Image forming device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an electrophotographic image forming apparatus such as a copying machine and a printer, and particularly, a toner image of a plurality of colors is superposed on an intermediate transfer body to be formed, and the toner image is collectively transferred to a transfer material to obtain a color image. The present invention relates to a type of image forming apparatus.

【0002】

[Conventional technology]

In an image forming apparatus for forming a color image by superimposing toner images of a plurality of colors, an intermediate transfer body 105 has been conventionally used for the purpose of obtaining a color image without color shift, as shown in FIG. Has been proposed.

【0003】

This image forming apparatus sequentially charges each color by the charging device 102 and the exposure means 103 based on the image information color-separated into four colors of magenta (M), cyan (C), yellow (Y), and black (K). Exposure and development are performed by the rotary developing devices 104a to 104c of the developing device 104 and the fixed developing device 104d, and toner images are sequentially formed on the photosensitive drum 101, and these are sequentially formed on the intermediate transfer member 105. After superimposing and transferring (primary transfer), the transfer roller 106 collectively transfers (secondary transfer) onto a transfer material 107 such as paper to obtain a full-color image on the transfer material 107. After that, the transfer material 107 is conveyed to the fixing device 112, and the toner is fixed.

【0004】

The toner remaining on the photosensitive drum 101 without being transferred during the primary transfer is scraped off by the cleaning blade 108, which is a cleaning member pressed against the photosensitive drum, and collected in the waste toner container 109.

【0005】

On the other hand, the toner remaining on the intermediate transfer body 105 without being transferred during the secondary transfer is scraped off by (1) the cleaning blade 110, which is a cleaning member pressed against the intermediate transfer body 105, and the waste toner container 111. Will be collected. Alternatively, (2) while applying a predetermined voltage to the intermediate transfer body 105 each time the secondary transfer is completed, the intermediate transfer body 105 is cleaned once or several times to remove the remaining toner on the intermediate transfer body 105. There is also a method of returning to the photosensitive drum 101 side, scraping it with a cleaning blade 108 arranged on the photosensitive drum 101, and collecting it in a waste toner container 109.

【0006】

[Problems to be Solved by the Invention]

However, in the cleaning method of the intermediate transfer body 105 of the above (1), since it is necessary to attach the waste toner container 111 for collecting the scraped toner to the large intermediate transfer body 105, the image forming apparatus becomes large and the user However, there is a problem that it takes time and effort to replace the waste toner container 111 at regular intervals.

【0007】

The cleaning method (2) above eliminates the need for the waste toner container 111 attached to the intermediate transfer body 105, so that there is an advantage that there is no troublesome replacement of the waste toner container 111, but every time the secondary transfer is completed. Since the cleaning rotation of the intermediate transfer member 105 is applied to the intermediate transfer body 105, there is a problem that the number of output sheets for a certain period of time is reduced during continuous image formation.

【0008】

An object of the present invention is that the toner remaining on the secondary transfer on the intermediate transfer body can be satisfactorily recovered, the decrease in the number of output sheets for a certain period of time during continuous image formation can be eliminated, and the toner is attached to the intermediate transfer body. It is an object of the present invention to provide an image forming apparatus that does not require a waste toner container, eliminates troublesome replacement by the user, and makes it possible to miniaturize the apparatus.

【0009】

[Means for solving problems]

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention forms a toner image on a rotating first image carrier, which is primary on the surface of the rotating second image carrier in contact with the first image carrier. In an image forming apparatus that repeats the transfer, forms a color image in which toner images of a plurality of colors are superposed on the second image carrier, and collectively transfers the color image onto the transfer material in a secondary manner. The surface of the second image carrier is composed of a first portion including an image forming region forming the color image and a second portion other than the other non-image region, and the second portion. A temporary recovery member that temporarily recovers the remaining toner from the secondary transfer from the second image carrier is arranged at a position on the downstream side of the secondary transfer site and upstream of the primary transfer site with respect to the rotation direction of the image carrier. The surface roughness of the first portion, the second portion, and the temporary recovery member of the second image carrier is set, and the surface roughness of the first portion of the second image carrier <temporary recovery member <second The surface materials of the first part, the second part, and the temporary recovery member of the image carrier are separated from each other so as to be related to the second part of the image carrier. The type is configured so that the relationship is such that the first site of the second image carrier> the temporary recovery member> the second site of the second image carrier, and the temporary recovery is performed after the start of the secondary transfer. At the same time that the member starts to abut on the first portion of the second image carrier, an electric field in the toner recovery direction is formed between the temporary recovery member and the second image carrier, and the second image carrier The remaining toner from the secondary transfer is collected on the temporary recovery member, and after the completion of the secondary transfer, an electric field is formed between the temporary recovery member and the second image carrier in the direction of discharging the toner. , The toner collected on the temporary recovery member is discharged to the second portion of the second image carrier, then the formation of the electric field in the toner discharge direction is stopped, and the discharged toner is discharged to the second image carrier and the second image carrier. The image forming apparatus is characterized in that it is returned to the first image carrier due to the potential difference between the image carriers 1 and is collected by a cleaning means arranged on the first image carrier.

【0010】

Another aspect of the present invention is to form a toner image on a rotating first image carrier and place it on the surface of a rotating second image carrier in contact with the first image carrier. In an image forming apparatus in which the next transfer is repeated to form a color image in which toner images of a plurality of colors are superimposed on the second image carrier, and the color images are collectively secondarily transferred onto the transfer material. The surface of the second image carrier is composed of a first portion including an image forming region forming the color image and a second portion other than the other non-image region, and the second portion. At a position on the downstream side of the secondary transfer site and upstream of the primary transfer site with respect to the rotation direction of the image carrier, a temporary recovery member for temporarily collecting the remaining toner of the secondary transfer from the second image carrier is installed. The first part and the second part of the second image carrier are electrically insulated from each other, and the first part and the second part of the second image carrier are arranged. Has separate voltage applying means, and after the start of the secondary transfer, the temporary recovery member starts to abut on the first portion of the second image carrier, and at the same time, the temporary recovery member and the second image An electric field is formed between the carrier and the carrier in the direction of collecting toner, and the remaining toner from the secondary transfer present at the first site of the second image carrier is recovered by the temporary recovery member, and temporarily after the completion of the secondary transfer. An electric field is formed between the recovery member and the second image carrier in the toner ejection direction, and the toner recovered by the temporary recovery member is ejected to the second portion of the second image carrier, and then in the toner ejection direction. The formation of the electric field is stopped, and the discharged toner is returned to the first image carrier due to the potential difference between the second image carrier and the first image carrier, and the cleaning disposed on the first image carrier is performed. It is an image forming apparatus characterized by collecting by means.

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, examples of the present invention will be described with reference to the accompanying drawings.

【0012】

Example 1 FIG. 1 is a schematic cross-sectional view showing an embodiment of the image forming apparatus of the present invention, and the image forming apparatus is a laser printer. This image forming apparatus is connected to a host device (not shown) such as a personal computer or a workstation, and receives image data via a video interface in response to a print request from the host device.

【0013】

Based on this image data, this image forming device sequentially uses image information that has been color-separated into four colors, yellow (Y), magenta (M), cyan (C), and black (K), as in the past, for each color. Toner images are sequentially formed on the photosensitive drum 101, which is the first image carrier, and they are sequentially superimposed on the intermediate transfer member 105, which is the second image carrier. After being transferred together (primary transfer), they are collectively transferred onto a transfer material 107 such as paper (secondary transfer) to obtain a full-color image on the transfer material 107.

【0014】

The developing device 104 includes three rotary developing devices 104a, 104b and 104c that are sequentially used by switching with respect to the photosensitive drum 101, and one fixed developing device 104d that is used at the installation position of the photosensitive drum 101. It has become. The rotary developers 104a, 104b and 104c contain yellow, magenta and cyan toners, respectively, and the fixed developer 104d contains black toners. In this way, by rotating the three developing devices 3a to 3c of the developing device 104, the outer diameter of the photosensitive drum 101 is compared with the case where four fixed developing devices are arranged along the periphery of the photosensitive drum 101. Can be made smaller. Further, since the black developer 104d, which generally consumes a large amount of toner, is used as a fixed developer, there is an advantage that the toner capacity of the black developer 104d can be increased.

【0015】

The photosensitive drum 101, which is the first image carrier, forms a photosensitive layer made of an organic photosensitive material on an aluminum cylinder having an outer diameter of 50 mm, and further improves toner peeling and prevents the photosensitive layer from being scraped. A surface protective layer is provided. The photosensitive drum 101 is rotationally driven in the direction of arrow A at a predetermined peripheral speed of 100 mm / sec.

【0016】

The surface of the photosensitive drum 101 is uniformly charged to about -600 V by the charging means 102. Next, scanning exposure is performed by the exposure means 103 whose ON / OFF control is controlled according to the image data of the first color yellow, and the electrostatic latent image of the first color is exposed on the photosensitive drum 1 at an exposure part potential of about -100V. It is formed. The electrostatic latent image of the first color is developed using the developer 104a containing the negatively charged yellow toner of the developing device 104, and is visualized as a yellow toner image. The yellow toner image formed on the photosensitive drum 101 is primarily transferred on the intermediate transfer body 105 as the second image carrier at its nip portion (pressure contact portion).

【0017】

The intermediate transfer body 105 forms a conductive elastic layer made of NBR rubber or the like in which carbon or the like is dispersed on an aluminum cylinder, and forms a releasable surface layer made of a urethane resin or the like in which fluororesin or the like is dispersed on the surface thereof. And the resistance value is 10⁵ ~10¹⁰It is about Ω cm and has an outer diameter of 191 mm. The intermediate transfer body 105 is pressed against the photosensitive drum 101 with a predetermined pressing force, and is rotationally driven in the direction of arrow B at a peripheral speed substantially equal to the peripheral speed of the photosensitive drum 101 of 100 mm / sec. At the time of this primary transfer, a voltage VItr = + 100V uniquely set in advance is applied to the intermediate transfer body 105, which has the opposite polarity to the charging polarity (minus) of the toner.

【0018】

The outer peripheral surface portion of the intermediate transfer body 105 includes a first portion G including an image forming region where the toner image is transferred, and a second portion H which is a non-image region where the other toner images are not transferred. It is divided into. In the case of an image forming apparatus that performs a developing operation by switching the developing devices 104a to 104c of a plurality of colors as in this embodiment, a region corresponding to a certain time for switching the developing devices is required on the photosensitive drum 101. That is the second part H above.

【0019】

The photosensitive drum 101, which has completed the primary transfer of the yellow toner image, scrapes off the toner remaining without being transferred by the cleaning blade 108 that is pressed against the photosensitive drum 101, and then is used for forming an image of the next color. The scraped toner is collected in the waste toner container 109.

【0020】

The same process as above is repeated for the remaining three colors of magenta, cyan, and black, and the toner images obtained by developing each latent image with the developers 104b, 104c, and 104d of the developing device 104 are used as an intermediate transfer product. By superimposing on the 105 and performing the primary transfer, a color image in which four color toner images of yellow, magenta, cyan, and black are laminated on the intermediate transfer body 105 is formed.

【0021】

The four-color toner images are collectively transferred to the surface of the transfer material 107 conveyed from the paper feed unit at the nip portion (pressure contact portion) between the intermediate transfer body 105 and the transfer roller 106 as the transfer means. (Secondary transcription). The transfer roller 106 can be brought into contact with and detached from the intermediate transfer body 105, and at the time of transfer, the transfer roller 106 is pressed against the intermediate transfer body 105 at a predetermined timing at a peripheral speed substantially equal to the peripheral speed of the intermediate transfer body 105. It is rotated. At the time of secondary transfer, a voltage VIItr = + 1000V uniquely set in advance is applied to the transfer roller 106, which has the opposite polarity to the charging polarity of the toner.

【0022】

The transfer material 107 to which the four-color toner image is secondarily transferred is then conveyed to the fixing device 112, where the toner image is mixed and permanently fixed to the transfer material 107, and then the image forming device is released from the paper ejection unit. It is discharged to the outside of the machine and a desired color print image is obtained.

【0023】

According to the present invention, the toner remaining on the intermediate transfer body 105 that is not transferred during the secondary transfer is temporarily recovered by the temporary recovery member 120 (recovery operation), and then , The recovered toner is discharged onto the non-image portion on the intermediate transfer body 105, then returned to the photosensitive drum 101 side, scraped off by the cleaning blade 108 disposed on the photosensitive drum 101, and the waste toner container 109 is used. It is to be collected in (cleaning operation).

【0024】

According to this embodiment, the toner charge control member 122 is provided between the secondary transfer unit and the temporary recovery member 120. Before performing the above recovery operation, the toner charge control member 122 discharges the secondary transfer residual toner on the intermediate transfer body 105 so that the polarity of the secondary transfer residual toner is opposite to the charge polarity. Charge control is performed so that the toner is aligned positively and the toner holds a certain amount of charge or more.

【0025】

In this embodiment, the temporary recovery member 120 is 10⁷ A sponge-like elastic body made of conductive NBR rubber or the like whose resistance value is adjusted to about Ω cm is formed in a roll shape around the shaft, and a fluororesin for obtaining a predetermined releasability is dispersed on the surface thereof. It is composed of a roller with an outer diameter of 20 mm, which is covered with a resistance film, and has a surface roughness Rz of about 5 μm. The temporary recovery member 120 is rotationally driven in the forward direction of arrow C at a peripheral speed of 150% with respect to the intermediate transfer body 105, and a nip width of about 2 to 3 mm is formed between the temporary recovery member 120 and the intermediate transfer body 105. It is pressure-welded by the pressing force of.

【0026】

Hereinafter, the operation of collecting the secondary transfer residual toner by the temporary collection member 120 and the cleaning operation of the temporary collection member 120 or less will be described. FIG. 2 is a schematic diagram showing a control method for the collection operation and the cleaning operation.

【0027】

The first region G on the intermediate transfer body 105, that is, the region G in FIG. 2, is an image region (hence, a transfer material) on which four color toner images on the intermediate transfer body 105 are laminated when forming n continuous images. It is a region that comes into contact with 107, and is also a region where the residual toner for secondary transfer remains). The other second portion H on the intermediate transfer body 105, that is, the region H in FIG. 2, is an intermediate between image regions on the intermediate transfer body 105 at the time of forming n continuous images, that is, between papers. It is a non-image area on the transfer body 105.

【0028】

In this example, the surface roughness at the two sites G and H on the intermediate transfer body 105 is different. Considering the transferability of the toner to the transfer material, the surface roughness of the first portion G is preferably Rz 5 μm from the viewpoint of improving the secondary transfer efficiency, and more preferably Rz 1 μm. .. The surface roughness of the second portion H is preferably Rz 10 μm in consideration of the ejection of toner from the temporary recovery member 120 to the region H. Specifically, in this embodiment, the surface roughness of the first portion G is Rz 1 μm, and the surface roughness of the second portion H is Rz 10 μm.

【0029】

When the secondary transfer is started during continuous image formation, as shown in FIG. 2, the temporary recovery member 120 located downstream from the secondary transfer site is moved forward to the intermediate transfer body 105 with respect to the intermediate transfer body 105. While being driven to rotate, it contacts (ON) between the regions I including the region in which the secondary transfer residual toner (previously positively controlled by the toner charge control member 122) exists. Simultaneously with the contact of the temporary recovery member 102, the potential difference between the recovery member 120 and the intermediate transfer body 105 (potential VItr during continuous image formation) with the positively controlled secondary transfer residual toner in the opposite polarity direction. A DC bias of opposite polarity (recovery potential VCc = -100V) is applied so that the secondary transfer residual toner is recovered by the recovery member 120.

【0030】

In this embodiment, a peripheral speed difference is provided between the rotations of the intermediate transfer member 105 and the temporary recovery member 120, and the surface roughness (1 μm) of the region G on the intermediate transfer member 105 is set to the surface roughness (5 μm) of the recovery member 120. Since it is configured to be smaller than the recovery member 120, it is easy to peel off the secondary transfer residual toner on the intermediate transfer body 105 by rubbing between the recovery member 120 and the intermediate transfer body 105. Therefore, the recovery member The secondary transfer residual toner can be easily electrostatically transferred to the recovery member 120 and recovered by the electric field due to the reverse potential difference between the 120 and the intermediate transfer body 105.

【0031】

After the secondary transfer residual toner is collected on the temporary recovery member 120, immediately after the recovery (that is, immediately after the first portion G passes through the temporary recovery member 120), the bias applied to the recovery member 120 is switched to switch the recovery member. Let the potential VC of 120 be the cleaning potential VCc1 = + 200V. As a result, an electric field is applied to the potential VItr = + 100V of the intermediate transfer body 105 in the direction opposite to that at the time of recovery (the direction in which the toner having a positive charge is transferred to the intermediate transfer body 105), so that the recovery member 120 The recovered toner recovered in the recovery is discharged to the second portion H of the intermediate transfer body 105, and the recovery member 120 is cleaned. The cleaning bias applied to the temporary recovery member 120 is applied immediately before the ejection of the toner to the second portion H of the intermediate transfer member 105 is completed (that is, immediately before the second portion H finishes passing through the temporary recovery member 120). , The recovery member 120 is separated from the intermediate transfer body 105 and then cut. That is, the cleaning operation is performed in the region indicated by J in FIG. 2 of the intermediate transfer body 105, and the recovered toner is transferred from the temporary recovery member 120 to the region J on the intermediate transfer body 105.

【0032】

At this time, in this embodiment, since the surface roughness of the region H, which is the second portion on the intermediate transfer body 105, is configured to be larger than the surface roughness of the temporary recovery member 120, the intermediate transfer body The recovery toner on the recovery member 120 can be easily peeled off by rubbing between the recovery member 120 and the recovery member 120. Therefore, an electric field in the direction opposite to that at the time of recovery between the recovery member 120 and the intermediate transfer body 105 causes The recovered toner can be easily electrostatically transferred to the intermediate transfer body 105 and discharged to clean the recovered member 120 satisfactorily.

【0033】

In this way, the toner discharged into the region J on the intermediate transfer body 105 is the statically eliminated photosensitive layer (surface potential of about 0 V) of the photosensitive drum 101 at the nip portion between the photosensitive drum 101 and the intermediate transfer body 105. It is returned to the photosensitive drum 101 due to the potential difference (100V) from the intermediate transfer body 105 (potential VI = + 100V). The toner returned to the photosensitive drum 101 is cleaned by a cleaning blade 108 disposed on the photosensitive drum 101 and collected in a waste toner container 109.

【0034】

In the image forming apparatus of this embodiment, by repeating the above control, a continuous image forming operation including a toner recovery and cleaning operation is performed for each print. In this example, when a continuous image formation experiment was carried out under the above control, no abnormal image was observed due to poor recovery of the secondary transfer residual toner by the temporary recovery member 120 or poor cleaning of the recovery member 120.

【0035】

In the above, when the secondary transfer residual toner on the intermediate transfer body 105 is collected by the temporary collection member 120, when the recovery toner is discharged from the collection member 120 to the intermediate transfer body 105, and when the discharge toner is discharged from the intermediate transfer body 105. Each potential at the time of returning to the photosensitive drum 101 and the potential difference from each intermediate transfer body 105 should be appropriately set in consideration of the resistance values of the intermediate transfer body 105 and the recovery member 120, the amount of toner charge, and the like. However, it is not limited to this embodiment.

【0036】

Further, a case has been described in which, at the time of forming a continuous image, the secondary transfer residual toner is collected on the temporary recovery member 120 for each print, and the recovery member 120 is cleaned immediately after the recovery operation. Not limited to this, for all prints of a plurality of prints or a certain number of prints, only the operation of collecting the residual toner of the secondary transfer is continuously performed, and after the toner is accumulated in the recovery member 120, all the prints or a certain number of prints are performed. It is also possible to perform a cleaning operation of the recovery member 120 at the end of printing.

【0037】

The material of the temporary recovery member 120 is an elastic body made of conductive NBR rubber used in this example, as well as a volume resistivity of 10 made of urethane, EPDM, silicone rubber, or the like.¹⁰A conductive elastic body adjusted to Ω cm or less, or a foam thereof may be used. On the surface of these elastic bodies and foams, for example, volume resistivity 10¹⁰~10¹⁴It is a high resistance layer of about Ω cm, and its surface layer has almost the same releasability as the intermediate transfer body 105 with respect to toner, and is rougher than the surface of the first portion G of the intermediate transfer body 105, and is the second. A high-resistance film having a surface roughness smoother than the surface of the site H can be formed to a thickness of 1 to 100 μm.

【0038】

A conductive brush roller can also be used as the temporary recovery member 120. The conductive brush roller has a volume resistivity of 10 around a highly rigid conductive substrate such as metal or an elastic conductive substrate made of conductive rubber or the like.¹⁰Conductive fibers of about Ω cm or less are planted, and as the conductive fibers, fibers such as rayon, polyamide, acrylic, and tetrafluoropolyethylene that have been subjected to conductive treatment such as carbon dispersion can be used.

【0039】

The rotation direction of the temporary recovery member 120 may be a direction that serves as a counter with respect to the intermediate transfer body 105 opposite to that of the embodiment. In this case, a larger peripheral speed difference is provided to the recovery member 120. The recovery performance of the secondary transfer residual toner and the discharge performance of the recovered toner to the intermediate transfer body 105 can be adjusted. The rotation and peripheral speed of the temporary recovery member 120 can also be appropriately set so as to optimize the recovery operation and the cleaning operation in consideration of the material, surface roughness, etc. of the intermediate transfer body 105 and the recovery member 120. ..

【0040】

The toner preferably has advantages such as excellent transferability, little secondary transfer residue, easy electrostatic recovery by the temporary recovery member 120, and easy discharge from the recovery member 120 after recovery, for example, a sphere. Examples of toner have a smooth surface and a shape. Specifically, a spherical toner having a shape coefficient SF-1 of 10 to 180 and SF-2 of 100 to 140 is preferable.

【0041】

In the image forming apparatus of this embodiment, as described above, the temporary recovery member 120 recovers the residual toner of the secondary transfer and the recovery member 120 is cleaned. Therefore, the waste toner container of the intermediate transfer member 105 is eliminated. Therefore, the time-consuming work of replacing the waste toner container by the user can be omitted, and the image forming apparatus can be miniaturized. Further, when forming a continuous image, it is possible to eliminate the cleaning rotation of the intermediate transfer member 105 at the end of printing one sheet, and it is possible to increase the number of print outputs (throughput; ppm) in a fixed time.

【0042】

For example, in an image forming apparatus having a rotary developer similar to that of the present embodiment, when an intermediate transfer material having the same outer diameter of 191 mm is used under the condition of rotating at the same peripheral speed of 100 mm / sec, one conventional image is used. In the method in which the intermediate transfer body is cleaned and rotated every time the printing is completed, the printing throughput is 2 ppm for a full-color image and 5 ppm for a mono-color image, whereas in the image forming apparatus of this embodiment, the printing throughput is 2 ppm, respectively. Increased to 2.5ppm and 10ppm.

【0043】

Example 2 The feature of this example is that in the image forming apparatus of Example 1 shown in FIG. 1, the first part G and the second part H on the intermediate transfer body 105 are formed of different materials. In Example 1, the first portion G and the second portion H were formed to have the same material but different surface roughness. Since the other configurations of the image forming apparatus of this embodiment are basically the same as those of the first embodiment, the description of the image forming apparatus and its respective parts is omitted by referring to the explanations of FIGS. 1 and 1. To do.

【0044】

In this embodiment, in the image forming apparatus of FIG. 1, when the temporary recovery member 120 recovers the secondary transfer residual toner on the intermediate transfer member 120, the first transfer residue toner is present on the intermediate transfer body 105. In order to improve the peelability of the surface of the site G and improve the recovery efficiency of the secondary transfer residual toner, the surface of the first site G was formed to have a peelability higher than that of the recovery member 120. Further, in order to facilitate the discharge of the recovered toner to the intermediate transfer body 105 during the cleaning operation of the temporary recovery member 120, the surface of the recovery member 120 is covered with a second region on the intermediate transfer body 105 on which the recovery toner is discharged. It was formed so that the peelability was higher than that of the surface region of H. That is, the order of high and low peelability is configured so that the first site G> the temporary recovery member> the second site H.

【0045】

According to this embodiment, specifically, the number of parts of the fluororesin PTFE dispersed in the urethane resin forming the surface layer of the intermediate transfer body 105 is 400 parts in the first portion G with respect to 100 parts of the urethane resin. By setting the number of parts in the second part H to 100, the order of releasability of the first part G> temporary recovery member> the second part H was realized. In addition, the above-mentioned order of peelability can be obtained by forming the surface layer of the intermediate transfer material 105 with different types of fluororesins, changing the amount of carbon and other fillers dispersed in the surface layer, and the like.

【0046】

In this embodiment, according to the above configuration, the temporary recovery member 120 recovers the secondary transfer residual toner on the intermediate transfer body 105, and the recovery member 120 or less is cleaned. The conditions such as the recovery bias and the cleaning bias applied to the temporary recovery member 120 were the same as in Example 1.

【0047】

As a result, the secondary transfer residual toner on the region of the first portion G on the intermediate transfer body 105 is higher due to the difference in releasability when the temporary recovery member 120 and the first portion G are rubbed. With the recovery efficiency, it was possible to recover to the side of the recovery member 120. Further, the recovered toner collected by the temporary recovery member 120 is discharged with high discharge efficiency due to the difference in releasability when the recovery member 120 and the second portion H on the intermediate transfer body 105 are rubbed. It was possible to spit it out to the side of the site H, and the recovery member 120 could be cleaned cleanly.

【0048】

Further, as in Example 1, when a continuous image formation experiment was carried out, a ghost image due to the secondary transfer residual toner remaining on the intermediate transfer member 105 due to poor recovery to the temporary recovery member 120 and poor cleaning of the recovery member 120 were performed. No abnormal images were observed due to such factors.

【0049】

Example 3 FIG. 3 is a schematic cross-sectional view showing still another embodiment of the image forming apparatus of the present invention. The feature of this embodiment is that the first site G and the second site H on the intermediate transfer body 105 are electrically insulated so that a bias different from that of the site G can be applied to the site H. .. Other configurations of the image forming apparatus of this embodiment are basically the same as those of the image forming apparatus of FIG. In FIG. 3, the parts common to FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

【0050】

In this embodiment, as shown in FIG. 3, the first part G and the second part G are formed by inserting an insulating member K between the first part G and the second part H on the intermediate transfer body 105. The parts of H were electrically insulated from each other. Similar to Example 1, the secondary transfer residual toner is recovered by the temporary recovery member 120 in the region of the first portion G that is insulated from each other, and is also recovered in the region of the second portion H. The recovered toner is discharged from the member 120.

【0051】

Hereinafter, the control method of the collection operation and the cleaning operation in this embodiment will be described with reference to FIG.

【0052】

During continuous image formation, as shown in FIG. 4, the potential VIG = + 100V is applied to the first site G on the intermediate transfer body 105, and the potential V1H = -200V is applied to the second site H. There is. When the secondary transfer is started, the temporary recovery member 120 located downstream from the secondary transfer site is brought into contact with the intermediate transfer body 105 only during the region I including the region where the residual toner of the secondary transfer remains (). ON). The charge polarity and the amount of the charge thereof of the secondary transfer residual toner on the intermediate transfer body 105 are controlled by the toner charge control member 122 before the recovery operation by the temporary recovery member 120 is performed, as in the first embodiment. In the embodiment, the charge polarity is controlled to be opposite to that of the first embodiment, that is, to be negative, which is the same polarity as the original charge polarity of the toner. At the same time as the contact of the temporary recovery member 102, the polarity of the recovery member 120 is negatively controlled with respect to the potential VIG = + 100V applied to the first portion G on the intermediate transfer body 105. A DC bias (recovery voltage VCc = + 200V) having the opposite polarity to the transfer residual toner is applied, and the secondary transfer residual toner is recovered by the recovery member 120.

【0053】

After the toner remaining in the secondary transfer is collected on the temporary recovery member 120, immediately after the recovery (immediately after the first portion G passes through the temporary recovery member 120), the bias applied to the recovery member 120 is switched to recover the recovery member. Let the potential VC of 120 be the cleaning potential VCc1 = -400V. At this time, the region on the intermediate transfer body 104 in contact with the recovery member 120 shifts from the first site G to the second site H, and the potential VIH = -200V of the second region H is opposite to that at the time of recovery. Since an electric field is applied in the direction of (the direction in which the toner having a negative charge is transferred to the intermediate transfer body 105), the toner having the negative polarity transferred to the recovery member 120 is the second portion of the intermediate transfer body 105. It is discharged into the region of H, and the recovery member 120 is cleaned.

【0054】

The cleaning bias applied to the temporary recovery member 120 is cut after separating the recovery member 120 from the intermediate transfer body 105 immediately before the discharge of the toner to the second portion H is completed. Therefore, the cleaning operation is performed in the region indicated by J in FIG. 4 of the intermediate transfer member 105, and the recovered toner of the temporary recovery member 120 is transferred to the region J on the intermediate transfer body 105.

【0055】

The toner discharged into the region J on the intermediate transfer body 105 is the statically eliminated photosensitive layer (surface potential of about 0 V) of the photosensitive drum 101 and the intermediate transfer body 105 (at the nip portion between the photosensitive drum 101 and the intermediate transfer body 105). It is returned to the photosensitive drum 101 due to the potential difference (200V) from the potential VIH = -200V). The toner returned to the photosensitive drum 101 is cleaned by the cleaning blade 108 of the photosensitive drum 101 and collected in the waste toner container 109.

【0056】

By repeating the above control, a continuous image forming operation including a toner collection and cleaning operation is performed for each print. In this example, when a continuous image formation experiment was carried out under the above control, no abnormal image was observed due to recovery of the toner remaining in the secondary transfer, poor cleaning, or the like.

【0057】

Since this embodiment is configured as described above, it is possible to recover the secondary transfer residual toner on the intermediate transfer body 105 without reversing the polarity, and similarly, the waste toner container of the intermediate transfer body 105 is eliminated. Therefore, the time-consuming work of replacing the waste toner container by the user can be omitted, and the image forming apparatus can be miniaturized. Further, when forming a continuous image, it is possible to eliminate the cleaning rotation of the intermediate transfer body for each print, and it is possible to increase the print throughput in a certain period of time.

【0058】

[Effect of the invention]

As described above, in the image forming apparatus of the present invention, the surface of the intermediate transfer body, which is the second image carrier on which the toner images of a plurality of colors formed on the first image carrier are transferred, is imaged. The first part including the formation region and the second part which is the other non-image area are divided, and the relationship between these and the temporary recovery member is described in terms of surface roughness of the second image-bearing body. Part 1 <Temporary recovery member <The relationship between the second part of the second image carrier, or the surface material, the releasability of the surface, is the first of the second image carrier. Since the relationship is such that the part> the temporary recovery member> the second part of the second image carrier, the secondary transfer in which the toner images of multiple colors on the intermediate transfer body are collectively transferred onto the transfer material. By forming an electric field in the toner recovery direction between the temporary recovery member and the intermediate transfer member, the secondary transfer residual toner can be satisfactorily recovered to the temporary recovery member, and the temporary recovery member and the intermediate transfer body can be recovered. By forming an electric field in the direction of discharging the toner between the two, the recovered toner on the temporary recovery member can be satisfactorily discharged to the intermediate transfer body. Therefore, the waste toner container attached to the intermediate transfer body becomes unnecessary, the troublesome user's troublesome replacement of the waste toner container can be saved, the device can be miniaturized, and a certain period of time during continuous image formation can be achieved. The number of output sheets can be increased.

【0059】

Further, by electrically insulating the first part and the second part of the intermediate transfer body from each other, it becomes possible to apply different voltages to each part during image formation, and the charging polarity of the toner is increased. It is possible to temporarily recover the secondary transfer residual toner from the intermediate transfer body and discharge the recovered toner to the intermediate transfer body without reversing the original charge polarity. Similarly, it is attached to the intermediate transfer body. It has the effect of eliminating the need for waste toner containers.

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing which shows the schematic structure of the image forming apparatus in one Example of this invention.

[Figure 2]

It is a schematic diagram which shows the control method of the recovery operation of the secondary transfer residual toner by the temporary recovery member installed in the apparatus of FIG. 1 and the cleaning operation below the temporary recovery member.

[Fig. 3]

It is sectional drawing which shows the schematic structure of the image forming apparatus in another Example of this invention.

[Fig. 4]

It is a schematic diagram which shows the control method of the recovery operation of the secondary transfer residual toner by the temporary recovery member installed in the apparatus of FIG. 3 and the cleaning operation below the temporary recovery member.

[Fig. 5]

It is sectional drawing which shows the schematic structure of the conventional image forming apparatus.

[Explanation of symbols]

101 Photosensitive drum 104 Developer 105 Intermediate transcript 108 Cleaning blade 109 Waste toner container 120 Temporary recovery member 122 Toner charge control member