JP4571094B2 - Image forming apparatus and belt conveying apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus and a belt conveyance device.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine of these, for example, an image forming apparatus using a liquid ejection device is known. Such an image forming apparatus uses a liquid discharge head that discharges liquid droplets of a recording liquid as a recording head, and uses paper (the material is not limited to paper, but includes a medium, a recording medium, a recording medium, a transfer paper, (It is meant to include what are also called transfer materials, recording materials, recording paper, etc.) Recording ink by ejecting ink droplets as recording liquid (synonymous with image formation, printing, printing, printing, etc.) The recording is not limited to a meaningful image such as a character or a figure but includes a case where a meaningless image such as a pattern is formed.) For example, an ink jet recording apparatus is known.

  As such an image forming apparatus, for example, an endless conveyance belt is wound around a driving roller and a driven roller so as to be able to move around, and liquid conveyance is performed while conveying a sheet as a member to be conveyed by the conveyance belt. There is one in which an image is formed by discharging droplets from a head.

  In this case, the driving roller for rotating the conveyor belt is a relatively large roller, and the driven roller for applying tension to the conveyor belt has a relatively small diameter in order to reduce the load on the conveyor belt. Generally, it is composed of rollers. Furthermore, in order to separate the paper from the conveyor belt by curvature separation, the driven roller is constituted by a small-diameter roller.

  On the other hand, the conveyor belt is formed of a flexible material or member that enables smooth circular movement and prevents the belt itself from wrinkling.

  For this reason, when the contact time with the roller having a small diameter is extended while the conveyor belt is stretched, the portion in contact with the roller is wrinkled with an arc corresponding to the roller shape (swells outward). Sometimes. As described above, when the conveying belt has a ridge that rises in an arc shape, the flatness of the sheet decreases when the sheet is conveyed, or an image forming unit such as a head that faces the leading end portion of the sheet riding on the ridge portion, There is a risk of jamming by contacting other members.

Therefore, as described in Patent Document 1 and the like, a guide member (printing receiving member) that supports the conveyance belt so as to push up toward the head at a position facing the head and the conveyance belt (back side of the belt). And a platen, etc.) are arranged to thereby ensure the flatness of the conveyor belt.
JP 2005-313348 A

In addition, as described in Patent Document 2, by using a conveyor belt provided with an electrode plate and applying a voltage to the electrode plate, the conveyor belt is provided on a surface opposite to the recording paper suction surface. In addition, the conveyance belt is slidably adsorbed to the plurality of convex portions, and the paper is electrostatically adsorbed and conveyed to the conveyance belt. In some cases, a voltage is applied to the convex portion so as to be larger than a potential difference between the convex portion and the convex portion, thereby suppressing the influence of the wrinkle shape caused by leaving for a long time and the influence of the fluttering generated during belt conveyance.
JP 2002-284383 A

  In addition, as countermeasures against wrinkles caused by leaving the conveyance belt such as a transfer belt in electrophotography for a long period of time, the diameter of the rollers that apply tension to the belt can be increased, or the tension can be loosened at a level that does not impair the conveyance performance. In addition, a material that does not easily wrinkle (such as CR rubber or polyimide) is used for the base material of the belt.

Other prior literature relating to belts and paper wrinkles includes the following.
JP 2003-335387 A JP 2004-268269 A JP 2000-214693 A Japanese Patent Laid-Open No. 06-038027

  However, as described above, even if the guide belt provided on the back side of the conveyor belt ensures the flatness of the conveyor belt, arc-shaped ridges corresponding to the roller shape partially generated on the conveyor belt itself are formed. There is a problem that it is difficult to eliminate.

  Moreover, in the thing provided with the conveyance belt provided with an electrode plate and the some convex part which adsorb | sucks a belt, there exists a subject that the structure of a conveyance belt becomes complicated.

  The present invention has been made in view of the above-described problems, and provides an image forming apparatus and a belt conveyance device that prevent the leading end portion of a sheet or a member to be conveyed from riding on the ridge portion even if the conveyance belt is wrinkled. The purpose is to do.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Before the conveyor belt and the sheet is opposed, and a belt drive control means is positioned at the predetermined position the part is relative to the at least one roller of said two rollers in stopping of the conveyor belt,
When the leading end portion of the sheet is pressed by the pressing unit at a position downstream of the image forming unit in the sheet conveying direction, a portion facing at least one of the two rollers when the conveying belt is stopped is The structure is configured to face the sheet at a position upstream of the image forming unit in the sheet conveyance direction .

An image forming apparatus according to the present invention includes:
A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
When an image is continuously formed on a plurality of sheets, a position facing at least one roller of the two rollers when the conveying belt is stopped only in relation to the first sheet. It was <br/> configured to.

An image forming apparatus according to the present invention includes:
A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
When the time when the conveying belt is not driven exceeds a predetermined time, a portion of the two rollers that is opposed to at least one of the two rollers when the conveying belt is stopped is set to a position facing the paper.
The configuration.

An image forming apparatus according to the present invention includes:
A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
When the environmental temperature is outside the predetermined temperature range, a portion of the two rollers that is opposed to at least one of the two rollers when the conveyance belt is stopped is set to a position that is opposed to the sheet.
The configuration.

An image forming apparatus according to the present invention includes:
A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
When the paper and the transport belt are opposed to each other, the portion of the two rollers that is opposed to at least one of the two rollers is opposed to the upstream side of the paper in the paper transport direction when the transport belt is stopped. And a belt drive control means for driving the conveyor belt .

The belt conveying apparatus according to the present invention is
A conveyor belt wound between at least two rollers;
When the transported member that is transported by the transport belt is opposed to the transport belt, a portion that is opposed to at least one of the two rollers is opposed to the transported member when the transport belt is stopped. wherein comprising a belt drive control means for driving the conveyor belt, to,
A portion of the two rollers that is opposed to at least one of the two rollers when the conveying belt is stopped when the time during which the conveying belt is not driven exceeds a predetermined time is set to a position that is opposed to the member to be conveyed. The configuration.
The belt conveying apparatus according to the present invention is
A conveyor belt wound between at least two rollers;
When the transported member that is transported by the transport belt is opposed to the transport belt, a portion that is opposed to at least one of the two rollers is opposed to the transported member when the transport belt is stopped. Belt drive control means for driving the conveyor belt,
When the environmental temperature is outside the predetermined temperature range, a portion of the two rollers that is opposed to at least one of the two rollers when the conveyance belt is stopped is set to a position that is opposed to the member to be conveyed.
The configuration.

According to the image forming equipment according to the present invention, the preceding sheet and the conveyor belt is opposed, at least one roller relative to that the belt drive control is positioned at the predetermined position portions of the two rollers in stopping of the conveyor belt And a portion that is opposed to at least one of the two rollers when the conveying belt is stopped when the leading end of the sheet is pressed by the pressing unit at a position downstream of the image forming unit in the sheet conveying direction. A configuration facing the sheet at a position upstream of the image forming unit with respect to the sheet conveyance direction. When an image is continuously formed on a plurality of sheets, at least two rollers when the conveyance belt is stopped only in relation to the first sheet. A configuration in which a portion facing one roller is positioned to face a sheet, when the conveyance belt is not driven for a predetermined time and when the conveyance belt is stopped A configuration in which at least one of the two rollers is opposed to the sheet, and when the environmental temperature is outside a predetermined temperature range, the conveyance belt is stopped when the conveyance belt is stopped. since the portion that has been configured to the position opposite to the sheet, the leading end portion of the sheet can be prevented from rides on parts of the habit of the conveyor belt.
According to the image forming apparatus of the present invention, when the sheet and the conveying belt are opposed to each other, the portion facing at least one of the two rollers when the conveying belt is stopped is more in the sheet conveying direction than the leading end portion of the sheet. Since the belt drive control means for driving the conveyor belt so as to face each other on the upstream side is provided, it is possible to prevent the leading edge of the sheet from running on the ridge portion of the conveyor belt.
According to the belt conveyance device of the present invention, when the conveyance member and the conveyance belt conveyed by the conveyance belt face each other, the portion facing at least one of the two rollers when the conveyance belt is stopped is covered. Belt drive control means for driving the conveyor belt to face the conveyor member is provided, and when the conveyor belt is not driven exceeds a predetermined time, it is opposed to at least one of the two rollers when the conveyor belt is stopped. A configuration in which the portion is positioned relative to the member to be transported, and the portion that is opposed to at least one of the two rollers when the transport belt is stopped when the environmental temperature is outside the predetermined temperature range. Therefore, it is possible to prevent the front end portion of the transported member from riding on the ridge portion of the transport belt.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention including a belt conveyance device according to the present invention will be described with reference to FIGS. 1 is a schematic configuration diagram for explaining the overall configuration of the apparatus, FIG. 2 is an enlarged explanatory view of a belt conveying device portion of the apparatus, and FIG. 3 is an explanatory plan view of a main part of the apparatus.

  As shown in FIG. 2, the image forming apparatus holds a carriage 3 slidably in a main scanning direction by a guide rod 1 which is a guide member horizontally mounted on left and right side plates (not shown) and a guide stay (not shown). The main scanning motor 4 which is a driving motor moves and scans in the direction indicated by the arrow (main scanning direction) in FIG. 2 via the timing belt 5 which is bridged between the driving pulley 5 and the driven pulley 6.

  The carriage 3 includes a recording head 8y serving as an image forming unit including four liquid ejection heads that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). 7m, 7c, 7k (referred to as “recording head 8” when colors are not distinguished) are arranged in a direction (sub-scanning direction) in which a plurality of droplet discharge ports (nozzles) intersect with the main scanning direction. Is attached facing down.

  As an inkjet head constituting the recording head 8, 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. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used. Note that the recording head can also be configured by one or a plurality of liquid ejection heads provided with a plurality of nozzle rows that eject different colors.

  In addition, the carriage 3 is equipped with a head tank 9 for each color for supplying liquid of each color to the recording head 8. The head tank 9 is replenished and supplied with liquid from a main tank (liquid cartridge) via a supply tube (not shown).

  On the other hand, as a paper feeding unit for feeding the paper 12 stacked on the paper stacking unit (pressure plate) 11 of the paper feed tray 10, a half-moon roller (feeding) that separates and feeds the paper 12 from the paper stacking unit 11 one by one. A separation pad 14 made of a material having a large friction coefficient is provided opposite to the (paper roller) 13 and the sheet feeding roller 13, and the separation pad 14 is urged toward the sheet feeding roller 13 side.

  A guide member (not shown) for guiding the paper 12, a registration roller 16, a transport guide member 17, and the like to feed the paper 12 fed from the paper feed unit to the lower side of the recording head 8 and transport it. And a sheet holding member 20 having sheet pressing rollers 18 and 19, and a conveying belt 21 constituting a belt conveying unit for electrostatically attracting the conveyed sheet 12 and conveying it at a position facing the recording head 8. It has.

  The transport belt 21 is an endless belt, and is configured to wrap around a transport roller 22 serving as a driving roller and a tension roller 23 serving as a driven roller, and circulate in the belt transport direction (sub-scanning direction). is doing. This 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, such as ETFE pure material, and resistance control by carbon with the same material as this surface layer. And a back layer (medium resistance layer, ground layer).

  A charging roller 26 is provided as charging means for charging the surface of the conveyor belt 21. The charging roller 26 is disposed so as to come into contact with the surface layer of the conveyor belt 21 and rotate following the rotation of the conveyor belt 21, and applies a predetermined pressing force to both ends of the shaft as a pressing force. A guide member (printing receiving member, platen) that pushes the conveying belt 21 toward the recording head 8 can be disposed on the back side of the conveying belt 21 in correspondence with the printing area by the recording head 8.

  The conveyance belt 21 rotates in the belt conveyance direction (sub-scanning direction) in FIG. 2 when the conveyance roller 22 is rotationally driven by the sub-scanning motor 31 via the drive belt 32 and the pulley 33. In addition, a slit is formed in the shaft 22a of the transport roller 22 and an encoder wheel 34 is attached, and an encoder sensor 35 for detecting the slit of the encoder wheel 34 is disposed, thereby detecting the amount of movement of the transport belt 21. A scanning encoder 36 is configured.

  Further, on the downstream side of the image forming area by the recording head 8, a paper pressing roller 41 that is a pressing means such as a spur is disposed facing the tension roller 23, and the paper 12 to be separated from the conveying belt 21 by the curvature separation is guided. And a paper discharge stack tray 43 on which the paper 12 guided and discharged by the guide member 42 is stacked.

  A duplex unit 50 is mounted on the back side of the apparatus main body. The duplex unit 50 includes sheet reversing rollers 51 and 52. When the conveyance belt 21 reverses after printing on one side is completed, the sheet 12 on which printing on one side is completed is sent to the duplex unit 50, and the reversing rollers 51, 52 The sheet 12 is reversed by 52 so that the other side becomes the printing side, and is fed between the registration roller 16 and the conveying belt 21.

  A multi-manual feed tray 60 can be connected above the duplex unit 50. The multi manual feed tray 60 includes a paper feed roller 63 that feeds sheets 62 stacked on the multi manual feed 61 one by one, a motor (drive source) 65 for rotationally driving the paper feed roller 63, and the motor 65. Are provided with a driving force transmission mechanism 66 for transmitting the rotation of the paper 52 to the paper feed roller 63 and a side fence (not shown) for regulating the side of the paper 52 on the multi manual feed tray 61. The sheet 12 fed from the multi manual feed tray 60 by the sheet feeding roller 63 is fed between the pressing roller 18 and the conveying belt 21.

  Further, as shown in FIG. 1, a paper presence / absence sensor 71 for detecting the presence / absence of the paper 12 is provided in the transport path between the paper feed roller 13 and the registration roller 16, and the carriage 3 has a leading end position of the paper 12. A paper sensor 72 that can be used for both end position detection is provided.

  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 8 is arranged in the non-printing area on one side in the scanning direction of the carriage 3. Yes.

  The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a to 82d (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 8, and nozzle surfaces. A wiper blade 83 that is a blade member for wiping the ink, 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. ing. Here, the cap 82a is a suction and moisture retention cap, and the other caps 82b to 82d are moisture retention caps.

  Further, in the non-printing area on the other side of the carriage 3 in the scanning direction, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 88 is arranged, and the idle discharge receiver 88 is provided with openings 89 a to 89 d along the nozzle row direction of the recording head 31.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. This figure is an overall block diagram of the control unit.
The control unit controls the entire image forming apparatus. The main control unit 101 includes a microcomputer that also serves as a belt drive control unit according to the present invention, and the print control unit 102 includes a microcomputer that controls print control. It has.

  Then, the main control unit 101 sets the main scanning motor 4 and the sub scanning motor 31 to the main scanning motor driving circuit 103 and the sub scanning motor 31 in order to form an image on the paper 12 based on the print processing information input from the communication circuit 100. Drive control is performed via the scanning motor 104, and control such as sending print data to the print control unit 102 is performed.

  A detection signal from a carriage position detection circuit 105 that detects the position of the carriage 3 is input to the main control unit 101, and the main control unit 101 controls the movement position and movement speed of the carriage 3 based on this detection signal. To do. The carriage position detection circuit 105 detects the position of the carriage 3 by, for example, reading and counting the number of slits of an encoder sheet arranged in the scanning direction of the carriage 3 with a photosensor mounted on the carriage 3. The main scanning motor driving circuit 103 rotates the main scanning motor 4 according to the carriage movement amount input from the main control unit 101 to move the carriage 3 to a predetermined position at a predetermined speed.

  Further, a detection signal from a conveyance amount detection circuit 106 that detects the movement amount of the conveyance belt 21 is input to the main control unit 101, and the main control unit 101 detects the movement amount and movement speed of the conveyance belt 21 based on this detection signal. To control. The carry amount detection circuit 106 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 22 with a photo sensor. The sub-scanning motor driving circuit 104 rotates the sub-scanning motor 31 in accordance with the conveyance amount input from the main control unit 101, rotationally drives the conveyance roller 22, and moves the conveyance belt 21 to a predetermined position at a predetermined speed. Move.

  Further, the main control unit 101 performs control for charging the conveyance belt 21 by applying an AC bias to the charging roller 26 via the AC bias supply unit 107.

  Further, the main control unit 101 rotates the sheet feeding roller 13 once by giving a sheet feeding roller driving command to the sheet feeding roller driving circuit 108. The main control unit 101 rotationally drives a motor (not shown) of the maintenance / recovery mechanism 81 via the maintenance / recovery mechanism drive motor drive circuit 109, thereby raising and lowering the cap 82, raising and lowering the wiper blade 83, and driving a suction pump (not shown). And so on.

  Further, the main control unit 101 receives the detection signals from the paper presence sensor 71 and the paper sensor 72 described above, detects the presence / absence of the paper 12, the leading edge position, etc. from both or any of the detection signals. The conveyance of the paper 12 to the printing position (image forming area by the recording head 8) is controlled according to the detection result.

  Further, the main control unit 101 takes in information stored in the non-volatile memory 116 provided in each liquid cartridge attached to a cartridge loading unit (not shown) through the cartridge communication circuit 114, performs a necessary process, It is stored and held in a non-volatile memory (for example, EEPROM) 115 which is a main body storage means.

  Further, the main control unit 101 receives a detection signal from an environmental sensor 113 that detects environmental temperature and environmental humidity.

  The print control unit 102 generates pressure for ejecting droplets of the recording head 8 based on the signal from the main control unit 101 and the carriage position and conveyance amount from the carriage position detection circuit 105 and the conveyance amount detection circuit 106. Data for driving the means is generated, and the above-described image data is transferred to the head drive circuit 110 as serial data, and the transfer clock, latch signal, and droplet control necessary for transferring the image data and confirming the transfer, etc. In addition to outputting a signal (mask signal) etc. to the head drive circuit 110, it is composed of a D / A converter, a voltage amplifier, a current amplifier, etc. for D / A converting the pattern data of the drive signal stored in the ROM. Drive waveform generator and drive waveform selection means to be given to the head driver, one drive pulse (drive signal) or a plurality of drive pulses And it generates and outputs a composed drive waveform (drive signal) to the head drive circuit 110.

  The head drive circuit 110 selectively selects a drive signal constituting a drive waveform supplied from the print control unit 102 based on image data corresponding to one row of the print head 8 that is serially input. The recording head 8 is driven by applying it to a driving element (for example, a piezoelectric element as described above) that generates energy for discharging the ink. At this time, by selecting a driving pulse constituting the driving waveform, for example, dots having different sizes such as large droplets (large dots), medium droplets (medium dots), and small droplets (small dots) can be distinguished. it can.

  In the image forming apparatus configured as described above, the sheets 12 are separated and fed one by one from the sheet feeding unit, and the fed sheets 12 are guided by the conveyance guide and are conveyed by the conveyance belt 21 facing the conveyance roller 22. After the tip position is adjusted between the portion and the registration roller 16, the direction is changed by about 90 °, and the recording head 8 is sent out from between the pressing roller 18 and the conveying belt 21 and is pressed by the pressing roller 19. Is sent out toward the image forming area.

  Therefore, the paper 12 is sent and stopped, and the recording head 8 is driven in accordance with the image signal while moving the carriage 3, thereby ejecting ink droplets onto the stopped paper 12 to record one line. When the recording for one line is completed, the conveying belt 21 is driven to feed the paper 12 by a predetermined feed amount (predetermined line feed amount), and the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 12 has reached the recording area, the recording operation is finished, and the paper 12 is discharged onto the paper discharge stack tray 28.

Next, drive control of the conveyor belt in this image forming apparatus will be described with reference to FIG.
First, the generation of wrinkles on the transport belt will be described. As described above, when transported members such as paper are transported by the transport belt, in order to ensure the flatness of the transported member, It is important to maintain a tensioned state. Further, the conveyor belt is formed of a flexible material or member to enable smooth circumferential movement and to prevent the belt itself from wrinkling.

  On the other hand, the driving roller for rotating the conveyor belt is a roller having a relatively large diameter, and the driven roller for applying tension to the conveyor belt is a roller having a relatively small diameter in order to reduce the load on the conveyor belt. Generally, it is composed of Furthermore, in order to separate the paper from the conveyor belt by curvature separation, the driven roller is constituted by a small-diameter roller.

  Therefore, for example, as shown in FIG. 5, when the conveyor belt 21 stretched around the conveyor roller 22 and the tension roller 23 is placed in a stopped state, the portion in contact with the tension roller 23 has a roller shape. Correspondingly, a ridge 200 that swells in an arc shape, that is, bulges outward, may be attached. Thereafter, when the conveyor belt 21 is moved, the ridge 200 generated on the conveyor belt 21 moves as shown in FIG. It will be.

  For this reason, as shown in FIG. 7, when the ridge 200 of the conveying belt 21 is increased, the surface (nozzle surface) 8a on which the nozzles of the recording head 8 are formed and the sheet conveying surface are a minute interval of about 1 mm. , The ridge 200 may contact (interfere) with the nozzle surface 8 a of the recording head 8. Further, as shown in FIG. 8, when the leading end portion 12a of the sheet 12 (shown by a broken line for convenience) sent to the conveying belt 21 is conveyed in a state of riding on the ridge 200 portion of the conveying belt 21, The leading end portion 12a of the paper 12 may come into contact (interference) with the nozzle surface 8a of the recording head 8 to cause a jam. In particular, when the paper 12 is pressed by the paper presser roller 19 on the front side of the recording head 8, the leading end portion 12 a of the paper 12 is warped against the flange 200, and the leading end portion 12 a of the paper 12 is warped by the recording head 8. It becomes easy to contact (interfere) with the nozzle surface 8a.

An example of wrinkle position control for positioning the wrinkle portion of the conveyor belt at a predetermined position before image formation performed by the main control unit will be described with reference to FIG.
When the main body of the apparatus is turned on, the main control unit 101 performs necessary initial processing. As part of this initial processing, the main control unit 101 rotates the transport roller 22 to move the transport belt 21 by a predetermined amount of movement (predetermined amount). Then, the conveyor belt 21 is stopped at a position where the portion (the flange portion) facing the tension roller 23 becomes the “predetermined position” when the conveyor belt 21 is stopped. At this time, the paper 12 is not fed from the paper feed tray 10.

  Thereafter, if there is a print request, the driving of the conveying belt 21 is started, the sheet 12 is fed from the sheet feeding tray 10, and the sheet 12 is fed onto the conveying belt 21. As described above, the recording head 8 If the printing process (printing process) for forming an image on the paper 12 by intermittently transporting the scanning and the paper 12 is executed, and if the continuous printing is to continuously print on a plurality of pages, the printing process is repeated. If there is no print request, the process proceeds to other processing.

  When such processing is performed, the operation of stopping the conveyor belt 21 at a predetermined position before feeding the paper 12 is executed only before the first print (printing of the first paper) after the power is turned on. Become. Therefore, when an image is continuously formed on a plurality of sheets, the drive control is performed so that the portion facing the driven roller at a stop of the conveying belt is in a predetermined position only by the relationship with the first sheet. Such control is performed because in continuous printing, the printing speed is improved by feeding and transporting a plurality of sheets 12 with as much space between the sheets as possible. In the case of continuous printing, the transport belt 21 is moved to a predetermined position. This is because if the operation of stopping at this time is performed, the printing speed is reduced accordingly. Of course, it is also possible to perform an operation of stopping the conveyor belt 21 at a predetermined position for each sheet in relation to the required printing speed.

Therefore, the “predetermined position” for stopping the portion facing the tension roller 23 when the conveying belt 21 is stopped will be described.
The “predetermined position” means at least a portion that is opposed to at least one roller (a roller having a relatively small diameter, here a driven roller) when the conveyance belt is stopped when the sheet and the conveyance belt are opposed to each other (癖Is a position facing a portion other than the leading end portion of the sheet.

  For example, as shown in FIG. 10, when the paper 12 fed from the paper feed tray 10 faces the transport belt 21, the portion facing the driven roller 23 when the transport belt 21 stops (the portion where the ridge 200 is generated). , Which is also referred to as a heel portion 200) is a position where the portion of the paper 12 is opposed to a portion other than the leading end portion 12a. At this time, the conveyance belt 21 is stopped in a state where the ridge 200 of the conveyance belt 21 before feeding is positioned at the ridge 200 ′ indicated by the phantom line.

  The “predetermined position” refers to the distance from the ridge 200 of the conveyor belt 21 to the registration roller 16, the conveyance speed (movement speed), the drive start timing of the conveyance belt 21, and the sheet 12 feed start position to the registration roller 16. Since the position is relatively determined by the relationship between the distance, the conveyance speed (paper feeding speed), the driving start timing of the paper feeding roller 13, and the like, the position is not limited to the position of the ridge 200 ′ in FIG.

  In this way, at least when the paper and the transport belt are opposed to each other, the portion facing the roller when the transport belt is stopped (the portion where wrinkles are generated) is positioned so as to be opposed to the portion other than the front end portion of the paper. By positioning the transport belt, it is possible to prevent the front end portion of the sheet from being transported in a state of riding on the ridge of the transport belt and coming into contact with the image forming unit or other members.

  Further, the “predetermined position” can be a position at which a wrinkle portion (a wrinkle portion) of the conveyor belt is opposed to a portion other than a front end portion and a rear end portion of the paper (referred to as an intermediate portion in the present invention). . In other words, when the paper is conveyed with the rear end portion of the paper riding on the flange 200 of the conveyance belt 21, the rear end portion of the paper 12 may jump when the paper 12 cannot be pressed by the pressing roller 19 or the like. Since it may be raised (become warped) and come into contact with the nozzle surface 8a of the recording head 8, it is preferable that the flange portion of the conveyor belt does not face the rear end portion.

  Further, as shown in FIG. 11, the “predetermined position” is a recording in which the portion of the ridge 200 is the image forming means when the leading end portion 12a of the paper 12 is pressed by the pressing roller 41 on the paper discharge side. A position upstream of the head 7 in the sheet conveyance direction, in this example, a position facing the sheet 12 between the pressing rollers 18 and 19 can be used.

  This position will be described. For example, as shown in FIG. 12, the conveyor belt 21 is positioned so that the collar 200 of the conveyor belt 21 has the positional relationship shown in FIG. In order to start printing, the conveyance belt 21 is driven and the feeding of the paper 12 from the paper feed tray 10 is started, so that as shown in FIG. 11), the paper 12 is conveyed with the relationship between the flanges 200 of the conveyor belt 21 facing each other, and the leading end portion of the paper 12 is pressed by a pressing roller 41 on the paper discharge side, as shown in FIG.

  In this case, at a timing at which an image is formed by the recording head 8 at a position where the ridge 200 portion of the conveyance belt 21 faces, the ridge 200 is crushed by the tension of the conveyance belt 21, and the leading end portion of the paper 12 is pressed by the pressing roller 41. In addition to being pressed by the pressing rollers 18 and 19, the flange 200 portion of the conveyor belt 21 is crushed (shown by reference numeral 201), and the paper 12 is placed on the recording head 8. Contact with the nozzle surface 8a can be prevented, jamming can be prevented, flatness can be ensured, and image quality can be improved.

  Further, as in the embodiment described above, the wrinkle 200 generated when the conveyor belt 21 is stopped can be reduced to some extent by performing idling of the conveyor belt 21 after the power is turned on (or before printing is started). It is possible to reduce the occurrence of jam and image degradation.

Next, another example of wrinkle position control performed by the main control unit to position the wrinkle of the conveyor belt at a predetermined position will be described with reference to FIG.
In this process, when waiting for a predetermined period of time to elapse without a print request after the power is turned on, the idling process of the conveyor belt 31 and the process of stopping the conveyor belt 31 at a predetermined position are performed again. Accordingly, even when wrinkles occur due to the conveyance belt not being driven for a long time after the power is turned on, it is possible to prevent the occurrence of jamming or image deterioration due to contact with the image forming means or other members.

  In this case, when the standby time has passed a predetermined time, an idle rotation process of the conveyor belt 31 and a process of stopping the conveyor belt 31 at a predetermined position are performed. It is possible to reduce wrinkles just by performing the idling process of the belt 31.

  Further, when the conveyance belt is idled as in the present embodiment, a time during which the conveyance belt 21 is not driven (a downtime during which no image is formed) is measured, and a sheet is fed according to the length of the downtime. It is also possible to set whether or not to perform idling before feeding, and the idling amount when performing idling.

Next, still another example of wrinkle position control performed by the main control unit to position the wrinkle of the conveyor belt at a predetermined position will be described with reference to FIG.
In this process, after the power is turned on, the environmental temperature is detected, and when the environmental temperature is outside the predetermined temperature range, the conveyance belt 31 is stopped at the predetermined position (the heel 200 becomes the predetermined position). It is.

  When the relationship between the ease with which the ridgeline 200 of the conveyor belt 21 is attached (which means that both the case where the crease is generated from the state where it is not present and the case where the crease is difficult to disappear) and the environmental temperature is seen, it is relatively high. At a temperature, the conveyor belt 21 tends to stretch, and at a relatively low temperature, the conveyor belt 21 tends to harden as it is when the bag 200 is attached.

  Accordingly, when the environmental temperature T is not less than the temperature TL and not more than the temperature TH (TL ≦ T ≦ TH), it is assumed that the belt 200 cannot be reduced to the extent that the bag 200 is not affected by the idling of the conveyor belt 21. 21 is stopped at a predetermined position (the heel 200 becomes a predetermined position).

  As a result, it is possible to prevent the time until the printing can be started after the power is turned on from becoming unnecessarily long.

  Here, the process of stopping the conveyor belt 21 at a predetermined position after power-on is performed based on the environmental temperature. However, the number of idling of the conveyor belt 21 is set based on the environmental temperature. It is also possible to perform idling as many times as possible. For example, as described above, processing such as relatively increasing the number of idling operations can be performed at an environmental temperature at which the conveyance belt 21 is likely to be wrinkled. In this way, printing can be started after the power is turned on. Can be prevented from becoming unnecessarily long.

  In the above-described embodiment, an example is described in which the collar portion of the transport belt 21 is stopped at a predetermined position. However, the present invention is not limited to the stop. That is, as described above, when the conveyance belt and the paper face each other, the timing is such that the collar portion of the conveyance belt is positioned at a position where the collar portion is opposed to a portion other than the leading edge portion of the paper (referred to as simultaneous). This means not the meaning but the timing of the above relationship.) If the sheet feeding from the sheet feeding tray is performed, it is not necessary to stop the conveyor belt at the position where the collar portion becomes a predetermined position.

  In the above-described embodiments, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration and a belt conveyance device thereof. The same can be applied to a belt conveyance device using a belt.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. It is an expansion explanatory view of the belt conveyance device part of the device. It is principal part plane explanatory drawing of the apparatus. 3 is a block explanatory diagram illustrating a schematic configuration of a control unit of the apparatus. FIG. It is explanatory drawing with which it uses for description of generation | occurrence | production of the wrinkle of a conveyance belt. It is explanatory drawing with which it uses for description of the state which the heel moved from the state of FIG. FIG. 4 is an explanatory diagram for explaining a state in which a wrinkle of a conveyance belt is in contact with a recording head. FIG. 6 is an explanatory diagram for explaining a state in which a front end portion of a sheet riding on a ridge of a conveyance belt is in contact with a recording head. It is a flowchart with which it uses for description of an example of the wrinkle position control which positions the wrinkle of the conveyance belt which a main control part performs in a predetermined position. It is explanatory drawing with which it uses for description of a predetermined position. It is explanatory drawing with which it uses for description of the other example of a predetermined position. It is explanatory drawing with which it uses for description of the position of a collar when the conveyance belt used for description of the example of FIG. 11 is made into the predetermined position. FIG. 13 is an explanatory diagram for explaining a halfway process in which a sheet is fed from the state of FIG. 12 and conveyed in a state opposed to the conveying belt. It is a flowchart with which it uses for description of the other example of the wrinkle position control which positions the wrinkle of the conveyance belt which a main control part performs in a predetermined position. It is a flowchart with which it uses for description of the further another example of the wrinkle position control which positions the wrinkle of the conveyance belt which a main control part performs in a predetermined position. It is explanatory drawing with which it uses for description of environmental temperature and the easiness of a wrinkle of a conveyance belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Carriage 8 ... Recording head 10 ... Paper feed tray 11 ... Paper stacking part 12 ... Paper 16 ... Registration roller 18, 19 ... Paper pressing roller 21 ... Conveyance belt 22 ... Conveyance roller 23 ... Driven roller 28 ... Discharge stack tray 31 ... sub-scanning motor 41 ... pressing roller 101 ... main control unit 200 ... 癖

Claims (7)

A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
When the leading end portion of the sheet is pressed by the pressing unit at a position downstream of the image forming unit in the sheet conveying direction, a portion facing at least one of the two rollers when the conveying belt is stopped is An image forming apparatus, wherein the image forming apparatus is opposed to the sheet at a position upstream of the image forming unit in the sheet conveyance direction. A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
When an image is continuously formed on a plurality of sheets, a position facing at least one roller of the two rollers when the conveying belt is stopped only in relation to the first sheet. An image forming apparatus. A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
An image characterized in that when the time when the conveying belt is not driven exceeds a predetermined time, when the conveying belt is stopped, a portion facing at least one of the two rollers is set to a position facing the paper. Forming equipment. A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
Belt drive control means for positioning a portion of the two rollers facing the at least one roller at a predetermined position when the conveyance belt is stopped before the paper and the conveyance belt are opposed to each other;
An image forming apparatus, wherein when the environmental temperature is outside a predetermined temperature range, at least one of the two rollers is opposed to the sheet when the conveyance belt is stopped. A conveyor belt wound between at least two rollers;
Image forming means for forming an image on paper conveyed by the conveying belt;
When the conveyor belt and the paper are relatively, the opposing two of the at least one portion that is relative to the roller the sheet conveying direction on the upstream side than the tip portion of the paper roller during stop of the conveyor belt an image forming apparatus characterized by comprising the belt drive control means for driving the conveyor belt, a so. A conveyor belt wound between at least two rollers;
When the transported member that is transported by the transport belt is opposed to the transport belt, a portion that is opposed to at least one of the two rollers is opposed to the transported member when the transport belt is stopped. wherein comprising a belt drive control means for driving the conveyor belt, to,
A portion of the two rollers that is opposed to at least one of the two rollers when the conveying belt is stopped when the time during which the conveying belt is not driven exceeds a predetermined time is set to a position that is opposed to the member to be conveyed. A belt conveyance device. A conveyor belt wound between at least two rollers;
When the transported member that is transported by the transport belt is opposed to the transport belt, a portion that is opposed to at least one of the two rollers is opposed to the transported member when the transport belt is stopped. Belt drive control means for driving the conveyor belt,
When the environmental temperature is outside the predetermined temperature range, a portion of the two rollers that is opposed to at least one of the two rollers when the conveyance belt is stopped is set to a position that is opposed to the member to be conveyed.
A belt conveyance device.

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