JP7350129B2 - Recording device and its control method, program, storage medium - Google Patents

Description

The present invention relates to sheet conveyance technology in a printing apparatus having a print head.

In recent years, it is expected that printing speeds will further increase in recording devices in order to improve productivity, and one way to increase printing speed is to narrow the interval between continuously fed recording sheets. Can be mentioned. Techniques for narrowing the gap between recording sheets include simply reducing the gap between the preceding sheet and the following sheet, as well as conveying the trailing sheet by overlapping the trailing edge of the preceding sheet with the margin area at the leading edge of the succeeding sheet, and then transferring the recording sheet as it is. There is a method of forming an image in a state where the two are overlapped (see Patent Document 1). This means that image formation is performed while minimizing wasteful areas other than the image forming area (intervals between recording sheets, margins of recording sheets), which is extremely effective in terms of speeding up printing. It is an effective method.

Japanese Patent Application Publication No. 2001-324844

However, especially in inkjet recording apparatuses, when high-density printing using a large amount of ink is performed in areas where recording sheets overlap, wavy wrinkles called cockling occur on the recording sheets due to moisture in the ink. For example, when a part of the leading edge of the succeeding sheet overlaps the margin area of the trailing edge of the preceding sheet, the back side of the sheet is restrained by a flat plate. Therefore, due to the cockling, the recording sheet may be lifted up and rubbed against the recording head, resulting in dirt on the recording sheet, or the recording sheet may not be conveyed to a discharge roller or the like, resulting in a paper jam. Furthermore, if the distance between the print head and the surface of the print sheet becomes unstable, there is a possibility that the image quality will deteriorate due to a shift in the landing position of the ink.

The present invention has been made in view of the above problems, and its purpose is to suppress the inconveniences that occur when carrying out high-density printing by stacking and conveying a succeeding sheet on top of a preceding sheet, and to realize a technology that can speed up printing. It is.

In order to solve the above problems, a recording apparatus of the present invention includes a feeding roller that feeds a sheet, a conveying roller that conveys the sheet fed by the feeding roller in the conveying direction, and a recording apparatus that conveys the sheet by the conveying roller. a recording means for recording by discharging ink onto a sheet conveyed in a direction; and a recording means for reversing the front and back of the sheet recorded on the first side by the recording means and guiding the sheet to the feeding roller. and a control means for controlling the conveyance of a preceding sheet and a subsequent sheet that is fed next to the preceding sheet, and the control means is configured to control the conveyance of the preceding sheet that has been turned upside down by the guiding section. Two sides are recorded by the recording means, and a stacked state is formed in which the leading edge of the succeeding sheet is overlapped with the second face of the preceding sheet.

According to the present invention, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density printing by stacking and conveying a succeeding sheet on top of a preceding sheet, and it is possible to speed up printing. .

FIG. 4 is a diagram illustrating the operation of continuous overlapping feeding in the recording apparatus of the present embodiment. FIG. 4 is a diagram illustrating the operation of continuous overlapping feeding in the recording apparatus of the present embodiment. FIG. 4 is a diagram illustrating the operation of continuous overlapping feeding in the recording apparatus of the present embodiment. FIG. 3 is a diagram illustrating the configuration of a pickup roller according to the present embodiment. FIG. 2 is a functional block diagram of the recording apparatus of this embodiment. 2 is a flowchart illustrating the operation of continuous overlapping feeding according to the present embodiment. FIG. 3 is a diagram illustrating an operation of stacking a succeeding sheet on a preceding sheet according to the present embodiment. FIG. 3 is a diagram illustrating an operation of stacking a succeeding sheet on a preceding sheet according to the present embodiment. 7 is a flowchart showing a process for determining the overlap amount Lt(B) according to the first embodiment. 7 is a flowchart illustrating a process for determining an overlapping reduction amount Y(B) due to subsequent sheets according to the first embodiment. 7 is a flowchart showing processing for detecting recording density according to the first embodiment. FIG. 3 is a schematic diagram showing an overlapping area of recording sheets according to the first embodiment. FIG. 3 is a schematic diagram showing how the succeeding sheet stacked on the preceding sheet is cocked in Embodiment 1; FIG. 3 is an explanatory diagram of recording density detection area division according to the first embodiment. FIG. 7 is a diagram showing a threshold table for determining the overlapping reduction amount Y(B) due to subsequent sheets in the first embodiment. 10 is a flowchart showing a process for determining an overlapping amount Lb(A) due to the preceding sheet according to the second embodiment. FIG. 7 is a schematic diagram showing a state of a cock ring near the rear end of the preceding seat in Embodiment 2; FIG. 7 is a schematic diagram showing how paper floats in a subsequent sheet stacked on a cockled preceding sheet in Embodiment 2; 10 is a flowchart showing a process for determining an overlapping reduction amount X(A) due to preceding sheets according to the second embodiment. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets in Embodiment 2. FIG. FIG. 7 is a schematic diagram showing a recording density detection area and a unit area in Embodiment 2. FIG. FIG. 7 is a diagram showing a function for determining the overlapping reduction amount X(A) due to the preceding sheet in Embodiment 2; FIG. 7 is a diagram showing a table for determining a function for calculating the overlap reduction amount X(A) due to the preceding sheet in the second embodiment. 12 is a flowchart showing a process for determining the overlap amount Lt(B) according to the third embodiment. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets in Embodiment 3. FIG. 7 is a diagram showing a table that is changed for each recording condition in order to determine a function for calculating the amount of overlap reduction due to the preceding sheet X(A) in the third embodiment. FIG. 7 is a diagram showing a table that is changed for each printing condition in order to determine a threshold value for determining the overlap reduction amount Y(B) due to subsequent sheets in the third embodiment. 10 is a flowchart illustrating a process for determining the overlap reduction amount Y(B) due to subsequent sheets according to the fourth embodiment. FIG. 7 is a diagram illustrating the operation of continuous overlapping feeding in double-sided printing according to the fifth embodiment. FIG. 7 is a diagram illustrating the operation of continuous overlapping feeding in double-sided printing according to the fifth embodiment. 12 is a flowchart illustrating a continuous overlapping feeding operation in double-sided printing according to the fifth embodiment. 12 is a flowchart illustrating a continuous overlapping feeding operation in double-sided printing according to the fifth embodiment. 12 is a flowchart showing a process for determining an overlapping amount Lb(A) due to the preceding sheet according to the fifth embodiment. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets according to Embodiment 5. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets according to Embodiment 5. 12 is a flowchart showing a process for determining an overlapping amount Lb(A) due to the preceding sheet according to the sixth embodiment. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets according to a sixth embodiment. 12 is a flowchart showing a process for determining an overlapping reduction amount X(A) due to preceding sheets according to a sixth embodiment. FIG. 7 is an explanatory diagram of recording density detection area division according to the sixth embodiment. 12 is a flowchart showing a process for determining the overlap amount Lt(B) according to the seventh embodiment. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets according to Embodiment 7. 12 is a flowchart showing a process for determining the overlap amount Lt(B) according to the eighth embodiment. 12 is a flowchart showing a process for determining the overlap amount Lt(B) according to the eighth embodiment. 10 is a flowchart illustrating a process for determining an overlapping reduction amount Y(B) due to subsequent sheets according to Embodiment 8. 10 is a flowchart illustrating a process for determining an overlapping reduction amount Y(B) due to subsequent sheets according to Embodiment 8. FIG. 7 is a schematic diagram showing an overlapping area of recording sheets according to Embodiment 8. FIG. 7 is an explanatory diagram of recording density detection area division according to the eighth embodiment. FIG. 9 is a side sectional view schematically showing the device configuration of Embodiment 9.

Hereinafter, one 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 the main structure and continuous overlapping feeding operation of a recording apparatus according to an embodiment of the present invention. First, with reference to FIG. 1, a schematic configuration of the recording apparatus of this embodiment will be described.

In ST1 of FIG. 1, 1 is a recording sheet. A plurality of recording sheets 1 are stacked on a feed tray 11 (loading section). Reference numeral 2 denotes a pickup roller that comes into contact with the uppermost recording sheet 1 stacked on the feed tray 11 and picks up this recording sheet. A feeding roller 3 feeds the recording sheet 1 picked up by the pickup roller 2 to the downstream side in the sheet conveyance direction. Reference numeral 4 denotes a feeding driven roller which is biased toward the feeding roller 3 and which, together with the feeding roller 3, nip and feed the recording sheet 1.

A conveying roller 5 conveys 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 that is biased toward the conveying roller 5 and, together with the conveying roller 5, pinches and conveys the recording sheet.

A recording head 7 performs recording on the recording sheet 1 conveyed by the conveyance roller 5 and the pinch roller 6. This embodiment will be described as an inkjet recording head that performs recording on a recording sheet 1 by ejecting ink from the recording head. A platen 8 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 conveyance direction.

Reference numeral 9 denotes a discharge roller for discharging the recording sheet printed by the recording head 7 out 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 is performed by the recording head 7. Here, the spur 13 on the downstream side is biased toward the discharge roller 9, and the spur 12 on the upstream side does not have the discharge roller 9 disposed at a position facing it. The spur 12 is for preventing the recording sheet 1 from lifting up, and is also called a presser 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 moved 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 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 presser lever for overlapping the leading edge of the succeeding sheet with the trailing edge of the preceding sheet. The sheet presser lever 17 has the state ST1 in FIG. 1 as a neutral point, and the first lever part 17A is biased by a spring in the counterclockwise direction in the figure around the rotating shaft 17b, so that the tip of the first lever part 17A The second lever portion 17B, that is, the tip portion 17c of the second lever portion 17B that contacts the recording sheet 1 is biased by a spring clockwise in the figure around the rotating shaft 17a. Reference numeral 22 denotes a sheet detection sensor for detecting the leading edge and trailing edge of the recording sheet 1. The sheet detection sensor 22 detects the timing at which the leading end of the recording sheet 1 enters the transport nip formed by the transport roller 5 and the pinch roller 6, and the timing at which the trailing end of the recording sheet 1 exits during the recording operation. . Reference numeral 21 denotes a reversing guide member constituting a reversing mechanism for reversing the front and back sides of the recording sheet 1. The reversing guide member 21 guides the recording sheet 1 reversely fed 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 shown in FIG. 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 feed motor, which will be described later, to the pickup roller 2. When picking up a recording sheet, the drive shaft 19 and pickup roller 2 rotate in the direction of arrow A in the figure. The drive shaft 19 is provided with a protrusion 19a. The pickup roller 2 is formed with a recess 2c into which the protrusion 19a fits. As shown in FIG. 4(a), when the protrusion 19a is in contact with the first surface 2a of the recess 2c of the pickup roller 2, the drive of the drive shaft 19 is transmitted to the pickup roller 2, and the drive shaft 19 is When driven, the pickup roller 2 is also rotated. On the other hand, as shown in FIG. 4(b), when the protrusion 19a is in contact with the second surface 2b of the recess 2c of the pickup roller 2, the drive of the drive shaft 19 is not transmitted to the pickup roller 2, and the drive Even if the shaft 19 is driven, the pickup roller 2 is not rotated. Even when the protrusion 19a does not come into 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 does not occur even if the drive shaft 19 is driven. Roller 2 is not rotated.

FIG. 5 is a block diagram of the recording apparatus of this embodiment. Reference numeral 201 denotes an MPU that controls operations of various parts, data processing, and the like. As will be described later, the MPU 201 also functions as a conveyance control unit that can control the conveyance of the recording sheet so that the trailing edge of the preceding recording sheet and the leading edge of the succeeding sheet overlap. 202 is a ROM that 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 print head 7 is controlled by a print head driver 207. A carriage motor 204 that drives the carriage 10 is controlled by a carriage motor driver 208. The conveyance roller 5 and the discharge roller 9 are driven by a conveyance motor 205. The transport motor 205 is controlled by a transport motor driver 209. The pickup roller 2 and the feed roller 3 are driven by a feed motor 206. Feed motor 206 is controlled by feed motor driver 210.

The host computer 214 is provided with a printer driver 2141 that collects print information such as a print image and print image quality and communicates with the printing apparatus when a user instructs execution of a print operation. The MPU 201 exchanges recorded images and the like with the host computer 214 via the I/F unit 213.

Referring to ST1 in FIG. 1 to ST9 in FIG. 3, the operation of overlapping continuous feeding in continuous printing on only one side (front side) will be described in chronological order. When recording data is transmitted from the host computer 214 via the I/F unit 213, it is processed by the MPU 201 and then expanded into the RAM 203. 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. As a result, 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, the configuration may be such that only the feeding roller that feeds the recording sheets stacked on the stacking section is provided.

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

In ST2, by continuing to rotate the feed roller 3, the leading end of the preceding sheet 1-A pushes up the flapper 20 against its own weight, and further pushes the sheet presser lever 17 against the rotation axis against the biasing force of the spring. 17b in a clockwise direction. When the feed roller 3 continues to rotate further, the leading edge of the preceding sheet 1-A hits the conveyance nip formed by the conveyance roller 5 and the pinch roller 6. At this time, the conveyance 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 hits the transport nip, the leading edge of the leading sheet 1-A hits the transport nip and is aligned, correcting the skew. be done. The skew correction operation is also called a registering operation.

In ST3, when the skew correction operation of the preceding sheet 1-A is completed, the conveyance motor 205 is driven and the conveyance roller 5 starts rotating. The conveyance roller 5 conveys the sheet at a rate of 15 inches/sec. After the preceding sheet 1-A is indexed to a position facing the recording head 7, a recording operation is performed by ejecting ink from the recording head 7 based on the recording data. Note that in the cueing operation, the leading edge of the recording sheet is brought into contact with the conveyance nip, thereby once being positioned at the position of the conveyance roller 5, and then the amount of rotation of the conveyance roller 5 is controlled based on the position of the conveyance roller 5. This is done by

The recording apparatus of this embodiment is a serial type recording apparatus in which a recording head 7 is mounted on a carriage 10, and a conveyance operation in which a recording sheet is intermittently conveyed by a predetermined amount by a conveyance roller 5, and a conveyance operation when the conveyance roller 5 is stopped. The recording operation on the recording sheet is performed by repeating the image forming operation of discharging ink from the recording head 7 while moving the carriage 10 on which the recording head 7 is mounted.

When the preceding sheet 1-A is cued up, the feeding motor 206 is switched to low speed drive. That is, the pickup roller 2 and the feeding roller 3 rotate at 7.6 inches/sec. When the recording sheet is intermittently conveyed by a predetermined amount by the conveyance roller 5, the feed roller 3 is also intermittently driven by the feed motor 206. That is, when the conveying roller 5 is rotating, the feeding roller 3 is also rotating, and when the conveying roller 5 is stopped, the feeding roller 3 is also stopped. The rotation speed of the feed roller 3 is smaller than the rotation speed of the conveyance roller 5. Therefore, the sheet is stretched between the conveying roller 5 and the feeding roller 3. Further, the feeding roller 3 is caused to rotate along with the recording sheet conveyed by the conveying roller 5.

In order to drive the feed motor 206 intermittently, the drive shaft 19 is also driven. As mentioned above, the rotational speed of the pickup roller 2 is smaller than the rotational speed of the conveyance roller 5. Therefore, the pickup roller 2 is rotated together with the recording sheet conveyed by the conveyance roller 5. That is, the pickup roller 2 is in a state in which it moves ahead of the drive shaft 19. Specifically, the protrusion 19a of the drive shaft 19 is spaced apart from the first surface 2a and in contact with the second surface 2b. Therefore, even if the trailing edge of the preceding sheet 1-A passes the pickup roller 2, the second recording sheet (following sheet 1-B) is not picked up immediately. When the drive shaft 19 is driven for a predetermined period of 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 picks up the succeeding sheet 1-B. The sheet detection sensor 16 requires a predetermined distance or more between sheets in order to detect the edge of the recording sheet due to factors such as sensor responsiveness. That is, in order to provide a predetermined time interval after the sheet detection sensor 16 detects the trailing edge of the preceding sheet 1-A and until the leading edge of the trailing sheet 1-B is detected, the trailing edge of the trailing sheet 1-A is It is necessary to keep a predetermined distance away from the leading edge of the succeeding sheet 1-B. For this purpose, the angular range θ of the recessed portion 2c of the pickup roller 2 is set to approximately 70 degrees.

In ST5, the subsequent sheet 1-B picked up by the pickup roller 2 is conveyed by the feeding roller 3. 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. 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 drive. That is, the pickup roller 2 and the feeding roller 3 rotate at 20 inches/sec.

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

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 leading sheet 1-A, the leading edge of the trailing sheet 1-B is positioned at a predetermined position upstream of the conveyance nip. It is conveyed by the feed roller 3 until it stops. The position of the leading edge of the succeeding sheet 1-B is calculated from the amount of rotation of the feeding roller 3 after the leading edge 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 conveying roller 5 is stopped to perform the image forming operation (ink ejecting operation) for the last line of the preceding sheet 1-A, the feeding roller 3 is driven to perform the image forming operation (ink ejecting operation) of the succeeding sheet 1-B. The leading end is brought into contact with the conveyance nip portion to correct the skew of the succeeding sheet 1-B.

In ST9, when the image forming operation for the last row of the preceding sheet 1-A is completed, the conveying roller 5 is rotated by a predetermined amount to maintain the state in which the succeeding sheet 1-B is overlapped with the preceding sheet 1-A. It is possible to cue the succeeding sheet 1-B. A recording operation is performed on the subsequent sheet 1-B by the recording head 7 based on the recording data. When the succeeding sheet 1-B is intermittently conveyed for the recording operation, the preceding sheet 1-A is also intermittently conveyed, and eventually the preceding sheet 1-A is discharged out of the recording apparatus by the discharge roller 9.

When the succeeding sheet 1-B is located, the feeding motor 206 is switched to low speed drive. That is, the pickup roller 2 and the feeding roller 3 rotate at 7.6 inches/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 section 213, a 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 low speed. The pickup roller 2 rotates at 7.6 inches/sec. The pickup roller 2 picks up the preceding sheet 1-A, and the feeding roller 3 feeds the preceding sheet 1-A toward the recording head 7.

In step S3, wait until the leading edge 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, in step S4, the feeding motor 206 is switched to high-speed drive. That is, the pickup roller 2 and the feeding roller 3 rotate at 20 inches/sec. Further, by controlling the amount of rotation of the feeding 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 moved to the conveyance nip portion in step S5. Abutment is performed to correct the skew of the preceding sheet 1-A.

In step S6, the preceding sheet 1-A is cued based on the recorded data. That is, by controlling the amount of rotation of the conveyance roller 5, the preceding sheet 1-A is conveyed to the recording start position based on the position of the conveyance roller 5 based on the recording data. In step S7, the feeding motor 206 is switched to low speed drive. In step S8, the recording operation is started by ejecting ink from the recording head 7 onto the preceding sheet 1-A. Specifically, by repeating a conveyance operation in which the preceding sheet 1-A is intermittently conveyed by the conveyance roller 5, and an image forming operation (ink discharge operation) in which the carriage 10 is moved and ink is discharged from the recording head 7, A recording operation is performed on the preceding sheet 1-A. In synchronization with the operation of intermittently conveying the preceding sheet 1-A by the conveyance roller 5, the feed motor 206 is intermittently driven at a low speed. That is, the pickup roller 2 and the feeding roller 3 rotate intermittently at 7.6 inches/sec.

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

On the other hand, if it is determined in step S9 that there is recording data for the next page, the feeding operation of the subsequent sheet 1-B is started in step S10. Specifically, the pickup roller 2 picks up the subsequent sheet 1-B, and the feeding roller 3 feeds the subsequent sheet 1-B toward the recording head 7. 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 large relative to 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. shipped in condition.

In step S11, the sheet detection sensor 16 waits for the leading edge of the succeeding sheet 1-B to be detected. When the sheet detecting sensor 16 detects the leading edge of the succeeding sheet 1-B, in step S12, the feeding motor 206 Switch to high-speed drive. That is, the pickup roller 2 and the feeding roller 3 rotate at 20 inches/sec. By controlling the amount of rotation of the feeding roller 3 after the leading edge of the succeeding sheet 1-B is detected by the sheet detection sensor 16, in step S13, the leading edge of the trailing sheet 1-B is positioned within the transport nip by a predetermined amount. The subsequent sheet 1-B is conveyed so that it is in the front position. The preceding sheet 1-A is intermittently conveyed based on recording data. By continuously driving the feeding motor 206 at high speed, the succeeding sheet 1-B is stacked such that the leading edge of the trailing sheet 1-B overlaps the trailing edge of the preceding sheet 1-A.

In step S14, it is determined whether the leading edge of the succeeding sheet 1-B has reached a specified position (P3 of ST5 in FIG. 8, which will be described later). cue up. Specifically, when the image forming operation for the last row of the preceding sheet 1-A is completed in step S29, the ejecting operation of the preceding sheet 1-A is performed in step S30. During this time, since the feeding motor 206 is not driven, the leading end of the succeeding sheet 1-B remains at a position a predetermined amount before the conveyance nip. Since the preceding sheet 1-A is ejected, the overlapping state is resolved. In step S31, the leading end of the succeeding sheet 1-B is brought into contact with the conveyance nip portion to correct the skew of the succeeding sheet 1-B, and in step S35, the leading edge of the succeeding sheet 1-B is positioned.

On the other hand, if the subsequent sheet 1-B has reached the specified position in step S14, the overlapping amount is calculated in step S15. Thereafter, the processing differs depending on whether or not there is an overlap reduction amount calculated in the overlap amount calculation process. In step S16, it is determined whether or not there is an overlap reduction amount, and if there is no overlap reduction amount, it is possible to perform the skew correction operation for the succeeding sheet 1-B during the image forming operation for the last row of the preceding sheet 1-A. Therefore, the process advances to step S32. In step S32, the process waits for the image forming operation on the preceding sheet 1-A to start. In step S33, the leading end of the succeeding sheet 1-B is brought into contact with the conveyance nip portion while maintaining the stacked state, and the skew correction operation of the succeeding sheet 1-B is performed. In step S34, it is determined whether the image forming operation for the last row of the preceding sheet 1-A has been completed. If it has been completed, in step S35, the succeeding sheet 1-B is cued 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 row image forming operation of the preceding sheet 1-A in step S17. When the last row image forming operation of the preceding sheet 1-A is completed, the process proceeds to step S18, and the preceding sheet 1-A is conveyed to a predetermined position by the conveying roller 5 so that the overlapping amount, which will be described later, is achieved. In step S19, the leading end of the succeeding sheet 1-B is brought into contact with the conveyance nip portion to correct the skew of the succeeding sheet 1-B, and then, in step S35, the succeeding sheet 1-B is indexed.

In step S36, the feeding motor 206 is switched to low speed drive. In step S37, the recording operation is started by ejecting ink from the recording head 7 onto the succeeding sheet 1-B. Specifically, by repeating a conveyance operation in which the subsequent sheet 1-B is intermittently conveyed by the conveyance roller 5, and an image forming operation (ink discharge operation) in which the carriage 10 is moved and ink is discharged from the recording head 7, A recording operation is performed on the subsequent sheet 1-B. In synchronization with the operation of intermittently conveying the succeeding sheet 1-B by the conveyance roller 5, the feed motor 206 is intermittently driven at a low speed. That is, the pickup roller 2 and the feeding roller 3 rotate intermittently at 7.6 inches/sec.

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

FIGS. 7 and 8 are diagrams illustrating the operation of stacking a succeeding sheet on a preceding sheet in this embodiment. The operation described in steps S12 and S13 of FIG. 6 to form the overlapping state in which the leading edge of the succeeding sheet is overlapped with the trailing edge of the preceding sheet will be described.

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 of conveying the recording sheet by the conveying roller 5 and the feeding roller 3 will be described in order 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 stacked on the preceding sheet will be described with reference to ST3 and ST4 in FIG. A third state in which it is determined whether or not to perform the skew correction operation for the subsequent sheet while maintaining the overlapping state will be described with reference to ST5 in FIG. 8.

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 edge of the succeeding sheet 1-B. The distance from the sheet detection sensor 16 to the position P1 where the subsequent sheet 1-B can be stacked 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 configuration of the mechanism.

In the first state, there is a case where the chasing motion is stopped in the first section A1. If the leading edge of the succeeding sheet 1-B passes the rear end of the preceding sheet 1-A before P1, as in ST2 in FIG. 7, the operation of stacking the succeeding sheet on the preceding sheet is not performed.

In FIG. 8, in ST3, a second section A2 is defined from the aforementioned P1 to the position P2 where the sheet presser lever 17 is provided. In the second section A2, the subsequent sheet 1-B is stacked on the preceding sheet 1-A.

In the second state, there is a case where the operation of stacking the succeeding sheet on the preceding sheet is stopped in the second section A2. As in ST4 of FIG. 8, if the leading edge of the succeeding sheet 1-B cannot catch up with the trailing edge of the preceding sheet 1-A within the second section A2, the operation of stacking the preceding sheet on the succeeding sheet cannot be performed.

In ST5, the period from P2 to P3 described above is defined as a third section A3. P3 is the position of the leading edge when the succeeding sheet is stopped in step S13 in FIG. The succeeding sheet 1-B is overlapped with the preceding sheet 1-A and is conveyed until the leading edge of the succeeding sheet 1-B reaches P3. In the third section A3, it is determined whether or not to perform cueing by abutting the succeeding sheet 1-B against the conveyance nip while maintaining the overlapping state. That is, it is determined whether to maintain the overlapping state and perform the skew correction operation to cue up, or to cancel the overlapping state and perform the skew correction operation to cue up.

Next, with reference to FIGS. 9 to 15, a process for determining the overlapping amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B will be described.

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

The paper size of the preceding sheet 1-A is acquired from the recorded 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 conveyance direction is acquired (step S901). . Furthermore, the writing start position Lu(A) and data length Ld(A) of the data to be recorded on the preceding sheet 1-A are obtained from the recording information (steps S902, S903). As shown in FIG. 12, the trailing edge margin Lmax(A) of the preceding sheet 1-A is determined from the length Lp(A) of the preceding sheet 1-A, the writing start position Lu(A), and the recording data length Ld(A). It can be calculated. The overlapping amount depending on the preceding sheet 1-A (the overlapping amount due to the preceding sheet The amount of overlap) is set to Lb(A) (step S904). Here, from the viewpoint of simplifying the explanation, it is assumed that the recording data length Ld(A) is acquired at the start of recording of the preceding sheet 1-A. The length Ld(A) may also be obtained.

On the other hand, due to the conveyance path sandwiched by the conveyance guide 15 and the arrangement of the conveyance roller 5 and the feed roller 3, there is a mechanically upper limit LM of the overlapping distance. Therefore, the overlapping amount Lb(A) due to the preceding sheet 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 overlapping amount Lb(A) due to the preceding sheet is set to the value of LM. (steps S905, S906).

Next, calculation processing of the overlap reduction amount Y(B) depending on the subsequent sheet 1-B (overlap reduction amount due to the subsequent sheet) is performed.

In step S907, the writing position Lu(B) of the 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-induced reduction amount Y(B) is calculated. When performing a recording operation (overlap printing) by overlapping the succeeding sheet 1-B on the preceding sheet 1-A, as shown in FIG. There is a preceding sheet 1-A between them. Since the back surface of the succeeding sheet 1-B is restrained not by the platen rib 8a but by the preceding sheet 1-A, when the recording density at the leading edge of the succeeding sheet is high, the succeeding sheet 1-B is restrained by the deformed height due to cockling. B approaches the recording head 7. Therefore, if the deformation height due to cockling is large and there is a possibility that the succeeding sheet 1-B and the recording head 7 will rub, it is necessary to set the overlap reduction amount Y(B) due to the succeeding sheet to avoid overprinting. .

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

In step S1001, the recording density detection area LDA( Find B).

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

The recording density da(i) is determined by the number of ink ejected dots in a unit area within a predetermined recording density detection area. The amount of ink ejected varies depending on the nozzle diameter, but the large color (cyan, magenta, yellow) dot is defined as the reference (=1), the small color dot is defined as the reference x 1/8, and the black is defined as the reference x 2. In this embodiment, 600 dpi is defined as one pixel, and the recording density when the amount of ink per pixel is reference x 2 is defined as 100%. As shown in FIG. 14, in this embodiment, the distance of the unit area in the transport direction (sub-scanning direction) 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 amount of ink per block of 1 pixel x 1 pixel in this unit area.

FIG. 11 shows details of the recording density detection process in step S1004 in FIG. First, the maximum value Dmax of recording density is set as an initial value (S1101), and in the recording density detection area a(1), recording densities D in detected unit areas are sequentially acquired (Step S1102). Next, it is compared with the maximum value Dmax of the recording density D that has already been obtained (step S1103), and the maximum value Dmax is updated (step S1104). Then, the processes from step S1102 to step S1104 are 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, recording densities da(2) and da(3) are detected in areas a(2) and a(3), respectively.

Further, a threshold value of a predetermined recording density is set as d0, and the threshold value d0 is compared with the recording densities da(1) to da(3). FIG. 15 shows the recording density threshold d0, and is set so that the threshold d0 decreases 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, the comparison starts from the region a(1) on the tip side, and if the threshold value d0 is exceeded, overlapping is not possible from that region. First, in order to determine whether or not the area a(1) can be overlapped, the recording density da(1) is compared with a threshold value d0 (step S1005). When the recording density da(1) exceeds the threshold value d0, the area a(1) cannot be overlapped, and the overlap reduction amount due to subsequent sheets Y(B) is calculated as follows: Y(B)=m・L0=3× L0
is set (step S1006), and this processing ends.

On the other hand, if the recording density da(1) is equal to or lower than the threshold value d0 in step S1005, the area a(1) is allowed to be overlapped, and the process moves to the process for determining whether or not the area a(2) is allowed to be overlapped. In step S1007, it is determined whether or not overlapping is possible for area a(2) in the same way as for area a(1), and if overlapping is not possible, the overlapping reduction amount Y(B) due to the subsequent sheet is calculated (step S1008), and the process is ended. . If overlapping is possible, the process moves to determining whether overlapping is possible for area a(3). In step S1009, it is similarly determined whether the area a(3) can be overlapped, and if it is not possible to overlap, the overlap reduction amount Y(B) due to the subsequent sheet is calculated (step S1010), and the process ends. If overlapping is possible, since all of the determination areas are overlapping possible, the overlapping reduction amount Y(B) due to the subsequent sheet is set to zero (step S1011), and the process ends.

The final overlap amount Lt(B) is calculated from the overlap reduction amount Y(B) due to the succeeding sheet obtained as described above and the overlap amount Lb(A) due to the preceding sheet which has already been calculated (FIG. 9 step S909).

In addition, in the process of calculating the overlapping amount Lt(B) in FIG. 9, the reduction amount Y(B) due to the subsequent sheet is calculated based on the recording density da(1) to da(3), as explained in FIGS. 10 and 11. However, the amount of deformation of the subsequent sheet 1-B is estimated based on each recording density da(1) to da(3) and other recording conditions (number of printing passes or time required for recording). Y(B) may also be determined based on the amount of deformation.

In addition, in the process of calculating the overlapping amount Lt(B) described above, the recording density threshold was changed according to the number of printing passes in image formation, but if the number of printing passes is large, the image quality priority mode is set. The overlapping operation may not be performed.

In addition, if the overlap reduction amount Y(B) due to the subsequent sheet is zero, the trailing edge margin amount excluding the predetermined overlap margin X(0) of the preceding sheet 1-A will be overlapped, but always by a constant amount. The present invention does not include cases where the trailing end margin amount is overlapped taking into account the overlapping margin of .

Furthermore, in this embodiment, the area where no printing is performed at the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is defined as a margin. shall be included in the invention.

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density printing by conveying a succeeding sheet in a stacked manner on a preceding sheet, and it is possible to speed up printing. becomes.

[Embodiment 2] Next, with reference to FIGS. 16 to 23, a process for determining the overlapping amount Lb(A) due to the preceding sheet according to Embodiment 2 will be described.

Note that the device configuration of this embodiment is the same as that of Embodiment 1, so a description thereof will be omitted.

FIG. 16 shows the process of calculating the overlapping amount Lb(A) due to the preceding sheet according to the present embodiment.

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

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

In step S1605, the amount of overlap reduction depending on the preceding sheet 1-A (the amount of overlap reduction due to the preceding sheet) X(A) is calculated. When the recording density at the trailing edge of the preceding sheet 1-A is high, deformation due to cockling occurs in the vicinity of the trailing edge including the margin area as shown in FIG. 17, and as shown in FIG. It may float a little. In this case, when the succeeding sheet 1-B is stacked on the preceding sheet 1-A, the succeeding sheet 1-B approaches the recording head 7 compared to the posture 1-B-a of the succeeding sheet 1-B when the preceding sheet 1-A is not stacked. It turns out. It is necessary to set the overlap reduction amount X(A) due to the preceding sheet 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 process of calculating the overlapping reduction amount X(A) due to the preceding sheet in step S1605 of FIG. 16.

As shown in FIG. 20, the overlapping reduction amount X(A) due to the preceding sheet is set according to the recording density of the preceding sheet 1-A, and is calculated from the final position of the recorded 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 of 1-B. The overlap reduction amount Y(B ) may be added. In this embodiment, the necessary overlapping reduction amount X(A) due to the preceding sheet is determined according to the recording density D of a predetermined recording density detection area.

The recording density D is determined by the number of ink ejected dots in a unit area within a predetermined recording density detection area. As shown in FIG. 21, in this embodiment, the distance in the transport direction of a unit area is L0, the distance in the main scanning direction is W0, and 600 dpi is one pixel, so that L0 is 256 pixels and W0 is 640 pixels. Further, the recording density detection area is an area within 1028 pixels from the trailing edge of the preceding sheet in the conveyance direction. Within this recording density detection area, the recording density D is calculated from the average amount of ink per block of 1 pixel x 1 pixel.

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

The overlapping reduction amount X(A) due to the preceding sheet is determined 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 values shown in FIG. 23 according to the number of printing passes in image formation. Note that a lower limit value X0 is set for the overlapping reduction amount X(A) due to the preceding sheet based on the overlapping accuracy of the feeding roller 3 and the conveying roller 5.

The overlap amount Lb(A) due to the preceding sheet is calculated from the overlap reduction amount X(A) due to the preceding sheet and the maximum overlap amount Lmax(A) determined as described above (step S1606).

On the other hand, due to the conveyance path sandwiched by the conveyance guide 15 and the arrangement of the conveyance roller 5 and the feed roller 3, there is a mechanically upper limit LM of the overlapping distance. Therefore, the overlapping amount Lb(A) due to the preceding sheet 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 overlapping amount Lb(A) due to the preceding sheet is set to the value of LM. (steps S1607, S1608).

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

According to this embodiment, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density printing by conveying a succeeding sheet on top of a preceding sheet, and it is possible to speed up printing. Become.

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

This embodiment differs from the first and second embodiments described above in that it determines the final overlap amount Lt(B) by taking into account differences in environmental conditions such as temperature and humidity. ), the calculation method of the overlapping reduction amount Y(B) due to the subsequent sheet is different.

The device configuration of this embodiment is the same as that of Embodiment 1 except that a temperature sensor and a humidity sensor (not shown) are provided.

FIG. 24 shows the process of calculating the overlap amount Lt(B) according to this embodiment.

Similarly to FIGS. 9 and 16, the length Lp(A) of the preceding sheet 1-A, the writing start position Lu(A) of the recorded data, and the data The length Ld(A) is obtained (steps S2401 to S2403). The trailing edge margin of the preceding sheet 1-A is calculated from the obtained length Lp (A) of the preceding sheet 1-A, the writing start position Lu (A), and the data length Ld (A), and the maximum overlap amount Lmax (A) is calculated. (Step S2404).

Next, the overlap reduction amount X(A) due to the preceding sheet is calculated (step S2405). The details of the process for calculating the overlapping reduction amount X(A) due to the preceding sheet are almost the same as in FIG. 19 . In other words, the overlapping reduction amount X(A) due to the preceding sheet is set according to the recording density of the preceding sheet 1-A, and is calculated from the final 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 tip position (see FIG. 25). The final margin distance provided from the final position of the recorded data of the preceding sheet 1-A to the leading edge position of the next succeeding sheet 1-B is calculated by adding the overlapping reduction amount Y(B) due to the subsequent sheet, which will be described later. Ru. In this embodiment, the necessary overlap reduction amount X(A) due to the preceding sheet is determined according to the print density of a predetermined print density detection area.

As described with reference to FIG. 19, the processes of steps S1902 to S1905 are repeated for each recording density detection area to obtain the final recording density Dmax. The overlapping reduction amount X(A) due to the preceding sheet is determined based on the recording density Dmax from the function F1 shown in FIG. 22 (step S1906). FIG. 26 shows a table for determining parameters t1, t2, h1, h2, p1, and p2 used when calculating variables D1 and D2 shown in FIG. 22. In FIG. 26, each parameter is set for each of the environmental temperature and humidity of the recording device, and the number of printing passes for one-pass printing or multiple multi-pass printing in image formation, and based on these recording conditions. Select each applicable parameter. D01 and D02 are the values of variables D1 and D2 under the standard recording conditions, and the variables D1 and D2 under each recording condition are calculated from the following formula based on these standard values.

D1=t1*h1*p1*D01
D2=t2*h2*p2*D02
In other words, the function for determining the overlap reduction amount X(A) due to the preceding sheet can be changed depending on the recording conditions such as environmental temperature, environmental humidity, and number of printing passes. Note that a lower limit value X0 is set for the overlapping reduction amount X(A) due to the preceding sheet based on the overlapping accuracy of the feeding roller 3 and the conveying roller 5.

The overlap amount Lb(A) due to the preceding sheet is calculated from the overlap reduction amount X(A) due to the preceding sheet and the maximum overlap amount Lmax(A) determined as described above (step S2406).

On the other hand, due to the conveyance path sandwiched by the conveyance guide 15 and the arrangement of the conveyance roller 5 and the feed roller 3, there is a mechanically upper limit LM of the overlapping distance. Therefore, the overlapping amount Lb(A) due to the preceding sheet 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 overlapping amount Lb(A) due to the preceding sheet is set to the value of LM. (steps S2407, S2408).

Next, calculation processing of the overlap reduction amount Y(B) due to the subsequent sheet is performed.

In step S2409, the writing position Lu(B) of the 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 S2410, the overlap reduction amount Y(B) due to the subsequent sheet is calculated. The details of the process for calculating the overlapping reduction amount Y(B) due to the subsequent sheet are almost the same as in FIG. 10 . That is, in steps S1001 to S1004 described with reference to FIG. 10, the recording densities da(1) to da(3) of the recording density detection areas a(1) to a(3) are detected.

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

d0=t3*h3*p3*d00
Next, the final overlap amount Lt(B ) is calculated (step S2411).

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration in image quality, etc. that occur when performing high-density printing by conveying the succeeding sheet 1-B in a stacked manner on the preceding sheet 1-A. It becomes possible to speed up printing.

[Embodiment 4] Next, with reference to FIG. 28, a method for calculating the overlap reduction amount Y(B) due to subsequent sheets in Embodiment 4 will be described.

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

The apparatus configuration of this embodiment, the process of determining the final overlap amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B, and the process of calculating the overlap reduction amount X(A) due to the preceding sheet are as follows: , is the same as Embodiment 1, so the explanation will be omitted.

FIG. 28 shows the process of calculating the overlap reduction amount Y(B) due to the subsequent sheet 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 subsequent sheet 1-B is determined, and the recording density detection area LDA(B) is Rounding up is performed so that the distance L0 is multiplied by m (m is an integer) (step S1002). Here, for convenience of explanation, m=4, and the recording density detection area is divided into four regions a(1), a(2), a(3), and a(4) (step S2803). Then, for 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 defined as the recording density da(1) to da(4). (Step S2804).

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

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

Comparison is performed starting from the region a(1) on the tip side, and if the threshold value DA0 is exceeded, overlapping is not possible from that region. First, in order to determine whether or not the area a(1) can be overlapped, the overlapability determination value DA(1) is compared with the threshold value DA0 (step S2806). If the stackability determination value DA(1) exceeds the threshold value DA0, the area a(1) cannot be stacked, and the stacking reduction amount due to the subsequent sheet Y(B) is calculated as follows: Y(B)=m・L0= 4 x L0
is set (step S2807), and the overlapping reduction amount Y(B) calculation process due to the subsequent sheet is ended.

On the other hand, if the overlapping possibility determination value DA(1) is less than or equal to the threshold value DA0, the area a(1) becomes overlapping possible, and the process moves to the overlapping ability determination for the area a(2). Thereafter, similarly to area a(1), it is determined whether overlapping is possible starting from area a(2), and if overlapping is not possible, the overlapping reduction amount Y(B) due to the subsequent sheet is calculated (S2807), and if overlapping is possible, The process moves to determining whether or not the next area can be overlapped (step S2808). By repeating these processes for area a(2) and beyond, the final overlapping reduction amount Y(B) due to subsequent sheets is calculated (steps S2808 to S2814).

The final overlapping amount Lt(B) is calculated from the overlapping reduction amount Y(B) due to the subsequent sheet obtained as described above and the overlapping amount Lb(A) due to the preceding sheet which has already been calculated.

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density printing by conveying a succeeding sheet in a stacked manner on a preceding sheet, and it is possible to speed up printing. becomes.

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

Since the device configuration of this embodiment is the same as that of Embodiment 1, description thereof will be omitted.

Referring to ST11 in FIG. 29 to ST16 in FIG. 30, the reversing operation of the recording sheet in the double-sided printing mode will be described in chronological order. Note that the single-sided printing operation 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 recording operation of the preceding sheet 1-A is completed, the rotation of the conveyance roller 5 and the discharge roller 9 is stopped. Rotate the conveyance roller 5 and discharge roller 9 until the rear end of the preceding sheet 1-A is at a distance LA from the conveyance nip between the conveyance roller 5 and the pinch roller 6, and remove the preceding sheet 1-A that has passed through the conveyance nip. It is held by a discharge roller 9 and a spur 13. At this time, the flapper 20 is in a downward position as shown in the figure due to its own weight, and guides the preceding sheet 1-A to the reversing guide member 21.

In ST12, the conveyance roller 5 and the discharge roller 9 rotate in the opposite direction to the recording operation (clockwise in the figure), and re-enter the preceding sheet 1-A into the conveyance nip between the conveyance roller 5 and the pinch roller 6. , the sheet is transported in the direction of the transport guide 15 and the sheet presser lever 17. At this time, the conveyance roller 5 rotates at 8 inches/sec.

In ST13, as the conveyance roller 5 continues to rotate clockwise in the figure, the end of the preceding sheet 1-A (the rear end when printing the front side) resists the biasing force of the spring and presses the tip 17c of the sheet presser lever 17. It is rotated counterclockwise around the rotating shaft 17a. Here, the sheet presser lever 17 may be configured such that the end of the preceding sheet 1-A passes below the tip 17c of the sheet presser lever 17 without contacting it. Further, as the conveying 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 conveyance roller 5 continues to rotate, the end of the preceding sheet 1-A (the trailing edge when printing the front side) is guided by the reversing guide member 21, and the feed roller 3 and the feed driven roller It enters the feeding nip section of No.4. Further, when the sheet detection sensor 16 detects the edge of the preceding sheet 1-A (the trailing edge when printing the front side), the rotation of the conveyance roller 5 and the feeding roller 3 is stopped once after the conveyance roller 5 has rotated by a predetermined amount. do. At this time, the conveyance path is configured by the conveyance guide 15 and the reversing guide member 21 so that the other end of the preceding sheet 1-A (the leading edge at the time of surface printing) reliably passes through the conveyance nip. Further, when the end of the preceding sheet 1-A (the rear end when printing the front side) reaches the tip 17c of the sheet presser lever 17, the other end of the preceding sheet 1-A (the leading edge when printing the front side) reaches the sheet presser lever 17. 17 so as to pass through the tip 17c.

In ST15, by continuing to rotate the feeding roller 3, the edge of the preceding sheet 1-A (the trailing edge when printing the front side) pushes up the flapper 20 against its own weight and the reaction force of the preceding sheet 1-A. It joins the conveyance guide 15 again. At this time, since the other end of the preceding sheet 1-A (the leading edge when printing the front side) is not in contact with the sheet presser lever 17, the end of the preceding sheet 1-A (the trailing edge when printing the front side) presses the flapper 20. The reaction force of the preceding sheet 1-A when pushing up can be minimized. When the feed roller 3 continues to rotate further, the end of the preceding sheet 1-A hits the conveyance nip formed by the conveyance roller 5 and the pinch roller 6, and slants, similar to ST2 in FIG. Perform line correction.

In ST16, when the skew correction operation of the preceding sheet 1-A is completed, the conveyance motor 205 is driven and the conveyance roller 5 starts rotating. The conveyance roller 5 conveys the sheet at a rate of 15 inches/sec. The preceding sheet 1-A is indexed to a position facing the recording head 7, but 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 side. A recording operation is performed by discharging ink from the recording head 7 based on the recording data on the back side of the preceding sheet 1-A for which the cueing has been completed.

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

Thereafter, the continuous overlapping operation of the back side of the preceding sheet 1-A and the succeeding sheet 1-B up to ST9 in FIG. 3 is the same as in the first embodiment.

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

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

In step S3103, the sheet detection sensor 16 detects the leading edge of the preceding sheet 1-A. 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 drive in step S3104. That is, the pickup roller 2 and the feeding roller 3 rotate at 20 inches/sec. By controlling the amount of rotation of the feeding 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 conveyance nip portion in step S3105, and the leading edge of the preceding sheet 1-A is moved forward. Perform the skew correction operation for the sheet 1-A.

In step S3106, the preceding sheet 1-A is cued based on the recorded data. That is, by controlling the amount of rotation of the conveyance roller 5, the preceding sheet 1-A is conveyed to the recording start position based on the position of the conveyance roller 5 based on the recording data. In step S3107, the feeding motor 206 is switched to low speed drive. In step S3108, the printing operation is started by ejecting ink from the printing head 7 onto the surface of the preceding sheet 1-A. Specifically, by repeating a conveyance operation in which the preceding sheet 1-A is intermittently conveyed by the conveyance roller 5, and an image forming operation (ink discharge operation) in which ink is discharged from the recording head 7 moved by the carriage 10, A recording operation is performed on the surface of the preceding sheet 1-A.
In synchronization with the operation of intermittently conveying the preceding sheet 1-A by the conveyance roller 5, the feed motor 206 is intermittently driven at a low speed. That is, the pickup roller 2 and the feeding roller 3 rotate intermittently at 7.6 inches/sec.

In step S3109, completion of the recording operation on the front surface of the preceding sheet 1-A is waited for, and the process proceeds to step S3110, in which the rear end of the preceding sheet 1-A is conveyed to a predetermined position (LA in ST11 in FIG. 29). In step S3111, it is confirmed whether the recording sheet has a sheet length that can be reversed. The sheet length of the preceding sheet 1-A is confirmed, and if it is outside the predetermined range, the process advances to step S3112, where the preceding sheet 1-A is ejected, and the process ends. The sheet length of the preceding sheet 1-A is confirmed, and if it is within a predetermined range, the process advances to step S3114 and waits for drying for a predetermined time.

In step S3115, reverse rotation of the conveyance roller 5 and discharge roller 9 and forward rotation of the feeding roller 3 are started, and the preceding sheet 1-A is reversed. When the preceding sheet 1-A passes the sheet detection sensor 16 in step S3116, the rotation of the transport roller 5, discharge roller 9, and feed roller 3 is stopped in step S3117. In step S3118, drying is waited for a predetermined time, and in step S3119, the feeding roller 3 is rotated to feed the preceding sheet 1-A toward the recording head 7 again.

In step S3120, the process waits for the leading edge of the preceding sheet 1-A to be detected by the sheet detection sensor 22. 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 conveyance nip portion, and the leading edge of the preceding sheet 1-A is tilted. A line correction operation is performed (step S3121).

In step S3122, the preceding sheet 1-A is cued based on the recorded data. In step S3123, the recording operation is started by ejecting ink from the recording head 7 onto the back surface of the preceding sheet 1-A.

In step S3124, it is determined whether there is record data for the next page. If there is no record data for the next page, wait for the completion of the recording operation for the preceding sheet 1-A in step S3126, and when the recording operation is completed for the preceding sheet 1-A, in step S3127. 1-A is ejected, and the recording operation ends in step S3128.

Note that if it is determined in step S3124 that there is recording data for the next page, the process advances to step S3125 and a double-sided overlapping operation is started.

FIG. 32 shows the double-sided stacking operation sequence in step S3125 of FIG. 31.

If there is recording data for the next page in step S3124, the feeding operation of the succeeding sheet 1-B is started in step S3201. Specifically, the pickup roller 2 picks up the subsequent sheet 1-B, and the feeding roller 3 feeds the subsequent sheet 1-B toward the recording head 7. 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 large relative to the protrusion 19a of the drive shaft 19, the succeeding sheet 1-B has a predetermined distance from the rear end of the back surface of the preceding sheet 1-A. It will be delivered in the same condition.

In step S3202, the sheet detection sensor 16 detects the leading edge of the succeeding sheet 1-B. 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 drive in step S3203. That is, the pickup roller 2 and the feeding roller 3 rotate at 20 inches/sec. By controlling the amount of rotation of the feeding 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 trailing sheet 1-B is positioned a predetermined amount before the conveyance nip. The subsequent sheet 1-B is conveyed so as to be at the position. The back side of the preceding sheet 1-A is intermittently conveyed based on the recording data. By continuously driving the feeding motor 206 at high speed, the succeeding sheet 1-B is stacked such that the leading edge of the front surface 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 been reached here, the overlapping state is canceled and the succeeding sheet 1-B is cued up. Specifically, when the image forming operation for the last row on the back side of the preceding sheet 1-A is completed in step S3211, the ejecting operation for the back side of the preceding sheet 1-A is performed in step S3212. During this time, since the feed motor 206 is not driven, the leading edge of the surface of the succeeding sheet 1-B remains at a position a predetermined amount before the conveyance nip. Since the back side of the preceding sheet 1-A is discharged, the overlapping state is eliminated. In step S3213, the leading edge of the succeeding sheet 1-B is brought into contact with the conveyance nip portion to correct the skew of the succeeding sheet 1-B. Then, in step S3217, the next sheet 1-B is cued up.

If the subsequent sheet 1-B has reached the specified position, the overlapping amount is calculated in step S3206. At this time, the 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 there is an overlap reduction amount, and if there is no overlap reduction amount, it is possible to perform the skew correction operation for the succeeding sheet 1-B during the last row image forming operation on the back side of the preceding sheet 1-A. Yes, the process advances to step S3214. In step S3214, the process waits for the image forming operation on the preceding sheet 1-A to start.

In step S3215, the leading edge of the succeeding sheet 1-B is brought into contact with the conveyance nip portion while maintaining the stacked state, and the skew correction operation of the succeeding sheet 1-B is performed. Then, in step S3216, the end of the image forming operation on the last row on the back side of the preceding sheet 1-A is waited for, and in step S3217, the succeeding sheet 1-B is cued while maintaining the overlapping state.

If there is an overlap reduction amount in step S3207, the process waits for the end of the last row image forming operation on the back side of the preceding sheet 1-A in step S3208. When the last row image forming operation on the back side of the preceding sheet 1-A is completed, in step S3209, the back side of the preceding sheet 1-A is conveyed to a predetermined position by the conveying roller 5 so that the overlapping amount, which will be described later, is achieved. In step S3210, the leading edge of the succeeding sheet 1-B is brought into contact with the conveyance nip portion to correct the skew of the succeeding sheet 1-B, and in step S3217, the leading edge of the succeeding sheet 1-B is positioned.

In step S3218, the feeding motor 206 is switched to low speed drive. In step S3219, the recording operation is started by ejecting ink from the recording head 7 onto the surface of the subsequent sheet 1-B. Specifically, by repeating a conveyance operation in which the surface of the subsequent sheet 1-B is intermittently conveyed by the conveyance roller 5, and an image forming operation in which ink is ejected from the recording head 7 moved by the carriage 10, the subsequent sheet 1-B is A recording operation is performed on the surface, and the process returns to step S3109 in FIG.

Next, a process for determining the amount of overlap Lb(A) due to the preceding sheet will be described with reference to FIG. 33, taking into account the unique overlap requirements that occur when double-sided printing is performed on the preceding sheet 1-A. Further, FIG. 34 shows the ink application area determined from the overlapping amount and print data when performing the overlapping operation.

In step S3301, the length Lp(A) of the preceding sheet 1-A in the transport direction is obtained from the recording information of the preceding sheet 1-A transmitted from the host computer 214. In step S3302, the writing start position Lu (AF) of the recording data on the front side of the preceding sheet 1-A and the writing start position Lu (AB) of the recording data on the back side of the preceding sheet 1-A are acquired. In step S3303, the printing length Ld(AB) of the back side of the preceding sheet 1-A is obtained. In step S3304, the preceding sheet is determined from the length Lp (A) in the conveying direction of the acquired preceding sheet 1-A, the writing start position Lu (AB) on the back side, and the printing length Ld (AB) of the recording data on the back side. The trailing edge margin of the back side of the sheet 1-A is calculated and set as the maximum overlap amount Lmax (AB) that depends on the back side of the preceding sheet 1-A.

The recording apparatus of this embodiment has a sheet reversing mechanism, and takes into consideration not only the recorded data on the back side of the preceding sheet 1-A, which is the recording operation immediately before the overlapping operation, but also the recorded data on the front side of the preceding sheet 1-A. The overlapping amount Lb(A) due to the preceding sheet is determined. Here, as shown in FIG. 34, the area on the trailing edge side away from the ink application area 100A-B on the back side of the preceding sheet 1-A, that is, the front side opposite to the trailing edge margin area, is It is assumed that there are ink application areas 100A-F. In this case, the preceding sheet 1-A is deformed by the ink applied during the recording operation on the front surface of the preceding sheet 1-A, even in the trailing edge margin area on the back surface of the preceding sheet 1-A. When the succeeding sheet 1-B is stacked 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. Therefore, the overlapping amount Lb(A) due to the preceding sheet is determined using the recorded information on the surface of the preceding sheet 1-A.

In step S3305, the maximum overlap amount Lmax (A-B) depending on the back side of the preceding sheet 1-A calculated in step S3304 and the writing start position Lu( Compare A-F) and check for areas where no ink has been applied on both the front and back sides. As shown in FIG. 34, when the maximum overlap amount Lmax (A-B) that depends on the back side of the preceding sheet 1-A is larger than the recording data start position Lu (A-F) on the front side of the preceding sheet 1-A, The fixed value margin M is added to the difference between Lmax(AB) and Lu(AF), and the overlap reduction amount due to the preceding sheet is determined as X(A) (step S3306). Also, as shown in FIG. 35, is the maximum overlapping amount Lmax (A-B) depending on the back side of the preceding sheet 1-A the same as the recording data start position Lu (A-F) on the front side of the preceding sheet 1-A? If it is smaller, the process advances to step S3307, and the overlapping reduction amount X(A) due to the preceding sheet is set to the margin M, which is a fixed value.

In step S3308, the overlap amount Lb(A) due to the preceding sheet is calculated from the overlap reduction amount X(A) due to the preceding sheet and the maximum overlap amount Lmax(AB).

On the other hand, due to the conveyance path sandwiched by the conveyance guide 15 and the arrangement of the conveyance roller 5 and the feed roller 3, there is a mechanically upper limit LM of the overlapping distance. Therefore, the overlapping amount Lb(A) due to the preceding sheet 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 overlapping amount Lb(A) due to the preceding sheet is set to the value of LM. (steps S3309, S3310).

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

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density double-sided printing by stacking and conveying a succeeding sheet on top of a preceding sheet, thereby speeding up printing. becomes possible.

[Embodiment 6] Next, with reference to FIGS. 36 to 39, processing for determining the overlapping amount Lb(A) due to the preceding sheet according to Embodiment 6 will be described.

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

FIG. 36 shows a process of determining the amount of overlap Lb(A) due to the preceding sheet, taking into account the unique overlap requirements that occur when double-sided printing is performed on the preceding sheet 1-A. Further, FIG. 37 shows the ink application area determined from the overlapping amount and recording data when performing the overlapping operation.

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

In step S3605, the overlap reduction amount X(A) due to the preceding sheet is calculated. Here, with reference to FIG. 38, details of the process of calculating the overlap reduction amount X(A) due to the preceding sheet will be described. In step S3801, for ease of explanation, rounding up is performed so that the recording area Ld (A-F) on the surface of the preceding sheet 1-A is m times the distance L0 in the transport direction of the unit area (m is an integer). do. In step S3802, as shown in FIG. 39, the recording area is divided into m sections a(1) to a(m). At this time, there is a possibility that the distance in the transport direction of area a(m) is less than L0.

In steps S3803 to S3805, it is determined whether the recording density exceeds a predetermined recording density sequentially from the area on the leading edge side of the front surface of the preceding sheet 1-A, and the recording density da(i) in area a(i) is detected. conduct. This recording density da(i) detection process is the same as that in FIG. 11, so the explanation will be omitted.

In step S3806, it is determined whether the recording density da(i) in 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 subsequent sheet 1-B can be overlapped is determined from the recording density on the surface of the preceding sheet 1-A. Calculate. Here, it is assumed that the recording density da(3) of area a(3) exceeds the threshold value d0. In the shaded area in FIG. 39, the recording density of area a(3) is the highest, and the recording density of this area has a value of da(3). Since the recording density da(3) exceeds 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 areas a(i), the process advances to step S3809, and XX(A) is set to the print length of the recording data on the front surface of the preceding sheet 1-A. Let Ld(AF) be.

In step S3810, the maximum overlapping amount Lmax (A-B) that depends on the back surface of the preceding sheet 1-A and the possible overlapping distance (XX (A)+Lu(AF)). When the maximum overlap amount Lmax (A-B) that depends on the back side of the preceding sheet 1-A is larger, the overlap reduction amount due to the preceding sheet X (A) is calculated by adding a fixed value 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 (A-B) that depends on the back side of the preceding sheet 1-A is smaller, the overlap reduction amount due to the preceding sheet X (A) is the fixed value margin M (step S3812).

Returning to FIG. 36, in step S3606, the amount of overlap reduction X(A) that depends on the front side of the preceding sheet 1-A calculated in step S3605 and the maximum overlap that depends on the back side of the preceding sheet 1-A calculated in step S3604 are determined. The overlapping amount Lb(A) due to the preceding sheet is calculated from the amount Lmax(AB).

On the other hand, due to the conveyance path sandwiched by the conveyance guide 15 and the arrangement of the conveyance roller 5 and the feed roller 3, there is a mechanically upper limit LM of the overlapping distance. Therefore, the overlapping amount Lb(A) due to the preceding sheet 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 overlapping amount Lb(A) due to the preceding sheet is set to the value of LM. (steps S3607, S3608).

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

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density double-sided printing by stacking and conveying a succeeding sheet on top of a preceding sheet, thereby speeding up printing. becomes possible.

[Embodiment 7] Next, with reference to FIGS. 40 and 41, a process for determining the overlapping amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B according to the embodiment 7 will be described.

In this embodiment, the double-sided printing is carried out in a continuous overlapping operation similar to the fifth and sixth embodiments, but the double-sided printing of multiple recording sheets is performed after the recording operations on the surfaces of all the recording sheets are completed. Performs recording operation on the back side of the sheet.

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

FIG. 40 shows a process for determining the amount of overlap Lt(B) between the preceding sheet 1-A and the succeeding sheet 1-B, taking into account the unique overlapping requirements that occur when double-sided printing is performed on the succeeding sheet 1-B. ing. Further, FIG. 41 shows the ink application area determined from the overlapping amount and recording data when performing the overlapping operation.

In step S4001, similarly to FIG. 33, an overlapping amount Lb(A) that depends on the front and back surfaces of the preceding sheet 1-A is calculated.

As shown in FIG. 41, an ink application area 100B-F is formed on the surface of the subsequent sheet 1-B corresponding to the leading end side area away from the ink application area 100B-B on the back surface of the succeeding sheet 1-B, that is, the leading edge margin area. Assume that there is. In this case, the succeeding sheet 1-B is deformed by the ink applied during the recording operation on the front surface of the succeeding sheet 1-B even in the trailing edge margin area on the back surface of the succeeding sheet 1-B. When the succeeding sheet 1-B is stacked 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 overlapping 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 recorded information on the front surface of the succeeding sheet 1-B.

In step S4002, the writing start positions Lu(BF) and Lu(BB) on the front and back sides of the subsequent sheet 1-B are acquired. In step S4003, the two writing start positions are compared, and the value obtained by subtracting the fixed value margin M from the smaller value is calculated as the overlapping amount depending on the subsequent sheet 1-B (overlapping amount due to the subsequent sheet) Lu(B). (Steps S4004, S4005). Furthermore, the overlapping amount Lb(A) due to the preceding sheet calculated in step S4001 is compared with the overlapping amount Lu(B) depending on the succeeding sheet 1-B (step S4006), and the smaller value is set as the final overlapping amount Lt. (B) (steps S4007, S4008).

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

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density double-sided printing by stacking and conveying a succeeding sheet on top of a preceding sheet, thereby speeding up printing. becomes possible.

[Eighth Embodiment] Next, with reference to FIGS. 42 to 47, processing for determining the overlapping amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B according to the eighth embodiment will be described.

In this embodiment, similarly to Embodiments 6 and 7, double-sided printing of a plurality of recording sheets is performed, and after the recording operation on the front side of all the recording sheets is completed, the recording operation on the back side of all the recording sheets 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 the fifth embodiment.

FIGS. 42 to 45 show how to determine the amount of overlap Lt(B) between the preceding sheet 1-A and the succeeding sheet 1-B, taking into account the unique overlapping requirements that occur when double-sided printing is performed on the succeeding sheet 1-B. Processing is shown. Further, FIG. 46 shows the ink application area determined from the overlapping amount and print data when performing the overlapping operation.

In step S4201, similarly to FIG. 33, an overlapping amount Lb(A) that depends on the front and back surfaces of the preceding sheet 1-A is calculated. In step S4202, the overlap reduction amount Y(B) due to the subsequent sheet is calculated. FIG. 43 shows details of the process.

In FIG. 43, in step S4301, the writing start positions Lu(BF) and Lu(BB) on the front and back sides of the succeeding sheet 1-B are acquired. In step S4302, the two writing start positions are compared, and the smaller one is set as the recording start position reference for the subsequent sheet 1-B (steps S4303, S4304). In step S4305, the recording density detection area LDA(B) is calculated by combining the front and back sides of the subsequent sheet 1-B for calculating the overlapping amount. In steps S4306 and S4307, recording density detection is performed on the front and back sides of the subsequent sheet 1-B, respectively. Here, it is preferable to detect the recording density on the front surface during the recording operation on the front surface and store the recording density in a memory (not shown), so step S4306 is executed during the continuous recording operation on all the front surfaces only. I don't mind if you do. 44(a) and 44(b) show the details of the recording density detection processing for the front and back sides of the subsequent sheet 1-B in steps S4306 and S4307, respectively. Only the recording density detection on the surface shown in (a) will be explained. In step S4401, for ease of explanation, rounding up is performed so that the recording area Ld (B-F) on the surface of the subsequent sheet 1-B is m times (m is an integer) the distance L0 in the transport direction of the unit area. It shall be. As shown in FIG. 47(a), the recording area is divided into m sections a(1) to a(m) (step S4402). At this time, there is a possibility that the distance in the transport direction of the area a(m) is less than L0. In steps S4403 to S4406, recording density is sequentially detected from the region on the leading edge side of the surface of the subsequent 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, so the explanation will be omitted.

Returning to FIG. 43, in steps S4308 and S4309, the recording density detection area LDA(B) of the front and back sides of the subsequent 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 side area a(i) during the back side recording operation of the subsequent sheet 1-B. FIG. 45 shows details of the process in step S4312. In step S4501, the writing start positions on the front and back sides of the succeeding sheet 1-B are compared. Here, we will explain the case where the writing start position Lu (BF) on the front side is small (NO in S4501) as shown in FIG. 47(b), but the writing start position Lu (BF) on the front side is If it is larger (YES in S4510), the same idea can be obtained by reversing the front and back sides (S4502, S4503). In this case, the process advances to step S4504, and a detection area ab(j) on the back side opposite to the recording density detection area af(i) on the front side of the subsequent sheet 1-B is extracted. In FIG. 47(b), the opposing part of af(1) has a margin and ab(1), the opposing part of af(2) has ab(1) and ab(2), and ab(i) and It can be expressed as ab(i-1). In step S4505, the total recording density (Duty) for both front and back sides is calculated. Since the detection area a(i) and the reference detection area af(i) on the front surface match, the recording density (duty) daf(i) on the front surface is directly added. Since the detection area ab(i) on the back side does not match the detection area a(i) on the front and back sides, it is necessary to determine which area's recording density is to be added. Therefore, the recording densities dab(i) and dab(i-1) of the target areas ab(i) and ab(i-1) extracted in step S4504 are compared, and the larger value is set as the addition target. That is, the front and back recording density da(i) of area a(i) is the sum of daf(i) and the larger of dab(i) or dab(i-1).

Returning to FIG. 43, in step S4313, it is determined whether the calculated front and back recording densities da(i) exceed a threshold value d0. If so, the area becomes a non-overlapping area, and the area a( The area up to i-1) can be overlapped. Therefore, the amount of overlap reduction due to subsequent sheets Y(B) is calculated as follows: Y(B)=(m-(i-1))*L0
(Step S4415).

Returning to FIG. 42, in step S4203, the final overlapping amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B is calculated as Lt(B)=Lb(A)-Y(B).
and set.

According to the embodiment described above, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density double-sided printing by stacking and conveying a succeeding sheet on top of a preceding sheet, thereby speeding up printing. becomes possible.

[Embodiment 9] Finally, Embodiment 9 will be described with reference to FIG. 48.

In each of the above-described embodiments, a so-called serial system was used in which the recording section including the recording head was guided and supported by a guide rail so as to be movable back and forth in the main scanning direction. On the other hand, this embodiment is a case of a so-called line head system in which the recording head is provided throughout the paper width direction perpendicular to the conveyance direction.

FIG. 48 is a schematic cross-sectional view showing the internal configuration of the recording apparatus of this embodiment, and the conveyance path for the recording sheet 1 from the feed tray 11 to the ejection roller 9 and the configuration related to conveyance are the serial number shown in each of 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) that eject ink throughout the sheet width direction.

In the line head method, the recording sheet 1 is sent from the pickup roller 2 to the conveyance roller 5 via the feed roller 3, and is conveyed by the conveyance roller 5 at a constant speed so as to pass through the opposite part of the line head 70. . The line head 70 discharges ink onto the recording sheet 1 in accordance with the transport speed of the transport roller 5 to form an image. In the line head method, unlike the serial method, an image is basically formed in the same image area by only one conveyance operation. Therefore, the ejection frequency and conveyance speed of the line head 70 are changed depending on the image resolution, that is, the print quality. For example, in high-speed printing mode, thinning printing is performed in which the image resolution is lowered as the transport speed increases. In the high image quality mode, printing is performed to increase the image resolution as the transport speed decreases.

The process of determining the overlapping amount Lt(B) of the preceding sheet 1-A and the succeeding sheet 1-B according to this embodiment is basically the same as that shown in FIG. 24. In the calculation process of the overlapping reduction amount X(A) due to the preceding sheet shown in FIG. 19, it is calculated based on the recording density Dmax from the function shown in FIG. This function has the characteristic that its value decreases not only depending on the environmental temperature and humidity, but also as the image resolution increases or the transport speed of the recording sheet decreases. The overlap reduction amount X(A) due to the preceding sheet is calculated.

Furthermore, in the process of calculating the overlapping reduction amount Y(B) due to subsequent sheets shown in FIG. There is. This threshold value d0 has a characteristic that it decreases not only depending on the environmental temperature and humidity, but also as the image resolution increases or the conveyance speed of the recording sheet decreases, and is selected according to each recording condition. The overlapping reduction amount Y(B) due to the subsequent sheet is calculated based on the recorded recording density threshold value d0.

The final overlapping amount Lt(B) is calculated from the overlapping reduction amount Y(B) due to the subsequent sheet obtained as described above and the overlapping amount Lb(A) due to the preceding sheet which has already been calculated.

According to the above-described embodiment, it is possible to suppress sheet stains, paper jams, deterioration of image quality, etc. that occur when performing high-density printing in a recording device that performs recording using a line head method, and to increase printing speed. Become.

[Other Embodiments] The present invention can also be realized by executing the following processing. That is, the software (program) that realizes the functions of the embodiments described above is supplied to a system or device via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or device reads the program. This is the process to be executed.

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

Claims (30)

a feeding roller that feeds the sheet;
a conveyance roller that conveys the sheet fed by the feed roller in the conveyance direction;
a recording unit that performs recording by discharging ink onto a sheet conveyed in the conveyance direction by the conveyance roller;
a guide section for reversing the front and back of the sheet recorded on the first side by the recording means and guiding the sheet to the feeding roller;
A control means for controlling the conveyance of a preceding sheet and a subsequent sheet fed next to the preceding sheet,
The control means causes the recording means to record on a second surface of the preceding sheet which has been reversed by the guide section, and forms an overlapping state in which a leading edge of the succeeding sheet is overlapped with the second surface of the preceding sheet. A recording device characterized by: 2. The recording apparatus according to claim 1, wherein the preceding sheet, which has been recorded on the first surface and has passed through the guide section, is abutted against the conveyance roller and corrected for skew. 3. The recording apparatus according to claim 1, wherein the subsequent sheet is corrected by being brought into contact with the conveying roller while maintaining the overlapping state. 4. The recording apparatus according to claim 1, wherein the recording means performs recording on an overlapping area where the preceding sheet and the succeeding sheet overlap. 5. If the leading edge of the succeeding sheet does not reach a predetermined position, the recording means records on the succeeding sheet after the overlapping state is resolved. recording device. a feeding roller that feeds the sheet;
a conveyance roller that conveys the sheet fed by the feed roller in the conveyance direction;
a recording unit that performs recording by discharging ink onto a sheet conveyed in the conveyance direction by the conveyance roller;
a guide section for reversing the front and back of the sheet recorded on the first side by the recording means and guiding the sheet to the feeding roller;
A control means for controlling the conveyance of a preceding sheet and a subsequent sheet fed next to the preceding sheet,
The control means forms an overlapping state in which a leading edge of the subsequent sheet is overlapped with a second surface of the preceding sheet when the preceding sheet, which has been turned upside down by the guide section, is being conveyed by the conveying roller; A recording apparatus characterized in that when the leading edge of the succeeding sheet does not reach a predetermined position, recording is performed on the succeeding sheet after the overlapping state is resolved. 7. The preceding sheet on which recording has been performed on the first side is conveyed by the conveyance roller in the opposite direction to the conveyance direction and enters the guide section. recording device. The control means may form the overlapping state by continuously driving the feeding roller while the conveying roller is being driven intermittently to convey the preceding sheet. The recording device according to any one of items 1 to 7 . A sensor for detecting the sheet is provided between the feeding roller and the conveying roller,
9. The recording apparatus according to claim 8 , wherein the control means continuously drives the feeding roller after the leading edge of the subsequent sheet is detected by the sensor. 10. The recording apparatus according to claim 1, further comprising a lever provided between the feeding roller and the conveying roller to press down the sheet fed by the feeding roller. . 11. The flapper according to claim 1, further comprising a flapper provided between the feeding roller and the conveying roller, the flapper being rotatable by the sheet fed by the feeding roller. recording device. 2. The control means determines the overlapping amount of the preceding sheet and the subsequent sheet based on recorded data of at least one of the first side and the second side of the preceding sheet. 12. The recording device according to any one of 11 . The control means may 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 succeeding sheet. The recording device according to any one of claims 1 to 12 . If the length of the preceding sheet is outside a predetermined range, the control means discharges the preceding sheet without reversing the front and back of the preceding sheet after recording the first side of the preceding sheet. The recording device according to any one of items 1 to 13. A feeding roller that feeds a sheet, a conveying roller that conveys the sheet fed by the feeding roller in the conveying direction, and recording by discharging ink onto the sheet conveyed in the conveying direction by the conveying roller. A method for controlling a recording apparatus, comprising: a recording unit; and a guide unit for reversing the front and back of a sheet recorded on a first side by the recording unit and guiding the sheet to the feeding roller. ,
a control step for controlling the conveyance of a preceding sheet and a subsequent sheet fed after the preceding sheet;
In the control step, the recording means records on the second side of the preceding sheet which has been turned upside down by the guide section, and a stacked state is formed in which the leading edge of the succeeding sheet is overlapped with the second side of the preceding sheet. A control method characterized by: 16. The control method according to claim 15 , wherein the preceding sheet, which has been recorded on the first side and has passed through the guide section, is abutted against the conveyance roller and corrected for skew. 17. The control method according to claim 15 , wherein the succeeding sheet is corrected by being brought into contact with the conveying roller while maintaining the stacked state. 18. The control method according to claim 15 , wherein the recording means performs recording on an overlapping area where the preceding sheet and the succeeding sheet overlap. 19. If the leading edge of the succeeding sheet does not reach a predetermined position , the recording means records on the succeeding sheet after the overlapping state is resolved. control method. A feeding roller that feeds a sheet, a conveying roller that conveys the sheet fed by the feeding roller in the conveying direction, and recording by discharging ink onto the sheet conveyed in the conveying direction by the conveying roller. A method for controlling a recording apparatus, comprising: a recording unit; and a guide unit for reversing the front and back of a sheet recorded on a first side by the recording unit and guiding the sheet to the feeding roller. ,
a control step for controlling the conveyance of a preceding sheet and a subsequent sheet fed after the preceding sheet;
In the control step, when the preceding sheet whose front and back sides have been reversed by the guide section is being conveyed by the conveying roller, an overlapping state is formed in which a leading edge of the succeeding sheet is overlapped with a second surface of the preceding sheet; A control method characterized in that when the leading edge of the subsequent sheet does not reach a predetermined position, recording is performed on the subsequent sheet after the overlapping state is resolved. 21. The preceding sheet on which recording has been performed on the first side is conveyed by the conveyance roller in a direction opposite to the conveyance direction and enters the guide section. control method. In the control step, the overlapping state is formed by continuously driving the feeding roller while the conveying roller is being driven intermittently to convey the preceding sheet. The control method according to any one of items 15 to 21 . The recording device includes a sensor for detecting a sheet between the feeding roller and the conveying roller,
23. The control method according to claim 22 , wherein in the control step, the feeding roller is continuously driven after the leading edge of the subsequent sheet is detected by the sensor. 24. The recording apparatus according to claim 15 , wherein a lever is provided between the feeding roller and the conveying roller to press down the sheet fed by the feeding roller. Control method described in . 25. The recording apparatus further includes a flapper provided between the feeding roller and the conveying roller, the flapper being rotatable by the sheet fed by the feeding roller. The control method according to item 1. 15. In the control step, an amount of overlap between the preceding sheet and the subsequent sheet is determined based on recorded data on at least one of the first side and the second side of the preceding sheet. 26. The control method according to any one of items 25 to 25 . In the control step, an amount of overlap between 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. The control method according to any one of claims 15 to 26 , characterized in that: If the length of the preceding sheet is outside a predetermined range, in the control step, the preceding sheet is ejected without reversing the front and back of the preceding sheet after recording the first side of the preceding sheet. The control method according to any one of claims 15 to 27. A program for causing a computer to execute each step of the control method according to claim 15 . A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to any one of claims 15 to 28 .

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