JP2006154579A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents filming of particulates to be generated on the outside of recording material width of an intermediate transfer body. <P>SOLUTION: The image forming apparatus has a primary transfer device 22 which transfers a toner image on the intermediate transfer body 10, a secondary transfer device 62 which transfers the toner image held on the intermediate transfer body 10 on recording materials with various sizes and a mechanism for inputting the toner image on the intermediate transfer body 10 from a photoreceptor 40 at timing other than that of image formation to the recording materials when there is use of a recording material with width less than that of the intermediate transfer body 10 at least for once. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that forms an image with toner used for image formation by an electrostatic copying process, such as a copying machine, a facsimile machine, and a printer.

  Conventionally, as a measure for preventing toner filming generated on an image carrier such as a photosensitive drum, a means for applying a thin film of fine particles having a toner filming prevention function to the surface of the image carrier has been proposed. Similarly, as disclosed in Patent Document 1, means for applying the fine particles has been proposed for toner filming generated in the intermediate transfer member. However, as shown in Patent Document 2, when toner is transferred from the image carrier to the intermediate transfer member, a relational expression of α ≧ β may be established between the relative friction coefficients of the two. preferable. Here, the relative friction coefficient between the image carrier and the contacted body that is in frictional contact with this is α, and the relative friction coefficient between the intermediate transfer member and the contacted body that is in frictional contact with this is β. If the above relational expression does not hold, a transfer defect is likely to occur, and the toner inside the character part or the fine line part in the image, which is said to be “worm-eaten”, will be whitened without being transferred. An image defect may occur.

Furthermore, it is known that the value representing the transfer performance called “transfer rate” is also deteriorated by dividing the amount of toner on the image carrier before the transfer process by the amount of toner transferred onto the intermediate transfer body after the transfer process. It has been. For this reason, when filming of the intermediate transfer member is difficult to occur without applying the fine particles, the fine particles applied to the image carrier are transferred to the intermediate transfer member (from the image carrier to the fine particles). In some cases, a method of preventing toner filming and controlling the relative friction coefficient may be taken without providing a mechanism for applying the fine particles to the intermediate transfer member. This method is advantageous in terms of cost since the intermediate transfer member does not have a coating mechanism.
For example, in Patent Document 3, when the width with respect to the supply direction of the recording paper is narrower than a predetermined determination reference width, at least an area that does not face the recording paper in the transferable area of the intermediate transfer belt and the supply direction of the recording paper There is disclosed an image forming apparatus provided with control means for executing control for forming a toner band (band-shaped toner image) crossing the area in a specific area outside the side edge of the image forming apparatus. However, this increases the cost due to the waste toner, and the collection box becomes large due to the increase in the toner to be collected, which is disadvantageous in design.

In addition, in order to prevent toner filming of the intermediate transfer member by supplying (wrapping around) the fine particles from the image carrier, it is required to increase the amount of the fine particles applied to the image carrier. This is because the coating amount must be sufficient to prevent toner filming on both the image carrier and the intermediate transfer member. On the other hand, the fine particles applied to the intermediate transfer member are sequentially consumed by being attracted or scraped by toner, a cleaning member, a recording material, or the like. The cleaning member is usually provided to cover the entire width of the intermediate transfer member, more precisely, at least the maximum width of the usable recording material. However, the toner particles input to the intermediate transfer member and the position and width of the recording material are used. In general, the value varies depending on the convenience of the user of the image forming apparatus.
As described above, the supply of the fine particles is uniformly performed at least in the maximum width of the recording material, but the consumption amount is various and can be changed. In particular, when passing a recording material that is less than the maximum width of the usable recording material (hereinafter referred to as a small size recording material), the left and right ends of the recording material that the width of the small size recording material of the intermediate transfer member does not cover In the outer portion, the consumption of the fine particles by the toner and the recording material is completely eliminated. Therefore, even if the supply amount of the fine particles from the image carrier is necessary and sufficient in the portion covered by the image portion and the recording material, It becomes excessive in the part. In such an excessive supply portion of fine particles, filming of the intermediate transfer member due to the accumulation of fine particles occurs, and a recording material having a width that covers the filming portion after the occurrence of filming is used. When image formation is performed, there is a possibility that an abnormal image called blur or image flow may occur in the filming portion. (Hereinafter, this type of filming is called the fine particle filming.)

Japanese Patent Laid-Open No. 06-337598 Japanese Patent Laid-Open No. 06-332324 JP 2001-175090 A

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus which prevents filming of fine particles generated outside the recording material width of an intermediate transfer member.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. The image forming apparatus of the present invention has a mechanism that can be repeatedly used by rotating, and an image carrier capable of carrying a latent image, and a charging member in contact with or close to the surface of the image carrier. A charging device that charges the image bearing member, a latent image forming device that forms a latent image on the image bearing member, a developing device that develops toner by attaching the toner to the latent image on the image bearing member, and the image bearing member that moves while contacting the image bearing member. A primary transfer device that forms a transfer electric field between the intermediate transfer member and the toner image formed on the image carrier onto the intermediate transfer member, and the toner image held on the intermediate transfer member in various sizes. In the image forming apparatus having at least one secondary transfer device for transferring onto the recording material, a recording material having a width less than the intermediate transfer member is used at least once. At the timing other than image formation The toner image is input onto the intermediate transfer member.
2. The image forming apparatus of the present invention is further characterized in that a toner image input from the image carrier to the intermediate transfer member is input continuously or discontinuously to the intermediate transfer member.
3. The image forming apparatus of the present invention further provides a toner image input from the image carrier to the intermediate transfer member when the intermediate transfer member width L1 is the width L2 of the used recording material. Input is performed continuously or discontinuously into a portion included in the width L1 and other than the width L2 of the used recording material (a portion in L1 that does not overlap with L2). .
4). The image forming apparatus of the present invention is further characterized in that the secondary transfer device can contact and separate from the intermediate transfer member.
5. The image forming apparatus of the present invention can further separate at least one or more image carriers from the intermediate transfer member when there are a plurality of image carriers.
6). The image forming apparatus of the present invention is further characterized in that the cleaning member can be brought into contact with and separated from the intermediate transfer member.
7). The image forming apparatus of the present invention is further characterized in that the developing device collects toner remaining on the intermediate transfer body after the secondary transfer device that is in contact with or separated from the secondary transfer device.
8). The image forming apparatus of the present invention is further characterized in that toner input to the intermediate transfer member is performed in a single color.
9. Further, the image forming apparatus of the present invention is further characterized in that the residual toner recovery in the developing device is performed by a developing device having the same color as the toner input to the intermediate transfer member.
10. Further, the image forming apparatus of the present invention is further characterized in that black toner is used to input toner to the intermediate transfer member.

  According to the present invention, in the image forming apparatus according to the present invention, the toner input from the image carrier can reduce the accumulation of excessive fine particles, and the fine particle filming at the toner input portion is achieved by the means for solving the above problems. Can be suppressed. Further, since the toner is input from the image carrier over the width of the maximum size recording material that can be used, it is possible to prevent the fine particle filming from occurring in the entire image area.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the description, specific member names are used to facilitate understanding of the invention, but it should be clearly stated that the scope of the present invention is not limited thereby.

First, the operation of the image forming apparatus of the present invention will be described. FIG. 1 shows the entire image forming apparatus. The scanner unit 300 sets a document on the document table 30 of the document conveyance unit 400 or opens the document conveyance unit 400 to set a document on the contact glass 31 of the scanner unit 300 and closes the document conveyance unit 400. And hold down the document. When a start switch (not shown) is pressed, the original is conveyed onto the contact glass 31 when the original is set on the original conveying section 400, and immediately after the original is set on the other contact glass 31, the scanner The part 300 is driven to travel the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source 32 and further reflects the reflected light from the document surface toward the second traveling body 34 and reflects by the mirror of the second traveling body 34 to form the imaging lens 35. Then, the image information is read through the reading sensor 36. The read image information is sent to this control unit. Based on the image information received from the scanner unit 300, the control unit controls a laser, an LED, and the like (not shown) disposed in the exposure device 21 of the image forming unit 100 to face the photoconductors 40Bk, 40Y, 40M, and 40C. Then, the laser writing light L is irradiated. By this irradiation, electrostatic latent images are formed on the surfaces of the photoreceptors 40Bk, 40Y, 40M, and 40C.
The paper feed unit 200 includes a plurality of paper feed cassettes 44, and feeds the recording material from the paper feed cassette 44 by the paper feed roller 42. The fed recording material is separated by the separation roller 45 and sent to the paper feed path 46. The recording material is transported to the paper feed path 48 of the image forming unit 100 by the transport roller 47. In addition to the paper feed unit 200, manual paper feed is also possible, and a manual feed tray 51 for manual feed and a separation roller 52 for separating recording materials on the manual feed tray one by one toward the manual paper feed path 53 are also provided. It is provided on the side of the device. The registration roller 49 discharges only one recording material placed on the paper feed cassette 44 or the manual feed tray 51, and a secondary transfer nip portion located between the intermediate transfer body 10 and the secondary transfer means 22. Send to.

When the image forming unit 100 receives image information from the scanner unit 300, the image forming unit 100 forms a latent image on the photoconductor 40 by performing the laser writing or developing process as described above. The developer supplied to the developing sleeve 65 is pumped and held by a magnet inside the developing sleeve 65 to form a magnetic brush on the developing sleeve 65. Further, the toner image is transferred to the photosensitive member 40 by the developing bias voltage applied to the developing sleeve 65, and the electrostatic latent image on the photosensitive member 40 is visualized to form a toner image. A mechanism for uniformly applying fine particles having a function of preventing toner filming (not shown) to the photoconductor 40 is provided in contact with the photoconductor 40.
Next, one of the paper feed rollers 42 is operated to feed a recording material having a size corresponding to the toner image. Along with this, one of the support rollers 14, 15 and 16 is rotationally driven by the drive motor, the other two support rollers are driven to rotate, and the intermediate transfer member 10 is rotated and conveyed. At the same time, the photoreceptors 40Bk, 40Y, 40M, and 40C are rotated by the individual image forming units 18 to form Bk, Y, M, and C monochrome images on the photoreceptors 40Bk, 40Y, 40M, and 40C, respectively. . Then, along with the conveyance of the intermediate transfer body 10, the single color images are sequentially transferred to the primary transfer members 62Bk, 62Y, 62M, and 62C by applying current from the constant current power supplies 64Bk, 64Y, 64M, and 64C, respectively. Thus, a synthetic toner image is formed on the intermediate transfer member 10.
On the other hand, one of the paper feed rollers 42 of the paper feed unit 200 is selectively rotated, the recording material is fed out from one of the paper feed cassettes 44, separated one by one by the separation porter 45, and put into the paper feed path 46. Then, the conveying roller 47 guides the recording material to the paper feeding path 48 in the image forming unit 100, and the recording material is abutted against the registration roller 49 and stopped. Alternatively, the sheet feeding roller 50 is rotated to feed the recording material on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. Then, the registration roller 49 is rotated in time with the synthesized toner image on the intermediate transfer member 10, and the recording material is sent to the secondary transfer nip portion where the intermediate transfer member 10 and the secondary transfer roller 23 R are in contact with each other. The toner image is secondarily transferred by the influence of the secondary transfer electric field and contact pressure formed in the nip, and the toner image is recorded on the recording material. The recording material after the image transfer is fed to the fixing device 25 by the conveying belt 24 of the secondary transfer means, and the fixing device 25 fixes the toner image by applying pressure and heat by the pressure port roller 27. Thereafter, the paper is discharged onto a paper discharge tray 57 by a discharge port roller 56. On the other hand, the residual toner image that has not been transferred to the recording material by the secondary transfer is scraped off by the cleaning blade 17 to prepare for the next image forming process.

FIG. 2 is an enlarged schematic view showing the image forming unit 100 of the image forming apparatus of the present invention. FIG. 3 shows the relationship between the recording material and the intermediate transfer member as viewed from the direction perpendicular to the secondary transfer portion. Hereinafter, embodiments of each claim will be described with reference to FIGS.
In the image forming apparatus of the present invention, when a recording material having a width less than the maximum usable width is used at least once, the photosensitive member 40 to the intermediate transfer member 10 at a timing other than the time of image formation on the recording material. Enter the toner image on top.
After image formation using at least one small-size recording material is completed, writing light L is controlled by controlling a laser (LD) or LED (not shown) on the photosensitive member 40 at a timing after image formation, generally called a job end. To form an electrostatic latent image on the surface of the photoreceptor 40. Here, there are 40Bk, 40Y, 40M, and 40C as photoreceptors, and one or more of these are used. Of course, you may go to all four. Here, a case where only one photoconductor 40C is used will be described. The timing for forming the electrostatic latent image is not limited to the job end, and may be any time other than during the image formation, such as before the next image formation or before transition to the standby mode.
Subsequently, a developer is supplied from the developing sleeve 65C to the electrostatic latent image formed on the surface of the photoreceptor 40C, and the electrostatic latent image is visualized with toner (toner image). Further, the toner image is transferred to the intermediate transfer member 10 by applying a current from the constant current power source 64C to the primary transfer member 62C. Note that the length of the image formed in the circumferential direction of the photoconductor 40C is desirably equal to or larger than the circumferential length of the intermediate transfer body 10 in order to prevent filming with respect to the intermediate transfer body 10 without unevenness. The toner image held on the intermediate transfer member 10 is removed from the intermediate transfer member 10 by the cleaning blade 17 together with the fine particles that can be a seed of filming.

  Furthermore, the image forming apparatus of the present invention inputs the toner image input from the photoreceptor 40 to the intermediate transfer member 10 continuously or discontinuously over the maximum width. The electrostatic latent image formed on the surface of the photoconductor 40C is formed by applying the intermediate transfer member 10 over the entire width such as a solid image (full solid image) or a dot full shot image (1 by 1 image) over the maximum usable recording material width L1. The fine particle filming can be prevented by defining an image with a very high area ratio that can be substantially covered. Here, the expression “discontinuous” does not necessarily have to be a solid image of all solids, and halftone, for example, writing by LD at the time of forming a latent image may be a 1 by 1 or 2 by 2 image. Means that.

  In the image forming apparatus of the present invention, when the intermediate transfer member width L1 is the width L2 of the used recording material, the toner image input from the image carrier to the intermediate transfer member is transferred to the intermediate transfer member width L1. It is input continuously or discontinuously into a portion included in the recording medium and a portion other than the width L2 of the used recording material (a portion in L1 that does not overlap with L2). Therefore, the part that was covered by the small size recording material is where the filming of fine particles is difficult to occur and the toner is not input. Thus, by carrying out only on the outside of the small size recording material, it is possible to prevent the occurrence of the fine particle filming while saving the toner used for the fine particle removal.

  In the image forming apparatus of the present invention, the secondary transfer device can contact and separate from the intermediate transfer member. This separates the secondary transfer roller 23R from the intermediate transfer member 10 by driving a cam (not shown). The secondary transfer roller 23R can be freely contacted and separated by driving a cam. Therefore, during image formation (specifically, during secondary transfer to the recording material), the secondary transfer device (for example, secondary transfer roller) that is in contact with the intermediate transfer member is kept in contact with the secondary transfer device later. It is inefficient to clean the transfer device. Therefore, the secondary transfer device is not soiled by separating the secondary transfer device from the intermediate transfer body during toner input for removing fine particles.

In the image forming apparatus of the present invention, when there are a plurality of image carriers, at least one image carrier can be separated from the intermediate transfer member. Therefore, for example, when toner is input from the photoconductor 40C, if the other photoconductors 40Bk, 40Y, and 40M are to be separated, the intermediate transfer device 11 is rotated counterclockwise with the primary transfer roller 62C as a fulcrum. Can be separated.
For example, when there are a plurality of photoconductors 40 such as the four-tandem intermediate transfer system, toner input to the intermediate transfer member 10 may be performed from any photoconductor 40. The photosensitive member 40 that does not perform toner input rotates unnecessarily when it is in contact with the intermediate transfer member 10, and when the developing device is rotated in the same manner as the photosensitive member 40, the developer is not rotated. There is a concern about the deterioration, and when the driving of the developing device is stopped, there is a possibility that the deterioration of the wear of the photoconductor 40 at the developing portion may proceed. Therefore, deterioration can be prevented by making it possible to separate the photosensitive member 40 that does not perform toner input for the fine particles from the intermediate transfer member 10.

In the image forming apparatus of the present invention, the cleaning member can contact and separate from the intermediate transfer member. Therefore, a cleaning blade 17 (not shown) that can be brought into contact with and separated from the intermediate transfer member 10 is provided in addition to the cleaning blade 17 shown. The cleaning blade 17 is separated from the intermediate transfer member 10 during normal image formation, and is controlled to come into contact therewith. The toner collected by the cleaning blade 17 ′ is configured to be finally collected by the developing device 61 by a conveying means such as a conveying coil.
Assuming a case where a plurality of colors are mixed, it is desirable to collect them in the black developing device 61Bk where the mixed colors are hardly noticeable. The toner on the intermediate transfer member 10 can be returned to the developing device and reused without throwing away the input toner.

The image forming apparatus of the present invention performs toner input to the intermediate transfer member in a single color.
By making the cleaning member in contact with the intermediate transfer member contactable and separable, the means for removing toner to be removed from the intermediate transfer member is not limited to a dedicated cleaning member. By limiting one of the photoconductors 40 to which toner is input to, for example, the photoconductor 40C, it is not necessary to write or drive other photoconductors 40Bk, 40Y, and 40M, thereby reducing energy consumption. In particular, this can be done without deterioration of the photoreceptor and developer.

In the image forming apparatus of the present invention, the remaining toner is collected by the developing device using the developing device having the same color as the toner input to the intermediate transfer member. The color of the photoconductor 40 for inputting the toner and the developing device 61 for finally collecting the cleaned toner are the same. For example, when the toner input is designed by the photoconductor 40C, the collection destination is the developing device 61C. Thereby, mixing of other colors into the developing device 61C can be reduced to a minimum.
In the image forming apparatus of the present invention, black toner is used to input toner to the intermediate transfer member. By limiting the toner input and collection to black, even if a color other than black is slightly mixed with the collected toner due to some trouble (such as toner scattering), it is difficult for people to see it. There is an advantage that it does not become an abnormal image.

1 shows an entire image forming apparatus. 1 is an enlarged schematic diagram illustrating an image forming unit 100 of an image forming apparatus of the present invention. The relationship between the recording material and the intermediate transfer member is viewed from the direction perpendicular to the secondary transfer portion.

Explanation of symbols

4 Developing device 10 Intermediate transfer belt (intermediate transfer member)
18 Image forming means 21 Exposure device 25 Fixing device 40 Photosensitive member (latent image carrier)
22 Secondary transfer device 62 Primary transfer device 100 Copier main body 200 Paper feed table 300 Scanner 400 Automatic document feeder

Claims (10)

An image carrier that has a mechanism that can be repeatedly used by rotating and can carry a latent image, a charging device that charges the image carrier by bringing a charging member into contact with or close to the surface of the image carrier, and an image Between a latent image forming device that forms a latent image on a carrier, a developing device that develops toner by attaching toner to the latent image on the image carrier, and an intermediate transfer member that moves while contacting the image carrier. A primary transfer device that transfers a toner image formed on an image carrier by forming a transfer electric field onto an intermediate transfer member, and a toner image held on the intermediate transfer member on a recording material of various sizes. In the image forming apparatus having at least one or more next transfer devices,
In the image forming apparatus, when a recording material less than the width of the intermediate transfer member is used at least once, toner is transferred from the image carrier to the intermediate transfer member at a timing other than the time of image formation on the recording material. An image forming apparatus for inputting an image. 2. The image forming apparatus according to claim 1, wherein a toner image input from the image carrier to the intermediate transfer member is input continuously or discontinuously to the intermediate transfer member. When the intermediate transfer member width L1 is the width L2 of the used recording material, the toner image input from the image carrier to the intermediate transfer member is a portion included in the intermediate transfer member width L1, and 2. The image forming apparatus according to claim 1, wherein the recording material is input continuously or discontinuously into a portion other than the width L2 of the used recording material (a portion within L1 that does not overlap with L2). The image forming apparatus according to claim 1, wherein the secondary transfer device is capable of contacting and separating from the intermediate transfer member. 5. The image forming apparatus according to claim 1, wherein when there are a plurality of image carriers, at least one image carrier can be separated from the intermediate transfer member. The image forming apparatus according to claim 5, wherein the cleaning member is capable of contacting and separating from the intermediate transfer member. The image forming apparatus according to claim 1, wherein the toner remaining on the intermediate transfer member after the secondary transfer device that is in contact with or separated from the intermediate transfer member is collected by the developing device. The image forming apparatus according to claim 1, wherein toner is input to the intermediate transfer member in a single color. The image forming apparatus according to claim 7, wherein the residual toner is collected by the developing device using a developing device having the same color as the toner input to the intermediate transfer member. The image forming apparatus according to claim 8, wherein the toner is input to the intermediate transfer member with black toner.

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