Recording apparatus and method for controlling the same

Abstract

To provide a recording device that is able to appropriately control the accuracy of detection of a sheet end.SOLUTION: A recording device of the present invention includes: conveying means that conveys a sheet in a conveying direction; a carriage that moves recording means in a width direction of the sheet; detection means that is mounted on the carriage and detects a first end of the sheet in the width direction and a second end different from the first end; and control means that allows the detection means to detect the first end and the second end of the sheet until a cumulative amount of conveyance of sheet reaches a first amount of conveyance. When the cumulative amount of conveyance of the sheet reaches the first amount of conveyance, the control means executes second control for allowing the first end to be detected without allowing the second end to be detected until the cumulative amount of conveyance of the sheet reaches the second amount of conveyance; and when the cumulative amount of conveyance of the sheet reaches the second amount of conveyance, the control means executes third control for allowing the second end to be detected.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a recording apparatus and a method for controlling the recording apparatus. [Background technology]

[0002] In a recording device that records an image by ejecting ink onto a sheet, the amount of ink ejected outside the sheet during borderless recording can be minimized by detecting the edges of the sheet. Patent Document 1 discloses a recording device equipped with a carriage equipped with a detection means for detecting the edges of the sheet. In this recording device, edge detection is performed on both ends of the sheet during the first main scan, and edge detection is performed on only one edge of the sheet during the second and subsequent main scans. As a result, the throughput when recording an image on a sheet can be improved compared to when edge detection on both ends of the sheet is performed every time with each main scan. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-90316 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, a method in which both ends are detected in the first main scan and only one end is detected in the second or subsequent main scans cannot deal with uneven sheet widths caused by sheet distortion due to a humid environment or sheets with poor accuracy, etc. An object of the present invention is to provide a recording device that can appropriately control the accuracy of sheet edge detection even when the sheet width is uneven. [Means for solving the problem]

[0005] The recording device of the present invention is a recording device comprising a conveying means for conveying a sheet in a conveying direction, a recording means for recording an image by ejecting liquid onto the sheet conveyed by the conveying means, a carriage for moving the recording means in a width direction of the sheet that intersects the conveying direction, a detection means mounted on the carriage for detecting a first end of the sheet in the width direction and a second end different from the first end, and a control means for executing a first control to cause the detection means to detect the first end and the second end of the sheet until the accumulated conveying amount of the sheet reaches a first conveying amount, wherein the control means executes a second control to cause the first end to be detected without detecting the second end after the accumulated conveying amount of the sheet reaches the first conveying amount until the accumulated conveying amount of the sheet reaches the second conveying amount, and executes a third control to cause the second end to be detected when the accumulated conveying amount of the sheet reaches the second conveying amount. Effect of the Invention

[0006] According to the present invention, it is possible to provide a recording apparatus capable of appropriately controlling the accuracy of sheet edge detection. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the internal configuration of a recording apparatus. [Diagram 2] FIG. 2 is a diagram showing a configuration of a recording head. [Diagram 3] FIG. 2 is a block diagram showing the configuration of a control system of the printing apparatus. [Figure 4] FIG. 4 is a diagram showing the arrangement of a detection sensor relative to a carriage. [Diagram 5] 13 is a diagram showing a moving distance of the carriage when edge detection is performed on only one side. FIG. [Figure 6] 13 is a diagram showing the moving distance of the carriage when detecting both ends. FIG. [Figure 7] FIG. 13 is a diagram showing a moving distance of the carriage when B-side preliminary ejection is performed. [Figure 8] FIG. 13 is a diagram illustrating an example of a flowchart of a process for performing borderless printing. [Figure 9] FIG. 13 is a diagram illustrating an example of a flowchart of a process for performing borderless printing. [Figure 10] FIG. 1 is a diagram for explaining a location where an edge of a sheet is detected; [Figure 11] 13 is a diagram illustrating an end position in a section of a conveyance amount Y1. FIG. [Figure 12] FIG. 13 is a diagram illustrating an example of a flowchart in the case where the recording environment is reflected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings. Note that the following embodiment does not limit the present invention, and not all of the combinations of features described in the present embodiment are necessarily essential to the solving means of the present invention. In addition, in the present embodiment, an inkjet recording apparatus will be described as an example of the recording apparatus.

[0009] <Recording device> An inkjet printing apparatus (hereinafter, printing apparatus 100) according to an embodiment of the present invention will be described with reference to Figures 1 to 4. Figure 1 is a diagram showing the internal configuration of the printing apparatus 100. Figure 2 shows the configuration of a print head 10. Figure 3 is a diagram showing the block configuration of a control system in the printing apparatus 100. Figure 4 is a top view for explaining the arrangement of a detection sensor 401.

[0010] The supply unit 101 supplies a sheet, which is a recording medium, into the apparatus body. The sheet transport unit 103, which is a sheet transport means, guides the sheet supplied from the supply unit 101 to a predetermined recording position, and also guides the sheet from the recording position to the discharge unit 102. The recording unit includes a carriage 105 supported by a carriage shaft 104 so as to be movable in the main scanning direction (X direction), and a recording head 10 (see FIG. 2) detachably mounted on the carriage 105. The recording head 10 has nozzles arranged therein for ejecting ink, which is a liquid, to record an image on the sheet. The recovery unit 108 performs a recovery process for the recording head 10. The main scanning direction is a direction intersecting (orthogonal to) the transport direction in which the sheet is transported. In the main scanning direction, the side of the recovery unit 108 is the reference side in the width direction of the sheet. Here, the sheet will be described as a cut sheet, but it may be a rolled sheet.

[0011] The carriage 105 is provided with a carriage cover 106 for engaging with the carriage 105 and guiding the recording head 10 to a predetermined mounting position on the carriage 105, and a head set lever 107. The head set lever 107 engages with a tank holder 113 of the recording head 10 and presses the recording head 10 to set it at a predetermined mounting position. A head set plate (not shown) that is spring-biased against an engagement portion with the recording head 10 is provided on the upper part of the carriage 105 so as to be rotatable about a head set lever shaft. The head set lever 107 is configured to mount the recording head 10 on the carriage 105 while pressing the recording head 10 by the spring force. The carriage 105 is provided with a detection sensor 401. The detection sensor 401 is a sensor that measures the light reflection level of the sheet and detects the edge of the sheet. The position of the carriage 105 can be obtained by using a linear encoder (not shown). In other words, the position where the light reflection level changes is the position of the edge of the sheet. The detection means can detect the edge of the sheet from the output of the detection sensor and the output of the linear encoder.

[0012] FIG. 2 is a diagram showing the configuration of the recording head 10. The recording head 10 is a side shooter type that ejects ink in a direction substantially perpendicular to the heater substrate. The recording head 10 includes a recording element unit 111, an ink supply unit 112, and a tank holder 113. The recording element unit 111 includes a first recording element 114, a second recording element 115, a first plate 116, an electric contact substrate 119, and a second plate 117. The first plate 116, which requires flatness accuracy because it affects the ink ejection direction, is made of alumina (Al2O3) material with a thickness of 0.5 to 10 mm. The second plate 117 is a single plate-like member with a thickness of 0.5 to 1 mm, and is laminated and fixed to the first plate 116 via an adhesive. The first recording element 114 and the second recording element 115 are adhesively fixed to the surface of the first plate 116.

[0013] Next, the CPU 301, which is a control means, can access a flash ROM 303 that stores an updatable control program or processing program, and an EEPROM 304 that stores various constant data, etc. The CPU 301 can also access a RAM 302 for storing command signals and image information received from a host PC (not shown) via a USB control unit 316 and a network control unit 317. The CPU 301 controls the printing operation based on the information stored in these memories and the detection results of various sensors for detecting the state of the printing device connected to an input / output port 305.

[0014] The CPU 301 operates the carriage motor 309 via the input / output port 305 and the carriage motor control unit 307 to move the carriage 105. The CPU 301 also operates the conveying motor 308 via the input / output port 305 and the conveying motor control unit 306 to operate the sheet conveying unit 103, such as the conveying rollers of the conveying unit 103. The CPU 301 also controls the band memory control unit 312 and the recording head control unit 314 based on various information stored in the RAM 302 to drive the recording head 10, thereby recording a desired image on the sheet. The band memory control unit 312 controls the reading and writing of the memory 313 used when recording an image in band units using the recording head 10. Instruction information input from the keys of the operation panel 319 is transmitted to the CPU 301 via the operation panel control unit 318. Similarly, the LED lighting and LCD display of the operation panel 319 are controlled via the operation panel control unit 318 by commands from the CPU 301.

[0015] The LED drive circuit 323 turns on and off the LED 325 built into the detection sensor 401 according to commands from the CPU 301. The I / V conversion circuit 322 converts the current output, which varies depending on the intensity of light received by the phototransistor 324, into a voltage. The amplifier circuit 321 amplifies the output of the phototransistor 324, which has been converted into a voltage value, so that it becomes an optimum voltage level for A / D conversion. The A / D conversion circuit 320 converts the amplified output of the phototransistor 324 (output of the amplifier circuit 321) into a 10-bit digital signal. The gain level of the amplifier circuit 321 is adjustable, and the CPU 301 monitors the amplifier circuit output voltage level and can adjust the gain and the current supplied to the LED to the optimum voltage level.

[0016] The CPU 301 and its peripheral circuits are generally integrated as a system on a chip (SoC) for the purposes of reducing costs, reducing power consumption, and increasing speed. In this embodiment, the CPU 301, the USB control unit 316, the band memory control unit 312, and the input / output port 305 are integrated into one IC as the SoC.

[0017] <Sheet edge detection> FIG. 4 is a top view for explaining the arrangement of the detection sensor 401. The detection sensor 401 is arranged on the A side, which is the reference side in the main scanning direction (X direction) with respect to the carriage 105, and is arranged on the upstream side of the conveying direction (Y direction) of the sheet 402 with respect to the recording head 10. By arranging the detection sensor on the upstream side with respect to the recording head 10, the edge of the sheet can be detected in an unrecorded area where an image of the sheet is not recorded when an image is recorded by the recording head 10. The edge detection of the sheet 402 is performed when the carriage 105 moves from the inside of the sheet to the outside of the sheet in order to detect the edge stably. That is, when the carriage 105 moves in the return direction from the B side, which is the non-reference side, to the A side, which is the reference side, the detection sensor 401 detects the edge of the A side of the sheet 402. Conversely, when the carriage 105 moves in the forward direction from the A side, which is the reference side, to the B side, which is the non-reference side, the detection sensor 401 detects the edge of the B side of the sheet 402.

[0018] Here, the movement distance of the carriage 105 when edge detection on the B side is not performed and when edge detection on the B side is performed will be described with reference to Figs. 5 to 7. Fig. 5 shows the case when the edge on the B side is not detected, Fig. 6 shows the case when the edge on the B side is detected, and Fig. 7 shows the case when the edge on the B side is detected during preliminary ejection. When edge detection on the B side is not performed in the printing operation from the A side to the B side, it is not necessary to move the detection sensor 401 to the edge of the sheet on the B side. Therefore, the movement distance of the carriage 105 is the sheet width 801 plus the head width 802.

[0019] When detecting the edge of side B during a printing operation from side A to side B, the detection sensor 401 needs to move to the edge of the sheet on side B. For this reason, the movement distance of the carriage 105 is the sheet width 801, the head width 802, and the distance 901 between the head and the sensor.

[0020] Preliminary ejection on side B involves performing preliminary ejection that ejects ink that does not contribute to an image into a preliminary ejection port 810 provided on the platen. Therefore, when preliminary ejection is performed on side B, the carriage 105 needs to move to the preliminary ejection position. Therefore, the movement distance of the carriage 105 is the sheet width 801 and head width 802 plus the distance 1101 from the edge of the sheet on side B to the preliminary ejection position. For this reason, the movement distance of the carriage 105 is minimum when the edge on side B is not detected, and maximum when preliminary ejection is performed.

[0021] <About borderless printing> The borderless recording process will be described with reference to the flowcharts of FIG. 8 and FIG. 9. The flowchart of FIG. 8 is a process for detecting both ends (side A and side B) in the width direction from when the recording of an image on a sheet starts until the transport amount Y1 is reached. The flowchart of FIG. 9 is a process for detecting only the end on side A in the width direction from when the transport amount Y1 is reached until the transport amount Y2 is reached, and for detecting the end on side B when the transport amount Y2 is reached. The flowcharts of FIG. 8 and FIG. 9 are connected at C-1. The process related to recording is performed by the CPU 301 executing a program stored in the flash memory 303. The process is started when the recording device 100 receives recording data (recording job) of a borderless image from the host PC. Note that an example of receiving a recording job from the host PC will be described here, but the process may be performed when the CPU 301 acquires a recording job stored in the RAM 302 or the like. The user can select whether or not the recording device 100 reduces the process of detecting both ends by user settings. The processes of FIG. 8 and FIG. 9 are performed assuming that the process of detecting both ends is selected.

[0022] Processing begins when the printing device 100 receives print data for a borderless image from the host PC.

[0023] In step S500, the CPU 301 conveys the sheet to the recording start position by the sheet conveying unit 103. At this time, the detection sensor 401 detects the edge of the sheet on the A side, which is the reference side.

[0024] In step S501, the CPU 301 determines the transport amount Y1 of the section for detecting both ends of the sheet, and also clears the value of ΣY, which is the cumulative transport amount obtained by accumulating the reference transport amount for each scan, to zero. Note that the transport amount Y1 can be an integer multiple of the reference transport amount for each scan. Also, the transport amount Y1 and the transport amount Y2 can be selected by the user as variable or fixed for each recording.

[0025] In step S502, the CPU 301 determines whether the accumulated carry amount ΣY is equal to or less than the set carry amount Y1. If the accumulated carry amount ΣY exceeds the carry amount Y1, the process proceeds to step S516. If the accumulated carry amount ΣY is equal to or less than the carry amount Y1, the process proceeds to step S503.

[0026] In step S503, CPU 301 performs printing of an image corresponding to the nozzle length of print head 10 while scanning carriage 105 from the end on side A to the end on side B. In step S504, CPU 301 determines whether or not to perform preliminary ejection on side B. If preliminary ejection is not to be performed, CPU 301 further moves carriage 105 to an edge detection position that is outside the printing position on side B in step S505 (FIG. 6). If preliminary ejection is to be performed, CPU 301 moves carriage 105 to a preliminary ejection position that is outside the edge detection position in step S506 (FIG. 7).

[0027] In step S507, the CPU 301 executes control to cause the detection sensor 401 to detect the B-side edge of the sheet during the movement of the carriage 105. Then, in step S508, the CPU 301 determines whether the carriage 105 has moved to a designated position (the preliminary ejection position when preliminary ejection is executed, or the edge detection position when preliminary ejection is not executed). When the movement of the carriage 105 is completed, in step S509, the CPU 301 determines whether the carriage 105 is at the preliminary ejection position. If it is at the preliminary ejection position, in step S510, the print head 10 executes preliminary ejection. When preliminary ejection is finished or when the movement to the edge detection position is completed, in step S511, the CPU 301 calculates the sheet width using the previous detection position of the A-side edge and the detection position of the B-side edge detected in step S507.

[0028] In step S512, the CPU 301 causes the sheet conveying unit 103 to convey the sheet by the reference conveying amount, and adds the reference conveying amount of the sheet to the accumulated conveying amount ΣY.

[0029] In step S513, the CPU 301 executes printing of an image corresponding to the nozzle length of the print head 10 while scanning the carriage 105 from side B to side A. Furthermore, in step S514, the CPU 301 executes control to cause the detection sensor 401 to detect the end of side A during the movement of the carriage 105.

[0030] In step S515, the CPU 301 causes the sheet conveying unit 103 to convey the sheet by the reference conveying amount, and adds the reference conveying amount of the sheet to the accumulated conveying amount ΣY. When step S515 ends, the process returns to step S502.

[0031] In step S516, the CPU 301 sets the conveyance amount Y2 for the section where only one edge is detected, and sets the print width for borderless printing. In step S517, the CPU 301 clears the value of the accumulated conveyance amount ΣY to zero.

[0032] In step S518, CPU 301 performs printing of an image corresponding to the nozzle length of print head 10 while scanning carriage 105 from the end on side A to the end on side B. Next, in step S519, CPU 301 determines whether to perform preliminary ejection on side B. If preliminary ejection is to be performed, CPU 301 moves carriage 105 to a preliminary ejection position on the outer side of the end detection position on side B in step S520.

[0033] In step S521, it is determined whether the cumulative carry amount ΣY is smaller than the carry amount Y2. If the cumulative carry amount ΣY is smaller than the carry amount Y2, the process proceeds to step S530. If the cumulative carry amount ΣY is equal to or greater than the carry amount Y2, the carriage 105 is further moved from the recording position on side B to the edge detection position in step S522.

[0034] In step S523, the CPU 301 executes control to cause the detection sensor 401 to detect the edge of the sheet on side B during the movement of the carriage 105. Then, in step S524, the CPU 301 determines whether the carriage 105 has moved to a designated position (the preliminary ejection position when preliminary ejection is performed, or the edge detection position when preliminary ejection is not performed). When the movement of the carriage 105 is completed, in step S525, the CPU 301 determines whether the carriage 105 is at the preliminary ejection position. If it is at the preliminary ejection position, in step S526, the print head 10 performs preliminary ejection. When preliminary ejection is completed or the movement to the edge detection position is completed, in step S527, the CPU 301 calculates the sheet width using the immediately preceding detection position of the edge on side A and the detection position of the edge on side B in step S523.

[0035] In step S528, the CPU 301 causes the sheet conveying unit 103 to convey the sheet by the reference conveying amount, and clears the accumulated conveying amount ΣY to zero.

[0036] In step S529, the CPU 301 updates the conveyance amount Y2 and the print width for borderless printing as necessary. Note that the conveyance amount Y2 may be fixed for one sheet, or may be selected by user settings.

[0037] In step S530, the CPU 301 causes the sheet conveying unit 103 to convey the sheet by the reference conveying amount, and adds the reference conveying amount of the sheet to the accumulated conveying amount ΣY.

[0038] In step S531, the CPU 301 determines whether the recording is complete. If the recording is complete, the process proceeds to step S536, where the sheet on which the image is recorded is discharged. If the recording is not complete, the process proceeds to step S532. In step S532, the CPU 301 performs recording of an image corresponding to the nozzle length of the recording head 10 while scanning the carriage 105 from the end on side B to the end on side A.

[0039] In step S533, the CPU 301 executes control to cause the detection sensor 401 to detect the end of the carriage 105 on the A side during the movement of the carriage 105.

[0040] In step S534, it is determined whether recording has been completed. If recording has been completed, the process proceeds to step S536, where the sheet on which the image has been recorded is discharged. If recording has not been completed, in step S535, the CPU 301 causes the sheet conveying unit 103 to convey the sheet by the reference conveying amount, and adds the reference conveying amount to the accumulated conveying amount ΣY. Then, the process returns to step S518. In this manner, the accuracy of sheet edge detection can be appropriately controlled.

[0041] <End detection position> Here, the operation of detecting the edge of the sheet in the case where preliminary ejection is not performed on the B side will be described. FIG. 10 is a diagram for explaining the position of edge detection on the sheet. FIG. 11 is a diagram for explaining the edge position in the section of the transport amount Y1. The edges on both sides A and B are detected until the accumulated transport amount of the sheet reaches the transport amount Y1, and then the edge on the A side is detected without the edge on the B side being detected until the accumulated transport amount of the sheet reaches the transport amount Y2. Then, when the accumulated transport amount of the sheet reaches the transport amount Y2, the edge on the B side is detected.

[0042] The conveyance amount Y1 is a section in which edge detection is performed on both sides A and B from the start of recording (first control). The conveyance amount Y2 is a section in which edge detection is performed only on the A side until the target is reached (second control), and edge detection is performed on the B side when the target is reached (third control). Edge detection on the A side is performed during scanning in the return direction from the B side to the A side, and edge detection on the B side is performed during scanning in the forward direction from the A side to the B side. Therefore, the first scan (X1) detects the edge B1 on the B side, and the second scan (X2) detects the edge A2 on the A side. Similarly, the third scan (X3) detects the edge B3 on the B side, and the fourth scan (X4) detects the edge A4 on the A side. Note that the edge A1 is detected after the recording job is received and the sheet is conveyed to the recording position (S500 process).

[0043] Here, the edge detection operation will be described by taking as an example a case where a print job for an A4 sheet (210 mm x 297 mm) is received. In the section of the transport amount Y1, the edge detection of the B side is performed when scanning in the forward direction from the A side to the B side, and the edge detection of the A side is performed when scanning in the backward direction from the B side to the A side. Note that, as the section of the transport amount Y1 becomes larger, the number of detections of the edge of the B side increases, and the throughput of recording the image becomes slower. Conversely, as the section of the transport amount Y1 becomes smaller, the number of detections of the edge of the B side decreases, and the estimation accuracy of the sheet width deteriorates. In this embodiment, the section of the transport amount Y1 is set to 29.7 mm, which is one-tenth of the sheet length of 297 mm of an A4 sheet. Also, the description will be given assuming that the print overhang amount during borderless printing is 0.3 mm, the nozzle length of the print head 10 is 20 mm, and the four-time overwrite mode is used. Note that in the four-time overwrite mode, the sheet is transported by 1 / 4 the nozzle length to perform overwriting, so the reference transport amount of the sheet for each scan of the carriage is 5 mm. When the section of the conveyance amount Y1 is 29.7 mm and the standard conveyance amount of one sheet is 5 mm, the detection positions of the A side end in the section of the conveyance amount Y1 are A1, A2, A4, and A6. The detection positions of the B side end are B1, B3, B5, and B7. The detection results (distance from the X origin) are A1: 25.03 mm, A2: 25.05 mm, A4: 25.06 mm, A6: 25.07 mm, B1: 235.15 mm, B3: 235.19 mm, B5: 235.21 mm, and B7: 235.23 mm. The calculated value of the sheet width in the first scan is 210.12 mm, which is the position difference between the B side and the A side. Since the B side end detection is not performed in the second scan, the B side end position is calculated using the detection result of the first scan, 235.15 mm, and the calculated sheet width is 210.10 mm. Since edge detection for side A is not performed in the third scan, the edge position for side A is calculated using 25.05 mm from the second scan, and the calculated sheet width is 210.14 mm. After that, the sheet width for each scan is calculated using the detection result from the previous scan for the position on the side where the edge is not detected.

[0044] The calculated sheet width is the value shown in FIG. 11. The transport amount Y2 and the recording width after the transport amount Y1 are determined from the calculated sheet width values ​​in each scan in the transport amount Y1 section. The rightmost column in FIG. 11 shows the difference from the sheet width calculation result of one scan before. The maximum difference in FIG. 11 is 0.04 mm, and the cumulative maximum difference is set as the worst case, and a transport amount that does not exceed the recording overhang is set as Y2. This prevents the writing position from being inside the sheet and creating a blank space during borderless recording. In other words, if the maximum difference of 0.04 mm is continuously accumulated, the recording overhang amount of 0.3 mm will be exceeded in 8 scans. Therefore, 30 mm for 6 scans is set as the transport amount Y2. The reason why it is not set to 35 mm for 7 scans here is because the writing position during recording uses the detection result of one scan before. The recording width is set to 210.76 mm, which is the calculated maximum sheet width of 210.16 mm plus the recording overhang amount of 0.3 mm in the left and right directions.

[0045] From the 8th scan, in the section of the transport amount Y2, only the A-side edge detection is performed during the return scan from the B side to the A side. The B-side writing position from the 8th scan onwards can be determined from the A-side edge detection result and the recording width calculated from the detection result of the Y1 section. After further transporting the transport amount Y1, the B-side edge detection is performed in the 13th scan, which is equal to or greater than the transport amount set in the transport amount Y2, and the sheet width is recalculated from the A-side edge detection result in the 12th scan, which is one scan before, to determine the recording width from the 14th scan onwards. In this way, the CPU 301 alternately performs control to detect the A-side edge before the transport amount Y2 is reached and control to detect the B-side edge when the transport amount Y2 is reached, until the rear end of the sheet is reached.

[0046] Here, a predicted sheet width value assumed from the detection result of the section of the conveyance amount Y1 is expressed by Equation 1.

[0047] Formula 1 (Maximum sheet width calculation value) + (Number of scans reached Y2) × (Maximum sheet width difference) 11, the conveyance distance is 210.40 mm (210.16 mm+6 scans×0.04 mm). If the detection result of the sheet width in the 13th scan is close to the predicted sheet width, the conveyance distance Y2 from the 14th scan onwards may be reduced.

[0048] According to the above setting, the sheet width and the sheet width difference are calculated in the section where the transport amount is 1 / 10 of the sheet length from the start of recording, and the number of times the edge detection is performed on the B side in the section of the transport amount Y2 can be reduced. Therefore, the throughput can be improved without affecting the image. Note that the end position on the B side can be estimated by linearly approximating the end position from the result of the end position on the B side in the section of the transport amount Y1, and the transport amount Y2 can be obtained based on the standard deviation between the approximate position and the detection result. In this case, the end detection on the B side in the section of the transport amount Y1 must be performed at least three times. Note that when preliminary ejection is performed on the B side, the end detection on the B side is performed, and the sheet width is corrected in the same way as when the transport amount Y2 is reached. In this case, the next end detection on the B side is performed when the cumulative transport amount of the sheet reaches the transport amount Y2 from the execution of the preliminary ejection.

[0049] <Environmental condition correction method> As described above, the section of the transport amount Y1 where both ends are detected from the start of recording is set at the start of recording based on the sheet size and recording mode. The transport amount Y2 after the transport amount Y1 is set when the transport amount Y1 is reached and each time the transport amount Y2 is reached, based on the results of the detection of both ends in the section of the transport amount Y1. However, since the sheet deforms due to environmental conditions such as humidity, the transport amount Y2 where the edge detection on the B side is performed may be changed depending on the change in the surrounding environment during recording, by the time recording of an image on one sheet is completed. The process of FIG. 7 is a flowchart explaining a setting method that takes environmental conditions into consideration when setting the transport amount Y2.

[0050] In step S1001, the CPU 301 determines whether the difference between the calculation result of the sheet width and the sheet width prediction value based on the formula 1 is equal to or less than a predetermined amount. If the difference is equal to or less than the predetermined amount, the CPU 301 changes the value of the conveyance amount Y2 to Y2' (for example, 2 / 3 of Y2) in step S1002. That is, since it is close to the sheet width prediction value, it is necessary to reduce the overhang amount. On the other hand, if the difference exceeds the predetermined amount, the process proceeds to step S1003. In step S1003, the CPU 301 determines whether the surrounding environment is humid based on the values ​​of the temperature sensor 326 and the humidity sensor 327. If it is determined that the surrounding environment is not humid, the section for performing the edge detection on the B side is not changed. If it is determined that the surrounding environment is humid, the CPU 301 changes the interval for performing the edge detection on the B side to Y2' in step S1004. That is, the section for performing the edge detection on the B side is shortened. As a result, the overhang amount can be accurately reduced. In this way, by changing the transport amount Y2 in response to changes in the surrounding environment, the protrusion amount can be accurately reduced. [Explanation of symbols]

[0051] 10. Recording head 100 Recording device 103 Conveyor 105 Carriage 301 CPU 401 Detection Sensor

Claims

1. A conveying means for conveying the sheet in a conveying direction; a recording means for recording an image on the sheet conveyed by the conveying means by discharging a liquid; a carriage for moving the recording means in a width direction of the sheet intersecting the conveying direction; a detection unit mounted on the carriage and configured to detect a first end of the sheet in the width direction and a second end different from the first end; a control unit that executes a first control to cause the detection unit to detect the first end and the second end of the sheet until an accumulated conveyance amount of the sheet reaches a first conveyance amount; A recording device comprising: The control means executes a second control to detect the first end without detecting the second end until the accumulated transport amount of the sheet reaches the second transport amount after the accumulated transport amount of the sheet reaches the first transport amount, and executes a third control to detect the second end when the accumulated transport amount of the sheet reaches the second transport amount.

2. 2. The recording apparatus according to claim 1, wherein said control means causes said detection means to detect said first end before an image is recorded on a sheet.

3. 3. The recording apparatus according to claim 1, wherein the control means executes the first control when recording of an image on a sheet is started.

4. 4. The recording apparatus according to claim 1, wherein the control unit alternately executes the second control and the third control after the first control, until the trailing edge of the sheet is reached.

5. 5. The recording apparatus according to claim 1, wherein the accumulated conveyance amount of the sheet is reset to zero each time the first control or the third control ends.

6. 6. The recording apparatus according to claim 1, wherein the detection means is disposed on a side of the first end of the carriage in the width direction.

7. A recording device as described in any one of claims 1 to 6, characterized in that when performing the second control, a preliminary ejection is performed to eject liquid that does not contribute to an image, the control means terminates the second control, and when the recording means moves to a preliminary ejection position, the second end is detected by the detection means.

8. 8. The recording apparatus according to claim 1, wherein the first transport amount is changed depending on a size of the sheet.

9. 9. The recording apparatus according to claim 1, wherein the second transport amount is changed based on a reference transport amount for transporting the sheet every time the carriage makes one scan.

10. A recording apparatus according to any one of claims 1 to 9, characterized in that the second transport amount is calculated based on the position of the first end portion and the position of the second end portion of the sheet detected from the start of recording until the sheet is transported the first transport amount.

11. 11. The recording apparatus according to claim 10, wherein the second transport amount is calculated based on a difference between the position of the first end and the position of the second end and the number of scans of the carriage during the second transport amount.

12. 11. The recording apparatus according to claim 1, wherein the second transport amount is changed based on humidity or temperature.

Images