JP2012180189A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that corrects an interval between a first recording material and a second recording material which are successively conveyed to a prescribed distance when the interval is narrower than a prescribed distance.SOLUTION: When the recording materials for forming images are successively conveyed, the image forming apparatus defines the prescribed distance as the interval between the prior first recording material and the subsequent second recording material. The apparatus includes: a measuring device for measuring a time from the detection of a rear end of the first recording material to the detection of a rear end of the second recording material while the first and second recording materials are conveyed; and a control device for returning the interval between the first and second recording materials to the prescribed distance by performing stop control for stopping only the conveyance of the second recording material for a time of a difference between a threshold and a measured value when a measured value by the measuring device is lower than the predetermined threshold.

Description

  The present invention relates to an image forming apparatus that conveys a recording material on which image formation is performed.

  In general, in an image forming apparatus such as a printer or a copier, it is considered that outputting a printing result earlier is of high quality. Therefore, in the control of the image forming apparatus, it is required to realize a higher printing speed by eliminating useless waiting time or shortening the operation time. As an example of such a technique for improving the printing speed, when a preceding first sheet (an example of a recording material) is being conveyed, the sensor on the conveyance path detects the trailing edge of the first sheet. By starting the conveyance of the subsequent second sheet (while the first sheet is still being conveyed), the printing of the second sheet starts from the end of the printing of the first sheet. There are already known techniques for shortening the time required to increase the printing speed. For example, in Patent Document 1, a sheet trailing edge detection sensor is installed on the conveyance path, and a separation roller (one sheet is separated from the sheet table and conveyed at the timing when the sheet trailing edge sensor detects the trailing edge of the first sheet. A configuration is disclosed in which the roller between the two sheets is started by driving the second sheet to start conveyance of the second sheet, thereby reducing the interval between the two sheets and reducing the printing loss time.

  However, in the recording material conveyance technique described above, the conveyance of the second sheet is only started at the timing when the trailing edge of the first sheet is detected. That is, there is a situation in which the interval between the first sheet and the second sheet becomes narrower than a predetermined distance because the first sheet is skewed after the trailing edge of the first sheet is detected. sell. Therefore, double feeding of the first sheet and the second sheet occurs, and there is a possibility of jamming.

  The present invention has been made in view of the above circumstances, and corrects to a specified distance when the interval between the first recording material and the second recording material that are continuously conveyed is narrower than the specified distance. An object of the present invention is to provide an image forming apparatus.

  In order to achieve such an object, according to an aspect of the present invention, when the recording material on which image formation is performed is continuously conveyed, the interval between the preceding first recording material and the succeeding second recording material is defined. An image forming apparatus that takes a distance, and detects the trailing edge of the second recording material after detecting the trailing edge of the first recording material during conveyance of the first recording material and the second recording material. And a stop control for stopping only the conveyance of the second recording material for the time of the difference between the threshold value and the measured value when the measured value by the measuring means falls below a predetermined threshold value. And a control means for returning the interval between the first recording material and the second recording material to a specified distance.

  According to the present invention, when the interval between the first recording material and the second recording material that are continuously conveyed is narrower than a specified distance, the recording material being conveyed is corrected by correcting the distance to the specified distance. Double feeding and jamming due to the distance between them being too narrow can be prevented.

1 is a schematic configuration diagram illustrating an overall configuration of a mechanism unit of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view illustrating a main part of a mechanism unit of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a configuration and a sheet conveyance path when second and third sheet trays are connected to the image forming apparatus according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a mechanism in which a jam occurs due to paper skew in an image forming apparatus according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a mechanism in which a jam occurs due to paper skew in an image forming apparatus according to an embodiment of the present invention. 3 is a block diagram illustrating a configuration example of a control unit of the image forming apparatus according to an embodiment of the present disclosure. FIG. FIG. 10 is a diagram illustrating Example 1 of sheet interval correction control of the image forming apparatus according to an embodiment of the present invention. FIG. 10 is a diagram illustrating Example 1 of sheet interval correction control of the image forming apparatus according to an embodiment of the present invention. FIG. 10 is a diagram illustrating Example 2 of sheet interval correction control of the image forming apparatus according to an embodiment of the present invention. FIG. 10 is a diagram illustrating Example 3 of sheet interval correction control of the image forming apparatus according to an embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  First, an outline of the present embodiment will be described. The present embodiment has the following characteristics when processing a plurality of sheets (an example of a recording material) that are continuously conveyed. In short, for example, when paper is fed from the third paper tray, the trailing edge sensor of the second paper tray detects the trailing edge of the two sheets and detects the distance between them, thereby detecting the actual two sheets. Know the distance of the paper. Using the result, the operation of the transport roller is controlled to adjust the transport speed of the first or second sheet. By such control, the sheet is returned to a normal distance (a predetermined distance defined in advance; a normal distance), so that double feeding and jamming due to the distance between the two sheets becoming too narrow are prevented. It is characterized by being able to. Such features will be described in detail below using specific examples.

  An example of the image forming apparatus of this embodiment will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG.

  A carriage 33 is slidably held in the main scanning direction by a guide rod 31 and a stay 32, which are guide members horizontally mounted on the left and right side plates 21A and 21B constituting the frame 21, and is not shown by a main scanning motor (not shown). It moves and scans in the direction indicated by the arrow in FIG. 2 (carriage main scanning direction) via the timing belt.

  The carriage 33 is provided with a recording head 34 composed of four droplet ejection heads that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). The outlets are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.

  As an inkjet head constituting the recording head 34, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. It is possible to use a shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet.

  In the present embodiment, in addition to simultaneously driving all the ink discharge ports, the ink discharge ports can be driven divided in time. When all the ink outlets are driven at the same time, there may be disadvantages such as a decrease in recording quality due to the crosstalk between the ink outlets, or a temporary increase in current due to the need for a large current. However, these disadvantages can be avoided by time-division driving.

  A driver IC is mounted on the recording head 34 and is connected to a control unit (not shown) via a harness (flexible print cable) 22.

  In addition, the carriage 33 is equipped with a sub tank 35 for each color for supplying ink of each color to the recording head 34. Each color sub-tank 35 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 via the ink supply tube 36 of each color. The cartridge loading 4 is provided with a supply pump unit 24 for feeding ink in the ink cartridge 10, and the ink supply tube 36 is engaged with the rear plate 21 </ b> C constituting the frame 21 in the middle of turning. It is held by a stop member 25.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. The sheet roller 43 and the sheet feeding roller 43 are opposed to each other, and a separation pad 44 made of a material having a large friction coefficient is provided. The separation pad 44 is urged toward the sheet feeding roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). The transport belt 51 is, for example, a surface layer that is a sheet adsorbing surface formed of a pure resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon using the same material as the surface layer. And a back layer (medium resistance layer, earth layer).

  A charging roller 56 is provided as charging means for charging the surface of the conveyor belt 51. The charging roller 56 is disposed so as to come into contact with the surface layer of the conveyor belt 51 and to be rotated by the rotation of the conveyor belt 51, and applies a predetermined pressing force to both ends of the shaft as a pressing force. The transport roller 52 also functions as an earth roller, and is in contact with the middle resistance layer (back layer) of the transport belt 51 and is grounded.

  In addition, a guide member 57 is disposed on the back side of the conveyance belt 51 so as to correspond to a printing area by the recording head 34. The guide member 57 has an upper surface that protrudes toward the recording head 34 from the tangent line of the two rollers (the conveyance roller 52 and the tension roller 53) that support the conveyance belt 51, thereby maintaining high-precision flatness of the conveyance belt 51. Like to do.

  The conveyance belt 51 rotates in the belt conveyance direction (sub-scanning direction) in FIG. 2 when the conveyance roller 52 is rotationally driven by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a paper discharge roller 63 are provided. The paper discharge tray 3 is provided below the paper discharge roller 62. Here, the height from between the paper discharge roller 62 and the paper discharge roller 63 to the paper discharge tray 3 is increased to some extent in order to increase the amount that can be stored in the paper discharge tray 3.

  In FIG. 1, a duplex unit 71 is detachably mounted on the back surface of the main body of the image forming apparatus. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 2, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. Yes. The maintenance / recovery mechanism 81 includes a cap member (hereinafter referred to as “cap”) 82a to 82d (hereinafter referred to as “cap 82” when not distinguished) and a nozzle surface for capping each nozzle surface of the recording head 34. A wiper blade 83 that is a blade member for discharging, and an empty discharge receiver 84 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. . Here, the cap 82a is a suction and moisture retention cap, and the other caps 82b to 82d are moisture retention caps.

  Then, the waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 81, the ink discharged to the cap 82, the ink attached to the wiper blade 83 and removed by the wiper cleaner, and the idle ejection receiver 84 are idled. The discharged ink is discharged and stored in a waste liquid tank (not shown).

  In addition, as shown in FIG. 2, in the non-printing area on the other side in the scanning direction of the carriage 33, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An empty discharge receiver 88 for receiving the droplets at the time is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the recording head 34.

  Further, a communication circuit unit (interface) such as a USB for transmitting / receiving data to / from the host is provided on the inner rear side of the apparatus main body 1 and constitutes a control unit that controls the entire image forming apparatus. A control circuit board is provided.

  In the ink jet recording apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and the transport belt 51 and the counter roller 46, and the leading end is guided by the conveying guide 47 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a positive voltage output and a negative output are alternately repeated from the AC bias supply unit to the charging roller 56 by a control circuit (not shown), that is, a charging voltage pattern in which an alternating voltage is applied and the conveying belt 51 alternates. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, during printing (recording) standby, the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the recording head 34 is capped by the cap 82 to keep the nozzles in a wet state, thereby preventing ejection failure due to ink drying. . In addition, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the recording head 34 capped by the cap 82 (referred to as “nozzle suction” or “head suction”), and the recovered recording liquid and bubbles are discharged. Perform the action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

  FIG. 3 is a diagram for explaining a configuration and a sheet conveyance path when the second and third sheet trays are connected to the image forming apparatus of the present embodiment described above. This FIG. 3 will be described.

  3, “printer main body” corresponds to the entire image forming apparatus shown in FIG. 1, and “main body paper tray” corresponds to the paper feed tray 2 shown in FIG. As shown in FIG. 3, the image forming apparatus of the present embodiment can connect the second paper tray to the lower part of the printer main body and the third paper tray to the lower part of the second paper tray.

  In FIG. 3, the paper fed from the second paper tray is transported upward through the paper transport path in the second paper tray and enters the transport path of the printer main body. At this time, when the trailing edge of the sheet (the bottom edge of the sheet when transported upward) is detected by the sheet trailing edge sensor of the second sheet tray, the next sheet is fed from the second sheet tray, The conveyance is started. The same applies to paper feeding from the third paper tray.

  4 and 5 are diagrams for explaining a mechanism in which a jam occurs due to paper skew in the configuration of the image forming apparatus according to the present embodiment shown in FIG. 4 and 5 will be described respectively.

  FIG. 4 shows the positional relationship of sheets immediately after the trailing edge of the first sheet fed from the third sheet feeding tray is detected by the trailing edge detection sensor. As shown in FIG. 4, the conveyance of the second sheet is started at the timing when the first sheet is detected by the trailing edge detection sensor. At this time, it is assumed that the distance between the first sheet and the second sheet is a normal distance (a prescribed distance).

  FIG. 5 shows a case where a skew occurs after the trailing edge of the first sheet fed from the third sheet feeding tray is detected by the trailing edge detection sensor. At this time, as shown in the right diagram of FIG. 5, the first sheet is not parallel to the transport path (transport direction) but is inclined. Then, if the sheets are transported to the printer body with the sheets overlapped as shown in the right diagram of FIG. 5, the sheets are folded in a bellows shape and become jammed, which causes a jam.

  FIG. 6 is a block diagram illustrating a configuration example of the control unit of the image forming apparatus of the present embodiment. This FIG. 6 will be described.

  As shown in FIG. 6, the control unit includes a control microcomputer 601 configured by a microcomputer that controls sheet interval correction control (details will be described later) according to the feature of the present embodiment. Although not shown in FIG. 6, the control unit also includes a print control microcomputer configured by a microcomputer that controls print control.

  When there is a print command from the user through the application 98, an OS (for example, GDI (Graphic Device Interface) mounted on Windows (registered trademark)) 99 transmits image data output from the image forming apparatus to the printer driver 100. To do.

  The printer driver 100 converts the image data transmitted from the application 98 into print image data in a format that can be processed by the image forming apparatus main body, and inputs the converted image data to the image forming apparatus via the communication path 101.

  As described above, the control microcomputer 601 uses a carriage drive motor drive circuit 603 that includes a carriage drive motor and a transport motor (not shown) to form an image on the paper 42 based on the printed image data input from the communication circuit 101. In addition, the driving control is performed via the transport motor driving circuit 605, and data for driving the pressure generating means for discharging the droplets of the recording head 34 is generated and given to the head driving circuit 609. .

  The control microcomputer 601 receives a detection signal from a carriage position detection circuit 602 that detects the position of the carriage 33, and the control microcomputer 601 controls the movement position and movement speed of the carriage 33 based on this detection signal. The carriage position detection circuit 602 detects the position of the carriage 33 by, for example, reading and counting the number of slits of an encoder sheet arranged in the scanning direction of the carriage 33 with a photosensor mounted on the carriage 33. The carriage drive motor drive circuit 603 rotates the carriage drive motor in accordance with the carriage movement amount input from the control microcomputer 601 and moves the carriage 33 to a predetermined position at a predetermined speed.

  The control microcomputer 601 receives a detection signal from a conveyance amount detection circuit 604 that detects the movement amount (conveyance amount) of the conveyance belt 51, and the control microcomputer 601 moves the conveyance belt 51 based on this detection signal. And control the moving speed. The carry amount detection circuit 604 detects the carry amount by, for example, reading and counting the number of slits of the rotary encoder sheet attached to the rotation shaft of the carry roller 52 with a photo sensor. The conveyance motor drive circuit 605 rotates the conveyance motor in accordance with the conveyance amount input from the control microcomputer 601 and rotates the conveyance roller 52 to move the conveyance belt 51 to a predetermined position at a predetermined speed. .

  The control microcomputer 601 rotates the sheet feeding roller 43 by giving a sheet feeding roller driving command to the sheet feeding roller driving circuit 610. The control microcomputer 601 rotates the maintenance / recovery mechanism drive motor (not shown) via the maintenance / recovery mechanism drive motor drive circuit 611 to raise and lower the cap 82 and the wiper blade 83.

  The control microcomputer 601 drives and controls the ink supply motor for driving the pump of the supply pump unit 24 via the ink supply motor drive circuit 612, and controls the sub tank 35 from the ink cartridge 10 loaded in the cartridge loading unit 4. Supply ink.

  The control microcomputer 601 includes a detection signal from the sub tank full sensor 613 that detects that the sub tank 35 is full, a detection signal from the cartridge cover sensor 614 that detects opening and closing of the front cover 6 of the cartridge loading unit 4, and the like. Is entered.

  Further, the control microcomputer 601 stores information stored in a non-volatile memory (not shown) which is a storage unit provided for each color of each ink cartridge 10 mounted on the cartridge loading unit 4 through the cartridge communication circuit 615. Are stored in a nonvolatile memory (for example, EEPROM) 616 serving as a main body storage means.

  The control microcomputer 601 acquires a date (year / month / day) and time (hour / minute / second) through an RTC (Real Time Clock) 617.

  In the image forming apparatus according to the present embodiment, control (hereinafter, referred to as sheet interval correction control) for correcting the interval between two conveyed sheets to a specified distance is performed by the control system of FIG. 6 described above. Specific examples of this control will be described below.

[Example 1]
FIG. 7 and FIG. 8 are diagrams for describing control for correcting a paper interval that has become too narrow to a specified distance by temporarily stopping paper feeding of the second paper.

  FIG. 7 is a diagram illustrating an example of the positional relationship of the sheets when the image forming apparatus according to the present embodiment multi-feeds the sheets. In the nonvolatile memory of the image forming apparatus, a threshold value (for example, a specified distance from the trailing edge of the first sheet to the leading edge of the second sheet + the distance (length) in the transport direction of the second sheet) A value indicating a time calculated by dividing by a predetermined normal speed) is stored. The image forming apparatus measures the time from when the trailing edge of the first sheet is detected to when the trailing edge of the second sheet is detected when the sheets are continuously conveyed. Next, when the measured value falls below the threshold value, the image forming apparatus is in a state where the distance between the sheets is narrower than a predetermined distance (for example, a state where sheets are double-fed as shown in FIG. It is determined that the sheet interval correction control is necessary, assuming that the double feed is likely to occur (not shown). It should be noted that after detecting the leading edge of the first sheet, the second sheet is detected after the leading edge of the first sheet is detected without detecting the trailing edge of the first sheet. When a time equal to or longer than a value indicating a predetermined time until the leading edge of the sheet is detected, the image forming apparatus may perform control for stopping the conveyance of all sheets instead of the sheet interval correction control. .

  When the image forming apparatus determines that the sheet interval correction control is necessary, the threshold value and the measured value (the time actually taken from the detection of the trailing edge of the first sheet to the detection of the trailing edge of the second sheet) are calculated. Save the difference in non-volatile memory. Then, as shown in FIG. 8, the image forming apparatus performs control for continuing the driving of the sheet feeding roller of the apparatus body (printer body) and stopping the driving of the sheet feeding roller of the second sheet tray as the sheet interval correction control. . Since the paper feed roller of the apparatus main body transports the first sheet and the paper feed roller of the second paper tray transports the second sheet, the distance between the first sheet and the second sheet is controlled by the above control. Leave. In order to set the distance between the sheets to a normal distance (a prescribed distance), the image forming apparatus sets the above-described “difference between the threshold value and the measured value” as the time for stopping the sheet feeding roller of the second sheet tray. For example, when the measured value is shorter than the threshold value by s seconds (an example of the difference between the threshold value and the measured value), the image forming apparatus continues to drive the paper feed roller of the apparatus main body and continues to drive the second paper tray for s seconds. The drive of the paper feed roller is stopped.

[Example 2]
FIG. 9 is a diagram for describing control for correcting a paper interval that has become too narrow to a specified distance by slowing the paper feed speed of the second paper.

When the image forming apparatus determines that the sheet interval correction control is necessary in the same manner as in Example 1, the sheet feed roller of the apparatus body continues to drive at the normal speed as shown in FIG. The paper feed roller is controlled to be driven at a speed (low speed) slower than the normal speed. Since the paper feed roller of the apparatus main body transports the first sheet and the paper feed roller of the second paper tray transports the second sheet, the distance between the first sheet and the second sheet is controlled by the above control. Leave. Then, in order to set the distance between the sheets to a normal distance (a prescribed distance), the image forming apparatus adjusts the time during which the sheet feeding roller of the second sheet tray is slowed down. The time to slow down can be expressed by the following equation.
((V1-v2) * s) / (| t1-t2 | * d)
v1: Normal driving speed of the sheet feeding roller of the apparatus main body v2: Low speed driving speed of the sheet feeding roller of the second sheet tray s: Threshold value t1: First sheet trailing edge detection time t2: Second sheet trailing edge detection time d : Target distance

[Example 3]
FIG. 10 is a diagram for explaining control for correcting a paper interval that has become too narrow to a specified distance by increasing the paper feed speed of the first paper.

When the image forming apparatus determines that the sheet interval correction control is necessary in the same manner as in Example 1, the sheet feeding roller of the apparatus body is driven at a speed (high speed) higher than the normal speed as shown in FIG. The paper feed rollers of the two paper trays are controlled so as to continue driving at the normal speed. Since the paper feed roller of the main body of the apparatus carries the first sheet and the paper feed roller of the second paper tray carries the second sheet, the distance between the first sheet and the second sheet is controlled by the above control operation. Leave. Then, in order to set the distance between the sheets to a normal distance (a prescribed distance), the image forming apparatus adjusts the time for which the sheet feeding roller of the apparatus main body is made high speed. The speeding up time can be expressed by the following equation.
((V1-v2) * s) / (| t1-t2 | * d)
v1: High-speed driving speed of the sheet feeding roller of the apparatus main body v2: Normal driving speed of the sheet feeding roller of the second sheet tray s: Threshold value t1: First sheet trailing edge detection time t2: Second sheet trailing edge detection time d : Target distance

[Example 4]
It is conceivable that the image forming apparatus tends to have a certain characteristic in the sheet feeding speed and timing for each apparatus. For example, in a certain image forming apparatus, the speed of the paper feeding roller is high, and after the trailing edge of the paper is detected, the paper is fed faster than usual, so the distance between the two papers tends to be short. In order to solve such a variation in the characteristics of each image forming apparatus, the timing of feeding the next sheet is corrected for each image forming apparatus. That is, instead of feeding the second sheet immediately after detecting the trailing edge of the first sheet as described in FIG. 4, in this example, the time from the trailing edge detection of the first sheet is reduced. The second sheet is fed. At this time, the time for delaying paper feed is calculated as follows.
Σ (| t1-t2 |) / N
t1: Time of detecting the trailing edge of the first N sheets of the past N sheets of double feed
t2: Time of detection of the trailing edge of the second sheet in the past N times of double feeding

  As described above, according to the present embodiment, when the interval between the first recording material and the second recording material transported continuously is narrower than the specified distance, the correction is made to the specified distance. Thus, it is possible to prevent double feeding and jamming due to the distance between the recording materials being conveyed being too narrow. As another effect, there is also an effect of reducing variation in distance between recording materials due to characteristics of each image forming apparatus.

  As mentioned above, although embodiment of this invention was described, it is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary.

  For example, the operation in the above-described embodiment can be executed by hardware, software, or a combined configuration of both.

  When executing processing by software, a program in which a processing sequence is recorded may be installed and executed in a memory in a computer incorporated in dedicated hardware. Or you may install and run a program in the general purpose computer which can perform various processes.

  For example, the program can be recorded in advance on a hard disk or a ROM (Read Only Memory) as a recording medium. Alternatively, the program is stored on a removable recording medium such as a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto Optical) disc, a DVD (Digital Versatile Disc), a USB (Universal Serial Bus) memory, a magnetic disc, and a semiconductor memory. It is possible to store (record) temporarily or permanently. Such a removable recording medium can be provided as so-called package software.

  The program may be wirelessly transferred from the download site to the computer in addition to being installed on the computer from the removable recording medium as described above. Or you may wire-transfer to a computer via networks, such as LAN (Local Area Network) and the internet. The computer can receive the transferred program and install it on a recording medium such as a built-in hard disk.

  In addition to being executed in time series in accordance with the processing operations described in the above embodiment, the processing capability of the apparatus that executes the processing, or a configuration to execute in parallel or individually as necessary Is also possible.

  The present invention can be applied to image forming apparatuses such as printers, copiers, multifunction machines, and facsimile machines, and recording material conveying apparatuses in general.

2 Feeding tray 4 Cartridge loading section 10 Ink cartridge 21 Frame 21A, 21B Side plate 21C Rear plate 22 Harness 24 Supply pump unit 25 Locking member 31 Guide lot 32 Stay 33 Carriage 34 Recording head 35 Sub tank 36 Ink supply tube 41 Paper stacking section 42 Paper 45 Guide Member 46 Counter Roller 47 Conveyance Guide Member 48 Holding Member 49 Tip Pressure Roller 51 Conveyor Belt 52 Conveyor Roller 53 Tension Roller 56 Charging Roller 57 Guide Member 61 Separation Claw 62 Paper Discharge Roller 63 Paper Discharge Roller 71 Duplex Unit 72 Manual feed tray 81 Maintenance and recovery mechanism 82 Cap 83 Wiper blade 84, 88 Empty discharge receptacle 89 Opening 98 Application 99 OS (GDI)
DESCRIPTION OF SYMBOLS 100 Printer driver 101 Communication circuit 601 Control microcomputer 602 Carriage position detection circuit 603 Carriage drive motor drive circuit 604 Carry amount detection circuit 605 Carry motor drive circuit 606 Paper size sensor 607 Paper position sensor 609 Head drive circuit 610 Paper feed roller drive circuit 611 Maintenance drive mechanism drive motor drive circuit 612 Ink supply motor drive circuit 613 Sub tank full sensor 614 Cartridge cover sensor 615 Cartridge communication circuit 616 Non-volatile memory 617 RTC

JP 62-116433 A

Claims (4)

An image forming apparatus that takes a specified distance as an interval between a preceding first recording material and a succeeding second recording material when continuously conveying the recording material for image formation,
During the conveyance of the first recording material and the second recording material, the time from when the trailing edge of the first recording material is detected until the trailing edge of the second recording material is detected is measured. Measuring means;
When the measurement value by the measurement means falls below a predetermined threshold value, the second recording material is transported only for the time corresponding to the difference between the threshold value and the measurement value. Control means for returning an interval between one recording material and the second recording material to the prescribed distance;
An image forming apparatus comprising: The control means includes
As an alternative to the stop control,
The first recording material and the second recording are performed by performing a first speed change control in which the speed at which the second recording material is conveyed is lower than the speed at which the first recording material is conveyed. 2. The image forming apparatus according to claim 1, wherein the interval between the materials is returned to the specified distance. The control means includes
As an alternative to the stop control and the first speed change control,
The first recording material and the second recording are performed by performing a second speed change control in which the speed at which the first recording material is conveyed is higher than the speed at which the second recording material is conveyed. 3. The image forming apparatus according to claim 1, wherein the interval between the materials is returned to the specified distance. The control means includes
2. A recording apparatus according to claim 1, wherein a predetermined number of recording material intervals when double feeding has occurred in the past are recorded, and a timing at which conveyance of the second recording material is started is adjusted based on the recording. 4. The image forming apparatus according to any one of items 3.

Images