Recording device and its control method, program, and storage medium

Abstract

To provide a recording device capable of shortening time until a recording medium is fed to a recording area opposite to a recording head.SOLUTION: A recording device is equipped with a supply portion that supplies a recording medium, a guide portion that guides the recording medium supplied by the supply portion, a carrying portion that carries the recording medium guided by the guide portion in a carrying direction, a recording portion that records an image to the recording medium carried by the carrying portion on the downstream of the carrying portion, and an inversion path that returns the recording medium recorded by the recording portion and inverting its front and back surfaces to the guide portion. The recording device is equipped with a control portion that can perform control for overlapping a tip end portion of a second recording medium on a rear end portion of a first recording medium in the carrying direction, even if, to the first recording medium being recorded by the recording portion, the second recording medium is supplied to the guide portion from either one of the supply portion or the inversion path.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a recording apparatus capable of automatically reversing from the first surface to the second surface of a recording medium and performing double-sided printing.

Background Art

[0002] Patent Document 1 discloses a recording apparatus that sequentially performs control to overlap the leading end in the conveyance direction of a subsequent recording medium to be fed next to a preceding recording medium that has been reversed by a reversing means after printing on the first surface, from a paper loading unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the apparatus described in Patent Document 1, control to overlap a part of the subsequent recording medium with the preceding recording medium is performed only when feeding the recording medium from the paper loading unit. For this reason, there is a technical problem that the subsequent recording medium cannot be continuously overlapped with the preceding recording medium, and it takes time until the recording medium is fed to the recording area facing the recording head.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to provide a recording apparatus capable of shortening the time until a recording medium is fed to a recording area facing a recording head.

Means for Solving the Problems

[0006] The recording apparatus according to the present invention includes supply means for supplying a recording medium, and rollers for conveying the recording medium supplied by the supply means, and the feeding roller, the feedingA conveying roller that conveys the recording medium transported by the roller in the transport direction, and downstream of the conveying roller, the recording medium transported by the conveying roller eject ink A recording means for recording images, A carriage that moves the recording means in a direction intersecting the transport direction, The recording medium recorded by the recording means and with its front and back reversed is the feeding A recording device comprising a reversing path for returning to the roller, wherein the recording means Page 1 The second recording medium supplied from the supply means is placed on the first recording medium on which recording is being performed. feeding A first control that overlaps the roller and the conveying roller, and the recording means Page 1 Records are being kept. Second The recording medium is transported from the reversing path. Furthermore, the first surface recorded by the recording means The 1 The recording medium of the above feeding The system is characterized by having a control means capable of performing a second control that overlaps the roller and the conveying roller. [Effects of the Invention]

[0007] According to the present invention, it is possible to shorten the time it takes to feed the recording medium to the recording area facing the recording head. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view of a key component in a recording device according to one embodiment of the present invention. [Figure 2] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 3] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 4] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 5] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 6] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 7] A diagram illustrating the continuous transmission of overlapping data in a recording device according to one embodiment of the present invention. [Figure 8] A diagram for explaining the stacked continuous feeding in the recording apparatus according to an embodiment of the present invention. [Figure 9] A diagram for explaining the stacked continuous feeding in the recording apparatus according to an embodiment of the present invention. [Figure 10] A diagram for explaining the stacked continuous feeding in the recording apparatus according to an embodiment of the present invention. [Figure 11] A diagram for explaining the stacked continuous feeding in the recording apparatus according to an embodiment of the present invention. [Figure 12] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 13] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 14] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 15] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 16] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 17] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 18] A flowchart of the stacked continuous feeding operation in one embodiment. [Figure 19] A block diagram of the recording apparatus in one embodiment. [Figure 20] A diagram for explaining the configuration of the pickup roller. [Figure 21] A diagram for explaining the operation of stacking a subsequent sheet on a preceding sheet. [Figure 22] A diagram for explaining the operation of stacking a subsequent sheet on a preceding sheet. [Figure 23] A flowchart for explaining the skew correction operation of a subsequent sheet in one embodiment. [Figure 24] A flowchart for explaining the operation of calculating the leading edge position of a subsequent sheet. [Figure 25] A diagram for explaining the recording area on the first surface of the recording medium P in one embodiment. [Figure 26] A diagram for explaining the recording determination state with respect to the first surface of the recording medium P in one embodiment. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] Figure 1 is a cross-sectional view illustrating the main parts of a recording device 200 according to one embodiment of the present invention. The schematic configuration of the recording device 200 in this embodiment will be explained using the diagrams STA to STC in Figure 1.

[0011] In STA in Figure 1, P is a recording medium. Multiple recording media P are stacked in the paper stacking section 11. 2 is a pickup roller that contacts the uppermost recording media P stacked in the paper stacking section 11 to pick it up. 3 is a feed roller that feeds the recording media P picked up by the pickup roller 2 downstream in the transport direction along the first transport path 100. 4 is a feed-driven roller that is biased towards the feed roller 3 and, together with the feed roller 3, grips and feeds the recording media P. The part of the first transport path 100 that guides the recording media P between the feed roller 3 and the transport roller 5 (described later) is referred to as the guide section 100a.

[0012] 5 is a transport roller that transports the recording medium P, which has been fed by the feed roller 3 and the feed-driven roller 4, to a position facing the recording head 7. 6 is a pinch roller that is biased towards the transport roller 5 and, together with the transport roller 5, grips and transports the recording medium P.

[0013] 7 is a recording head that performs recording on the recording medium P conveyed by the transport roller 5 and the pinch roller 6. In this embodiment, the recording head 7 is described as an inkjet recording head that ejects ink to record on the recording medium P. 8 is a platen that supports the second surface (back side) of the recording medium P at a position opposite to the recording head 7. 1 is a carriage that carries the recording head 7 and moves in a direction intersecting the recording medium transport direction.

[0014] 9 is a reversing roller that rotates (forward) in the direction of arrow A in STA in Figure 1 by forward driving the second feed motor 207 (see Figure 19), and is capable of transporting the recording medium P recorded by the recording head 7 in the direction of arrow C. The reversing roller 9 can discharge the recording medium P outside the device as indicated by arrow C. The discharge path 102 is the section that guides the discharge of the recording medium P from the discharge roller 10 (described later) to the downstream side of the reversing roller 9 in the transport direction.

[0015] Furthermore, as shown in the STB in Figure 1, the recording medium P is transported in the direction of arrow C in the STB in Figure 1, and after the upstream end of the recording medium P in the transport direction reaches the vicinity of the reversing roller 9, the second feed motor 207 is driven in reverse. As a result, the reversing roller 9 rotates in the direction of arrow B in the STC in Figure 1 (rotates in the opposite direction), and the recording medium P is flipped over and transported along the guide in the direction of arrow D in the figure within the second transport path (reversing path) 101.

[0016] At this time, the reversal of the reversing roller 9 causes the intermediate roller 15 to also rotate (reverse) in the direction of arrow B in the STC in Figure 1, and transports the recording medium P in the second transport path 101 toward the feed roller 3.

[0017] 10 is an ejection roller that transports the recording medium P, which has been recorded by the recording head 7, toward the reversing roller 9. 12 is a spur that rotates in contact with the recording surface of the recording medium P, which has been recorded by the recording head 7. Here, the spur 12 is biased toward the ejection roller 10. 13 is a reversing driven roller that is biased toward the reversing roller 9 and, together with the reversing roller 9, grips and transports the recording medium P. 14 is an intermediate driven roller that is biased toward the intermediate roller 15 and, together with the intermediate roller 15, grips and transports the recording medium P.

[0018] Between the feeding nip section formed by the feeding roller 3 and the feeding driven roller 4, and the conveying nip section formed by the conveying roller 5 and the pinch roller 6, the recording medium P is guided within the first conveying path 100 by a guide. 16 is a recording medium detection sensor for detecting the leading and trailing ends of the recording medium P. The recording medium detection sensor 16 is located downstream of the feeding roller 3 in the recording medium conveying direction.

[0019] Figure 20 is a diagram illustrating the configuration of the pickup roller 2. As mentioned above, the pickup roller 2 contacts the uppermost recording medium loaded in the paper stacking section 11 to pick up the recording medium. 19 is a drive shaft for transmitting the drive of the first feeding motor 206, which will be described later, to the pickup roller 2. When picking up the recording medium P, the drive shaft 19 and the pickup roller 2 rotate in the direction of arrow E in STA in Figure 1.

[0020] A projection 19a is provided on the drive shaft 19. A recess 2c is formed in the pickup roller 2 into which the projection 19a fits. As shown in Figure 20(a), when the projection 19a is in contact with the first surface 2a of the recess 2c of the pickup roller 2, the drive of the drive shaft 19 is transmitted to the pickup roller 2, and when the drive shaft 19 is driven, the pickup roller 2 also rotates. On the other hand, as shown in Figure 20(b), when the projection 19a is in contact with the second surface 2b of the recess 2c of the pickup roller 2, the drive of the drive shaft 19 is not transmitted to the pickup roller 2, and the pickup roller 2 does not rotate even when the drive shaft 19 is driven. When the projection 19a is not in contact with either the first surface 2a or the second surface 2b, and is between the first surface 2a and the second surface 2b, the pickup roller 2 does not rotate even when the drive shaft 19 is driven.

[0021] Figure 19 is a block diagram of the recording device 200 of this embodiment. 201 is an MPU that controls the operation of each part and data processing. As will be described later, the MPU 201 also functions as a transport control means that can control the transport of recording media so that the rear end of the preceding recording media and the front end of the following recording media overlap. 202 is a ROM that stores programs and data executed by the MPU 201. 203 is a RAM that temporarily stores processing data executed by the MPU 201 and data received from the host computer 214.

[0022] The recording head 7 is controlled by the recording head driver 212. The carriage motor 204 that drives the carriage 1 is controlled by the carriage motor driver 208. The transport roller 5 and the discharge roller 10 are driven by the transport motor 205. The transport motor 205 is controlled by the transport motor driver 209.

[0023] The pickup roller 2, the feed roller 3, and the intermediate roller 15 are driven by the first feed motor 206. The first feed motor 206 is controlled by the first feed motor driver 210. The reversing roller 9 and the intermediate roller 15 are driven by the second feed motor 207.

[0024] At this time, the forward rotation of the first feed motor 206 causes the pickup roller 2 and the feed roller 3 to rotate synchronously, transporting the recording medium P in the direction of the transport roller 5. Furthermore, when the first feed motor 206 is driven in reverse, it operates as follows due to a drive switch (not shown). In the reverse drive state of the first drive switch, only the feed roller 3 rotates, transporting the recording medium P in the direction of the transport roller 5. Then, in the reverse drive state of the second drive switch, the feed roller 3 and the intermediate roller 15 rotate, transporting the recording medium P in the direction of the transport roller 5.

[0025] When the second feed motor 207 is driven in the forward direction, the reversing roller 9 rotates in a direction that discharges the recording medium P outside the device. When the second feed motor 207 is driven in the reverse direction, the reversing roller 9 and the intermediate roller 15 rotate synchronously, transporting the recording medium P in the second transport path 101 in the direction of the feed roller 3.

[0026] The host computer 214 is equipped with a printer driver 2141 for collecting recording information such as the recorded image and the quality of the recorded image, and communicating this information with the recording device 200 when the user commands the execution of a recording operation. The MPU 201 exchanges recorded images and other information with the host computer 214 via the I / F unit 213.

[0027] Using ST1 in Figure 2 to ST29 in Figure 11, the operation of continuous double-sided printing in double-sided printing mode will be explained in chronological order, using an example where six pages of recording data are printed on both sides of three recording media P in one job. When recording data in double-sided printing mode is transmitted from the host computer 214 via the I / F unit 213, it is processed by the MPU 201 and then expanded into the RAM 203. Then, the MPU 201 starts the recording operation based on the expanded data.

[0028] The explanation will be given with reference to ST1 in Figure 2. First, the first feed motor 206 is driven at a low speed in the forward direction by the first feed motor driver 210. As a result, the pickup roller 2 rotates at 7.6 inches / sec. When the pickup roller 2 rotates, the topmost recording medium P loaded in the paper stacking section 11 is picked up. The first recording medium P picked up by the pickup roller 2 is transported by the feed roller 3, which rotates in the same direction as the pickup roller 2, while being guided to the guide section 100a. The feed roller 3 is also driven by the first feed motor 206. This embodiment will be described with a configuration that includes the pickup roller 2 and the feed roller 3. However, a configuration with only the feed roller 3 for feeding the recording medium loaded in the paper stacking section 11 is also possible.

[0029] When the leading edge of the first recording medium P is detected by the recording medium detection sensor 16 located downstream of the feed roller 3 in the transport direction, the first feed motor 206 is switched to high-speed drive while remaining in forward rotation. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec.

[0030] The explanation will be given with reference to ST2 in Figure 2. As the feed roller 3 continues to rotate, the downstream end of the first recording medium P in the transport direction abuts against the transport nip formed by the transport roller 5 and the pinch roller 6. At this time, the transport roller 5 is stopped. By continuing to rotate the feed roller 3 by a predetermined amount even after the downstream end of the first recording medium P in the transport direction abuts against the transport nip, the tip of the first recording medium P is aligned with the transport nip and its skew is corrected. The skew correction operation is also called the register picking operation.

[0031] The explanation will be given with reference to ST3 in Figure 2. Once the skew correction operation of the first recording medium P is completed, the transport motor 205 is driven and the transport roller 5 starts to rotate. The transport roller 5 transports the recording medium at 15 inches / sec. After the first recording medium P is brought to a position facing the recording head 7, ink is ejected from the recording head 7 based on the recording data of the first page, and the recording operation on the first surface of the first recording medium P begins.

[0032] Here, let L be the length of the recording medium P in the transport direction, as shown in Figure 25. When printing on the first side of the recording medium P, the print density of the S region at the leading edge of the transport direction ((1 / 4)L portion) indicated by arrow A is compared with a preset print density. If the print density of the S region falls within the preset print density, S(1)=0 is stored in RAM203; otherwise, S(1)=1 is stored. The number in parentheses indicates the number of prints.

[0033] Furthermore, as the recording operation on the first recording medium P progresses, the print density of the K area at the rear end ((1 / 4)L portion) in the transport direction, indicated by arrow A, is compared with a preset print density. If the print density of the K area falls within the preset print density range, K(1)=0 is stored in RAM203; otherwise, K(1)=1 is stored. Similarly, the number in parentheses indicates the number of printed sheets.

[0034] Furthermore, as shown in Figure 26, if the number of printed pages N on the recording medium P becomes 4 or more, the value of N in S(N) and K(N) is converted to the value of M in the table, and the memory areas of S(M) and K(M) are overwritten accordingly.

[0035] The leading edge operation is performed by first positioning the leading edge of the first recording medium P against the transport nip section, thereby positioning it at the location of the transport roller 5, and then controlling the amount of rotation of the transport roller 5 based on the position of the transport roller 5. If, during the leading edge operation, it is necessary to pick up the second recording medium P from the paper stacking section 11 using the pickup roller 2, the first feed motor 206 is driven in the forward direction, and the pickup roller 2 and the feed roller 3 are also driven in synchronously with the transport roller 5.

[0036] Furthermore, if it is not necessary to pick up the second recording medium P, the first feed motor 206 is driven in reverse in the first drive switching state, and only the feed roller 3 is driven in synchronously with the transport roller 5.

[0037] If there is recording data to be recorded on the second and subsequent recording media P, in this embodiment, the recording media P that will be recorded after the recording operation on the first surface of the first recording media P is the second recording media P picked up from the paper stacking unit 11. The first surface of the second recording media P is set to be recorded after the first surface of the first recording media P. For this reason, the upstream end (rear end) of the first recording media P in the transport direction must pass the pickup roller 2, and the drive shaft 19 must be driven for a predetermined time before the second recording media P is picked up (delayed feeding). For this reason, the first feeding motor 206 is driven in the forward direction.

[0038] The recording device of this embodiment is a serial type recording device in which a recording head 7 is mounted on a carriage 1. The device repeatedly performs a transport operation in which a predetermined amount of recording medium is intermittently transported by transport rollers 5, and an image forming operation in which ink is ejected from the recording head 7 while the carriage 1 equipped with the recording head 7 is moved when the transport rollers 5 are stopped. This operation performs the recording operation on the first recording medium P.

[0039] When the first recording medium P is brought to the front, the first feed motor 206 switches from forward rotation to low-speed drive. That is, the pickup roller 2 and the feed roller 3 rotate at 7.6 inches / sec. When the first recording medium P is being intermittently transported by the transport roller 5 in predetermined amounts, the feed roller 3 is also intermittently driven by the first feed motor 206. That is, when the transport roller 5 is rotating, the feed roller 3 also rotates, and when the transport roller 5 is stopped, the feed roller 3 also stops. The rotation speed of the feed roller 3 is small compared to the rotation speed (transport speed) of the transport roller 5. Therefore, the recording medium P is stretched between the transport roller 5 and the feed roller 3. In other words, the feed roller 3 is rotated along with the first recording medium P being transported by the transport roller 5.

[0040] The drive shaft 19 is also driven in order to intermittently drive the first feed motor 206 in the forward direction. As mentioned above, the rotational speed of the pickup roller 2 is smaller than the rotational speed of the transport roller 5. Therefore, the pickup roller 2 is rotated along with the recording medium P being transported by the transport roller 5. In other words, the pickup roller 2 is in a state of anticipating the drive shaft 19. Specifically, the projection 19a of the drive shaft 19 is separated from the first surface 2a and in contact with the second surface 2b. Therefore, even if the upstream end (rear end) of the first recording medium P in the transport direction passes the pickup roller 2, the second recording medium P is not picked up immediately. After the drive shaft 19 has been driven for a predetermined time, the projection 19a comes into contact with the first surface 2a, and the pickup roller 2 begins to rotate.

[0041] Due to factors such as the responsiveness of the sensor, the recording medium detection sensor 16 requires a predetermined distance between recording media to detect the edges of the recording media P. In other words, after the recording medium detection sensor 16 detects the upstream end (rear end) of the first recording media P in the transport direction, a predetermined time interval is required before detecting the downstream leading end of the second recording media P in the transport direction. To achieve this, a predetermined distance must be maintained between the upstream end of the first recording media P in the transport direction and the downstream leading end of the second recording media P in the transport direction, and the recess 2c of the pickup roller 2 is set to approximately 70 degrees.

[0042] The explanation will be given with reference to ST4 in Figure 3. The second recording medium P, picked up by the pickup roller 2, is transported by the feed roller 3. At this time, the first recording medium P is subjected to image formation by the recording head 7 based on the recorded data. When the leading edge of the second recording medium P is detected by the recording medium detection sensor 16, the first feed motor 206 is switched to high-speed drive while remaining in forward rotation. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec.

[0043] The explanation will be given with reference to ST5 in Figure 3. By moving the second recording medium P at a speed relative to the speed at which the first recording medium P moves downstream due to the recording operation by the recording head 7, a state can be formed in which the downstream end of the second recording medium P in the transport direction overlaps the upstream end of the first recording medium P in the transport direction.

[0044] Since the first recording medium P is performing a recording operation based on the recorded data, the first recording medium P is intermittently transported by the transport roller 5. Meanwhile, after the downstream end of the second recording medium P in the transport direction is detected by the recording medium detection sensor 16, the feed roller 3 is rotated continuously at 20 inches / sec to catch up with the first recording medium P. Subsequently, the second recording medium P is transported by the feed roller 3 until the downstream end in the transport direction stops at a predetermined position upstream of the transport nip. The position of the downstream end of the second recording medium P in the transport direction is calculated from the amount of rotation of the feed roller 3 since the downstream end of the second recording medium P in the transport direction was detected by the recording medium detection sensor 16, and is controlled based on this calculation result. At this time, the first recording medium P is performing an image forming operation by the recording head 7 based on the recorded data.

[0045] The explanation will be given with reference to ST6 in Figure 3. When the transport roller 5 is stopped to perform the image formation operation (ink ejection operation) of the last row of the first recording medium P, the feed roller 3 is driven to bring the leading edge of the second recording medium P against the transport nip and perform the diagonal correction operation of the second recording medium P.

[0046] The explanation will be given with reference to ST7 in Figure 4. When the image formation operation of the last row of the first recording medium P is completed, the transport roller 5 is rotated by a predetermined amount to maintain the state in which the second recording medium P is overlapping the first recording medium P, and the beginning of the second recording medium P can be brought out.

[0047] After the second recording medium P is fed from the paper stacking unit 11 by the pickup roller 2, it is determined whether or not the recording medium P to be cueed was fed from the paper stacking unit 11. If this determination determines that the recording medium P to be cueed was fed from the paper stacking unit 11, the next recording medium P is selected to be supplied from the second transport path 101 to a position facing the recording head 7. In this case, it is determined that the second recording medium P was fed from the paper stacking unit 11, so the next recording medium P to be cueed will be supplied from the second transport path 101 to a position facing the recording head 7. It is also necessary to ensure that the next recording medium P to be cueed is not fed with a delay from the paper stacking unit 11. Furthermore, since the second recording medium P was fed from the paper stacking unit 11, cueing of the second recording medium P is performed by driving the first feed motor 206 in reverse in the first drive switching state. Furthermore, the pickup roller 2 and the intermediate roller 15 are not driven, and the feed roller 3 is controlled to be driven together with the transport roller 5.

[0048] When the second recording medium P is led out, the first feed motor 206 is switched to low-speed drive while remaining in the reverse drive state of the first drive switching state. That is, the feed roller 3 rotates at 7.6 inches / sec. While the transport roller 5 is intermittently transporting the second recording medium P in predetermined amounts, the first feed motor 206 also intermittently drives the feed roller 3. On the second recording medium P, the recording head 7 performs a recording operation based on the recording data.

[0049] At this time, as with the printing on the first surface of the first recording medium P described above, the print density is compared, and if the print density of the S area is within the preset print density range, S(2)=0 is stored in RAM203; otherwise, S(2)=1 is stored. Also, as the recording operation on the second recording medium P progresses, the print density of the K area at the rear end ((1 / 4)L portion) of the second recording medium in the current transport direction is compared with the preset print density (see Figure 25). As a result of this comparison, if the print density of the K area is within the preset print density range, K(2)=0 is stored in RAM203; otherwise, K(2)=1 is stored. When the second recording medium P is intermittently transported for the recording operation, the first recording medium P is also transported intermittently.

[0050] Refer to ST8 in Figure 4 for explanation. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, it is determined that the upstream end of the first recording medium P in the transport direction has passed the spur 12, after which the second feed motor 207 is driven at high speed in the forward direction by the second feed motor driver 211. The reversing roller 9 rotates at 18 inches / sec in the direction of arrow A in Figure 1. As a result, the speed at which the reversing roller 9 transports the first recording medium P is faster than the speed at which the transport roller 5 transports the second recording medium P. Therefore, the overlap between the upstream end of the first recording medium P in the transport direction and the downstream end of the second recording medium P in the transport direction is eliminated. Subsequently, as will be described later, the first recording medium P is reversed by the reversing roller 9 and enters the second transport path 101, and after its upstream rear end in the transport direction has passed the reversing roller 9, the downstream end of the second recording medium P in the transport direction can pass the reversing roller 9. Note that the upstream rear end of the first recording medium P within the second transport path 101 refers to the downstream front end in the first transport path 100 before it is reversed.

[0051] The explanation will be given with reference to ST9 in Figure 4. When the reversing roller 9 rotates in the direction of arrow A in STA in Figure 1, the first recording medium P is transported in the direction of arrow C in STA in Figure 1. As a result, the first recording medium P is continuously transported until its upstream end in the transport direction reaches a predetermined position on the upstream side of the reversing roller 9. Therefore, the upstream end in the transport direction of the first recording medium P and the downstream end in the transport direction of the second recording medium P, which is being transported intermittently by a predetermined amount, are separated.

[0052] The following explanation will be given with reference to ST10 in Figure 5. When the upstream end of the first recording medium P reaches a predetermined position upstream of the reversing roller 9 in the transport direction, the second feed motor driver 211 switches the second feed motor 207 to high-speed drive in reverse. As a result, the reversing roller 9 and the intermediate roller 15 rotate at 18 inches / sec in the direction of arrow B in STC in Figure 1. The first recording medium P is then transported along the guide by the reversing roller 9 and the intermediate roller 15 within the second transport path (reversing path) 101 until its downstream end reaches a predetermined position just before the first transport path 100. This predetermined position is calculated from the amount of rotation of the transport roller 5 from the start of the head-out operation and the length of the paper.

[0053] The following explanation will be given with reference to ST11 in Figure 5. As the transport of the second recording medium P progresses, and the upstream end of the second recording medium P in the transport direction is detected by the recording medium detection sensor 16, the first feed motor driver 210 drives the first feed motor 206 in reverse at a low speed in the second drive switching state. As a result, the intermediate roller 15 and the feed roller 3 rotate at 7.6 inches / sec in the direction of arrow B in the STC in Figure 1. The first recording medium P is then transported by the intermediate roller 15 and the feed roller 3 from the second transport path 101 through the first transport path 100 towards the transport roller 5. At this time, the second recording medium P is undergoing image formation by the recording head 7 based on the recorded data. When the downstream end of the first recording medium P in the transport direction is detected by the recording medium detection sensor 16, the first feed motor 206 is switched to high-speed drive while still in reverse drive in the second drive switching state. That is, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec.

[0054] Before switching the first feed motor 206 to high-speed drive, the values ​​in the RAM 203 described above are checked for the downstream end of the first recording medium P in the transport direction and the upstream end of the second recording medium P in the transport direction. Note that the downstream end of the first recording medium P in the second transport path 101 refers to the upstream end in the first transport path 100 before reversal. In other words, the values ​​of K(1) stored in the RAM 203 when recording to the rear end of the first surface of the first recording medium P and K(2) of the K area of ​​the second recording medium P are checked. If both K(1) and K(2) are 0, the first feed motor 206 is switched to high-speed drive. If either K(1) or K(2) is 1, the first feed motor 206 is not switched to high-speed drive because there is a possibility that the preceding and succeeding recording mediums cannot be stacked due to curling of the recording medium P.

[0055] At this stage, the value of K(2) in the K region of the second recording medium P is the initial value of 0 because image data has not yet been recorded. Therefore, if the value of K(1) is 1, the first feed motor 206 is not switched to high-speed drive, and the downstream end of the first recording medium P in the transport direction is not overlapped with the upstream end of the second recording medium P in the transport direction. The case where the value of K(1) is 0 and the first feed motor 206 is switched to high-speed drive will be explained next.

[0056] By moving the first recording medium P at a high speed relative to the speed at which the second recording medium P moves downstream due to the recording operation by the recording head 7, a state can be formed in which the leading edge of the first recording medium P overlaps the trailing edge of the second recording medium P. Since the second recording medium P is performing a recording operation based on the recorded data, the second recording medium P is intermittently transported by the transport roller 5. On the other hand, after the leading edge of the first recording medium P is detected by the recording medium detection sensor 16, the feed roller 3 and intermediate roller 15 are continuously rotated at 20 inches / sec to catch up with the second recording medium P.

[0057] Subsequently, the first recording medium P is transported by the feed roller 3 until its downstream end in the transport direction stops at a predetermined position upstream of the transport nip. The position of the downstream end of the first recording medium P in the transport direction is calculated from the amount of rotation of the feed roller 3 since the downstream end of the first recording medium P in the transport direction was detected by the recording medium detection sensor 16, and is controlled based on this calculation result. At this time, the second recording medium P is undergoing image formation by the recording head 7 based on the recorded data.

[0058] The explanation will be given with reference to ST12 in Figure 5. When the transport roller 5 is stopped in order to perform the image formation operation (ink ejection operation) of the last row of the second recording medium P, the feed roller 3 is driven to bring the downstream end of the first recording medium P in the transport direction against the transport nip, thereby correcting the skewed position of the first recording medium P.

[0059] The explanation will be given with reference to ST13 in Figure 6. When the image formation operation of the last row of the second recording medium P is completed, the transport roller 5 is rotated by a predetermined amount to maintain the state in which the first recording medium P is overlapping the second recording medium P, and the beginning of the first recording medium P can be brought out.

[0060] As described above, after the second recording medium P is fed from the paper stacking unit 11 by the pickup roller 2, it is determined whether the recording medium P to be cueed has been fed from the paper stacking unit 11. If this determination determines that the recording medium P has been fed from the second transport path 101, it is further determined whether the recorded data on the second side of the recording medium P that was recorded immediately before cueing is the last recorded data in one job. If, as a result, the recording medium P to be cueed is fed from the second transport path 101 and the recorded data on the second side of the recording medium P that was recorded immediately before is determined to be the last recorded data in one job, the control is performed as follows: The next recording medium P after the recording medium P to be cueed is selected to be supplied from the second transport path to a position facing the recording head 7.

[0061] Furthermore, if, as described above, the recording medium P to be cueed is fed from the second transport path 101, and it is determined that the data recorded on the second side of the recording medium P that was immediately recorded is not the last recorded data in a single job, the following control is performed: That is, the next recording medium P to be cueed is selected to be supplied from the paper stacking unit 11 to a position facing the recording head 7.

[0062] In this judgment, it is determined that the first recording medium P is fed from the second transport path 101, and that the data recorded on the second side of the second recording medium P is not the last recorded data in one job. Therefore, the recording medium P following the first recording medium P that is being cueed will be supplied from the paper stacking unit 11 to a position facing the recording head 7. It is also necessary to ensure that the recording medium P following the first recording medium P that is being cueed is not fed with a delay from the paper stacking unit 11. Furthermore, the first recording medium P is being fed from the second transport path 101. Therefore, to cue the first recording medium P, the first feed motor 206 is driven in reverse in the second drive switching state, and the drive is not transmitted to the pickup roller 2, so that the feed roller 3 and the intermediate roller 15 are driven together with the transport roller 5.

[0063] The intermediate roller 15 and intermediate driven roller 14 are positioned such that, when the first recording medium P is brought forward, the upstream end of the first recording medium P in the transport direction passes through the nip of the intermediate roller 15.

[0064] Next, the first feed motor 206 starts low-speed driving in forward rotation in the first drive switching state. That is, the pickup roller 2 and intermediate roller 3 rotate at 7.6 inches / sec. While the transport roller 5 intermittently transports the first recording medium P in predetermined amounts, the first feed motor 206 also intermittently drives the pickup roller 2 and feed roller 3. A recording operation is performed on the first recording medium P by the recording head 7 based on the recording data. When the first recording medium P is intermittently transported for the recording operation, the third recording medium P, picked up from the paper stacking section 11 by the pickup roller 2, is also intermittently transported.

[0065] The explanation will be given with reference to ST14 in Figure 6. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, it is determined that the upstream end of the second recording medium P in the transport direction has passed the spur 12, after which the second feed motor 207 is driven at high speed in the forward direction by the second feed motor driver 211. The reversing roller 9 rotates at 18 inches / sec in the direction of arrow A in Figure 1. As a result, the speed at which the reversing roller 9 transports the second recording medium P is faster than the speed at which the transport roller 5 transports the first recording medium P. Therefore, the overlap between the upstream end of the second recording medium P in the transport direction and the downstream end of the first recording medium P in the transport direction is eliminated. After that, the second recording medium P is reversed by the reversing roller 9 and enters the second transport path 101, and after its upstream rear end in the transport direction has passed the reversing roller 9, the downstream end of the first recording medium P in the transport direction is able to pass the reversing roller 9. Note that the upstream rear end of the second recording medium P within the second transport path 101 refers to the downstream front end of the first transport path 100 before it is reversed.

[0066] The explanation will be given with reference to ST15 in Figure 6. When the reversing roller 9 rotates in the direction of arrow A in STA in Figure 1, the second recording medium P is transported in the direction of arrow C in STA in Figure 1. As a result, the second recording medium P is continuously transported until its upstream end in the transport direction reaches a predetermined position on the upstream side of the reversing roller 9. Therefore, the upstream end in the transport direction of the second recording medium P and the downstream end in the transport direction of the first recording medium P, which is being transported intermittently by a predetermined amount, are separated.

[0067] When the upstream end of the second recording medium P reaches a predetermined position upstream of the reversing roller 9 in the transport direction, the second feed motor driver 211 switches the second feed motor 207 to high-speed drive in reverse. As a result, the reversing roller 9 and the intermediate roller 15 rotate at 18 inches / sec in the direction of arrow B in the STC in Figure 1. The second recording medium P is then transported along the guide by the reversing roller 9 and the intermediate roller 15 within the second transport path (reversing path) 101 until its downstream end reaches a predetermined position just before the first transport path 100. This predetermined position is calculated from the amount of rotation of the transport roller 5 from the start of the leading-out operation and the length of the paper.

[0068] The explanation will be given with reference to ST16 in Figure 7. The third recording medium P, picked up from the paper stacking section 11 by the pickup roller 2, is transported by the feed roller 3. At this time, the first recording medium P is subjected to image formation by the recording head 7 based on the recorded data. When the leading edge of the third recording medium P is detected by the recording medium detection sensor 16, the first feed motor 206 is switched to high-speed drive while remaining in forward rotation. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec.

[0069] At this time, as with the operation described above, before switching the first feed motor 206 to high-speed drive, the values ​​in the RAM 203 described above are checked for the upstream end in the transport direction of the preceding recording medium P and the downstream end in the transport direction of the succeeding recording medium P. That is, the values ​​of S(1) stored in the RAM 203 when recording to the first front end of the first surface of the first recording medium P and S(3) of the S area of ​​the third recording medium P are checked. Note that the S area of ​​the front end when recording to the first surface of the first recording medium P becomes the upstream end (rear end) in the transport direction of the first recording medium P when it is inverted and supplied to the recording position via the second transport path 101. If both S(1) and S(3) are 0, the first feed motor 206 is switched to high-speed drive. If either S(1) or S(3) is 1, the first feed motor 206 is not switched to high-speed drive because it may not be possible to stack the preceding and succeeding recording mediums due to curling of the recording medium P. At this stage, the value of S(3) in the S area of ​​the third recording medium P is the initial value of 0 because image data has not yet been recorded. If the value of S(1) is 1, the first feed motor 206 is not switched to high-speed drive, and the downstream end of the third recording medium P in the transport direction is not overlapped with the upstream end of the first recording medium P in the transport direction. The case where the value of S(1) is 0 and the first feed motor 206 is switched to high-speed drive will be explained next.

[0070] The following explanation will be given with reference to ST17 in Figure 7. By moving the third recording medium P at a high speed relative to the speed at which the first recording medium P moves downstream due to the recording operation by the recording head 7, a state can be formed in which the leading edge of the third recording medium P overlaps the trailing edge of the first recording medium P. Since the first recording medium P is being recorded based on the recorded data, it is intermittently transported by the transport roller 5. On the other hand, after the leading edge of the third recording medium P is detected by the recording medium detection sensor 16, the feed roller 3 is rotated continuously at 20 inches / sec to catch up with the first recording medium P. After that, the third recording medium P is transported by the feed roller 3 until its downstream leading edge in the transport direction stops at a predetermined position upstream of the transport nip. The position of the downstream leading edge of the third recording medium P in the transport direction is calculated from the amount of rotation of the feed roller 3 after the downstream leading edge of the third recording medium P in the transport direction is detected by the recording medium detection sensor 16, and is controlled based on this calculation result. At this time, the first recording medium P is subjected to image formation by the recording head 7 based on the recorded data.

[0071] The explanation will be given with reference to ST18 in Figure 7. When the transport roller 5 is stopped to perform the image formation operation (ink ejection operation) of the last row of the first recording medium P, the feed roller 3 is driven to bring the leading edge of the third recording medium P against the transport nip, thereby correcting the skew of the third recording medium P.

[0072] The explanation will be given with reference to ST19 in Figure 8. When the image formation operation of the last row of the first recording medium P is completed, the transport roller 5 is rotated by a predetermined amount to maintain the state in which the third recording medium P is overlapping the first recording medium P, and the beginning of the third recording medium P can be brought out.

[0073] As mentioned above, after the second recording medium P is fed from the paper stacking unit 11 by the pickup roller 2, it is determined whether or not the recording medium P to be cueed has been fed from the paper stacking unit 11. If this determination determines that the recording medium P has been fed from the paper stacking unit 11, the next recording medium P after the one to be cueed is selected to be supplied from the second transport path 101 to a position facing the recording head 7. In this case, it is determined that the third recording medium P has been fed from the paper stacking unit 11, so the next recording medium P after the third recording medium P to be cueed will be supplied from the second transport path 101 to a position facing the recording head 7. It is also necessary to ensure that the next recording medium P after the third recording medium P to be cueed is not fed with a delay from the paper stacking unit 11. The third recording medium P has been fed from the paper stacking unit 11. Therefore, when cueing the third recording medium P, the first feed motor 206 is driven in reverse in the first drive switching state, and the drive force is not transmitted to the pickup roller 2 and the intermediate roller 15, and the feed roller 3 is controlled to be driven together with the transport roller 5.

[0074] When the third recording medium P is brought forward, the first feed motor 206 is switched to low-speed drive while remaining in the reverse drive state of the first drive switching state. That is, the feed roller 3 rotates at 7.6 inches / sec. While the transport roller 5 is intermittently transporting the third recording medium P in predetermined amounts, the feed roller 3 is also intermittently driven by the first feed motor 206. On the third recording medium P, the recording head 7 performs a recording operation based on the recording data. At this time, as with the printing on the first surface of the second recording medium P described above, the print density is compared, and if the print density of the S area is within the preset print density, S(3)=0 is stored in the RAM 203, and if it is not, S(3)=1 is stored. Furthermore, as the recording operation on the third recording medium P progresses, the print density of the K area of ​​the rear end ((1 / 4)L portion) of the third recording medium in the transport direction at this stage is compared with the preset print density. Then, as a result of the comparison, if the print density of the K area is within the preset print density range, K(3)=0 is stored in RAM203; otherwise, K(3)=1 is stored. When the third recording medium P is intermittently transported for recording, the first recording medium P is also intermittently transported.

[0075] The explanation will be given with reference to ST20 in Figure 8. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, it is determined that the upstream end of the first recording medium P in the transport direction has passed the spur 12, and then the second feed motor 207 is driven at high speed in the forward direction by the second feed motor driver 211. The reversing roller 9 rotates at 18 inches / sec in the direction of arrow A in Figure 1. As a result, the speed at which the reversing roller 9 transports the first recording medium P is faster than the speed at which the transport roller 5 transports the third recording medium P. Therefore, there is no overlap between the upstream end of the first recording medium P in the transport direction and the downstream end of the third recording medium P in the transport direction.

[0076] The explanation will be given with reference to ST21 in Figure 8. When the reversing roller 9 rotates in the direction of arrow A in STA in Figure 1, the first recording medium P is transported in the direction of arrow C in STA in Figure 1. Recording on the first and second sides of the first recording medium P has been completed. Therefore, the rotation of the reversing roller 9 at 18 inches / sec in the direction of arrow A in STA in Figure 1 causes the first recording medium P to be discharged from the device. In addition, the upstream end of the first recording medium P in the transport direction and the downstream end of the third recording medium P, which is being transported intermittently in predetermined amounts, are separated.

[0077] The following explanation will be given with reference to ST22 and ST23 in Figure 9. As the transport of the third recording medium P progresses, the upstream end of the third recording medium P in the transport direction reaches the position where feeding by the intermediate roller 15 from the second transport path 101 of the second recording medium P begins. At this point, the first feeding motor driver 210 drives the first feeding motor 206 in reverse at a low speed in the second drive switching state. As a result, the intermediate roller 15 and the feeding roller 3 rotate at 7.6 inches / sec in the direction of arrow B in the STC in Figure 1. The second recording medium P is then transported by the intermediate roller 15 and the feeding roller 3 from the second transport path 101 through the first transport path 100 towards the transport roller 5. At this time, the third recording medium P is undergoing image formation by the recording head 7 based on the recorded data. When the recording medium detection sensor 16 detects the downstream end of the second recording medium P in the transport direction, the first feeding motor 206 is switched to high-speed drive while remaining in reverse drive in the second drive switching state. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec.

[0078] At this time, as with the operation described above, before switching the first feed motor 206 to high-speed drive, the values ​​in the RAM 203 described above are checked for the upstream end of the preceding recording medium P in the transport direction and the downstream end of the succeeding recording medium P in the transport direction. Specifically, the value of K(3) in the K region of the upstream end of the third recording medium P and the value of K(2) of the downstream end stored in the RAM 203 when recording to the rear end of the first surface of the second recording medium P are checked. Note that the downstream end of the second recording medium P in the second transport path 101 refers to the upstream rear end in the first transport path 100 before it is reversed. If both K(3) and K(2) are 0, the first feed motor 206 is switched to high-speed drive. If either K(3) or K(2) is 1, the first feed motor 206 is not switched to high-speed drive because it may not be possible to stack the preceding and succeeding recording mediums due to curling of the recording medium P. At this stage, the value of K(3) in the K region of the third recording medium P is the initial value of 0 because image data has not yet been recorded. Therefore, if the value of K(2) is 1, the first feed motor 206 is not switched to high-speed drive, and the downstream end of the second recording medium P in the transport direction is not overlapped with the upstream end of the third recording medium P in the transport direction. The case where the value of K(2) is 0 and the first feed motor 206 is switched to high-speed drive will be explained next.

[0079] By moving the second recording medium P at a high speed relative to the speed at which the third recording medium P moves downstream due to the recording operation by the recording head 7, a state can be formed where the leading edge of the second recording medium P overlaps the trailing edge of the third recording medium P. Since the third recording medium P is performing a recording operation based on the recorded data, the third recording medium P is intermittently transported by the transport roller 5. On the other hand, after the leading edge of the second recording medium P is detected by the recording medium detection sensor 16, the feed roller 3 and intermediate roller 15 are rotated continuously at 20 inches / sec to catch up with the third recording medium P. After that, the second recording medium P is transported by the feed roller 3 until its downstream leading edge in the transport direction stops at a predetermined position upstream of the transport nip. The position of the leading edge of the second recording medium P is calculated from the amount of rotation of the feed roller 3 since the leading edge of the second recording medium P was detected by the recording medium detection sensor 16, and is controlled based on this calculation result. At this time, the third recording medium P is undergoing an image formation operation by the recording head 7 based on the recorded data.

[0080] The explanation will be given with reference to ST24 in Figure 9. When the transport roller 5 is stopped in order to perform the image formation operation (ink ejection operation) of the last row of the third recording medium P, the feed roller 3 is driven to abut the downstream end of the second recording medium P against the transport nip, thereby correcting the skew of the second recording medium P.

[0081] The explanation will be given with reference to ST25 in Figure 10. When the image formation operation of the last row of the third recording medium P is completed, the transport roller 5 is rotated by a predetermined amount to maintain the state in which the second recording medium P is overlapping the third recording medium P, and the beginning of the second recording medium P can be brought out.

[0082] As described above, after the second recording medium P is fed from the paper stacking unit 11 by the pickup roller 2, it is determined whether the recording medium P to be cueed has been fed from the paper stacking unit 11. If this determination determines that the recording medium P has been fed from the second transport path 101, it is further determined whether the recorded data on the second side of the recording medium P that was immediately recorded is the last recorded data in one job. If the recording medium P to be cueed is fed from the second transport path 101 and the recorded data on the second side of the recording medium P that was immediately recorded is determined to be the last recorded data in one job, the control is performed as follows: That is, the next recording medium P after the recording medium P to be cueed is selected to be supplied from the second transport path to a position facing the recording head 7. Also, if the above determination determines that the recording medium P to be cueed is fed from the second transport path 101 and the recorded data on the second side of the recording medium P that was immediately recorded is not the last recorded data in one job, the control is performed as follows. In other words, the next recording medium P after the one being cueed is selected to be supplied from the paper stacking unit 11 to a position facing the recording head 7.

[0083] In this judgment, it is determined that the second recording medium P is fed from the second transport path 101, and that the data recorded on the second side of the third recording medium P is the last recorded data in one job. Therefore, the recording medium P following the second recording medium P that is being cueed will be supplied from the second transport path 101 to a position facing the recording head 7. It is also necessary to ensure that the recording medium P following the second recording medium P that is being cueed is not fed with a delay from the paper stacking unit 11. Furthermore, the second recording medium P is being fed from the second transport path 101. Therefore, to cue the second recording medium P, the first feed motor 206 is driven in reverse in the second drive switching state, and the drive is not transmitted to the pickup roller 2, and the feed roller 3 and intermediate roller 15 are controlled to be driven together with the transport roller 5.

[0084] When the second recording medium P is brought forward, the first feed motor 206 is switched to low-speed drive while remaining in the reverse drive state of the second drive switching state. That is, the feed roller 3 and the intermediate roller rotate at 7.6 inches / sec. The transport roller 5 intermittently transports the second recording medium P in predetermined amounts. A recording operation is performed on the second recording medium P by the recording head 7 based on the recording data. When the second recording medium P is intermittently transported for the recording operation, the third recording medium P is also transported intermittently.

[0085] The explanation will be given with reference to ST26 in Figure 10. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, it is determined that the upstream end of the third recording medium P in the transport direction has passed the spur 12, and then the second feed motor 207 is driven at high speed in the forward direction by the second feed motor driver 211. The reversing roller 9 rotates at 18 inches / sec in the direction of arrow A in Figure 1. As a result, the speed at which the third recording medium P is transported by the reversing roller 9 is faster than the speed at which the second recording medium P is transported by the transport roller 5. Therefore, the overlap between the upstream end of the third recording medium P in the transport direction and the downstream end of the second recording medium P in the transport direction is eliminated. After that, the third recording medium P is reversed by the reversing roller 9 and enters the second transport path 101, and after its upstream rear end in the transport direction has passed the reversing roller 9, the downstream end of the second recording medium P in the transport direction is able to pass the reversing roller 9. Note that the upstream rear end of the second transport path 101 of the third recording medium P refers to the downstream front end of the first transport path 100 before it is reversed.

[0086] When the reversing roller 9 rotates in the direction of arrow A in STA in Figure 1, the third recording medium P is transported in the direction of arrow C in STA in Figure 1. As a result, the third recording medium P is continuously transported until its upstream end in the transport direction reaches a predetermined position on the upstream side of the reversing roller 9. Therefore, the upstream end in the transport direction of the third recording medium P and the downstream end in the transport direction of the second recording medium P, which is being transported intermittently by a predetermined amount, are separated.

[0087] The following explanation will be given with reference to ST27 in Figure 10. When the upstream end of the third recording medium P in the transport direction reaches a predetermined position upstream of the reversing roller 9 in the transport direction, the second feed motor driver 211 switches the second feed motor 207 to high-speed drive in reverse. As a result, the reversing roller 9 and the intermediate roller 15 rotate at 18 inches / sec in the direction of arrow B in the STC in Figure 1. The third recording medium P is then transported along the guide by the reversing roller 9 and the intermediate roller 15 within the second transport path (reversing path) 101 until its downstream end in the transport direction reaches a predetermined position just before the first transport path 100. This predetermined position is also calculated from the amount of rotation of the transport roller 5 from the start of the head-out operation and the length of the paper.

[0088] The explanation will be given with reference to ST28 in Figure 11. As the transport of the second recording medium P progresses, the upstream end of the second recording medium P in the transport direction reaches the position where feeding by the intermediate roller 15 from the second transport path 101 of the third recording medium P, as described later, begins. At this point, the first feeding motor driver 210 drives the first feeding motor 206 in reverse at a low speed in the second drive switching state. As a result, the intermediate roller 15 and the feeding roller 3 rotate at 7.6 inches / sec in the direction of arrow B in the STC in Figure 1. The third recording medium P is then transported by the intermediate roller 15 and the feeding roller 3 from the second transport path 101 through the first transport path 100 towards the transport roller 5. At this time, the second recording medium P is undergoing image formation by the recording head 7 based on the recorded data. When the recording medium detection sensor 16 detects the downstream end of the third recording medium P in the transport direction, the first feeding motor 206 is switched to high-speed drive while still in reverse drive in the second drive switching state. In other words, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec.

[0089] At this time, as in the situation described above, before switching the first feed motor 206 to high-speed drive, the values ​​in RAM 203 described above are checked at the upstream end of the preceding recording medium P in the transport direction and the downstream end of the succeeding recording medium P in the transport direction. Specifically, the values ​​of S(2) stored in RAM 203 when recording to the first front end of the first surface of the second recording medium P and K(3) stored in RAM 203 when recording to the first rear end of the first surface of the third recording medium P are checked. Note that the downstream end of the third recording medium P in the second transport path 101 refers to 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 is switched to high-speed drive. If either S(2) or K(3) is 1, there is a possibility that the preceding and succeeding recording mediums cannot be stacked due to curling of the recording medium P. Therefore, the first feed motor 206 is not switched to high-speed drive. We will now continue explaining 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.

[0090] By moving the third recording medium P at a speed relative to the speed at which the second recording medium P moves downstream due to the recording operation by the recording head 7, a state can be formed in which the leading edge of the third recording medium P overlaps the trailing edge of the second recording medium P. Since the second recording medium P is performing a recording operation based on the recorded data, the second recording medium P is intermittently transported by the transport roller 5. On the other hand, after the leading edge of the third recording medium P is detected by the recording medium detection sensor 16, the feed roller 3 and intermediate roller 15 are rotated continuously at 20 inches / sec to catch up with the second recording medium P. After that, the third recording medium P is transported by the feed roller 3 until the leading edge on the downstream side in the transport direction stops at a predetermined position upstream of the transport nip. The position of the leading edge on the downstream side in the transport direction of the third recording medium P is calculated from the amount of rotation of the feed roller 3 since the leading edge on the downstream side in the transport direction of the third recording medium P was detected by the recording medium detection sensor 16, and is controlled based on this calculation result. At this time, the second recording medium P is performing an image formation operation by the recording head 7 based on the recorded data.

[0091] The explanation will be given with reference to ST29 in Figure 11. When the transport roller 5 is stopped to perform the image formation operation (ink ejection operation) of the last row of the second recording medium P, the feed roller 3 is driven to bring the downstream end of the third recording medium P into contact with the transport nip, thereby correcting the skewed position of the third recording medium P. When the image formation operation of the last row of the second recording medium P is completed, the transport roller 5 is rotated by a predetermined amount to maintain the state in which the third recording medium P is overlapping the second recording medium P, and the beginning of the third recording medium P can be brought forward.

[0092] Once the diagonal correction operation of the third recording medium P is completed, the transport motor 205 is driven, causing the transport roller 5 to start rotating. The transport roller 5 transports the recording medium at 15 inches / sec. After the third recording medium P is brought to a position facing the recording head 7, the recording data for the sixth page is recorded by ejecting ink from the recording head 7 based on the recorded data.

[0093] Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, it is determined that the upstream end of the second recording medium P in the transport direction has passed the spur 12. After this, the second feed motor 207 is driven at high speed in the forward direction by the second feed motor driver 211. The reversing roller 9 rotates at 18 inches / sec in the direction of arrow A in STA in Figure 1. As a result, the speed at which the reversing roller 9 transports the second recording medium P is faster than the speed at which the transport roller 5 transports the third recording medium P. Therefore, there is no overlap between the upstream end of the second recording medium P in the transport direction and the downstream end of the third recording medium P in the transport direction. Since recording on the first and second sides of the second recording medium P is completed, the rotation of the reversing roller 9 at 18 inches / sec in the direction of arrow A in STA in Figure 1 causes the second recording medium P to be ejected from the device.

[0094] When the image formation operation for the last row of the third recording medium P is completed, it means that the recording of the first and second sides of the third recording medium P, which is the last recording medium in a job, is finished. Therefore, the reversing roller 9 is rotated at 18 inches / sec in the direction of arrow A in STA in Figure 1. The discharge roller 10 and the transport roller 5 also rotate at 18 inches / sec in the same direction as the reversing roller 9, thereby discharging the third recording medium P from the device and completing double-sided printing.

[0095] Figures 12 to 18 are flowcharts of the overlapping continuous feeding operation in the double-sided printing mode of this embodiment. The case in which six pages of recording data are recorded on the first side of three recording media P, where the recording operation is performed first, and on the second side, which is the back of the first side.

[0096] In step S1 of Figure 12, when recording data in duplex printing mode is transmitted from the host computer 214 via the I / F unit 213, the recording operation in duplex printing mode starts.

[0097] In step S2, N=1 is stored in RAM 203 as an initial value for managing how many sheets of recording medium P were fed from the paper stacking unit 11 within one job. In step S3, F=0 is stored in RAM 203 as an initial value for managing whether the recording was made on the first or second side of the recording medium P. Note that F=0 represents recording on the first side, and F=1 represents recording on the second side. In step S4, P=0 is stored in RAM 203 as an initial value for managing whether the feeding operation of the recording medium P to the position facing the recording head 7 was initiated from the paper stacking unit 11 or the second transport path 101. Note that P=0 represents feeding from the paper stacking unit 11, and P=1 represents feeding from the second transport path 101.

[0098] In step S5, if it is determined that the number of recording media P to be fed from the paper stacking unit 11 within one job is the first, the process proceeds to the "Feeding from paper stacking unit 1" subroutine shown in step S30 of Figure 13.

[0099] In step S31, the feeding operation of the first recording medium P is started from the paper stacking unit 11. Specifically, the feed motor 206 is driven at a low speed in the forward direction. The pickup roller 2 rotates at 7.6 inches / sec. As a result, the pickup roller 2 picks up the first recording medium P and the feed roller 3 feeds it toward the recording head 7.

[0100] In step S32, the RAM 203 stores P=0 to remember that the recording medium P has been fed from the paper stacking unit 11. In step S33, when the recording medium detection sensor 16 detects the downstream leading edge in the transport direction of the first recording medium P, the feed motor 206 is switched to high-speed drive in step S34. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the feed roller 3 is controlled after the recording medium detection sensor 16 detects the downstream leading edge in the transport direction of the first recording medium P. As a result, in step S35, the downstream leading edge in the transport direction of the first recording medium P is brought into contact with the transport nip section to correct the skew of the first recording medium P.

[0101] In step S36, the first recording medium P is positioned based on the recorded data. That is, by controlling the rotation amount of the transport roller 5, the first recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. In step S37, the feed motor 206 is switched to low-speed drive. As a result, the pickup roller 2 and the feed roller 3 rotate at 7.6 inches / sec. In step S38, the "Feed from paper stacking unit 1" subroutine is terminated, and the program moves to the "Printing operation" subroutine in step S8 of Figure 12.

[0102] The "printing operation" subroutine will be explained with reference to Figure 15. In step S15, if it is determined that the number of recording media P fed from the paper stacking unit 11 in one job is one, then in step S16, the recording operation is started by ejecting ink from the recording head 7 to the first surface of the first recording media P based on the recording data for the first page. Specifically, the transport operation, in which the transport roller 5 intermittently transports the first recording media P, and the image forming operation (ink ejection operation), in which the carriage 1 is moved and ink is ejected from the recording head 7, are repeated. This performs the recording operation on the first surface of the first recording media P.

[0103] The first feed motor 206 is driven intermittently at a low speed in synchronization with the intermittent transport of the first recording medium P by the transport roller 5. That is, the pickup roller 2 and the feed roller 3 rotate intermittently at 7.6 inches / sec.

[0104] Here, the length of the recording medium P in the transport direction is denoted as L, as shown in Figure 25. Then, the print density of the S region at the leading edge of the transport direction ((1 / 4)L portion) indicated by arrow A on the first recording medium P is compared with a preset print density. As a result of this comparison, if the print density of the S region falls within the preset print density, S(1)=0 is stored in RAM203; otherwise, S(1)=1 is stored. The number in parentheses indicates the number of printed sheets.

[0105] Furthermore, as the recording operation on the first recording medium P progresses, the print density of the K area at the current position of the trailing end ((1 / 4)L portion) of the first recording medium in the transport direction, indicated by arrow A, is compared with a preset print density. If the print density of the K area falls within the preset print density range, K(1)=0 is stored in RAM203; otherwise, K(1)=1 is stored. Similarly, the number in parentheses indicates the number of printed sheets.

[0106] Furthermore, as shown in Figure 26, if the number of printed pages N on the recording medium P is 4 or more, the value of N in S(N) and K(N) is converted to the value of M in the table, and the storage areas of S(M) and K(M) are overwritten accordingly.

[0107] In step S17, it is determined whether there is recorded data on the second page. If it is determined that there is no recorded data on the second page, in step S130, the process proceeds to the "Discharge Operation 2" subroutine in Figure 17.

[0108] In step S131, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end in the transport direction of the first recording medium P has passed the spur 12, then in step S132 the reversing roller 9 is driven continuously at 18 inches / sec in the forward direction. Then, in step S133 the first recording medium P is ejected from the device, and in step S134 the "Ejection Operation 2" subroutine is terminated. After that, in step S176 in Figure 15, the double-sided printing is terminated.

[0109] If it is determined in step S17 that there is recording data for the second page, then in step S18, F=0 is stored in RAM203 to remember that a recording operation was performed on the first surface of the recording medium P, and in step S40, the process moves to the "Paper feeding from paper stacking unit 2" subroutine in Figure 13.

[0110] In step S41, the upstream end of the first recording medium P passes the pickup roller 2, and after the drive shaft 19 is driven for a predetermined time, the second recording medium P is picked up. Specifically, the second recording medium P is picked up (delayed feeding) from the paper stacking unit 11 at 7.6 inches / sec by the pickup roller 2. In step S42, P=0 is stored in the RAM 203 to remember that the second recording medium P has been fed from the paper stacking unit 11.

[0111] In step S43, when the recording medium detection sensor 16 detects the downstream leading edge of the second recording medium P in the transport direction, the feed motor 206 is switched to high-speed drive in step S44. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the feed roller 3 is controlled after the recording medium detection sensor 16 detects the downstream leading edge of the second recording medium P in the transport direction. As a result, in step S45, the second recording medium P stops with its downstream leading edge in the transport direction 10 mm in front of the transport nip. Then, in step S46, to remember that the second recording medium P was fed from the paper stacking unit 11 in one job, N=2 is stored in RAM 203 by adding 1 to N. In step S47, the "Feed paper from paper stacking unit 2" subroutine is terminated and the process moves to step S19 in Figure 15.

[0112] In step S19, it is determined whether predetermined conditions are met for overlapping the downstream end of the subsequent recording medium P with the upstream end of the preceding recording medium P in the transport direction. The predetermined conditions will be described later. If it is determined in step S19 that the predetermined conditions are not met, the process proceeds to the "overlapping state release" subroutine in step S210.

[0113] The "Release Overlap State" subroutine will be explained with reference to Figure 18. In step S211, the value of F in RAM 203 is checked, and if F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S212 it is determined whether the value of P stored in RAM 203 is 0. In this case, since 0 is stored in step S42, the process proceeds to step S213. In step S213 it is determined that the image formation operation of the last row of the first recording medium P has been completed, and in step S214 the transport roller 5 and the discharge roller 10 transport the first recording medium P at 18 inches / sec.

[0114] In step S215, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end in the transport direction of the first recording medium P has passed the spur 12, the drive of the transport motor 205 is stopped in step S216. Since the feed motor 206 is not driven until the drive of the transport motor 205 is stopped, the downstream end of the second recording medium P remains stopped at a position 10 mm before the transport nip in the transport direction. This eliminates the overlapping state of the first and second recording medium P. Furthermore, in step S217, the reversing roller 9 is continuously driven in the forward direction at 18 inches / sec, so that the first recording medium P continues to be transported until its upstream end in the transport direction reaches a position 5 mm upstream of the nip of the reversing roller 9 in the transport direction.

[0115] In step S218, the feed roller 3 is driven at 15 inches / sec to bring the leading edge of the second recording medium P into contact with the transport nip, correcting the skew of the second recording medium P, and in step S219, the second recording medium P is positioned based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the second recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. Then, in step S220, the feed motor 206 is switched to low-speed drive, and the feed roller 3 is rotated at 7.6 inches / sec.

[0116] In step S221, the reversing roller 9 and intermediate roller 15 are continuously driven in reverse at 18 inches / sec. As a result, the first recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and intermediate roller 15. Then, in step S222, the first recording medium P is transported by the reversing roller 9 and intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, and then stops. After that, the process returns to step S22 in Figure 15, and the second recording medium P is processed from step S22 onward.

[0117] If it is determined in step S19 that the predetermined conditions are met, the value of F in RAM203 is checked in step S20. If F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S21 it is determined whether the value of P stored in RAM203 is 0. In this case, since 0 is stored in step S42, the process moves to the "Print Operation 1" subroutine in step S70.

[0118] The "Print Operation 1" subroutine will be explained with reference to Figure 16. In step S71, it is determined whether the final row image formation operation on the first recording medium P has started. If the image formation operation has started, in step S72, the downstream leading edge of the second recording medium P in the transport direction is brought against the transport nip while maintaining the overlapping state to correct the skew of the second recording medium P. Then, in step S73, if it is determined that the final row image formation operation on the first recording medium P has finished, in step S74, the head of the second recording medium P is brought forward based on the recorded data while maintaining the overlapping state with the first recording medium P. That is, by controlling the amount of rotation of the transport roller 5, the second recording medium P is transported to the recording start position based on the position of the transport roller 5 based on the recorded data. In step S75, the feed motor 206 is switched to low-speed drive, and in step S76, the "Print Operation 1" subroutine is terminated, and the process returns to step S22 in the print operation sequence in Figure 15.

[0119] In step S22, the recording operation on the first surface of the second recording medium P is started by ejecting ink from the recording head 7 to the first surface of the second recording medium P based on the recording data of the third page. Specifically, the recording operation on the first surface of the second recording medium P is performed by repeatedly performing a transport operation in which the transport roller 5 intermittently transports the second recording medium P and an image forming operation (ink ejection operation) in which the carriage 1 moves and ink is ejected from the recording head 7. Then, in step S23, F=0 is stored in RAM 203 to remember that the recording operation has been performed on the first surface of the recording medium P, and in step S25, the "print operation" subroutine is terminated.

[0120] As previously explained, the length of the recording medium P in the transport direction is denoted as L, as shown in Figure 25. When printing on the first side of the recording medium P, the print density of the S region at the leading edge of the transport direction ((1 / 4)L portion) indicated by arrow A in Figure 25 is compared with a preset print density. If the print density of the S region falls within the preset print density, S(2)=0 is stored in RAM203; otherwise, S(2)=1 is stored. The number in parentheses indicates the number of prints.

[0121] Furthermore, as the recording operation on the second recording medium P progresses, the print density of the K region at the rear end ((1 / 4)L portion) in the transport direction, indicated by arrow A, is compared with a preset print density. If the print density of the K region falls within the preset print density range, K(2)=0 is stored in RAM203; otherwise, K(2)=1 is stored.

[0122] Furthermore, as shown in Figure 26, if the number of recording media P N is 4 or more, the value of N in S(N) and K(N) is converted to the value of M in the table, and the storage areas of S(M) and K(M) are overwritten accordingly.

[0123] Returning to the overall sequence in Figure 12, in step S210, it is determined whether F stored in RAM 203 is 0. At this stage, F=0, so in step S211, it is determined whether N stored in RAM 203 is 2. At this stage, N=2, so the process proceeds to step S101.

[0124] In step S101, it is determined whether the recording operation on the recording medium P is for the first side. Currently, the value of F in RAM 203 is 0, so it is determined that the recording operation on the recording medium P is for the first side, and the process proceeds to step S102. In step S102, if it is determined that the upstream end of the first recording medium P in the transport direction has passed the spur 12, the reversing roller 9 is driven continuously in the forward direction at 18 inches / sec in step S103. The forward drive continues until the upstream end of the first recording medium P in the transport direction reaches a position 5 mm upstream of the nip portion of the reversing roller 9 in the transport direction.

[0125] In step S104, the reversing roller 9 and the intermediate roller 15 are driven continuously at 18 inches / sec in reverse. As a result, the first recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and the intermediate roller 15. Then, in step S105, the first recording medium P is transported by the reversing roller 9 and the intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, at which point the process proceeds to step S5.

[0126] In step S5, if it is determined that the number of recording media P fed from the paper stacking unit 11 within one job is not 1 (currently N=2), then in step S6, it is determined whether F in RAM 203 is 1. Since F=0 at this stage, in step S60, the process moves to the subroutine "Feed 1 from the second transport path".

[0127] The subroutine "Feeding from the second transport path 1" will be explained with reference to Figure 14. In step S61, it is determined whether it is time for the first recording medium P to be fed from the second transport path 101 by the intermediate roller 15. When the recording medium P being recorded by the recording head 7 is fed from the paper stacking unit 11, and the subsequent recording medium P is fed from the second transport path 101, the timing for starting feeding by the intermediate roller 15 is as follows. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, the feeding start timing is when the distance between the upstream end of the second recording medium P in the transport direction and the downstream end of the first recording medium P waiting in the second transport path 101 reaches a positional relationship of 10 mm. Based on this relationship, the intermediate roller 15 is started to drive so that feeding of the first recording medium P from the second transport path 101 by the intermediate roller 15 begins.

[0128] In step S62, the feeding operation of the first recording medium P is started from the second transport path 101. Specifically, the first feed motor 206 is driven in reverse at low speed in the second drive switching state. As a result, the intermediate roller 15 and the feed roller 3 are rotated at 7.6 inches / sec. The first recording medium P is then fed toward the recording head 7 by the intermediate roller 15 and the feed roller 3.

[0129] In step S63, the RAM 203 stores P=1 to remember that the recording medium P was fed from the second transport path 101. In step S64, when the recording medium detection sensor 16 detects the downstream leading edge in the transport direction of the first recording medium P, in step S65, it is determined whether K(2)=0 and K(1)=0 in the RAM 203. Here, the first recording medium P, which is the subsequent recording medium, is inverted by the inversion roller 9 and transported on the second transport path 101. Therefore, the downstream leading edge of the first recording medium, which is the subsequent recording medium, overlapping the rear end of the second recording medium P, which is the preceding recording medium, is the upstream rear end of the first transport path 100 (region K in Figure 25). Therefore, in step S65, it is determined whether K(2)=0 and K(1)=0 in the RAM 203.

[0130] If either of the two is determined to be 1, the first feed motor 206 will not be switched to high-speed drive because curling of the recording medium P may prevent the preceding and succeeding recording media from being stacked.

[0131] Therefore, the intermediate roller 15 and the feed roller 3 are driven synchronously with the transport roller 5 at 7.6 inches / sec and the process moves to step S67. In step S67, the amount of rotation of the feed roller 3 is controlled after the downstream end of the first recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, when the downstream end of the first recording medium P in the transport direction is 10 mm before the transport nip, the transport of the first recording medium P is stopped. Then, in the next step S68, the "Feeding from the second transport path 1" subroutine is terminated.

[0132] In step S65, if it is determined that K(2)=0 and K(1)=0 in RAM203, the first feed motor 206 is switched to high-speed drive in step S66. That is, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the intermediate roller 15 and the feed roller 3 is controlled after the downstream end of the first recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, in step S67, the first recording medium P stops with its downstream end in the transport direction 10 mm in front of the transport nip. Then, in step S68, the "Feed 1 from the second transport path" subroutine is terminated, and the overall sequence in Figure 12 is returned, and in step S8, the program moves to the "Printing operation" subroutine.

[0133] The "print operation" subroutine will be explained with reference to Figure 15. If, in step S15, it is determined that the number of recording media P fed from the paper stacking unit 11 in one job is not one (at this stage, N=2), then in step S19, it is determined whether the predetermined conditions described later are met. If it is determined in step S19 that the predetermined conditions are not met, then in step S210, the process moves to the "release stacked state" subroutine.

[0134] The "Release Stacked State" subroutine will be explained with reference to Figure 18. In step S211, the value of F in RAM 203 is checked, and if F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S212 it is determined whether the value of P stored in RAM 203 is 0. In this case, since 1 is stored in step S63, the process proceeds to step S224. In step S224 it is determined that the image formation operation of the last row of the second recording medium P has been completed, and in step S225 the transport roller 5 and the discharge roller 10 transport the second recording medium P at 18 inches / sec.

[0135] In step S226, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end of the second recording medium P in the transport direction has passed the spur 12, the drive of the transport motor 205 is stopped in step S227. Since the feed motor 206 is not driven until the drive of the transport motor 205 is stopped, the first recording medium P remains stopped with its downstream end in the transport direction 10 mm before the transport nip. This eliminates the overlapping state of the second recording medium P and the first recording medium P. Furthermore, in step S228, the reversing roller 9 is continuously driven in the forward direction at 18 inches / sec, so that the second recording medium P continues to be transported until its upstream end in the transport direction reaches a position 5 mm upstream of the nip of the reversing roller 9 in the transport direction.

[0136] In step S229, the feed roller 3 is driven at 15 inches / sec to bring the leading edge of the first recording medium P into contact with the transport nip, correcting the skew of the first recording medium P, and in step S230, the first recording medium P is positioned based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the first recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. Then, in step S231, the feed motor 206 is switched to low-speed drive, and the feed roller 3 is rotated at 7.6 inches / sec.

[0137] In step S232, the reversing roller 9 and intermediate roller 15 are driven continuously at 18 inches / sec in reverse. As a result, the second recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and intermediate roller 15. Then, in step S233, the second recording medium P is transported by the reversing roller 9 and intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, and then stops. After that, the process returns to step S170 in Figure 15, and the processing from step S170 onward is performed on the first recording medium P.

[0138] If it is determined in step S19 that the predetermined conditions are met, the value of F in RAM203 is checked in step S20. If F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S21 it is determined whether the value of P stored in RAM203 is 0. At this stage, 1 is stored, so in step S80 the program proceeds to the "Print Operation 2" subroutine.

[0139] The "Print Operation 2" subroutine will be explained with reference to Figure 16. In step S81, it is determined whether the final row image formation operation on the second recording medium P has started. If the image formation operation has started, in step S82, the downstream end of the first recording medium P in the transport direction is brought against the transport nip while maintaining the overlapping state to correct the skew of the first recording medium P. Then, in step S83, if it is determined that the final row image formation operation on the second recording medium P has finished, in step S84, the first recording medium P is brought forward based on the recorded data while maintaining the overlapping state with the second recording medium P. That is, by controlling the amount of rotation of the transport roller 5, the first recording medium P is transported to the recording start position based on the position of the transport roller 5 based on the recorded data. In step S85, the feed motor 206 is switched to low-speed drive, and in step S86, the "Print Operation 2" subroutine is terminated, and the process returns to step S170 in the "Print Operation" subroutine in Figure 15.

[0140] In step S170, the recording operation is started by ejecting ink from the recording head 7 to the second side of the first recording medium P based on the recording data for the second page. Specifically, the recording operation on the second side of the first recording medium P is performed by repeatedly performing a transport operation in which the transport roller 5 intermittently transports the first recording medium P, and an image forming operation (ink ejection operation) in which the carriage 1 is moved and ink is ejected from the recording head 7. Then, in step S24, F=1 is stored in RAM 203 to remember that the recording operation has been performed on the second side of the recording medium P, and in step S25, the "print operation" subroutine is terminated.

[0141] Returning to the overall sequence in Figure 12, step S210 determines whether F stored in RAM 203 is 0. At this stage, F=1, so in step S181 it is determined that the upstream end of the second recording medium P in the transport direction has passed the spur 12, and in step S182 the reversing roller 9 is driven continuously in the forward direction at 18 inches / sec. The forward drive is continued until the upstream end of the second recording medium P in the transport direction reaches a position 5 mm upstream of the nip portion of the reversing roller 9 in the transport direction.

[0142] In step S183, the reversing roller 9 and the intermediate roller 15 are driven continuously at 18 inches / sec in reverse. As a result, the second recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and the intermediate roller 15. Then, in step S184, the second recording medium P is transported by the reversing roller 9 and the intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, at which point the process proceeds to step S5.

[0143] In step S5, if it is determined that the number of recording media P fed from the paper stacking unit 11 within one job is not one (currently N=2), then in step S6, it is determined whether F in RAM 203 is 1. Since F=1 at this stage, in step S7, it is determined whether there is recorded data from the 5th page onwards, and if there is recorded data, in step S50, the process moves to the "Feeding from paper stacking unit 3" subroutine.

[0144] The subroutine "Paper feeding from paper stacking unit 3" will be explained with reference to Figure 13. In step S51, it is determined whether it is time for the third recording medium P to be fed from the paper stacking unit 11 by the pickup roller 2. If the recording medium P being recorded by the recording head 7 is fed from the second transport path 101, and the subsequent recording medium P is fed from the paper stacking unit 11, the timing for starting feeding by the pickup roller 2 is as follows. It is assumed that the first recording medium P being recorded by the recording head 7 is being transported within the first transport path 100. The feeding start timing is when the distance between the upstream end of the first recording medium P in the transport direction, which is expected from the amount of rotation of the transport roller 5 since the start of the head-out operation and the length of the paper, and the downstream end of the third recording medium P waiting in the paper stacking unit 11 is 10 mm. Based on this relationship, the drive of the pickup roller 2 is started so that the feeding of the third recording medium P from the paper stacking unit 11 by the pickup roller 2 begins. If it is determined in step S51 that the feeding start timing has been reached, in step S52 the third recording medium P is fed from the paper stacking unit 11 at 7.6 inches / sec by the pickup roller 2. In step S53, P=0 is stored in the RAM 203 to remember that the recording medium P fed toward the recording head 7 has been fed from the paper stacking unit 11.

[0145] In step S54, when the recording medium detection sensor 16 detects the downstream leading edge of the third recording medium P in the transport direction, in step S55, it is determined whether S(1)=0 and S(3)=0 in RAM 203. Here, the first recording medium P, which is the preceding recording medium, is inverted by the inversion roller 9 and transported on the second transport path 101. Therefore, the rear end of the first recording medium P, which is the preceding recording medium, where the leading edge of the third recording medium, which is the succeeding recording medium, overlaps, is the downstream leading edge (region S in Figure 25) in the first transport path 100. Therefore, in step S55, it is determined whether S(1)=0 and S(3)=0 in RAM 203.

[0146] If either of the values ​​is determined to be 1, the first feed motor 206 is not switched to high-speed drive because the curling of the recording medium P may prevent the preceding and succeeding recording mediums from being stacked. For this reason, the pickup roller 2 and feed roller 3 remain at 7.6 inches / sec and are driven synchronously with the transport roller 5 as the process moves to step S57. In step S57, the amount of rotation of the feed roller 3 is controlled after the downstream leading edge of the third recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, when the downstream leading edge of the third recording medium P in the transport direction is 10 mm in front of the transport nip, the transport of the third recording medium P is stopped. In the next step S58, 1 is added to the value of N in RAM 203 to make N=3, and in step S59, the "Feed 3 from Paper Stacking Unit" subroutine is terminated.

[0147] In step S55, if it is determined that S(1)=0 and S(3)=0 in RAM203, the first feed motor 206 is switched to high-speed drive in step S56. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. Then, the amount of rotation of the feed roller 3 is controlled after the downstream end of the third recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, in step S57, the third recording medium P is transported so that its downstream end in the transport direction is 10 mm before the transport nip. The first recording medium P is transported intermittently based on the recorded data. By continuously driving the first feed motor 206 at high speed, the third recording medium P is placed in an overlapping state where the downstream end of the third recording medium P in the transport direction overlaps the upstream end of the first recording medium P in the transport direction. In step S58, 1 is added to the value of N in RAM203 to make N=3, and in step S59, the "Paper Loading Unit Feeding 3" subroutine is terminated. Then, the program returns to the overall sequence in Figure 12, and in step S8, it moves to the "Print Operation" subroutine.

[0148] The "print operation" subroutine will be explained with reference to Figure 15. If, in step S15, it is determined that the number of recording media P fed from the paper stacking unit 11 in one job is not one (at this stage, N=3), then in step S19, it is determined whether the predetermined conditions described later are met. If it is determined in step S19 that the predetermined conditions are not met, then in step S210, the process moves to the stack release subroutine.

[0149] The "Release Overlap State" subroutine will be explained with reference to Figure 18. In step S211, the value of F in RAM 203 is checked, and if F=1, that is, if it is determined that the recording on the recording medium P is on the second side, then in step S234 it is determined whether the value of P stored in RAM 203 is 0. At this stage, 0 is stored, so the process proceeds to step S235. In step S235 it is determined that the image formation operation of the last row of the first recording medium P has been completed, and in step S236 the transport roller 5 and the discharge roller 10 transport the first recording medium P at 18 inches / sec.

[0150] In step S237, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end in the transport direction of the first recording medium P has passed the spur 12, the drive of the transport motor 205 is stopped in step S238. Since the feed motor 206 is not driven until the drive of the transport motor 205 is stopped, the downstream end in the transport direction of the third recording medium P remains stopped at a position 10 mm before the transport nip. This eliminates the overlapping state of the first and third recording medium P. In addition, the first recording medium P is discharged from the device in step S240 by continuously driving the reversing roller 9 in the forward direction at 18 inches / sec in step S239.

[0151] In step S241, the feed roller 3 is driven at 15 inches / sec to bring the leading edge of the third recording medium P into contact with the transport nip, correcting the skew of the third recording medium P. In step S242, the third recording medium P is positioned based on the recorded data. That is, by controlling the rotation amount of the transport roller 5, the third recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. Then, in step S243, the feed motor 206 is switched to low-speed drive, and the feed roller 3 is rotated at 7.6 inches / sec. After that, the process returns to step S22 in Figure 15, and the processing from step S22 onward is performed on the third recording medium P.

[0152] If it is determined in step S19 that the predetermined conditions are met, the value of F in RAM203 is checked in step S20. If F=1, that is, if it is determined that the recording on the recording medium P is on the second side, then in step S172 it is determined whether the value of P stored in RAM203 is 0. At this stage, 0 is stored, so in step S90 the program proceeds to the "Print Operation 3" subroutine.

[0153] The "Print Operation 3" subroutine will be explained with reference to Figure 16. In step S91, it is determined whether the final row image formation operation on the first recording medium P has started. If the image formation operation has started, in step S92, while maintaining the overlapping state, the downstream leading edge of the third recording medium P in the transport direction is brought against the transport nip to perform a diagonal correction operation on the third recording medium P. Then, in step S93, if it is determined that the final row image formation operation on the first recording medium P has finished, in step S94, while maintaining the overlapping state with the third recording medium P, the beginning of the third recording medium P is brought forward based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the third recording medium P is transported to the recording start position based on the position of the transport roller 5 based on the recorded data. In step S95, the feed motor 206 is switched to low-speed drive, and in step S96, the "Print Operation 3" subroutine is terminated, and the process returns to step S22 in the "Print Operation" subroutine in Figure 15.

[0154] In step S22, the recording operation is started by ejecting ink from the recording head 7 onto the first surface of the third recording medium P based on the recording data for the fifth page. Specifically, the recording operation on the first surface of the third recording medium P is performed by repeatedly performing a transport operation in which the transport roller 5 intermittently transports the third recording medium P, and an image forming operation (ink ejection operation) in which the carriage 1 moves and ink is ejected from the recording head 7. Then, in step S23, F=0 is stored in RAM 203 to remember that the recording operation has been performed on the first surface of the recording medium P, and in step S25, the "print operation" subroutine is terminated.

[0155] As previously explained, the length of the recording medium P in the transport direction is denoted as L, as shown in Figure 25. When printing on the first side of the recording medium P, the print density of the S region at the leading edge of the transport direction ((1 / 4)L portion) indicated by arrow A in Figure 25 is compared with a preset print density. If the print density of the S region falls within the preset print density, S(3)=0 is stored in RAM203; otherwise, S(3)=1 is stored. The number in parentheses indicates the number of prints.

[0156] Furthermore, as the recording operation on the third recording medium P progresses, the print density of the K area at the rear end ((1 / 4)L portion) in the transport direction, indicated by arrow A, is compared with a preset print density. If the print density of the K area falls within the preset print density range, K(3)=0 is stored in RAM203; otherwise, K(3)=1 is stored.

[0157] Furthermore, as shown in Figure 26, if the number of recording media P N is 4 or more, the value of N in S(N) and K(N) is converted to the value of M in the table, and the storage areas of S(M) and K(M) are overwritten accordingly.

[0158] Returning to the overall sequence in Figure 12, in step S210, it is determined whether F stored in RAM 203 is 0. Since F=0 at this stage, in step S211, it is determined whether N stored in RAM 203 is 2. Since N is 3 at this stage, in step S201, it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper whether the upstream end in the transport direction of the first recording medium P has passed the spur 12. If it is determined that it has passed, in step S202 the reversing roller 9 is driven continuously at 18 inches / sec in the forward direction. Then, in step S203 the first recording medium P is ejected from the device and the process moves to step S5.

[0159] In step S5, if it is determined that the number of recording media P fed from the paper stacking unit 11 within one job is not 1 (currently N=3), then in step S6, it is determined whether F in RAM 203 is 1. Since F=0 at this stage, in step S60, the process moves to the subroutine "Feed from second transport path 1".

[0160] The subroutine "Feeding from the second transport path 1" will be explained with reference to Figure 14. In step S61, it is determined whether it is time for the second recording medium P to be fed from the second transport path 101 by the intermediate roller 15. When the recording medium P being recorded by the recording head 7 is fed from the paper stacking unit 11, and the subsequent recording medium P is fed from the second transport path 101, the timing for starting feeding by the intermediate roller 15 is as follows. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, the feeding start timing is when the distance between the upstream end in the transport direction of the third recording medium P and the downstream end in the transport direction of the second recording medium P waiting in the second transport path 101 reaches a positional relationship of 10 mm. Based on this relationship, the intermediate roller 15 is started to drive so that feeding of the second recording medium P from the second transport path 101 by the intermediate roller 15 begins.

[0161] In step S62, the feeding operation of the second recording medium P is started from the second transport path 101. Specifically, the first feed motor 206 is driven in reverse at low speed in the second drive switching state. As a result, the intermediate roller 15 and the feed roller 3 are rotated at 7.6 inches / sec. The second recording medium P is then fed toward the recording head 7 by the intermediate roller 15 and the feed roller 3.

[0162] In step S63, the RAM 203 stores P=1 to remember that the recording medium P was fed from the second transport path 101. In step S64, when the recording medium detection sensor 16 detects the downstream leading edge in the transport direction of the second recording medium P, in step S65, it is determined whether K(3)=0 and K(2)=0 in the RAM 203. Here, the second recording medium P, which is the subsequent recording medium, is inverted by the inversion roller 9 and transported on the second transport path 101. Therefore, the downstream leading edge of the second recording medium, which is the subsequent recording medium, overlapping the rear end of the third recording medium P, which is the preceding recording medium, is the upstream rear end of the first transport path 100 (region K in Figure 25). Therefore, in step S65, it is determined whether K(3)=0 and K(2)=0 in the RAM 203.

[0163] If either of the two is determined to be 1, the first feed motor 206 will not be switched to high-speed drive because curling of the recording medium P may prevent the preceding and succeeding recording mediums from being stacked. For this reason, the intermediate roller 15 and the feed roller 3 will continue to be driven synchronously with the transport roller 5 at 7.6 inches / sec and the process will proceed to step S67.

[0164] Then, in step S67, the amount of rotation of the feed roller 3 is controlled after the downstream end of the second recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, when the downstream end of the second recording medium P in the transport direction is 10 mm before the transport nip section, the transport of the second recording medium P is stopped. Then, in the next step S68, the "Feeding from the second transport path 1" subroutine is terminated.

[0165] In step S65, if it is determined that K(3)=0 and K(2)=0 in RAM203, the first feed motor 206 is switched to high-speed drive in step S66. That is, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the intermediate roller 15 and the feed roller 3 is controlled after the downstream end of the second recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, in step S67, the second recording medium P stops with its downstream end in the transport direction 10 mm before the transport nip. Then, in step S68, the "Feed from second transport path 1" subroutine is terminated, and the overall sequence in Figure 12 is returned, and in step S8, the program moves to the printing operation subroutine.

[0166] The "print operation" subroutine will be explained with reference to Figure 15. If, in step S15, it is determined that the number of recording media P fed from the paper stacking unit 11 in one job is not one (at this stage, N=3), then in step S19, it is determined whether the predetermined conditions described later are met. If it is determined in step S19 that the predetermined conditions are not met, then in step S210, the process moves to the stack release subroutine.

[0167] The "Release Overlap State" subroutine will be explained with reference to Figure 18. In step S211, the value of F in RAM 203 is checked, and if F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S212 it is determined whether the value of P stored in RAM 203 is 0. At this stage, 1 is stored, so the process proceeds to step S224. In step S224, if it is determined that the image formation operation of the last row of the third recording medium P has been completed, in step S225 the transport roller 5 and the discharge roller 10 transport the third recording medium P at 18 inches / sec. In step S226, if it is determined from the amount of rotation of the transport roller 5 since the start of the head-out operation and the length of the paper that the upstream end of the third recording medium P in the transport direction has passed the spur 12, the drive of the transport motor 205 is stopped in step S227. Since the feed motor 206 is not driven until the drive of the transport motor 205 is stopped, the second recording medium P remains stopped with its downstream end in the transport direction 10 mm before the transport nip. This eliminates the overlapping state between the third recording medium P and the second recording medium P. Furthermore, the third recording medium P is continuously transported in step S228 by driving the reversing roller 9 in the forward direction at 18 inches / sec until its upstream end in the transport direction reaches a position 5 mm upstream from the nip portion of the reversing roller 9.

[0168] In step S229, the feed roller 3 is driven at 15 inches / sec to bring the leading edge of the second recording medium P into contact with the transport nip, correcting the skew of the second recording medium P, and in step S230, the second recording medium P is positioned based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the second recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. Then, in step S231, the feed motor 206 is switched to low-speed drive, and the feed roller 3 is rotated at 7.6 inches / sec.

[0169] In step S232, the reversing roller 9 and intermediate roller 15 are driven continuously at 18 inches / sec in reverse. As a result, the third recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and intermediate roller 15. Then, in step S233, the third recording medium P is transported by the reversing roller 9 and intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, and then stops. After that, the process returns to step S170 in Figure 15, and the second recording medium P is processed from step S170 onward.

[0170] If it is determined in step S19 that the predetermined conditions are met, the value of F in RAM203 is checked in step S20. If F=0, that is, if it is determined that the recording on the recording medium P is on the first side, then in step S21 it is determined whether the value of P stored in RAM203 is 0. At this stage, 1 is stored, so in step S80 the program proceeds to the "Print Operation 2" subroutine.

[0171] The "Print Operation 2" subroutine will be explained with reference to Figure 16. In step S81, it is determined whether the final row image formation operation on the third recording medium P has started. If the image formation operation has started, in step S82, the downstream end of the second recording medium P in the transport direction is brought against the transport nip while maintaining the overlapping state to correct the skew of the second recording medium P. Then, in step S83, if it is determined that the final row image formation operation on the third recording medium P has finished, in step S84, the head of the second recording medium P is brought forward based on the recorded data while maintaining the overlapping state with the third recording medium P. That is, by controlling the amount of rotation of the transport roller 5, the second recording medium P is transported to the recording start position based on the position of the transport roller 5 based on the recorded data. In step S85, the feed motor 206 is switched to low-speed drive, and in step S86, the "Print Operation 2" subroutine is terminated, and the process returns to step S170 in the "Print Operation" subroutine in Figure 15.

[0172] In step S170, the recording operation is started by ejecting ink from the recording head 7 to the second side of the second recording medium P based on the recording data for the fourth page. Specifically, the recording operation on the second side of the second recording medium P is performed by repeatedly performing a transport operation in which the transport roller 5 intermittently transports the second recording medium P, and an image forming operation (ink ejection operation) in which the carriage 1 moves and ink is ejected from the recording head 7. Then, in step S24, F=1 is stored in the RAM 203 to remember that the recording operation has been performed on the second side of the recording medium P, and in step S25, the print operation subroutine is terminated.

[0173] Returning to the overall sequence in Figure 12, step S210 determines whether F stored in RAM 203 is 0. At this stage, F=1, so in step S181 it is determined that the upstream end of the third recording medium P in the transport direction has passed the spur 12, and in step S182 the reversing roller 9 is driven continuously in the forward direction at 18 inches / sec. The forward drive is continued until the upstream end of the third recording medium P in the transport direction reaches a position 5 mm upstream of the nip portion of the reversing roller 9 in the transport direction.

[0174] In step S183, the reversing roller 9 and intermediate roller 15 are driven continuously at 18 inches / sec in reverse. As a result, the third recording medium P is transported along the guide within the second transport path 101 by the reversing roller 9 and intermediate roller 15. Then, in step S184, the third recording medium P is transported by the reversing roller 9 and intermediate roller 15 until its downstream leading edge in the transport direction reaches a position 5 mm before the first transport path 100, at which point the process proceeds to step S5.

[0175] In step S5, if it is determined that the number of recording media P fed from the paper stacking unit 11 within one job is not one (at this stage, N=3), then in step S6, it is determined whether F in RAM 203 is 1. At this stage, F=1, so in step S7, it is determined whether there is recorded data from the 7th page onwards. In this embodiment, there is no recorded data, so in step S150, the process moves to the subroutine "Feeding from the second transport path 2".

[0176] The subroutine "Feeding from the second transport path 2" will be explained with reference to Figure 14. In step S151, it is determined whether it is time for the third recording medium P to be fed from the second transport path 101 by the intermediate roller 15. If the recording medium P on which the recording head 7 is performing a recording operation is fed from the second transport path 101, and the subsequent recording medium P is also fed from the second transport path 101, the timing for starting feeding by the intermediate roller 15 is as follows. Based on the amount of rotation of the transport roller 5 from the start of the lead-out operation and the length of the paper, the feeding start timing is when the distance between the upstream end of the second recording medium P in the transport direction and the downstream end of the third recording medium P in the transport direction within the second transport path 101 reaches a positional relationship of 10 mm. Based on this relationship, the intermediate roller 15 is started to drive so that feeding of the third recording medium P from the second transport path 101 by the intermediate roller 15 begins. In step S152, the feeding operation of the third recording medium P is started from the second transport path 101. Specifically, the first feed motor 206 is driven in reverse at a low speed while in the second drive switching state. As a result, the intermediate roller 15 and the feed roller 3 rotate at 7.6 inches / sec. The intermediate roller 15 and the feed roller 3 then feed the third recording medium P toward the recording head 7. In step S153, P=1 is stored in the RAM 203 to remember that the recording medium P was fed from the second transport path 101.

[0177] In step S154, when the recording medium detection sensor 16 detects the downstream leading edge of the third recording medium P in the transport direction, step S155 determines whether there is recorded data for pages 7 and beyond. In this embodiment, there is no recorded data for pages 7 and beyond, but the case where there is will be explained below.

[0178] If it is determined in step S155 that there is recorded data for pages 7 and beyond, the process proceeds to step S160, where it is determined whether S(2)=0 and S(4)=0 for RAM203. If either of these is determined to be 1, the first feed motor 206 is not switched to high-speed drive because curling of the recording medium P may prevent the preceding and succeeding recording media from being stacked. For this reason, the intermediate roller 15 and the feed roller 3 are driven synchronously with the transport roller 5 at 7.6 inches / sec, and the process proceeds to step S158.

[0179] Then, in step S158, the amount of rotation of the feed roller 3 is controlled after the downstream end of the fourth recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, when the downstream end of the fourth recording medium P in the transport direction is 10 mm in front of the transport nip section, the transport of the fourth recording medium P is stopped. Then, in the next step S159, the "Feeding from the second transport path 2" subroutine is terminated, and the system returns to the overall sequence in Figure 12, and in step S8, the system moves to the printing operation subroutine.

[0180] In step S160, if it is determined that S(2)=0 and K(4)=0 in RAM203, the first feed motor 206 is switched to high-speed drive in step S157. That is, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the intermediate roller 15 and the feed roller 3 is controlled after the downstream end of the fourth recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, in step S158, the fourth recording medium P stops with its downstream end in the transport direction 10 mm in front of the transport nip. Then, in step S159, the "Feed 2 from the second transport path" subroutine is terminated, and the overall sequence in Figure 12 is returned, and in step S8, the program moves to the printing operation subroutine.

[0181] In this embodiment, there is no recorded data beyond page 7, so if it is determined in step S155 that there is no recorded data beyond page 7, the process proceeds to step S156, where it is determined whether K(2)=0 and K(3)=0 for RAM203. If either one is determined to be 1, it is possible that the preceding and succeeding recording media cannot be stacked due to curling of the recording media P, so the first feed motor 206 is not switched to high-speed drive. For this reason, the intermediate roller 15 and the feed roller 3 are driven synchronously with the transport roller 5 at 7.6 inches / sec and the process proceeds to step S158.

[0182] Then, in step S158, the amount of rotation of the feed roller 3 is controlled after the downstream end of the third recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, when the downstream end of the third recording medium P in the transport direction is 10 mm in front of the transport nip section, the transport of the third recording medium P is stopped. Then, in the next step S159, the "Feeding from the second transport path 2" subroutine is terminated.

[0183] In step S160, if it is determined that K(2)=0 and K(3)=0 in RAM203, the first feed motor 206 is switched to high-speed drive in step S157. That is, the intermediate roller 15 and the feed roller 3 rotate at 20 inches / sec. The amount of rotation of the intermediate roller 15 and the feed roller 3 is controlled after the downstream end of the third recording medium P in the transport direction is detected by the recording medium detection sensor 16. As a result, in step S158, the third recording medium P stops with its downstream end in the transport direction 10 mm in front of the transport nip. Then, in step S159, the "Feed 2 from the second transport path" subroutine is terminated, and the overall sequence in Figure 12 is returned, and in step S8, the program moves to the "Printing operation" subroutine.

[0184] The "print operation" subroutine will be explained with reference to Figure 15. If, in step S15, it is determined that the number of recording media P fed from the paper stacking unit 11 in one job is not one (at this stage, N=3), then in step S19, it is determined whether the predetermined conditions described later are met. If it is determined in step S19 that the predetermined conditions are not met, then in step S210, the process moves to the "release stacked state" subroutine.

[0185] The "Release Overlap State" subroutine will be explained with reference to Figure 18. In step S211, the value of F in RAM 203 is checked, and if F=1, that is, if it is determined that the recording on the recording medium P is on the second side, then in step S234 it is determined whether the value of P stored in RAM 203 is 0. At this stage, 1 is stored, so the process proceeds to step S244.

[0186] In step S244, when it is determined that the image formation operation for the last row of the second recording medium P has finished, in step S245 the transport roller 5 and the discharge roller 10 transport the second recording medium P at 18 inches / sec. In step S246, when it is determined from the amount of rotation of the transport roller 5 since the start of the heading operation and the length of the paper that the upstream end in the transport direction of the second recording medium P has passed the spur 12, the drive of the transport motor 205 is stopped in step S247. Since the feed motor 206 is not driven until the drive of the transport motor 205 is stopped, the downstream end in the transport direction of the third recording medium P remains stopped at a position 10 mm before the transport nip. As a result, the overlapping state of the second and third recording medium P is resolved.

[0187] In step S248, the feed roller 3 is driven at 15 inches / sec to bring the leading edge of the third recording medium P into contact with the transport nip, correcting the skew of the third recording medium P. In step S249, the third recording medium P is positioned based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the third recording medium P is transported to the recording start position based on the position of the transport roller 5 according to the recorded data. Then, in step S250, the feed motor 206 is switched to low-speed drive, and the feed roller 3 is rotated at 7.6 inches / sec.

[0188] Then, the process returns to step S173 in Figure 15, and the processing from step S173 onward is performed on the third recording medium P and the second recording medium P.

[0189] If it is determined in step S19 that the predetermined conditions are met, the value of F in RAM203 is checked in step S20. If F=1, that is, if it is determined that the recording on the recording medium P is on the second side, then in step S172 it is determined whether the value of P stored in RAM203 is 0. At this stage, 1 is stored, so in step S70 the program proceeds to the "Print Operation 1" subroutine.

[0190] The "Print Operation 1" subroutine will be explained with reference to Figure 16. In step S71, it is determined whether the final row image formation operation on the second recording medium P has started. If the image formation operation has started, in step S72, while maintaining the overlapping state, the downstream leading edge of the third recording medium P in the transport direction is brought against the transport nip to perform a diagonal correction operation on the third recording medium P. Then, in step S73, if it is determined that the final row image formation operation on the second recording medium P has finished, in step S74, while maintaining the overlapping state with the second recording medium P, the beginning of the third recording medium P is brought forward based on the recorded data. That is, by controlling the amount of rotation of the transport roller 5, the third recording medium P is transported to the recording start position based on the position of the transport roller 5 based on the recorded data. In step S75, the feed motor 206 is switched to low-speed drive, and in step S76, the "Print Operation 1" subroutine is terminated, and the process returns to step S173 in the "Print Operation" subroutine in Figure 15.

[0191] In step S173, the recording operation is started by ejecting ink from the recording head 7 to the second side of the third recording medium P based on the recording data for the sixth page. Specifically, the recording operation on the second side of the third recording medium P is performed by repeatedly performing a transport operation in which the transport roller 5 intermittently transports the third recording medium P, and an image forming operation (ink ejection operation) in which the carriage 1 is moved and ink is ejected from the recording head 7. Then, in step S174, F=1 is stored in the RAM 203 to remember that the recording operation has been performed on the second side of the recording medium P, and the process moves to the "Ejection Operation 1" subroutine in step S130.

[0192] The "Ejection Operation 1" subroutine will be explained with reference to Figure 17. In step S121, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end in the transport direction of the second recording medium P has passed the spur 12, then in step S122 the reversing roller 9 is driven continuously at 18 inches / sec in the forward direction. Then, in step S123 the second recording medium P is ejected from the device, and in step S124 the "Ejection Operation 1" subroutine ends. Then, the process returns to step S175 in the "Print Operation" subroutine in Figure 15, where it is determined whether there is recorded data from page 7 onwards. If it is determined that there is no recorded data, the process moves to the "Ejection Operation 2" subroutine in step S130.

[0193] The "Ejection Operation 2" subroutine will be explained with reference to Figure 17. In step S131, if it is determined from the amount of rotation of the transport roller 5 since the start of the lead-out operation and the length of the paper that the upstream end in the transport direction of the third recording medium P has passed the spur 12, then in step S132 the reversing roller 9 is driven continuously at 18 inches / sec in the forward direction. Then, in step S133 the third recording medium P is ejected from the device, and in step S134 the "Ejection Operation 2" subroutine is terminated. Then, the process returns to step S176 in the "Printing Operation" subroutine in Figure 15, and in step S176 the duplex printing operation is terminated.

[0194] Figures 21 and 22 illustrate the operation of stacking a successor recording medium on top of a prior recording medium in this embodiment. The operation of forming a stacked state in which the leading edge of the successor recording medium is placed on top of the trailing edge of the prior recording medium, as described in Figures 2 to 11, will be explained.

[0195] Figures 21 and 22 are enlarged views of the area between the feeding nip section formed by the feeding roller 3 and the feeding driven roller 4, and the conveying nip section formed by the conveying roller 5 and the pinch roller 6. In this embodiment, a configuration is described that includes a recording medium holding lever to suppress the lifting of the rear end of the recording medium P.

[0196] The process by which the recording medium is transported by the transport roller 5 and the feed roller 3 will be described in order as three states. The first state, in which the subsequent recording medium follows the preceding recording medium, will be described with reference to ST30 and ST31 in Figure 21. The second state, in which the subsequent recording medium is placed on top of the preceding recording medium, will be described with reference to ST32 and ST33 in Figure 22. The third state, in which it is determined whether to maintain the stacked state and perform a diagonal correction operation for the subsequent recording medium, will be described with reference to ST34 in Figure 22.

[0197] In ST30 shown in Figure 21, the feed roller 3 is controlled to transport the subsequent recording medium P, and the recording medium detection sensor 16 detects the leading edge of the subsequent recording medium P. The first section A1 is defined as the range from the recording medium detection sensor 16 to position P1, where the subsequent recording medium P can be placed on top of the preceding recording medium P. In the first section A1, the leading edge of the subsequent recording medium P follows the trailing edge of the preceding recording medium P. P1 is determined by the configuration of the mechanism.

[0198] In the first state, there are cases in the first section A1 where the tracking operation is stopped. As shown in ST31 in Figure 21, if the leading edge of the trailing recording medium P overtakes the trailing edge of the preceding recording medium P before reaching P1, the operation of overlapping the trailing recording medium with the preceding recording medium is not performed.

[0199] In ST32 of Figure 22, the section from P1 to the position P2 where the recording medium retaining lever 17 is provided is defined as the second section A2. In the second section A2, the operation of placing the subsequent recording medium P on top of the preceding recording medium P is performed.

[0200] In the second state, there are cases in the second section A2 where the operation of stacking the subsequent recording medium on top of the preceding recording medium is stopped. As shown in ST33 in Figure 22, if the leading edge of the subsequent recording medium P cannot catch up to the trailing edge of the preceding recording medium P within the second section A2, the operation of stacking the subsequent recording medium on top of the preceding recording medium cannot be performed.

[0201] In ST34 of Figure 22, the section from P2 to P3 is defined as the third section A3. P3 is, for example, the position of the leading edge when the subsequent recording medium P stops in step S45 of Figure 13. The subsequent recording medium P is transported with the leading edge of the subsequent recording medium P stacked on top of the preceding recording medium P until it reaches P3. In the third section A3, a decision is made as to whether or not to bring the subsequent recording medium P into contact with the transport nip while maintaining the stacked state and bringing it forward. That is, a decision is made as to whether to maintain the stacked state and bring it forward after the diagonal correction operation, or to release the stacked state and bring it forward after the diagonal correction operation.

[0202] Figure 23 is a flowchart illustrating the diagonal correction operation of the subsequent recording medium in this embodiment. The determination of whether the predetermined conditions described in S19 of Figure 15 are met will be explained in detail below.

[0203] This section describes the determination process for whether to perform a diagonal correction operation by bringing the leading edge of the subsequent recording medium P into contact with the transport nip while maintaining the overlapping state of the preceding recording medium P and the succeeding recording medium P, or to release the overlapping state of the preceding recording medium P and the succeeding recording medium P before bringing the leading edge of the succeeding recording medium P into contact with the transport nip and performing the diagonal correction operation.

[0204] The process begins in step S301. In step S302, it is determined whether the leading edge of the subsequent recording medium P has reached the determination position (Figure 22: P3 of ST34). If it has not reached this point (step S302: NO), it is unclear whether the leading edge of the subsequent recording medium P will hit the transport nip section after a predetermined amount of transport, so it is decided to perform a diagonal correction operation on only the subsequent recording medium (step S303), and the determination operation ends (step S304). That is, after the rear end of the preceding recording medium P has passed the transport nip section, the diagonal correction operation is performed by making only the subsequent recording medium P hit the transport nip section, and then the leading edge is brought out with only the subsequent recording medium P in place.

[0205] On the other hand, if the leading edge of the subsequent recording medium P has reached the determination position P3 (step S302: YES), it is determined whether the trailing edge of the preceding recording medium P has passed the transport nip section (step S305). If it is determined that it has passed (step S305: YES), the preceding and succeeding recording mediums do not overlap, so it is decided to perform a diagonal correction operation on the succeeding recording medium only (step S306). That is, the diagonal correction operation is performed by bringing only the succeeding recording medium P into contact with the transport nip section, and then the recording medium P is brought forward in its current state.

[0206] On the other hand, if it is determined that the rear end of the preceding recording medium P has not passed through the transport nip section (step S305: NO), it is determined whether the amount of overlap between the rear end of the preceding recording medium P and the front end of the succeeding recording medium P is less than a threshold (step S307). The position of the rear end of the preceding recording medium P is updated in accordance with the recording operation on the preceding recording medium P. The position of the front end of the succeeding recording medium P is at the aforementioned determination position. That is, the amount of overlap decreases in accordance with the recording operation of the preceding recording medium P. If it is determined that the amount of overlap is less than a threshold (step S307: YES), the overlapping state is released and the system decides to perform a skew correction operation on the succeeding recording medium only (step S308). That is, after the image forming operation on the preceding recording medium P is completed, the succeeding recording medium P is not transported together with the preceding recording medium P. Specifically, the transport roller 5 is driven by the transport motor 205 to transport the preceding recording medium P. However, the feed roller 3 is not driven. Therefore, the overlapping state is released. Furthermore, the subsequent recording medium P is brought into contact with the transport nip section to correct its skew, and then the recording medium P is brought to the front of the slide.

[0207] If the amount of overlap is determined to be greater than or equal to a threshold (step S307: NO), a determination is made as to whether the subsequent recording medium P will reach the spur 12 when the subsequent recording medium P is brought forward (step S309). If it is determined that the subsequent recording medium P will not reach the spur 12 (step S309: NO), the overlapping state is released and a diagonal correction operation is decided to be performed on the subsequent recording medium only (step S310). In other words, after the image forming operation of the preceding recording medium P is completed, the subsequent recording medium P is not transported together with the preceding recording medium P. Specifically, the transport roller 5 is driven by the transport motor 205 to transport the preceding recording medium P. However, the feed roller 3 is not driven. Therefore, the overlapping state is released. Furthermore, the diagonal correction operation is performed by bringing only the subsequent recording medium P against the transport nip, and then the beginning is brought forward with only the subsequent recording medium P.

[0208] If it is determined that the subsequent recording medium P has reached the spur 12 (step S309: YES), it is determined whether there is a gap between the last row of the preceding recording medium and the row before that last row (step S311). If it is determined that there is no gap (step S311: NO), the overlapping state is released and it is decided to perform a skew correction operation on the subsequent recording medium only (step S312). If it is determined that there is a gap (step S311: YES), the skew correction operation of the subsequent recording medium P is performed while maintaining the overlapping state, and then the head is brought forward. That is, after the image forming operation of the preceding recording medium P is completed, the subsequent recording medium P is brought against the transport nip section while still overlapping with the preceding recording medium P. Specifically, the transport roller 5 and the transport roller 3 are rotated by driving the transport motor 205 and the feed motor 206 simultaneously. After the skew correction operation, the head of the subsequent recording medium P is brought forward while still overlapping with the preceding recording medium P.

[0209] In this way, a determination operation is performed to determine whether to maintain or release the overlapping state of the preceding recording medium P and the succeeding recording medium P.

[0210] Figure 24 is a flowchart illustrating the configuration for calculating the leading edge position of the subsequent recording medium after it has been led out, in this embodiment.

[0211] Step S401 initiates the process. In step S402, the recordable area of ​​the recording medium size is read. The leading edge recordable position, i.e., the upper margin, is identified, and the upper margin of the recordable area is set as the leading edge position (step S403). Here, the leading edge position is defined by the distance from the transport nip section.

[0212] Next, the first recorded data is read (step S404). This identifies the position of the first recorded data from the leading edge of the recording medium (detection of the non-recording area), and a determination is made as to whether the distance from the leading edge of the recording medium to the first recorded data is greater than the previously set leading edge position (step S405). If the distance from the leading edge of the recording medium to the first recorded data is greater than the previously set leading edge position (step S405: YES), the leading edge position is updated to the distance from the leading edge of the recording medium to the first recorded data (step S406). If the distance from the leading edge of the recording medium to the first recorded data is less than or equal to the previously set leading edge position (step S405: NO), the process proceeds to step S407.

[0213] Next, the first carriage movement command is created (step S407). Next, it is determined whether the amount of recording medium to be transported for the first carriage movement is greater than the previously set leading position (step S408). If the amount of recording medium to be transported for the first carriage movement is greater than the previously set leading position (step S408: YES), the leading position is updated to the amount of recording medium to be transported for the first carriage movement (step S409). If the amount of recording medium to be transported for the first carriage movement is less than or equal to the previously set leading position (step S408: NO), the leading position is not updated. As described above, the leading position of the subsequent recording medium P is determined (step S410), and the process ends (step S411). Based on the determined leading position, it is possible to determine whether the subsequent recording medium P will reach the spur 12 when the leading edge of the subsequent recording medium P is brought forward (Figure 23: step S309).

[0214] As described above, according to the above embodiment, the control to overlap the leading edge of the successor recording medium with the trailing edge of the preceding recording medium can be performed regardless of whether the recording medium is supplied from the paper stacking unit or the second transport path.

[0215] In the embodiment described above, the case where the recording medium P is discharged outside the device by being transported downstream in the transport direction by a reversing roller 9 that reverses the transport direction of the recording medium was explained. However, the same effect can be obtained by providing a discharge path between the reversing roller 9 and the discharge roller 10 for transporting the recording medium P outside the device, and by providing a transport direction switching member that switches the direction in which the recording medium P moves toward the reversing roller 9 and toward the discharge path.

[0216] (Other embodiments) Furthermore, the present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0217] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0218] 1: Carriage, 2: Pickup roller, 3: Feeding roller, 4: Feeding driven roller, 5: Conveyor roller, 6: Pinch roller, 7: Recording head, 8: Platen, 9: Reversing roller, 10: Discharge roller, 11: Paper stacking section, 12: Spur, 13: Reversing driven roller, 14: Intermediate driven roller, 15: Intermediate roller, 16: Recording medium detection sensor, 17: Recording medium press lever, 100: First transport path, 101: Second transport path, P: Recording medium

Claims

1. A supply means for supplying recording media, A feeding roller for transporting the recording medium supplied by the aforementioned supply means, A conveying roller that conveys the recording medium conveyed by the aforementioned feeding roller in the conveying direction, Downstream of the transport roller, there is a recording means for ejecting ink onto a recording medium transported by the transport roller to record an image, A carriage that moves the recording means in a direction intersecting the transport direction, A recording device comprising: a reversal path for returning a recording medium, which has been recorded by the recording means and reversed front and back, to the feeding roller, A first control is performed to overlap the first recording medium, on which the first surface is being recorded by the recording means, with the second recording medium supplied from the supply means between the supply roller and the transport roller. A second control is provided to stack the first recording medium, which has been transported from the reversing path and whose first surface has been recorded by the recording means, between the feed roller and the transport roller, with respect to the second recording medium whose first surface has been recorded by the recording means. A recording device characterized by having control means capable of performing the following.

2. The recording apparatus according to Claim 1, characterized in that the control means performs a third control, which involves stacking the third recording medium supplied from the supply means between the supply roller and the transport roller with respect to the first recording medium on which the second surface of the back of the first surface is being recorded.

3. Downstream of the recording means in the transport direction, there is an discharge path for discharging the recording medium on which the image is recorded. The recording apparatus according to claim 1 or 2, characterized in that a reversing roller is disposed in the discharge path, which rotates in a first direction to discharge the recording medium and rotates in a second direction opposite to the first direction to transport the recording medium recorded by the recording means to the reversing path.

4. A guide portion is disposed between the feeding roller and the conveying roller, The reversing path includes an intermediate roller, The recording apparatus according to any one of claims 1 to 3, characterized in that the intermediate roller transports the recording medium from the reversing path to the guide section.

5. The recording device according to claim 1, further characterized by comprising a detection sensor provided between the feeding roller and the conveying roller for detecting the edge of the recording medium.

6. The recording apparatus according to claim 1, wherein, in the second control, the control means performs a diagonal correction operation to bring the first recording medium conveyed from the reversing path into contact with the conveying roller when the conveying roller is stopped.

7. The recording device according to any one of claims 1 to 5, characterized in that, in the second control, the control means determines whether or not to perform control to superimpose the first recording medium, on which the first surface is recorded, onto the rear end of the second recording medium, based on the recorded data.

8. The recording device according to claim 7, characterized in that the recorded data is the print density in a preset recording area.

9. The recording apparatus according to claim 8, wherein, in the second control, the control means determines whether or not to perform control to superimpose the first recording medium, on which the first surface is recorded, onto the rear end of the second recording medium, based on the recorded data of the preset areas in which the first recording medium and the second recording medium overlap each other.

10. The recording apparatus according to claim 8 or 9, characterized in that the control means determines whether or not to perform control to superimpose the second recording medium on the rear end of the first recording medium by comparing the print density of the preset area with a preset print density.

11. The recording apparatus according to any one of claims 8 to 10, characterized in that the preset recording area is a first area at the leading edge of the recording medium and a second area at the rear end of the recording medium.

12. The recording apparatus according to claim 4, wherein, in the second control, the control means makes the first recording medium catch up to the second recording medium by setting the transport speed of the intermediate roller that transports the first recording medium to a speed faster than that of the transport roller while the second recording medium is being transported by the transport roller.

13. The recording apparatus according to claim 3, characterized in that the control means sets the transport speed of the reversing roller in the first direction to a speed faster than the transport roller that transports the second recording medium on which recording is being performed by the recording means, thereby releasing the overlap between the rear end of the first recording medium and the front end of the second recording medium.

14. The recording apparatus according to any one of claims 1 to 13, characterized in that the control means detects the leading edge position of the second recording medium before the recording means performs the recording operation of the last line on the first recording medium.

15. The recording apparatus according to any one of claims 1 to 14, characterized in that, if the control means determines that it is not to perform control to overlap the leading edge of the second recording medium with the rear edge of the first recording medium, it stops transporting the second recording medium and transports the first recording medium to a position facing the recording means.

16. A method for controlling a recording apparatus comprising: a supply means for supplying a recording medium; a feed roller for transporting the recording medium supplied by the supply means; a transport roller for transporting the recording medium transported by the feed roller in the transport direction; a recording means downstream of the transport roller for ejecting ink onto the recording medium transported by the transport roller to record an image; a carriage for moving the recording means in a direction intersecting the transport direction; and a reversal path for returning the recording medium, which has been recorded on by the recording means and reversed, back to the feed roller, wherein A first control is performed to overlap the first recording medium, on which the first surface is being recorded by the recording means, with the second recording medium supplied from the supply means between the supply roller and the transport roller. A second control is provided to stack the first recording medium, which has been transported from the reversing path and whose first surface has been recorded by the recording means, between the feed roller and the transport roller, with respect to the second recording medium whose first surface has been recorded by the recording means. A control method for a recording device, characterized by having a control step that enables the following:

17. The control method for a recording device according to claim 16, characterized in that the control step involves performing a third control, in which a third recording medium supplied from the supply means is placed between the supply roller and the transport roller on top of the first recording medium on which the second surface of the back of the first surface is being recorded.

18. Downstream of the recording means in the transport direction, there is an discharge path for discharging the recording medium on which the image is recorded. A control method for a recording apparatus according to claim 16 or 17, characterized in that a reversing roller is arranged in the discharge path to rotate in a first direction to discharge a recording medium and to rotate in a second direction opposite to the first direction to transport the recording medium recorded by the recording means to the reversing path.

19. It comprises a guide section positioned between the feeding roller and the conveying roller, and an intermediate roller provided in the reversing path, The control method for a recording device according to claim 16 or 17, characterized in that the intermediate roller transports the recording medium from the reversing path to the guide section.

20. The control method for a recording device according to claim 16, characterized in that it is provided between the feeding roller and the transport roller and includes a detection sensor for detecting the edge of the recording medium.

21. The control method for a recording device according to claim 16, characterized in that, in the second control step, when the transport roller is stopped, a diagonal correction operation is performed to bring the first recording medium transported from the reversing path into contact with the transport roller.

22. The control method for a recording device according to any one of claims 16 to 20, characterized in that in the control step, in the second control, it is determined whether or not to perform control to superimpose the first recording medium, on which the first surface is recorded, onto the rear end of the second recording medium, based on the recorded data.

23. The control method for a recording device according to claim 22, characterized in that the recorded data is the print density in a preset recording area.

24. The control method for a recording device according to claim 23, characterized in that in the control step, in the second control, it is determined whether or not to perform control to superimpose the first recording medium, on which the first surface is recorded, onto the rear end of the second recording medium, based on the recorded data of the preset areas in which the first recording medium and the second recording medium overlap each other.

25. The control step is characterized in that a control of a recording device according to claim 23 or 24 is made by comparing the print density of the preset area with a preset print density to determine whether or not to perform control to overlap the second recording medium with the rear end of the first recording medium.

26. A program for causing a computer to execute the control method for the recording device described in claim 16.

27. A computer-readable storage medium storing a program for causing a computer to execute the control method of the recording device described in claim 16.

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