JP4564137B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image by an electrophotographic method such as a copying machine, a printer, and a facsimile machine.
[0002]
[Prior art]
The image forming apparatus illuminates a document placed on a document table with an exposure light source, projects the reflected light on a CCD sensor to form an image, and converts the light image into an image signal that is an electrical signal. Output to the laser device of the image forming device. The laser device projects a laser beam modulated by an image signal onto a charged photosensitive member to form an electrostatic latent image of the image, and develops the electrostatic latent image of the image with toner to visualize it. Next, the visualized toner image is transferred onto a recording medium, and the toner image is melted and pressed by a fixing and heating rotator such as a heating roll to be fixed on the recording medium. Has been.
[0003]
In a color image forming apparatus, reflected light from a color original is separated into three primary colors of red (R), green (G), and blue (B) by a CCD sensor, and modulated by image signals of these separated colors. The laser beam is projected onto a charged photoreceptor to form electrostatic latent images of images corresponding to the respective colors, and these electrostatic latent images are respectively converted into yellow (Y), magenta (M), and cyan (C). , Developed with black (K) toner, and the resulting toner images of each color are sequentially superimposed and transferred onto an intermediate transfer member such as a transfer drum or belt, and the superimposed color toner image is transferred onto a recording medium. An image is recorded through a process of transferring and fixing the image on a recording medium by being melted and pressed by a fixing heating rotator such as a heating roll.
[0004]
When transferring the toner image formed on the photosensitive member onto the intermediate transfer member or the recording medium, it is impossible to transfer the toner image to 100%, and depending on the environmental conditions, only about 80 to 90% can be transferred. There may not be. Such a transfer defect appears on the transferred image as a reduction in image quality such as a finer line image becoming thinner or an image density decreasing.
[0005]
Recently, contact transfer means has been adopted as transfer means. However, in the contact transfer means, the toner images on the photoreceptor are agglomerated by pressing and remain on the photoreceptor without being transferred. A phenomenon called a hollowing out phenomenon occurs.
[0006]
In order to solve these disadvantages, conventionally, a lubricant is applied to the photoreceptor such as by applying a metal stearate salt, or a CT layer formed on the photoreceptor (a carrier transport layer for transporting optical carriers). In order to make the toner image easy to separate from the photosensitive member, for example, by adding fluorine fine particles to the toner, the releasability has been improved. Here, the method of adding fluorine fine particles to the CT layer of the photoreceptor has a problem in high-definition image formation because light projected onto the photoreceptor is scattered by the fluorine fine particles. The method of supplying is adopted.
[0007]
[Problems to be solved by the invention]
The tandem image forming apparatus has four image forming units of yellow (Y), magenta (M), cyan (C), and black (K) arranged in series, and approaches the photoreceptor inside each image forming unit. Then, a transfer belt, which is an intermediate transfer body, is arranged, and toner images formed on the photoreceptors of the four image forming units are sequentially superimposed and transferred on the transfer belt as the transfer belt moves. It is equipped with the structure.
[0008]
In such a tandem type image forming apparatus, when it is intended to supply lubricant to each photoconductor of a plurality of image forming units via a transfer belt, the lubricant to the photoconductor becomes closer to the downstream side in the moving direction of the transfer belt. The supply amount of the lubricant decreases, and a gradient occurs in the lubricant supply amount from the upstream side to the downstream side. As a result, the toner image releasability of the downstream image forming unit, that is, the releasability of the toner image being separated from each photoconductor and transferred to the transfer belt is deteriorated, and the quality of the transferred image is deteriorated. There is an inconvenience. The present invention aims to solve the above-mentioned problems.
[0009]
[Means for Solving the Problems]
According to the present invention, in a configuration in which a lubricant is supplied to each photoconductor of a plurality of image forming units via a transfer belt, the amount of lubricant supplied to each photoconductor is adjusted, and the toner image releasing performance on the photoconductor Is to be uniform among the photosensitive members to solve the above problem.
[0010]
  The invention of claim 1 is arranged in series along the moving direction of the transfer body., EachA plurality of image forming units each including an image carrier;Of each image forming unitThe toner image formed on the image carrierSaidA first transfer means for transferring to the transfer body;ReprintAn image forming apparatus comprising: a second transfer unit that transfers a toner image transferred to a copy body to a recording medium.ReprintFirst lubricant supply means for supplying a lubricant to the surface of the copy body, and a plurality of lubricants supplied to the surface of the transfer body by the first lubricant supply means.Of the image forming unitA second lubricant supply means for re-supplying the image carrier, and a control means for controlling the second lubricant supply means, the control means comprising:When the portion of the transfer body to which the lubricant is supplied by the first lubricant supply means reaches a position facing each of the image carriers of the plurality of image forming units, it is supplied to the surface of the transfer body. While controlling the lubricant to be re-supplied substantially uniformly to each image carrier,When the image transferability of a specific image forming unit has deteriorated,in frontLubricant only for image carrier of specific image forming unitTheResupplyDoThe image forming apparatus is controlled as described above.
[0011]
  AndThe control means can adjust the supply amount of the lubricant resupplied by controlling the pressing force that presses the transfer member against the image carrier.
[0012]
  The control unit may adjust a supply amount of the lubricant that is resupplied by controlling an electric field applied between the transfer member and the image carrier..
[0013]
  The invention according to claim 4 is arranged in series along the moving direction of the transfer body, each of which is formed on a plurality of image forming units each including an image carrier and the image carrier of each of the image forming units. An image forming apparatus comprising: a first transfer unit that transfers a toner image to the transfer body; and a second transfer unit that transfers a toner image transferred to the transfer body to a recording medium. A first lubricant supply means for supplying a lubricant to the second surface, and a second lubricant supplied to the surface of the transfer body by the first lubricant supply means to the image carriers of the plurality of image forming units. A part of the lubricant resupplied to each image carrier by the second lubricant supplier and the second lubricant supplier is finally resupplied to each image carrier. Lubricant scraping to adjust the amount of lubricant to be almost uniform Means Ri, is an image forming apparatus comprising the.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. First, an outline of the configuration of the image forming apparatus will be described. FIG. 1 is a cross-sectional view illustrating the configuration of a tandem type image forming apparatus 100 according to an embodiment of the present invention.
[0018]
In FIG. 1, an image forming apparatus 100 includes four image forming units 11Y, 11M, 11C, and 11K arranged in series at predetermined intervals, and the image forming units 11Y, 11M, 11C, and 11K are intermediate transfer members. It is arranged close to a certain transfer belt 15.
[0019]
The transfer belt 15 is installed in a state where a predetermined tension is applied between the rollers 13 and 14, and is configured to move at a predetermined constant speed in the direction of arrow a by a driving mechanism (not shown).
[0020]
In each of the image forming units 11Y, 11M, 11C, and 11K, primary transfer rollers 18Y, 18M, 18C, and 18K are arranged on the opposite side of the image forming unit with the transfer belt 15 therebetween, and the primary transfer rollers 18Y, By applying charges to 18M, 18C, and 18K, the toner images formed on the photoreceptors of the image forming units 11Y, 11M, 11C, and 11K can be transferred to the transfer belt 15.
[0021]
A secondary transfer roller 16 is disposed on the roller 13 side with the transfer belt 15 therebetween, and by applying an electric charge to the secondary transfer roller 16, the toner image transferred onto the transfer belt 15 is changed. The image can be transferred onto the recording medium P conveyed between the transfer belt 15 and the secondary transfer roller 16.
[0022]
On the roller 14 side, a lubricant supply device 17 and a cleaning blade 19 are arranged close to the transfer belt 15.
[0023]
The image forming unit 11Y is loaded with yellow (Y) toner and used for forming a yellow image. Similarly, the image forming unit 11M is loaded with magenta (M) toner, the image forming unit 11C is loaded with cyan (C) toner, and the image forming unit 11K is loaded with black (K) toner. It is used to form a toner color image. Here, a case covering the outside of each image forming unit is not shown.
[0024]
The image forming unit will be described. Since each of the image forming units 11Y to 11K has the same configuration although the color of the loaded toner is different, the image forming unit 11Y will be described here.
[0025]
FIG. 2 is a cross-sectional view showing the configuration of the image forming unit 11Y, which includes a photoreceptor 31Y, a charging device 32Y, a developing device 33Y, and a cleaning device 34Y including a cleaning blade 35Y disposed in the periphery thereof. Reference numeral 36Y denotes a laser beam projection device that projects a laser beam modulated by an image signal onto the photoreceptor 31Y to form an image latent image.
[0026]
Next, the operation will be described. Laser light modulated by the image signal of the yellow component from the laser light projection device 36Y is projected onto the photoreceptor 31Y charged by the charger 32Y to form an electrostatic latent image, and the electrostatic latent image is developed by the developing device 33Y. And a yellow toner image is formed on the photoreceptor 31Y. The yellow toner image formed on the photoreceptor 31Y is transferred onto the transfer belt 15 (lower surface in FIGS. 1 and 2) that moves at a predetermined constant speed by the action of the primary transfer roller 18Y (see FIG. 1). .
[0027]
In accordance with the timing at which the yellow toner image transferred onto the transfer belt 15 reaches the position of the image forming unit 11M, the photoreceptor 31M charged with the laser light modulated by the image signal of the magenta component from the laser light projection device 36M. The electrostatic latent image is projected onto the surface, and the electrostatic latent image is developed by the developing device 33M, and a magenta toner image is formed on the photoreceptor 31M. The magenta toner image formed on the photoconductor 31M is superimposed and transferred onto the yellow toner image on the transfer belt 15 by the action of the primary transfer roller 18M.
[0028]
Similarly, the laser light modulated by the cyan component image signal is charged from the laser light projection device 36C in accordance with the timing at which the magenta toner image transferred onto the transfer belt 15 reaches the position of the image forming unit 11C. The electrostatic latent image is formed on the photosensitive member 31C, and the electrostatic latent image is developed by the developing device 33C. A cyan toner image is formed on the photosensitive member 31C. The cyan toner image formed on the photoconductor 31C is superimposed and transferred onto the magenta toner image on the transfer belt 15 by the action of the primary transfer roller 18C.
[0029]
Further, in accordance with the timing at which the cyan toner image transferred onto the transfer belt 15 reaches the position of the image forming unit 11K, the photosensitive member charged with the laser beam modulated by the black component image signal from the laser beam projection device 36K. The electrostatic latent image is projected onto the body 31K, and the electrostatic latent image is developed by the developing device 33K, and a black toner image is formed on the photoreceptor 31K. The black toner image formed on the photoconductor 31K is superimposed and transferred onto the cyan toner image on the transfer belt 15 by the action of the primary transfer roller 18K to form a full-color toner image.
[0030]
The recording medium P is conveyed at the timing when the transfer belt 15 moves and the color toner image transferred and formed on the transfer belt 15 reaches the position of the secondary transfer roller 16, and the color toner image on the transfer belt 15 is The image is transferred to the recording medium P by the action of the secondary transfer roller 16. The color toner image transferred to the recording medium P is fixed by a fixing device (not shown) to complete the recording medium P on which a full color image is recorded.
[0031]
Thereafter, the toner remaining on the transfer belt 15 without being transferred is removed by the cleaning blade 19 and collected in a waste toner container (not shown). In each of the image forming units 11Y to 11K, the toner that is not transferred and remains on the photoreceptors 31Y to 31K is removed by the cleaning blades 35Y to 35K and collected by the cleaning devices 34Y to 34K.
[0032]
Next, a configuration for supplying a lubricant to the photoreceptor and the transfer belt will be described with reference to FIG. The term “lubricant” as used herein refers to a releasability-improving material that facilitates separation of the toner on the photosensitive member or the transfer belt. What is meant by a general lubricant that reduces friction between contacting members? Different.
[0033]
The process of supplying the lubricant to the photosensitive member and the transfer belt is executed during a period when the normal image forming operation is not executed. In this process, first, a lubricant is supplied to the transfer belt 15 using a lubricant supply device 17 described later. When the transfer belt 15 moves and the supplied lubricant reaches the image forming unit 11Y, the primary transfer roller 18Y is pressed toward the photoreceptor 31Y to bring the transfer belt 15 and the photoreceptor 31Y into contact with each other. Thereby, a part of the lubricant of the transfer belt 15 is supplied to the surface of the photoreceptor 31Y. Hereinafter, this is referred to as resupply of the lubricant.
[0034]
Thereafter, by the movement of the transfer belt 15 in the arrow direction, a part of the lubricant on the transfer belt 15 can be sequentially re-supplied to the surfaces of the photoconductor 31M, the photoconductor 31C, and the photoconductor 31K in the same manner as described above. After the lubricant is re-supplied to the last photoconductor 31K, the lubricant remaining on the transfer belt 15 is formed on the lubricant film by the cleaning blade 19, and the old lubricant film is removed and updated.
[0035]
Further, the lubricant re-supplied to each of the photoconductors 31Y to 31K is formed on the lubricant film by the cleaning blades 35Y to 35K of the respective image forming units 11Y to 11K, and the old lubricant film is removed and updated.
[0036]
Adjustment of the amount of lubricant resupplied to the surfaces of the photoreceptors 31Y to 31K is performed by adjusting the pressing force of the primary transfer rollers 18Y to 18K. Lubrication re-supplied to the surfaces of the photoreceptors 31Y to 31K by increasing the pressing force of the primary transfer roller 18 located downstream, that is, downstream of the transfer belt 15 in the moving direction, higher than the pressing force of the upstream roller. The amount of the agent can be adjusted uniformly.
[0037]
The lubricant supply device 17 will be described. FIG. 3 is a side view illustrating the configuration of the lubricant supply device 17, and the lubricant supply device 17 includes a lubricant holding portion 17a and a lubricant supply portion 17b. The lubricant holding part 17a is constituted by a solid lubricant obtained by solidifying a powder lubricant by melt molding or injection molding.
[0038]
As a material for the lubricant, a metal stearate such as Zn stearate, Mg stearate, Al stearate, Ba stearate, Li stearate, Na stearate or stearic acid can be used. However, other fatty acid metal salts, higher alcohols, fluorine-based lubricants and the like generally used as lubricants can be used. The solid lubricant may be produced by pulverization or polymerization in addition to the melt molding or injection molding described above, and the particle diameter is preferably about 0.1 μm or more and 10 μm or less.
[0039]
The lubricant supply unit 17b is a rotating brush that rotates in contact with the solid lubricant. When the rotating brush rotates in contact with the solid lubricant, the solid lubricant is scraped off and supplied to the transfer belt 15 in a powder state. In this embodiment, a rotating brush is used, but a roller or the like can also be used.
[0040]
In the embodiment described above, the transfer belt 15 and the photoconductors 31Y to 31K are brought into contact with each other and the lubricant is resupplied to the surface of the photoconductor. However, the transfer belt 15 and the photoconductors 31Y to 31K are interposed between them. It is also possible to reapply the lubricant by applying a voltage and moving the lubricant electrostatically. It is also possible to increase the photoconductor potential applied to the photoconductors 31Y to 31K immediately before supplying the lubricant to the photoconductor, and to re-supply the lubricant by moving it electrostatically.
[0041]
FIG. 4 is a diagram illustrating the contact angle of pure metal stearate used as a lubricant with respect to pure water. As a measuring device, a fully automatic contact angle meter CA-W150 manufactured by Kyowa Interface Chemical Co., Ltd. was used. The measurement conditions were an average of 3 points with a liquid volume of 200 msec. Stearic acid Mg salt (ST-Mg), stearic acid Al salt (ST-Al), stearic acid Zn salt (ST-Zn), stearic acid Ba salt (ST-Ba), stearic acid Li salt (ST-Li), It can be seen that the contact angle is small in the order of stearic acid (ST) and sodium stearate (ST-Na). Since the releasability of the toner substantially corresponds to the contact angle, the optimum material can be selected based on the measurement result shown in FIG.
[0042]
FIG. 5 is a diagram showing supply conditions and lubricant transfer amount when the lubricant is resupplied from the transfer belt to the photosensitive member. FIG. 5A shows the supply conditions (transfer by pressing of the primary transfer roller). The contact pressure between the belt and the photoconductor is the same for all of the photoconductors 31Y to 31K, and shows the amount of lubricant transferred to the photoconductor of each of the image forming units 11Y to 11K. It is also a value indicating.
[0043]
According to experiments, 40% of the lubricant supplied to the transfer belt is transferred to the photoreceptor.
Assuming that 100 units of lubricant are supplied to the transfer belt 15 based on this result, 40% is transferred to the photoconductor, so 40 units are transferred to the uppermost photoconductor 31Y, and 60 units are transferred to the transfer belt. 15 remains. On the downstream side of the photoconductor 31M, 40% of 60 units, 24 units are transferred, and 36 units remain on the transfer belt 15. Similarly, 40% of the 36 units, 14.4 units are transferred to the photoreceptor 31C, and 21.6 units remain on the transfer belt 15. 40% of the 21.6 units, 8.64 units are transferred to the photoreceptor 31K, and 12.96 units remain on the transfer belt 15. Thus, it can be seen that the amount of transfer of the lubricant decreases as the downstream photoconductor.
[0044]
Accordingly, the lubricant supply conditions set in the image forming units 11Y to 11K are set to different values for the respective image forming units, so that the lubricant re-supply amount is made uniform. That is, the downstream image forming unit (1) increases the contact pressure between the transfer belt 15 supplying the lubricant and the photoconductor, and (2) increases the applied voltage between the transfer belt 15 and the photoconductor. 3) Increase the photoconductor potential, (4) Set a relative speed difference between the transfer belt 15 and the photoconductor, and take other measures to re-supply the lubricant to the image forming units 11Y to 11K. Make uniform.
[0045]
FIG. 5B shows a lubricant supply condition (contact pressure between the transfer belt and the photosensitive member caused by pressing of the primary transfer roller) for each of the image forming units 11Y to 11K, and lubricant to each image forming unit. It is the figure which calculated the supply condition parameter | index A and lubricant transfer amount in the case of making uniform the re-supply amount. By changing the supply condition index A for each of the image forming units 11Y to 11K, the resupply amount of the lubricant to each of the image forming units 11Y to 11K is approximately 24 units.
[0046]
The supply condition index B indicates a supply condition index for each of the image forming units 11Y to 11K when the resupply amount of the lubricant supplied to the image forming unit 11Y is 1.
[0047]
In addition, a lubricant scraping member is provided on each of the photoconductors 31Y to 31K, and a part of the lubricant once resupplied to the photoconductors 31Y to 31K is scraped off, whereby the lubricant resupplied to the photoconductor. The amount of can also be adjusted.
[0048]
FIG. 6 is a cross-sectional view showing an image forming unit in which a lubricant scraping member is provided in the image forming unit described above with reference to FIG. 2, and the image forming unit 11Y is not different from that shown in FIG. Are denoted by the same reference numerals and description thereof is omitted. The image forming units 11M, 11C, and 11K are configured in exactly the same manner.
[0049]
In FIG. 6, the lubricant scraping member 37Y is composed of a rotating brush, and is disposed in contact with the photoreceptor 31Y. The lubricant scraping member 37Y is rotated by a drive mechanism (not shown) for a predetermined time, scrapes a part of the lubricant once resupplied to the photoreceptor 31Y, and adjusts the amount of the resupplied lubricant.
[0050]
The amount of lubricant may be adjusted by adjusting the contact pressure, contact angle, etc. to the photosensitive member, as well as the rotation time of the lubricant scraping member. In the above description, the rotating brush is used as the lubricant scraping member 37Y. However, the lubricant can be scraped off by a roller, a blade, or the like. Further, the cleaning blade incorporated in the image forming units 11Y to 11K can also be used as a lubricant scraping member.
[0051]
FIG. 7 shows the supply conditions (for example, rotating brush rotation time) set in the lubricant scraping member and the amount of lubricant finally transferred to the photoreceptor in order to adjust the amount of lubricant to be resupplied to the photoreceptor. The supply condition index A is calculated so as to finally transfer 5 units of lubricant to the photoconductor. The supply condition index B is a supply condition index when the supply amount of the lubricant to be transferred to the photoreceptor 31K is 1.
[0052]
Among the image forming units 11Y to 11K, when one of the specific image forming units, for example, a black and white image is frequently formed, and the frequency of use of the image forming unit 11K increases, the image transferability compared to other image forming units. Is significantly reduced. For this reason, a difference in image transferability occurs between the image forming units 11Y to 11K, and the image quality is deteriorated.
[0053]
As a countermeasure, by supplying the lubricant only to a specific image forming unit, the releasability with respect to other image forming units, that is, the image transferability can be made substantially equal. For this purpose, (1) a transfer belt 15 for supplying a lubricant is brought into contact with a specific image forming unit, (2) a voltage is applied between the transfer belt 15 and the photoconductor, and (3) photosensitivity. Take measures such as increasing body potential.
[0054]
FIG. 8 is a diagram comparing the transferability before supplying the lubricant and the transferability after supplying the lubricant when the image transferability of the specific image forming unit is lowered. FIG. 8A shows the image formation. FIG. 8B shows an example of the effect of supplying the lubricant when the image transferability of the unit 11K (black toner loading) is lowered. FIG. 8B shows an image forming unit 11Y (yellow toner loading) and an image forming unit 11C ( This is an example showing the effect of supplying lubricant when the image transferability of cyan toner loading is lowered. It is shown that the image transferability is reduced to 0.7, and is restored to 1.0 which is the same as other image forming units by supplying the lubricant.
[0055]
FIG. 9 is a diagram comparing the transferability before adjustment of the lubricant supply amount by the lubricant scraping member and the transferability after adjustment of the lubricant supply amount when the image transferability of a specific image forming unit is lowered. FIG. 9A shows an example of the effect of adjusting the lubricant supply amount when the image transfer property of the image forming unit 11K (black toner loading) is lowered, and FIG. 9B shows the image formation. This is an example showing the effect of adjusting the lubricant supply amount when the image transfer properties of the unit 11Y (yellow toner loading) and the image forming unit 11C (cyan toner loading) are lowered. It is shown that the image transferability is reduced to 0.7, and is restored to 1.0 which is the same as other image forming units by adjusting the supply amount of the lubricant.
[0056]
In the tandem image forming apparatus 100 described above with reference to FIG. 1, a full color image can be formed by using the four image forming units 11Y, 11M, 11C, and 11K. In the case of an image, the image is formed by moving the transfer belt 15 in contact with the image forming unit 11K by the primary transfer roller 18K disposed on the opposite side of the image forming unit, and the other image forming units and the transfer belt. The primary transfer roller is controlled so as not to come into contact with 15.
[0057]
When forming a two-color image, for example, a yellow image and a cyan image, the image is formed by moving the transfer belt 15 in contact with the image forming units 11Y and 11C by the primary transfer rollers 18Y and 18C. The primary transfer roller is controlled so that the image forming unit and the transfer belt 15 do not come into contact with each other.
[0058]
As described above, when the image formation is not performed, the transfer belt 15 and the image forming units 11Y to 11K are not in contact with each other. Therefore, the lubricant is evenly supplied to the image forming units 11Y to 11K using this configuration. be able to.
[0059]
FIGS. 10 to 12 are diagrams for explaining the operation of supplying the lubricant by this method. Since the configuration is the same as that of the image forming apparatus 100 shown in FIG. The operation of supplying the lubricant will be described below.
[0060]
First, at a time when image formation is not performed, the transfer belt 15 and the image forming units 11Y to 11K are separated as shown in FIG. Set. This is achieved by controlling the positions of the primary transfer rollers 18Y to 18K. In this state, the lubricant supply device 17 supplies the lubricant L to the transfer belt 15. FIG. 11 shows a state in which the transfer belt 15 supplied with the lubricant L has moved and the leading end of the lubricant has passed through the photoreceptor 31K of the image forming unit 11K on the most downstream side. At this time, when the transfer belt 15 is moved so as to contact the image forming units 11Y to 11K by the primary transfer rollers 18Y to 18K, the lubricant L on the transfer belt 15 moves to the surfaces of the photoreceptors 31Y to 31K. . FIG. 12 is a diagram showing a state in which the transfer belt 15 supplied with the lubricant L and the photoconductors 31Y to 31K are in contact with each other and the lubricant L is uniformly supplied to the surfaces of the photoconductors 31Y to 31K.
[0061]
FIG. 13 is a view showing a modified example of the recovery of the toner remaining on the transfer belt 15 in the tandem type image forming apparatus 100 described with reference to FIG. 1, and the rollers of the image forming apparatus 100 described with reference to FIG. The cleaning blade 19 disposed on the 14 side is replaced with a toner recovery roller 21. Since the configuration is the same as that of the image forming apparatus 100 shown in FIG. 1 except for the toner collecting roller 21 portion, the same reference numerals are given to the same members, and detailed description thereof will be omitted, and the residual toner collecting operation will be described below. To do.
[0062]
FIG. 13 shows the operation of supplying the lubricant L to the photosensitive member when no image is formed.
[0063]
When a charge having a polarity opposite to that of the residual toner is applied, the toner recovery roller 21 electrostatically attracts the residual toner and recovers it from the transfer belt 15 and temporarily holds it. When the image forming operation is completed, a charge having a polarity opposite to that at the time of adsorption is applied, and the residual toner that has been temporarily collected and held is discharged onto the transfer belt 15. Residual toner discharged onto the transfer belt 15 is transferred to the photoreceptor 31K in a specific image forming unit, in this example, the image forming unit 11K, and finally collected by the cleaning device 34K of the image forming unit 11K.
[0064]
When the image forming unit that finally collects the toner remaining on the transfer belt 15 is on the most downstream side of the plurality of image forming units, in this example, the residual toner is finally obtained by the image forming unit 11K on the most downstream side. In such a case, the residual toner discharged onto the transfer belt 15 is also transferred to the photoreceptors (in this example, photoreceptors 31Y, 31M, and 31C) of the image forming unit on the upstream side. There is an inconvenience that toner adheres and the toner is clogged in the cleaning device (in this example, the cleaning devices 34Y, 34M, and 34C) of the image forming unit.
[0065]
For this reason, in the image forming apparatus shown in FIG. 13, when the image formation is not performed, the photosensitive member is rotated and the transfer belt 15 is moved in the direction of arrow a while the lubricant supply device 17 applies the lubricant L to the transfer belt. 15, the transfer belt 15 is brought into contact with the photoreceptors 31Y, 31M, and 31C of the image forming unit that are not involved in the final recovery of the residual toner, and the lubricant L is supplied to improve the releasability, The photoreceptor 31K of the image forming unit that finally collects the residual toner is set so as not to contact the transfer belt 15, and is configured to collect the residual toner without supplying the lubricant.
[0066]
A second embodiment of the lubricant supply device will be described.
[0067]
FIGS. 14 to 17 show a second embodiment of a lubricant supply device for a transfer belt and a photosensitive member. First, a lubricant is supplied to the photosensitive member of one image forming unit, and then transferred from the photosensitive member. The lubricant is transferred to the belt, and the lubricant is re-supplied to the photoreceptor of another image forming unit.
[0068]
FIG. 14 is a cross-sectional view illustrating the configuration of the image forming unit according to the second embodiment. In the color image forming apparatus, four image forming units having the same configuration are mounted, and only the toner colors to be loaded are different. Therefore, here, one image forming unit will be described.
[0069]
In FIG. 14, 15 is a transfer belt as an intermediate transfer member, 41 is a photosensitive member, and a cleaning device 44 including a charger 42, a developing device 43, and a cleaning blade 45 is disposed around the photosensitive member 41. . A laser light projector 46 projects a laser beam modulated by an image signal onto the photosensitive member 41 to form an image latent image.
[0070]
47A is a lubricant supply device, which is composed of a porous sponge roller containing a powdery lubricant, and is disposed in pressure contact with the photoreceptor 41. With this configuration, the lubricant is supplied to the photoconductor 41, then the lubricant is transferred from the photoconductor 41 to the transfer belt 15, and the lubricant is supplied again to the photoconductor of another image forming unit.
[0071]
FIG. 15 is a cross-sectional view illustrating a second configuration example of the lubricant supply device in the image forming unit according to the second embodiment described with reference to FIG. A lubricant supply device 47B shown in FIG. 15 includes a lubricant holding portion having a mesh-shaped opening on the side surface, and a powdery lubricant is sealed inside. A vibration device (not shown) is provided, and the lubricant is supplied to the photoreceptor 41 by vibrating the lubricant holding portion.
[0072]
FIG. 16 is a cross-sectional view illustrating a third configuration example of the lubricant supply device in the image forming unit according to the second embodiment described with reference to FIG. A lubricant supply device 47 </ b> C shown in FIG. 16 presses the solid lubricant 47 a against the photoconductor 41 by a spring 47 b or the like, and supplies the lubricant to the photoconductor 41.
[0073]
FIG. 17 is a cross-sectional view illustrating a fourth configuration example of the lubricant supply device in the image forming unit according to the second embodiment described with reference to FIG. A lubricant supply device 47D shown in FIG. 17 is a device in which the lubricant supply device 47B described with reference to FIG. 15 is attached to the tip of the lever 47h. It strikes against the photoconductor 41 and supplies lubricant to the photoconductor 41.
[0074]
The lubricant supply device described with reference to FIGS. 14 to 17 is disposed at a position in contact with the photoconductor 41 so as to supply the lubricant to the photoconductor 41 first, but first supplies the lubricant to the transfer belt 15. As described above, the lubricant may be supplied from the transfer belt to the photosensitive member by being disposed at a position in contact with the transfer belt 15.
[0075]
In addition, the lubricant supply device described with reference to FIGS. 14 to 17 can adjust the lubricant supply amount by adjusting the contact time with the photoconductor 41 or the operation time for hitting the photoconductor. .
[0076]
The timing of the lubricant supply operation described above is the operation standby time in the middle of the continuous image forming operation, the start of the image forming operation, after the end of the image forming operation, or after the power is turned on. Although it is performed in the sequence, it may be executed intermittently at the end of a predetermined number of prints, or may be executed when the environmental conditions are set in advance.
[0077]
Further, the arrangement of the lubricant supply device described above is arranged on the downstream side in the transfer belt moving direction from the arrangement position of the transfer belt cleaning device and on the most upstream side of each image forming unit. There is no limitation on the arrangement position as long as the lubricant can be supplied. For example, if the transfer belt cleaning device is detachable from the transfer belt, the lubricant supply device is arranged on the upstream side of the cleaning device, and the cleaning device is detached from the transfer belt at the timing of supplying the lubricant. It may be.
[0078]
【The invention's effect】
  As explained above,According to claim 1According to the invention,FirstLubricant supplymeansFromThe lubricant supplied to the surface of the transfer body is fed by the second lubricant supply means.pluralImage forming unitLubricant for each image carrierReIn that case,By control meansFor each image carrierReOf supplied lubricantAmount is shortUniformlyControlled to beTherefore, an image with good image quality can be created.In addition, when the image transferability of a specific image forming unit deteriorates due to high use frequency among a plurality of image forming units, the lubricant is reapplied only to the image carrier of the specific image forming unit. By controlling the supply, the image transferability of each image carrier of the plurality of image forming units can be adjusted substantially uniformly, so that an image with good image quality can be created.
[0079]
  According to the fourth aspect of the present invention, the lubricant supplied from the first lubricant supply means to the surface of the transfer body is supplied to each image carrier of the plurality of image forming units by the second lubricant supply means. The lubricant can be re-supplied to each image carrier, and at that time, a part of the lubricant re-supplied to each image carrier is scraped off by the lubricant scraping means, so that each image carrier finally Since the amount of lubricant resupplied is adjusted to be substantially uniform,An image with good image quality can be created.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a tandem image forming apparatus.
FIG. 2 is a cross-sectional view illustrating a configuration of an image forming unit.
FIG. 3 is a side view illustrating the configuration of a lubricant supply device.
FIG. 4 is a view for explaining a contact angle of a metal stearate with pure water.
FIG. 5 is a diagram showing lubricant supply conditions and lubricant transfer amount.
FIG. 6 is a cross-sectional view illustrating a configuration of an image forming unit provided with a lubricant scraping member.
FIG. 7 is a diagram showing a relationship between setting conditions set for the lubricant scraping member and the amount of lubricant that finally adheres to the photoreceptor.
FIG. 8 is a diagram comparing the transferability before supplying the lubricant and the transferability after supplying the lubricant when the image transferability of the image forming unit is lowered.
FIG. 9 is a diagram comparing the transferability before adjusting the lubricant adhesion amount by the lubricant scraping member and the transferability after adjusting the lubricant adhesion amount when the image transferability of the image forming unit is lowered.
FIG. 10 is a diagram for explaining a lubricant supply operation (part 1);
FIG. 11 is a diagram for explaining a lubricant supply operation (part 2);
FIG. 12 illustrates a lubricant supply operation (part 3);
FIG. 13 is a view showing a modification of a residual toner collecting device on a transfer belt in a tandem type image forming apparatus.
FIG. 14 is a diagram for explaining a second embodiment of a lubricant supply apparatus (part 1);
FIG. 15 is a (second) diagram illustrating a second embodiment of the lubricant supply apparatus.
FIG. 16 is a diagram (No. 3) for explaining the second embodiment of the lubricant supply apparatus;
FIG. 17 is a diagram illustrating a second embodiment of the lubricant supply apparatus (part 4);
[Explanation of symbols]
11Y, 11M, 11C, 11K Image forming unit
13, 14 Roller
15 Transfer belt (intermediate transfer member)
16 Secondary transfer roller
17 Lubricant supply device
17a Lubricant holding part
17b Lubricant supply unit
18Y, 18M, 18C, 18K Primary transfer roller
19 Cleaning blade
21 Toner recovery roller
31Y, 31M, 31C, 31K photoconductor
32Y, 32M, 32C, 32K charger
33Y, 33M, 33C, 33K Developer
34Y, 34M, 34C, 34K Cleaning device
35Y, 35M, 35C, 35K Cleaning blade
36Y, 36M, 36C, 36K Laser beam projector
37Y Lubricant scraping member
41 photoconductor
42 Charger
43 Developer
44 Cleaning device
45 Cleaning blade
47A, 47B, 47C, 47D Lubricant supply device
100 Image forming apparatus

Claims (4)

They are arranged in series along the moving direction of the transfer body, and a plurality of image forming units, each provided with an image bearing member, the toner image formed on the image bearing member of the image forming unit to the transfer member An image forming apparatus comprising: a first transfer unit that transfers; and a second transfer unit that transfers a toner image transferred to the transfer body to a recording medium.
A first lubricating agent supply means for supplying a lubricant to the surface before Kiten Utsushitai,
Second lubricant supply means for re-supplying the lubricant supplied to the surface of the transfer body by the first lubricant supply means to the image carriers of the plurality of image forming units ;
Control means for controlling the second lubricant supply means,
When the portion of the transfer body, to which the lubricant is supplied by the first lubricant supply means, reaches a position facing each of the image carriers of the plurality of image forming units, the control means while controlled to substantially uniformly resupply is supplied to the surface lubricant to each image carrier, if the image transfer of a particular image forming units was reduced, the image bearing before Symbol specific image forming units image forming apparatus and controls such that only resupplying lubricant to the body.   The image forming apparatus according to claim 1, wherein the control unit adjusts a supply amount of the lubricant that is resupplied by controlling a pressing force that presses the transfer member against the image carrier.   The image forming apparatus according to claim 1, wherein the control unit adjusts a supply amount of the lubricant that is resupplied by controlling an electric field applied between the transfer member and the image carrier. . A plurality of image forming units that are arranged in series along the moving direction of the transfer body, each having an image carrier, and a toner image formed on the image carrier of each image forming unit are transferred to the transfer body. An image forming apparatus comprising: a first transfer unit that transfers; and a second transfer unit that transfers a toner image transferred to the transfer body to a recording medium.
First lubricant supply means for supplying a lubricant to the surface of the transfer member;
Second lubricant supply means for re-supplying the lubricant supplied to the surface of the transfer body by the first lubricant supply means to the image carriers of the plurality of image forming units;
By scraping off a part of the lubricant resupplied to each image carrier by the second lubricant supply means, the amount of lubricant finally resupplied to each image carrier is substantially uniform. Lubricant scraping means to adjust to become,
An image forming apparatus comprising:

Images