JPH0930041A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate image shift by providing a charge means electrostatically attracting a recording material to a belt like feed member by charging action and performing the electrostatic attraction by the charging means by charge potential higher than that in the continuous feed of one image forming means in the intermittent feed of other image forming means. SOLUTION: A fed recording material P is introduced into the nip part of a pair of resist rollers 113a, 113b to be gradually corrected and a belt 104 is almost driven so as to make one rotation by a drive roller 136 simultaneously with the application of charge to attraction corona 121 to charge a belt 141 over the entire region thereof. A pair of the resist rollers 113a,113b are driven and, in a state corrected in gradual feed, a recording material P passes a corona 114, and a feed guide 115 and the leading end thereof is fed to the position of the corona 116 in a process cartridge 102 arranged at the position opposed through a belt follower roller 137 and the belt 104 at the position of a corona 106 is charged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of image forming means of different image forming systems.

[0002]

2. Description of the Related Art Image forming apparatuses frequently used in offices and the like, particularly copying machines and printers, are required to be compact, sophisticated, and have high image quality.
The demand for colorization is increasing. Well-known image forming methods of image forming apparatuses include an electrophotographic method and an inkjet method. The former electrophotographic method is
For example, after a toner image is formed on the photosensitive drum by a charging unit, an exposing unit, and a developing unit arranged around the photosensitive drum, and the toner image is transferred onto a recording medium (hereinafter referred to as “recording material”) by the transferring unit. Although it is a method of fixing with a fixing means, it is possible to form a high-quality image at a high speed, while a single-color machine could be configured as a small desktop type, but with the increase in color, its size is increased.
High cost is a problem. On the other hand, the latter inkjet method is a method of forming an ink image by directly adhering the ink on the recording material by ejecting the ink from the recording head, and while it is possible to make the entire apparatus compact, the electrophotographic method is used. In comparison, the image forming speed is low and the image quality is degraded in both the monochromatic machine and the color machine. In particular, with regard to the Bunyu image, there is a problem that when the character image is superimposed on the color image, the characters may be blurred. Therefore, in order to solve these problems, an image forming apparatus provided with an electrophotographic image forming unit and an inkjet image forming unit is proposed in, for example, Japanese Patent Application Laid-Open No. 58-168057. In these image forming apparatuses, a black-and-white image mainly composed of character images, which is frequently used in general offices, is formed by an electrophotographic method, and a less frequently used color image is formed by an inkjet method. In addition, each image forming method is properly used. This proper use makes it possible to configure an image forming apparatus most suitable for an office or the like. That is, the image forming apparatus combining the above two image forming methods is a single image forming apparatus, the size of the entire apparatus is minimized, the monochrome image is formed quickly and neatly, and the color image is formed as necessary. Images can also be formed.

A conventional example will be described below with reference to the drawings. FIG. 8 shows an overall configuration diagram of a conventional image forming apparatus.
The image forming apparatus shown in FIG. 1 has at least two image forming means having different image forming systems, and forms an image on the recording material P by these image forming steps. The configuration will be described with reference to the drawings. Reference numeral 801 denotes the image forming apparatus of the present invention. In this apparatus, there is a recording material cassette 805 in which a recording material P is mounted, a belt 804 which is a belt-shaped conveying member is provided downstream thereof, and a process cartridge 802 having an electrophotographic image forming means incorporated on the upper surface thereof, and further. A full-color inkjet image forming unit 803 of the second image forming unit is provided downstream thereof. A fixing device 839 is arranged downstream of the inkjet image forming unit 803. The belt 804 has an annular shape. The details will be described below. In the image forming apparatus 801 of the present invention, the recording material P loaded in the cassette 805 is in contact with the separation claw 812 by the pressure spring 810 via the pressure plate 807. The pressure plate 807 is rotated by a bearing portion 808 depending on the amount of the recording material P loaded. The pressure spring 810 is positioned by the protrusion 809 at the bottom of the pressure plate 807. A sheet feeding roller 811 having a substantially half-moon shape is provided above the cassette 805.
When 1 is rotationally driven in the direction of the arrow in the figure by the drive system shown in the drawing, the recording material P is fed and separated into one sheet by the separation claw 812. After that, a pair of registration rollers 813a and 813b
And is guided to the roller 816 by the roller 814 and the paper guide 815. Meanwhile, the belt 804
Is supported by two rollers, a belt drive roller 836 and a belt driven 837, so as to be rotationally driven in the direction of the arrow in the figure. The drive roller 836 is driven by a drive system (not shown), The roller 837 is driven by the belt. A rubber layer 836a is formed on the surface of the driving roller 836, which has a friction coefficient for transmitting an appropriate driving force for driving the belt 804, and faces a separating corona 834 described later. In order to use, the rubber layer 836a has a volume resistance value of medium resistance, and the core material 836b thereof is a conductor such as metal.
The tension of the belt 804 is given to the driven roller 837 by a tensioner (not shown) so that the tension of the belt 804 becomes appropriate when driven by the driving roller 836. Further, the adsorption corona 8 for charging the belt 804 and adsorbing the recording material P on the belt 804.
21 is provided near the belt 804. The process cartridge 802, which is the first image forming unit, includes a photosensitive drum 818, a primary charging roller 819, and a developing sleeve 817. Further, toner (not shown) and its stirring mechanism, a cleaning blade of the photosensitive drum, and a waste toner container are provided. It is composed by. Further, the roller 816 described above is installed on the exterior portion of the process cartridge 802. Further, in order to transfer the toner image developed on the photosensitive drum 818 onto the recording material P at a position facing the photosensitive drum 818 across the belt 804, the belt 80 is transferred.
A transfer corona 820 that applies an electric charge to No. 4 is installed. Photosensitive drum 8 in the process cartridge 802
A transfer unit 820 is installed at a position opposite to the belt 804 with respect to the belt 18. The exposure of the photosensitive drum 818 is performed by the scanner 826. A polygon mirror 828, which is rotationally driven by a motor (not shown), is provided inside the scanner 826. The polygon mirror 828 can scan the photosensitive drum 818 with laser light emitted from a laser unit (not shown) having a built-in semiconductor laser. It is like this. This laser light is focused by the fθ lens 827 on the surface of the photosensitive drum 818 into a fine spot having a diameter of several tens of μm. In addition, the fθ lens 8
The laser light transmitted through 27 is guided onto the photosensitive drum 818 by the bending mirror 824.

Next, the ink jet image forming section 803 which is the second image forming means will be described. The inkjet image forming unit 803 has a structure in which a head 832 and an ink tank 833 are mounted in a carriage 829, and the carriage 829 has two rails 83.
It is supported by 0 and 831 so as to be movable in a direction perpendicular to the conveyance direction of the recording material P in the drawing. The ink tank 833 has four color ink tanks of cyan, magenta, yellow, and black, and the ink tanks can be exchanged individually for each color. Therefore, the head 832 is divided into four heads corresponding to the above four colors, and the image is formed on the recording material P conveyed by the belt 804 in a non-contact manner. Further, a recovery means for the head 832 (not shown) is provided. In the figure, a separation corona 834 for separating the recording material P from the belt 804 is provided downstream of the inkjet image forming unit 803, and a separation claw 835 is provided downstream of the lower part thereof. The recording material P separated by the separation claw 835 is guided to the fixing device 839 by the pre-fixing guide 838. The fixing device 83
Reference numeral 9 denotes a heat roller 840 and a pressure roller 8 having a built-in heater.
In the nip portion of the two rollers, the heat fixing of the ink and the toner image-formed on the recording material P is performed at the same time. The pressure roller 8
Reference numeral 41 is pressed against the heat roller 840 by a spring (not shown). In the fixing device 839, guides 842 and 843 are provided downstream of the nip portion between the heat roller 840 and the pressure roller 841. The guides 842 and 843 are guided by the guide rollers 842 and 843 and discharged downstream by the discharge roller 844 and the discharge roller 845. Then, by the flapper 846 and the guides 847a and 847b, the curl removing roller 849 and the curl removing rollers 850 and 851 are provided.
Transported to The decurling rollers 850 and 851 are mounted on a holder 854, and the holder 854 is pressed against a decurling roller 849 together with the holder 854 by a spring 154a, so that decurling can be performed. The recording material P discharged by the curl removing means is also used as a stacker 8 by the exterior part of the apparatus.
The face 52 is discharged face down.
Further, in the figure, reference numeral 853 denotes a manual feeding port, which is used when it is desired to form an image on a recording material such as thick paper or thin paper which is difficult to feed in a cassette. After fixing, when the paper guides 847a and 847b are difficult to convey due to thick paper or the like, the flapper 846 can be rotated by the bearing portion 846a and discharged to the face-up discharge port 848.

The operation of the conventional example having the above configuration will be described. The image forming apparatus 801 of the conventional example is configured as a printer. Color or monochrome image data of a computer, a current reading scanner, or the like (not shown) is converted into a monochrome image such as a color image and characters by a controller (not shown). And are connected in a separated state. As a result, the monochrome image is processed by the electrophotographic process cartridge 8 which is the first image forming means.
An image is formed by the image forming apparatus 02, and a color image is formed by the inkjet image forming unit 803 which is the second image forming unit. Therefore, when an image forming command is issued from the controller, the feeding roller 811
Is driven in the direction of the arrow in the figure, one recording material P is fed,
It rushes into the nip portion of the pair of registration rollers 813a and 813b and temporarily stops. Before and after the feeding, the photosensitive drum 818 in the process cartridge 802 is pre-rotated, and the driving roller 836 is also driven in synchronization with this, and the belt 804 is also driven. At this time, the suction corona 821 is charged so that the belt 804 can be charged, and the charged portion is driven until it reaches the roller 814 from the position of the suction corona 821 through the driving roller 836. Registration roller pair 8 upon arrival
When 13 is rotationally driven and the conveyance is restarted, the recording material P starts to be attracted from the vicinity of the nip between the roller 814 and the belt 804, and the recording material is conveyed. As a result of the suction, the recording material P conveyed moves past the roller 816 and is the process cartridge 802 which is the first image forming means.
It is guided to the photosensitive drum 818 inside. At this time, the photosensitive drum 818 is continuously driven at a predetermined process speed in a state where the toner is not developed, and therefore, the toner is not transferred to the recording material P and the first image forming unit 802 is not performed.
Pass through. Next, the recording material P is continuously electrostatically attracted onto the belt 804 and is continuously conveyed.
Inkjet image forming section 8 which is the second image forming means
03, the leading edge position of the recording material P is detected by a recording material sensor (not shown), and the recording material P is driven under the head portion 832 in the inkjet image forming unit 803 to the image forming start position for the recording material P. After that, the carriage 829 is temporarily stopped, and at a certain timing, the carriage 829 reciprocates in a direction perpendicular to the recording material conveyance direction to perform main-scan recording for one line, and when that is completed, the belt 804 is driven by intermittent feeding. Then, the recording material is conveyed by one step in the sub-scanning direction. The recording material P is conveyed by the intermittent feeding (sub scanning) of the belt 804 and the reciprocating feeding (main scanning) of the carriage 829.
Then, the inkjet image forming unit 803 sequentially forms images. The leading end of the recording material P reaches the outer diameter portion of the drive roller 836, and thereafter, the recording material P is conveyed along the outer diameter portion of the roller 836 by the electrostatic attraction, and the above two types of image formation are performed. The process cartridge 802 and the inkjet image forming unit 803, which are means, are conveyed to the belt unit 804a on the opposite side. After that, when the trailing end of the recording material P passes through the head 832 and the image formation by the inkjet image forming unit 803 is completed, the belt 804 is continuously driven again by the driving roller 836, and the recording material P is moved by the driven roller 837. It is conveyed again through the outer diameter portion to the process cartridge 802 which is the first image forming means. At this time, an image is formed by the process cartridge 802 and the transfer corona 820, and the toner is transferred onto the recording material P to form a monochrome image. Then, the recording material P reaches the inkjet image forming unit 803 which is the second image forming unit, and at this time, the inkjet image forming unit 80.
In No. 3, the image is not formed and the sheet passes under the head 832 while being continuously fed. When the leading edge of the recording material reaches the separation corona 834 by the above-described conveyance, a separation bias charge is generated for the recording material P, and the recording material P is rotated by the curvature of the outer diameter portion of the driving roller 836 and the separation claw 835. It is separated from 804, conveyed to the pre-fixing guide 838, reaches the fixing device 839, and the heat roller 840 and the pressure roller 841 dry the ink at the same time as the toner and the fixing. The recording material P on which the above-mentioned fixing has been carried out includes a pair of discharge rollers 844 and 845, a flapper 846, a paper guide 847.
a, 847b, curl removing roller pair 849, 850, 8
The sheet 51 is discharged to the stacker 852. Also,
Even if the image information from the controller (not shown) is monochrome or color only, the process is the first image forming means when the image formation is carried out by exactly the same recording material conveyance as described above and monochrome is only. Image formation is performed only by the cartridge 802, and in the case of color only, image formation is performed only by the inkjet image forming unit 803 which is the second image forming means. The above is the configuration and operation of the conventional example. The outer peripheral length of the annular belt is set to be longer than the length of the recording material used in the conveying direction. By performing the fixing at the same time after the image formation by the first and second image forming means using the common conveying means of the annular belt member, the relative image caused by the contraction of the recording material due to the heat at the time of fixing Since the shift can be eliminated, the image shift between the images formed by the first image forming unit and the second image forming unit can be made extremely small. Further, the first image forming unit is an electrophotographic system using a process cartridge, and the second image forming unit is a full-color inkjet system. However, the process speed of the first image forming unit is It is set to be higher than the average process speed of the image forming means. This is because, in the print volume of a general printer user, the ratio of the color original to be printed is often smaller than that of the monochrome image. Therefore, by setting the process speed of the monochrome image forming means to a high speed, the total image formation is performed. The increase in time can be minimized. Further, the image forming means is arranged in the order of first and second from the upstream side, and the image forming order is performed in the order of second and first, so that the interval between the first and second image forming means is recorded. The length can be set smaller than the length in the material conveying direction, and the overall size of the device can be reduced. Further, when forming an image on a short medium such as an envelope or a postcard, there is a paper size detection means (not shown), and it is determined whether or not it is the short medium. If the medium is determined to be the short medium, the first image is detected. It is possible to start image formation from the process cartridge 802, which is the forming unit, and then perform image formation by the inkjet image forming unit 803, which is the second image forming unit. Therefore, the distance between the position where the photosensitive drum 818, which is the image forming position of the process cartridge 802, and the belt 804 are in contact with the head 832, which is the image forming position of the inkjet image forming unit 803, is set to the maximum recording material of the image forming target. The length of the photosensitive drum 818 is set smaller than the length in the carrying direction to realize downsizing of the entire image forming apparatus and the photosensitive drum 818 which is the image forming position of the process cartridge 802.
The distance between the contact position of the belt 804 and the head 832, which is the image forming position of the inkjet image forming unit 803, is set to be larger than the length in the conveying direction of the minimum recording material such as an envelope or a postcard to be image-formed, Images can be formed in order from the process cartridge 802 to the inkjet image forming unit 803.

[0006]

However, when the above-mentioned recording material conveying means using the belt-like conveying member is used,
When the ink ejection nozzles of the inkjet image forming means are arranged with about 64 nozzles aligned in the recording material conveyance direction, the recording material conveyance is intermittent, and every step of intermittent feeding In order to form an image corresponding to a plurality of nozzles, the belt-shaped transport member itself receives an intermittent external force and vibrates, and the recording material and the belt-shaped transport member to be attracted are partly vibrated. And the like, the relative positions of the recording materials are displaced, and as a result, an image formed by the inkjet image forming unit and an image formed by the electrophotographic image forming unit are displaced, and There arises a problem that the quality is remarkably deteriorated.

In view of the above, the present invention solves the above-mentioned problems, and in an image forming apparatus that shares one conveying means composed of a belt-like conveying member and is provided with image forming means according to different image forming methods, One is to provide an image forming apparatus that stably conveys a recording material and eliminates an image shift due to each image forming unit even when the image formation is performed while the recording material is intermittently conveyed. The purpose is to

[0008]

In order to achieve the above-mentioned object, the present invention comprises different image forming means, which means share one conveying means consisting of a belt-like conveying member, and one image of one of the means. In an image forming apparatus in which a recording material is continuously conveyed by the forming means to form an image, and the other image forming means of the means intermittently conveys the recording material to form an image, the recording material is conveyed to the belt-shaped conveying member. A charging unit for electrostatically attracting by a charging action is provided, and the electrostatic attraction by the charging unit is higher in the intermittent transport of the other image forming unit than in the continuous transport of the one image forming unit. This is done at an electric potential. That is, in the image forming apparatus that forms images such as characters or color photographs and halftone dots on the recording material, the first image forming means as one image forming means and the second image forming means as the other image forming means from the upstream side. There is an image forming apparatus in which the image forming unit shares a conveying unit using one belt-shaped and annular conveying member, and the first image forming unit continuously conveys the recording material. Image forming is performed, and the second image forming unit intermittently conveys the recording material to perform the image forming unit, and has a unit for charging the one belt-shaped conveying member.
The recording material electrostatically attracts the recording material to the belt-shaped conveying member to convey the recording material, and when the recording material is conveyed by intermittent feeding, the recording material passes through the image forming portion of the second image forming means. The portion is configured to be electrostatically attracted to the belt-shaped conveying member by the charging means with a higher charging potential than that during continuous feeding. The first image forming unit may be an electrophotographic image forming unit, and the second image forming unit may be an inkjet image forming unit. The charging means for charging the belt-shaped conveying member may also serve as a transfer means for transferring the toner image of the electrophotographic image forming means, which is the first image forming means, onto the recording material. Further, the charging means comprises charge potential changing means for changing the charging potential according to the printing rate for the recording material area, and the printing rate for the recording material area is formed by the second image forming means. Is set based on the image data of the second image forming unit, and the charging potential changing unit sets a certain reference value to the printing rate of the second image forming unit. Is set to a certain high potential, and when it is higher than the reference value, the charging potential is set to a certain low potential, and the charging potential is binary-controlled, or a certain reference value is set, and the reference value is set to On the basis of this, the charging potential may be controlled in multi-valued steps. Further, in the present invention, the belt-shaped conveying member is formed in an endless shape, and a detecting unit for detecting the size of the recording material before electrostatically adsorbing the recording material on the conveying member is provided. When the detection result of the recording material size is a short medium such as an envelope or a postcard, an image is formed by the first image forming unit arranged on the upstream side, and then the second medium arranged on the downstream side. When image formation is performed in the order of the image forming means and it is detected as a recording material other than short media such as a fixed-size cut sheet, the first image forming means does not form an image and first passes the image through When the image is formed by the second image forming means, and then the recording material is kept electrostatically adsorbed, the endless conveying member is made to go around about once, and when it reaches the first image forming means again. The first It may be configured to perform image formation by the image forming means. Further, the belt-shaped conveying member may be provided with a voltage reducing means for gradually reducing the voltage after image formation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is provided with different image forming means as described above, and the means share one conveying means consisting of a belt-like conveying member, and one of the image forming means of the means is a recording material. In the image forming apparatus in which the recording material is continuously conveyed to form an image, and the other image forming means conveys the recording material intermittently to form the image, the recording material is electrostatically charged on the belt-shaped conveying member by a charging action. A charging means for attracting the toner is provided, and the electrostatic attraction by the charging means is performed at a charging potential higher than that of the continuous transportation by the one image forming means in the intermittent transportation by the other image forming means. Since it is configured, it is possible to form an image in a state in which the recording material is surely attracted to the belt-shaped conveying member even in the intermittent feeding by the second image forming unit. Further, by forming the first image forming unit by an electrophotographic image forming unit and the second image forming unit by an inkjet image forming unit, a high-quality color image forming apparatus can be formed in a small size. can do. Further, a simple structure is adopted by also using the charging means for charging the belt-shaped conveying member as the transfer means for transferring the toner image of the electrophotographic image forming means, which is the first image forming means, onto the recording material. You can There are first and second image forming means from upstream in the image forming apparatus for forming images such as characters or color photographs and halftone dots on the recording material, and the image forming means is one belt-like, and In an image forming apparatus that shares a conveying means using an annular conveying member, the first image forming means continuously conveys the recording material to form an image, and the second image forming means intermittently conveys the recording material. The belt-shaped conveying member is electrostatically attracted to the belt-shaped conveying member by the charging action, and the recording material is conveyed by performing the image forming means to electrically charge the belt-shaped conveying member. ,
Means for obtaining the printing rate of the image by the second image forming means with respect to the recording material area from the image data of the image formed by the second image forming means, and the charging potential applied to the belt charging means according to the printing rate. By providing a means for changing the value, the recording material is surely adsorbed to the belt-shaped conveying member even when the printing rate by the second image forming means is low. Further, the charging means comprises charge potential changing means for changing the charging potential according to the printing rate for the recording material area, and the printing rate for the recording material area is formed by the second image forming means. The recording material can be surely adsorbed to the belt-shaped conveying member even when the printing rate by the second image forming unit is low by performing the processing based on the image data. Also,
The charging potential changing means sets one reference value to the printing rate by the second image forming means, and when it is lower than the reference value, the charging potential is a certain high potential or higher than the reference value. In this case, the charging potential is set to a certain low potential, and the charging potential is binary-controlled so that the recording material can be adsorbed at a low printing rate with simple control. Further, the charging potential changing means is configured to set a certain reference value for the printing rate by the second image forming means, and control the charging potential in multiple steps in a stepwise manner based on the reference value. As a result, the recording material can be adsorbed more reliably with a low printing rate.
Further, before electrostatically attracting the recording material to the shared conveying means, a detection means for detecting the size of the recording material is provided, and the detection result of the recording material size by the detection means is
In case of short media such as envelopes and postcards,
When the image formation is performed in the order of the first image forming unit and the second image forming unit and it is detected as a recording material other than short media such as a fixed-size cut sheet, the first image forming unit first temporarily forms an image. The image is formed by the second image forming unit without being formed, and then the shared conveying unit is made to make about one round while keeping the electrostatic attraction of the recording material, and the first image forming unit is again formed. When the image formation is performed by the first image forming unit when it reaches, it is possible to perform image formation by different image forming units even for short media. Further, by providing the belt-shaped conveying member with a voltage reducing unit that gradually reduces the electric charge after image formation, the recording material can be reliably separated from the belt-shaped conveying member.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 shows an overall configuration of an image forming apparatus according to Embodiment 1 of the present invention. The image forming apparatus shown in FIG. 1 has at least two image forming units having different image forming systems, and forms an image on a recording material by these image forming steps. Further, FIG. 2 is a diagram showing the driving force applied to the belt drive roller, which changes with time, in the upper stage, and the adsorption corona applied voltage in the lower stage.
The horizontal axis indicates time T in both lower rows. The configuration and operation will be described with reference to the drawings. It should be noted that description of operations that are the same as those of the conventional image forming apparatus 801 described with reference to FIG. 8 will be omitted. In FIG. 1, 10
Reference numeral 1 denotes an image forming apparatus of the present invention. Specifically, there is a recording material size detection means (not shown) in the manual paper feed port 153, and it is determined whether the manually supplied recording material is a regular cut paper or a short medium such as an envelope or a postcard. Further, the recording material P fed from the feeding cassette 105 is fed to the belt 104.
A pair of registration rollers 113a and 113b, a roller 114, a transport guide, and a roller 116 at a position facing the driven roller 137 on the belt 104 are provided for transporting to a position to be attracted to the upper side. An electrophotographic process cartridge 102 as a first image forming unit is provided downstream thereof, and an inkjet image forming unit 103 as a second image forming unit is provided further downstream thereof to form these two image forming units. As a shared conveying means of the means, it is formed in an annular shape, is supported by a belt driving roller 136 and a belt driven roller 137, and the belt driving roller 136 is rotationally driven in the arrow direction in FIG. Belt drive roller 136
A belt 104 is provided that is driven and driven according to the rotation direction of the. Further, the belt 104 is provided with an adsorption corona 121 that charges the recording material P on the upstream side of the inkjet image forming unit 103 and that adsorbs the recording material P on the belt 104 by electrostatic force. The distance between the process cartridge 102 that is the first image forming unit and the inkjet image forming unit 103 that is the second image forming unit is
It is installed smaller than the maximum length of the recording material to be image-formed in the transport direction to realize the downsizing of the entire device, and the smallest recording material to be image-formed, that is, for short media such as envelopes and postcards. It is installed at intervals larger than the length in the transport direction. Further downstream of the two image forming means, as in the conventional example, a fixing device 139 and a conveyance guide 147 are provided.
a, 147b, a curl removing roller 150, a curl removing roller 150, 151 and the like are provided.

The operation of the first embodiment of the present invention will be described below. When the feeding roller 111 is rotationally driven in the direction of the arrow in FIG. 1, only one recording material P is fed from the cassette 105 by the separating claw 112, and the registration roller pair 11
It is fed to the positions of 3a and 113b. At least the surface of the registration roller 113a contacting the recording material P is made of rubber, and the registration roller 113b is made of metal. The fed recording material P is the registration roller pair 113.
After entering the nip portions of a and 113b, some loops are formed and then stopped. As a result, the skew feeding of the recording material P is corrected. Before and after the above-mentioned operation, electric charges are applied to the adsorption corona 121 by a voltage applying means (not shown), and at the same time, the driving roller 136 drives the belt 104 almost one round to charge the entire area of the belt 104. . Then, the pair of registration rollers 113a and 113b are driven to pass the rollers 114 and the conveyance guide 115 in a state where the skew is corrected, and the belt driven roller 137 and the belt 1 are passed.
By the time the leading edge of the recording material P is conveyed to the position of the roller 116 in the process cartridge 102 installed at the position opposite to the belt 104, the belt 104 at the position of the roller 116 is in a charged state. ing. And roller 1
The recording material P from the position 16 or a position slightly back and forth.
Are electrostatically adsorbed on the belt 104. The recording material P is conveyed by the belt 104 while the electrostatic attraction is maintained, and the photosensitive drum 1 in the process cartridge 102 is conveyed.
It reaches the position where 18 and the belt 104 contact.

The order of image formation is exactly the same as that of the conventional example. In the case of the standard cut paper, the electrophotographic process cartridge 102, which is the first image forming means, passes through and the second image forming means. An image is formed from the inkjet image forming unit 103, and the recording material P is the belt 104.
While keeping the state of being electrostatically attracted to the upper side, the belt 104 is driven to make one round and the image is again formed by the electrophotographic process cartridge 102 which is the first image forming means. Here, during intermittent feeding, when the recording material P is conveyed, there is a problem that the recording material P is peeled or peeled off due to vibration on the belt 104. That is, the vibration of the drive system (not shown) transmitted from the drive roller 136 to the belt 104 has its amplitude increased on the belt, and in the worst case, the recording material P
However, in this embodiment, the inkjet image forming means 1 is used.
Adsorption corona 1 during intermittent feeding during image formation with 03
By increasing the voltage application of 21, the suction force of the belt 104 is increased and the recording material P is prevented from peeling or peeling.

More specifically, when the recording material P is a standard size cut sheet, that is, the image forming order is the ink jet image forming section 103 which is the second image forming means first, and the second is the first image forming means. In the case of the process cartridge 102, the increase in voltage application will be described with reference to FIGS. 1 and 2. Here, in the lower part of FIG.
The absolute value of the voltage applied to the suction corona is plotted on the vertical axis. This is because the suction corona has a suction effect regardless of whether a positive voltage is applied or a negative voltage is applied. The positive or negative of this applied voltage is the transfer condition at the time of image formation of the process cartridge 102. Also depends on. At time A in FIG. 2, when image data is sent to the image forming apparatus 101 from a computer (not shown) or the like, the belt drive roller 136 is driven. At this time, the driving roller 136 is continuously driven, so that the belt 104 is also continuously driven.
An applied voltage is applied to the adsorption corona 121 at the same time as the driving is started, but the applied voltage at this time is in a low state. The start position of the image to be formed by the inkjet image forming unit 103 on the recording material P is point S in FIG.
At time B when 1 is reached, the voltage applied to the suction corona 121 is appropriately increased to strongly suck the portion of the recording material P after the image start position onto the belt 104. Further, the belt 104 is continuously driven so that the image start position is the print head 1 of the inkjet image forming unit 103.
At time C in FIG. 2, which reaches point S2 near 32,
As shown in FIG. 2, the driving roller 136 has intermittent roller driving force, and the driving roller 136 is driven intermittently. At this time point, the portion of the recording material P strongly adsorbed as described above has reached the point S2, so that the recording material P is not scraped or peeled off even when the intermittent feeding is started. The belt 104 is intermittently driven while image formation is being performed by the inkjet image forming unit 103, and then δ from time D in FIG. 2 at which inkjet image formation ends.
The voltage applied to the adsorption corona 121 is lowered earlier by T. This corresponds to the time when the end of the image passes point S1.
At time D, the driving roller 136 is continuously driven at the same time when the inkjet image formation is completed, and the belt 104
And the recording material P is continuously conveyed.

On the other hand, when the recording medium size detecting means (not shown) determines that the short medium has been fed during manual feeding, the image forming order is reversed from the above, and the electronic image of the first image forming means is reversed. Photographic process cartridge 1
The image formation is started from 02, and then the image formation is performed by the full-color inkjet image forming unit 103 which is the second image forming means downstream thereof. In this case,
Process cartridge 102 which is the first image forming means
After the toner image is transferred to the recording material P after the image formation by the recording medium P is completed and the point S1 in FIG.
The applied voltage is increased by 1. The subsequent intermittent driving of the belt 104 and the synchronization of the upper and lower actions of the applied voltage are the same regardless of the order of image formation. After that, the recording material P on which an image is formed by any one of the above, similarly to the conventional example, is separated by the slow charging corona 134 and the separating claw 135 together with the slow charging of the belt 104, and is fixed by the fixing device 139 by the fixing device 139. The toner image transferred on the recording material P by the corona 120 and the ink image formed by the inkjet image forming unit 103 are permanently fixed on the recording material P. After that, the transport guides 147a, 1
The sheet is discharged to the stacker 152 by the curl removing roller 149 and the curl removing rollers 150 and 151 via 47b. As described above, the first embodiment of the present invention is
In an image forming apparatus that includes two image forming units of different image forming systems and conveys a recording material by a belt-shaped conveying member, one of the image forming units forms an image while intermittently conveying the recording material. Even in such a case, an image forming apparatus is provided which stably conveys a recording material and eliminates image shift due to each image forming unit.

[Embodiment 2] FIG. 3 shows the overall configuration of an image forming apparatus according to Embodiment 2 of the present invention. The image forming apparatus shown in FIG.
In the image forming apparatus of the first embodiment, the suction corona that acts to attract the recording material P to the belt and the transfer corona that is the transfer means of the electrophotographic image forming means that is the first image forming means are used in common. is there. The configuration and operation will be described with reference to the drawings. In addition, as described with reference to FIG.
The description of the same operations as those of the image forming apparatus 101 of the conventional example will be omitted. In FIG. 3, 201 indicates the image forming apparatus of the present invention. A feeding cassette 205 on which the recording material P is loaded, a feeding roller 211 that feeds the recording material P to a belt 204 that adsorbs the recording material P, and an electronic device as a first image forming unit downstream thereof. A photographic process cartridge 202 is provided, and an inkjet image forming section 203 as a second image forming means is provided further downstream thereof, and the belt 204 is formed in an annular shape as a shared conveying means for these two image forming means. The belt 204 is driven by the belt driving roller 236 and the belt driven roller 237, and the belt 204 is also driven in the secondary direction by the driving system (not shown) rotationally driving the belt driving roller 236 in the direction of the arrow in FIG. . In addition, the inkjet image forming unit 20 is attached to the belt 204.
3, the belt 204 is charged on the upstream side, and the attracting action of attracting the recording material P onto the belt 204 by electrostatic force, and the toner image developed on the photosensitive drum 218 in the process cartridge 202 are transferred onto the recording material P. A corona 220 having the function of causing the corona is provided.

The operation of the second embodiment of the present invention will be described below. As in the first embodiment, the recording material P fed from the feeding cassette 205 is adsorbed on the belt 204, and the recording material P is conveyed inside the process cartridge 202 while being electrostatically adsorbed. It reaches the position S3 where the photosensitive drum 218 and the belt 204 contact each other.
Here, in the present image forming apparatus 201, in the case of forming an image on a standard size cut sheet, that is, in the image forming order, the inkjet image forming unit 203 which is the second image forming unit is first, and the first image forming unit is used. The operation when a certain process cartridge 202 is installed later will be described. Similar to the conventional example and the first embodiment, the leading edge of the recording material P reaches the point S3, but the process cartridge 202 is further conveyed without forming an image, and the ink jet image forming portion 203 in the recording material P is conveyed. At time B when the start position of the image to be imaged reaches the point S3 in FIG. 3, the voltage applied to the suction corona 220 is appropriately increased, and the portion after the image start position on the recording material P is It is strongly adsorbed on the belt 204. Further, the belt 204 is continuously driven, and at time C when the image start position reaches the point S4 near the print head 232 of the inkjet image forming unit 203, the drive roller 236 is intermittently driven. At this time point, the portion of the recording material P strongly adsorbed as described above has reached the point S4, so that the recording material P is not scraped or peeled off even when the intermittent feeding is started. The belt 204 is intermittently driven while image formation is being performed by the inkjet image forming unit 203, and the voltage applied to the corona 220 is lowered at a time earlier than the time at which inkjet image formation ends thereafter. This time corresponds to the time when the image end portion passes through the point S3. Driving roller 2 at the same time when the inkjet image formation is completed
36 is continuously driven, and the belt 204 and the recording material P are continuously conveyed. After that, the recording material P is conveyed about one round while being adsorbed on the belt 204, and when it returns to S3 which is the transfer position of the process cartridge 202, image formation is performed by the process cartridge 202, and it is continuously driven, Inkjet image forming unit 20
Then, the toner image and the ink image transferred onto the recording material P by the fixing device 239 are permanently fixed to the recording material P by the fixing device 239, and then discharged to the outside of the image forming apparatus 201. As described below, in the second embodiment of the present invention, the functions of suction and transfer are realized by one corona, so that the recording material can be stably conveyed with a simpler configuration, and each image forming unit can perform the operations. (EN) Provided is an image forming apparatus which eliminates image shift and is quiet.

[Embodiment 3] FIG. 4 shows a flow chart of an applied voltage change command to the adsorption corona according to Embodiment 3 of the present invention. Further, FIG. 5 is a diagram for explaining experimental values showing the relationship between the printing rate of the inkjet image forming means and the suction force of the recording material to the belt, and FIG. 6 is the inkjet printing rate and the application of the suction corona in this embodiment. It is a figure which shows the relationship with a voltage. The operation of this embodiment will be described with reference to the drawings.
The image forming apparatus according to the present exemplary embodiment has a basic configuration at all.
Since the printing order and the like are the same, the description of the device configuration will be omitted. The present inventor measured the ideal area of the ink image after forming the ink jet image to the recording material surface area, that is, the relationship between the ink jet print rate and the suction force, and as shown in FIG. 5, the print rate increased. It has been found that the adsorption power tends to increase. Therefore, when the ink jet printing rate is low, the recording material is easily peeled off from the belt, and conversely, when the ink jet printing rate is high, the recording material is adsorbed on the belt with an excessive suction force. Is completed, and it becomes difficult to separate when separating from the belt. This embodiment was invented in view of this point, and when the ink jet printing rate is low, the applied voltage by the suction corona is increased to correct the suction force, and when the ink jet printing rate is high, the applied voltage is lowered. Then, the adsorption force is corrected to be low.

The operation of the third embodiment of the present invention will be described below. In FIG. 4, when image data is sent from a computer (not shown) or the like, the controller inside the image forming apparatus causes the electrophotographic image forming means, which is the first image forming means, and the second image forming means to operate. Image data to be image-formed by a certain inkjet image forming means is divided into each. On the other hand, the image data for the inkjet image forming means is sent to the inkjet printing rate determining means for determining the inkjet printing rate with respect to the surface area of the recording material to be image-formed, and the printing rate is determined, and the adsorption corona applied voltage changing means , A signal is sent to indicate whether the voltage applied to the suction corona should be increased or decreased. Then, according to the signal, the suction corona applied voltage changing means changes the voltage applied to the suction corona. For example, as shown in Fig. 6, the print rate is x%.
When it is lower, the adsorption corona applied voltage is increased, and when it is x% or more, the adsorption corona voltage is decreased. Therefore, even if the inkjet printing rate is low, the recording material is surely electrostatically adsorbed on the belt and stably conveyed. As described above, in Example 3 of the present invention, when the ink jet printing rate is low, the applied voltage by the suction corona is increased to correct the suction force, and when the ink jet printing rate is high, the applied voltage is lowered. (EN) Provided is an image forming apparatus in which a suction force is corrected to be low, so that a recording material can be stably conveyed and an image shift due to each image forming unit can be eliminated.

[Embodiment 4] FIG. 7 is a graph showing the relationship between the ink jet printing rate and the attraction corona applied voltage in Embodiment 4 of the present invention. The operation of this embodiment will be described with reference to the drawings. The basic structure of the image forming apparatus of the present embodiment is the same as that of the first embodiment, and the printing order and the like are also the same, so the description of the apparatus structure is omitted. Also,
In the present embodiment, the relationship of the applied voltage to the suction corona is controlled more finely according to the printing rate in the third embodiment. The operation of the fourth embodiment of the present invention will be described below. The inkjet printing rate was determined in the same manner as in Example 3,
In response to this, a signal is sent to the adsorption corona applied voltage changing means as to what the adsorption corona applied voltage is. Then, according to the signal, the suction corona applied voltage changing means changes the voltage applied to the suction corona. For example, as shown in FIG. 7, the relationship between the print ratio and the applied voltage to the suction corona is finely divided into several to
There are ten or more stages, and the voltage applied to the adsorption corona is changed accordingly, and the recording material is reliably electrostatically adsorbed on the belt even when the inkjet printing rate is low, and stable conveyance is performed. As described above, in the fourth embodiment of the present invention, the voltage applied to the suction corona is finely corrected in accordance with the inkjet printing rate to more reliably and stably convey the recording material and to form each image. Provided is an image forming apparatus that eliminates image shift due to the means.

[0021]

As described above, according to the present invention, in the image forming apparatus having different image forming means as described above, one of the above-mentioned image forming operations is carried out in the intermittent conveyance of the other image forming means by the electrostatic attraction by the charging means. Since the recording material is configured to be charged at a higher charging potential than that of the continuous conveyance by the means, when the recording material is conveyed by the intermittent feeding, the portion of the recording material passing through the image forming portion of the one image forming means is By the charging means, the belt-shaped conveying member is electrostatically attracted to the belt-shaped conveying member by a charging potential higher than that in the continuous feeding, and the recording material is surely attracted to the belt-shaped conveying member even in the intermittent feeding state. It is possible to provide a high-quality image in which the image formed by the image forming unit and the image forming unit on the other side is not displaced. Further, according to the present invention, the first image forming means is constituted by an electrophotographic image forming means, and the second image forming means is constituted by an ink jet type image forming means, whereby a miniaturized image is formed. A high-quality image can be provided by the forming device. Further, in the present invention, the charging means is constituted by charging potential changing means for changing the charging potential according to the printing rate for the recording material area, and the printing rate for the recording material area is determined by the other image forming means. By performing the process based on the image data of the image to be formed, the recording material can be surely attracted to the belt-shaped conveying member even when the printing rate by the second image forming unit is low, and two image formation can be performed. It is possible to provide a high-quality image with no deviation in the image formed by the means. Further, the charging potential changing means, the printing rate by the second image forming means,
One reference value is set, and if it is lower than the reference value, the charging potential is set to a certain high potential, and if it is higher than the reference value, the charging potential is set to a certain low potential, and the charging potential is binary-controlled. By doing so, the recording material can be adsorbed at a low printing rate with simple control, and the cost can be reduced. Further, the charging potential changing means is configured to set a certain reference value for the printing rate by the second image forming means, and control the charging potential in multiple steps in a stepwise manner based on the reference value. As a result, the recording material can be adsorbed more reliably with a low printing rate.
Furthermore, in the present invention, before the electrostatic attraction of the recording material to the shared conveying means, a detection means for detecting the size of the recording material is provided, and the detection result of the recording material size by the detection means is In the case of short media such as envelopes and postcards, image formation was performed in the order of the first image forming means and the second image forming means, and it was detected as a recording material other than short media such as a standard cut sheet. In this case, the first image forming unit first passes the image without forming the image, and the second image forming unit forms the image,
After that, the shared conveying means is circulated about once while keeping the electrostatic attraction of the recording material, and when the first image forming means is reached again, the first image forming means forms an image. An image can be formed on different types of short media by different image forming means, and a high-quality image can be provided on a short medium. Further, by providing the belt-shaped conveying member with a voltage reducing unit that gradually reduces the electric charge after image formation, the recording material is reliably separated from the belt-shaped conveying member,
It is possible to provide an image forming apparatus that does not cause conveyance failure before a fixing device or the like.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an entire image forming apparatus according to a first exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a voltage applied to the adsorption corona according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an entire image forming apparatus according to a second exemplary embodiment of the present invention.

FIG. 4 is a flow chart of a command for changing an applied voltage to an adsorption corona according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between an inkjet printing rate and a suction force of a recording material onto a belt.

FIG. 6 is a diagram illustrating a relationship between an inkjet printing rate and an applied voltage attraction force to an attraction corona according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between an inkjet printing rate and an applied voltage attraction force to an attraction corona according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a conventional image forming apparatus.

[Description of sign]

 101, 201, 801 Image forming apparatus 102, 202, 802 Process cartridge 103, 203, 803 Inkjet image forming unit 104, 204, 804 Belt 105, 205, 805 Feed cassette 111, 211, 811 Feed roller 118, 218, 818 Photosensitive drum 120, 820 Transfer corona 121, 821 Adsorption corona 129, 229, 829 Carriage 132, 232, 832 Print head 136, 236, 836 Drive roller 137, 237, 837 Follower roller 139, 239, 839 Fixer 220 Corona P Recording material

Claims (9)

[Claims] 1. A different image forming means is provided, which means shares one conveying means comprising a belt-like conveying member, and one of the image forming means of the means continuously conveys a recording material to form an image. In the other image forming means of the means, in an image forming apparatus for intermittently conveying a recording material to form an image, a charging means for electrostatically adsorbing the recording material to the belt-shaped conveying member by a charging action, An image forming apparatus, wherein electrostatic attraction by the charging means is performed at a charging potential higher than that of continuous conveyance by the one image forming means in intermittent conveyance by the other image forming means. 2. The image forming apparatus according to claim 1, wherein the one image forming unit is an electrophotographic image forming unit and the other image forming unit is an inkjet image forming unit. . 3. The charging device also functions as a transfer device for transferring a toner image of the electrophotographic image forming device, which is the one image forming device, to a recording material. 2. The image forming apparatus according to item 2. 4. The charging means is constituted by a charging potential changing means for changing the charging potential according to the printing ratio with respect to the area of the recording material. The image forming apparatus according to item. 5. The charging potential changing means is configured so that the printing rate for the recording material area is based on image data of an image formed by the other image forming means. Image forming apparatus. 6. The charging potential changing means sets one reference value for the printing rate, and when it is lower than the reference value, sets the charging potential to a certain high potential and is higher than the reference value. In some cases, the charging potential is set to a certain low potential, and the charging potential is binary-controlled, and the image forming apparatus according to claim 4 or 5. 7. The charging potential changing means sets some reference values for the printing rate, and controls the charging potential in multiple steps in a stepwise manner based on the reference values. The image forming apparatus according to claim 4 or claim 5. 8. The belt-shaped conveying member is formed in an endless shape, and has a detecting means for detecting the size of the recording material before electrostatically adsorbing the recording material on the conveying member, and the recording material by the detecting means. If the size detection result is a short medium such as an envelope or a postcard, image formation is performed by the one image forming unit arranged upstream, and then the other image forming unit of the other image forming unit arranged downstream is formed. When image formation is performed in order and it is detected as a recording material other than short media, such as a standard cut sheet, the image formation is not performed by the one image formation means, and the image formation means is first passed through the other image formation means. Image formation is performed by the above-mentioned method, and thereafter, the endless conveying member is made to make one round while keeping the electrostatic attraction of the recording material, and when the one image forming means is reached again, the one image forming means is formed. The image forming apparatus according to any one of claims 1 to 7, wherein the image is formed by the following method. 9. A gradual charging means for gradually charging the belt-shaped conveying member after image formation is provided.
The image forming apparatus according to claim 8.