JP2012163799A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device that suppresses variations of a contact angle caused by variations of the amount of lubricant on an intermediate transfer body to prevent cleaning troubles of the intermediate transfer body by effectively removing excessively applied lubricant through the transition from a plurality of image carriers to the intermediate transfer body.SOLUTION: An image formation device includes: an intermediate transfer body; a plurality of image formation parts in which there are provided an image carrier, lubricant application means for applying lubricant onto at least a non-image formation area of the image carrier, a development apparatus for forming a toner image on the image carrier, and primary transfer means for transferring the toner image on the image carrier onto the intermediate transfer body, respectively; a cleaning member for cleaning the residual toner on the intermediate transfer body after secondary transfer; a lubricant removal member that is arranged at a position between two image formation parts adjacent in the direction of movement of the intermediate transfer body so as to come into contact with and separate from the intermediate transfer body and removes the lubricant thereon; and control means for contacting and separating the lubricant removal member and the intermediate transfer body.

Description

  The present invention relates to an image forming apparatus.

  As a conventional image forming apparatus using an electrophotographic method, each time a toner image of a different color is sequentially formed on a plurality of image carriers on which a lubricant is applied by a lubricant applying means, a toner image of each color An intermediate transfer type image forming apparatus is known in which a primary transfer image is transferred onto a transfer material after primary transfer is performed by transferring the toner image onto an intermediate transfer member. (For example, refer to Patent Document 1).

  In such an image forming apparatus, if the image forming process of forming an image while applying a lubricant to the image carrier is repeated many times, the lubricant applied to the image carrier moves to the intermediate transfer member and accumulates. As a result, the surface energy of the intermediate transfer member is lowered, so that the difference between the surface energy of the image carrier and the surface energy of the intermediate transfer member is reversed or reduced, and the transferability is lowered.

  Therefore, in Patent Document 1, the above problem is solved by providing a lubricant removing member made of a magnetic brush for removing the lubricant on the intermediate transfer member.

JP 2005-352009 A

  In the above-described intermediate transfer method, a toner image is formed on the intermediate transfer member, and thus a cleaning device that cleans residual toner on the intermediate transfer member after transferring the toner image to a transfer material is required.

  In the technique disclosed in Patent Document 1, since the lubricant removing member is arranged downstream of the cleaning device and upstream of the primary transfer means for the first color with respect to the moving direction of the intermediate transfer body, The lubricant applied to the intermediate transfer member from the image bearing member cannot be removed effectively, and the surface energy of the intermediate transfer member changes due to the increase or decrease in the amount of lubricant applied. It has been found that a cleaning failure occurs when the changes.

  That is, the tip of the cleaning blade that is in pressure contact with the surface of the intermediate transfer member is wound in the direction of movement of the surface of the intermediate transfer member, and the phenomenon that the tip is turned up and turned in the direction of movement (the pulling phenomenon) occurs. The toner adhering to the body surface slips between the leading edge of the cleaning blade and the intermediate transfer body surface, resulting in poor cleaning.

  In particular, in the technique disclosed in Patent Document 1, this lubricant is applied to almost the entire surface including the non-image forming area on the peripheral surface of the image carrier by the lubricant application means always in contact with the image carrier. Will be.

  In an electrophotographic image forming apparatus, a developer (toner for one-component development, toner and carrier for two-component development) is carried on an image carrier on which an electrostatic latent image is formed. The developer carrying member (developing sleeve) is relatively moved to develop the electrostatic latent image on the image carrying member.

  The lubricant applied to the image forming area of the image carrier is then carried by the developer that moves while contacting the image carrier as the developer carrier rotates, and is taken into the developing device. The amount of lubricant on the carrier decreases, and the amount transferred to the intermediate transfer member is small.

  However, since the developer carrier normally stops rotating when it passes through the non-image forming area of the image carrier, the lubricant is applied to the non-image forming area of the image carrier when the lubricant is applied to the non-image forming area of the image carrier. The amount remaining on the body as it is and transferred to the intermediate transfer body is increased, and as a result, the influence on the cleaning failure is increased. For this reason, it is important to surely remove the lubricant applied to the non-image forming area of the image carrier and transferred to the non-image forming area of the intermediate transfer member.

  The present invention suppresses variation in contact angle due to variation in the amount of lubricant on the intermediate transfer member by effectively removing the excessively applied lubricant from the plurality of image carriers to the intermediate transfer member. An object of the present invention is to provide an image forming apparatus capable of preventing poor cleaning of the intermediate transfer member.

The object is achieved by the following invention.
1.
An intermediate transfer member;
An image carrier, a lubricant applying means for applying a lubricant to at least a non-image forming area of the image carrier, a developing device for forming a toner image on the image carrier, and a toner image on the image carrier. A plurality of image forming units each provided with a primary transfer means for transferring the image to the intermediate transfer member;
A cleaning member for cleaning residual toner on the intermediate transfer member after the secondary transfer;
A lubricant removing member that is disposed in a position between the two image forming units adjacent to each other in the moving direction of the intermediate transfer body so as to be able to contact with and separate from the intermediate transfer body, and removes the lubricant on the intermediate transfer body;
Control means for contacting and separating the lubricant removing member and the intermediate transfer member;
An image forming apparatus comprising:
2.
When the non-image forming region on the intermediate transfer member passes through the position of the lubricant removing member, the control unit brings the lubricant removing member and the intermediate transfer member into contact with each other on the intermediate transfer member. 2. The image forming apparatus according to 1, wherein the lubricant is removed.
3.
The control means separates the lubricant removing member and the intermediate transfer member when the image forming area on the intermediate transfer member passes the position of the lubricant removing member. The image forming apparatus described in 1.
4).
The control means is configured to control the lubricant removing member and the intermediate transfer member based on the rotation state of the developer carrying member of the developing device of the image forming unit located upstream of the lubricant removing member in the moving direction of the intermediate transfer member. The image forming apparatus according to any one of claims 1 to 3, wherein the body is brought into contact with and separated from the body.
5.
The apparatus further comprises a lubricant removing member disposed upstream of the cleaning member and downstream of the most downstream image forming unit among the plurality of image forming units with respect to the moving direction of the intermediate transfer member. The image forming apparatus according to any one of 1 to 4.
6).
The control unit changes a contact condition between the lubricant removing member and the intermediate transfer member based on an operation history based on an initial state of the cleaning member. 2. The image forming apparatus according to item 1.
7).
The control unit changes a contact condition between the lubricant removing member and the intermediate transfer body based on at least one of temperature and humidity of an atmosphere in which the image forming apparatus is installed. The image forming apparatus according to any one of 6.
8).
The image forming apparatus according to claim 6 or 7, wherein the contact condition includes at least one of a contact time and a contact pressure.
9.
The lubricant removing member is composed of a sheet-like member,
The image forming apparatus according to claim 6 or 7, wherein the contact condition includes at least one of a contact time, a contact pressure, and a contact angle.

  According to the present invention, the contact angle varies due to variations in the amount of lubricant on the intermediate transfer member by effectively removing the excessively applied lubricant from the plurality of image carriers to the intermediate transfer member. Therefore, it is possible to provide an image forming apparatus that can suppress the cleaning of the intermediate transfer member and prevent poor cleaning of the intermediate transfer member.

1 is a diagram illustrating a color image forming apparatus according to an embodiment of the present invention. It is a figure which shows the structure of an image formation part and a lubricant removal member. It is a figure which shows an example of the time chart of a color image formation process. FIG. 4 is a diagram illustrating an example of timings of contact and separation between an image forming region and a non-image forming region on an intermediate transfer member and a lubricant removing member. It is a block diagram which shows the control structure of contact | abutting and separation | spacing control of a lubricant removal member.

<Image forming apparatus>
FIG. 1 is a diagram showing a color image forming apparatus according to an embodiment of the present invention.

  This color image forming apparatus is called a tandem color image forming apparatus, and includes four image forming units 10Y, 10M, 10C, and 10K, lubricant removing members 75Y, 75M, 75C, and 75K, and an intermediate transfer unit 7. A fixing device 24, a cleaning device 60, and a control unit 50 for controlling the operation of each unit. A document image reading device SC is disposed above the color image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging device 2Y, an exposure device 3Y, a developing device 4Y, a primary transfer unit 5Y, a lubricant applying unit 30Y, and a cleaning device 6Y arranged around the image carrier 1Y. Have The image forming unit 10M that forms a magenta image includes an image carrier 1M, a charging device 2M, an exposure device 3M, a developing device 4M, a primary transfer unit 5M, a lubricant applying unit 30M, and a cleaning device 6M. The image forming unit 10C that forms a cyan image includes an image carrier 1C, a charging device 2C, an exposure device 3C, a developing device 4C, a primary transfer unit 5C, a lubricant applying unit 30C, and a cleaning device 6C. The image forming unit 10K that forms a black image includes an image carrier 1K, a charging device 2K, an exposure device 3K, a developing device 4K, a primary transfer unit 5K, a lubricant applying unit 30K, and a cleaning device 6K.

  The intermediate transfer unit 7 includes a semiconductive endless belt-like intermediate transfer body 70 that is supported by a plurality of rollers 71 to 74 and circulates, and a secondary transfer unit 5A.

  The lubricant removing members 75Y, 75M, and 75C are provided between two adjacent image forming units among the four image forming units 10Y, 10M, 10C, and 10K arranged along the moving direction of the intermediate transfer body 70. At this position, the intermediate transfer member is disposed so as to be able to contact and separate, and the lubricant on the intermediate transfer member 70 is removed. The lubricant removing member 75K is disposed downstream of 10K and upstream of the secondary transfer unit 5A so as to be able to contact and separate from the intermediate transfer body 70, and removes the lubricant on the intermediate transfer body 70.

  The images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred and superimposed on the intermediate transfer body 70 by the primary transfer units 5Y, 5M, 5C, and 5K, and are combined. A color image is formed. The transfer material P accommodated in the paper feed cassette 20 is fed by the paper feed means 21 and is conveyed to the secondary transfer means 5A through the plurality of intermediate rollers 22A, 22B, 22C, 22D and the registration rollers 23. A color image is collectively transferred onto the transfer material P. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing device 24, conveyed to a paper discharge roller 25, and discharged onto a paper discharge tray 26 outside the apparatus. The secondary transfer means 5A includes a transfer roller 5AR and a transfer power supply 5AE that are made of semiconductive rubber and presses the transfer material P against the intermediate transfer body 70. The transfer power supply 5AE applies a voltage having a polarity opposite to the charge of the toner to the transfer roller 5AR. Apply to.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer means 5A, the intermediate transfer member 70 passes through the cleaning device 60 and the residual toner is removed. The cleaning device 60 scrapes off the toner on the intermediate transfer body 70 with a cleaning blade (cleaning member) 61 made of rubber such as urethane rubber.

  During the image forming process, the primary transfer unit 5K is always in pressure contact with the image carrier 1K. The other primary transfer units 5Y, 5M, and 5C are in pressure contact with the corresponding image carriers 1Y, 1M, and 1C, respectively, only during color image formation.

  FIG. 2 shows the configuration of the image forming units 10Y, 10M, 10C, and 10K. Since the image forming units 10Y, 10M, 10C, and 10K have the same configuration, the reference numeral YMCK is omitted in FIG.

  Around the image carrier 1, a charging device 2, an exposure device 3, a developing device 4, a primary transfer unit 5, a lubricant application unit 30 and a cleaning device 6 are arranged.

  As the image carrier 1, an OPC photoreceptor is preferably used, and a negatively chargeable OPC photoreceptor is particularly preferred.

  The exposure device 3 is preferably an exposure device that scans and exposes the image carrier 1 with a light beam, and a laser, an LED array, or the like is preferably used. The exposure device 3 forms a dot image on the image carrier 1 by exposure based on the image data.

  The developing device 4 is a developing sleeve (made of cylindrical non-magnetic stainless steel or aluminum, etc., which rotates at a predetermined distance from the circumferential surface of the image carrier 1 and rotates in a direction opposite to the rotation direction of the image carrier 1. Developer carrier 41). The developing sleeve 41 carries a developer and rotates to supply the developing sleeve 41 to a portion facing the image carrier 1. The developing device 4 is preferably a two-component developing device that develops using a two-component developer having toner and carrier to form a toner image, and performs development with toner charged to the same polarity as the charged polarity of the image carrier 1. A reversal developing type developing device is particularly preferred.

  As the primary transfer unit 5, a transfer roller is preferably used. The primary transfer means 5 of this embodiment is composed of a semiconductive rubber roller, and applies a transfer voltage having a polarity opposite to that of the toner to the transfer roller 5R that presses the intermediate transfer body 70 against the image carrier 1 and the transfer roller 5R. Consists of a transfer power source 5E, and the intermediate transfer member 70 is pressed against the image carrier 1 to transfer the toner image from the image carrier 1 to the intermediate transfer member 70. It is preferable that the transfer roller 5 </ b> R is urged by a spring to press the intermediate transfer member 70 against the image carrier 1.

  The cleaning device 6 is preferably a cleaning device that scrapes and cleans the toner on the image carrier 1 with a cleaning blade made of rubber such as urethane rubber.

  By rotation of the image carrier 1 indicated by an arrow, a toner image is formed on the image carrier 1 by charging, exposure, and development, and the formed toner image is transferred to the intermediate transfer member 70 by the primary transfer unit 5. . The charging device 2, the exposure device 3, and the developing device 4 constitute an image forming unit that forms a toner image on the image carrier 1.

  The image carrier 1 after the transfer is cleaned by the cleaning device 6, but the image carrier 1 is coated with a lubricant over the entire width in the width direction of the image carrier by the lubricant application means 30 upstream of the cleaning device 6. The The lubricant applying unit 30 in this embodiment includes a brush roller 33, a lubricant supply body 31, a spring 32, and a support plate 34.

  The brush roller 33 preferably has brush bristles of conductive fibers, contacts the lubricant supply body 31 with a predetermined pressure and a predetermined bite amount under the biasing force of the spring 32, and has a predetermined pressure and a predetermined It is installed so as to come into contact with the image carrier 1 with the amount of biting. The brush roller 33 rotates so that the peripheral surface thereof moves in the same direction as the peripheral surface of the image carrier 1 as the image carrier 1 rotates, and scrapes the lubricant from the lubricant supplier 31 little by little. It is continuously applied to the carrier 1.

  The lubricant is applied to the surface of the image carrier and is generally composed of a fatty acid metal salt. Specific examples of lubricants include metal stearate such as zinc stearate, aluminum stearate, copper stearate, magnesium stearate, zinc oleate, manganese oleate, iron oleate, copper oleate, magnesium oleate, etc. Metal oleate, metal palmitate such as zinc palmitate, copper palmitate, magnesium palmitate, metal linoleate such as zinc linoleate and zinc linoleate, metal ricinoleate such as zinc ricinoleate and lithium ricinoleate Salts, and the like, metal stearates are preferred, and zinc stearate is particularly preferred.

  FIG. 2 shows the configuration of the lubricant removing members 75Y, 75M, 75C, and 75K. Since the lubricant removing members 75Y, 75M, 75C, and 75K have the same configuration, the reference numeral YMCK is omitted in FIG.

  As shown in FIG. 2, the lubricant removing member 75 is provided at a position downstream of the image forming unit 10 in the moving direction of the intermediate transfer body 70 and extends over the entire width of the intermediate transfer body 70. The leading edge is provided so as to come into contact with the intermediate transfer member 70, and the lubricant on the intermediate transfer member 70 is scraped and removed by the movement of the intermediate transfer member 70.

  The lubricant removing member 75 is a sheet-like member made of an elastic material such as PET (polyethylene terephthalate), for example, and its base end portion is supported by a flat support plate 76 and the leading edge is an intermediate transfer member 70. It is provided so that it may contact | abut on the surface.

  The lubricant removing member 75 and the support plate 76 are moved in the direction indicated by the arrow X by a moving means 53 (see FIG. 5) such as a cam and a solenoid, and can contact and separate from the intermediate transfer member 70. While the image forming area on the body 70 passes, it is separated from the intermediate transfer body 70 and is not in contact.

  Further, a pressing device (not shown) that presses the lubricant removing member 75 in the direction from the proximal end side to the distal end side of the lubricant removing member 75 via the support plate 76 is provided.

  Here, with reference to FIG. 2 to FIG. 4, details of control in the image forming operation by the control unit 50 will be described in detail.

  In FIG. 3, in the case of copying (image formation) on two transfer materials P, the image carrier 1 is rotated, the brush roller 33 of the lubricant applying means 30 is rotated, the developing sleeve 41 is rotated, An example of the timing chart of the transfer voltage output of the next transfer means 5, the contact of the lubricant application member 75, the separation drive, etc. is shown. In FIG. 3, processes such as charging, exposure, and developing bias application are omitted, and only important parts are shown together.

  The operation timing of each color component of yellow (Y), magenta (M), cyan (C), and black (K) is different for each color, but is set to a timing at which images overlap on the intermediate transfer body 70. Here, yellow (Y) will be described as a representative, but the outline of the operation is the same for other colors.

  First, at time t0 (not shown), a start key (none of which is not shown) on the operation panel of the image forming apparatus main body is pressed, and then the control means 50 drives the drive motor of the image carrier 1 at time t1. Is started, the image carrier is rotated, the drive motor of the intermediate transfer member 70 is started, and the intermediate transfer member is rotated. The lubricant applying means 30 scrapes the lubricant with a brush roller 33 that always rotates and supplies the lubricant to the image carrier 1 when the image carrier rotates, and is continuously applied to the entire peripheral surface including the non-image forming area and the image forming area. Apply a lubricant.

  In this specification, an area where a toner image is to be formed by the toner image forming unit on the surface of the image carrier 1 is referred to as an “image forming area”. Specifically, for example, an area based on normal image data or a region where a toner patch image for the purpose of controlling image density and gradation is to be formed.

  Further, the surface area of the image carrier 1 during the idle rotation (pre-rotation) of the image carrier 1 before one or two or more consecutive image forming operations, and the idle rotation of the image carrier 1 subsequently performed. The surface area of the image carrier 1 during (post-rotation), or the image formation area where a toner image is to be formed in one image forming operation on the surface of the image carrier 1, and the next image formation An area other than the image forming area, which is an area between the image forming area where the toner image is to be formed in the operation, is referred to as a “non-image forming area”.

  Here, “idle rotation” means that the image carrier 1 is rotated without an image forming operation, and the idling of the image carrier that is performed before one or a plurality of continuous image forming processes ( Pre-rotation), idle rotation (post-rotation) of the image carrier performed between the end of the image forming process and the stop of the machine.

  In the present embodiment, as shown in FIG. 3, when the rotation of the image carrier 1 is started at time t1, the developing sleeve 41 that is rotationally driven by a drive system different from the image carrier 1 is still rotationally driven. Not done. The developing sleeve 41 is the image forming area of the first recording material P after the non-image forming area (pre-rotation) until the image carrier 1 rotates stably passes the position of the developing sleeve 41. At the time t2 when the leading edge of the toner reaches the position of the developing sleeve 41, it is controlled so as to start rotational driving. As a result, the developer is supplied to the image forming area of the image carrier 1 to develop the latent image.

  As described above, since the driving of the developing sleeve 41 is started when the leading edge of the image forming area reaches the position of the developing sleeve 41, the developing sleeve 41 is rotationally driven while the image forming area passes the position of the developing sleeve 41. Therefore, the lubricant applied to the image forming area is easily taken into the developing device, the amount of the applied lubricant is decreased, and the amount transferred to the intermediate transfer member is small. On the other hand, while the previous non-image forming area passes through the position of the developing sleeve 41, the driving of the developing sleeve 41 is stopped, and the lubricant applied to the non-image forming area is not taken into the developing device. Since it passes through the position of the developing sleeve 41 as it is, the applied lubricant remains as it is, and the amount of transfer to the intermediate transfer member thereafter increases.

  As described above, the lubricant applied to the non-image forming area has a large amount to be transferred to the intermediate transfer member, and as a result, the influence on the cleaning failure is increased. It is important to remove it.

  When a predetermined time elapses after the developing sleeve 41 is rotationally driven and the time t3 is reached, the leading end of the image forming area reaches the position of the primary transfer unit 5 and a transfer voltage is applied to the primary transfer unit 5 and the intermediate transfer member The primary transfer to 70 is started. Since the primary transfer unit 5 is always in pressure contact with the image carrier 1 via the intermediate transfer member 70, the lubricant applied to the non-image forming area is intermediate when passing through the position of the primary transfer unit 5. The transfer is made to the transfer body 70.

  On the other hand, at the time t4 when the leading edge of the image forming area in the intermediate transfer body 70 reaches the position of the lubricant removing member 75 after the start of the primary transfer, the lubricant removing member 75 is brought into contact with the intermediate transfer body 70 so far. Separate from the state. Thereby, when the image forming area passes through the position of the lubricant removing member 75, the toner image formed in the image forming area is not scraped off. Further, the lubricant that has moved to the non-image forming area before the image forming area of the intermediate transfer body 70 can be scraped off by the lubricant removing member 75.

  Next, at time t5 when the rear end of the image forming area reaches the position of the developing sleeve 41 by the rotation of the image carrier 1, the rotational driving of the developing sleeve 41 is stopped. Further, at time t6 when the rear end of the image forming area reaches the position of the primary transfer unit 5, the transfer voltage application to the primary transfer unit 5 is stopped. Thereafter, at time t7 when the rear end of the image forming area in the intermediate transfer body 70 reaches the position of the lubricant removing member 75, the lubricant removing member 75 is brought into contact with the intermediate transfer body 70 from the separated state. As a result, the lubricant transferred to the non-image forming area behind the image forming area of the intermediate transfer body 70 can be scraped off by the lubricant removing member 75.

  This completes the operation from the start of the first sheet recording operation to the primary transfer and lubricant removal. Next, the recording operation for the second sheet starts when the developing sleeve 41 starts to rotate at time t8, but basically the same effect can be obtained by following the control for the first sheet. A detailed description that repeats the above description will be omitted, and only different points will be described briefly.

  Continuing from the first image forming operation, the image recording body 1 is driven to rotate, and the second sheet recording operation is started while the lubricant is continuously applied.

  While the rotation of the developing sleeve 41 is stopped between times t5 and t8, the non-image forming area (inter-paper area) of the image carrier 1 passes through the position of the developing sleeve 41, and the applied lubricant is The intermediate transfer member 70 is removed, but is removed by the lubricant removing member 75.

  At time t11, the rotation of the developing sleeve 41 for developing the second sheet is stopped, and after a predetermined time after the primary transfer of the second sheet is completed at time t12, the image carrier 1 is driven to rotate at time t14. Stop. The rotation of the brush roller 33 is also stopped, and the application of the lubricant is ended. While the rotation of the developing sleeve 41 is stopped between times t11 and t14, the non-image forming area (post-rotation) of the image carrier 1 passes through the position of the developing sleeve 41, and the applied lubricant is intermediate. Although transferred to the transfer body 70, it is removed by the lubricant removing member 75.

  FIG. 4 shows the non-image formation formed before and after the image forming area formed on the intermediate transfer body 70 and the image forming area in the moving direction of the intermediate transfer body when the configuration of the present embodiment described above is adopted. The region is schematically shown, and the timing of contact and separation (contact release) of the lubricant removing member 75 when passing the position of the lubricant removing member 75 is shown.

  In FIG. 4, GA1 is the first image forming area, GA2 is the second image forming area, and the shaded area is the non-image forming area where only the lubricant is attached.

  FIG. 5 is a block diagram illustrating a control configuration of contact / separation control of the lubricant removing member according to the present embodiment. Only the control configuration related to the contact / separation control of the lubricant removing member is shown, and the other control configurations are omitted. The control unit 50 that performs contact / separation control of the lubricant removing member according to the program is mainly composed of the following parts.

  The image carrier drive motors 54Y, 54M, 54C, and 54K are motors that drive the image carriers 1Y, 1M, 1C, and 1K, respectively, and are driven and controlled by the control unit 50.

  The intermediate transfer body drive motor 55 is a motor that drives the intermediate transfer body 70, and is driven and controlled by the control unit 50.

  The developing sleeve drive motors 51Y, 51M, 51C, and 51K are motors that drive the developing sleeves 41Y, 41M, 41C, and 41K, respectively, and the image carrier 1 is rotated while the image carrier 1 is rotated by the control unit 50. When the image forming area passes through the position of the developing sleeve, the image forming area rotates, and when the non-image forming area passes, the rotation is stopped.

  Lubricant removal member moving means 53Y, 53M, 53C, and 53K switch between contact and separation of the lubricant removal members 75Y, 75M, 75C, and 75K with respect to the intermediate transfer body 70, respectively.

  The control means 50 controls the operation of the image bearing member drive motor and the intermediate transfer member drive motor to rotate the image carrier and the intermediate transfer member at the start of the image forming operation, and controls the operation of the developing sleeve drive motor. When there is a non-image forming area around the circumferential direction of the image carrier at the position of the developing sleeve, the rotation of the developing sleeve is stopped, and the developing sleeve is driven to rotate when there is an image forming area. The control unit 50 controls the operation of the lubricant removing member moving unit based on the rotation state of the developing sleeve of the developing device of the image forming unit located on the upstream side of the lubricant removing member in the moving direction of the intermediate transfer member. Then, after a predetermined time after the developing sleeve starts to rotate, the lubricant removing member is separated from the normal contact state with respect to the intermediate transfer member, and then after a predetermined time after the developing sleeve stops rotating. Switch back to the contact state.

  For example, after removing the lubricant removing member 75Y from the normal contact state with respect to the intermediate transfer body 70 after a first predetermined time after the developing sleeve 41Y starts rotating, The developing sleeve 41Y is switched to return to the contact state after a second predetermined time after the rotation stops.

  During the first predetermined time, after the tip of the image forming area of the image carrier 1Y reaches the position of the developing sleeve 41Y by the rotation of the image carrier 1Y, the tip of the image forming area of the intermediate transfer member 70 is removed with the lubricant. This is the time until the position of the member 75Y is reached, and is the time from time t2 to t4 in the first recording in FIG.

  During the second predetermined time, after the rear end of the image forming area of the image carrier 1Y reaches the position of the developing sleeve 41Y by the rotation of the image carrier 1Y, the rear end of the image forming area of the intermediate transfer member 70 is lubricated. This is the time until the position of the agent removing member 75Y is reached, and is the time between time t5 and time t7 in the first recording in FIG.

  The lubricant removing member 75M separates the lubricant removing member 75M from the normal contact state with respect to the intermediate transfer body 70 after a first predetermined time after the developing sleeve 41M starts rotating, The developing sleeve 41M is switched so as to return to the contact state after a second predetermined time after the rotation stops. Hereinafter, C and K are similarly controlled.

  The storage unit 52 stores, in addition to the control program, the first predetermined time and the second predetermined time of each color, which are obtained in advance by experiment, for each color individually or in the case where they are the same numerical value. The control means 50 reads the value stored in the storage unit 52 and controls the contact / separation of the lubricant removing member.

  The control unit 50 uses the lubricant removing member as the intermediate transfer body based on the rotation state of the developing sleeve of the developing device of the image forming unit located upstream of the lubricant removing member in the moving direction of the intermediate transfer body 70. For example, the contact and separation of the lubricant removing members 75Y, 75M, 75C, and 75K can be controlled based on the rotation state of the developing sleeve 41Y.

  As described above, during the image forming operation, with the image carrier and the intermediate transfer member rotating, a series of image formation is performed by controlling the contact and separation of the lubricant removing member based on the rotation state of the developing sleeve. Since the lubricant can be removed during operation, it is not necessary to provide a special cleaning mode for removing the lubricant on the intermediate transfer member, and the control can be simplified.

  Further, the drive timing and stop timing of each member are not limited to the above-described configuration. The lubricant removing member may be brought into contact with the intermediate transfer member region where the lubricant is applied and the toner image is not formed. For example, while the rotation of the intermediate transfer member is stopped, the intermediate transfer member is kept in a separated state, and when the image forming operation starts, the image carrier or the intermediate transfer member contacts with the rotation of the intermediate transfer member at the same time or after the rotation of the intermediate transfer member starts. The tip of the lubricant application area in the non-image forming area is brought into contact with the timing until it reaches the position of the lubricant removing member. After the image forming operation is completed and the image carrier is stopped, the intermediate transfer body is moved by the intermediate transfer body. The rear end of the lubricant application region on the body may be separated after reaching the lubricant removing member position.

  Further, a slight margin is provided for the contact and separation timing of the lubricant removing member 75, and lubrication is performed slightly before the time (for example, t4 and t10 in FIG. 3) when the leading edge of the image forming area reaches the position of the lubricant removing member 75. The lubricant removal member 75 is separated from the contact state, and the lubricant removal member 75 is removed from the separation state slightly after the time (for example, t7 and t13 in FIG. 3) when the rear end of the image forming region reaches the position of the lubricant removal member 75. You may make it contact | abut.

  The timing of driving the developing sleeve is not limited to the configuration of the present embodiment, and the developing sleeve may be driven and rotated when the non-image forming area passes. However, as described in the present embodiment, when the driving of the developing sleeve is stopped when the non-image forming area passes, the lubricant applied to the non-image forming area moves to the intermediate transfer member. Since the amount increases and as a result, the influence on the cleaning failure becomes large, the effect of the present invention that can reliably remove the lubricant in the non-image forming region is remarkably exhibited. In addition, shortening the developing sleeve drive time as much as possible has the advantage that the developer is less likely to deteriorate.

  As described above, in the configuration of this embodiment, in the four-color full-color electrophotographic image forming apparatus as described with reference to FIG. The lubricant is applied for each color in the non-image forming areas before and after the area. These lubricants are applied together by the pressing force of the primary transfer means 5Y, 5M, 5C, and 5K when the toner images of the respective colors are transferred to the intermediate transfer body 70 by the primary transfer means 5Y, 5M, 5C, and 5K. The images are sequentially transferred onto the intermediate transfer body 70. As a result, the toner images of the respective colors are superimposed on the intermediate transfer body 70. Similarly, the lubricant for the image carrier of each color is also superimposed on the intermediate transfer member 70. As a result, in the case of a four-color full-color image forming apparatus as in the present embodiment, these lubricants overlap by four colors and pass through the secondary transfer position with the rotation of the intermediate transfer body 70, and then the cleaning device 60. It is conveyed to. As a result, a cleaning failure occurs in the cleaning device 60.

  As described in the problem to be solved by the invention, it is difficult to remove excess lubricant on which lubricants from a plurality of image carriers are superimposed by one contact with the lubricant removing member. In addition, if it is arranged downstream of the cleaning device as in the prior art, there is no effect on cleaning failure, and cleaning failure occurs.

  In the present exemplary embodiment, a lubricant removing member is disposed between two adjacent image forming units, and the lubricant is removed each time the lubricant moves from the upstream image forming unit to the intermediate transfer member. Thus, at least a part of the lubricant adhering to the non-image forming regions before and after the image forming region is removed before overlapping on the intermediate transfer body 70. As a result, it is possible to effectively remove the excessively applied lubricant from the plurality of image bearing members to the intermediate transfer member, and to suppress fluctuations in the contact angle due to variations in the amount of lubricant on the intermediate transfer member. In addition, poor cleaning of the intermediate transfer member can be prevented.

  In particular, in the pre-rotation and post-rotation of the image carrier, the lubricant is applied to the entire surface of the image carrier, that is, the entire width × the entire circumference every time the image carrier rotates once. More lubricant is applied than non-imaged areas between. Therefore, the amount of lubricant applied is increased by intermittently copying the same number of sheets one by one rather than by performing continuous copying of a plurality of sheets. In a conventional apparatus such as Patent Document 1, for example, When a plurality of copies are made intermittently one by one, the contact angle changes greatly and a cleaning failure occurs. However, in this embodiment, the cleaning failure can be prevented even in such a case.

  In the present embodiment, the lubricant transferred to the intermediate transfer member 70 is removed by the lubricant removing member 75 before reaching the secondary transfer unit 5A. Therefore, the amount of lubricant transferred to the secondary transfer unit 5A is reduced. It is possible to suppress the transfer failure during the secondary transfer.

  In the present embodiment, the effect can be obtained only by disposing the lubricant removing members 75Y, 75M, and 75C between two adjacent image forming units among the Y, M, C, and K image forming units. However, it is most effective and preferable to arrange 75K downstream of K.

  In particular, the edge of the cleaning blade that is in contact with the surface of the intermediate transfer member is sharp immediately after the device is shipped from the factory or immediately after the replacement of the intermediate transfer member in the maintenance work. , The frictional resistance of the contact portion is increased, and cleaning failure is likely to occur.

  Therefore, the control unit 50 is preferably configured to change the contact condition between the lubricant removing member and the intermediate transfer member based on the operation history based on the initial state of the cleaning blade 61 of the cleaning device 60. For example, a counter that counts the operation history is provided, and the control unit 50 changes the contact condition based on the operation history counted by the counter. As the operation history, for example, the number of passing sheets and the rubbing distance of the cleaning blade 61 may be counted. For example, when the number of sheets passed from the initial state and the rubbing distance are equal to or less than a predetermined threshold, the first contact condition is set so that the removal capability of the lubricant removing member is increased, and the number of sheets to be passed and the rubbing distance are When the predetermined threshold value is exceeded, the second contact condition is set so that the removal ability of the lubricant removing member is lower than the first contact condition.

  Ease of cleaning failure is also affected by temperature and humidity. When the temperature of the atmosphere decreases or when the humidity decreases, the blade becomes hard, the frictional resistance of the contact portion increases, and cleaning failure is likely to occur. .

  Therefore, the control unit 50 preferably has a configuration in which the contact condition between the lubricant removing member and the intermediate transfer member is changed based on at least one of the temperature and humidity of the atmosphere in which the image forming apparatus is installed. For example, a detection unit that detects the temperature and humidity of the atmosphere in the image forming apparatus is provided, and the control unit 50 changes the contact condition based on the detection result. For example, when the temperature and humidity are equal to or lower than a predetermined threshold, the first contact condition is set so that the removal capability of the lubricant removing member is high, and when the predetermined threshold is exceeded, the lubricant removing member The second contact condition is set so that the removal capability is lower than the first contact condition.

  The contact condition preferably includes at least one of a contact time, a contact pressure, and a contact angle when the lubricant removing member is in a sheet form, and a contact time when a rotating body such as a urethane foam roller is used. Preferably, at least one of the contact pressures is included. The removal capability increases by increasing the contact time, increasing the contact pressure, or decreasing the contact angle θ (see FIG. 2).

  As described above, by appropriately changing the contact condition, sufficient lubricant removal performance can be exhibited without causing unnecessary damage to the surface of the intermediate transfer member.

  Since the threshold value and the contact condition vary depending on the structure of the image forming apparatus and the like, it is preferable to use a value obtained in advance through experiments or the like and stored in the storage unit 52.

  A specific mechanical configuration for changing the contact angle and the contact pressure is not particularly limited, and a conventionally known one can be used. For example, the support plate 76 in FIG. The contact angle θ of the lubricant removing member 75 with respect to the intermediate transfer body 70 can be changed in multiple stages by rotating through the support plate 76. Further, as a pressing device, an urging member such as a spring is provided between the movable base member and the support plate 76, and the support plate 76 is urged by the urging member to push the lubricant removing member 75 against the intermediate transfer body 70. The movable base member is moved by the moving means in the direction approaching the support plate 76 to increase the amount of compression of the urging member to increase the pressing force, and is moved away from the support plate 76 to be urged. The pressing force can be lowered by reducing the compression amount of the member.

  The contact time, the contact pressure, and the contact angle may be configured so that a threshold value of 2 or more is set and can be changed in multiple stages of 3 or more.

  By the way, the present embodiment has been described with respect to an image forming apparatus that forms four color images. However, the number of color images is not limited to this, and the present invention is applicable to an image forming apparatus that forms two or more color images. Is possible. In the case of two colors, a lubricant removing member may be disposed between two image forming portions. In the case of three or more colors, a lubricant removing member is disposed between two adjacent image forming portions. Just do it.

Using the image forming apparatus shown in FIG. 1, in the color mode, the lubricant removal member installation conditions were changed and printing was performed to evaluate the contact angle and cleaning failure of the intermediate transfer member.
-Items common to comparative examples and examples-
Image bearing member: OPC photosensitive member Intermediate transfer member: Endless polyimide belt (volume resistance: 10 ⁹ Ω · cm, surface resistance 10 ¹¹ / Ω □)
Primary transfer means: transfer roller: resistance 10 ⁷ Ω, transfer current 30 μA
Toner: Polymerized toner having a volume average particle size of 4.5 μm Lubricant: Zinc stearate Lubricant removing member: PET sheet Intermediate transfer member cleaning device: Cleaning blade method
Original / transfer material size: A4
Color mode: Full color (4 colors) mode (see time chart in Fig. 3)
The number of prints per time (the number of transfer material output per time): 100 copies were made intermittently at one time.
-Lubricant removal member installation conditions-
Using the image forming apparatus shown in FIG. 1, the installation conditions of the lubricant removing member were set as follows.
Example 1: The lubricant removing member 75K was removed and only 75Y, 75M, and 75C were installed.
Example 2: Lubricant removing members 75Y, 75M, 75C, and 75K were installed.
Comparative Example 1: The lubricant removing members 75Y, 75M, 75C, and 75K were all removed, and no lubricant removing member was installed.
Comparative Example 2: The lubricant removing members 75Y, 75M, 75C, and 75K were all removed, and the lubricant removing member 75 was installed between the cleaning device 60 and the image forming unit 10Y.
Comparative Example 3: The lubricant removing members 75M, 75C, and 75K were removed, and only 75Y was installed.
Comparative Example 4: The lubricant removing members 75C and 75K were removed, and only 75Y and 75M were installed.

  Under the above six conditions, the visual evaluation of poor cleaning due to slipping of the cleaning device 60 during 100 copies and the contact angle with water of the intermediate transfer body 70 after 100 copies were evaluated. The results are shown in Table 1.

  In each of the six conditions, the contact angle of the intermediate transfer body 70 with water in the state where the lubricant was not applied before the copying of 100 sheets was about 75 degrees.

  The results are shown in Table 1.

  As shown in Table 1, in Examples 1 and 2, the lubricant removing members 75Y, 75M, and 75C are disposed between two adjacent image forming units among the Y, M, C, and K image forming units. By doing so, it is possible to suppress the change in the contact angle and prevent defective cleaning. In particular, in Example 2, it is confirmed that the change in the contact angle can be suppressed very well by arranging 75K further downstream of K. did it. Further, in Comparative Examples 1 to 4, it was confirmed that the contact angle greatly changed and the cleaning failure could not be prevented.

1, 1Y, 1M, 1C, 1K Image carrier 4, 4Y, 4M, 4C, 4K Developing device 41, 41Y, 41M, 41C, 41K Developing sleeve (developer carrier)
70 Intermediate transfer body 75, 75Y, 75M, 75C, 75K Lubricant removing member

Claims (9)

An intermediate transfer member;
An image carrier, a lubricant applying means for applying a lubricant to at least a non-image forming area of the image carrier, a developing device for forming a toner image on the image carrier, and a toner image on the image carrier. A plurality of image forming units each provided with a primary transfer means for transferring the image to the intermediate transfer member;
A cleaning member for cleaning residual toner on the intermediate transfer member after the secondary transfer;
A lubricant removing member that is disposed in a position between the two image forming units adjacent to each other in the moving direction of the intermediate transfer body so as to be able to contact with and separate from the intermediate transfer body, and removes the lubricant on the intermediate transfer body;
Control means for contacting and separating the lubricant removing member and the intermediate transfer member;
An image forming apparatus comprising:   When the non-image forming region on the intermediate transfer member passes through the position of the lubricant removing member, the control unit brings the lubricant removing member and the intermediate transfer member into contact with each other on the intermediate transfer member. The image forming apparatus according to claim 1, wherein the lubricant is removed.   2. The control unit separates the lubricant removing member and the intermediate transfer member when an image forming region on the intermediate transfer member passes through the position of the lubricant removing member. Or the image forming apparatus according to 2;   The control means is configured to control the lubricant removing member and the intermediate transfer member based on the rotation state of the developer carrying member of the developing device of the image forming unit located upstream of the lubricant removing member in the moving direction of the intermediate transfer member. The image forming apparatus according to claim 1, wherein the body is brought into contact with or separated from the body.   The apparatus further comprises a lubricant removing member disposed upstream of the cleaning member and downstream of the most downstream image forming unit among the plurality of image forming units with respect to the moving direction of the intermediate transfer member. The image forming apparatus according to claim 1.   6. The control unit according to claim 1, wherein the control unit changes a contact condition between the lubricant removing member and the intermediate transfer member based on an operation history based on an initial state of the cleaning member. The image forming apparatus according to claim 1.   The control unit changes a contact condition between the lubricant removing member and the intermediate transfer body based on at least one of temperature and humidity of an atmosphere in which the image forming apparatus is installed. The image forming apparatus according to any one of 1 to 6.   The image forming apparatus according to claim 6, wherein the contact condition includes at least one of a contact time and a contact pressure. The lubricant removing member is composed of a sheet-like member,
The image forming apparatus according to claim 6, wherein the contact condition includes at least one of a contact time, a contact pressure, and a contact angle.

Images