JP6667585B2 - Recording device and control method therefor, program, storage medium - Google Patents

Description

  The present invention relates to a sheet conveying technique in a recording apparatus having a recording head.

  2. Description of the Related Art In recent years, in printing apparatuses, higher printing speed is expected to improve productivity. One of the methods for achieving higher printing speed is to reduce the interval between continuously supplied recording sheets. No. As a technique for reducing the interval between recording sheets, in addition to simply reducing the interval between the preceding sheet and the succeeding sheet, the recording sheet is conveyed by overlapping the margin area at the trailing edge of the preceding sheet and the leading edge of the succeeding sheet. There is a method of forming an image in a state in which the images are overlapped (see Patent Document 1). This means that image formation is performed in a state in which useless portions (recording sheet intervals, recording sheet margins) other than the image forming area are eliminated to the utmost extent, and in terms of speeding up printing, it is extremely difficult. It is an effective means.

JP 2001-324844 A

  However, particularly in an ink jet recording apparatus, when high-density printing using a large amount of ink is performed in an area where recording sheets overlap, a wavy wrinkle called cockling occurs on the recording sheet due to the moisture of the ink. For example, when a part of the leading edge of the succeeding sheet is overlapped with the marginal area at the trailing edge of the preceding sheet, the back side of the sheet is restrained by a flat plate. For this reason, the recording sheet is lifted by the occurrence of cockling, and the recording sheet is rubbed against the recording head, so that the recording sheet cannot be contaminated, cannot be conveyed to a discharge roller or the like, and a paper jam may occur. In addition, since the distance between the recording head and the surface of the recording sheet becomes unstable, there is a possibility that the image quality may be degraded due to displacement of the ink landing position.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of suppressing inconvenience that occurs when performing high-density printing by transporting a succeeding sheet over a preceding sheet and performing high-density printing. It is.

In order to solve the above problems and achieve the object, a recording apparatus according to the present invention includes a feeding unit that feeds a sheet, a feeding unit that feeds a sheet fed by the feeding unit, and the feeding unit. Means for performing recording by discharging ink on a sheet conveyed by the printer, and inversion for inverting the front and back of the sheet on which recording has been performed on the first surface by the recording means and conveying the sheet to the conveying means A path, a conveyance control means for controlling conveyance of a preceding sheet and a succeeding sheet fed next to the preceding sheet, and superimposing a leading end of the succeeding sheet on the preceding sheet whose front and back are reversed by the reversing path , Wherein the conveyance control means is configured to determine an overlapping amount of the preceding sheet and the succeeding sheet based on an amount of ink ejected to a predetermined area of at least one of the first surface and the second surface of the preceding sheet. To A constant.

  Advantageous Effects of Invention According to the present invention, it is possible to suppress sheet contamination, paper jam, deterioration in image quality, and the like, which occur when high-density printing is performed by superimposing a succeeding sheet on a preceding sheet and performing printing at high speed. .

FIG. 3 is a diagram for explaining an operation of continuous continuous feeding in the recording apparatus according to the embodiment. FIG. 3 is a diagram for explaining an operation of continuous continuous feeding in the recording apparatus according to the embodiment. FIG. 3 is a diagram for explaining an operation of continuous continuous feeding in the recording apparatus according to the embodiment. FIG. 2 is a diagram illustrating a configuration of a pickup roller according to the embodiment. FIG. 2 is a functional block diagram of the recording apparatus according to the embodiment. 9 is a flowchart illustrating the operation of the continuous feeding according to the embodiment. FIG. 4 is a diagram illustrating an operation of superimposing a succeeding sheet on a preceding sheet according to the embodiment. FIG. 4 is a diagram illustrating an operation of superimposing a succeeding sheet on a preceding sheet according to the embodiment. 5 is a flowchart illustrating a process for determining an overlapping amount Lt (B) according to the first embodiment. 9 is a flowchart illustrating processing for determining a succeeding sheet-induced overlap reduction amount Y (B) according to the first embodiment. 5 is a flowchart illustrating processing for detecting a recording density according to the first embodiment. FIG. 2 is a schematic diagram illustrating an overlap region of recording sheets according to the first embodiment. FIG. 4 is a schematic diagram showing a state of cockling of a succeeding sheet superimposed on a preceding sheet in the first embodiment. FIG. 3 is an explanatory diagram of recording density detection area division according to the first embodiment. FIG. 6 is a diagram illustrating a threshold table for calculating a subsequent sheet-induced overlap reduction amount Y (B) according to the first embodiment. 9 is a flowchart illustrating a process for determining a preceding sheet-induced overlap amount Lb (A) according to the second embodiment. FIG. 9 is a schematic diagram showing cockling in the vicinity of the rear end of a preceding sheet in a second embodiment. FIG. 13 is a schematic diagram illustrating a state of floating of a succeeding sheet superimposed on a preceding sheet cockled in the second embodiment. 9 is a flowchart illustrating a process for determining a preceding sheet-induced overlap reduction amount X (A) according to the second embodiment. FIG. 9 is a schematic diagram illustrating a superposition region of recording sheets according to the second embodiment. FIG. 9 is a schematic diagram illustrating a recording density detection area and a unit area according to the second embodiment. FIG. 11 is a diagram illustrating a function for calculating a preceding sheet-induced overlap reduction amount X (A) according to the second embodiment. FIG. 13 is a diagram illustrating a table for determining a function for calculating a preceding sheet-induced overlap reduction amount X (A) in the second embodiment. 13 is a flowchart illustrating a process for determining an overlap amount Lt (B) according to the third embodiment. FIG. 9 is a schematic diagram illustrating a superposition region of recording sheets according to a third embodiment. FIG. 14 is a diagram showing a table changed for each recording condition in order to determine a function for obtaining the preceding sheet-induced overlap reduction amount X (A) in the third embodiment. FIG. 14 is a diagram showing a table changed for each recording condition in order to determine a threshold value for calculating a succeeding sheet-induced overlap reduction amount Y (B) in the third embodiment. 15 is a flowchart illustrating a process for determining a succeeding sheet-induced overlap reduction amount Y (B) according to the fourth embodiment. FIG. 13 is a diagram for explaining the operation of continuous feeding in double-sided printing according to the fifth embodiment. FIG. 13 is a diagram for explaining the operation of continuous feeding in double-sided printing according to the fifth embodiment. 15 is a flowchart illustrating the continuous continuous feeding operation in double-sided printing according to the fifth embodiment. 15 is a flowchart illustrating the continuous continuous feeding operation in double-sided printing according to the fifth embodiment. 17 is a flowchart showing a process for determining a preceding sheet-induced overlap amount Lb (A) according to the fifth embodiment. FIG. 14 is a schematic diagram illustrating a superposition region of recording sheets according to a fifth embodiment. FIG. 14 is a schematic diagram illustrating a superposition region of recording sheets according to a fifth embodiment. 20 is a flowchart illustrating a process for determining a preceding sheet-induced overlap amount Lb (A) according to the sixth embodiment. FIG. 17 is a schematic diagram illustrating a superposition region of recording sheets according to a sixth embodiment. 17 is a flowchart illustrating a process for determining a preceding sheet-induced overlap reduction amount X (A) according to the sixth embodiment. FIG. 18 is an explanatory diagram of recording density detection area division according to the sixth embodiment. 17 is a flowchart illustrating a process for determining an overlapping amount Lt (B) according to the seventh embodiment. FIG. 19 is a schematic diagram illustrating an overlap region of recording sheets according to a seventh embodiment. 20 is a flowchart showing a process for determining an overlap amount Lt (B) according to the eighth embodiment. 20 is a flowchart showing a process for determining an overlap amount Lt (B) according to the eighth embodiment. 20 is a flowchart illustrating processing for determining a succeeding sheet-induced overlap reduction amount Y (B) according to the eighth embodiment. 20 is a flowchart illustrating processing for determining a succeeding sheet-induced overlap reduction amount Y (B) according to the eighth embodiment. FIG. 19 is a schematic diagram showing an overlap region of recording sheets according to the eighth embodiment. FIG. 18 is an explanatory diagram of recording density detection area division according to the eighth embodiment. FIG. 21 is a side sectional view schematically showing the device configuration of the ninth embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIGS. 1 to 3 are side sectional views schematically showing a main configuration of a recording apparatus according to an embodiment of the present invention and an operation of continuous feeding. First, a schematic configuration of a printing apparatus according to the present embodiment will be described with reference to FIG.

  In ST1 of FIG. 1, 1 is a recording sheet. The plurality of recording sheets 1 are stacked on a feed tray 11 (stacking unit). Reference numeral 2 denotes a pickup roller which abuts on the uppermost recording sheet 1 stacked on the feed tray 11 and picks up this recording sheet. Reference numeral 3 denotes a feeding roller for feeding the recording sheet 1 picked up by the pickup roller 2 to the downstream side in the sheet conveying direction. Reference numeral 4 denotes a feed driven roller which is urged by the feed roller 3 to pinch and feed the recording sheet 1 together with the feed roller 3.

  Reference numeral 5 denotes a conveying roller for conveying the recording sheet 1 fed by the feeding roller 3 and the feeding driven roller 4 to a position facing the recording head 7. Reference numeral 6 denotes a pinch roller which is urged by the transport roller 5 to pinch and transport the recording sheet together with the transport roller 5.

  Reference numeral 7 denotes a recording head that performs recording on the recording sheet 1 transported by the transport roller 5 and the pinch roller 6. In the present embodiment, an ink jet recording head that performs recording on the recording sheet 1 by discharging ink from the recording head will be described. Reference numeral 8 denotes a platen that supports the back surface of the recording sheet 1 at a position facing the recording head 7. Reference numeral 10 denotes a carriage on which the recording head 7 is mounted and moves in a direction intersecting the sheet conveying direction.

  Reference numeral 9 denotes a discharge roller for discharging the recording sheet on which recording has been performed by the recording head 7 to the outside of the apparatus. Reference numerals 12 and 13 denote spurs that rotate in contact with the recording surface of the recording sheet on which recording has been performed by the recording head 7. Here, the spur 13 on the downstream side is urged toward the discharge roller 9, and the spur 12 on the upstream side is not provided with the discharge roller 9 at a position facing the spur 12. The spur 12 is for preventing the recording sheet 1 from rising, and is also called a holding spur.

  Between the feeding nip formed by the feeding roller 3 and the feeding driven roller 4 and the feeding nip formed by the feeding roller 5 and the pinch roller 6, the recording sheet 1 is transported by the feeding guide 15 and the flapper 20. You will be guided. The flapper 20 is rotatable by the reaction force of the recording sheet 1 conveyed by the feeding roller 3. Reference numeral 16 denotes a sheet detection sensor for detecting the leading edge and the trailing edge of the recording sheet 1. The sheet detection sensor 16 is provided downstream of the feeding roller 3 in the sheet conveyance direction. Reference numeral 17 denotes a sheet holding lever for overlapping the leading edge of the succeeding sheet with the trailing edge of the preceding sheet. With the state of ST1 in FIG. 1 as a neutral point, the first lever portion 17A is biased by a spring around the rotation shaft 17b in the counterclockwise direction in the drawing, and the tip of the first lever portion 17A The second lever portion 17B, that is, the tip portion 17c of the second lever portion 17B that comes into contact with the recording sheet 1 is urged by a spring around the rotation shaft 17a clockwise in the drawing. Reference numeral 22 denotes a sheet detection sensor for detecting the leading end and the trailing end of the recording sheet 1. The sheet detection sensor 22 detects the timing of the leading edge of the recording sheet 1 entering the transport nip formed by the transport roller 5 and the pinch roller 6, and the timing of the trailing edge of the recording sheet 1 during the recording operation. . Reference numeral 21 denotes a reversing guide member that constitutes a reversing mechanism for reversing the front and back of the recording sheet 1. The reversing guide member 21 guides the recording sheet 1 conveyed backward by the conveying roller 5 to the feeding nip portion of the feeding roller 3 and the feeding driven roller 4.

  FIG. 4 is a diagram illustrating the configuration of the pickup roller 2. As described above, the pickup roller 2 comes into contact with the uppermost recording sheet stacked on the feed tray 11 and picks up the recording sheet. Reference numeral 19 denotes a drive shaft for transmitting the drive of a feeding motor described later to the pickup roller 2. When picking up a recording sheet, the drive shaft 19 and the pickup roller 2 rotate in the direction of arrow A in the figure. The drive shaft 19 is provided with a projection 19a. The pickup roller 2 has a concave portion 2c into which the protrusion 19a is fitted. As shown in FIG. 4A, when the protrusion 19a is in contact with the first surface 2a of the concave portion 2c of the pickup roller 2, the drive of the drive shaft 19 is transmitted to the pickup roller 2, and the drive shaft 19 is driven. When driven, the pickup roller 2 is also rotated. On the other hand, as shown in FIG. 4B, when the protrusion 19a is in contact with the second surface 2b of the concave portion 2c of the pickup roller 2, the drive of the drive shaft 19 is not transmitted to the pickup roller 2, and Even if the shaft 19 is driven, the pickup roller 2 is not rotated. Even when the projection 19a is not in contact with either the first surface 2a or the second surface 2b and is located between the first surface 2a and the second surface 2b, the pickup is driven even when the drive shaft 19 is driven. The roller 2 is not rotated.

  FIG. 5 is a block diagram of the recording apparatus of the present embodiment. An MPU 201 controls the operation of each unit, data processing, and the like. As described later, the MPU 201 also functions as a conveyance control unit that can control conveyance of the recording sheet so that the rear end of the preceding recording sheet and the front end of the subsequent sheet overlap. A ROM 202 stores programs and data executed by the MPU 201. A RAM 203 temporarily stores processing data executed by the MPU 201 and data received from the host computer 214.

  The recording head 7 is controlled by a recording head driver 207. A carriage motor 204 for driving the carriage 10 is controlled by a carriage motor driver 208. The transport roller 5 and the discharge roller 9 are driven by a transport motor 205. The transport motor 205 is controlled by the transport motor driver 209. The pickup roller 2 and the feed roller 3 are driven by a feed motor 206. The feed motor 206 is controlled by a feed motor driver 210.

  The host computer 214 is provided with a printer driver 2141 for collecting print information such as print images and print image quality and communicating with a print apparatus when a print operation is instructed by a user. The MPU 201 exchanges a recorded image with the host computer 214 via the I / F unit 213.

  With reference to ST1 of FIG. 1 to ST9 of FIG. 3, the operation of the continuous continuous feeding in the continuous printing on only one side (front side) will be described in time series. When recording data is transmitted from the host computer 214 via the I / F unit 213, the recording data is processed by the MPU 201 and then expanded on the RAM 203. The MPU 201 starts a recording operation based on the developed data.

  In FIG. 1, in ST1, the feed motor 206 is first driven at a low speed by the feed motor driver 210. Thus, the pickup roller 2 is rotated at 7.6 inches / sec. When the pickup roller 2 rotates, the uppermost recording sheet (preceding sheet 1-A) stacked on the feed tray 11 is picked up. The preceding sheet 1-A picked up by the pickup roller 2 is conveyed by a feeding roller 3 rotating in the same direction as the pickup roller 2. The feed roller 3 is also driven by the feed motor 206. This embodiment will be described with a configuration including a pickup roller 2 and a feeding roller 3. However, a configuration in which only the feeding roller that feeds the recording sheets stacked on the stacking unit may be provided.

  When the leading end of the preceding sheet 1-A is detected by the sheet detection sensor 16 provided on the downstream side of the feeding roller 3, the feeding motor 206 is switched to high-speed driving. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec.

  In ST2, the leading end of the preceding sheet 1-A pushes up the flapper 20 against its own weight by continuing to rotate the feeding roller 3, and furthermore, rotates the sheet holding lever 17 on the rotating shaft against the urging force of the spring. Rotate clockwise around 17b. When the feeding roller 3 is further rotated, the leading end of the preceding sheet 1-A abuts on a transport nip formed by the transport roller 5 and the pinch roller 6. At this time, the transport roller 5 is in a stopped state. By rotating the feed roller 3 by a predetermined amount even after the leading edge of the preceding sheet 1-A has hit the transport nip portion, the leading sheet 1-A is aligned with the leading edge of the preceding sheet 1-A hitting the transport nip portion, and the skew is corrected. Is done. The skew correction operation is also called a registration operation.

  In ST3, when the skew correcting operation of the preceding sheet 1-A is completed, the conveying roller 205 starts rotating by driving the conveying motor 205. The transport roller 5 transports the sheet at 15 inches / sec. After the preceding sheet 1-A is caught to the position facing the recording head 7, a recording operation is performed by discharging ink from the recording head 7 based on the recording data. In the cueing operation, the leading edge of the recording sheet is once positioned at the position of the transport roller 5 by being abutted against the transport nip portion, and then the rotation amount of the transport roller 5 is controlled based on the position of the transport roller 5. It is performed by

  The recording apparatus according to the present embodiment is a serial type recording apparatus in which a recording head 7 is mounted on a carriage 10, and a conveyance operation of intermittently conveying a recording sheet by a predetermined amount by a conveyance roller 5, and the conveyance roller 5 stops. The image forming operation of ejecting ink from the recording head 7 while moving the carriage 10 on which the recording head 7 is mounted during the operation is repeated, thereby performing the recording operation on the recording sheet.

  When the preceding sheet 1-A is located, the feeding motor 206 is switched to low-speed driving. That is, the pickup roller 2 and the feed roller 3 rotate at 7.6 inch / sec. When the recording sheet is intermittently conveyed by a predetermined amount by the conveying roller 5, the feeding roller 3 is also intermittently driven by the feeding motor 206. That is, when the transport roller 5 is rotating, the feed roller 3 is also rotating, and when the transport roller 5 is stopped, the feed roller 3 is also stopped. The rotation speed of the feed roller 3 is lower than the rotation speed of the transport roller 5. Therefore, the sheet is stretched between the transport roller 5 and the feed roller 3. The feed roller 3 is rotated by the recording sheet conveyed by the conveying roller 5.

  To drive the feed motor 206 intermittently, the drive shaft 19 is also driven. As described above, the rotation speed of the pickup roller 2 is lower than the rotation speed of the transport roller 5. Therefore, the pickup roller 2 is rotated by the recording sheet transported by the transport roller 5. That is, the pickup roller 2 is in a state of being advanced with respect to the drive shaft 19. Specifically, the projection 19a of the drive shaft 19 is separated from the first surface 2a and is in contact with the second surface 2b. Therefore, even if the rear end of the preceding sheet 1-A passes through the pickup roller 2, the second recording sheet (the succeeding sheet 1-B) is not immediately picked up. When the drive shaft 19 is driven for a predetermined time, the protrusion 19a comes into contact with the first surface 2a, and the pickup roller 2 starts rotating.

  In FIG. 2, ST4 shows a state in which the pickup roller 2 starts rotating and the succeeding sheet 1-B is picked up. The sheet detection sensor 16 needs a predetermined interval or more between the sheets in order to detect the edge of the recording sheet due to factors such as the responsiveness of the sensor. That is, after the rear end of the preceding sheet 1-A is detected by the sheet detection sensor 16, the rear end of the preceding sheet 1-A is provided with a predetermined time interval until the leading end of the succeeding sheet 1-B is detected. It is necessary to keep a predetermined distance from the leading end of the succeeding sheet 1-B. Therefore, the angle range θ of the concave portion 2c of the pickup roller 2 is set to about 70 degrees.

  In ST5, the succeeding sheet 1-B picked up by the pickup roller 2 is conveyed by the feed roller 3. At this time, the image forming operation of the preceding sheet 1-A is performed by the recording head 7 based on the recording data. When the leading edge of the succeeding sheet 1-B is detected by the sheet detection sensor 16, the feeding motor 206 is switched to high-speed driving. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec.

  In ST6, the rear end of the preceding sheet 1-A is pushed down by the front end 17c of the second lever 17B of the sheet holding lever 17 as shown in ST5 of FIG. By moving the succeeding sheet 1-B at a high speed with respect to the speed at which the preceding sheet 1-A moves downstream due to the recording operation by the recording head 7, the succeeding sheet 1-A is placed on the rear end of the preceding sheet 1-A. A state where the tips overlap can be formed (ST6 in FIG. 2). Since the preceding sheet 1-A performs a recording operation based on the recording data, the preceding sheet 1-A is intermittently conveyed by the conveying rollers 5. On the other hand, the trailing sheet 1-B can catch up with the preceding sheet 1-A by continuously rotating the feed roller 3 at 20 inches / sec after the leading end is detected by the sheet detection sensor 16.

  In FIG. 3, in ST7, after forming an overlapping state in which the leading edge of the succeeding sheet 1-B overlaps the trailing edge of the preceding sheet 1-A, the leading edge of the succeeding sheet 1-B is at a predetermined position upstream of the transport nip. It is conveyed by the feed roller 3 until it stops. The position of the leading end of the succeeding sheet 1-B is calculated from the rotation amount of the feed roller 3 after the leading end of the succeeding sheet 1-B is detected by the sheet detection sensor 16, and is controlled based on the calculation result. At this time, an image forming operation is being performed on the preceding sheet 1-A by the recording head 7 based on the recording data.

  In ST8, when the transport roller 5 is stopped to perform the image forming operation (ink ejection operation) of the last line of the preceding sheet 1-A, the feeding roller 3 is driven to drive the succeeding sheet 1-B. The skew correcting operation of the succeeding sheet 1-B is performed by abutting the leading end against the transport nip portion.

  In ST9, when the image forming operation of the last line of the preceding sheet 1-A is completed, the state in which the succeeding sheet 1-B overlaps the preceding sheet 1-A by rotating the transport roller 5 by a predetermined amount. The cue of the succeeding sheet 1-B can be performed. A recording operation is performed on the succeeding sheet 1-B by the recording head 7 based on the recording data. When the succeeding sheet 1-B is intermittently conveyed for the printing operation, the preceding sheet 1-A is also intermittently conveyed, and the preceding sheet 1-A is discharged to the outside of the recording apparatus by the discharge roller 9 soon.

  When the succeeding sheet 1-B is located, the feeding motor 206 is switched to low-speed driving. That is, the pickup roller 2 and the feed roller 3 rotate at 7.6 inch / sec. If there is recording data after the succeeding sheet 1-B, the process returns to ST4 in FIG. 2 and the third sheet pickup operation is performed.

  FIG. 6 shows an overlapping continuous feeding sequence in continuous printing on only one side.

  In step S1, when recording data is transmitted from the host computer 214 via the I / F unit 213, the recording operation is started. In step S2, the feeding operation of the preceding sheet 1-A is started. Specifically, the feeding motor 206 is driven at a low speed. The pickup roller 2 rotates at 7.6 inches / sec. The preceding sheet 1-A is picked up by the pickup roller 2, and the preceding sheet 1-A is fed toward the recording head 7 by the feeding roller 3.

  In step S3, the process waits for the leading edge of the preceding sheet 1-A to be detected by the sheet detecting sensor 16, and when the leading edge of the preceding sheet 1-A is detected by the sheet detecting sensor 16, in step S4 the feeding motor 206 is switched to high-speed driving. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. Further, by controlling the rotation amount of the feed roller 3 after the leading end of the preceding sheet 1-A is detected by the sheet detecting sensor 16, the leading end of the leading sheet 1-A is moved to the transport nip in step S5. The skew correction operation of the preceding sheet 1-A is performed by abutment.

  In step S6, the preceding sheet 1-A is caught based on the recording data. That is, by controlling the rotation amount of the transport roller 5, the preceding sheet 1-A is transported to a recording start position based on the position of the transport roller 5 based on the print data. In step S7, the feeding motor 206 is switched to low-speed driving. In step S8, the recording operation is started by discharging ink from the recording head 7 to the preceding sheet 1-A. Specifically, by repeating a transport operation of intermittently transporting the preceding sheet 1-A by the transport roller 5 and an image forming operation (ink discharge operation) of discharging ink from the recording head 7 by moving the carriage 10, The recording operation for the preceding sheet 1-A is performed. The feeding motor 206 is intermittently driven at a low speed in synchronization with the operation of intermittently conveying the preceding sheet 1-A by the conveying roller 5. That is, the pickup roller 2 and the feed roller 3 rotate intermittently at 7.6 inch / sec.

  In step S9, it is determined whether there is recording data for the next page. If there is no recording data for the next page, the process proceeds to step S27. In step S27, when the recording operation on the preceding sheet 1-A is completed, the preceding sheet 1-A is discharged in step S28, and the recording operation ends.

  On the other hand, if there is print data of the next page in step S9, the feeding operation of the succeeding sheet 1-B is started in step S10. Specifically, the succeeding sheet 1-B is picked up by the pickup roller 2, and the succeeding sheet 1-B is fed toward the recording head 7 by the feeding roller 3. The pickup roller 2 rotates at 7.6 inches / sec. As described above, since the concave portion 2c of the pickup roller 2 is provided to be larger than the protrusion 19a of the drive shaft 19, the succeeding sheet 1-B has a predetermined distance from the rear end of the preceding sheet 1-A. Sent in state.

  In step S11, the process waits for the leading edge of the succeeding sheet 1-B to be detected by the sheet detecting sensor 16, and when the leading edge of the succeeding sheet 1-B is detected by the sheet detecting sensor 16, the feeding motor 206 in step S12. To high-speed drive. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. By controlling the amount of rotation of the feed roller 3 after the leading end of the succeeding sheet 1-B is detected by the sheet detection sensor 16, in step S13, the leading end of the succeeding sheet 1-B is moved by a predetermined amount in the transport nip. The subsequent sheet 1-B is conveyed so as to be located at the front. The preceding sheet 1-A is intermittently conveyed based on the recording data. For the succeeding sheet 1-B, the feeding motor 206 is continuously driven at a high speed, so that an overlapping state in which the leading end of the succeeding sheet 1-B overlaps the trailing end of the preceding sheet 1-A.

  In step S14, it is determined whether or not the leading end of the succeeding sheet 1-B has reached a specified position (P3 in ST5 in FIG. 8 described later). Cue. Specifically, when the image forming operation of the last line of the preceding sheet 1-A is completed in step S29, the discharging operation of the preceding sheet 1-A is performed in step S30. During this time, since the feed motor 206 is not driven, the leading end of the succeeding sheet 1-B is stopped at a position a predetermined distance before the transport nip. Since the preceding sheet 1-A is discharged, the overlapping state is eliminated. In step S31, the leading end of the succeeding sheet 1-B is abutted against the transport nip to perform the skew correcting operation of the succeeding sheet 1-B, and in step S35, the cueing of the succeeding sheet 1-B is performed.

  On the other hand, if the succeeding sheet 1-B has reached the specified position in step S14, the overlap amount is calculated in step S15. Thereafter, the processing differs depending on the presence or absence of the overlap reduction amount calculated in the overlap amount calculation processing. In step S16, the presence or absence of the overlap reduction amount is determined. If there is no overlap reduction amount, the skew correcting operation of the succeeding sheet 1-B can be performed during the image forming operation of the last line of the preceding sheet 1-A. Therefore, the process proceeds to step S32. In step S32, the process waits for the start of the image forming operation of the preceding sheet 1-A. In step S33, the skew correcting operation of the succeeding sheet 1-B is performed by abutting the leading end of the succeeding sheet 1-B against the transport nip while maintaining the overlapping state. In step S34, it is determined whether or not the image forming operation of the last line of the preceding sheet 1-A has been completed. If the image forming operation has been completed, in step S35, cueing of the succeeding sheet 1-B is performed while maintaining the overlapping state.

  On the other hand, if there is an overlap reduction amount in step S16, the process waits for the end of the last line image forming operation of the preceding sheet 1-A in step S17. When the last-line image forming operation of the preceding sheet 1-A is completed, the process proceeds to step S18, and the preceding sheet 1-A is transported to a predetermined position by the transport roller 5 so as to have an overlapping amount described later. In step S19, the leading end of the succeeding sheet 1-B is abutted against the transport nip to perform the skew correcting operation of the succeeding sheet 1-B, and then, in step S35, the cueing of the succeeding sheet 1-B is performed.

  In step S36, the feeding motor 206 is switched to low-speed driving. In step S37, the recording operation is started by discharging ink from the recording head 7 to the succeeding sheet 1-B. Specifically, by repeating a transport operation of intermittently transporting the subsequent sheet 1-B by the transport roller 5 and an image forming operation (ink discharging operation) of discharging ink from the recording head 7 by moving the carriage 10, The recording operation for the succeeding sheet 1-B is performed. The feeding motor 206 is intermittently driven at a low speed in synchronization with the operation of intermittently conveying the succeeding sheet 1-B by the conveying roller 5. That is, the pickup roller 2 and the feed roller 3 rotate intermittently at 7.6 inch / sec.

  In step S38, it is determined whether there is print data of the next page. If there is print data of the next page, the process returns to step S10. If there is no print data of the next page, image formation of the succeeding sheet 1-B is performed in step S39. Wait for the operation to complete. When the image forming operation is completed, the succeeding sheet 1-B is discharged in step S40, and the recording operation ends in step S41.

  FIG. 7 and FIG. 8 are diagrams illustrating the operation of superimposing the succeeding sheet on the preceding sheet in the present embodiment. The operation of forming the overlapping state in which the leading edge of the succeeding sheet is overlapped on the trailing edge of the preceding sheet, described in steps S12 and S13 in FIG.

  FIGS. 7 and 8 are enlarged views of a feeding nip formed by the feeding roller 3 and the feeding pinch roller 4 and a feeding nip formed by the feeding roller 5 and the pinch roller 6.

  The process in which the recording sheet is transported by the transport roller 5 and the feed roller 3 will be sequentially described as three states.

  First, a first state in which the succeeding sheet follows the preceding sheet will be described with reference to ST1 and ST2 in FIG. Next, a second state in which the succeeding sheet is overlapped with the preceding sheet will be described with reference to ST3 and ST4 in FIG. Then, a third state in which it is determined whether or not to perform the skew correcting operation on the succeeding sheet while maintaining the overlapping state will be described with reference to ST5 in FIG.

  7, in ST1, the feeding roller 3 is controlled to convey the succeeding sheet 1-B, and the sheet detection sensor 16 detects the leading end of the succeeding sheet 1-B. A section from the sheet detection sensor 16 to a position P1 at which the succeeding sheet 1-B can be superimposed on the preceding sheet 1-A is defined as a first section A1. In the first section A1, the leading edge of the succeeding sheet 1-B follows the trailing edge of the preceding sheet 1-A. P1 is determined by the structure of the mechanism.

  In the first state, there is a case where the chase operation is stopped in the first section A1. When the leading edge of the succeeding sheet 1-B passes the trailing edge of the preceding sheet 1-A before P1, as in ST2 of FIG. 7, the operation of superimposing the succeeding sheet on the preceding sheet is not performed.

  In FIG. 8, in ST3, a section from the above-described P1 to a position P2 where the sheet holding lever 17 is provided is defined as a second section A2. In the second section A2, an operation of superimposing the succeeding sheet 1-B on the preceding sheet 1-A is performed.

  In the second state, there is a case where the operation of overlapping the succeeding sheet on the preceding sheet is stopped in the second section A2. When the leading end of the succeeding sheet 1-B cannot catch up with the trailing end of the preceding sheet 1-A in the second section A2 as in ST4 of FIG. 8, the operation of superimposing the preceding sheet on the succeeding sheet cannot be performed.

  In ST5, the above-mentioned P2 to P3 is defined as a third section A3. P3 is the position of the leading edge when the succeeding sheet stops in step S13 in FIG. With the succeeding sheet 1-B superimposed on the preceding sheet 1-A, the sheet is conveyed until the leading end of the succeeding sheet 1-B reaches P3. In the third section A3, it is determined whether or not cueing is performed by abutting the succeeding sheet 1-B against the transport nip while maintaining the overlapping state. That is, it is determined whether the skew correction operation is performed while maintaining the overlapping state to perform cueing, or the skew correction operation is performed after canceling the overlapping state to perform cueing.

  Next, a process of determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B will be described with reference to FIGS.

  FIG. 9 shows the overlap amount calculation processing in step S15 of FIG. 6, and FIGS. 10 and 11 show the processing of calculating the overlap reduction amount Y (B) depending on the succeeding sheet 1-B in step S908 of FIG. FIG. 12 is a schematic diagram showing an overlap area of a recording sheet, FIG. 13 is a schematic view showing cockling of a succeeding sheet superimposed on a preceding sheet, and FIG. 14 is a diagram of a recording density detection area division on the succeeding sheet 1-B. FIG.

  The sheet size of the preceding sheet 1-A is acquired from the recording information of the preceding sheet 1-A transmitted from the host computer 214, and the length Lp (A) of the preceding sheet 1-A in the transport direction is acquired (step S901). . Further, a write start position Lu (A) and a data length Ld (A) of data to be recorded on the preceding sheet 1-A are obtained from the recording information (steps S902 and S903). As shown in FIG. 12, the trailing margin Lmax (A) of the preceding sheet 1-A is determined based on the length Lp (A) of the preceding sheet 1-A, the writing position Lu (A), and the recording data length Ld (A). Can be calculated. A value obtained by subtracting a predetermined overlapping margin X (0) in consideration of the overlapping accuracy of the feeding roller 3 and the conveying roller 5 from the trailing edge margin Lmax (A) is determined as the overlapping amount (based on the preceding sheet 1-A). (Overlapping amount) Lb (A) (step S904). Here, from the viewpoint of simplicity of description, the recording data length Ld (A) is obtained at the start of recording of the preceding sheet 1-A. The length Ld (A) may be obtained.

  On the other hand, there is an upper limit LM of the overlapped distance mechanically due to the transport path sandwiched by the transport guide 15 and the arrangement of the transport roller 5 and the feed roller 3. Therefore, the preceding sheet-based overlapping amount Lb (A) calculated from the recording data is compared with the upper limit LM of the overlapping distance, and if the upper limit LM is smaller, the preceding sheet-based overlapping amount Lb (A) is set to the value of LM. (Steps S905 and S906).

  Next, a process of calculating the overlap reduction amount (the succeeding sheet-induced overlap reduction amount) Y (B) depending on the succeeding sheet 1-B is performed.

  In step S907, a writing start position Lu (B) of data to be recorded on the succeeding sheet 1-B is obtained from the recording information of the succeeding sheet 1-B transmitted from the host computer 214.

  In step S908, the subsequent sheet-based reduction amount Y (B) is calculated. When performing the printing operation (overprinting) by superimposing the succeeding sheet 1-B on the preceding sheet 1-A, as shown in FIG. 13, the succeeding sheet 1-B is not located immediately above the platen rib 8a, but in a blank area and the platen rib 8a. The preceding sheet 1-A exists between the two. The back surface of the succeeding sheet 1-B is restrained by the preceding sheet 1-A instead of the platen rib 8a. Therefore, when the recording density at the leading end of the succeeding sheet is high, the succeeding sheet 1-B is reduced by the cocking deformation height. B approaches the recording head 7. Therefore, if the deformation height due to cockling is large and the succeeding sheet 1-B and the recording head 7 may be rubbed, it is necessary to set the succeeding sheet-induced overlap reduction amount Y (B) so as to avoid overprinting. .

  Here, the details of the process of calculating the subsequent sheet-induced overlap reduction amount Y (B) in step S908 in FIG. 9 will be described with reference to FIG.

  In step S1001, the print density detection area LDA () of the succeeding sheet 1-B is determined based on the preceding sheet-based overlapping amount Lb (A) already calculated and the write start position Lu (B) of the data to be printed on the succeeding sheet 1-B. B) is obtained.

  In step S1002, in order to facilitate the recording density detection processing, the rounding processing is performed so that the recording density detection area LDA (B) is m times (m is an integer) the distance L0 in the transport direction of the unit area. Here, it is assumed that m = 3. As shown in FIG. 14, the recording density detection area is divided into a (1), a (2), and a (3) (step S1003). Then, the print density da (i) of the print area a (i) is calculated (step S1004).

  The recording density da (i) is obtained from the number of ink ejection dots in a unit area in a predetermined recording density detection area. Although the ink discharge amount varies depending on the nozzle diameter, a large dot of color (cyan, magenta, yellow) is defined as a reference (= 1), a small dot of color is defined as a standard × １ ／, and a black is defined as a standard × 2. In the present embodiment, 600 dpi is defined as one pixel, and the recording density when the ink amount per pixel is the reference × 2 is defined as 100%. As shown in FIG. 14, in this embodiment, the distance in the transport direction (sub-scanning direction) of the unit area is L0, the distance in the scanning direction (main scanning direction) of the recording head 7 orthogonal to the transport direction is W0, and L0 Is 256 pixels and W0 is 640 pixels. The recording density D is calculated from the average ink amount per block of 1 × 1 pixel in this unit area.

  FIG. 11 shows details of the recording density detection processing in step S1004 of FIG. First, the maximum value Dmax of the recording density is set to an initial value (S1101), and the recording density D in the detected unit area is sequentially acquired in the recording density detection area a (1) (step S1102). Next, a comparison is made with the already obtained maximum value Dmax of the recording density D (step S1103), and the maximum value Dmax is updated (step S1104). Then, the processing of steps S1102 to S1104 is repeated for each detection area (step S1105), and the finally remaining recording density Dmax is set as the recording density da (1) in the recording density detection area a (1) (step S1106). . Similarly, in the areas a (2) and a (3), the recording densities da (2) and da (3) are detected, respectively.

  The threshold value of the predetermined recording density is d0, and the threshold value d0 is compared with the recording densities da (1) to da (3). FIG. 15 shows the threshold value d0 of the recording density, and the threshold value d0 is set so as to decrease as the number of printing passes (the number of scans of the recording head) in image formation increases. This is because the recording time varies depending on the number of printing passes, and the longer the recording time, the greater the amount of deformation of the recording sheet due to cockling.

Returning to FIG. 10, comparison is performed from the region a (1) on the front end side, and when the threshold value d0 is exceeded, overlapping is disabled from that region. First, the recording density da (1) is compared with a threshold value d0 in order to determine whether or not the area a (1) can be overlapped (step S1005). When the recording density da (1) exceeds the threshold value d0, the area a (1) cannot be overlapped and the succeeding sheet-induced overlap reduction amount Y (B) is calculated as follows: Y (B) = m · L0 = 3 × L0
Is set (step S1006), and the process ends.

  On the other hand, if the recording density da (1) is equal to or smaller than the threshold value d0 in step S1005, the area a (1) is allowed to be overlapped, and the process proceeds to the area a (2) overlap possibility determination processing. In step S1007, it is determined whether or not the area a (2) can be overlapped in the same manner as in the area a (1). If the overlap is not possible, the subsequent sheet-based overlap reduction amount Y (B) is calculated (step S1008), and the process ends. . If the overlap is possible, the process proceeds to the determination of the overlap possibility of the area a (3). In step S1009, it is similarly determined whether the area a (3) can be overlapped. If the area cannot be overlapped, the subsequent sheet-based overlap reduction amount Y (B) is calculated (step S1010), and the process ends. If the overlap is permitted, the entire determination area is permitted to be overlapped. Therefore, the succeeding sheet-based overlap reduction amount Y (B) is set to zero (step S1011), and the process ends.

  The final overlap amount Lt (B) is calculated from the succeeding sheet-based overlap amount Y (B) obtained as described above and the previously calculated preceding sheet-based overlap amount Lb (A) (FIG. 9). Step S909).

  In the process of calculating the overlap amount Lt (B) in FIG. 9, the subsequent sheet-induced reduction amount Y (B) is calculated based on the recording densities da (1) to da (3) as described with reference to FIGS. The deformation amount of the succeeding sheet 1-B is estimated based on each of the print densities da (1) to da (3) and other printing conditions (the number of printing passes or the time required for printing). Y (B) may be obtained based on the amount of deformation.

  In the above-described processing for calculating the overlap amount Lt (B), the threshold value of the recording density is changed according to the number of printing passes in image formation. However, when the number of printing passes is large, the image quality priority mode is set. The superposition operation may not be performed.

  If the succeeding sheet-based overlap reduction amount Y (B) is zero, the trailing margin amount of the preceding sheet 1-A except for the predetermined overlap margin X (0) is eventually overlapped, but is always a fixed amount. In the case where the trailing margin amount is overlapped in consideration of the overlap margin, the present invention is not included in the present invention.

  In the present embodiment, an area where printing is not performed at the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is defined as a margin. Included in the invention.

  According to the above-described embodiment, it is possible to suppress sheet contamination, paper jam, deterioration in image quality, and the like, which occur when a high-density printing is performed by superimposing a succeeding sheet on a preceding sheet, thereby increasing printing speed. Becomes

  [Second Embodiment] Next, with reference to FIGS. 16 to 23, a description will be given of a process of determining a preceding sheet-induced overlap amount Lb (A) according to a second embodiment.

  Note that the device configuration of the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

  FIG. 16 illustrates a process of calculating the preceding sheet-induced overlap amount Lb (A) according to the present embodiment.

  As in steps S901 to S903 in FIG. 9, the length Lp (A) of the preceding sheet 1-A, the write start position Lu (A) of the recording data, and the recording information of the preceding sheet 1-A transmitted from the host computer 214. And the data length Ld (A) is obtained (steps S1601 to S1603).

  In step S1604, the trailing margin of the preceding sheet 1-A is calculated from the acquired length Lp (A) of the preceding sheet 1-A, the writing position Lu (A), and the data length Ld (A), and the maximum overlap amount is calculated. Lmax (A).

  In step S1605, the overlap reduction amount (preceding sheet-induced overlap reduction amount) X (A) that depends on the preceding sheet 1-A is calculated. When the recording density at the rear end of the preceding sheet 1-A is high, deformation due to cockling occurs near the rear end including the blank area as shown in FIG. 17, and the deformed blank area is formed from the platen rib 8a as shown in FIG. May float slightly. In this case, when the succeeding sheet 1-B is overlaid on the preceding sheet 1-A, the succeeding sheet 1-B approaches the recording head 7 as compared with the attitude 1-Ba of the succeeding sheet 1-B when not overlapping. Will be. It is necessary to set the preceding sheet-induced overlap reduction amount X (A) so as not to be affected by the deformation near the rear end of the preceding sheet 1-A.

  FIG. 19 shows details of the processing for calculating the preceding sheet-induced overlap reduction amount X (A) in step S1605 in FIG.

  As shown in FIG. 20, the preceding sheet-induced overlap reduction amount X (A) is set according to the recording density of the preceding sheet 1-A, and is set from the last position of the print data of the preceding sheet 1-A to the next succeeding sheet. This is the margin distance provided up to the sheet leading edge position 1-B. In the final margin distance provided from the final position of the print data of the preceding sheet 1-A to the leading end position of the next succeeding sheet 1-B, the succeeding sheet-based overlap reduction amount Y (B described in the first embodiment is used. ) May be added. In the present embodiment, a necessary preceding sheet-based overlap reduction amount X (A) is determined according to the recording density D of a predetermined recording density detection area.

  The recording density D is obtained from the number of ink ejection dots in a unit area in a predetermined recording density detection area. As shown in FIG. 21, in the present embodiment, the distance in the transport direction of the unit area is L0, the distance in the main scanning direction is W0, 600 dpi is 1 pixel, L0 is 256 pixels, and W0 is 640 pixels. The recording density detection area is an area within 1028 pixels in the transport direction from the trailing edge of the preceding sheet. In this print density detection area, the print density D is calculated from the average ink amount per block of 1 pixel × 1 pixel.

  In FIG. 19, the maximum value Dmax of the recording density is set to an initial value (S1901), the recording density D in the unit area obtained as described above is sequentially obtained (step S1902), and the maximum value of the recording density D already obtained is obtained. The value Dmax is compared with the value Dmax (step S1903), and the maximum value Dmax is updated (step S1904). Then, the processing of steps S1902 to S1905 is repeated for each recording density detection area, and the finally remaining recording density is set to Dmax.

  The preceding sheet-induced overlap reduction amount X (A) is obtained based on the detected recording density Dmax from the function F1 shown in FIG. 22 (step S1906). D1 and D2 shown in FIG. 22 are set to the values shown in FIG. 23 according to the number of print passes in image formation. Note that the preceding sheet-based overlap reduction amount X (A) has a lower limit value X0 based on the overlap accuracy of the feed roller 3 and the transport roller 5.

  From the preceding sheet-based overlap reduction amount X (A) and the maximum overlap amount Lmax (A) obtained as described above, the preceding sheet-based overlap amount Lb (A) is calculated (step S1606).

  On the other hand, there is an upper limit LM of the overlapped distance mechanically due to the transport path sandwiched by the transport guide 15 and the arrangement of the transport roller 5 and the feed roller 3. Therefore, the preceding sheet-based overlapping amount Lb (A) calculated from the recording data is compared with the upper limit LM of the overlapping distance, and if the upper limit LM is smaller, the preceding sheet-based overlapping amount Lb (A) is set to the value of LM. (Steps S1607 and S1608).

  As described above, the preceding sheet-based overlapping amount Lb (A) is calculated.

  According to the present embodiment, it is possible to suppress sheet contamination, paper jam, deterioration in image quality, and the like, which occur when a high-density printing is performed by superimposing a succeeding sheet on a preceding sheet and performing printing at high speed. Become.

  [Embodiment 3] Next, with reference to FIGS. 24 to 27, a process of determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B according to Embodiment 3 will be described.

  This embodiment determines the final overlap amount Lt (B) in consideration of the difference in the environmental conditions of temperature and humidity from the above-described first and second embodiments. ), The method of calculating the subsequent sheet-induced overlap reduction amount Y (B) is different.

  The device configuration of the present embodiment is the same as that of the first embodiment except that a temperature sensor and a humidity sensor (not shown) are provided.

  FIG. 24 illustrates a process of calculating the overlap amount Lt (B) according to the present embodiment.

  As in FIGS. 9 and 16, the length Lp (A) of the preceding sheet 1-A, the write start position Lu (A) of the recording data, and the data from the recording information of the preceding sheet 1-A transmitted from the host computer 214. The length Ld (A) is obtained (steps S2401 to S2403). The trailing margin of the preceding sheet 1-A is calculated from the acquired length Lp (A) of the preceding sheet 1-A, the writing position Lu (A), and the data length Ld (A), and the maximum overlap amount Lmax (A) (Step S2404).

  Next, the preceding sheet-induced overlap reduction amount X (A) is calculated (step S2405). Details of the process of calculating the preceding sheet-induced overlap reduction amount X (A) are substantially the same as those in FIG. In other words, the preceding sheet-induced overlap reduction amount X (A) is set according to the recording density of the preceding sheet 1-A, and is set from the last position of the recording data of the preceding sheet 1-A to the next succeeding sheet 1-B. This is the margin distance provided up to the leading end position (see FIG. 25). The margin distance provided from the final position of the recording data of the preceding sheet 1-A to the leading end position of the next succeeding sheet 1-B is added to the succeeding sheet-induced overlap reduction amount Y (B) described later. You. In the present embodiment, the necessary preceding sheet-based overlap reduction amount X (A) is determined according to the recording density of a predetermined recording density detection area.

  As described with reference to FIG. 19, the processing of steps S1902 to S1905 is repeated for each recording density detection area, and a final recording density Dmax is obtained. The preceding sheet-induced overlap reduction amount X (A) is obtained based on the recording density Dmax from the function F1 shown in FIG. 22 (step S1906). FIG. 26 shows a table for obtaining the parameters t1, t2, h1, h2, p1, and p2 used when calculating the variables D1, D2 shown in FIG. In FIG. 26, each parameter is provided for each of the environmental temperature and environmental humidity of the printing apparatus, the number of printing passes in one-pass printing in image formation, and the number of printing passes in a plurality of multi-pass printings, and based on these printing conditions. Select each applicable parameter. D01 and D02 are the values of the variables D1 and D2 under the reference recording conditions, and the variables D1 and D2 under each recording condition are calculated from the following equations based on the reference values.

D1 = t1 * h1 * p1 * D01
D2 = t2 * h2 * p2 * D02
That is, the function for obtaining the preceding sheet-induced overlap reduction amount X (A) can be changed according to the recording conditions of the environmental temperature, the environmental humidity, and the number of print passes. Note that the preceding sheet-based overlap reduction amount X (A) has a lower limit value X0 based on the overlap accuracy of the feed roller 3 and the transport roller 5.

  From the preceding sheet-induced overlap reduction amount X (A) and the maximum overlap amount Lmax (A) determined as described above, the preceding sheet-induced overlap amount Lb (A) is calculated (step S2406).

  On the other hand, there is an upper limit LM of the overlapped distance mechanically due to the transport path sandwiched by the transport guide 15 and the arrangement of the transport roller 5 and the feed roller 3. Therefore, the preceding sheet-based overlapping amount Lb (A) calculated from the recording data is compared with the upper limit LM of the overlapping distance, and if the upper limit LM is smaller, the preceding sheet-based overlapping amount Lb (A) is set to the value of LM. (Steps S2407 and S2408).

  Next, calculation processing of the succeeding sheet-induced overlap reduction amount Y (B) is performed.

  In step S2409, a write start position Lu (B) of data to be recorded on the succeeding sheet 1-B is acquired from the recording information of the succeeding sheet 1-B transmitted from the host computer 214.

  In step S2410, the succeeding sheet-induced overlap reduction amount Y (B) is calculated. The details of the process of calculating the subsequent sheet-induced overlap reduction amount Y (B) are substantially the same as those in FIG. That is, the recording densities da (1) to da (3) of the recording density detection areas a (1) to a (3) are detected in steps S1001 to S1004 described with reference to FIG.

  Further, the threshold value of the predetermined recording density is set to d0, and is compared with the recording densities da (1) to da (3). FIG. 27 shows a table for calculating parameters t3, h3, and p3 that are used for calculating the recording density threshold value d0 according to the environmental temperature, the environmental humidity, and the number of print passes in image formation. d00 is a reference value of d0 under the recording condition serving as a reference, and d0 under each recording condition is calculated from the following equation based on the reference value.

d0 = t3 * h3 * p3 * d00
Next, from the succeeding sheet-based overlap reduction amount Y (B) obtained in steps S1005 to S1011 of FIG. 10 and the previously calculated preceding sheet-based overlap amount Lb (A), the final overlap amount Lt (B) is obtained. ) Is calculated (step S2411).

  According to the above-described embodiment, sheet contamination, paper jam, deterioration in image quality, and the like, which occur when a high-density printing is performed by superimposing the succeeding sheet 1-B on the preceding sheet 1-A, are suppressed, Printing can be speeded up.

  [Fourth Embodiment] Next, a method of calculating the succeeding sheet-induced overlap reduction amount Y (B) of the fourth embodiment will be described with reference to FIG.

  This embodiment differs from Embodiment 3 in the method of calculating the subsequent sheet-induced overlap reduction amount Y (B) when determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B.

  The apparatus configuration of the present embodiment, the processing for determining the final overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B, and the processing for calculating the preceding sheet-induced overlap reduction amount X (A) are as follows. Since this is the same as Embodiment 1, the description is omitted.

  FIG. 28 illustrates a process of calculating the subsequent sheet-induced overlap reduction amount Y (B) according to the present embodiment.

  In steps S2801 to S2803, similarly to steps S1001 to S1003 in FIG. 10, the recording density detection area LDA (B) of the succeeding sheet 1-B is obtained, and the recording density detection area LDA (B) is set in the transport direction of the unit area. A round-up process is performed so as to be m times the distance L0 (m is an integer) (step S1002). Here, for convenience of explanation, m = 4, and the recording density detection area is divided into a (1), a (2), a (3), and a (4) (step S2803). Then, for the areas a (1) to a (4), the recording density is detected for each unit area divided by the width W0 in the main scanning direction, and the maximum value is determined as the recording densities da (1) to da (4). (Step S2804).

  In step S2805, DA (1) to DA (4) are defined and calculated as superimposability determination values for determining whether the regions a (1) to a (4) are superimposable. Then, in order to determine whether or not the corresponding area can be overlaid, a superimposability determination value is calculated from the following equation by going back to the recording density of two areas upstream of the corresponding area.

DA (n) = 0.25 * da (n-2) + 0.5 * da (n-1) + 1 * da (n)
Further, the threshold value of the predetermined recording density is set to DA0, and the threshold value is compared with the calculated overlap determination value. Similarly to the threshold value d0 of the third embodiment, the threshold value DA0 of the recording density is calculated from the parameters corresponding to the environmental temperature, the environmental humidity, the number of print passes in image formation, and the reference threshold value.

The comparison is performed from the region a (1) on the front end side, and when the threshold value DA0 is exceeded, the region cannot be overlapped. First, in order to determine whether or not the area a (1) can be overlaid, the overlappedness determination value DA (1) is compared with a threshold value DA0 (step S2806). If the superimposability determination value DA (1) exceeds the threshold value DA0, the area a (1) is not superimposable, and the subsequent sheet-induced superimposition reduction amount Y (B) is calculated as Y (B) = m · L0 = 4 × L0
Is set (step S2807), and the subsequent sheet-induced overlap reduction amount Y (B) calculation processing ends.

  On the other hand, when the overlap possibility determination value DA (1) is equal to or smaller than the threshold value DA0, the region a (1) is allowed to overlap, and the process proceeds to the overlap possibility determination of the region a (2). Hereinafter, in the same manner as in the area a (1), the overlap determination is performed in order from the area a (2). If the overlap is not possible, the subsequent sheet-based overlap reduction amount Y (B) is calculated (S2807). The process proceeds to the determination of whether the next area can be overlapped (step S2808). By repeating these processes in and after the region a (2), a final succeeding sheet-induced overlap reduction amount Y (B) is calculated (steps S2808 to S2814).

  The final overlap amount Lt (B) is calculated from the succeeding sheet-based overlap amount Y (B) obtained as described above and the preceding sheet-based overlap amount Lb (A) already calculated.

  According to the above-described embodiment, it is possible to suppress sheet contamination, paper jam, deterioration in image quality, and the like, which occur when a high-density printing is performed by superimposing a succeeding sheet on a preceding sheet, thereby increasing printing speed. Becomes

  [Embodiment 5] Next, with reference to FIGS. 29 to 35, an explanation will be given on the operation of continuous feeding in double-sided printing and the process of determining the preceding sheet-induced overlapping amount Lb (A) according to the fifth embodiment.

  Since the device configuration of the present embodiment is the same as that of the first embodiment, the description is omitted.

  With reference to ST11 of FIG. 29 to ST16 of FIG. 30, the operation of reversing the recording sheet in the double-sided printing mode will be described in time series. The printing operation on one side in the double-sided printing mode is the same as the operation from ST1 to ST3 in FIG.

  In FIG. 29, in ST11, when the printing operation of the preceding sheet 1-A ends, the rotations of the transport roller 5 and the discharge roller 9 stop. The trailing end of the preceding sheet 1-A rotates the transport roller 5 and the discharge roller 9 from the transport nip portion of the transport roller 5 and the pinch roller 6 to a position of a distance LA to remove the preceding sheet 1-A passing through the transport nip portion. It is held by the discharge roller 9 and the spur 13. At this time, the flapper 20 is at a position where it is lowered downward by its own weight as shown in the figure, and guides the preceding sheet 1-A to the reverse guide member 21.

  In ST12, the transport roller 5 and the discharge roller 9 rotate in the reverse direction (clockwise in the drawing) in the direction opposite to that during the recording operation, and re-enters the preceding sheet 1-A into the transport nip between the transport roller 5 and the pinch roller 6. The sheet is conveyed toward the conveyance guide 15 and the sheet holding lever 17. At this time, the transport roller 5 rotates at 8 inches / sec.

  In ST13, when the conveying roller 5 continues to rotate clockwise in the drawing, the end of the preceding sheet 1-A (the rear end at the time of printing on the front side) pushes the leading end 17c of the sheet pressing lever 17 against the urging force of the spring. It is rotated counterclockwise around the rotation axis 17a. Here, the sheet press lever 17 may be configured such that the end of the preceding sheet 1-A passes below the front end 17c of the sheet press lever 17 without contact. When the transport roller 5 continues to rotate, the end of the preceding sheet 1-A is guided to the reversing guide member 21.

  In FIG. 30, in ST14, when the transport roller 5 continues to rotate, the end of the preceding sheet 1-A (the rear end during front side printing) is guided by the reverse guide member 21, and the feed roller 3 and the feed driven roller 4 enters the feed nip. Further, when the sheet detection sensor 16 detects the end of the preceding sheet 1-A (the rear end at the time of front side printing), the rotation of the conveying roller 5 and the feeding roller 3 is stopped once when the conveying roller 5 rotates by a predetermined amount. I do. At this time, a transport path by the transport guide 15 and the reversing guide member 21 is configured so that the other end of the preceding sheet 1-A (the leading edge at the time of front surface printing) can be securely pulled out of the transport nip portion. Further, when the end of the preceding sheet 1-A (the rear end at the time of front side printing) reaches the front end 17c of the sheet press lever 17, the other end of the preceding sheet 1-A (the front end at the time of front side printing) is held at the sheet holding lever. It is configured so as to pass through the tip portion 17c of the 17.

  In ST15, by continuing to rotate the feed roller 3, the end of the preceding sheet 1-A (the rear end at the time of surface printing) pushes the flapper 20 up against its own weight and the reaction force of the preceding sheet 1-A, It joins the transport guide 15 again. At this time, since the other end of the preceding sheet 1-A (the leading end at the time of front side printing) is not in contact with the sheet holding lever 17, the end of the preceding sheet 1-A (the rear end at the time of front side printing) passes the flapper 20. The reaction force of the preceding sheet 1-A at the time of pushing up can be minimized. When the feeding roller 3 is further rotated, the end of the preceding sheet 1-A abuts on the transport nip formed by the transport roller 5 and the pinch roller 6, similarly to ST2 in FIG. Perform line correction.

  In ST16, when the skew correcting operation of the preceding sheet 1-A is completed, the conveyance roller 205 starts rotating by driving the conveyance motor 205. The transport roller 5 transports the sheet at 15 inches / sec. The preceding sheet 1-A is caught to the position facing the recording head 7, and at this time, the surface of the preceding sheet 1-A facing the recording head 7 is a blank sheet opposite to the surface on which recording has already been performed. It is on the back. The recording operation is performed by ejecting ink from the recording head 7 based on the recording data to the back surface of the preceding sheet 1-A for which cueing has been completed.

  When the recording operation of the back surface of the preceding sheet 1-A is started, the pickup operation of the succeeding sheet 1-B is started. This is the same as the continuous feeding operation in the single-sided continuous printing described in ST4 of FIG. 2 in the first embodiment.

  Thereafter, the overlapping continuous feeding operation of the back surface of the preceding sheet 1-A and the succeeding sheet 1-B up to ST9 in FIG.

  Next, with reference to FIGS. 31 and 32, a description will be given of a continuous continuous feeding sequence in double-sided printing.

  In step S3101, when print data is transmitted from the host computer 214 via the I / F unit 213, a print operation is started. In step S3102, H, the feeding operation of the preceding sheet 1-A is started. Specifically, the feeding motor 206 is driven at a low speed. The pickup roller 2 rotates at 7.6 inches / sec. The preceding sheet 1-A is picked up by the pickup roller 2, and the preceding sheet 1-A is fed toward the recording head 7 by the feeding roller 3.

  In step S3103, the leading end of the preceding sheet 1-A is detected by the sheet detection sensor 16. When the leading edge of the preceding sheet 1-A is detected by the sheet detection sensor 16, the feeding motor 206 is switched to high-speed driving in step S3104. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. By controlling the amount of rotation of the feed roller 3 after the leading edge of the preceding sheet 1-A is detected by the sheet detection sensor 16, the leading edge of the preceding sheet 1-A is brought into contact with the transport nip in step S3105. The skew correcting operation of the sheet 1-A is performed.

In step S3106, the preceding sheet 1-A is located on the basis of the print data. That is, by controlling the rotation amount of the transport roller 5, the preceding sheet 1-A is transported to a recording start position based on the position of the transport roller 5 based on the print data. In step S3107, the feeding motor 206 is switched to low-speed driving. In step S3108, a recording operation is started by discharging ink from the recording head 7 onto the surface of the preceding sheet 1-A. More specifically, by repeating a transport operation for intermittently transporting the preceding sheet 1-A by the transport roller 5 and an image forming operation (ink discharging operation) for discharging ink from the recording head 7 moved by the carriage 10, The recording operation on the surface of the preceding sheet 1-A is performed.
The feeding motor 206 is intermittently driven at a low speed in synchronization with the operation of intermittently conveying the preceding sheet 1-A by the conveying roller 5. That is, the pickup roller 2 and the feed roller 3 rotate intermittently at 7.6 inch / sec.

  In step S3109, the process waits for the completion of the recording operation on the front surface of the preceding sheet 1-A, and proceeds to step S3110 to convey the rear end of the preceding sheet 1-A to a predetermined position (LA in ST11 in FIG. 29). In step S3111, it is checked whether the recording sheet has a reversible sheet length. The sheet length of the preceding sheet 1-A is confirmed, and if the length is out of the predetermined range, the flow advances to step S3112 to discharge the preceding sheet 1-A, and the process ends. The sheet length of the preceding sheet 1-A is confirmed, and if the length is within the predetermined range, the process proceeds to step S3114 to wait for a predetermined time for drying.

  In step S3115, the reverse rotation of the transport roller 5 and the discharge roller 9 and the normal rotation of the feed roller 3 are started, and the reverse operation of the preceding sheet 1-A is performed. When the preceding sheet 1-A passes through the sheet detection sensor 16 in step S3116, the rotation of the transport roller 5, the discharge roller 9, and the feed roller 3 is stopped in step S3117. In step S3118, a drying wait is performed for a predetermined time. In step S3119, the feed roller 3 is rotated, and the preceding sheet 1-A is fed again toward the recording head 7.

  In step S3120, the process waits for the sheet detection sensor 22 to detect the leading end of the preceding sheet 1-A. Then, by controlling the amount of rotation of the feed roller 3 after the leading edge of the preceding sheet 1-A is detected, the leading edge of the preceding sheet 1-A is brought into contact with the transport nip portion to tilt the leading sheet 1-A. A line correcting operation is performed (step S3121).

  In step S3122, the preceding sheet 1-A is located on the basis of the recording data. In step S3123, the recording operation is started by discharging ink from the recording head 7 to the back surface of the preceding sheet 1-A.

  In step S3124, it is determined whether there is print data for the next page. If there is no print data for the next page, the process waits for completion of the printing operation on the preceding sheet 1-A in step S3126. 1-A is discharged, and the recording operation ends in step S3128.

  If there is print data for the next page in step S3124, the process advances to step S3125 to start the double-sided overlapping operation.

  FIG. 32 shows a double-sided overlapping operation sequence in step S3125 of FIG.

  If there is print data of the next page in step S3124, the feeding operation of the succeeding sheet 1-B is started in step S3201. Specifically, the succeeding sheet 1-B is picked up by the pickup roller 2, and the succeeding sheet 1-B is fed toward the recording head 7 by the feeding roller 3. The pickup roller 2 rotates at 7.6 inches / sec. As described above, since the concave portion 2c of the pickup roller 2 is provided so as to be larger than the protrusion 19a of the drive shaft 19, the succeeding sheet 1-B has a predetermined interval from the rear end of the back surface of the preceding sheet 1-A. Sent in a state where

  In step S3202, the leading end of the succeeding sheet 1-B is detected by the sheet detection sensor 16. When the leading edge of the succeeding sheet 1-B is detected by the sheet detection sensor 16, the feeding motor 206 is switched to high-speed driving in step S3203. That is, the pickup roller 2 and the feed roller 3 rotate at 20 inches / sec. By controlling the amount of rotation of the feed roller 3 after the leading edge of the succeeding sheet 1-B is detected by the sheet detection sensor 16, in step S3204, the leading edge of the succeeding sheet 1-B is located a predetermined distance before the transport nip. The subsequent sheet 1-B is conveyed so as to be at the position of. The back surface of the preceding sheet 1-A is intermittently conveyed based on the recording data. By continuously driving the feed motor 206 at a high speed in the succeeding sheet 1-B, an overlap state is formed in which the front end of the succeeding sheet 1-B overlaps the rear end of the back surface of the preceding sheet 1-A.

  In step S3205, it is determined whether the leading edge of the succeeding sheet 1-B has reached the specified position (P3 in ST5 in FIG. 8). If it has not reached here, the overlapping state is resolved and the succeeding sheet 1-B is searched. Specifically, when the image forming operation of the last line on the back surface of the preceding sheet 1-A is completed in step S3211, the discharging operation of the back surface of the preceding sheet 1-A is performed in step S3212. During this time, since the feed motor 206 is not driven, the front surface of the succeeding sheet 1-B is stopped at a position where its leading end is located a predetermined amount before the transport nip portion. Since the back surface of the preceding sheet 1-A is discharged, the overlapping state is eliminated. In step S3213, the skew correcting operation of the succeeding sheet 1-B is performed by abutting the leading end of the succeeding sheet 1-B to the transport nip portion. Then, in step S3217, the succeeding sheet 1-B is searched.

  If the succeeding sheet 1-B has reached the specified position, the overlapping amount is calculated in step S3206. At this time, processing differs depending on whether or not there is an overlap reduction amount calculated in the overlap amount calculation process. In step S3207, it is determined whether or not the overlap reduction amount exists. If the overlap reduction amount does not exist, the skew correcting operation of the succeeding sheet 1-B can be performed during the last line image forming operation on the back surface of the preceding sheet 1-A. Yes, the process proceeds to step S3214. In step S3214, the process waits for the start of the image forming operation of the preceding sheet 1-A.

  In step S3215, the skew correcting operation of the succeeding sheet 1-B is performed by abutting the leading end of the succeeding sheet 1-B against the transport nip while maintaining the overlapping state. In step S3216, the process waits for the end of the image forming operation of the last line on the back surface of the preceding sheet 1-A, and in step S3217, the succeeding sheet 1-B is caught while maintaining the overlapping state.

  If there is an overlap reduction amount in step S3207, the process waits for the end of the last line image forming operation on the back surface of the preceding sheet 1-A in step S3208. When the last line image forming operation on the back surface of the preceding sheet 1-A is completed, in step S3209, the back surface of the preceding sheet 1-A is conveyed to a predetermined position by the conveying roller 5 so as to have a stacking amount described later. In step S3210, the skew correcting operation of the succeeding sheet 1-B is performed by abutting the leading end of the succeeding sheet 1-B on the transport nip portion, and the cueing of the succeeding sheet 1-B is performed in step S3217.

  In step S3218, the feeding motor 206 is switched to low-speed driving. In step S3219, a recording operation is started by discharging ink from the recording head 7 onto the surface of the succeeding sheet 1-B. Specifically, the conveyance operation of intermittently conveying the surface of the succeeding sheet 1-B by the conveyance roller 5 and the image forming operation of ejecting ink from the recording head 7 moved by the carriage 10 are repeated to repeat the subsequent sheet 1-B. A recording operation is performed on the front surface, and the process returns to step S3109 in FIG.

  Next, the process of determining the preceding sheet-induced overlapping amount Lb (A) in consideration of the unique overlapping requirement generated by performing double-sided printing on the preceding sheet 1-A will be described with reference to FIG. FIG. 34 shows an ink application area determined by the amount of superposition and print data when performing the superposition operation.

  In step S3301, the length Lp (A) of the preceding sheet 1-A in the transport direction is acquired from the recording information of the preceding sheet 1-A transmitted from the host computer 214. In step S3302, a write start position Lu (AF) of print data on the front surface of the preceding sheet 1-A and a write start position Lu (AB) of print data on the back surface of the preceding sheet 1-A are acquired. In step S3303, the print length Ld (AB) of the back surface of the preceding sheet 1-A is acquired. In step S3304, the leading length Lp (A) of the preceding sheet 1-A in the transport direction, the writing start position Lu (AB) of the back surface, and the printing length Ld (AB) of the print data of the back surface are obtained. The rear end margin of the back surface of the sheet 1-A is calculated, and is set as the maximum overlap amount Lmax (AB) depending on the back surface of the preceding sheet 1-A.

  The recording apparatus according to the present embodiment has a sheet reversing mechanism, and takes into consideration not only the recording data on the back surface of the preceding sheet 1-A, which is the recording operation immediately before performing the overlapping operation, but also the recording data on the front surface of the preceding sheet 1-A. The preceding sheet-induced overlapping amount Lb (A) is determined. Here, as shown in FIG. 34, the area of the rear end side deviating from the ink application area 100A-B on the back surface of the preceding sheet 1-A, that is, the front surface of the preceding sheet 1-A is opposite to the front end margin area. It is assumed that there are ink application areas 100A-F. In this case, even in the rear end margin area of the back surface of the preceding sheet 1-A, the preceding sheet 1-A is deformed by the ink applied by the printing operation on the front surface of the preceding sheet 1-A. When the succeeding sheet 1-B is overlaid on the preceding sheet 1-A, the succeeding sheet 1-B approaches the recording head 7 as shown in FIG. 18 described in the second embodiment. For this reason, the preceding sheet-induced overlap amount Lb (A) is determined using the recording information on the surface of the preceding sheet 1-A.

  In step S3305, the maximum overlap amount Lmax (AB) dependent on the back surface of the preceding sheet 1-A calculated in step S3304 and the write start position Lu () of the recording data on the front surface of the preceding sheet 1-A acquired in step S3302. A to F), and confirm a region where no ink is applied on both sides. As shown in FIG. 34, when the maximum overlap amount Lmax (AB) depending on the back surface of the preceding sheet 1-A is larger than the write start position Lu (AF) of the recording data on the front surface of the preceding sheet 1-A, A margin M which is a fixed value is added to the difference between Lmax (AB) and Lu (AF) to obtain a preceding sheet-induced overlap reduction amount X (A) (step S3306). Also, as shown in FIG. 35, whether the maximum overlap amount Lmax (AB) depending on the back surface of the preceding sheet 1-A is the same as the write start position Lu (AF) of the recording data on the front surface of the preceding sheet 1-A. If the value is smaller, the process advances to step S3307 to set the preceding sheet-induced overlap reduction amount X (A) to a margin M which is a fixed value.

  In step S3308, the preceding sheet-based overlapping amount Lb (A) is calculated from the preceding sheet-based overlapping reduction amount X (A) and the maximum overlapping amount Lmax (AB).

  On the other hand, there is an upper limit LM of the overlapped distance mechanically due to the transport path sandwiched by the transport guide 15 and the arrangement of the transport roller 5 and the feed roller 3. Therefore, the preceding sheet-based overlapping amount Lb (A) calculated from the recording data is compared with the upper limit LM of the overlapping distance, and if the upper limit LM is smaller, the preceding sheet-based overlapping amount Lb (A) is set to the value of LM. (Steps S3309 and S3310).

  As described above, the preceding sheet-based overlapping amount Lb (A) is calculated.

  According to the above-described embodiment, sheet contamination, paper jam, deterioration of image quality, and the like, which occur when a high-density double-sided printing is performed by superimposing a succeeding sheet on a preceding sheet, are suppressed, and the printing speed is increased. Becomes possible.

  [Embodiment 6] Next, with reference to FIGS. 36 to 39, a description will be given of a process of determining a preceding sheet-induced overlap amount Lb (A) according to Embodiment 6. FIG.

  The device configuration of this embodiment is the same as that of the first embodiment, and includes the same sheet reversing mechanism as that of the fifth embodiment.

  FIG. 36 shows a process for determining the preceding sheet-induced overlapping amount Lb (A) in consideration of a unique overlapping requirement generated by performing duplex printing on the preceding sheet 1-A. FIG. 37 shows an ink application area determined by the amount of overlap and print data when performing the overlap operation.

  In steps S3601 to S3604, the maximum overlap amount Lmax (AB) is obtained as in steps S3301 to S3304 in FIG.

  In step S3605, the preceding sheet-based overlap reduction amount X (A) is calculated. Here, the details of the process of calculating the preceding sheet-induced overlap reduction amount X (A) will be described with reference to FIG. In step S3801, for easy explanation, the rounding process is performed so that the recording area Ld (AF) on the front surface of the preceding sheet 1-A is m times (m is an integer) the distance L0 in the transport direction of the unit area. I do. In step S3802, as shown in FIG. 39, the recording area is divided into m into a (1) to a (m). At this time, the distance of the area a (m) in the transport direction may be less than L0.

  In steps S3803 to S3805, it is sequentially determined from a region on the front end side of the surface of the preceding sheet 1-A whether or not a predetermined recording density is exceeded, and detection of the recording density da (i) in the region a (i) is performed. Do. The processing for detecting the recording density da (i) is the same as that in FIG. 11, and a description thereof will be omitted.

In step S3806, it is determined whether the recording density da (i) in the area a (i) exceeds the threshold value d0. If the recording density da (i) in the area a (i) exceeds the threshold value d0, in step S3808, the area XX (A) where the succeeding sheet 1-B can be superimposed based on the recording density on the surface of the preceding sheet 1-A. Is calculated. Here, it is assumed that the recording density da (3) of the area a (3) exceeds the threshold value d0. The shaded area in FIG. 39 is the recording density at which the recording density of the area a (3) is the highest, and the recording density of this area is the value of da (3). Since the recording density da (3) has exceeded the threshold value d0, XX (A) becomes as shown in FIG.
XX (A) = L0 * (3-1)
Becomes If the recording density da (i) does not exceed the threshold value d0 in all the areas a (i), the process advances to step S3809 to change XX (A) to the print length of the recording data of the surface of the preceding sheet 1-A. Let Ld (AF).

In step S3810, the maximum overlap amount Lmax (AB) depending on the back surface of the preceding sheet 1-A and the overlappable distance (XX) from the edge of the recording sheet obtained from the recording density of the surface of the preceding sheet 1-A (A) + Lu (AF)). When the maximum overlap amount Lmax (AB) that depends on the back surface of the preceding sheet 1-A is larger, the preceding sheet-induced overlap reduction amount X (A) is obtained by adding a fixed amount of margin M to the difference between the two values. In addition,
X (A) = Lmax (AB)-(XX (A) + Lu (AF)) + M
(Step S3811). If the two values are the same or the maximum overlap amount Lmax (AB) depending on the back surface of the preceding sheet 1-A is smaller, the preceding sheet-induced overlap reduction amount X (A) is a fixed value of the margin M Is set to (step S3812).

  Returning to FIG. 36, in step S3606, the overlap reduction amount X (A) dependent on the front surface of the preceding sheet 1-A calculated in step S3605 and the maximum overlap dependent on the back surface of the preceding sheet 1-A calculated in step S3604. From the amount Lmax (A−B), the preceding sheet-induced overlapping amount Lb (A) is calculated.

  On the other hand, there is an upper limit LM of the overlapped distance mechanically due to the transport path sandwiched by the transport guide 15 and the arrangement of the transport roller 5 and the feed roller 3. Therefore, the preceding sheet-based overlapping amount Lb (A) calculated from the recording data is compared with the upper limit LM of the overlapping distance, and if the upper limit LM is smaller, the preceding sheet-based overlapping amount Lb (A) is set to the value of LM. (Steps S3607 and S3608).

  As described above, the preceding sheet-based overlapping amount Lb (A) is calculated.

  According to the above-described embodiment, sheet contamination, paper jam, deterioration of image quality, and the like, which occur when a high-density double-sided printing is performed by superimposing a succeeding sheet on a preceding sheet, are suppressed, and the printing speed is increased. Becomes possible.

  Seventh Embodiment Next, with reference to FIGS. 40 and 41, a description will be given of a process for determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B according to the seventh embodiment.

  In the present embodiment, double-sided printing is continuously performed in the same manner as in the fifth and sixth embodiments. However, double-sided printing of a plurality of recording sheets is performed after all recording sheet surface recording operations are completed. The recording operation on the back surface of the sheet is performed.

  The device configuration of this embodiment is the same as that of the first embodiment, and includes the same sheet reversing mechanism as that of the fifth embodiment.

  FIG. 40 shows a process of determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B in consideration of the unique overlapping requirement generated by performing the duplex printing on the succeeding sheet 1-B. ing. FIG. 41 shows an ink application area determined by the amount of overlap and print data when performing the overlap operation.

  In step S4001, the overlap amount Lb (A) that depends on the front and back surfaces of the preceding sheet 1-A is calculated as in FIG.

  As shown in FIG. 41, an ink application area 100 </ b> B-F is located on the front side of the back side of the subsequent sheet 1 -B corresponding to the front end margin area deviating from the ink application area 100 </ b> B-B on the back surface of the subsequent sheet 1 -B. There is. In this case, even in the rear end margin area of the back surface of the succeeding sheet 1-B, the succeeding sheet 1-B is deformed by the ink applied by the printing operation on the front surface of the succeeding sheet 1-B. When the succeeding sheet 1-B is overlaid on the preceding sheet 1-A, the succeeding sheet 1-B approaches the recording head as shown in FIG. 13 described in the first embodiment. Therefore, the overlap amount Lt (B) between the back surface of the preceding sheet 1-A and the front surface of the succeeding sheet 1-B is determined using the recording information on the front surface of the succeeding sheet 1-B.

  In step S4002, the start positions Lu (BF) and Lu (BB) of the front and back surfaces of the succeeding sheet 1-B are acquired. In step S4003, the two write-out positions are compared, and a value obtained by subtracting a fixed value of the margin M from the smaller value is the overlapping amount (the succeeding sheet-based overlapping amount) Lu (B) depending on the succeeding sheet 1-B. (Steps S4004 and S4005). Further, the preceding sheet-based overlapping amount Lb (A) calculated in step S4001 is compared with the overlapping amount Lu (B) dependent on the succeeding sheet 1-B (step S4006), and the smaller value is used as the final overlapping amount Lt. (B) (steps S4007 and S4008).

  As described above, the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B is calculated.

  According to the above-described embodiment, sheet contamination, paper jam, deterioration of image quality, and the like, which occur when a high-density double-sided printing is performed by superimposing a succeeding sheet on a preceding sheet, are suppressed, and the printing speed is increased. Becomes possible.

  [Eighth Embodiment] Next, with reference to FIGS. 42 to 47, a description will be given of a process of determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B according to the eighth embodiment.

  In the present embodiment, similarly to the sixth and seventh embodiments, the double-sided printing of a plurality of recording sheets is performed, and after the recording operation of all the recording sheet front surfaces is completed, the recording operation of all the recording sheet rear surfaces is performed.

  The device configuration of this embodiment is the same as that of the first embodiment, and includes the same sheet reversing mechanism as that of the fifth embodiment.

  FIGS. 42 to 45 determine the overlap amount Lt (B) between the preceding sheet 1-A and the succeeding sheet 1-B in consideration of the unique overlapping requirement generated by performing duplex printing on the succeeding sheet 1-B. The processing is shown. FIG. 46 shows an ink application area determined by the amount of superimposition and print data when performing the superimposition operation.

  In step S4201, the overlap amount Lb (A) depending on the front and back surfaces of the preceding sheet 1-A is calculated as in FIG. In step S4202, the succeeding sheet-based overlap reduction amount Y (B) is calculated. FIG. 43 shows details of the processing.

  In FIG. 43, in step S4301, the write start positions Lu (BF) and Lu (BB) of the front and back surfaces of the succeeding sheet 1-B are acquired. In step S4302, the two write-out positions are compared, and the smaller one is set as the recording start position reference for the succeeding sheet 1-B (steps S4303, S4304). In step S4305, the print density detection area LDA (B) is calculated by integrating the front and back of the succeeding sheet 1-B for calculating the overlap amount. In steps S4306 and S4307, the recording density of the front and back sides of the succeeding sheet 1-B is detected. Here, it is desirable that the recording density of the front surface is actually detected during the recording operation of the front surface, and the recording density is stored in a memory (not shown). Therefore, step S4306 is executed during the continuous recording operation of all the front surfaces only. It does not matter. FIGS. 44A and 44B show details of the recording density detection processing on the front and back surfaces of the succeeding sheet 1-B in steps S4306 and S4307, respectively. Only the surface recording density detection shown in FIG. In step S4401, the rounding process is performed so that the recording area Ld (BF) on the surface of the succeeding sheet 1-B is m times (m is an integer) the distance L0 in the transport direction of the unit area, for ease of explanation. It shall be. As shown in FIG. 47A, the recording area is divided into m by a (1) to a (m) (step S4402). At this time, the distance of the area a (m) in the transport direction may be less than L0. In steps S4403 to S4406, the recording density is detected sequentially from the front end region of the surface of the succeeding sheet 1-B. The process of detecting the recording density daf (i) in the area af (i) in step S4405 is the same as that in FIG. 11, and a description thereof will be omitted.

  Referring back to FIG. 43, in steps S4308 and S4309, the recording density detection area LDA (B) for the front and back sides of the succeeding sheet 1-B is divided, and areas a (1) to a (m) are set. In steps S4310 to S4312, the recording density da (i) is sequentially detected from the leading edge area a (i) during the back surface recording operation of the succeeding sheet 1-B. FIG. 45 shows details of the process in step S4312. In step S4501, the write start positions on the front and back of the succeeding sheet 1-B are compared. Here, the case where the writing start position Lu (BF) on the front surface is small as shown in FIG. 47B (NO in S4501) will be described as an example, but the writing start position Lu (BF) on the front surface is better. If it is larger (YES in S4510), it can be similarly considered by reversing the front and back (S4502, S4503). In this case, the process advances to step S4504 to extract the detection area ab (j) on the back surface opposite to the recording density detection area af (i) on the front surface of the succeeding sheet 1-B. In FIG. 47 (b), the opposing part of af (1) has a margin and ab (1), and the opposing part of af (2) has ab (1) and ab (2). ab (i-1). In step S4505, the total recording density (Duty) of the front and back sides is calculated. Since the detection area a (i) matches the detection area af (i) of the reference surface, the recording density (Duty) daf (i) of the surface is directly added. Since the detection area ab (i) on the back side does not match the detection area a (i) for the front and back sides, it is necessary to determine which area the recording density should be added. Thus, the larger of the recording densities dab (i) and dab (i-1) of the target areas ab (i) and ab (i-1) extracted in step S4504 is set as the addition target. That is, the front and back recording density da (i) of the area a (i) is the sum of daf (i) and dab (i) or dab (i-1), whichever is greater.

Returning to FIG. 43, in step S4313, it is determined whether or not the calculated front and back recording density da (i) exceeds the threshold value d0. The area up to i-1) is the overlappable area. Therefore, the succeeding sheet-induced overlap reduction amount Y (B) is calculated as follows: Y (B) = (m− (i−1)) * L0
(Step S4415).

Referring back to FIG. 42, in step S4203, the final overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B is calculated as follows: Lt (B) = Lb (A) −Y (B)
Set as

  According to the above-described embodiment, sheet contamination, paper jam, deterioration of image quality, and the like, which occur when a high-density double-sided printing is performed by superimposing a succeeding sheet on a preceding sheet, are suppressed, and the printing speed is increased. Becomes possible.

  Ninth Embodiment Finally, a ninth embodiment will be described with reference to FIG.

  In each of the above-described embodiments, the so-called serial system in which the recording unit including the recording head is guided and supported by the guide rail so as to be able to reciprocate in the main scanning direction. On the other hand, the present embodiment is a case of a so-called line head system in which the recording head is provided in the entire area in the paper width direction orthogonal to the transport direction.

  FIG. 48 is a schematic cross-sectional view showing the internal configuration of the recording apparatus according to the present embodiment. The transport path and the transport of the recording sheet 1 from the feed tray 11 to the discharge roller 9 are the same as those described in the above embodiments. It is the same as the recording device of the system. The recording head 70 is a line head provided with nozzles (not shown) for discharging ink over the entire area in the sheet width direction.

  In the line head system, the recording sheet 1 sent from the pickup roller 2 to the transport roller 5 via the feed roller 3 is transported by the transport roller 5 at a constant speed so as to pass through the facing portion of the line head 70. . The line head 70 ejects ink onto the recording sheet 1 in accordance with the transport speed of the transport roller 5 to form an image. Unlike the serial method, the line head method basically forms an image in the same image area by only one carrying operation. Therefore, the ejection frequency and the transport speed of the line head 70 are changed according to the image resolution, that is, the print quality. For example, in the high-speed printing mode, thinning printing is performed to lower the image resolution in accordance with the increase in the transport speed. In the high image quality mode, printing is performed so as to increase the image resolution according to the decrease in the transport speed.

  The process of determining the overlap amount Lt (B) of the preceding sheet 1-A and the succeeding sheet 1-B according to the present embodiment is basically the same as that in FIG. In the process of calculating the preceding sheet-induced overlap reduction amount X (A) shown in FIG. 19, the recording density Dmax is obtained from the function shown in FIG. This function has a characteristic that, as well as the environmental temperature and environmental humidity, the value decreases as the image resolution increases or the transport speed of the recording sheet decreases, and based on the function selected according to each recording condition. The preceding sheet-induced overlap reduction amount X (A) is calculated.

  Further, in the calculation processing of the succeeding sheet-induced overlap reduction amount Y (B) shown in FIG. 10, whether or not overlap is possible is determined for each of the areas a (1) to a (3) based on the recording density threshold value d0. I have. The threshold value d0 has a characteristic that, as well as the environmental temperature and the environmental humidity, the threshold value decreases as the image resolution increases or the transport speed of the recording sheet decreases, and is selected according to each recording condition. The succeeding sheet-based overlap reduction amount Y (B) is calculated based on the threshold value d0 of the recording density.

  The final overlap amount Lt (B) is calculated from the succeeding sheet-based overlap amount Y (B) obtained as described above and the preceding sheet-based overlap amount Lb (A) already calculated.

  According to the above-described embodiment, it is possible to suppress sheet stains, paper jams, deterioration in image quality, and the like, which occur when performing high-density printing in a recording apparatus that performs recording by the line head method, and achieve high-speed printing. Become.

  [Other Embodiments] The present invention is also realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program and reads the program. This is the process to be performed.

DESCRIPTION OF SYMBOLS 1 ... Recording sheet, 2 ... Pickup roller, 3 ... Feeding roller, 5 ... Conveying roller, 7 ... Recording head, 201 ... MPU, 202 ... ROM, 203 ... RAM

Claims (12)

Feeding means for feeding the sheet,
Conveying means for conveying the sheet fed by the feeding means,
Recording means for performing recording by discharging ink on a sheet conveyed by the conveying means,
A reversing path for reversing the front and back of the sheet recorded on the first surface by the recording unit and transporting the sheet to the transport unit;
Transport control means for controlling the transport of the preceding sheet and the succeeding sheet fed next to the preceding sheet, and superimposing the leading end of the succeeding sheet on the preceding sheet which has been turned upside down by the reverse path. ,
The transport control unit determines an overlapping amount of the preceding sheet and the succeeding sheet based on an amount of ink ejected to a predetermined area on at least one of the first surface and the second surface of the preceding sheet. A recording device characterized by the above-mentioned. Feeding means for feeding the sheet,
  Conveying means for conveying the sheet fed by the feeding means,
  Recording means for performing recording by discharging ink on a sheet conveyed by the conveying means,
  A reversing path for reversing the front and back of the sheet recorded on the first surface by the recording unit and transporting the sheet to the transport unit;
  Transport control means for controlling the transport of the preceding sheet and the succeeding sheet fed next to the preceding sheet, and superimposing the leading end of the succeeding sheet on the preceding sheet which has been turned upside down by the reverse path. ,
  The conveyance control means determines an overlapping amount of the preceding sheet and the succeeding sheet based on an amount of ink ejected to a predetermined area on at least one of the first surface and the second surface of the succeeding sheet. A recording device characterized by the above-mentioned. The transfer control means, based on the amount of ink ejected in a predetermined area of the first face of the subsequent sheet, according to claim 2, wherein determining said preceding sheet and overlapping of the succeeding sheet Recording device. 4. The transport control unit according to claim 1, wherein the overlapping amount when the ink amount is larger than a threshold is smaller than the overlapping amount when the ink amount is smaller than the threshold . 5. Item 2. The recording device according to item 1 . It said conveyance control means, a recording apparatus according to any one of claims 1 to 4, characterized in that overlapping the leading end of the succeeding sheet on the second surface of the preceding sheet. 6. The recording apparatus according to claim 1, wherein the conveyance control unit overlaps a leading end portion of the subsequent sheet with the preceding sheet between the feeding unit and the conveyance unit. 7. . When the sheet is conveyed to perform recording on the first surface, the sheet does not pass through the reversing path. When the sheet is reversed after recording on the first surface, the sheet passes through the reversing path. the recording apparatus according to any one of claims 1, wherein 6. The reverse path is a recording apparatus according to any one of claims 1 to 7, characterized in that it has a curved portion. Feeding means for feeding the sheet,
Conveying means for conveying the sheet fed by the feeding means,
Recording means for performing recording by discharging ink on a sheet conveyed by the conveying means,
A reversing path for reversing the front and back of the sheet on which the recording is performed on the first surface by the recording unit and transporting the sheet to the transport unit;
Controlling the conveyance of the preceding sheet and the succeeding sheet fed next to the preceding sheet, and having a control step of superposing the leading end of the succeeding sheet on the preceding sheet whose front and back are reversed by the reversing path ,
In the control step, the overlapping amount of the preceding sheet and the succeeding sheet may be determined based on an amount of ink ejected to a predetermined area on at least one of the first surface and the second surface of the preceding sheet. A method of controlling a recording device, which is characterized by Feeding means for feeding the sheet,
  Conveying means for conveying the sheet fed by the feeding means,
  Recording means for performing recording by discharging ink on a sheet conveyed by the conveying means,
  A reversing path for reversing the front and back of the sheet on which the recording has been performed on the first surface and transporting the sheet to the transporting means, comprising:
  Controlling the conveyance of the preceding sheet and the succeeding sheet fed next to the preceding sheet, and having a control step of superposing the leading end of the succeeding sheet on the preceding sheet whose front and back are reversed by the reversing path,
  In the controlling step, the overlapping amount of the preceding sheet and the succeeding sheet is determined based on an amount of ink ejected to a predetermined area on at least one of the first surface and the second surface of the succeeding sheet. A method of controlling a recording device, which is characterized by the following. A program for causing a computer to execute each step of the control method according to claim 9 . A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to claim 9 .