image.

  When it is determined that the carry amount is sufficient, the contents of the template memory 14 are updated to the contents created from the image that is the comparison target at that time, and the identifier generation unit 15 is further set. If the template is not updated, the identifier generation unit 15 is cleared.

  The identifier generation unit 15 is output as an identifier that is output together with the output of the transport amount data.

  The output unit 19 is an interface such as SPI or I2C for outputting the conveyance amount and the identifier to the controller 600.

  With reference to the flowcharts shown in FIG. 2, FIG. 3, and FIG. 4, the flow of detection processing of this embodiment will be described.

  First, in the imaging cycle F0 shown in FIG. 2, the printing medium is imaged at the time of F0 when the conveyance is stopped (step S0).

  Next, the captured image is read into the image memory 13 (step S1).

  In step S2, since the template is empty at the start of activation of the apparatus and pattern matching cannot be performed, the process proceeds to step S3 and 0 is set as the carry amount.

  Next, the process proceeds to step S7, where the template memory 14 creates a template from the image 0, saves it, and updates the template (step S7).

  Next, the process proceeds to step S8, and since the template has been updated in the previous step 7, the carry amount L is cleared and the identifier (ID) = 1 is set.

  Finally, the conveyance amount and identifier = 1 are output from the output unit 19 (step S9).

  Next, processing of the image 1 captured in the imaging cycle F1 and the image 2 captured in the imaging cycle F2 will be described. First, in step S0, the print medium is imaged at the timing of the imaging cycle F1, as in the case of F0.

  Next, in step S1, the captured image is read into the image memory 13, and the process proceeds to step S4 because it is not at the start of activation of the apparatus.

  Next, in step S4, the pattern matching unit 16 obtains the carry amount L from the deviation amount of the feature points. At this time, not only the shift amount in pixel units but also the shift amount in pixel units or less may be obtained using the estimation means.

  Next, in step S5, the conveyance amount L is set and transmitted to the comparison unit, and the ID is cleared.

  Next, in step S6, the comparison unit 18 proceeds to step S9 because the specified value (value indicating 1.3 mm) already acquired from the specified value storage unit 17 and the detected transport amount L do not exceed the specified value. The output unit 19 outputs the carry amount L and the identifier ID = 0 acquired from the pattern matching unit 16 to the controller 600 of the printer.

  Below, the image 3 imaged with the imaging period F3 is demonstrated.

  First, the print medium at the time point F3 is imaged (step S0), and then the captured image is read into the image memory 13 (step S1). Since it is not the start time of the apparatus (step S2), the process proceeds to step S4. .

  The pattern matching unit 16 determines L as the conveyance amount from the deviation amount of the feature points. At this time, not only the shift amount in pixel units but also the shift amount in pixel units or less can be obtained using the estimation means.

  Next, in step S5, the conveyance amount L is set and transmitted to the comparison unit, and the ID is cleared.

  Next, in step S6, the comparison unit 18 has already obtained the specified value from the specified value storage unit 17 and the detected transport amount L exceeds the specified value, so the process proceeds to step S7. In step S7, the template memory 14 creates a template from the image 3, saves it, and updates the template.

  Next, the process proceeds to step S8, and since the template has been updated in the previous step 7, the carry amount L is cleared and the identifier (ID) = 1 is set.

  Finally, the conveyance amount and identifier = 1 are output from the output unit 19 (step S9).

  Similarly, the images 4, 5 and 6 imaged after the imaging cycle F4 are processed according to the flow of FIG.

  FIG. 5 is a flowchart for explaining a procedure in which the controller 600 of the printing apparatus 1 receives a signal output from the movement amount detection apparatus of the present embodiment and obtains the conveyance amount and conveyance speed of the print medium. Here, the MPU 601 and the ROM 602 in the controller 600 serve as an information processing unit for obtaining the conveyance amount and the conveyance speed.

  When the head 3 capable of printing a width of 1 inch at a time is used in the serial printing type printing apparatus 1 as shown in FIG. 1 inch. Under this assumption, the following explanation will be given.

  In FIG. 5, the imaging cycle is t, the total transport amount in one transport is Lsum, the total transport amount before the template is updated is Lsum_old, and the identifier before the cycle is ID_old. Further, the transport amount for each cycle is L_d, the transport speed for each cycle is V_d, and the transport amount for the previous cycle with the same template is L_old.

  Note that the printing apparatus writes these calculated values in the RAM 604, and is set to 0 as an initial value immediately before the start of conveyance.

  First, processing using output results for images 0 to 2 captured in the imaging cycles F0 to F2 will be described with reference to the flowchart of FIG.

  First, in step S20, the signal is input from the controller 600 or activated by a user operating an activation switch provided separately in the movement amount detection device.

  In step S <b> 21, data including the movement amount L and the identifier ID output from the output unit 19 is received and stored in the RAM 604.

  In step S22, the MPU 601 determines whether ID_old = 1. In the output result corresponding to the imaging cycles F0 to F2, since ID_old = 0, the process proceeds to S24.

  In step S24, the MPU 601 obtains the transport amount in each cycle (F0, F1, F2). Since the transport amount for each cycle is a difference from the output in the previous cycle, L_d = L−L_old.

  In step S25, the MPU 601 obtains V_d = L_d / t as the transport speed and stores it in the RAM 604 as speed information. t is an imaging period, and a value output from the output unit 19 may be stored in the RAM 604. In this way, the conveyance speed L can be obtained in each cycle by using the identifiers of 0 and 1.

  Next, in step S <b> 26, the MPU 601 obtains a total transport amount L_sum = L + Lsum_old, which is a cumulative transport amount of the print medium, and stores it in the RAM 604 as cumulative information.

  In step S27, the MPU 601 determines whether ID_old = 1. Since the ID_old = 0 for the images captured in the imaging periods F0 to F2, the process proceeds to step S29.

  Next, in step S29, the value of the transport amount L_old is set to L from the same template, written in the RAM 604, and this L_old is used in the next cycle.

  Next, in step S30, the identifier ID_old = ID is set and written in the RAM 604, which is used in the next cycle.

  Below, the process about the output corresponding to the image 3 imaged with the imaging period F3 is demonstrated below.

  First, Step S20 to Step S26 are the same as the processing for the output result corresponding to the imaging cycles F0 to F2.

  Next, since the identifier ID is 1 in step S27, the process proceeds to step S28. In step S28, output with the same template ends in this cycle, so Lsum_old is changed to Lsum obtained in step S26 and stored in the RAM. Since the template changes from the next cycle, it is stored in the RAM 604 as L_old = 0 and used as a reference in the next cycle. Here, the process proceeds to step S28 and Lsum_old is changed only when ID = 1. Therefore, the transport amount for each cycle is not accumulated, and only the maximum L among the L detected by the same template is accumulated. Therefore, even when the transport speed is slow, the cumulative number of times for obtaining the total transport amount can be suppressed, and the accumulation of movement amount detection errors can be reduced.

  Similarly, an output corresponding to an image picked up after the image pickup period F4 is processed in the flow from step S21.

  In the above description, the identifier ID has been described as being 1 at the output of the update period of the template. Any change can be used as long as the change can be identified, such as 0.

  A method of applying the transport amount detection method of the above embodiment in the serial printer shown in FIGS. 7 and 8 will be further described.

  At the time of the printing operation, printing with a width of 1 inch is performed by scanning the carriage 2, and then the printing medium P is conveyed by 1 inch by driving the conveyance motor M2. At this time, first, 0.95 inch conveyance is performed at high speed, and then the remaining 0.05 inch conveyance is performed at low speed.

  In the first high-speed conveyance, the detection device 4 described above is used to image the surface of the print medium and perform a movement amount detection process. The detected movement amount is output as needed together with the identifier (ID). At this time, the rotation of the roller that conveys the print medium P is detected by an encoder (not shown). The controller 600 receives a signal from the encoder, and sends a signal for rotating the transport motor M2 to the transport motor driver 642 based on the received signal. In the 0.95-inch conveyance, the controller 600 can calculate the total conveyance amount Lsum that conveys the print medium P, but does not particularly provide feedback to the control of the conveyance motor M2.

  In the next conveyance for 0.05 inch, similarly, the surface of the print medium is imaged by using the detection device 4 and the movement amount detection process is performed. During the conveyance, the total conveyance amount Lsum is detected as needed from the output movement amount and the identifier (ID), and feedback to the control of the conveyance motor M2 is performed. Then, when the print medium has just moved by one inch, the conveyance motor M2 is controlled so that the movement of the print medium is stopped, so that the conveyance can be performed with high accuracy.

(Second Embodiment)
FIG. 6 is a schematic diagram illustrating a printing apparatus according to the second embodiment, and is a view of the printing apparatus viewed from the side. This printing apparatus has a full line type head capable of printing the width of a printing medium (direction passing through the drawing) at a time.

  As shown in FIG. 6, the printing apparatus includes a full-head type print head 21 having nozzles of four colors Y, M, C, and BK, and a conveyance roller 22 for continuously conveying the print medium in the F direction. Yes. Further, during printing with the roll-shaped print medium 24, it is possible to rotate the counterclockwise direction and feed the print medium, while applying a rotational force in the clockwise direction. During printing, back tension is applied to the print medium P in the R direction by holding the roll-shaped print medium 24 with a weak rotational force in the clockwise direction. As a result, the print medium P is held horizontally under the print head 21.

  In the printing apparatus of the present embodiment, recording is performed by giving a drive signal to the full-line type print head 21 while continuing to convey the print medium P by the conveyance roller 22.

  In this printing apparatus, it is considered that the influence on the printing length due to speed fluctuation is large. For example, if the 1-percent speed is fast, the length of the maximum 0.1-inch print area becomes long for a 10-inch print.

  In the present embodiment, both the carry amount and the carry speed are detected based on the movement amount information output by the detection device 4. For example, assuming 0.5-inch printing as one cycle, the error between the transported length for each 0.5-inch printing and the normal printing length is obtained. • Correct the average printing speed so that the error is canceled at the next printing cycle. On the other hand, the conveyance speed is obtained at a cycle shorter than 0.5 inch printing. Based on the obtained transport speed, an ejection trigger signal for determining the ejection timing of ink from the print head 21 is generated.

  In the embodiment described above, each of the processing of the template memory 14, the pattern matching unit 16, the comparison unit 18, the specified value storage unit 17, and the output unit 19 in the detection device 4 may be configured by a circuit including a CPU. One CPU may execute the function of each unit. Further, a program for the CPU to execute the function of each unit may be stored in a non-volatile medium such as a CD, a Blu-ray, or a USB memory, read by a computer, and executed.

Claims (11)

A surface of a moving print medium that is used for a printing apparatus that includes a conveyance unit that conveys the print medium and a printing unit that performs printing on the print medium is different depending on the imaging unit. A detection device that captures a plurality of times at a timing and detects a movement amount of the print medium transported by the transport unit based on a plurality of captured images corresponding to each timing,
For each of the plurality of captured images, as the print medium detection process, pattern matching using a part of the captured image obtained by imaging before the captured image to be processed as a template, and the target image of the identified target image First generation means for performing a process of detecting the amount of movement of the print medium based on the position of the first medium, and generating first information indicating the detected amount of movement;
If the movement amount indicated by the first information is not larger than a predetermined amount based on the first information, the template of the detection process for the next processed image is determined for the previously processed captured image. If the movement amount indicated by the first information is larger than a predetermined amount without changing from the used template, the template for the detection process for the next processed image is set to the previously processed captured image. Change means to change from the template used to another template,
Second generating means for generating second information indicating whether or not the template of the detection process for the captured image to be processed next has been changed by the changing means;
Output means for outputting data including the first information and the second information about the detection processing for each of the plurality of images,
The first information of the data indicating that the second information has not been changed by the changing unit is not used for obtaining the cumulative information indicating the cumulative transport amount of the print medium by the transport. The second information is used for acquiring cumulative information indicating the cumulative transport amount of the print medium by the transport using the first information obtained from data indicating that the template has not been changed by the changing means. A characteristic detection device.   Regarding the data output by the output means, the first information of the data indicating that the second information has been changed by the changing means and the second information has not been changed by the changing means. Speed information indicating the speed of the print medium transported by the transport means is acquired using the first information of the data indicating that the second information has not been changed by the changing means in the template. The first information of the print medium is not used, and the second information uses the first information of the data indicating that the template has not been changed by the changing unit. A detection apparatus, further comprising an information processing unit that acquires cumulative information indicating a conveyance amount.   The apparatus according to claim 2, further comprising: a conveyance control unit configured to control conveyance of the print medium by the conveyance unit according to at least one of the speed information and the accumulated information.   The output unit outputs the data to an information processing unit of the printing apparatus, and the information processing unit includes the first information of data indicating that the second information has been changed by the changing unit. The second information uses the first information of the data indicating that the template has not been changed by the changing unit, respectively, and acquires speed information indicating the speed of the print medium conveyed by the conveying unit. The second information has not been changed by the changing means without using the first information obtained from the detection process indicating that the changing means has not changed the template. 2. The detection according to claim 1, wherein cumulative information indicating the cumulative transport amount of the print medium is acquired using the first information obtained from the detection process indicating Location.   5. The printing apparatus according to claim 4, further comprising: a transport control unit configured to control transport of the print medium by the transport unit according to at least one of the speed information and the accumulated information. The detection device described.   2. The detection process according to claim 1, wherein the target image is specified by using a sum of absolute values of differences between pixel values of a template and pixel values of the captured image or a sum of squares of the differences as a correlation value. The detection device according to any one of 5.   The detection device according to claim 1, wherein the detection process specifies the target image using a normalized cross-correlation method.   The detection apparatus according to claim 1, further comprising the imaging unit.   The detection apparatus according to claim 1, wherein the printing unit includes an ink jet print head for performing printing on the print medium by ejecting ink.   The first information of data indicating that the second information is a template change by the changing means, and the first information of data indicating that the second information is not changed of the template by the changing means 10 is used for acquiring speed information indicating the speed of the print medium by the conveyance. A surface of a moving print medium that is used for a printing apparatus that includes a conveyance unit that conveys the print medium and a printing unit that performs printing on the print medium is different depending on the imaging unit. It is a detection method of capturing a plurality of times at a timing and detecting a movement amount of the print medium transported by the transport unit based on a plurality of captured images corresponding to each timing,
For each of the plurality of captured images, as the print medium detection process, pattern matching using a part of the captured image obtained by imaging before the captured image to be processed as a template, and the target image of the identified target image A first generation step of performing a process of detecting a movement amount of the print medium based on the position of the print medium, and generating first information indicating the detected movement amount;
If the movement amount indicated by the first information is not larger than a predetermined amount based on the first information, the template of the detection process for the next processed image is determined for the previously processed captured image. If the movement amount indicated by the first information is larger than a predetermined amount without changing from the used template, the template for the detection process for the next processed image is set to the previously processed captured image. Change process to change from the template used to another template,
A second generation step of generating second information indicating whether the change step has changed the template of the detection process for the captured image to be processed next;
An output step of outputting data including the first information and the second information about the detection processing for each of the plurality of images,
The second information is obtained from data indicating that the template has not been changed by the changing means without using the first information of the data indicating that the template has not been changed. A detection method characterized by acquiring cumulative information indicating a cumulative transport amount of the print medium by the transport using one information.

Images