JP5532967B2 - Image deviation correction apparatus, image forming apparatus, and image forming system for toner image - Google Patents

Description

  The present invention relates to a toner image misregistration correction apparatus that corrects image misregistration of toner images of both image forming apparatuses when the electrophotographic image forming apparatuses are connected to each other, and an image forming apparatus including the correction apparatus. The present invention relates to an image forming system.

  In general, toner used in an electrophotographic image forming apparatus has only one black color for a monochrome image and four basic colors of black, magenta, cyan, and yellow for a full-color image. There are special toners such as a toner that gives glossiness to an image, a toner that gives a three-dimensional effect, a metal color (gold, silver, etc.) toner, and a white toner.

Regarding glossiness, for example, gloss is imparted by additionally transferring and fixing a toner image of a transparent toner on a sheet material on which a color image is formed (see, for example, Patent Document 1).
Regarding the three-dimensional effect, for example, by using a toner containing a foaming agent, it is possible to form an image having a three-dimensional effect such as Braille (see, for example, Patent Document 2).
Regarding the metal color, for example, a metal color image can be formed by adding a metal color developing device in addition to the conventional four colors described above (see, for example, Patent Document 3).

  If a fifth developing device is added as in Patent Document 3 in order to use these special toners together, the image forming apparatus becomes large. However, this is an unnecessary function and undesirable for users who do not need to use these special toners in combination.

  In view of this, a special toner image forming apparatus (second apparatus) is made independent of the basic four-color image forming apparatus (first apparatus) and is detachable as an option (for example, Patent Document 4, (See Patent Document 5 and Patent Document 6).

Patent Document 6 discloses a device in which a second device that imparts gloss with a transparent dry toner is connected downstream of a first device that forms a colored image by wet development.
Patent Document 4, Patent Document 5, and Patent Document 6 disclose a configuration in which a second device that gives a three-dimensional effect or the like with a special toner such as an expandable toner can be incorporated under or next to the first device as an option. ing.

  As described above, when the special toner image forming apparatus is made independent, there is a problem that the image position on the sheet material such as transfer paper or transfer film is shifted between the first apparatus and the second apparatus. However, when glossiness is imparted with a transparent toner, the transparent toner is often uniformly adhered to the entire surface of the sheet material, and the image shift of the special toner as described above has not been a problem. In particular, it is expected that more advanced demands such as giving a glossy feeling and a three-dimensional feeling will increase, and it is possible to accurately align the image of the four basic colors (first device) and the image of the special toner (second device). It becomes important.

  On the other hand, even in a single image forming apparatus using basic four color toners, there is a problem that the position of forming an image for each color is shifted. As a countermeasure, color misregistration correction is widely performed. For example, an image pattern for position detection is formed on the intermediate transfer belt, and an image shift amount of the toner image is detected based on the detection result to perform color shift correction (see, for example, Patent Document 7). Further, in a configuration having a conveyor belt, a similar image pattern is formed on the conveyor belt to detect an image shift amount and to perform color shift correction in many cases.

However, in an arrangement in which the image forming apparatus (second apparatus) using special toner is made independent from the image forming apparatus (first apparatus) using basic four color toners and is detachable as an option, an intermediate transfer belt or a conveyance belt is used. Therefore, the image shift amount cannot be detected and the image shift correction cannot be performed using the technique of Patent Document 7. In addition, it is necessary to reliably detect images of various special toners including transparent toners.
Accordingly, the present invention has been made in view of such a situation, and an object thereof is to provide a toner image misregistration correction apparatus, an image forming apparatus, and an image forming system capable of solving the above problems.

In order to solve the above-described problems, a toner image image shift correction device, an image forming apparatus, and an image forming system according to the present invention employ the following technical means.
According to a first aspect of the present invention, there is provided a first toner image formed by the first image forming apparatus and a second toner formed by the second image forming apparatus provided in the first image forming apparatus. An image misalignment correction apparatus for a toner image that corrects image misalignment of a toner image composed of an image, wherein the toner of the second toner image is white when unfixed and becomes transparent after fixing, or undecided The second image forming apparatus is provided with a toner that is white at the time of wearing and after fixing. The second image forming apparatus is provided in a conveyance path in which the sheet material is conveyed and in the middle of the conveyance path, and the first toner image is fixed. And a transfer unit that transfers the second toner image to the sheet material. The transfer unit is provided upstream of the transfer unit with the transfer unit as a base point, and detects the first toner image of the sheet material being transferred. The detection part and the transfer part And a transfer target to which the second toner image being transferred transferred to the sheet material by the transfer unit is transferred, and the second toner image transferred to the transfer target is detected. An image shift amount between the first toner image and the second toner image using the second detection unit that performs detection, the detection information of the first detection unit, and the detection information of the second detection unit And the operation of the second image forming apparatus can be controlled or the operations of both the first image forming apparatus and the second image forming apparatus can be corrected. An image shift correction device for a toner image including an image shift correction control unit to be controlled is characterized.
According to a second aspect of the present invention, in the first aspect, a fixing body for fixing the toner image transferred to the sheet material by the transfer unit on the sheet material is provided on the downstream side of conveyance with the transfer unit as a base point, The transfer target is provided between the transfer portion and the fixing member.
According to a third aspect of the present invention, in the first aspect, a fixing body for fixing the toner image transferred to the sheet material by the transfer unit to the sheet material is provided on the downstream side of conveyance with the transfer unit as a base point, The transfer target is also used as the fixing member, and is configured to be able to transfer the second toner image transferred to the sheet material to the fixing member and to control the fixing temperature of the fixing member. It is characterized by.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the cleaning unit is provided so as to be in contact with the transferred body and capable of removing the second toner image from the transferred body. It is characterized by that.
A fifth aspect of the present invention is the cartridge according to the fourth aspect, wherein the cleaning unit and the transfer target are supported by a common case, and the cartridge is detachable from the second image forming apparatus. It is characterized by that.
According to a sixth aspect of the present invention, in the method according to any one of the first to fifth aspects, the second transfer unit moves the second portion within a range corresponding to a circumferential length of the transfer target body from the front end of the sheet material. The toner image is configured to be transferable to the sheet material.
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the first detection unit and the second detection unit include a reflective optical sensor.
According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the image misalignment correction control unit is configured to turn on or wait for the main power of the first image forming apparatus and the second image forming apparatus. When an image formation request is made when the temperature of the fixing body is lower than the temperature at which the fixing body can be fixed, such as when shifting to a mode, the image misalignment correction operation is executed before the fixing body reaches a temperature at which the fixing body can be fixed. It is configured to be possible .
According to a ninth aspect of the present invention, there is provided an image forming apparatus including the toner image misregistration correcting apparatus according to any one of the first to eighth aspects.
According to a tenth aspect of the present invention, the toner image misregistration correction device according to any one of the first to seventh aspects , the first image forming device, and the second image forming device are provided. The image forming system is configured such that the first image forming apparatus and the second image forming apparatus can independently form images even when they are not provided .

  According to the present invention, it is possible to detect an image shift amount and perform image shift correction even if a transport system such as an intermediate transfer belt or a transport belt does not straddle between apparatuses. In addition, it is possible to reliably detect images of various special toners including transparent toners.

1 is a schematic longitudinal sectional front view showing a configuration of an image forming system according to a first embodiment; FIG. 6 is an image diagram when the first toner image and the second toner image are misaligned. FIG. 4 is a schematic longitudinal sectional front view showing a configuration of a second image forming apparatus according to a second embodiment. FIG. 6 is an image diagram illustrating a positional relationship of a second toner image on a sheet material. FIG. 5 is a diagram illustrating a relationship between a fixing nip temperature and time when a sheet material passes through a fixing nip. FIG. 4 is an image diagram when a first toner image and a second toner image composed of respective colors are misaligned.

An embodiment of an image forming system according to the present invention will be described with reference to the accompanying drawings.
(Embodiment 1)
The image forming system according to the first embodiment includes an upstream first image forming apparatus 1 that uses toner of four basic colors of black, magenta, cyan, and yellow, and an image shift of a toner image that is a main part of the present invention. It is comprised with the 2nd image forming apparatus 2 of the downstream provided with the correction | amendment apparatus 3. FIG. The first image forming apparatus 1 and the second image forming apparatus 2 are provided so as to be able to deliver a sheet material. The first image forming apparatus 1 and the second image forming apparatus 2 can independently form images even when they are not provided.

  As shown in FIG. 1, the first image forming apparatus 1 includes an image forming unit, a writing unit 105, an intermediate transfer unit, a transfer conveyance unit, a fixing unit, and a paper feeding unit.

The image forming unit includes a photosensitive drum 101 rotatably provided in a counterclockwise direction, and a structure disposed around the photosensitive drum 101. In this structure, the vicinity of the lowermost portion of the outer peripheral surface of the photosensitive drum 101 is a transfer position for transferring a toner image on the photosensitive drum 101 to an intermediate transfer belt 109 (described later), and the counterclockwise direction is based on the transfer position. In order, the cleaning device 102 for removing unnecessary toner, carrier, paper dust and other unnecessary materials on the peripheral surface of the photosensitive drum 101, and a rotatable space so as to form a required gap from the peripheral surface of the photosensitive drum 101 are provided. A charging roller 103 for charging the circumferential surface of the photosensitive drum 101 uniformly by applying a charging bias obtained by superimposing an AC voltage on a DC voltage from a charging bias applying means (not shown), and a two-component developer composed of polymerized toner and a carrier. A developing unit 104 is provided that develops the electrostatic latent image that has been transported and formed on the peripheral surface of the photosensitive drum 101 into a toner image.
Four image forming units are provided at predetermined intervals in the horizontal direction. In FIG. 1, from left to right, yellow toner image, magenta toner image, cyan toner image, black This is an image forming unit for toner images. In FIG. 1, in the photosensitive drum 101, the yellow toner image forming unit is Y, the magenta toner image forming unit is M, the cyan toner image forming unit is C, and the black toner image forming unit is B. Show.

  The writing unit 105 is provided above the image forming unit, and scan light in the main scanning direction is applied to the rotating photosensitive drum 101 through an opening formed between the charging roller 103 and the developing device 104. Irradiation is performed to form an electrostatic latent image based on the image data.

  The intermediate transfer unit is rotatable in a clockwise direction that is stretched along the image forming unit on a roller portion in which a driving roller 106, a driven roller 107, and a secondary transfer counter roller 108 are arranged in a substantially inverted triangular shape. An intermediate transfer belt 109, a primary transfer roller 110 provided to face each photosensitive drum 101 across the intermediate transfer belt 109, and transfers a toner image formed on each photosensitive drum 101 to the intermediate transfer belt 109; A cleaning device 111 is provided between the secondary transfer opposing roller 108 and the driven roller 107 to remove unnecessary materials such as residual toner, carrier, and paper dust on the intermediate transfer belt 109.

  The transfer conveyance unit is stretched between a driving roller 112 provided on the left side and a driven roller 113 provided on the right side with the secondary transfer counter roller 108 as a substantial center in the left-right direction, and a counterclockwise clock that conveys the sheet material. The first transfer belt 114 that can rotate around, and the toner transferred to the intermediate transfer belt 109 provided to face the secondary transfer counter roller 108 with the first transfer belt 114 and the intermediate transfer belt 109 interposed therebetween. A secondary transfer roller 115 for transferring an image onto a sheet material on the first conveying belt 114, a registration roller 116 for feeding the sheet material to the first conveying belt 114 at a predetermined timing, and a sheet from a sheet feeding unit described later. Is conveyed toward the registration roller 116, and a sheet on which a toner image is fixed by a fixing unit to be described later is passed through a discharge port 118. And a plurality of conveying rollers 117 to be discharged to 置外.

  Among these, the first conveyor belt 114 is an endless belt having a volume resistivity of 1010 to 1015 Ω · cm and a surface resistivity of 1010 to 1015 Ω / □. For example, the first conveyor belt 114 is a modified polyimide, thermosetting polyimide, polycarbonate, ethylene tetrafluoroethylene, or the like. On the outside of a semiconductive film substrate having a thickness of 0.1 to 1.0 mm in which a conductive material is dispersed in an engineering plastic such as a polymer, polyvinylidene fluoride, and nylon alloy, the toner filming prevention layer has a thickness of 5 to 50 μm. A seamless belt having a two-layer structure subjected to fluorine coating may be mentioned. In addition to this, a semiconductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber, urethane rubber, or the like can also be used as the base of the transfer belt.

  As the secondary transfer roller 115, a volume resistivity of 1 × 10 5 Ω · cm to 1 × 10 12 Ω · cm, a thickness of 2 mm to 10 mm, and a rubber hardness of 10 ° to 100 ° are disposed around a metal roller or a metal core. And those coated with a conductive elastic layer. The elastic layer may be foamable.

  The fixing unit includes a fixing roller 119 provided with a heating source therein, and a pressure roller 120 that is rotatably fitted along the longitudinal direction of the fixing roller 119, and is conveyed by the first conveying belt 114. By accepting the material and applying heat and pressure to the sheet material, the unfixed basic color toner image is melted and solidified and fixed on the sheet material.

  The sheet feeding unit is disposed below the first image forming apparatus 1 and includes a sheet feeding tray 121 in which the sheet material S is accommodated, and a sheet feeding unit that takes out the sheet material S accommodated in the sheet feeding tray 121 one by one. A paper roller 122.

A series of operations of the first image forming apparatus 1 configured as described above will be described.
The photosensitive drum 101 is rotated counterclockwise in the drawing by a driving unit (not shown), and the peripheral surface of the photosensitive drum 101 is uniformly charged to a predetermined polarity by the charging roller 103. Scanning light is irradiated from the writing unit 105 toward the charged surface of the photosensitive drum 101, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 101. At this time, the image information exposed on each photosensitive drum 101 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The developing device 104 visualizes the electrostatic latent image as a toner image.

  Further, the intermediate transfer belt 109 rotates clockwise in the figure, and the respective color toner images are sequentially transferred from the photosensitive drum 101 to the intermediate transfer belt 109 by the action of the primary transfer roller 110 in each image forming unit. In this way, a full color toner image is formed on the surface of the intermediate transfer belt 109. A single color image is formed using any one of the image forming units, or a two-color or three-color image is formed using any two or three of the plurality of image forming units. It is also possible to do. In the case of monochrome printing, image formation is performed using the black image forming unit on the rightmost side of the figure among the four image forming units.

  Before and after the above operation, the sheet feeding roller 122 starts conveying the sheet material made of white transfer paper from the sheet feeding tray 121. The sheet material that has started to be conveyed is sent out toward the secondary transfer position by the registration roller 116 in accordance with the movement of the toner image carried on the intermediate transfer belt 109, and the surface of the intermediate transfer belt 109 by the secondary transfer roller 115. The toner image is transferred. The sheet material carrying the toner image is sent to the fixing unit, and the toner image is fused and fixed to the sheet material by heat and pressure, and sent to the second image forming apparatus 2 through the discharge port 118.

  In the first image forming apparatus 1, the density adjustment of the basic four color toner images of black, magenta, cyan, and yellow and the alignment of the toner images of the respective colors can be performed on the intermediate transfer belt 109. A known misalignment correction unit is provided. By performing this adjustment as appropriate, the second image forming apparatus 2 is fed with a sheet material on which the toner image is fixed and has an appropriate density and no image shift.

As shown in FIG. 1, the second image forming apparatus 2 includes an image forming unit, a writing unit 205, a transfer conveyance unit, a fixing unit, and a toner image image deviation correction device 3. The sheet material discharged through the discharge port 118 of the image forming apparatus 1 is detachably connected to the first image forming apparatus 1 so as to be received through the receiving port 212. The second image forming apparatus 2 and the first image forming apparatus 1 are separated from each other so that each can independently perform an image forming operation.
The toner used in the second image forming apparatus 2 is a toner that is white when unfixed and becomes transparent after fixing, a toner that is white when unfixed and after fixing, or a toner that gives a three-dimensional effect. And special toners such as metal color (gold, silver, etc.) toners.

The first image forming apparatus 1 described above except that the image forming unit is rotated in the reverse direction with respect to the photosensitive drum 201 and the arrangement of the cleaning device 202, the charging roller 203, and the developing device 204 is reversed. The image forming unit has substantially the same configuration. The special toner image image forming unit is denoted by CL.

  The writing unit 205 is substantially the same as the writing unit 105 of the first image forming apparatus 1 described above, and is in the main scanning direction through an opening formed between the charging roller 203 and the developing device 204. Is applied to the rotating photosensitive drum 201 to form an electrostatic latent image based on the image data.

  The transfer conveyance unit can be rotated counterclockwise around the photosensitive drum 201 around a photosensitive roller 201 and a drive roller 206 provided on the left side and a driven roller 207 provided on the right side to convey the sheet material. A second conveyance belt 208 and a toner image formed on the photosensitive drum 201 provided to face the photosensitive drum 201 with the second conveyance belt 208 interposed therebetween. A transfer roller 209 for forming a transfer nip N (transfer portion) to be transferred, a registration roller 210 for feeding a sheet material to the second conveying belt 208 at a predetermined timing, and a sheet on which a toner image is fixed by a fixing unit described later. And a special roller image, such as transparent or white, formed on the photosensitive drum 201, with a conveying roller 211 that is discharged outside the apparatus through the discharge port. , The sheet material on the second conveyor belt 208 (the first image forming apparatus 1 in the sheet material in which the first toner image is fixed) is adapted to transfer directly. Of these, the configurations of the second conveyance belt 208 and the transfer roller 209 are substantially the same as those of the first conveyance belt 114 and the secondary transfer roller 115 of the first image forming apparatus 1 described above.

  The fixing unit includes a fixing roller 213 as a fixing body having a heating source therein, and a pressure roller 214 that is rotatably arranged along the longitudinal direction of the fixing roller 213. By accepting the conveyed sheet material and applying heat and pressure to the sheet material, the unfixed special toner image is melted and solidified and fixed on the sheet material.

  As shown in FIG. 1, the toner image misregistration correction apparatus 3 includes a first detection unit 301, a transfer target unit, a second detection unit 306, a cleaning unit 309, and an image misregistration correction control unit. Prepare.

  The first detection unit 301 is provided upstream of the transfer roller 209 and upstream of the registration roller 210 and downstream of the registration roller 210 such that the detection surface faces the conveyance path 215 through which the sheet material is conveyed. And a reflection type optical sensor including a light receiving element 303 for detecting diffuse reflection light, and detects the first toner image being conveyed fixed on the sheet material.

That is, the portion of the toner image fixed on the sheet material has a higher glossiness than the portion that is off the toner image. Therefore, when there is a toner image, the diffuse reflection light is weaker and the regular reflection light becomes stronger than when there is no toner image. By reading the change, the position of the toner image on the sheet material can be known. In the present embodiment, the configuration for detecting the diffusely reflected light is shown. However, the configuration for detecting the regularly reflected light by using the regular reflected light receiving element may be used.
Examples of the light emitting element 302 include an LED and a GaAs light emitting diode having a peak emission wavelength of 950 nm. Examples of the light receiving element 303 include a Si phototransistor having a peak spectral sensitivity wavelength of 800 nm and a PD (photodiode).

  Further, as shown in FIG. 4, the first toner image P1 has, for example, straight lines and diagonal lines alternately formed at predetermined intervals in the sub-scanning direction (conveying direction), and the figure is formed in the main scanning direction ( This is a test toner image formed at the center and both ends in the sheet material width direction. Note that the toner image shown in FIG. 4 represents the second toner image P2. In FIG. 2, the straight and oblique lines shown as black belts indicate the first toner image (fixed) P1, and the straight and diagonal lines shown as white belts indicate the second toner image (unfixed) P2. ing.

  The transferred portion is a columnar shape that is rotatably provided with a predetermined gap from the surface of the second conveyance belt 208 in the span of the second conveyance belt 208 on the downstream side of the conveyance with the transfer roller 209 as a base point. And a retransfer roller facing roller 305 rotatably provided so as to face the retransfer roller 304 with the second conveying belt 208 interposed therebetween, and is transferred to the sheet material. The transferred second toner image (white or transparent test pattern toner image) is configured to be transferred so as to be wound up by the retransfer roller 304. For example, the re-transfer roller 304 may be composed of a modified polyimide having a volume resistivity of 1010 to 1015 Ω · cm, a thermosetting polyimide, a polycarbonate, and an ethylenetetrafluoroethylene in which a resistance is adjusted by carbon dispersion on a core metal having a diameter of 30 mm. Examples include non-white ones in which engineering plastics such as polymers, polyvinylidene fluoride, and nylon alloys are coated with a thickness of 50 to 200 μm.

  The second detection unit 306 includes a reflection-type optical sensor provided with a light-emitting element 307 and a light-receiving element 308 that detects diffuse reflection light. The re-transfer roller 304 is provided so that the detection surface faces the re-transfer roller 304. The rotating second toner image transferred to the toner image is detected. The reflective optical sensor of the second detection unit 306 is the same as the reflective optical sensor of the first detection unit 301. Further, like the first detection unit 301, the second detection unit 306 may be configured to detect regular reflection light using a regular reflection light receiving element.

  The cleaning unit 309 is provided on the downstream side of the second detection unit 306 in the vicinity of the second detection unit 306 so as to be in contact with the re-transfer roller 304, and the re-detection detected by the second detection unit 306. A blade that scrapes off the second toner image on the transfer roller 304 is provided, and the toner scraped off by the blade can be conveyed to a collection bottle (not shown). The cleaning unit 309 is supported by a common case with the retransfer roller 304 and is configured as a cartridge that can be attached to and detached from the main body of the second image forming apparatus 2. In this embodiment, the second toner image is scraped off with a blade, but a fur brush roller or a magnetic brush cleaning system may be used.

  The image shift correction control unit uses the detection information of the first detection unit 301 and the detection information of the second detection unit 306 to cause image shift between the first toner image and the second toner image in the transfer nip N. The amount of the image is detected, and the operation of the main body of the second image forming apparatus 2 is controlled so that the image shift can be corrected from the image shift amount. This image misalignment correction operation is appropriately executed every time a predetermined number of images are formed by the second image forming apparatus 2 when the main power supply of the main body of the second image forming apparatus 2 is turned on, when shifting to the standby mode. It has become. Details of the image shift correction operation by the image shift correction control unit will be described later.

A series of image forming operations of the second image forming apparatus 2 configured as described above will be described.
The photosensitive drum 201 is rotated in the clockwise direction in the drawing by a driving unit (not shown), and the peripheral surface of the photosensitive drum 201 is uniformly charged to a predetermined polarity by the charging roller 203. Scanning light is irradiated from the writing unit 205 toward the charged surface of the photosensitive drum 201, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 201. At this time, the image information exposed to the photosensitive drum 201 is image information of a desired image to be superimposed on the toner image formed by the first image forming apparatus 1. The developing device 204 develops the electrostatic latent image using special toner.

Before and after the above operation, the sheet material on which the basic color toner image discharged from the first image forming apparatus 1 is fixed is received, and the movement of the sheet material is temporarily stopped and waited by the registration roller 210.
The sheet material is sent to the second conveying belt 208 toward the fixing nip N by the registration roller 210 in accordance with the movement of the toner image carried on the photosensitive drum 201, and the toner on the photosensitive drum 201 is transferred by the transfer roller 209. The image is transferred. The sheet material carrying the toner image is sent to a fixing unit, and a special toner image (for example, transparent or white) is melted and fixed on the sheet material by heat and pressure, and is discharged to the outside of the second image forming apparatus 2 through the discharge port. Discharged.

  Next, a series of operations for correcting the image shift of the toner image by the image shift correction device 3 for the toner image will be described. The registration of the toner images of the respective colors in the first image forming apparatus 1 is already completed, and the second image forming apparatus 2 has the first toner image (straight line and It is assumed that a sheet material on which a diagonal line and a graphic alternating in the sub-scanning direction (conveying direction) are fixed is sent by a control command on the second image forming apparatus 2 side.

  First, the photosensitive drum 201 is rotated in the clockwise direction in the drawing by a driving unit (not shown), and the peripheral surface of the photosensitive drum 201 is uniformly charged to a predetermined polarity by the charging roller 203. Scanning light is irradiated from the writing unit 205 toward the charged surface of the photosensitive drum 201, thereby forming an electrostatic latent image for forming a second toner image on the surface of the photosensitive drum 201. The developing device 204 develops the electrostatic latent image using special toner.

Before and after the above operation, the sheet material on which the first toner image discharged from the first image forming apparatus 1 is fixed is received, and the movement of the sheet material is temporarily stopped and waited by the registration roller 210.
The sheet material is sent to the second conveying belt 208 toward the fixing nip N by the registration roller 210 in accordance with the movement of the toner image carried on the photosensitive drum 201. At this time, the first detection unit 301 detects the first toner image fixed on the sheet material being conveyed. That is, as shown in the figure, after the first straight line in the conveyance direction is detected, the constant conveyance speed and the interval X2 between the diagonal line and the straight line with no image displacement with respect to the first detection unit 301 are constant. It is detected at every time interval.

  Then, the second toner image on the photosensitive drum 201 is transferred to the sheet material by the transfer roller 209, and is moved toward the rotating retransfer roller 304 by the second conveyance belt 208. The second toner image on the sheet material is transferred to the peripheral surface of the retransfer roller 304 so as to be wound up. At this time, the second detection unit 306 detects the second toner image transferred to the rotating retransfer roller 304. The amount of deviation of the second toner image in the sub-scanning direction with respect to the first toner image is detected from the detection time of the second toner image starting from when the first toner image is detected by the first detection unit 301. . On the other hand, the detection interval is detected starting from detection of the first straight line of the second toner image, and the amount of deviation of the second toner image in the main scanning direction is detected.

As shown in FIG. 2, the position interval of the second toner image at the detection position (on the center line in FIG. 2) of the second detection unit 306 due to the image shift of the second toner image P2 in the main scanning direction. Changes to X3 and X4. Detection by the second detection unit 306 under a constant conveyance speed results in a detection interval, and the amount of image shift in the main scanning direction of the second toner image P2 can be grasped.
On the other hand, when the second toner image P2 shifts in the sub-scanning direction with respect to the first toner image P1, the detection time for the interval of X1 shifts on the condition of a constant transport speed, and the detection time is reached. Accordingly, the amount of image shift in the sub-scanning direction of the second toner image P2 can be grasped.

Then, the writing timing of the writing unit 205 is corrected so as to cancel the detected image shift amount in the main scanning direction and the image shift amount in the sub-scanning direction. In particular, the correction of the image shift amount in the sub-scanning direction may correct the sheet material feeding timing by the registration roller 210.
The correction operation of the second toner image with respect to the first toner image is performed when the main power supply of the main body of the second image forming apparatus 2 is turned on, or when the standby mode is entered, the number of images formed by the second image forming apparatus 2 The process is appropriately executed every predetermined number of sheets. Further, the correction operation using the first toner image by the first image forming apparatus 1 and the pace may be executed in synchronization.

  As described above, the image forming system according to the first embodiment can detect an image shift amount and perform image shift correction even if a transport system such as an intermediate transfer belt or a transport belt does not straddle between apparatuses. In addition, the second toner image is transferred to the retransfer roller 304 and then detected by the second detection unit 306 so that the toner that is unfixed is white and becomes transparent after fixing, or the toner that is not fixed and fixed. Even if a special toner that cannot be detected on a white transfer paper (sheet material) such as a toner that is white later is used, it can be reliably detected.

(Embodiment 2)
The second embodiment shows another aspect of the image misregistration correction apparatus for a toner image, which is a main part of the present invention. Since the configuration other than the main part is the same as that of the first embodiment, detailed description is omitted. To do.
As shown in FIG. 3, the toner image misregistration correction apparatus 3 according to the second embodiment uses a fixing roller 310 (non-white) as a fixing body instead of the retransfer roller 304, and re-transfers the toner image. In place of the transfer roller facing roller 305, a fixing temperature control unit is provided. A cleaning roller 311 (or a cleaning brush) for removing the second toner image transferred to the fixing roller 310 is provided, and the second detection unit 306 is used as the fixing roller. The other configuration is the same as that of the toner image misregistration correction apparatus 3 according to the first embodiment.

  When the optimum fixing temperature of the above-mentioned special toner is, for example, 155 degrees Celsius, the above-described special toner is not melt-fixed on the sheet material by adjusting the temperature within a range of 120 degrees Celsius to 130 degrees Celsius. Then, the image is transferred to the fixing roller 310. The fixing temperature control unit described above performs a constant temperature maintenance control capable of fixing and a constant temperature maintenance control capable of transfer. The temperature is not limited to the above range depending on the material of the fixing roller 310, the heat capacity of the fixing unit, the melting point of the toner, the fixing nip time, and the thickness of the transfer paper to be passed.

In particular, in the case where the fixing roller 310 is a transfer target, as shown in FIG. 4, the second nip N causes the second nip N to fall within a range corresponding to the circumferential length of the fixing roller 310 from the leading edge of the sheet material. The toner image is transferred to the sheet material. That is, the length of the second toner image in the sub-scanning direction is within the range corresponding to the circumferential length of the fixing roller 310 from the leading edge of the sheet material.
FIG. 5 shows a change with time of the temperature of the fixing nip. The paper passing time is from the time indicated by the arrow indicated as the leading edge of the sheet material in FIG. 5 to the time indicated by the arrow indicated as the trailing edge of the sheet material. Further, the time range indicated as one rotation of the fixing roller 310 in the drawing is the time for the circumferential distance of the fixing roller 310 to pass through the nip with the transfer paper.

As apparent from FIG. 5, after the sheet paper has passed through one rotation of the fixing roller 310 (second rotation of the fixing roller 310), the heat of the fixing roller 310 is taken away by the sheet material. The nip temperature is low.
Therefore, in the time after the second round of the fixing roller 310, the fixing temperature is below the lower limit temperature (120 ° C.) at which transfer is possible, and the second toner image on the sheet material is not fixed or transferred. Will be output as is.

  Therefore, the position where the second toner image is formed is created at a distance from the sheet material to at least one round of the fixing member represented by the fixing roller 310 or the fixing belt, so that the second toner image is formed at the target temperature. All of the toner images can be transferred from the sheet material to the fixing member.

  A series of image misalignment correction operations performed by the toner image image misalignment correction apparatus 3 according to the second embodiment configured as described above are the same as those in the first embodiment, and are omitted. When the temperature of the fixing body is lower than the fixing temperature, such as when the main power of both the first image forming apparatus 1 and the second image forming apparatus 2 is turned on or when the mode is changed to the standby mode, In such a case, it is preferable from the viewpoint of energy saving to execute an image shift correction operation before reaching a predetermined fixing temperature.

  Further, in the present embodiment, the alignment of the toner images of the respective colors in the first image forming apparatus 1 has already been completed, and the second image forming apparatus 2 has the first density with an appropriate density and no image shift. Sheet material on which a toner image (a graphic in which straight lines and diagonal lines are alternately arranged in the sub-scanning direction (conveyance direction)) is fixed is sent by a control command on the second image forming apparatus 2 side. An example of detecting the positional deviation of the second toner image with reference to the first toner image and correcting the operation of the second image forming apparatus based on the detection result is shown. Each color by the first image forming apparatus is exemplified. The toner image may be aligned with the second toner image at the same time.

  That is, each image forming unit of the first image forming apparatus forms a black toner image, a cyan toner image, and a magenta toner image so that a pair of toner images of a straight line and a diagonal line extending in the main scanning direction are formed. Then, image formation of a yellow toner image is performed. Then, these images are transferred and fixed on a sheet material to form a first toner image P1 and conveyed to the second image forming apparatus.

Before and after this, the image forming unit of the second image forming apparatus forms a pair of second toner images P2 of straight lines and diagonal lines extending in the main scanning direction.
The first detection unit 301 detects the first toner image P1 shifted in color and position on the sheet discharged from the first image forming apparatus. After the detection, the second toner image P2 is temporarily stored in the sheet material. Is transcribed. This state is shown in FIG. Immediately after the transfer, the second toner image P2 is transferred to the retransfer roller or the fixing roller, and the second detection unit 306 detects the second toner image P2 on the retransfer roller or the fixing roller. In FIG. 6, the first toner image and the second toner image are formed at the center and at the three ends, and the first detection unit 301 and the second detection unit 306 correspond to the toner image. The detection accuracy is improved by a plurality of detections.

  From the detection information obtained in this way, a positional deviation in the main scanning direction and a positional deviation in the sub-scanning direction are detected. The detection procedure is basically the same as described above. That is, assuming that the transport speeds of the transport systems of the first image forming apparatus 1 and the second image forming apparatus 2 are constant, the distance interval between the linear images of the respective colors is essentially constant, and the detection interval Is a fixed time interval. However, if there is a timing shift (image shift) in the sub-scanning direction (conveyance direction) of the writing unit, the distance interval with the black color linear image as a base point changes, and a time shift occurs in detection. It can be detected as a deviation amount in the scanning direction.

  Timing deviation (image deviation) in the main scanning direction of each writing unit is detected by a hatched image. That is, for example, when the cyan oblique line image is shifted in the main scanning direction (belt width direction) with respect to the black oblique line image, the cyan oblique line based on the black linear image at the detection position of the reflective optical sensor. Since the distance interval to the image changes and a time shift occurs in detection, it can be detected as a shift amount in the main scanning direction. However, in the detection of the deviation amount in the main scanning direction, if there is a deviation amount in the sub scanning direction, the deviation amount in the pure main scanning direction is considered in consideration of the temporal deviation based on the deviation amount in the sub scanning direction. Only to detect.

  Each color shift of the first toner image obtained in this way is fed back to the writing unit of the first image forming apparatus, and the second toner image shift relative to the first toner image is the second image. By feeding back to the writing unit on the forming apparatus side, the alignment of the toner image of each color and the alignment of the second toner image by the first image forming apparatus can be performed simultaneously.

  Although the image forming system according to the present embodiment has been described above, the above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto. Various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... 1st image forming apparatus 101 ... Photosensitive drum 102 ... Cleaning device 103 ... Charging roller 104 ... Developing device 105 ... Writing unit 106 ... Driving roller 107 ... Driven roller 108 ... Secondary transfer counter roller 109 ... Intermediate transfer belt 110 ... Primary transfer roller 111 ... Cleaning device 112 ... Drive roller 113 ... Follower roller 114 ... First transport belt 115 ... Secondary transfer roller 116 ... Registration roller 117 ... Transport roller 118 ... Discharge port 119 ... Fixing roller 120 ... Pressure roller Reference Signs List 121 ... paper feed tray 122 ... paper feed roller 2 ... second image forming apparatus 201 ... photosensitive drum 202 ... cleaning device 203 ... charging roller 204 ... developing device 205 ... writing unit 206 ... drive roller 207 ... driven roller 208 ... second Carrying Belt 209, transfer roller 210, registration roller 211, transport roller 212, receiving port 213, fixing roller 214, pressure roller 215, transport path 3, toner image misregistration correction device 301, first detection unit 302, light emitting element 303. Light receiving element 304. Retransfer roller 305 Retransfer roller facing roller 306 Second detection unit 307 Light emitting element 308 Light receiving element 309 Cleaning unit 310 Fixing roller 311 Cleaning roller S Sheet material N Transfer Nip P1 First toner image P2 Second toner image

JP 2002-341619 A JP 2000-131875 A JP 2002-229293 A JP 2004-361827 A JP 2005-156950 A JP 2009-109794 A JP 2009-0775155 A

Claims (10)

A toner image composed of a first toner image formed by the first image forming apparatus and a second toner image formed by the second image forming apparatus provided in the first image forming apparatus. An image shift correction device for a toner image that corrects the image shift of
The toner of the second toner image is a toner that is white when unfixed and becomes transparent after fixing, or a toner that is white when unfixed and after fixing,
The second image forming apparatus includes a conveyance path through which the sheet material is conveyed, and a transfer unit that is provided in the middle of the conveyance path and transfers the second toner image to the sheet material to which the first toner image is fixed. And
A first detection unit that is provided upstream of the transfer unit with respect to the transfer unit and detects the first toner image of the sheet material being conveyed;
A transfer target provided on the downstream side of conveyance with the transfer unit as a base point, to which the second toner image being transferred transferred to the sheet material in the transfer unit is transferred;
A second detection unit for detecting the second toner image transferred to the transfer object;
Using the detection information of the first detection unit and the detection information of the second detection unit, an image shift amount between the first toner image and the second toner image is detected, and the image shift amount An image misalignment correction control unit that controls the operation of the second image forming apparatus or controls the operations of both the first image forming apparatus and the second image forming apparatus so that the image misalignment can be corrected. ,
An image shift correction apparatus for a toner image, comprising: A fixing body for fixing the toner image transferred to the sheet material at the transfer unit to the sheet material is provided on the downstream side of conveyance from the transfer unit as a base point;
2. The toner image misregistration correction apparatus according to claim 1, wherein the transfer member is provided between the transfer unit and the fixing member. A fixing body for fixing the toner image transferred to the sheet material at the transfer unit to the sheet material is provided on the downstream side of conveyance from the transfer unit as a base point;
The transfer target is also used as the fixing member, and is configured to be able to transfer the second toner image transferred to the sheet material to the fixing member and to control the fixing temperature of the fixing member. The image shift correction apparatus for a toner image according to claim 1, wherein   4. The toner according to claim 1, further comprising a cleaning unit that is provided in contact with the transfer target and capable of removing the second toner image from the transfer target. Image misalignment correction apparatus.   5. The toner image according to claim 4, wherein the cleaning unit and the transfer target are supported by a common case, and the toner image is configured as a cartridge that can be attached to and detached from the second image forming apparatus. Image shift correction device.   The second toner image can be transferred to the sheet material by the transfer unit within a range corresponding to the peripheral length of the transfer object from the front end of the sheet material. The image shift correction device for a toner image according to any one of claims 1 to 5.   7. The toner image misregistration correction apparatus according to claim 1, wherein each of the first detection unit and the second detection unit includes a reflective optical sensor. The image misalignment correction control unit is configured to display an image when the temperature of the fixing body is equal to or lower than a temperature at which the fixing body can be fixed, such as when the main power of the first image forming apparatus and the second image forming apparatus are turned on 8. The image misalignment correction operation can be executed before a temperature at which the fixing body can be fixed when a formation request is made. The image shift correction device for a toner image according to item 2. An image forming apparatus comprising the toner image misregistration correction apparatus according to claim 1 . An image shift correction device for a toner image according to any one of claims 1 to 7 , the first image forming device, and the second image forming device.
An image forming system, wherein the first image forming apparatus and the second image forming apparatus are configured to be capable of independently forming an image even when they are not provided .

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