JP2009143109A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming different images at high speed by improving processing speed utilizing the characteristic of magnetism that deterioration of a latent image is hardly caused. <P>SOLUTION: The image forming apparatus 100 includes: a magnetic latent image drum 10 holding a magnetic latent image on its outer peripheral surface having water repellency; a magnetic head 12 forming the magnetic latent image on the magnetic drum 10 on the basis of image data; an intermediate transfer body 16 to the outer peripheral surface of which the magnetic latent image held on the magnetic drum 10 is transferred; a paper feeding device 40 feeding a recording medium to which the magnetic latent image transferred to the intermediate transfer body 16 is transferred; a first motor drive circuit 36 driving and rotating the magnetic drum 10; a second motor drive circuit 37 driving and rotating the intermediate transfer body 16; a third motor drive circuit 38 driving the paper feeding device 40 in a recording medium feeding direction; and a control part which calculates the formation amount of the magnetic latent image by the magnetic head 12 and controls the first motor drive circuit, the second motor drive circuit and the third motor drive circuit on the basis of the formation amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  As an image forming apparatus method, an indirect marking method such as a xerographic method is known. In this method, first, a latent image is exposed on an image carrier such as a photoconductor with a laser exposure device or a light emitting diode (LED), and then transferred to paper, or once transferred to an intermediate transfer member such as a belt. After that, it is secondarily transferred to paper. In this case, it is necessary to repeat the same operation when transferring a plurality of the same images. Therefore, there is no change in the data transfer to the exposure unit, which is the biggest bottleneck in improving the processing speed, and the processing cannot be simplified. Therefore, the processing speed does not change even when processing the same image.

  Also, when printing multiple copies of the same image, if a block is created, it can be processed at high speed only by transferring it to paper. However, if the images differ for each sheet, the block is recreated each time. The processing speed is extremely slow and the cost is extremely high.

  On the other hand, in the marking method using magnetography, a magnetic latent image is formed on the magnetic drum by the magnetic head, as in the indirect marking method such as the normal xerography method. In the development area, development is performed by supplying magnetic toner onto the magnetic drum in accordance with the magnetic force of the formed magnetic latent image. Thereafter, in the transfer area, the image is primarily transferred to an image holding member such as a transfer drum and secondarily transferred to a recording medium such as paper. Further, the recording medium after transfer is transported to the fixing area and subjected to a fixing process to complete the printing.

  As this magnetography, a so-called dry image forming apparatus using powdered magnetic toner has been proposed (for example, see Patent Documents 1 and 2). As a specific process, for example, the magnetic toner is supplied by a supply roller disposed at a distance from the magnetic recording medium. The supply roller holds the magnetic toner layer on its surface, brings the magnetic toner layer into contact with the magnetic recording medium, and supplies and adheres the magnetic toner to the magnetic latent image of the magnetic recording medium.

Further, an image forming apparatus (so-called liquid magnetography) using a liquid developer in which magnetic toner is dispersed in a liquid has been studied (for example, see Patent Documents 3 and 4). In this process, since the toner is contained in the liquid, a problem such as a toner cloud does not occur even if the toner particle size is reduced to improve the image quality.
Japanese Patent Laid-Open No. 6-4008 JP-A-9-156150 Japanese Patent Publication No. 5-87834 Japanese Patent Laid-Open No. 5-18827

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of improving the processing speed due to the magnetic property of little latent image deterioration and forming different images at high speed.

  In order to solve the above-mentioned object, the image forming apparatus according to claim 1 includes a magnetic latent image holding body that holds a magnetic latent image on an outer peripheral surface having water repellency, and the magnetic latent image holding body based on image data. Magnetic latent image forming means for forming a magnetic latent image thereon, intermediate transfer means for transferring the magnetic latent image held on the magnetic latent image holding body onto the outer peripheral surface, and magnetism transferred to the intermediate transfer means A recording medium conveying means for conveying a recording medium to which the latent image is transferred; a first driving means for rotating the magnetic latent image holder; a second driving means for rotating the intermediate transfer means; and the recording medium. Third drive means for driving the transport means in the recording medium transport direction, and a magnetic latent image formation amount by the magnetic latent image forming means is calculated, and the first drive means and the second drive means are calculated based on the formation amounts. And control means for controlling the third drive means, Eteiru.

  The image forming apparatus according to claim 2, further comprising: a magnetic latent image erasing unit that partially erases the magnetic latent image held on the magnetic latent image holding member in the image forming apparatus according to claim 1, The magnetic latent image forming unit forms a magnetic latent image on the portion erased by the magnetic latent image erasing unit.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the control unit is erased by the formation amount of the magnetic latent image formed by the magnetic latent image forming unit or the magnetic latent image erasing unit. The speeds of the first drive means, the second drive means, and the third drive means are changed based on the erase amount of the magnetic latent image.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect of the present invention, the image forming apparatus further includes image data storage means for sequentially storing image data, and the control means includes new image data and the image data. The erasure amount or the formation amount is calculated by comparing the image data stored in the image data.

  The image forming apparatus according to claim 5 further includes image information input means for inputting image data update information by a user in the image forming apparatus according to claim 3, wherein the control means is input by the image information input means. Based on the obtained image information, the erasure amount or the formation amount is calculated.

  6. The image forming apparatus according to claim 3, wherein the control unit includes an area of a magnetic latent image formed by the magnetic latent image forming unit, and sub-scanning by the magnetic latent image forming unit. The erasure amount or the formation amount is calculated based on at least one of the direction length and the main scanning direction length by the magnetic latent image forming means.

  According to the first aspect of the present invention, the processing speed can be improved by controlling the drive system based on the formation amount of the magnetic latent image.

  According to the second aspect of the present invention, the processing speed can be improved by forming the magnetic latent image only in the erased portion of the magnetic latent image.

  According to the third aspect of the present invention, the processing speed can be improved by changing the speed of the drive system based on the formation amount or erasure amount of the magnetic latent image.

  According to the fourth aspect of the present invention, the amount of magnetic latent image formed or erased can be calculated by comparing previous image data with new image data.

  According to the fifth aspect of the present invention, the user can designate the amount of formation or erasure of the magnetic latent image.

  According to the sixth aspect of the present invention, the amount of magnetic latent image formed or erased is at least the area of the magnetic latent image, the sub-scanning direction length by the magnetic latent image forming means, and the main scanning direction length by the magnetic latent image forming means. It can be calculated based on one.

  In the present embodiment, an image forming apparatus that develops a magnetic latent image formed on a magnetic latent image holding member using a liquid developer in which magnetic toner is dispersed in an aqueous medium to form an image, so-called liquid magneto The graphic will be described. The image forming apparatus is not limited to the one using a liquid developer, and may be a so-called dry image forming apparatus using powder magnetic toner.

  The image forming apparatus according to the present embodiment includes a magnetic latent image holding member that has a water-repellent surface and can hold a magnetic latent image, and a magnetic latent image forming unit that forms a magnetic latent image on the magnetic latent image holding member. A developer storing means for storing a liquid developer containing magnetic toner and an aqueous medium, and holding a magnetic latent image on which the magnetic latent image is formed in order to visualize the magnetic latent image as a toner image Developer supplying means for supplying to the body; transfer means for transferring the toner image to a recording medium; and demagnetizing means for demagnetizing the magnetic latent image on the magnetic latent image holding member.

  In this embodiment, a liquid developer in which magnetic toner is dispersed in an aqueous medium is used as a developer for a magnetic latent image. Here, the aqueous medium means a solvent containing 50% by mass or more of water. “Water” means purified water such as distilled water, ion exchange water, ultrapure water, and the like.

  In so-called liquid magnetography using a liquid developer, the toner image on the magnetic latent image carrier immediately after development usually contains a large amount of excess developer, so that the toner image is transferred to a recording medium such as paper. In some cases, it is necessary to provide a drying step before removing the excess developer.

  In this embodiment, since an aqueous medium is used as a dispersion medium in the liquid developer, since water has a large surface tension due to hydrogen bonding, a liquid at the time of development can be obtained by combining with a water-repellent magnetic latent image holder described later. Even if the developer contacts the magnetic latent image holding member, the liquid as the dispersion medium is difficult to transfer to the magnetic latent image holding member, and the toner image is transferred to the recording medium without leaving the liquid on the magnetic latent image holding member. be able to. Therefore, there is no need for a squeeze roller or the like for removing the residual solvent on the magnetic latent image holding member, and the recording medium on which the toner image is transferred need hardly be dried.

  Further, during development, an aqueous medium having a large surface tension hardly gets wet and spreads on the surface of the magnetic latent image holding member. On the other hand, the magnetic toner having high mobility and being uniformly dispersed in the developer transfers to the magnetic latent image only by the magnetic force simultaneously with the contact with the magnetic latent image holding member, so that the image fog is hardly generated. A development environment that is unlikely to occur is created.

  In the present specification, “uniform” with respect to the dispersion and the like means that there are no aggregates of such a size that more than ten primary particles such as magnetic powder and polymer particles are gathered in the system. Say. The same applies to the following.

  The image forming process applied to the present embodiment includes a so-called electrophotographic process, a process of forming an electrostatic latent image with ions or the like on a dielectric (ionography), and image information by heat of a thermal head on a charged dielectric. In this process, the electrostatic latent image is not used, such as a process of forming an electrostatic latent image according to the above, but a process of forming a toner image by forming a magnetic latent image on a magnetic latent image holding member.

  In the following, an image forming apparatus using a magnetic development process using a liquid developer in the present embodiment will be briefly described.

  FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment. The image forming apparatus 100 includes a magnetic drum 10, a magnetic head 12, a developing device 14, an intermediate transfer body 16, a cleaner 18, a demagnetizing device 20, and a transfer fixing roller 28. The magnetic drum 10 has a cylindrical shape, and a magnetic head 12, a developing device 14, an intermediate transfer member 16, a cleaner 18, and a demagnetizing device 20 are sequentially provided on the outer periphery of the magnetic drum 10.

  The operation of the image forming apparatus 100 will be briefly described below.

  First, the magnetic head 12 is connected to an information device (not shown), for example, and receives binarized image data sent from the information device. The magnetic head 12 forms a magnetic latent image 22 on the magnetic drum 10 by emitting lines of magnetic force while scanning the side surface of the magnetic drum 10. In FIG. 1, the magnetic latent image 22 is indicated by a hatched portion in the magnetic drum 10.

  The developing device 14 includes a developing roller 14a and a developer storage container 14b. The developing roller 14a is provided so that a part thereof is immersed in the liquid developer 24 stored in the developer storage container 14b.

  The liquid developer 24 includes an aqueous medium and toner particles. The toner particles are a magnetic toner including a magnetic material.

  In the liquid developer 24, the toner particles are uniformly dispersed. For example, the liquid developer 24 is further stirred by a stirring member provided in the developer storage container 14 b at a predetermined rotation speed, so that the liquid The positional variation in the concentration of toner particles in the developer 24 is reduced. As a result, the liquid developer 24 with reduced toner particle density variation is supplied to the developing roller 14a rotating in the direction of arrow A in the figure.

  The liquid developer 24 supplied to the developing roller 14a is transported to the magnetic drum 10 while being limited to a constant supply amount, and the magnetic latent image is at a position where the developing roller 14a and the magnetic drum 10 are close (or in contact). 22 is supplied. As a result, the magnetic latent image 22 is visualized and becomes a toner image 26.

  The developed toner image 26 is transported to the magnetic drum 10 rotating in the direction of arrow B in the figure and transferred to the recording medium 30. In this embodiment, the toner image 26 is transferred from the magnetic drum 10 before being transferred to the recording medium 30. In order to improve the transfer efficiency to the recording medium 30 including the separation efficiency of the toner image 26 and to fix the toner image 26 simultaneously with the transfer to the recording medium 30, the toner image 26 is once transferred to the intermediate transfer body 16.

  Transfer to the intermediate transfer member 16 is preferably performed by shearing transfer (non-electric field transfer) because the toner particles have almost no charge. Specifically, the magnetic drum 10 that rotates in the direction of arrow B and the intermediate transfer member 16 that rotates in the direction of arrow C are brought into contact with each other with a certain nip (contact surface having a contact width in the moving direction) to the toner image 26. Thus, the toner image 26 is transferred onto the intermediate transfer member 16 by an attractive force greater than the magnetic force with the magnetic drum 10. At this time, a peripheral speed difference may be provided between the magnetic drum 10 and the intermediate transfer member 16.

  Next, the toner image 26 conveyed in the direction of arrow C by the intermediate transfer member 16 is transferred to the recording medium 30 at a position where the toner image 26 is in contact with the transfer fixing roller 28, and is simultaneously fixed.

  The transfer fixing roller 28 sandwiches the recording medium 30 between the intermediate transfer body 16 and closely contacts the toner image 26 on the intermediate transfer body 16 with the recording medium 30. As a result, the toner image 26 can be copied onto the recording medium 30 and simultaneously the toner image 26 can be fixed on the recording medium 30. The fixing of the toner image 26 can be performed only by pressure depending on the characteristics of the toner, or may be performed by pressing and heating by providing a heat generating body on the transfer fixing roller 28.

  On the other hand, in the magnetic drum 10 in which the toner image 26 is transferred to the intermediate transfer member 16, the transfer residual toner is conveyed to a contact position with the cleaner 18 and collected by the cleaner 18. After cleaning, the magnetic drum 10 rotates and moves to the demagnetization position while holding the magnetic latent image 22.

  The degaussing device 20 erases the magnetic latent image 22 formed on the magnetic drum 10. The cleaner 18 and the degaussing device 20 return the magnetic drum 10 to a state in which there is no variation in the magnetization state of the magnetic layer before image formation. By repeating the above operation, images successively sent from the information device are continuously formed in a short time. The magnetic head 12, the developing device 14, the intermediate transfer member 16, the transfer fixing roller 28, the cleaner 18, and the demagnetizing device 20 provided in the image forming apparatus 100 are all operated in synchronization with the rotation speed of the magnetic drum 10. ing.

  Next, FIG. 2 is a functional block diagram of the image forming apparatus 100 according to the present embodiment. As shown in the figure, the image forming apparatus 100 includes an image processing unit 31, a control unit 32, a previous image storage unit 33, a user input unit 34, an image memory 35, a first motor drive circuit 36, and a second motor drive circuit. 37, a third motor drive circuit 38, a magnetic drum rotation motor 41, an intermediate transfer body rotation motor 42, a paper transport motor 43, a magnetic head 12, a degaussing device 20, a magnetic drum 10, an intermediate transfer body 16, and a paper transport device 40. Consists of.

  The image processing unit 31 performs binarization processing on the input image data. The binarized image data is transmitted to the control unit 32 and the previous image storage unit 33.

  The control unit 32 transmits the received binarized image data to the magnetic head 12 via the image memory 35. The magnetic head 12 forms a magnetic latent image on the magnetic drum 10 based on the received image data.

  Further, the control unit 32 compares the previous image data stored in the previous image storage unit 33 with the new image data received as the input image, or based on the position designated by the user via the user input unit 34. Thus, the update position of the image data and the respective driving speeds of the magnetic drum 10, the intermediate transfer member 16, and the paper transport device 40 are calculated.

  The calculated update position data is transmitted to the degaussing device 20. The degaussing device 20 erases the magnetic latent image on the magnetic drum 10 based on the received update position data.

  The calculated drive speed data is transmitted to the first motor drive circuit 36, the second motor drive circuit 37, and the third motor drive circuit 38, respectively. The first motor drive circuit 36 drives the magnetic drum rotation motor 41 based on the transmitted drive speed data. The second motor drive circuit 37 drives the intermediate transfer member rotation motor 42 based on the transmitted drive speed data. The third motor drive circuit 38 drives the paper transport motor 43 based on the transmitted drive speed data. As a result, the magnetic drum 10 and the intermediate transfer member 16 are rotated, and the paper transport device 40 transports the paper.

  Next, an operation flow of the image forming apparatus 100 based on the marking method using liquid magnetography according to the present embodiment will be described with reference to a flowchart of FIG.

<First Embodiment>
In the first embodiment, a completely different image is output one by one, and FIG. 3A shows the flow of the operation.

  First, in step 102, the first motor drive circuit 36 drives the motor to rotate the magnetic drum 10 based on the drive speed data transmitted from the control unit 32. Then, the magnetic head 12 forms a magnetic latent image on the rotating magnetic drum 10.

  In step 104, the developing device 14 supplies the magnetic toner according to the magnetic force of the magnetic latent image formed on the rotating magnetic drum 10 to perform development. As a result, the magnetic latent image is visualized and becomes a toner image.

  In step 106, the second motor drive circuit 37 drives the motor based on the drive speed data transmitted from the control unit 32 to rotate the intermediate transfer body 16. As a result, the toner image on the magnetic drum 10 is primarily transferred to the intermediate transfer member 16.

  Further, the third motor drive circuit 38 drives the motor based on the drive speed data transmitted from the control unit to move the paper transport device 40 in the paper transport direction. As a result, the toner image on the intermediate transfer body 16 is secondarily transferred onto the paper on the paper transport device 40.

  In step 108, the cleaner 18 wipes off the toner that is not transferred during transfer and remains on the magnetic drum 10. As a result, deterioration of image quality during the next image formation is prevented.

  Finally, in step 110, the degaussing device 20 erases the magnetic latent image on the magnetic drum 10, and then returns to step 102 to repeat the above processing.

  As described above, in the first embodiment, a continuous print is output by performing the above-described processing cyclically.

<Second Embodiment>
In the print cycle of the first embodiment, since image data transfer for forming a latent image that is performed every time is required, high-speed data transfer is required. Therefore, when outputting completely different images one sheet at a time, all processes are performed for each sheet as in other indirect marking methods, and it is difficult to realize high productivity by increasing the process speed. is there. Therefore, in the second embodiment, when the same image is output, the process speed is increased by performing the following processing.

  In the second embodiment, the same image is continuously output, and FIG. 3B shows the flow of the operation.

  In this embodiment, the steps from “magnetic latent image formation” in step 102 to “cleaning” in step 108 are the same as those in the first embodiment.

  Here, in the liquid magnetography according to the present embodiment, the latent image is formed by magnetism, and the magnetic latent image remains semipermanently. Therefore, when the same image is continuously output, it is necessary to rewrite the latent image every time. There is no. That is, it is possible to form an image simply by repeating the process of “development → transfer → cleaning”.

  Accordingly, after step 108 is completed, it is possible to perform image formation simply by returning to step 104 and repeating the processing from “development” in step 104 to “cleaning” in step 108.

  As described above, in the second embodiment, high-speed data transfer for forming a magnetic latent image is not necessary, and the process speed is increased.

<Third Embodiment>
The third embodiment is a case of outputting an image in which most of the images are the same but only a part of the data is different, and FIG. 3C shows the flow of the operation.

  In this embodiment, “magnetic latent image formation” in step 102 to “cleaning” in step 108 are the same as those in the first and second embodiments.

  Here, in general, printed materials that require high-speed on-demand are the same in most images, such as direct mail, tickets, and specifications, but there are many data that differ only in part. For example, the specification shown in FIG. 4 is the same for a standard cell, company name, various information, advertisements, etc., and only the user's name and usage amount (number) are different. When outputting such an image, in the first specification shown in FIG. 4A, as shown in FIG. 4B, only the magnetic latent image in a region 50 different for each image is demagnetized, A magnetic latent image is formed only in the demagnetized area, and the second and subsequent specifications are output as shown in FIG.

  Therefore, after step 108 is completed, in step 112, the control unit 32 obtains areas where the first and second images are different, that is, an area where a new latent image is to be written, and the update position data is obtained. Send to the degausser. The degaussing device 20 partially demagnetizes the magnetic latent image on the magnetic drum 10 based on the received update position data.

  In step 114, the magnetic head 12 partially forms a magnetic latent image in the area where the partial demagnetization of the magnetic drum 10 has been performed according to the image data to be rewritten. In this case, the control unit 32 obtains an area for writing a new latent image, calculates the driving speeds of the magnetic drum 10, the intermediate transfer body 16, and the paper transporting device 40 based on the area, and calculates the first motor driving circuit 36. , To the second motor drive circuit 37 and the third motor drive circuit 38. Each motor drive circuit 36, 37, 38 drives a motor that rotates the magnetic drum 10 based on the received drive speed, drives a motor that rotates the intermediate transfer member 16, and moves the paper transport device 40 in the paper transport direction. The motor to be moved is driven.

  After step 114 is completed, the process returns to step 104, and the process from “development” in step 104 to “partial magnetic latent image formation” in step 114 is repeated to form the second and subsequent latent images.

  As described above, in the third embodiment, the area of the new latent image writing area in the second and subsequent latent image formations is smaller than that in the case where the entire image area is rewritten. In the example of FIG. 4C, the area of the new latent image writing area is about half at the maximum as judged from the size of the table, so that the process speed is doubled without increasing the data transfer speed.

  Here, the area and position of the area where the new latent image is written are calculated from different pixels by taking the difference between the previous image data and the image data to be written from now on, but the calculation method is limited to this method. Is not to be done. The user may directly specify, or when the image is binary data, a logical operation (exclusive logical operation or the like) may be used.

  Although the area of the new latent image writing area is used for determining the process speed here, the length of the magnetic head 12 in the sub-scanning direction or the main scanning direction, the latent image erasing / forming time, and the like can also be used.

  In addition, this invention is not limited to embodiment mentioned above, It can apply also to what changed the design within the range described in the claim.

1 is a schematic configuration diagram of an image forming apparatus according to an exemplary embodiment. 1 is a functional block diagram of an image forming apparatus according to an embodiment. 3 is a flowchart showing a flow of operations of the image forming apparatus according to the present embodiment. It is a figure which shows the example of an output of the specification which newly writes only in a one part area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic drum 12 Magnetic head 16 Intermediate transfer body 20 Demagnetizing device 31 Image processing part 32 Control part 33 Previous image storage part 34 User input part 35 Image memory 36 1st motor drive circuit 37 2nd motor drive circuit 38 3rd motor drive circuit 40 Paper Conveying Device 41 Magnetic Drum Rotating Motor 42 Intermediate Transfer Medium Classic Motor 43 Paper Conveying Motor 100 Image Forming Apparatus

Claims (6)

A magnetic latent image holding body for holding a magnetic latent image on an outer peripheral surface having water repellency;
Magnetic latent image forming means for forming a magnetic latent image on the magnetic latent image holding member based on image data;
Intermediate transfer means for transferring the magnetic latent image held on the magnetic latent image holding body onto the outer peripheral surface;
A recording medium conveying means for conveying a recording medium to which the magnetic latent image transferred to the intermediate transfer means is transferred;
First driving means for rotationally driving the magnetic latent image holding body;
Second driving means for rotationally driving the intermediate transfer means;
Third driving means for driving the recording medium conveying means in the recording medium conveying direction;
Control means for calculating the amount of magnetic latent image formed by the magnetic latent image forming means and controlling the first drive means, the second drive means and the third drive means based on the formation amount;
An image forming apparatus. Magnetic latent image erasing means for partially erasing the magnetic latent image held on the magnetic latent image holding body,
The image forming apparatus according to claim 1, wherein the magnetic latent image forming unit forms a magnetic latent image on a portion erased by the magnetic latent image erasing unit.   The control unit is configured to control the first driving unit and the second driving unit based on a magnetic latent image forming amount formed by the magnetic latent image forming unit or a magnetic latent image erasing amount erased by the magnetic latent image erasing unit. The image forming apparatus according to claim 2, wherein the speeds of the first driving unit and the third driving unit are changed. Image data storage means for sequentially storing the image data,
4. The image forming apparatus according to claim 3, wherein the control unit calculates the erasure amount or the formation amount by comparing new image data with the image data stored in the storage unit. It further comprises image information input means for inputting image data update information by the user,
The image forming apparatus according to claim 3, wherein the control unit calculates the erasure amount or the formation amount based on the image information input by the image information input unit.   The control means is based on at least one of the area of the magnetic latent image formed by the magnetic latent image forming means, the sub-scanning direction length by the magnetic latent image forming means, and the main scanning direction length by the magnetic latent image forming means. The image forming apparatus according to claim 3, wherein the erasing amount or the forming amount is calculated.

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