Printing apparatus, control method thereof, and storage medium

Abstract

The present application provides a printing device, a control method thereof, and a storage medium. The printing device includes a supply member configured to supply a print medium; an intermediate roller configured to convey the print medium; a conveyance roller configured to convey the print medium; a printing member configured to print an image on the print medium; a reverse path configured to return the print medium that has been reversed in a forward-reverse direction to the intermediate roller; and a control member capable of: first control for causing a second print medium supplied from the supply member to overlap a first print medium being printed by the printing member, and second control for causing a second print medium conveyed from the reverse path to overlap the first print medium being printed by the printing member.

Description

Technical Field

[0001] The present invention relates to a printing apparatus capable of performing double-sided printing by automatically flipping the printing medium from the first side to the second side. Background Technology

[0002] Japanese Patent Application Publication No. 2017-052614 discloses a printing apparatus that is sequentially controlled such that the leading edge of a subsequent printing medium in the transport direction overlaps with a preceding printing medium that has been reversed by a reversing member after the first side has been printed, wherein the subsequent printing medium is fed from the paper loading unit after the preceding printing medium.

[0003] However, the device described in Japanese Patent Application Publication No. 2017-052614 controls the printing media so that only a portion of the subsequent printing media overlaps with the preceding printing media when the printing media is fed from the paper loading unit. Therefore, a technical problem exists: the subsequent printing media cannot overlap with the preceding printing media continuously, thus requiring time before the printing media is fed to the printing area opposite the print head. Summary of the Invention

[0004] In view of the above problems, the present invention provides a printing device that can shorten the time required to feed printing media to the printing area opposite the print head.

[0005] According to a first aspect of the present invention, a printing apparatus is provided, comprising: a supply member configured to supply a printing medium; an intermediate roller configured to convey the printing medium supplied by the supply member; a conveying roller configured to convey the printing medium conveyed by the intermediate roller in a conveying direction; a printing member configured to print an image on the printing medium conveyed by the conveying roller downstream of the conveying roller; a reversing path configured to return the printing medium printed by the printing member and reversed to the intermediate roller; and a control member capable of: a first control for overlapping a second printing medium supplied from the supply member with a first printing medium being printed by the printing member between the intermediate roller and the conveying roller; and a second control for overlapping a second printing medium conveyed from the reversing path with the first printing medium being printed by the printing member between the intermediate roller and the conveying roller.

[0006] According to a second aspect of the present invention, a control method for controlling a printing apparatus is provided, the printing apparatus comprising: a supply member configured to supply printing media; an intermediate roller configured to convey the printing media supplied by the supply member; a conveyor roller configured to convey the printing media conveyed by the intermediate roller in a conveying direction; a printing member configured to print an image on the printing media conveyed by the conveyor roller downstream of the conveyor roller; and a reversing path configured to return the printing media printed by the printing member and reversed to the intermediate roller, and the control method comprising performing control capable of: a first control for overlapping a second printing medium supplied from the supply member with a first printing medium being printed by the printing member between the intermediate roller and the conveyor roller; and a second control for overlapping a second printing medium conveyed from the reversing path with the first printing medium being printed by the printing member between the intermediate roller and the conveyor roller.

[0007] According to a third aspect of the present invention, a non-transitory computer-readable storage medium is provided, which stores a program that causes a computer to execute the control method of the printing device described above.

[0008] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a cross-sectional view of the main components of a printing device according to an embodiment of the present invention.

[0010] Figure 2 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0011] Figure 3 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0012] Figure 4 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0013] Figure 5 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0014] Figure 6 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0015] Figure 7 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0016] Figure 8 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0017] Figure 9 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0018] Figure 10 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0019] Figure 11 This is a diagram illustrating overlapping continuous feed in a printing apparatus according to an embodiment of the present invention.

[0020] Figure 12 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0021] Figure 13 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0022] Figure 14 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0023] Figure 15 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0024] Figure 16 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0025] Figure 17 This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0026] Figure 18A and Figure 18B This is a flowchart illustrating an overlapping continuous feed operation according to one embodiment.

[0027] Figure 19 This is a block diagram illustrating a printing apparatus according to one embodiment.

[0028] Figure 20A and Figure 20B This is a diagram showing the configuration of the pickup rollers.

[0029] Figure 21 This diagram illustrates the operations used to overlap subsequent sheets with preceding sheets.

[0030] Figure 22 This diagram illustrates the operations used to overlap subsequent sheets with preceding sheets.

[0031] Figure 23This is a flowchart illustrating the skew correction operation of a subsequent sheet according to one embodiment.

[0032] Figure 24 This is a flowchart illustrating the operations used to calculate the leading edge position of subsequent slices.

[0033] Figure 25 This is a diagram showing the printing area of ​​the first side of a printing medium P according to one embodiment.

[0034] Figure 26 This is a diagram illustrating the printing determination state of the first side of a printing medium P according to one embodiment. Detailed Implementation

[0035] In the following, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Several features are described in the embodiments, but it is not a limitation requiring all such features, and multiple such features can be suitably combined. Furthermore, in the drawings, the same reference numerals are given to the same or similar configurations, and redundant descriptions thereof are omitted.

[0036] Figure 1 This is a cross-sectional view showing the main components of a printing apparatus 200 according to an embodiment of the present invention. (The text will be used...) Figure 1 The overall configuration of the printing device 200 according to this embodiment is described in the accompanying drawings, STA to STC.

[0037] exist Figure 1 In the STA, P indicates the printing medium. Multiple sheets of printing media P are loaded in the paper loading unit 11. 2 indicates the pickup roller that contacts the topmost printing medium P loaded in the paper loading unit 11 to pick it up. 3 indicates the feed roller for feeding the printing medium P picked up by the pickup roller 2 downstream in the conveying direction along the first conveying path 100. 4 indicates the feed driven roller that applies force to the feed roller 3 and feeds the printing medium P by clamping it together with the feed roller 3. Note that the portion of the first conveying path 100 that guides the printing medium P between the feed roller 3 and the conveying roller 5 (described below) will be referred to as the "guide section 100a".

[0038] 5 indicates the transfer roller used to transfer the printing medium P fed by the feed roller 3 and the feed driven roller 4 to a position opposite the print head 7. 6 indicates the clamping roller that applies force to the transfer roller 5 and transfers the printing medium P by clamping it together with the transfer roller 5.

[0039] 7 indicates a printhead for printing on the printing medium P conveyed by the conveyor roller 5 and the clamping roller 6. In this embodiment, printhead 7 is described as an inkjet printhead that prints on the printing medium P by ejecting ink. 8 indicates a platform that supports the second side (back side) of the printing medium P at a position opposite to printhead 7. 1 indicates a carriage on which printhead 7 is mounted and which moves in a direction intersecting the printing medium conveying direction.

[0040] 9 indicates the reverse roller, which is capable of being driven by a second feed motor 207 (see...) Figure 19 )exist Figure 1 The STA rotates in the direction of arrow A (forward rotation) and is able to convey the print media P printed by printhead 7 in the direction of arrow C. The reverse roller 9 can discharge the print media P out of the device as shown by arrow C. Note that the portion used to guide the print media P from the discharge roller 10 (described below) to the downstream side of the reverse roller 9 in the conveying direction will be referred to as "discharge path 102".

[0041] Additionally, such as Figure 1 As shown in STB, in Figure 1 After the printing medium P is conveyed in the direction of arrow C in the STB, the second feed motor 207 is driven in reverse, and the printing medium P reaches the vicinity of the reverse roller 9 at the upstream end in the conveying direction. As a result, the reverse roller 9... Figure 1 The STC rotates in the direction of arrow B (rotates in the opposite direction), and the printing medium P flips over and is conveyed along the guide in the direction of arrow D in the figure within the second conveying path (reverse path) 101.

[0042] At this time, the reverse rotation of the reverse roller 9 also causes the intermediate roller 15 to... Figure 1 Rotating in the direction of arrow B in the STC (reverse direction) will move the printing medium P in the second conveying path 101 toward the feed roller 3.

[0043] 10 indicates the discharge roller that conveys the print medium P printed by the print head 7 in the direction of the reversing roller 9. 12 indicates a ratchet spur that rotates in contact with the print surface of the print medium P printed by the print head 7. Here, the ratchet 12 is forced toward the discharge roller 10. 13 indicates a reversing driven roller that is forced toward the reversing roller 9 and conveys the print medium P by clamping it together with the reversing roller 9. 14 indicates an intermediate driven roller that is forced toward the intermediate roller 15 and conveys the print medium P by clamping it together with the intermediate roller 15.

[0044] Between the feed roller gap formed by the feed roller 3 and the feed driven roller 4 and the transfer roller gap formed by the transfer roller 5 and the clamping roller 6, the printing medium P is guided by a guide within the first transfer path 100. A printing medium sensor 16 indicates the front and rear ends of the printing medium P. The printing medium sensor 16 is positioned downstream of the feed roller 3 in the printing medium transport direction.

[0045] Figure 20A and Figure 20B This diagram illustrates the configuration of the pickup roller 2. As described above, the pickup roller 2 contacts the topmost printing medium loaded in the paper loading unit 11 to pick up the printing medium. 19 indicates the drive shaft for transmitting driving force from the first feed motor 206 to the pickup roller 2. When picking up the printing medium P, the drive shaft 19 and the pickup roller 2... Figure 1 Rotate in the direction of arrow E in STA.

[0046] The drive shaft 19 is provided with a protrusion 19a. A recess 2c is formed on the pick-up roller 2 to engage the protrusion 19a. For example... Figure 20A As shown, when the protrusion 19a contacts the first surface 2a of the recess 2c in the pickup roller 2, the driving force of the drive shaft 19 is transmitted to the pickup roller 2, thus the pickup roller 2 rotates when the drive shaft 19 is driven. On the other hand, as Figure 20B As shown, when the protrusion 19a contacts the second surface 2b of the recess 2c in the pickup roller 2, the driving force of the drive shaft 19 is not transmitted to the pickup roller 2, so the pickup roller 2 does not rotate even if the drive shaft 19 is driven. Additionally, when the protrusion 19a is neither in contact with the first surface 2a nor the second surface 2b, and is between the first surface 2a and the second surface 2b, the pickup roller 2 also does not rotate even if the drive shaft 19 is driven.

[0047] Figure 19 This is a block diagram illustrating a printing apparatus 200 according to this embodiment. 201 indicates an MPU for controlling the operation and data processing of various units, etc. As will be described later, the MPU 201 serves as a transport control unit capable of controlling the transport of the printing media such that the rear end of the preceding printing media and the front end of the subsequent printing media overlap. 202 indicates a ROM for storing programs and data executed by the MPU 201, etc. 203 indicates a RAM for temporarily storing data processed by the MPU 201 and data received from the host computer 214, etc.

[0048] The printhead 7 is controlled by the printhead driver 212. The carriage motor 204, which drives the carriage 1, is controlled by the carriage motor driver 208. The conveyor roller 5 and the discharge roller 10 are driven by the conveyor motor 205. The conveyor motor 205 is controlled by the conveyor motor driver 209.

[0049] Pick-up roller 2, feed roller 3, and intermediate roller 15 are driven by a first feed motor 206. The first feed motor 206 is controlled by a first feed motor driver 210. Reversing roller 9 and intermediate roller 15 are driven by a second feed motor 207.

[0050] At this time, the pickup roller 2 and the feed roller 3 rotate synchronously in response to the forward drive of the first feed motor 206, and convey the printing medium P in the direction of the transfer roller 5. During the reverse drive of the first feed motor 206, the following operations are performed as a result of a drive switch (not shown). During the reverse drive in the first drive switch state, only the feed roller 3 rotates, and the printing medium P is conveyed in the direction of the transfer roller 5. Then, during the reverse drive in the second drive switch state, both the feed roller 3 and the intermediate roller 15 rotate, and the printing medium P is conveyed in the direction of the transfer roller 5.

[0051] As a result of the forward drive of the second feed motor 207, the reverse roller 9 rotates in the direction for discharging the printing medium P out of the device. On the other hand, in the reverse drive of the second feed motor 207, the reverse roller 9 and the intermediate roller 15 rotate synchronously and convey the printing medium P in the second transport path 101 in the direction of the feed roller 3.

[0052] The host computer 214 is equipped with a printer driver 2141, which is used to compile printing information such as the printed image and the printed image quality when the user instructs to perform a printing operation, and communicate the printing information to the printing device 200. The MPU 201 exchanges printed images with the host computer 214 via the I / F unit 213.

[0053] Reference Figure 2 ST1 to Figure 11 ST29 in the example describes the operation of overlapping continuous feed during duplex printing mode in chronological order, using the example of printing six pages of print data on both sides of three print media P in a single job. When the print data for duplex printing mode is sent from the host computer 214 via I / F unit 213, the print data is processed by MPU 201 and then expanded in RAM 203. The printing operation is then started based on the data expanded by MPU 201.

[0054] Reference Figure 2ST1 in the description is as follows. First, the first feed motor 206 is driven at a low speed by the first feed motor driver 210 to rotate in the forward direction. As a result, the pickup roller 2 rotates at 7.6 inches per second. As the pickup roller 2 rotates, the topmost print media P loaded in the paper loading unit 11 is picked up. The first print media P picked up by the pickup roller 2 is conveyed by the feed roller 3, which rotates in the same direction as the pickup roller 2, while being guided by the guide 100a. The feed roller 3 is also driven by the first feed motor 206. This embodiment describes a configuration including the pickup roller 2 and the feed roller 3. However, this configuration may be such that only the feed roller 3 for feeding the print media loaded in the paper loading unit 11 is included.

[0055] When the print media sensor 16, located downstream of the feed roller 3 in the conveying direction, senses the leading edge of the first print media P, the first feed motor 206 switches to high-speed drive while continuing forward drive. In other words, the pickup roller 2 and the feed roller 3 rotate at 20 inches per second.

[0056] Now refer to Figure 2 ST2 in the diagram describes this process. As the feed roller 3 continues to rotate, the leading edge of the first print media P on the downstream side in the conveying direction contacts the conveyor roller gap formed by the conveyor roller 5 and the clamping roller 6. At this point, the conveyor roller 5 stops. Even after the leading edge of the first print media P contacts the conveyor roller gap on the downstream side in the conveying direction, the feed roller 3 rotates a predetermined amount, and as a result, the leading edge of the first print media P is aligned while in contact with the conveyor roller gap, thus correcting skew. These skew correction operations are also referred to as "registration operations".

[0057] Now refer to Figure 2 ST3 in the document provides a description. Once the skew correction operation of the first print media P is completed, the conveyor roller 5 begins to rotate as a result of being driven by the conveyor motor 205. The conveyor roller 5 conveys the print media at 15 inches per second. After aligning the first print media P with the position opposite the print head 7, the print head 7 ejects ink based on the print data of the first page, which begins the printing operation on the first side of the first print media P.

[0058] Here, as Figure 25 As shown, the length of the printing medium P in the transport direction is represented by L. When printing onto the first printed surface of the printing medium P, the print density of the region S ((1 / 4)L portion) at the leading end in the transport direction at the current stage indicated by arrow A is compared with the preset print density. If, as a result of the comparison, the print density of the region S is within the preset print density, S(1) = 0 is stored in RAM 203; otherwise, S(1) = 1 is stored. The numbers in parentheses indicate the number of sheets printed.

[0059] Additionally, while printing on the first print media P is in progress, the print density of region K ((1 / 4)L portion) at the rear end in the transport direction, as indicated by arrow A, is compared with a preset print density. If, as a result of the comparison, the print density of region K is within the preset print density, K(1) = 0 is stored in RAM 203; otherwise, K(1) = 1 is stored. The number in parentheses also indicates the number of sheets printed here.

[0060] Additionally, such as Figure 26 As shown, when the number of prints N of the printing medium P becomes at least four, the value of N in S(N) and K(N) is converted to the value of M in the table, and overwritten in the storage areas of S(M) and K(M) as needed.

[0061] Note that the alignment operation is performed by first positioning the leading edge of the first print media P at the position of the conveyor roller 5 by contacting the leading edge of the conveyor roller with the gap between the conveyor rollers, and then controlling the rotation amount of the conveyor roller 5 using the position of the conveyor roller 5 as a reference. When the second print media P needs to be picked up from the paper loading unit using the pickup roller 2 during the alignment operation, the first feed motor 206 is driven in the forward direction, and the pickup roller 2 and the feed roller 3 are also driven synchronously with the conveyor roller 5.

[0062] When it is not necessary to pick up the second printing medium P, the first feed motor 206 is reverse-driven in the first drive switch state, and the feed roller 3 is driven synchronously with the transfer roller 5 only.

[0063] In this embodiment, when there is print data to be printed on a second print medium P and a subsequent print medium P, the print medium P to be printed after the printing operation on the first surface of the first print medium P is the second print medium P picked up from the paper loading unit 11. Then, its first surface is set to be printed after the first surface of the first print medium P. Therefore, the second print medium P needs to be picked up (delayed feed) after a predetermined length of time has passed the pick-up roller 2 and the drive shaft 19 has been driven at the upstream end (rear end) of the first print medium P in the conveying direction. Therefore, the first feed motor 206 is driven in the forward direction.

[0064] The printing device in this embodiment is a serial printing device in which the printhead 7 is mounted on the carriage 1. Repeated transport and image forming operations are performed. In the transport operation, the transport roller 5 intermittently transports a predetermined amount of printing media each time. In the image forming operation, with the transport roller 5 stopped, ink is ejected from the printhead 7 while the carriage 1 on which the printhead 7 is mounted is moved. As a result of these operations, a printing operation is performed on the first printing medium P.

[0065] Once the first print media P is aligned, the forward drive of the first feed motor 206 is switched to a low-speed drive. In other words, the pickup roller 2 and the feed roller 3 rotate at 7.6 inches per second. As the conveyor roller 5 intermittently conveys the first print media P in a predetermined amount each time, the feed roller 3 is also intermittently driven by the first feed motor 206. In other words, when the conveyor roller 5 rotates, the feed roller 3 also rotates, and when the conveyor roller 5 stops, the feed roller 3 also stops. The rotational speed of the feed roller 3 is lower than the rotational speed (conveyor speed) of the conveyor roller 5. Therefore, the print media P becomes taut between the conveyor roller 5 and the feed roller 3. In other words, the feed roller 3 is rotated by the first print media P conveyed by the conveyor roller 5.

[0066] The first feed motor 206 is intermittently driven in the forward direction, and thus the drive shaft 19 is also driven. As previously mentioned, the rotational speed of the pickup roller 2 is lower than that of the transfer roller 5. Accordingly, the pickup roller 2 rotates by the print media P conveyed by the transfer roller 5. In other words, the pickup roller 2 moves ahead of the drive shaft 19. Specifically, the protrusion 19a of the drive shaft 19 separates from the first surface 2a and contacts the second surface 2b. Therefore, even if the first print media P passes the pickup roller 2 at its upstream end (rear end) in the conveying direction, the second print media P will not be picked up immediately. When the drive shaft 19 has been driven for a predetermined length of time, the protrusion 19a contacts the first surface 2a, and the pickup roller 2 begins to rotate.

[0067] Due to factors such as sensor responsiveness, the print media sensor 16 requires a predetermined interval between print media in order to sense the ends of the print media P. In other words, a predetermined time interval needs to be provided between when the print media sensor 16 senses the upstream end (rear end) of the first print media P in the transport direction and when the print media sensor 16 senses the downstream front end of the second print media P in the transport direction. Accordingly, the upstream end of the first print media P in the transport direction and the downstream front end of the second print media P in the transport direction need to be separated by a predetermined distance, and the recess 2c of the pick-up roller 2 is set to approximately 70 degrees.

[0068] Now refer to Figure 3 ST4 in the diagram describes the process. The second print media P picked up by pickup roller 2 is conveyed by feed roller 3. At this time, printhead 7 is performing image forming operations on the first print media P based on print data. When print media sensor 16 senses the leading edge of the second print media P, the first feed motor 206 switches to high-speed drive while continuing forward drive. In other words, pickup roller 2 and feed roller 3 rotate at 20 inches per second.

[0069] Now refer to Figure 3ST5 in the document describes this. Compared to the speed at which the first print medium P moves downstream as a result of the printing operation of the print head 7, the second print medium P is moved at a higher speed, which makes it possible to produce a state in which the downstream front end of the second print medium P in the conveying direction overlaps with the upstream end of the first print medium P in the conveying direction.

[0070] Printing is performed based on the print data of the first print media P, and the first print media P is thus intermittently conveyed by the conveyor roller 5. Meanwhile, after the print media sensor 16 senses the downstream leading edge of the second print media P in the conveying direction, the feed roller 3 rotates continuously at 20 inches per second, allowing the second print media P to catch up with the first print media P. The second print media P is then conveyed via the feed roller 3 until its downstream leading edge in the conveying direction stops at a predetermined position upstream of the conveyor roller gap. The position of the downstream leading edge of the second print media P in the conveying direction is calculated based on the amount of rotation of the feed roller 3 after the print media sensor 16 senses its downstream leading edge, and the position of the downstream leading edge of the second print media P in the conveying direction is controlled based on this calculation. At this time, the print head 7 is performing an image forming operation on the first print media P based on the print data.

[0071] Now refer to Figure 3 ST6 in the document describes the process. When the transport roller 5 is stopped to perform an image forming operation (ink jetting operation) on the final line of the first print media P, a skew correction operation for the second print media P is performed by driving the feed roller 3 so that the leading edge of the second print media P contacts the gap of the transport roller.

[0072] Now refer to Figure 4 ST7 in the document provides a description. When the image forming operation of the final line of the first print medium P is completed, the second print medium P can be aligned by rotating the transfer roller 5 by a predetermined amount and keeping the second print medium P overlapping the first print medium P.

[0073] After the pickup roller 2 feeds the second print medium P from the paper loading unit 11, it is determined whether the print medium P to be aligned has already been fed from the paper loading unit 11. When it is determined that the print medium P to be aligned has been fed from the paper loading unit 11, the next print medium P following that print medium P is selected and fed from the second transport path 101 to the position opposite to the print head 7. In this determination, it is determined that the second print medium P has been fed from the paper loading unit 11, therefore the next print medium P following the second print medium P to be aligned is fed from the second transport path 101 to the position opposite to the print head 7. It is also necessary to ensure that the next print medium P following the second print medium P to be aligned is not fed with a delay from the paper loading unit 11. Furthermore, since the second print medium P is being fed from the paper loading unit 11, the alignment of the second print medium P is performed by reversing the first feed motor 206 in the first drive switch state. Control is performed so that the feed roller 3 is driven together with the transport roller 5 without transmitting driving force to the pickup roller 2 and the intermediate roller 15.

[0074] Once the second print media P is aligned, the first feed motor 206 switches to low-speed drive while continuing its reverse drive in the first drive switch state. In other words, the feed roller 3 rotates at 7.6 inches per second. The feed roller 3 is also intermittently driven by the first feed motor 206 as the conveyor roller 5 intermittently conveys the second print media P in predetermined amounts each time. The printhead 7 performs the printing operation on the second print media P based on the printing data.

[0075] At this time, similar to the printing on the first surface of the first printing medium P, the printing density is compared, wherein if the printing density of region S falls within the preset printing density, S(2) = 0 is stored in RAM 203, and if not, S(2) = 1 is stored. Additionally, when the printing operation on the second printing medium P is in progress, the printing density of region K ((1 / 4)L portion) at the rear end of the second printing medium in the transport direction at the current stage is compared with the preset printing density (see [reference]). Figure 25 If, as a result of the comparison, the print density of region K is within the preset print density, then K(2) = 0 is stored in RAM203; otherwise, K(2) = 1 is stored. The first print medium P is also intermittently transmitted while the second print medium P is being transmitted for printing operations.

[0076] Now refer to Figure 4 ST8 in the document provides a description. After determining that the upstream end of the first printing medium P has passed the ratchet 12 in the conveying direction based on the amount of rotation of the conveyor roller 5 from the start of the alignment operation and the length of the sheet, the second feed motor driver 211 causes the second feed motor 207 to rotate at high speed in the forward direction. The reverse roller 9... Figure 1 The first print media P rotates at 18 inches per second in the direction of arrow A. As a result, the reversing roller 9 conveys the first print media P faster than the conveying roller 5 conveys the second print media P. The upstream end of the first print media P in the conveying direction and the downstream front end of the second print media P in the conveying direction no longer overlap. Then, as will be described later, the first print media P, after being reversed by the reversing roller 9, enters the second conveying path 101, and the upstream rear end of the first print media P in the conveying direction passes through the reversing roller 9, while the downstream front end of the second print media P in the conveying direction is able to pass through the reversing roller 9. "The upstream rear end of the first print media P within the second conveying path 101" means the downstream front end in the first conveying path 100 before reversal.

[0077] Now refer to Figure 4 ST9 is described in the text. When the reverse roller 9 is in Figure 1 When rotating in the direction of arrow A in STA, in Figure 1 The first printing medium P is conveyed in the direction of arrow C in the STA. As a result, the first printing medium P is continuously conveyed until its upstream end in the conveying direction reaches the predetermined position of the reverse roller 9 upstream in the conveying direction. Therefore, the upstream end of the first printing medium P in the conveying direction and the downstream front end of the second printing medium P, which is being conveyed intermittently in a predetermined amount, are pulled apart.

[0078] Now refer to Figure 5 ST10 in the document describes that when the first printing medium P reaches the predetermined position on the upstream side of the reverse roller 9 in the conveying direction, the second feed motor driver 211 drives the second feed motor 207 in reverse at high speed. As a result, the reverse roller 9 and the intermediate roller 15... Figure 1 The STC rotates at 18 inches per second in the direction of arrow B. Then, the reverse roller 9 and the intermediate roller 15 convey the first printing medium P along the guide within the second conveying path (reverse path) 101 until its downstream leading edge in the conveying direction reaches a predetermined position before the first conveying path 100. This predetermined position is also calculated based on the amount of rotation of the conveying roller 5 since the start of the alignment operation and the length of the sheet.

[0079] Now refer to Figure 5 ST11 in the document describes this process. When the second printing medium P is being conveyed and the printing medium sensor 16 senses the upstream end of the second printing medium P in the conveying direction, the first feed motor driver 210 reverses the first feed motor 206 at low speed in the second drive switch state. As a result, the intermediate roller 15 and the feed roller 3... Figure 1The STC rotates at 7.6 inches per second in the direction of arrow B. Then, the intermediate roller 15 and feed roller 3 transport the first print media P from the second transport path 101 to the first transport path 100 in the direction of the transport roller 5. At this time, the printhead 7 is performing an image forming operation on the second print media P based on the print data. When the print media sensor 16 senses the downstream leading edge of the first print media P in the transport direction, the first feed motor 206 switches to high-speed drive while continuing the reverse drive in the second drive switch state. In other words, the intermediate roller 15 and feed roller 3 rotate at 20 inches per second.

[0080] Before the first feed motor 206 switches to high-speed drive, the aforementioned values ​​of the downstream end of the first print medium P in the transport direction and the upstream end of the second print medium P in the transport direction stored in RAM 203 are checked. "Downstream end of the first print medium P within the second transport path 101" means the upstream end in the first transport path 100 before reversal. In other words, the value of K(1) stored in RAM 203 when printing on the rear end of the first surface of the first print medium P and the value of K(2) of the K region of the second print medium P are checked. If both K(1) and K(2) are 0, the first feed motor 206 switches to high-speed drive. If K(1) or K(2) is 1, the preceding and subsequent print media may not overlap due to the curling of the print medium P, so the first feed motor 206 does not switch to high-speed drive.

[0081] At this stage, the value of K(2) in region K of the second printing medium P is initially 0 because image data has not yet been printed. Therefore, when the value of K(1) is 1, the first feed motor 206 is not switched to high-speed drive, and the downstream front end of the first printing medium P in the conveying direction does not overlap with the upstream end of the second printing medium P in the conveying direction. The explanation will continue with the case where the value of K(1) is 0 and the first feed motor 206 is switched to high-speed drive.

[0082] Compared to the downstream speed of the second printing medium P as a result of the printing operation of printhead 7, the first printing medium P moves at a higher speed, which allows the front end of the first printing medium P to overlap with the rear end of the second printing medium P. The printing operation is performed based on the printing data of the second printing medium P, and therefore the second printing medium P is intermittently conveyed by the conveyor roller 5. On the other hand, after the printing medium sensor 16 senses the front end of the first printing medium P, the feed roller 3 and the intermediate roller 15 rotate continuously at 20 inches / second, which allows the first printing medium P to catch up with the second printing medium P.

[0083] Then, the first print media P is conveyed via the feed roller 3 until its downstream leading edge in the conveying direction stops at a predetermined position upstream of the conveying roller gap. The position of the downstream leading edge of the first print media P in the conveying direction is calculated based on the amount of rotation of the feed roller 3 after the print media sensor 16 senses the downstream leading edge of the first print media P in the conveying direction, and the position of the downstream leading edge of the first print media P in the conveying direction is controlled based on this calculation result. Meanwhile, the print head 7 is performing an image forming operation on the second print media P based on the print data.

[0084] Now refer to Figure 5 ST12 in the document describes the process. When the conveyor roller 5 is stopped to perform an image forming operation (ink jetting operation) on the final line of the second printing medium P, a skew correction operation for the first printing medium P is performed by driving the feed roller 3 so that the leading edge of the first printing medium P on the downstream side in the conveying direction contacts the gap of the conveyor roller.

[0085] Now refer to Figure 6 ST13 in the document provides a description. When the image forming operation for the final line of the second print media P is completed, the first print media P can be aligned by rotating the transfer roller 5 by a predetermined amount and keeping the first print media P overlapping the second print media P.

[0086] As previously described, after the pickup roller 2 feeds the second print medium P from the paper loading unit 11, it is determined whether the print medium P to be aligned has already been fed from the paper loading unit 11. When it is determined that the print medium P has been fed from the second transport path 101, it is further determined whether the print data on the second side of the print medium P that was printing immediately before the alignment is the final print data in a job. When it is determined that the print medium P to be aligned has been fed from the second transport path 101, and the print data on the second side of the print medium P that was printing immediately before the alignment is the final print data in a job, the following control is performed. That is, the next print medium P after the selected print medium P is fed from the second transport path to a position opposite to the print head 7.

[0087] Additionally, if it is determined that a print medium P to be aligned has been fed from the second transport path 101, and the print data on the second side of the print medium P that is currently being printed is not the final print data in a job, the following control is performed. That is, the next print medium P after the selected print medium P is fed from the paper loading unit 11 to the position opposite to the print head 7.

[0088] In this determination, it is determined that the first print medium P is fed from the second transport path 101, and the print data on the second side of the second print medium P is not the final print data in a job. Accordingly, the next print medium P after the first print medium P to be aligned is fed from the paper loading unit 11 to a position opposite to the print head 7. It is also necessary to ensure that the next print medium P after the first print medium P to be aligned is fed from the paper loading unit 11 without delay. Furthermore, the first print medium P is being fed from the second transport path 101. Therefore, the alignment of the first print medium P is performed by reversing the first feed motor 206 in the second drive switch state, and by driving the feed roller 3 and the intermediate roller 15 together with the transport roller 5 without driving the pickup roller 2.

[0089] The intermediate roller 15 and the intermediate driven roller 14 are arranged in such a positional relationship that, as a result of aligning the first printing medium P, the upstream end of the first printing medium P in the conveying direction passes through the roll gap at the intermediate roller 15.

[0090] Next, the first feed motor 206 begins low-speed forward drive in the first drive switch state. In other words, the pickup roller 2 and the feed roller 3 rotate at 7.6 inches per second. As the conveyor roller 5 intermittently conveys the first print media P in a predetermined amount each time, the pickup roller 2 and the feed roller 3 are also intermittently driven by the first feed motor 206. The printhead 7 performs the printing operation on the first print media P based on the printing data. While the first print media P is intermittently conveyed for printing, the third print media P picked up by the pickup roller 2 from the paper loading unit 11 is also intermittently conveyed.

[0091] Now refer to Figure 6 ST14 in the document provides a description. After determining that the upstream end of the second printing medium P in the conveying direction has passed the ratchet 12 based on the amount of rotation of the conveying roller 5 from the start of the alignment operation and the length of the sheet, the second feed motor driver 211 causes the second feed motor 207 to rotate at high speed in the forward direction. The reverse roller 9... Figure 1 The reverse roller 9 rotates at 18 inches per second in the direction of arrow A. As a result, the reverse roller 9 conveys the second print media P faster than the conveyor roller 5 conveys the first print media P. The upstream end of the second print media P in the conveying direction and the downstream front end of the first print media P in the conveying direction no longer overlap. Then, after being reversed by the reverse roller 9, the second print media P enters the second conveying path 101, and the upstream rear end of the second print media P in the conveying direction passes through the reverse roller 9, while the downstream front end of the first print media P in the conveying direction can pass through the reverse roller 9. "The upstream rear end of the second print media P in the second conveying path 101" means the downstream front end in the first conveying path 100 before reversal.

[0092] Now refer to Figure 6 ST15 in the document provides a description. When the reverse roller 9 is in Figure 1 When rotating in the direction of arrow A in STA, in Figure 1 The second printing medium P is conveyed in the direction of arrow C in the STA. As a result, the second printing medium P is continuously conveyed until its upstream end in the conveying direction reaches the predetermined position of the reverse roller 9 upstream in the conveying direction. Therefore, the upstream end of the second printing medium P in the conveying direction and the downstream front end of the first printing medium P, which is being conveyed intermittently in a predetermined amount, are pulled apart.

[0093] When the second printing medium P reaches the predetermined position on the upstream side of the reverse roller 9 in the conveying direction, the second feed motor driver 211 drives the second feed motor 207 in reverse at high speed. As a result, the reverse roller 9 and the intermediate roller 15... Figure 1 The STC rotates at 18 inches per second in the direction of arrow B. Then, the reverse roller 9 and the intermediate roller 15 convey the second printing medium P along the guide within the second conveying path (reverse path) 101 until its downstream leading edge in the conveying direction reaches a predetermined position before the first conveying path 100. This predetermined position is also calculated based on the amount of rotation of the conveying roller 5 since the start of the alignment operation and the length of the sheet.

[0094] Now refer to Figure 7 ST16 in the document describes the process. The third print media P, picked up from the paper loading unit 11 by the pickup roller 2, is conveyed by the feed roller 3. At this time, the print head 7 is performing an image forming operation on the first print media P based on the print data. When the print media sensor 16 senses the leading edge of the third print media P, the first feed motor 206 switches to high-speed drive while continuing forward drive. In other words, the pickup roller 2 and the feed roller 3 rotate at 20 inches per second.

[0095] At this time, similar to the operation described above, before the first feed motor 206 switches to high-speed drive, the values ​​of the upstream end of the preceding printing medium P in the transport direction and the downstream front end of the subsequent printing medium P in the transport direction stored in RAM 203 are checked. In other words, the value of S(1) stored in RAM 203 when printing on the front end of the first surface of the first printing medium P and the value of S(3) of the S region of the third printing medium P are checked. Note that when the S region of the front end of the first surface of the first printing medium P is reversed and fed to the printing position through the second transport path 101, it becomes the upstream end (rear end) of the first printing medium P in the transport direction. If both S(1) and S(3) are zero, the first feed motor 206 switches to high-speed drive. If S(1) or S(3) is 1, the preceding and subsequent printing media may not overlap due to the curling of the printing medium P, so the first feed motor 206 does not switch to high-speed drive. At this stage, the value of S(3) in region S of the third printing medium P is initially 0 because no image data has been printed yet. When the value of S(1) is 1, the first feed motor 206 does not switch to high-speed drive, and the downstream front end of the third printing medium P in the conveying direction does not overlap with the upstream end of the first printing medium P in the conveying direction. The explanation will continue with the case where the value of S(1) is 0 and the first feed motor 206 switches to high-speed drive.

[0096] Now refer to Figure 7 ST17 in the document describes this process. The third printing medium P moves at a higher speed than the first printing medium P, which is the result of the printing operation of printhead 7. This allows the leading edge of the third printing medium P to overlap with the trailing edge of the first printing medium P. The printing operation is performed based on the printing data of the first printing medium P, and thus the first printing medium P is intermittently conveyed by the conveyor roller 5. On the other hand, after the printing medium sensor 16 senses the leading edge of the third printing medium P, the feed roller 3 rotates continuously at 20 inches per second, allowing the third printing medium P to catch up with the first printing medium P. The third printing medium P is then conveyed via the feed roller 3 until the leading edge of the third printing medium P on the downstream side in the conveying direction stops at a predetermined position upstream of the conveyor roller gap. The position of the leading edge of the third printing medium P on the downstream side in the conveying direction is calculated based on the amount of rotation of the feed roller 3 after the printing medium sensor 16 senses the leading edge of the third printing medium P on the downstream side in the conveying direction, and the position of the leading edge of the third printing medium P on the downstream side in the conveying direction is controlled based on the result of this calculation. At this time, printhead 7 is performing an image forming operation on the first print medium P based on the print data.

[0097] Now refer to Figure 7 ST18 in the document describes the process. When the transport roller 5 is stopped to perform an image forming operation (ink jetting operation) on the final line of the first print media P, a skew correction operation for the third print media P is performed by driving the feed roller 3 so that the leading edge of the third print media P contacts the gap of the transport roller.

[0098] Now refer to Figure 8 ST19 in the document provides a description. When the image forming operation of the final line of the first print medium P is completed, the third print medium P can be aligned by rotating the transfer roller 5 by a predetermined amount and keeping the third print medium P overlapping the first print medium P.

[0099] As previously described, after the pickup roller 2 feeds the second print medium P from the paper loading unit 11, it is determined whether the print medium P to be aligned has been fed from the paper loading unit 11. When it is determined that the print medium P has been fed from the paper loading unit 11, the next print medium P after the print medium P to be aligned is selected and fed from the second transport path 101 to the position opposite to the print head 7. In this determination, it is determined that the third print medium P has been fed from the paper loading unit 11, so the next print medium P after the third print medium P to be aligned is fed from the second transport path 101 to the position opposite to the print head 7. It is also necessary to ensure that the next print medium P after the third print medium P to be aligned is not fed from the paper loading unit 11 with a delay. Furthermore, the third print medium P is being fed from the paper loading unit 11. Therefore, during the alignment of the third print medium P, control is performed such that the first feed motor 206 is driven in reverse in the first drive switch state, and the feed roller 3 is driven together with the transport roller 5 without transmitting driving force to the pickup roller 2 and the intermediate roller 15.

[0100] Once the third print media P is aligned, the first feed motor 206 switches to low-speed drive while continuing reverse drive in the first drive switch state. In other words, the feed roller 3 rotates at 7.6 inches / second. The feed roller 3 is also intermittently driven by the first feed motor 206 as the conveyor roller 5 intermittently conveys the third print media P in a predetermined amount each time. The print head 7 performs a printing operation on the third print media P based on the printing data. At this time, similar to the printing on the first surface of the second print media P, the print density is compared, wherein if the print density of region S falls within the preset print density, S(3) = 0 is stored in RAM 203, and if not, S(3) = 1 is stored. Additionally, while the printing operation on the third print media P is in progress, the print density of region K ((1 / 4)L portion) at the rear end of the third print media in the conveying direction at the current stage is compared with the preset print density. If, as a result of the comparison, the print density of region K is within the preset print density, then K(3) = 0 is stored in RAM 203; otherwise, K(3) = 1 is stored. The first print medium P is also intermittently transmitted while the third print medium P is being used for the printing operation.

[0101] Now refer to Figure 8 ST20 is described in the text. After determining that the upstream end of the first printing medium P has passed the ratchet 12 in the conveying direction based on the amount of rotation of the conveyor roller 5 from the start of the alignment operation and the length of the sheet, the second feed motor driver 211 causes the second feed motor 207 to rotate at high speed in the forward direction. The reverse roller 9... Figure 1 The reverse roller 9 rotates at 18 inches per second in the direction of arrow A. As a result, the reverse roller 9 conveys the first print media P faster than the conveyor roller 5 conveys the third print media P. The upstream end of the first print media P and the downstream front end of the third print media P in the conveying direction no longer overlap.

[0102] Now refer to Figure 8 ST21 in the document provides a description. When the reverse roller 9 is in Figure 1 When rotating in the direction of arrow A in STA, in Figure 1 The first printing medium P is conveyed in the direction of arrow C in the STA. Printing of the first and second sides of the first printing medium P is completed. Then, the reverse roller 9... Figure 1 The STA rotates at 18 inches per second in the direction of arrow A, expelling the first print media P to the outside of the device. Additionally, the upstream end of the first print media P in the conveying direction and the downstream front end of the third print media P, which is being conveyed intermittently in a predetermined amount, are pulled apart.

[0103] Now refer to Figure 9 ST22 and ST23 are described in the diagram. During the transport of the third print media P, the upstream end of the third print media P in the transport direction reaches a position corresponding to the timing at which the second print media P begins to be fed from the second transport path 101 by the intermediate roller 15. Then, in the second drive switch state, the first feed motor driver 210 drives the first feed motor 206 in reverse at low speed. As a result, the intermediate roller 15 and the feed roller 3... Figure 1 The STC rotates at 7.6 inches per second in the direction of arrow B. Then, the intermediate roller 15 and feed roller 3 transport the second print media P from the second transport path 101 to the first transport path 100 in the direction of the transport roller 5. At this time, the printhead 7 is performing an image forming operation on the third print media P based on the print data. When the print media sensor 16 senses the downstream leading edge of the second print media P in the transport direction, the first feed motor 206 switches to high-speed drive while continuing the reverse drive in the second drive switch state. In other words, the intermediate roller 15 and feed roller 3 rotate at 20 inches per second.

[0104] At this time, similar to the operation described above, before the first feed motor 206 switches to high-speed drive, the values ​​of the upstream end of the preceding print medium P in the transport direction and the downstream front end of the subsequent print medium P in the transport direction stored in RAM 203 are checked. In other words, the value of K(3) in the K region of the upstream end of the third print medium P and the value of K(2) in the downstream front end stored in RAM 203 when printing onto the rear end of the first surface of the second print medium P are checked. "Downstream front end of the second print medium P within the second transport path 101" means the upstream rear end in the first transport path 100 before reversal. If both K(3) and K(2) are 0, the first feed motor 206 switches to high-speed drive. If K(3) or K(2) is 1, the preceding and subsequent print media may not overlap due to the curling of the print medium P, so the first feed motor 206 does not switch to high-speed drive. At this stage, the value of K(3) in the K region of the third print medium P is initially 0 because the image data has not yet been printed. Therefore, when K(2) is 1, the first feed motor 206 does not switch to high-speed drive, and the downstream front end of the second printing medium P in the conveying direction does not overlap with the upstream end of the third printing medium P in the conveying direction. The explanation will continue with the case where K(2) is 0 and the first feed motor 206 switches to high-speed drive.

[0105] Compared to the downstream movement speed of the third printing medium P as a result of the printing operation of printhead 7, the second printing medium P moves at a higher speed, enabling the front end of the second printing medium P to overlap with the rear end of the third printing medium P. The printing operation is performed based on the printing data of the third printing medium P, and thus the third printing medium P is intermittently conveyed by the transport roller 5. On the other hand, after the printing medium sensor 16 senses the leading edge of the second printing medium P, the feed roller 3 and the intermediate roller 15 rotate continuously at 20 inches per second, allowing the second printing medium P to catch up with the third printing medium P. Then, the feed roller 3 conveys the second printing medium P until its downstream leading edge in the conveying direction stops at a predetermined position upstream of the transport roller gap. The position of the leading edge of the second printing medium P is calculated based on the amount of rotation of the feed roller 3 after the printing medium sensor 16 senses the leading edge of the second printing medium P, and the position of the leading edge of the second printing medium P is controlled based on the result of this calculation. Meanwhile, printhead 7 is performing an image forming operation on the third printing medium P based on the printing data.

[0106] Now refer to Figure 9 ST24 in the document describes the process. When the transport roller 5 is stopped to perform an image forming operation (ink jetting operation) on the final row of the third print media P, a skew correction operation for the second print media P is performed by driving the feed roller 3 so that the downstream front end of the second print media P in the transport direction contacts the gap of the transport roller.

[0107] Now refer to Figure 10 ST25 in the document provides a description. When the image forming operation for the final line of the third print medium P is completed, the second print medium P can be aligned by rotating the transfer roller 5 by a predetermined amount and keeping the second print medium P overlapping the third print medium P.

[0108] As previously described, after the pickup roller 2 feeds the second print medium P from the paper loading unit 11, it is determined whether the print medium P to be aligned has already been fed from the paper loading unit 11. When it is determined that the print medium P has been fed from the second transport path 101, it is further determined whether the print data of the second side of the print medium P that was immediately in the print operation is the final print data in a job. When it is determined that the print medium P to be aligned has been fed from the second transport path 101 and the print data of the second side of the print medium P that was immediately in the print operation is the final print data in a job, the following control is performed. That is, the next print medium P after the print medium P to be aligned is selected and fed from the second transport path to a position opposite to the print head 7. Additionally, if it is determined that the print medium P to be aligned has been fed from the second transport path 101 and the print data of the second side of the print medium P that was immediately in the print operation is not the final print data in a job, the following control is performed. That is, the next print medium P after the print medium P to be aligned is selected and fed from the paper loading unit 11 to a position opposite to the print head 7.

[0109] In this determination, it is determined that the second printing medium P is fed from the second transport path 101, and the printing data on the second side of the third printing medium P is the final printing data in a job. Accordingly, the next printing medium P after the second printing medium P to be aligned is fed from the second transport path 101 to a position opposite to the print head 7. It is also necessary to ensure that the next printing medium P after the second printing medium P to be aligned is not fed from the paper loading unit 11 with a delay. In addition, the second printing medium P is being fed from the second transport path 101. Therefore, during the alignment of the second printing medium P, control is performed such that the first feed motor 206 is driven in reverse in the second drive switch state, and the feed roller 3 and the intermediate roller 15 are driven together with the transport roller 5 without driving the pickup roller 2.

[0110] Once the second print media P is aligned, the first feed motor 206 switches to low-speed drive while continuing its reverse drive in the second drive switch state. In other words, the feed roller 3 and the intermediate roller rotate at 7.6 inches per second. The conveyor roller 5 intermittently conveys the second print media P in a predetermined amount each time. The printhead 7 performs the printing operation on the second print media P based on the printing data. While the second print media P is intermittently conveyed for printing operations, the third print media P is also intermittently conveyed.

[0111] Now refer to Figure 10ST26 in the document describes the process. After determining that the upstream end of the third printing medium P in the conveying direction has passed the ratchet 12 based on the rotation amount of the conveying roller 5 from the start of the alignment operation and the length of the sheet, the second feed motor driver 211 causes the second feed motor 207 to rotate at high speed in the forward direction. The reverse roller 9... Figure 1 The reverse roller 9 rotates at 18 inches per second in the direction of arrow A. As a result, the reverse roller 9 conveys the third print media P faster than the conveyor roller 5 conveys the second print media P. The upstream end of the third print media P in the conveying direction and the downstream front end of the second print media P in the conveying direction no longer overlap. Then, after being reversed by the reverse roller 9, the third print media P enters the second conveyor path 101, and its upstream rear end in the conveying direction passes through the reverse roller 9, while the downstream front end of the second print media P in the conveying direction can pass through the reverse roller 9. "Upstream rear end of the third print media P in the second conveyor path 101" means the downstream front end in the first conveyor path 100 before reversal.

[0112] When the reverse roller 9 is Figure 1 When rotating in the direction of arrow A in STA, in Figure 1 The third printing medium P is conveyed in the direction of arrow C in the STA. As a result, the third printing medium P is continuously conveyed until its upstream end in the conveying direction reaches the predetermined position of the reverse roller 9 upstream in the conveying direction. Therefore, the upstream end of the third printing medium P in the conveying direction and the downstream front end of the second printing medium P, which is being conveyed intermittently in a predetermined amount, are pulled apart.

[0113] Now refer to Figure 10 ST27 in the document describes this. When the third printing medium P reaches the predetermined position on the upstream side of the reverse roller 9 in the conveying direction, the second feed motor driver 211 drives the second feed motor 207 in reverse at high speed. As a result, the reverse roller 9 and the intermediate roller 15... Figure 1 The STC rotates at 18 inches per second in the direction of arrow B. Then, the reverse roller 9 and the intermediate roller 15 convey the third printing medium P along the guide within the second conveying path (reverse path) 101 until its downstream leading edge in the conveying direction reaches a predetermined position before the first conveying path 100. This predetermined position is also calculated based on the amount of rotation of the conveying roller 5 since the start of the alignment operation and the length of the sheet.

[0114] Now refer to Figure 11ST28 in the description is given. During the transport of the second print media P, the upstream end of the second print media P in the transport direction reaches a position corresponding to the timing at which the third print media P begins to be fed from the second transport path 101 by the intermediate roller 15 (described later). Then, in the second drive switch state, the first feed motor driver 210 drives the first feed motor 206 in reverse at low speed. As a result, the intermediate roller 15 and the feed roller 3... Figure 1 The STC rotates at 7.6 inches per second in the direction of arrow B. Then, the intermediate roller 15 and feed roller 3 transport the third print media P from the second transport path 101 to the first transport path 100 in the direction of the transport roller 5. At this time, the printhead 7 is performing an image forming operation on the second print media P based on print data. When the print media sensor 16 senses the downstream leading edge of the third print media P in the transport direction, the first feed motor 206 switches to high-speed drive while maintaining reverse drive in the second drive switch state. In other words, the intermediate roller 15 and feed roller 3 rotate at 20 inches per second.

[0115] At this time, similar to the aforementioned conditions, before the first feed motor 206 switches to high-speed drive, the values ​​of the upstream end of the preceding print medium P in the transport direction and the downstream front end of the subsequent print medium P in the transport direction stored in RAM 203 are checked. In other words, the values ​​of S(2) stored in RAM 203 when printing to the front end of the first surface of the second print medium P and K(3) stored in RAM 203 when printing to the rear end of the first surface of the third print medium P are checked. "Downstream front end of the third print medium P within the second transport path 101" means the upstream end (rear end) in the first transport path 100 before reversal. If both S(2) and K(3) are 0, the first feed motor 206 switches to high-speed drive. If S(2) or K(3) is 1, the preceding and subsequent print media may not overlap due to the curling of the print medium P. Accordingly, the first feed motor 206 does not switch to high-speed drive. The explanation will continue with the case where the values ​​of S(2) and K(3) are 0 and the first feed motor 206 is switched to high-speed drive.

[0116] Compared to the downstream movement speed of the second printing medium P as a result of the printing operation of printhead 7, the third printing medium P moves at a higher speed, enabling the front end of the third printing medium P to overlap with the rear end of the second printing medium P. The printing operation is performed based on the printing data of the second printing medium P, and thus the second printing medium P is intermittently conveyed by the transport roller 5. On the other hand, after the printing medium sensor 16 senses the leading edge of the third printing medium P, the feed roller 3 and the intermediate roller 15 rotate continuously at 20 inches per second, allowing the third printing medium P to catch up with the second printing medium P. Then, the feed roller 3 conveys the third printing medium P until its downstream leading edge in the transport direction stops at a predetermined position upstream of the transport roller gap. The position of the downstream leading edge of the third printing medium P in the transport direction is calculated based on the amount of rotation of the feed roller 3 after the printing medium sensor 16 senses the downstream leading edge of the third printing medium P in the transport direction, and the position of the downstream leading edge of the third printing medium P in the transport direction is controlled based on the result of this calculation. At this time, printhead 7 is performing an image forming operation on the second printing medium P based on the printing data.

[0117] Now refer to Figure 11 ST29 in the document describes the process. When the transport roller 5 is stopped to perform an image forming operation (ink jetting operation) on the final line of the second print media P, a skew correction operation for the third print media P is performed by driving the feed roller 3 so that the downstream leading edge of the third print media P in the transport direction contacts the gap of the transport roller. When the image forming operation on the final line of the second print media P is completed, the third print media P can be aligned by rotating the transport roller 5 by a predetermined amount and keeping the third print media P overlapping the second print media P.

[0118] Once the skew correction operation for the third print media P is complete, the conveyor roller 5 begins to rotate as a result of being driven by the conveyor motor 205. The conveyor roller 5 conveys the print media at a rate of 15 inches per second. After aligning the third print media P with the position opposite the print head 7, the print head 7 ejects ink based on the print data to print the sixth page of print data.

[0119] After determining that the upstream end of the second printing medium P has passed the ratchet 12 in the conveying direction based on the rotation amount of the conveying roller 5 from the start of the alignment operation and the length of the sheet, the second feed motor driver 211 causes the second feed motor 207 to rotate at high speed in the forward direction. The reverse roller 9... Figure 1The STA rotates at 18 inches per second in the direction of arrow A. As a result, the reverse roller 9 conveys the second print media P faster than the conveyor roller 5 conveys the third print media P. The upstream end of the second print media P in the conveying direction and the downstream front end of the third print media P in the conveying direction no longer overlap. Printing of the first and second sides of the second print media P is completed, and thus, through the reverse roller 9... Figure 1 The STA rotates at 18 inches per second in the direction of arrow A, expelling the second print media P to the outside of the device.

[0120] When the image forming operation for the final row of the third printing medium P is completed, the printing of the first and second sides of the third printing medium P, which is the final printing medium in a job, is finished. Therefore, the reverse roller 9... Figure 1 The STA rotates at 18 inches per second in the direction of arrow A. The discharge roller 10 and the transfer roller 5 also rotate at 18 inches per second in the same direction as the reverse roller 9, which discharges the third print media P to the outside of the device and completes the double-sided printing.

[0121] Figures 12 to 18B This is a flowchart illustrating the overlapping continuous feed operation in the duplex printing mode according to this embodiment. The following describes the case of printing six pages of print data on the first and second surfaces of three print media P, wherein the first surface of the print media P is the surface on which the printing operation is performed first, and the second surface is the back surface of the first surface.

[0122] exist Figure 12 In step S1, when print data in duplex printing mode is sent from host computer 214 via I / F unit 213, duplex printing mode printing operation begins.

[0123] In step S2, N=1 is stored in RAM 203 as an initial value for managing how many sheets of print media P have been fed from the paper loading unit 11 in a job. In step S3, F=0 is stored in RAM 203 as an initial value for managing whether print media P has been printed onto the first or second side. Note that F=0 indicates printing onto the first side, and F=1 indicates printing onto the second side. In step S4, P=0 is stored in RAM 203 as an initial value for managing whether the operation of feeding print media P to the position opposite the printhead 7 begins from the paper loading unit 11 or from the second transport path 101. Note that P=0 indicates feeding from the paper loading unit 11, and P=1 indicates feeding from the second transport path 101.

[0124] In step S5, when it is determined that the printing medium P fed from the paper loading unit 11 is the first sheet in the job, the processing moves to... Figure 13 The "Feed 1 from paper loading unit" subroutine is shown in step S30.

[0125] In step S31, the feeding operation of the first print media P begins from the paper loading unit 11. Specifically, the first feed motor 206 is driven forward at a low speed. The pickup roller 2 rotates at 7.6 inches per second. As a result, the first print media P is picked up by the pickup roller 2 and fed towards the print head 7 by the feed roller 3.

[0126] In step S32, P=0 is stored in RAM 203 to store an indication that print media P has been fed from paper loading unit 11. In step S33, when print media sensor 16 senses the downstream leading edge of the first print media P in the transport direction, in step S34, the first feed motor 206 switches to high-speed drive. In other words, pickup roller 2 and feed roller 3 rotate at 20 inches / second. After print media sensor 16 senses the downstream leading edge of the first print media P in the transport direction, the rotation amount of feed roller 3 is controlled. As a result, in step S35, a skew correction operation of the first print media P is performed by bringing the downstream leading edge of the first print media P in the transport direction into contact with the gap of the transport rollers.

[0127] In step S36, the first print media P is aligned based on the print data. In other words, the first print media P is conveyed to the print start position based on the position of the transfer roller 5, using the rotation amount of the transfer roller 5 as a reference, by controlling the rotation amount of the transfer roller 5. In step S37, the first feed motor 206 switches to low-speed drive. As a result, the pickup roller 2 and the feed roller 3 rotate at 7.6 inches / second. In step S38, the "Feed from paper loading unit 1" subroutine ends, and the process moves to... Figure 12 The "Print Operation" subroutine in step S8.

[0128] Reference Figure 15 The "printing operation" subroutine is described. In step S15, when it is determined that the number of sheets of printing medium P fed from the paper loading unit 11 in a job is one sheet, in step S16, a printing operation is performed on the first side of the first printing medium P by ejecting ink from the print head 7 based on the first page printing data. Specifically, the conveying operation of intermittently conveying the first printing medium P by the conveyor roller 5 and the image forming operation (ink ejection operation) of moving the carriage 1 and ejecting ink from the print head 7 are repeated. As a result, a printing operation is performed on the first side of the first printing medium P.

[0129] The first feed motor 206 is driven intermittently at low speed in sync with the operation of the transfer roller 5, which intermittently transports the first print media P. In other words, the pick-up roller 2 and the feed roller 3 rotate intermittently at 7.6 inches per second.

[0130] Here, as Figure 25 As shown, the length of the printing medium P in the transport direction is represented by L. The print density of region S ((1 / 4)L portion) at the leading end of the first printing medium P in the transport direction at the current stage indicated by arrow A is compared with the preset print density. If, as a result of the comparison, the print density of region S is within the preset print density, S(1) = 0 is stored in RAM 203; otherwise, S(1) = 1 is stored. The numbers in parentheses indicate the number of sheets printed.

[0131] Additionally, while printing on the first print media P is in progress, the print density of region K ((1 / 4)L portion) at the rear end of the first print media in the transport direction at the current stage indicated by arrow A is compared with a preset print density. If, as a result of the comparison, the print density of region K is within the preset print density, K(1) = 0 is stored in RAM 203; otherwise, K(1) = 1 is stored. Here, the number in parentheses also indicates the number of sheets printed.

[0132] Additionally, such as Figure 26 As shown, when the number of prints N of the printing medium P becomes at least four, the value of N in S(N) and K(N) is converted to the value of M in the table, and overwritten in the storage areas of S(M) and K(M) as needed.

[0133] In step S17, it is determined whether there is a second page of print data. If it is determined that there is no second page of print data, in step S130, the process moves to... Figure 17 The "Discharge Operation 2" subroutine.

[0134] In step S131, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the first printing medium P in the conveying direction has passed the ratchet 12, in step S132, the reverse roller 9 is continuously driven forward at 18 inches / second. Then, in step S133, the first printing medium P is discharged to the outside of the device, and in step S134, the "discharge operation 2" subroutine ends. Then, in Figure 15 In step S176, double-sided printing is completed.

[0135] In step S17, if it is determined that there is a second page of print data, then in step S18, F=0 is stored in RAM 203 to store an indication that a printing operation has been performed on the first surface of the print medium P, and in step S40, the process moves to... Figure 13 The "Feed from Paper Loading Unit 2" subroutine.

[0136] In step S41, after the first print media P has passed the pick-up roller 2 at its upstream end in the transport direction and the drive shaft 19 has been driven for a predetermined length of time, the second print media P is picked up. Specifically, the second print media P is picked up from the paper loading unit 11 at a rate of 7.6 inches / second via the pick-up roller 2 (delayed feed). In step S42, P=0 is stored in RAM 203 to store an indication that the second print media P has been fed from the paper loading unit 11.

[0137] In step S43, when the print media sensor 16 senses the downstream leading edge of the second print media P in the transport direction, in step S44, the first feed motor 206 switches to high-speed drive. In other words, the pickup roller 2 and the feed roller 3 rotate at 20 inches / second. After the print media sensor 16 senses the downstream leading edge of the second print media P in the transport direction, the rotation amount of the feed roller 3 is controlled. As a result, in step S45, the second print media P stops at a position 10 mm before the gap of the transport rollers at its downstream leading edge in the transport direction. Then, in step S46, N is incremented by 1, and N=2 is stored in RAM 203 to store an indication that the second print media P has been fed from the paper loading unit 11 in a job. In step S47, the "feed from paper loading unit 2" subroutine ends, and the process moves to... Figure 15 Step S19 in the process.

[0138] In step S19, it is determined whether a predetermined condition is met for the downstream front end of the subsequent printing medium P in the transport direction to overlap with the upstream front end of the preceding printing medium P in the transport direction. This predetermined condition will be described later. If it is determined in step S19 that the predetermined condition is not met, then in step S210, the process moves to the "overlap state release" subroutine.

[0139] Reference Figure 18A and Figure 18BThe "overlap state release" subroutine is described. In step S211, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first side of the printing medium P), then in step S212, it is determined whether the value of P stored in RAM 203 is 0. Here, 0 is stored in step S42, so the process moves to step S213. In step S213, when it is determined that the image forming operation for the final line of the first printing medium P is complete, in step S214, the first printing medium P is conveyed by the conveyor roller 5 and the discharge roller 10 at 18 inches / second.

[0140] In step S215, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the first printing medium P in the conveying direction has passed the ratchet 12, in step S216, the drive of the conveyor motor 205 is stopped. The first feed motor 206 is not driven until the drive of the conveyor motor 205 stops, and thus the second printing medium P remains stopped with its downstream leading edge in the conveying direction 10 mm before the conveyor roller gap. In this way, the overlap between the first and second printing media P is released. Additionally, in step S217, the first printing medium P is continued to be conveyed by continuously driving the reverse roller 9 forward at 18 inches / second until its upstream end in the conveying direction reaches a position 5 mm upstream of the roll gap of the reverse roller 9 in the conveying direction.

[0141] In step S218, the feed roller 3 is driven at 15 inches / second to bring the leading edge of the second print media P into contact with the gap of the transport roller, and a skew correction operation is performed on the second print media P. In step S219, the second print media P is aligned based on the print data. In other words, by controlling the rotation of the transport roller 5, the second print media P is conveyed to the print start position based on the position of the transport roller 5 according to the print data. Then, in step S220, the first feed motor 206 switches to low-speed drive, and the feed roller 3 rotates at 7.6 inches / second.

[0142] In step S221, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the first print media P along the guide within the second conveying path 101. Then, in step S222, the reverse roller 9 and intermediate roller 15 convey the first print media P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop. Processing then returns to... Figure 15 The process continues with step S22, and the second printing medium P is processed from step S22 onwards.

[0143] In step S19, if it is determined that a predetermined condition is met, then in step S20, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first surface of the printing medium P), then in step S21, it is determined whether the value of P stored in RAM 203 is 0. Here, 0 is stored in step S42, so in step S70, the process moves to the "Print Operation 1" subroutine.

[0144] Reference Figure 16 The "Print Operation 1" subroutine is described. In step S71, it is determined whether the image forming operation for the final line of the first print medium P has started. If the image forming operation has started, in step S72, while maintaining the overlapping state, a skew correction operation for the second print medium P is performed by contacting the downstream front end of the second print medium P with the gap of the conveyor rollers in the conveying direction. Then, in step S73, when it is determined that the image forming operation for the final line of the first print medium P is completed, in step S74, while maintaining the overlapping state with the first print medium P, the second print medium P is aligned based on the print data. In other words, by controlling the rotation amount of the conveyor roller 5, the second print medium P is conveyed to the printing start position based on the position of the conveyor roller 5 based on the print data. In step S75, the first feed motor 206 switches to low-speed drive, and in step S76, the "Print Operation 1" subroutine ends, and processing returns to... Figure 15 Step S22 in the printing operation sequence.

[0145] In step S22, for the first side of the second printing medium P, the printing operation on the first side of the second printing medium P is started by ejecting ink from the print head 7 based on the printing data of the third page. Specifically, the printing operation on the first side of the second printing medium P is performed by repeatedly conveying the second printing medium P intermittently by the conveyor roller 5 and by moving the carriage 1 and ejecting ink from the print head 7 (ink ejection operation). Then, in step S23, F=0 is stored in RAM 203 to store an indication that a printing operation has been performed on the first side of the printing medium P, and in step S25, the "printing operation" subroutine ends.

[0146] Here, as mentioned before, such as Figure 25 As shown, the length of the printing medium P in the conveying direction is represented by L. When printing onto the first surface of the printing medium P, [the following will occur]. Figure 25The print density of region S ((1 / 4)L portion) at the leading end in the conveying direction, as indicated by arrow A in the diagram, is compared with the preset print density. If, as a result of the comparison, the print density of region S is within the preset print density, then S(2) = 0 is stored in RAM 203; otherwise, S(2) = 1 is stored. The numbers in parentheses indicate the number of sheets printed.

[0147] Additionally, while printing on the second printing medium P is in progress, the print density of region K ((1 / 4)L portion) at the rear end in the transport direction of the current stage, as indicated by arrow A, is compared with a preset print density. If, as a result of the comparison, the print density of region K is within the preset print density, K(2) = 0 is stored in RAM 203; otherwise, K(2) = 1 is stored.

[0148] Additionally, such as Figure 26 As shown, when the number of sheets N of the printing medium P becomes at least four, the value of N in S(N) and K(N) is converted to the value of M in the table, and overwritten in the storage areas of S(M) and K(M) as needed.

[0149] Return to Figure 12 In step S210, it is determined whether F stored in RAM 203 is 0. At the current stage, F = 0, therefore in step S211, it is determined whether N stored in RAM 203 is 2. At the current stage, N = 2, therefore the process moves to step S101.

[0150] In step S101, it is determined whether the printing operation of the printing medium P is for the first side. Currently, the F value in RAM203 is 0, and it is determined that the printing operation of the printing medium P is for the first side, and the process moves to step S102. In step S102, when it is determined that the upstream end of the first printing medium P in the conveying direction has passed the ratchet 12, in step S103, the reverse roller 9 is continuously driven forward at 18 inches / second. In the forward drive, the drive is continuously performed until the upstream end of the first printing medium P in the conveying direction reaches a position 5 mm upstream of the roll gap of the reverse roller 9 in the conveying direction.

[0151] In step S104, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the first print media P along the guide within the second conveying path 101. Then, in step S105, the reverse roller 9 and intermediate roller 15 convey the first print media P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop, after which the process moves to step S5.

[0152] In step S5, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=2 in the current stage), in step S6, it is determined whether F in RAM 203 is 1. In the current stage, F=0, therefore in step S60, the process moves to the "Feed 1 from the second transport path" subroutine.

[0153] Reference Figure 14 The subroutine "Feeding from the second transport path 1" is described. In step S61, it is determined whether the timing for the start intermediate roller 15 to feed the first print medium P from the second transport path 101 has been reached. When the print medium P, which is being printed by the print head 7, is fed from the paper loading unit 11, and the subsequent print medium P is fed from the second transport path 101, the timing for the feed of the start intermediate roller 15 is as follows. This time corresponds to the timing for the start of feed when the positional relationship between the rotation amount of the transport roller 5 from the start of the alignment operation, the length of the paper, the upstream end of the second print medium P in the transport direction, and the downstream front end of the first print medium P waiting in the second transport path 101 reaches a distance of 10 mm from each other. Based on this relationship, the start intermediate roller 15 is driven so that the start intermediate roller 15 feeds the first print medium P from the second transport path 101.

[0154] In step S62, the feeding operation of the first print media P begins from the second transport path 101. Specifically, the first feed motor 206 is driven in reverse at low speed in the second drive switch state. As a result, the intermediate roller 15 and the feed roller 3 rotate at 7.6 inches / second. Then, the intermediate roller 15 and the feed roller 3 feed the first print media P toward the print head 7.

[0155] In step S63, P=1 is stored in RAM 203 to store an indication that the printing medium P has been fed from the second transport path 101. In step S64, when the printing medium sensor 16 senses the downstream leading edge of the first printing medium P in the transport direction, in step S65, it is determined whether K(2)=0 and K(1)=0 in RAM 203. Here, the first printing medium P, which is the subsequent printing medium, has been reversed by the reversing roller 9 and is being transported by the second transport path 101. Accordingly, the downstream leading edge of the first printing medium, which is the subsequent printing medium, overlaps with the rear end of the second printing medium P, which is used as the preceding printing medium, and is the upstream rear end of the first transport path 100. Figure 25 (K region in RAM 203). Therefore, in step S65, it is determined whether K(2) = 0 and K(1) = 0 in RAM 203.

[0156] If either is determined to be 1, the preceding and subsequent printing media may not be able to overlap due to the curling of the printing media P, so the first feed motor 206 does not switch to high-speed drive.

[0157] Therefore, the intermediate roller 15 and feed roller 3 are still driven synchronously with the transfer roller 5 at 7.6 inches / second, and the process moves to step S67. Then, in step S67, after the print media sensor 16 senses the downstream leading edge of the first print media P in the conveying direction, the rotation amount of the feed roller 3 is controlled. As a result, the conveying of the first print media P stops when the downstream leading edge of the first print media P in the conveying direction reaches a position 10 mm before the gap of the transfer roller. Then, in step S68, the "Feed from the second conveying path 1" subroutine ends.

[0158] In step S65, when it is determined that K(2) = 0 and K(1) = 0 in RAM 203, in step S66, the first feed motor 206 switches to high-speed drive. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / second. After the print media sensor 16 senses the downstream front end of the first print media P in the conveying direction, the rotation amount of the intermediate roller 15 and the feed roller 3 is controlled. As a result, in step S67, the first print media P stops when the downstream front end of the first print media P in the conveying direction is 10 mm before the gap of the conveyor rollers. Then, in step S68, the "Feed from the second conveying path 1" subroutine ends, and processing returns to Figure 12 The entire sequence is processed and moved to the "print operation" subroutine in step S8.

[0159] Reference Figure 15 The "Print Operation" subroutine is described. In step S15, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=2 in the current stage), it is determined in step S19 whether a predetermined condition is met (described later). In step S19, if it is determined that the predetermined condition is not met, the process moves to the "Overlap State Removal" subroutine in step S210.

[0160] Reference Figure 18A and Figure 18BThe "overlap state release" subroutine is described. In step S211, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first side of the printing medium P), then in step S212, it is determined whether the value of P stored in RAM 203 is 0. Here, 1 is stored in step S63, so the process moves to step S224. In step S224, when it is determined that the image forming operation for the final line of the second printing medium P is complete, in step S225, the second printing medium P is conveyed by the conveyor roller 5 and the discharge roller 10 at 18 inches / second.

[0161] In step S226, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the second printing medium P in the conveying direction has passed the ratchet 12, in step S227, the drive of the conveyor motor 205 is stopped. The first feed motor 206 is not driven until the drive of the conveyor motor 205 stops, and thus the first printing medium P remains stopped with its downstream leading edge in the conveying direction 10 mm before the conveyor roller gap. In this way, the overlap between the second printing medium P and the first printing medium P is released. Additionally, in step S228, the second printing medium P is continued to be conveyed by continuously driving the reverse roller 9 forward at 18 inches / second until its upstream end in the conveying direction reaches a position 5 mm upstream of the roll gap of the reverse roller 9 in the conveying direction.

[0162] In step S229, the feed roller 3 is driven at 15 inches / second to bring the leading edge of the first print media P into contact with the gap of the transport roller, and a skew correction operation is performed on the first print media P. In step S230, the first print media P is aligned based on the print data. In other words, by controlling the rotation of the transport roller 5, the first print media P is conveyed to a print start position based on the position of the transport roller 5 according to the print data. Then, in step S231, the first feed motor 206 switches to low-speed drive, and the feed roller 3 rotates at 7.6 inches / second.

[0163] In step S232, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the second printing medium P along the guide within the second conveying path 101. Then, in step S233, the reverse roller 9 and intermediate roller 15 convey the second printing medium P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop. The process then returns to... Figure 15 The process proceeds to step S170, and the first printing medium P is processed from step S170 onwards.

[0164] In step S19, if it is determined that a predetermined condition is met, then in step S20, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first surface of the printing medium P), then in step S21, it is determined whether the value of P stored in RAM 203 is 0. 1 is stored in the current stage, and therefore, in step S80, the process moves to the "Print Operation 2" subroutine.

[0165] Reference Figure 16 The "Print Operation 2" subroutine is described. In step S81, it is determined whether the image forming operation for the final line of the second print medium P has started. If the image forming operation has started, in step S82, while maintaining the overlapping state, a skew correction operation for the first print medium P is performed by contacting the downstream front end of the first print medium P with the gap of the conveyor rollers in the conveying direction. Then, in step S83, when it is determined that the image forming operation for the final line of the second print medium P is completed, in step S84, while maintaining the overlapping state with the second print medium P, the first print medium P is aligned based on the print data. In other words, by controlling the rotation amount of the conveyor roller 5, the first print medium P is conveyed to the printing start position based on the position of the conveyor roller 5 based on the print data. In step S85, the first feed motor 206 switches to low-speed drive, and in step S86, the "Print Operation 2" subroutine ends, and processing returns to... Figure 15 Step S170 in the “Print Operation” subroutine.

[0166] In step S170, the printing operation on the second side of the first printing medium P begins by ejecting ink from the print head 7 based on the second page printing data. Specifically, the printing operation on the second side of the first printing medium P is performed by repeatedly conveying the first printing medium P intermittently by the conveyor roller 5 and by moving the carriage 1 and ejecting ink from the print head 7 (ink ejection operation). Then, in step S24, F=1 is stored in RAM 203 to store an indication that a printing operation has been performed on the second side of the printing medium P, and in step S25, the "printing operation" subroutine ends.

[0167] Return to Figure 12In step S210, it is determined whether F stored in RAM 203 is 0. At the current stage, F = 1. Therefore, when it is determined in step S181 that the upstream end of the second printing medium P in the conveying direction has passed the ratchet 12, in step S182, the reverse roller 9 is continuously driven forward at 18 inches / second. During the forward drive, the drive continues until the upstream end of the second printing medium P in the conveying direction reaches a position 5 mm upstream of the roll gap of the reverse roller 9 in the conveying direction.

[0168] In step S183, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the second printing medium P along the guide within the second conveying path 101. Then, in step S184, the reverse roller 9 and intermediate roller 15 convey the second printing medium P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop, after which the process moves to step S5.

[0169] In step S5, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=2 in the current stage), in step S6 it is determined whether F in RAM 203 is 1. In the current stage F=1, therefore in step S7 it is determined whether there is a fifth page or more of print data, and if such print data exists, then in step S50 the process moves to the "feed from paper loading unit 3" subroutine.

[0170] Reference Figure 13The subroutine "Feeding from Paper Loading Unit 3" is described. In step S51, it is determined whether the timing for starting the pickup roller 2 to feed the third print medium P from the paper loading unit 11 has been reached. When the print medium P being printed by the print head 7 is being fed from the second transport path 101, and the subsequent print medium P is being fed from the paper loading unit 11, the timing for starting the pickup roller 2 to feed is as follows. Assume that the first print medium P being printed by the print head 7 is being transported in the first transport path 100. Based on the rotation amount of the transport roller 5 from the start of the alignment operation and the length of the paper, and assuming that the upstream end of the first print medium P in the transport direction and the downstream front end of the third print medium P waiting in the paper loading unit 11 are 10 mm apart, this time corresponds to the time when the feed begins. Based on this relationship, the start pickup roller 2 is driven so that the start pickup roller 2 feeds the third print medium P from the paper loading unit 11. In step S51, when it is determined that the timing for starting feeding has been reached, in step S52, the third print medium P begins to be fed from the paper loading unit 11 by the pickup roller 2 at 7.6 inches / second. In step S53, P=0 is stored in RAM 203 to store an indication that print medium P has been fed from the paper loading unit 11 toward the print head 7.

[0171] In step S54, when the printing medium sensor 16 senses the downstream leading edge of the third printing medium P in the conveying direction, in step S55, it is determined whether S(1) = 0 and S(3) = 0 in RAM 203. Here, the first printing medium P, which is the preceding printing medium, has been reversed by the reversing roller 9 and is being conveyed by the second conveying path 101. Accordingly, the rear end of the first printing medium P, which is the preceding printing medium and overlaps with the leading end of the third printing medium used as the subsequent printing medium, is the downstream leading edge in the first conveying path 100. Figure 25 (In the S region). Therefore, in step S55, it is determined whether S(1) = 0 and S(3) = 0 in RAM203.

[0172] If either is determined to be 1, the preceding and subsequent printing media may not overlap due to the curling of printing media P, therefore the first feed motor 206 does not switch to high-speed drive. Thus, the pick-up roller 2 and feed roller 3 are still driven synchronously with the transport roller 5 at 7.6 inches / second, and processing moves to step S57. Then, in step S57, after the printing media sensor 16 senses the downstream leading edge of the third printing media P in the transport direction, the rotation amount of the feed roller 3 is controlled. As a result, the transport of the third printing media P stops when the downstream leading edge of the third printing media P reaches a position 10 mm before the gap of the transport rollers. Then, in step S58, the value of N in RAM 203 is incremented by 1 to make N = 3, and in step S59, the "feed from paper loading unit 3" subroutine ends.

[0173] In step S55, when it is determined that S(1) = 0 and S(3) = 0 in RAM 203, in step S56, the first feed motor 206 switches to high-speed drive. In other words, the pickup roller 2 and the feed roller 3 rotate at 20 inches / second. Then, after the print media sensor 16 senses the downstream front end of the third print media P in the transport direction, the rotation amount of the feed roller 3 is controlled. As a result, in step S57, the third print media P is transported such that the downstream front end of the third print media P in the transport direction reaches a position 10 mm before the gap of the transport rollers. The first print media P is transported intermittently based on the print data. By continuously driving the first feed motor 206 at high speed, a state is created where the third print media P near the downstream front end in the transport direction overlaps with the first print media P near the upstream end in the transport direction. In step S58, the value of N in RAM 203 is incremented by 1 so that N = 3, and in step S59, the "feed 3 from paper loading unit" subroutine ends. Then, the process returns to Figure 12 The entire sequence in the sequence is processed, and in step S8, the process moves to the "print operation" subroutine.

[0174] Reference Figure 15 The "Print Operation" subroutine is described. In step S15, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=3 in the current stage), it is determined in step S19 whether a predetermined condition is met (described later). In step S19, if it is determined that the predetermined condition is not met, the process moves to the "Overlap State Removal" subroutine in step S210.

[0175] Reference Figure 18A and Figure 18BThe "overlap state release" subroutine is described. In step S211, the value of F in RAM 203 is checked, and if F = 1 (i.e., if it is determined that printing is being performed on the second side of the printing medium P), then in step S234, it is determined whether the value of P stored in RAM 203 is 0. Since 0 is stored at the current stage, the process moves to step S235. In step S235, when it is determined that the image forming operation for the final line of the first printing medium P is complete, in step S236, the first printing medium P is conveyed by the conveyor roller 5 and the discharge roller 10 at 18 inches / second.

[0176] In step S237, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the first printing medium P in the conveying direction has passed the ratchet 12, in step S238, the drive of the conveyor motor 205 is stopped. The first feed motor 206 is not driven until the drive of the conveyor motor 205 stops, and thus the third printing medium P remains stopped with its downstream leading edge in the conveying direction positioned 10 mm before the gap in the conveyor rollers. In this way, the overlap between the first and third printing media P is released. Additionally, by continuously driving the reverse roller 9 forward at 18 inches / second in step S239, the first printing medium P is discharged to the outside of the device in step S240.

[0177] In step S241, the feed roller 3 is driven at 15 inches / second to bring the leading edge of the third print media P into contact with the gap of the transport roller, and a skew correction operation is performed on the third print media P. In step S242, the third print media P is aligned based on print data. In other words, by controlling the rotation of the transport roller 5, the third print media P is conveyed to a print start position referenced to the position of the transport roller 5 based on print data. Then, in step S243, the first feed motor 206 switches to low-speed drive and rotates the feed roller 3 at 7.6 inches / second. Then, processing returns to... Figure 15 The process continues with step S22, and the third printing medium P is processed from step S22 onwards.

[0178] In step S19, if it is determined that a predetermined condition is met, then in step S20, the value of F in RAM 203 is checked, and if F = 1 (i.e., if it is determined that printing is being performed on the second side of the printing medium P), then in step S172, it is determined whether the value of P stored in RAM 203 is 0. Since 0 is stored at the current stage, the process moves to the "Print Operation 3" subroutine in step S90.

[0179] Reference Figure 16The "Print Operation 3" subroutine is described. In step S91, it is determined whether the image forming operation for the final line of the first print medium P has started. If the image forming operation has started, in step S92, while maintaining the overlapping state, a skew correction operation for the third print medium P is performed by contacting the downstream front end of the third print medium P with the gap of the conveyor rollers in the conveying direction. Then, in step S93, when it is determined that the image forming operation for the final line of the first print medium P is completed, in step S94, while maintaining the overlapping state with the third print medium P, the third print medium P is aligned based on the print data. In other words, by controlling the rotation amount of the conveyor roller 5, the third print medium P is conveyed to the printing start position based on the position of the conveyor roller 5 based on the print data. In step S95, the first feed motor 206 switches to low-speed drive, and in step S96, the "Print Operation 3" subroutine ends, and processing returns to... Figure 15 Step S22 in the “Print Operation” subroutine.

[0180] In step S22, the printing operation on the first side of the third printing medium P begins by ejecting ink from the printhead 7 based on the fifth page of print data. Specifically, the printing operation on the first side of the third printing medium P is performed by repeatedly conveying the third printing medium P intermittently by the conveyor roller 5 and by moving the carriage 1 and ejecting ink from the printhead 7 (ink ejection operation). Then, in step S23, F=0 is stored in RAM 203 to store an indication that a printing operation has been performed on the first side of the printing medium P, and in step S25, the "printing operation" subroutine ends.

[0181] Here, as mentioned before, such as Figure 25 As shown, the length of the printing medium P in the conveying direction is represented by L. When printing onto the first surface of the printing medium P, [the following will occur]. Figure 25 The print density of the S region ((1 / 4)L portion) at the leading end in the conveying direction, indicated by arrow A in the diagram, is compared with the preset print density. If, as a result of the comparison, the print density of the S region is within the preset print density, then S(3) = 0 is stored in RAM 203; otherwise, S(3) = 1 is stored. The numbers in parentheses indicate the number of sheets printed.

[0182] Additionally, while the printing operation of the third printing medium P is in progress, the printing density of region K ((1 / 4)L portion) at the rear end in the transport direction of the current stage, as indicated by arrow A, is compared with the preset printing density. If, as a result of the comparison, the printing density of region K is within the preset printing density, then K(3) = 0 is stored in RAM 203; otherwise, K(3) = 1 is stored.

[0183] Additionally, such as Figure 26 As shown, when the number of sheets N of the printing medium P becomes at least four, the value of N in S(N) and K(N) is converted to the value of M in the table, and overwritten in the storage areas of S(M) and K(M) as needed.

[0184] Return to Figure 12 In step S210, it is determined whether F stored in RAM 203 is 0. At this stage, F = 0, therefore in step S211, it is determined whether N stored in RAM 203 is 2. At this stage, the value is 3, therefore in step S201, it is determined that the upstream end of the first printing medium P in the conveying direction has passed the ratchet 12 based on the rotation amount of the conveying roller 5 since the start of the alignment operation and the length of the sheet. When it is determined that the end has passed, in step S202, the reverse roller 9 is continuously driven forward at 18 inches / second. In step S203, the first printing medium P is discharged outside the device, and the process moves to step S5.

[0185] In step S5, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=3 in the current stage), in step S6, it is determined whether F in RAM 203 is 1. In the current stage, F=0, therefore in step S60, the process moves to the "Feed 1 from the second transport path" subroutine.

[0186] Reference Figure 14 The subroutine "Feeding from the second transport path 1" is described. In step S61, it is determined whether the timing for the start intermediate roller 15 to feed the second print medium P from the second transport path 101 has been reached. When the print medium P being printed by the print head 7 is fed from the paper loading unit 11, and the subsequent print medium P is fed from the second transport path 101, the timing of the feed of the start intermediate roller 15 is as follows. This time corresponds to the start time of feed when the positional relationship between the rotation amount of the transport roller 5 from the start of the alignment operation, the length of the paper, the upstream end of the third print medium P in the transport direction, and the downstream front end of the second print medium P waiting in the second transport path 101 reaches a distance of 10 mm from each other. Based on this relationship, the start intermediate roller 15 is driven so that the start intermediate roller 15 feeds the second print medium P from the second transport path 101.

[0187] In step S62, the feeding operation of the second print media P begins from the second transport path 101. Specifically, the first feed motor 206 is driven in reverse at low speed in the second drive switch state. As a result, the intermediate roller 15 and the feed roller 3 rotate at 7.6 inches / second. Then, the intermediate roller 15 and the feed roller 3 feed the second print media P toward the print head 7.

[0188] In step S63, P=1 is stored in RAM 203 to store an indication that the printing medium P has been fed from the second transport path 101. In step S64, when the printing medium sensor 16 senses the downstream leading edge of the second printing medium P in the transport direction, in step S65, it is determined whether K(3)=0 and K(2)=0 in RAM 203. Here, the second printing medium P, as the subsequent printing medium, has been reversed by the reversing roller 9 and is being transported by the second transport path 101. Accordingly, the downstream leading edge of the second printing medium, which is used as the subsequent printing medium and overlaps with the rear end of the third printing medium P used as the preceding printing medium, is the upstream rear end of the first transport path 100. Figure 25 (K region in RAM 203). Therefore, in step S65, it is determined whether K(3) = 0 and K(2) = 0 in RAM 203.

[0189] If either is determined to be 1, the preceding and subsequent printing media may not overlap due to the curling of printing media P, therefore the first feed motor 206 does not switch to high-speed drive. Thus, the intermediate roller 15 and feed roller 3 are still driven synchronously with the transfer roller 5 at 7.6 inches / second, and processing moves to step S67.

[0190] Then, in step S67, after the printing media sensor 16 senses the downstream leading edge of the second printing media P in the conveying direction, the rotation amount of the feed roller 3 is controlled. As a result, the conveying of the second printing media P stops when the downstream leading edge of the second printing media P in the conveying direction reaches a position 10 mm before the gap of the conveying roller. Then, in step S68, the "feed from the second conveying path 1" subroutine ends.

[0191] In step S65, when it is determined that K(3) = 0 and K(2) = 0 in RAM 203, in step S66, the first feed motor 206 switches to high-speed drive. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / second. After the print media sensor 16 senses the downstream leading edge of the second print media P in the conveying direction, the rotation amount of the intermediate roller 15 and the feed roller 3 is controlled. As a result, in step S67, the second print media P stops when the downstream leading edge of the second print media P in the conveying direction is 10 mm before the gap of the conveyor rollers. Then, in step S68, the "Feed from the second conveying path 1" subroutine ends, and processing returns to Figure 12 The entire sequence is processed and moved to the "print operation" subroutine in step S8.

[0192] Reference Figure 15 The "Print Operation" subroutine is described. In step S15, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=3 in the current stage), it is determined in step S19 whether a predetermined condition is met (described later). In step S19, if it is determined that the predetermined condition is not met, the process moves to the "Overlap State Removal" subroutine in step S210.

[0193] Reference Figure 18A and Figure 18BThe "overlap state release" subroutine is described. In step S211, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first side of the printing medium P), then in step S212, it is determined whether the value of P stored in RAM 203 is 0. Since 1 is stored at the current stage, the process moves to step S224. In step S224, when it is determined that the image formation operation for the final line of the third printing medium P is complete, in step S225, the third printing medium P is conveyed by the conveyor roller 5 and the discharge roller 10 at 18 inches / second. In step S226, when it is determined that the upstream end of the third printing medium P in the conveying direction has passed the ratchet 12 based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, in step S227, the drive of the conveyor motor 205 is stopped. The first feed motor 206 is not driven until the drive of the conveyor motor 205 stops, and thus the second print media P remains stopped with its downstream leading edge in the conveying direction 10 mm before the conveyor roller gap. In this way, the overlap between the third print media P and the second print media P is released. Additionally, the third print media P is continued to be conveyed by continuously driving the reverse roller 9 forward at 18 inches / second in step S228 until its upstream leading edge in the conveying direction reaches a position 5 mm upstream of the roller gap of the reverse roller 9 in the conveying direction.

[0194] In step S229, the feed roller 3 is driven at 15 inches / second to bring the leading edge of the second print media P into contact with the gap of the transport roller, and a skew correction operation is performed on the second print media P. In step S230, the second print media P is aligned based on the print data. In other words, by controlling the rotation of the transport roller 5, the second print media P is conveyed to a print start position based on the position of the transport roller 5 according to the print data. Then, in step S231, the first feed motor 206 switches to low-speed drive, and the feed roller 3 rotates at 7.6 inches / second.

[0195] In step S232, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the third printing medium P along the guide within the second conveying path 101. Then, in step S233, the reverse roller 9 and intermediate roller 15 convey the third printing medium P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop. The process then returns to... Figure 15 The process proceeds to step S170, and the second printing medium P is processed from step S170 onwards.

[0196] In step S19, if it is determined that a predetermined condition is met, then in step S20, the value of F in RAM 203 is checked, and if F = 0 (i.e., if it is determined that printing is being performed on the first surface of the printing medium P), then in step S21, it is determined whether the value of P stored in RAM 203 is 0. 1 is stored in the current stage, and therefore, in step S80, the process moves to the "Print Operation 2" subroutine.

[0197] Reference Figure 16 The "Print Operation 2" subroutine is described. In step S81, it is determined whether the image forming operation for the final line of the third print medium P has started. If the image forming operation has started, in step S82, while maintaining the overlapping state, a skew correction operation for the second print medium P is performed by contacting the downstream front end of the second print medium P with the gap of the conveyor rollers in the conveying direction. Then, in step S83, when it is determined that the image forming operation for the final line of the third print medium P is completed, in step S84, while maintaining the overlapping state with the third print medium P, the second print medium P is aligned based on the print data. In other words, by controlling the rotation amount of the conveyor roller 5, the second print medium P is conveyed to the printing start position based on the position of the conveyor roller 5 based on the print data. In step S85, the first feed motor 206 switches to low-speed drive, and in step S86, the "Print Operation 2" subroutine ends, and processing returns to... Figure 15 Step S170 in the “Print Operation” subroutine.

[0198] In step S170, the printing operation on the second side of the second printing medium P begins by ejecting ink from the print head 7 based on the fourth page of print data. Specifically, the printing operation on the second side of the second printing medium P is performed by repeatedly conveying the second printing medium P intermittently by the conveyor roller 5 and by moving the carriage 1 and ejecting ink from the print head 7 (ink ejection operation). Then, in step S24, F=1 is stored in RAM 203 to store an indication that a printing operation has been performed on the second side of the printing medium P, and in step S25, the "printing operation" subroutine ends.

[0199] Return to Figure 12 In step S210, it is determined whether F stored in RAM 203 is 0. At the current stage, F = 1. Therefore, when it is determined in step S181 that the upstream end of the third print media P in the conveying direction has passed the ratchet 12, in step S182, the reverse roller 9 is continuously driven forward at 18 inches / second. During the forward drive, the drive continues until the upstream end of the third print media P in the conveying direction reaches a position 5 mm upstream of the roll gap of the reverse roller 9 in the conveying direction.

[0200] In step S183, the reverse roller 9 and intermediate roller 15 are continuously reverse-driven at 18 inches / second. As a result, the reverse roller 9 and intermediate roller 15 convey the third print media P along the guide within the second conveying path 101. Then, in step S184, the reverse roller 9 and intermediate roller 15 convey the third print media P until its downstream leading edge in the conveying direction reaches a position 5 mm before the first conveying path 100, and then stop, after which the process moves to step S5.

[0201] In step S5, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=3 in the current stage), in step S6, it is determined whether F in RAM 203 is 1. In the current stage, F=1, therefore in step S7, it is determined whether there is a seventh page or subsequent print data. In this embodiment, there is no such print data, therefore in step S150, the process moves to the "feed from the second transport path 2" subroutine.

[0202] Reference Figure 14 The subroutine "Feeding from the second transport path 2" is described. In step S151, it is determined whether the timing for the start intermediate roller 15 to feed the third print medium P from the second transport path 101 has been reached. When the print medium P being printed by the print head 7 is fed from the second transport path 101, and when subsequent print media P are also fed from the second transport path 101, the timing for the feed of the start intermediate roller 15 is as follows. This time corresponds to the timing for the start of feed when the positional relationship between the rotation amount of the transport roller 5 since the start of the alignment operation, the length of the paper, the upstream end of the second print medium P in the transport direction, and the downstream front end of the third print medium P in the transport direction within the second transport path 101 reaches a distance of 10 mm from each other. Based on this relationship, the start intermediate roller 15 is driven so that the start intermediate roller 15 feeds the third print medium P from the second transport path 101. In step S152, the feed operation of the third print medium P begins from the second transport path 101. Specifically, in the second drive switch state, the first feed motor 206 is driven in reverse at low speed. As a result, the intermediate roller 15 and the feed roller 3 rotate at 7.6 inches / second. Then, the intermediate roller 15 and the feed roller 3 feed the third print medium P toward the print head 7. In step S153, P=1 is stored in RAM 203 to store an indication that the print medium P has been fed from the second transport path 101.

[0203] In step S154, when the print media sensor 16 senses the downstream leading edge of the third print media P in the transport direction, in step S155, it is determined whether there is a seventh page or subsequent print data. In this embodiment, although there is no seventh page or subsequent print data, the case where such print data exists will be described below.

[0204] In step S155, when it is determined that there is print data on the seventh page and beyond, the process moves to step S160, and in step S160, it is determined whether S(2) = 0 and S(4) = 0 are stored in RAM 203. If either is determined to be 1, the preceding and subsequent print media may not overlap due to the curling of print media P, so the first feed motor 206 does not switch to high-speed drive. Therefore, the intermediate roller 15 and feed roller 3 are still driven synchronously with the transfer roller 5 at 7.6 inches / second, and the process moves to step S158.

[0205] Then, in step S158, after the printing media sensor 16 senses the downstream leading edge of the fourth printing media P in the conveying direction, the rotation amount of the feed roller 3 is controlled. As a result, the conveying of the fourth printing media P stops when the downstream leading edge of the fourth printing media P in the conveying direction reaches a position 10 mm before the gap of the conveying roller. Then, in step S159, the "feed 2 from the second conveying path" subroutine ends, and processing returns to... Figure 12 The entire sequence in the sequence is processed, and in step S8, the process moves to the "print operation" subroutine.

[0206] In step S160, when it is determined that S(2) = 0 and K(4) = 0 in RAM 203, in step S157, the first feed motor 206 switches to high-speed drive. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / second. After the print media sensor 16 senses the downstream front end of the fourth print media P in the conveying direction, the rotation amount of the intermediate roller 15 and the feed roller 3 is controlled. As a result, in step S158, the fourth print media P stops when the downstream front end of the fourth print media P in the conveying direction is 10 mm before the gap of the conveyor rollers. Then, in step S159, the "feed 2 from the second conveying path" subroutine ends, and processing returns to Figure 12 The entire sequence is processed and moved to the "print operation" subroutine in step S8.

[0207] In this embodiment, there is no print data on the seventh page and beyond. Therefore, in step S155, when it is determined that there is no print data on the seventh page and beyond, the process moves to step S156. In step S156, it is determined whether K(2) = 0 and K(3) = 0 are stored in RAM 203. If either is determined to be 1, the preceding and subsequent print media may not overlap due to the curling of print media P. Therefore, the first feed motor 206 does not switch to high-speed drive. Thus, the intermediate roller 15 and feed roller 3 are still driven synchronously with the transfer roller 5 at 7.6 inches / second, and the process moves to step S158.

[0208] Then, in step S158, after the printing media sensor 16 senses the downstream leading edge of the third printing media P in the conveying direction, the rotation amount of the feed roller 3 is controlled. As a result, the conveying of the third printing media P stops when the downstream leading edge of the third printing media P in the conveying direction reaches a position 10 mm before the gap of the conveying roller. Then, in step S159, the subroutine "Feed 2 from the second conveying path" ends.

[0209] In step S160, when it is determined that K(2) = 0 and K(3) = 0 in RAM 203, in step S157, the first feed motor 206 switches to high-speed drive. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / second. After the print media sensor 16 senses the downstream front end of the third print media P in the conveying direction, the rotation amount of the intermediate roller 15 and the feed roller 3 is controlled. As a result, in step S158, the third print media P stops when the downstream front end of the third print media P in the conveying direction is 10 mm before the gap of the conveyor rollers. Then, in step S159, the "feed 2 from the second conveying path" subroutine ends, and processing returns to Figure 12 The entire sequence is processed and moved to the "print operation" subroutine in step S8.

[0210] Reference Figure 15 The "Print Operation" subroutine is described. In step S15, if it is determined that the number of print media P fed from the paper loading unit 11 in a job is not one (N=3 in the current stage), it is determined in step S19 whether a predetermined condition is met (described later). In step S19, if it is determined that the predetermined condition is not met, the process moves to the "Overlap State Removal" subroutine in step S210.

[0211] Reference Figure 18A and Figure 18BThe "overlapping state release" subroutine is described. In step S211, the value of F in RAM 203 is checked. If F = 1 (i.e., if it is determined that printing is being performed on the second side of the printing medium P), then in step S234, it is determined whether the value of P stored in RAM 203 is 0. Since 1 is stored in the current stage, the process moves to step S244.

[0212] In step S244, when it is determined that the image formation operation for the final row of the second printing medium P is complete, in step S245, the second printing medium P is conveyed by the conveyor roller 5 and the discharge roller 10 at a rate of 18 inches / second. In step S246, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the second printing medium P in the conveying direction has passed the ratchet 12, in step S247, the drive of the conveyor motor 205 is stopped. The first feed motor 206 is not driven until the drive of the conveyor motor 205 stops, and thus the third printing medium P remains stopped with its downstream leading edge in the conveying direction 10 mm before the conveyor roller gap. In this way, the overlap between the second and third printing media P is released.

[0213] In step S248, the feed roller 3 is driven at 15 inches / second to bring the leading edge of the third print media P into contact with the gap of the transport roller, and a skew correction operation is performed on the third print media P. In step S249, the third print media P is aligned based on the print data. In other words, by controlling the rotation of the transport roller 5, the third print media P is conveyed to the print start position based on the position of the transport roller 5 according to the print data. Then, in step S250, the first feed motor 206 switches to low-speed drive and rotates the feed roller 3 at 7.6 inches / second.

[0214] Then, the process returns to Figure 15 The process continues with step S173, and the third printing medium P and the second printing medium P are processed from step S173 onwards.

[0215] In step S19, if it is determined that a predetermined condition is met, then in step S20, the value of F in RAM 203 is checked, and if F = 1 (i.e., if it is determined that printing is being performed on the second side of the printing medium P), then in step S172, it is determined whether the value of P stored in RAM 203 is 0. Since 1 is stored in the current stage, the process moves to the "Print Operation 1" subroutine in step S70.

[0216] Reference Figure 16The "Print Operation 1" subroutine is described. In step S71, it is determined whether the image forming operation for the final line of the second print medium P has started. If the image forming operation has started, in step S72, while maintaining the overlapping state, a skew correction operation for the third print medium P is performed by contacting the downstream front end of the third print medium P with the gap of the conveyor rollers in the conveying direction. Then, in step S73, when it is determined that the image forming operation for the final line of the second print medium P is completed, in step S74, while maintaining the overlapping state with the second print medium P, the third print medium P is aligned based on the print data. In other words, by controlling the rotation amount of the conveyor roller 5, the third print medium P is conveyed to the printing start position based on the position of the conveyor roller 5 based on the print data. In step S75, the first feed motor 206 switches to low-speed drive, and in step S76, the "Print Operation 1" subroutine ends, and processing returns to... Figure 15 Step S173 in the “print operation” sequence.

[0217] In step S173, the printing operation on the second side of the third printing medium P begins by ejecting ink from the print head 7 based on the sixth page of print data. Specifically, the printing operation on the second side of the third printing medium P is performed by repeatedly conveying the third printing medium P through the conveyor roller 5 and by moving the carriage 1 and ejecting ink from the print head 7 (ink ejection operation). Then, in step S174, F=1 is stored in RAM 203 to store an indication that a printing operation has been performed on the second side of the printing medium P, and then in step S130, the process moves to the "ejection operation 1" subroutine.

[0218] Reference Figure 17 The "Discharge Operation 1" subroutine is described. In step S121, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the second printing medium P in the conveying direction has passed the ratchet 12, in step S122, the reverse roller 9 is continuously driven forward at 18 inches / second. Then, in step S123, the second printing medium P is discharged to the outside of the device, and in step S124, the "Discharge Operation 1" subroutine ends. Then, the process returns to... Figure 15 In step S175 of the “Print Operation” subroutine, it is determined whether there is print data on the seventh page and beyond. If it is determined that there is no such print data, the process is moved to the “Exhaust Operation 2” subroutine in step S130.

[0219] Reference Figure 17The "Discharge Operation 2" subroutine is described. In step S131, when it is determined, based on the amount of rotation of the conveyor roller 5 since the start of the alignment operation and the length of the sheet, that the upstream end of the third printing medium P in the conveying direction has passed the ratchet 12, in step S132, the reverse roller 9 is continuously driven forward at 18 inches / second. Then, in step S133, the third printing medium P is discharged to the outside of the device, and in step S134, the "Discharge Operation 2" subroutine ends. Then, the process returns to... Figure 15 The "printing operation" subroutine includes step S176, in which the double-sided printing operation ends.

[0220] Figure 21 and Figure 22 This diagram illustrates the operation for overlapping a preceding print medium and a subsequent print medium according to this embodiment. The method for generating... Figures 2 to 11 The operation described herein, in which the front end of the subsequent printing medium overlaps with the rear end of the preceding printing medium.

[0221] Figure 21 and Figure 22 This is an enlarged view of the area between the feed roller gap formed by the feed roller 3 and the feed driven roller 4, and the transfer roller gap formed by the transfer roller 5 and the clamping roller 6. This embodiment will describe the configuration including a print media holding rod for suppressing the lifting of the rear end of the print media P.

[0222] The process of conveying the printing media by the transfer roller 5 and the feed roller 3 will be described sequentially as three states. (Refer to...) Figure 21 ST30 and ST31 describe operations for subsequent print media to follow the first state of the preceding print media. (Refer to...) Figure 22 ST32 and ST33 describe the operation for a second state that allows subsequent printing media to overlap with preceding printing media. (Refer to...) Figure 22 ST34 in the text describes the third state, which involves performing skew correction operations on subsequent printing media while maintaining the overlap state.

[0223] exist Figure 21 In ST30, the feed roller 3 is controlled to convey the subsequent printing medium P, and the printing medium sensor 16 senses the leading edge of the subsequent printing medium P. The interval from the printing medium sensor 16 to a position P1 where the subsequent printing medium P overlaps with the preceding printing medium P is defined as a first interval A1. Within the first interval A1, operation is performed on the leading edge of the subsequent printing medium P to follow the trailing edge of the preceding printing medium P. P1 is determined according to the configuration of the mechanism.

[0224] In the first state, there is a situation where the following operation is stopped in the first segment A1. For example... Figure 21As shown in ST31, when the leading edge of the subsequent printing medium P exceeds the trailing edge of the preceding printing medium P before P1, no operation is performed to make the subsequent printing medium overlap with the preceding printing medium.

[0225] exist Figure 22 In ST32, the interval from P1 to the position P2 where the printing media holding rod 17 is located is defined as the second interval A2. An operation to overlap the subsequent printing media P with the preceding printing media P is performed in the second interval A2.

[0226] In the second state, within the second interval A2, there is a situation where the operation used to cause subsequent printing media to overlap with previous printing media is stopped. For example... Figure 22 As shown in ST33, if the leading edge of the subsequent printing medium P cannot catch up with the trailing edge of the preceding printing medium P in the second interval A2, then the operation to make the subsequent printing medium overlap with the preceding printing medium cannot be performed.

[0227] exist Figure 22 In ST34, the interval from P2 to P3 is defined as the third interval A3. P3 is, for example, the interval in which the subsequent printing medium P... Figure 13 The position of the leading edge at the stop in step S45. The printing media is conveyed while the subsequent printing media P overlaps with the preceding printing media P until the leading edge of the subsequent printing media P reaches P3. In the third interval A3, it is determined whether the subsequent printing media P should contact the gap of the conveyor rollers used for alignment while maintaining the overlapping state. In other words, it is determined whether alignment should be performed after the skew correction operation while maintaining the overlapping state, or after the skew correction operation should be performed after the overlapping state has been removed.

[0228] Figure 23 This is a flowchart illustrating the skew correction operation for subsequent printing media according to this embodiment. A detailed description will follow here. Figure 15 The judgment related to whether the predetermined conditions are met, as described in S19.

[0229] The operation described is used to determine the following: (i) while maintaining the overlap between the preceding print medium P and the subsequent print medium P, a skew correction operation is performed by bringing the leading edge of the subsequent print medium P into contact with the gap of the conveyor rollers; or (ii) after the overlap between the preceding print medium P and the subsequent print medium P is released, a skew correction operation is performed by bringing the leading edge of the subsequent print medium P into contact with the gap of the conveyor rollers.

[0230] In step S301, processing begins. In step S302, it is determined whether the leading edge of the subsequent printing medium P has reached the determination position. Figure 22(P3 in ST34). If the leading edge has not yet reached the judgment position (step S302: No), it is unclear whether the leading edge of the subsequent printing medium P will contact the conveyor roller gap by being conveyed in a predetermined amount. Therefore, it is determined that only the skew correction operation will be performed on the subsequent printing medium (step S303), after which the judgment operation ends (step S304). In other words, after the rear end of the preceding printing medium P passes through the conveyor roller gap, only the subsequent printing medium P is conveyed and the subsequent printing medium P is brought into contact with the conveyor roller gap for skew correction operation, and then only the subsequent printing medium P is aligned.

[0231] On the other hand, if the leading edge of the subsequent printing medium P has reached the judgment position P3 (step S302: Yes), it is determined whether the trailing edge of the preceding printing medium P has passed through the conveyor roller gap (step S305). If it is determined that the trailing edge has passed through the conveyor roller gap (step S305: Yes), the preceding and subsequent printing media do not overlap, and therefore it is determined that only the subsequent printing medium will undergo skew correction operation (step S306). In other words, skew correction operation is performed by only making the subsequent printing medium P contact the conveyor roller gap, and then only the subsequent printing medium P is aligned.

[0232] On the other hand, if it is determined that the rear end of the preceding printing medium P has not yet passed the gap between the conveyor rollers (step S305: No), it is determined whether the overlap between the rear end of the preceding printing medium P and the front end of the subsequent printing medium P is lower than a threshold (step S307). The position of the rear end of the preceding printing medium P is updated as the printing operation on the preceding printing medium P proceeds. The position of the front end of the subsequent printing medium P is the position determined above. In other words, the overlap decreases as the printing operation on the preceding printing medium P proceeds. If it is determined that the overlap is lower than the threshold (step S307: Yes), a determination is made to remove the overlap state and only the subsequent printing medium is skewed (step S308). In other words, after the image formation operation of the preceding printing medium P is completed, the subsequent printing medium P is not conveyed together with the preceding printing medium P. Specifically, the conveyor roller 5, driven by the conveyor motor 205, conveys the preceding printing medium P. However, the feed roller 3 is not driven. As a result, the overlap state is removed. In addition, a skew correction operation is performed by only contacting the subsequent printing medium P with the gap of the conveyor rollers, and then only the subsequent printing medium P is aligned.

[0233] If it is determined that the overlap is at least a threshold (step S307: No), then it is determined whether the subsequent printing medium P will reach the ratchet 12 when aligning the subsequent printing medium P (step S309). If it is determined that the subsequent printing medium P will not reach the ratchet 12 (step S309: No), then a determination is made to release the overlap state and only the subsequent printing medium is skewed (step S310). In other words, after the image formation operation of the preceding printing medium P is completed, the subsequent printing medium P is not conveyed together with the preceding printing medium P. Specifically, the preceding printing medium P is conveyed by the conveyor roller 5 driven by the conveyor motor 205. However, the feed roller 3 is not driven. As a result, the overlap state is released. Furthermore, the skew correction operation is performed by only contacting the gap between the subsequent printing medium P and the conveyor roller, and then only the subsequent printing medium P is aligned.

[0234] If it is determined that the subsequent printing medium P will reach the ratchet 12 (step S309: Yes), then it is determined whether there is a gap between the final line of the preceding printing medium and the line preceding that final line (step S311). If it is determined that there is no gap (step S311: No), then a determination is made to release the overlapping state and only the subsequent printing medium is subjected to skew correction operation (step S312). If it is determined that there is a gap (step S311: Yes), then the subsequent printing medium P is subjected to skew correction operation while maintaining the overlapping state, and then alignment is performed. In other words, after the image formation operation of the preceding printing medium P is completed, the subsequent printing medium P is made to contact the gap of the conveyor rollers while maintaining an overlap with the preceding printing medium P. Specifically, the conveyor roller 5 and the feed roller 3 are rotated by simultaneously driving the first feed motor 206 with the conveyor motor 205. After the skew correction operation, alignment is performed while the subsequent printing medium P remains overlapped on the preceding printing medium P.

[0235] This method determines whether to maintain or remove the overlap between the preceding print media P and the subsequent print media P.

[0236] Figure 24 This is a flowchart illustrating a configuration for calculating the leading edge position after aligning subsequent printing media, according to this embodiment.

[0237] At step S401, processing begins. In step S402, the printable area of ​​the printable media is read. The topmost printable position (i.e., the top margin) is identified, and thus the top margin of the printable area is set as the leading edge position (step S403). Here, the leading edge position is defined as the distance from the gap of the conveyor rollers.

[0238] Then, the initial print data is read (step S404). This identifies the position from the front of the print media to which the initial print data corresponds (detecting non-printing areas), and therefore determines whether the distance from the front of the print media to the initial print data is greater than the set front position (step S405). If the distance from the front of the print media to the initial print data is greater than the set front position (step S405: Yes), the front position is updated to the distance from the front of the print media to the initial print data (step S406). However, if the distance from the front of the print media to the initial print data is not greater than the set front position (step S405: No), the process moves to step S407.

[0239] Next, an initial carriage movement command is generated (step S407). Then, it is determined whether the amount of print media transported for the initial carriage movement is greater than the set leading edge position (step S408). If the amount of print media transported for the initial carriage movement is greater than the set leading edge position (step S408: Yes), the leading edge position is updated to the amount of print media transported for the initial carriage movement (step S409). If the amount of print media transported for the initial carriage movement is not greater than the set leading edge position (step S408: No), the leading edge position is not updated. As described so far, the leading edge position of the subsequent print media P is finally determined (step S410), and then the process ends (step S411). The determination can be based on the finally determined leading edge position ( Figure 23 Step S309) When aligning the subsequent printing medium P, will the subsequent printing medium P reach the ratchet 12?

[0240] As described above, according to the foregoing embodiments, regardless of whether the printing medium is fed from the paper loading unit or from the second transport path, control can be performed to make the front end of the subsequent printing medium overlap with the rear end of the preceding printing medium.

[0241] The foregoing embodiments describe a case where the printing medium P is discharged outside the device by conveying it downstream in the conveying direction using a reversing roller 9 for reversing the conveying direction of the printing medium. However, the same effect can be achieved even when the configuration includes a discharge path for conveying the printing medium P to the outside of the device between the reversing roller 9 and the discharge roller 10, and a switching member for switching the printing medium P between the direction toward the reversing roller 9 and the conveying direction toward the discharge path.

[0242] Other embodiments

[0243] The embodiments of the present invention can also be implemented by providing software (programs) that perform the functions of the above embodiments to a system or device via a network or various storage media, and the computer or central processing unit (CPU) or microprocessor unit (MPU) of the system or device reads out and executes the program.

[0244] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A printing device, comprising: A supply component, configured to supply printing media; A feed roller is configured to convey the printing medium supplied by the supply component; A conveyor roller configured to convey the printing medium conveyed by the feed roller in the conveying direction; A printing unit configured to print an image on a printing medium conveyed by the conveyor roller downstream of the conveyor roller by discharging ink; A carriage configured to move the printing component in a direction intersecting the conveying direction; A reverse path is configured to return the printed medium, which has been printed by the printing unit and has been reversed, to the feed roller; as well as The control unit is capable of: A first control is configured to, between the feed roller and the transfer roller, cause a second printing medium supplied from the supply member to overlap with a first printing medium being printed on a first surface by the printing member, and A second control is used to cause the first printing medium, which has been conveyed from the reverse path and printed on the first surface by the printing component, to overlap with the second printing medium being printed on the first surface by the printing component between the feed roller and the transfer roller.

2. The printing device according to claim 1, wherein, The control unit is capable of performing a third control, which is used to cause a third printing medium supplied from the supply unit to overlap with the first printing medium being printed on a second surface that is the reverse side of the first surface, between the feed roller and the transfer roller.

3. The printing device according to claim 1, further comprising: An ejection path, located downstream of the printing component in the conveying direction, is configured to eject the printed medium containing the printed image. The reversing roller is arranged in the discharge path. The reversing roller discharges the printing medium by rotating in a first direction and conveys the printing medium to be printed by the printing component to the reversing path by rotating in a second direction opposite to the first direction.

4. The printing device according to claim 1, further comprising: A guide section, which is arranged between the feed roller and the transfer roller, and Intermediate rollers, which are arranged in the reverse path, The intermediate roller conveys the printing medium from the reverse path to the guide section.

5. The printing apparatus according to claim 1, further comprising: A sensor is disposed between the feed roller and the transfer roller and is configured to sense the end of the printing medium.

6. The printing device according to claim 1, in, In the second control, the control unit performs a skew correction operation, which is used to bring the first printing medium conveyed from the reverse path into contact with the conveyor roller when the conveyor roller stops.

7. The printing device according to claim 1, in, In the second control, the control component determines, based on the printing data, whether to perform control to overlap the rear end of the first printing medium, which has already been printed on the first surface, with the rear end of the second printing medium.

8. The printing apparatus according to claim 7, in, The printing data is the printing density of the preset printing area.

9. The printing apparatus according to claim 8, in, In the second control, the control component determines whether to perform control to make the rear end of the first printing medium, which has been printed on the first surface, overlap with the rear end of the second printing medium based on the printing data of the preset printing area where the first printing medium and the second printing medium overlap.

10. The printing apparatus according to claim 8, in, In the second control, the control component determines whether to perform control to make the rear end of the first printing medium, which has been printed on the first surface, overlap with the rear end of the second printing medium by comparing the printing density of the preset printing area with a preset printing density.

11. The printing apparatus according to claim 8, in, The preset printing area is a first area at the front end of the printing medium and a second area at the rear end of the printing medium.

12. The printing apparatus according to claim 4, in, In the second control, the control unit sets the conveying speed of the intermediate roller conveying the first printing medium to a speed higher than the speed of the conveying roller while the conveying roller is conveying the second printing medium, so that the first printing medium catches up with the second printing medium.

13. The printing apparatus according to claim 3, in, The control component releases the overlap between the rear end of the first printing medium and the front end of the second printing medium by setting the conveying speed of the reversing roller in the first direction to a speed higher than the speed at which the conveying roller conveys the second printing medium being printed by the printing component.

14. The printing apparatus according to claim 1, in, The control unit detects the leading edge position of the second printing medium before the printing unit performs the final line printing operation on the first printing medium.

15. The printing apparatus according to claim 1, in, If it is determined that the control for making the front end of the second printing medium overlap with the rear end of the first printing medium is skipped, the control unit, while stopping the delivery of the second printing medium, delivers the first printing medium to a position opposite to the printing unit.

16. A method for controlling a printing device, the printing device comprising: A supply component, configured to supply printing media; A feed roller is configured to convey the printing medium supplied by the supply component; A conveyor roller configured to convey the printing medium conveyed by the feed roller in the conveying direction; A printing unit configured to print an image on a printing medium conveyed by the conveyor roller downstream of the conveyor roller by discharging ink; A carriage configured to move the printing component in a direction intersecting the conveying direction; as well as A reverse path, configured to return the printed media, which has been printed and reversed, to the feed roller, and The control method includes performing control, and the control is capable of performing: A first control is configured to, between the feed roller and the transfer roller, cause a second printing medium supplied from the supply member to overlap with a first printing medium being printed on a first surface by the printing member, and A second control is used to cause the first printing medium, which has been conveyed from the reverse path and printed on the first surface by the printing component, to overlap with the second printing medium being printed on the first surface by the printing component between the feed roller and the transfer roller.

17. The control method for the printing device according to claim 16, wherein, A third control is performed in the control, which is used to cause a third printing medium supplied from the supply member to overlap with the first printing medium being printed on a second surface that is the reverse side of the first surface, between the feed roller and the transfer roller.

18. The control method for the printing device according to claim 16, in, The printing apparatus further includes an exhaust path located downstream of the printing component in the transport direction, the exhaust path being configured to exhaust the printed medium containing the image, and A reversing roller is arranged in the discharge path. The reversing roller discharges the printing medium by rotating in a first direction and conveys the printing medium to be printed by the printing component to the reversing path by rotating in a second direction opposite to the first direction.

19. The control method for the printing device according to claim 16, in, The printing apparatus further includes a guide section disposed between the feed roller and the transfer roller, and an intermediate roller disposed in the reverse path, and The intermediate roller conveys the printing medium from the reverse path to the guide section.

20. The control method for the printing device according to claim 16, in, The printing apparatus also includes a sensor disposed between the feed roller and the transfer roller, the sensor being configured to sense the end of the printing medium.

21. The control method for the printing device according to claim 16, in, In the second control, a skew correction operation is performed to bring the first printing medium conveyed from the reverse path into contact with the conveyor roller when the conveyor roller stops.

22. The control method for the printing device according to claim 16, in, In the second control, it is determined whether to perform control to make the rear end of the first printing medium, which has been printed on the first surface, overlap with the rear end of the second printing medium based on the printing data.

23. The control method for the printing device according to claim 22, in, The printing data is the printing density of the preset printing area.

24. The control method for the printing device according to claim 23, in, In the second control, based on the printing data of the preset printing area where the first printing medium and the second printing medium overlap, it is determined whether to perform control to make the rear end of the first printing medium, which has been printed on the first surface, overlap with the rear end of the second printing medium.

25. The control method for the printing device according to claim 23, in, In the second control, the printing density of the preset printing area is compared with the preset printing density to determine whether to perform control to make the rear end of the first printing medium that has been printed on the first surface overlap with the rear end of the second printing medium.

26. A non-transitory computer-readable storage medium storing a program that causes a computer to perform the control method for a printing apparatus according to claim 16.

27. A computer program product comprising a program that causes a computer to perform the control method for a printing apparatus according to claim 16.

Images