JP2015087400A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent filming of attachments such as toner on the surface of an intermediate transfer body and adhesion of powder shaved from the surface of a photoreceptor to the surface of the intermediate transfer body, in an image forming apparatus in which a toner image formed on the surface of a rotationally driven photoreceptor is transferred to the surface of the intermediate transfer body coming into contact with the photoreceptor and rotationally driven.SOLUTION: In an image forming apparatus 1 in which the toner image formed on the surface of a rotationally driven photoreceptor 10 is transferred to the surface of an intermediate transfer body 15 that comes into contact with the photoreceptor and is rotationally driven, the photoreceptor whose surface hardness is lower than the surface hardness of the intermediate transfer body is used and a speed difference in moving speed between the photoreceptor and the intermediate transfer body is increased by moving speed control means 30 for controlling the moving speed of the photoreceptor and the intermediate transfer body, based on durability information on the depletion state of the photoreceptor and a filming state in the intermediate transfer body.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these. In particular, in an image forming apparatus that transfers a toner image formed on the surface of a rotationally driven photoreceptor to a surface of an intermediate transfer body that is rotationally driven in contact with the photoreceptor, toner or the like is applied to the surface of the intermediate transfer body. Characteristically, it prevents deposits from being deposited on the surface of the intermediate transfer member by the intermediate transfer member that is rotated and driven in contact with the photosensitive member. It is what has.

  Conventionally, as an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a complex machine of these, the surface of a rotationally driven photoconductor is charged by a charging device, and the surface of the charged photoconductor is formed by a latent image forming device. Exposure is performed in accordance with image information to form an electrostatic latent image on the surface of the photoconductor, and toner is supplied to the electrostatic latent image formed on the surface of the photoconductor by a developing device so that the toner is applied to the surface of the photoconductor. After forming an image and transferring the toner image formed on the surface of the photoreceptor in this way onto the surface of an intermediate transfer body such as an intermediate transfer belt that is driven to rotate in contact with the photoreceptor, the intermediate transfer body A toner image transferred on the surface is transferred to a recording sheet.

  In such an image forming apparatus, the toner image formed on the surface of the photosensitive member as described above is transferred to the surface of the intermediate transfer member, and the toner image transferred to the surface of the intermediate transfer member is recorded on the recording sheet. When the toner is transferred to the intermediate transfer member, the toner or other residue remaining on the surface of the intermediate transfer member is gradually accumulated and filmed on the surface of the intermediate transfer member. There is a problem in that the toner image is not properly transferred to the recording sheet, and image noise such as white stripes occurs in the formed image.

  For this reason, conventionally, the moving speed of the photosensitive member and the moving speed of the intermediate transfer member are made different from each other, and filming is performed on the surface of the intermediate transfer member by the photosensitive member that is driven to rotate in contact with the intermediate transfer member. Residues such as toner are removed by rubbing to prevent image noise such as white streaks from being generated in the formed image.

  Here, in the case where the residual material such as toner filmed on the surface of the intermediate transfer member by the photosensitive member is rubbed and removed, the photosensitive layer on the surface of the photosensitive member is worn and the life of the photosensitive member is removed. In general, a protective layer or the like is provided on the surface of the photoconductor, and the surface hardness of the photoconductor is higher than the surface hardness of the intermediate transfer body to improve the wear resistance of the photoconductor surface. It was like that.

  However, when the surface hardness of the photoconductor is increased to increase the wear resistance in this way, when the surface of the photoconductor is charged by the charging device, the discharge product adhering to the surface of the photoconductor is removed from the photoconductor. It is difficult to remove the surface by a cleaning device that cleans the surface of the image, and there is a problem that when an image is formed in a high-temperature and high-humidity environment, image flow occurs in the formed image.

  For this reason, the surface hardness of the photosensitive member is made lower than the surface hardness of the intermediate transfer member so that discharge products adhering to the surface of the photosensitive member can be removed by a cleaning device or the like, and the photosensitive layer on the surface of the photosensitive member It is conceivable to increase the lifetime of the photoreceptor by increasing the film thickness of the photosensitive member.

  However, when image formation is performed with the surface hardness of the photoreceptor lower than the surface hardness of the intermediate transfer member, image noise such as white spots occurs in the formed image.

  Conventionally, as disclosed in Patent Document 1, a friction roller for polishing the surface of the photosensitive member and a friction resistance value detecting means for detecting a frictional resistance value on the surface of the photosensitive member are provided to detect the frictional resistance value. When a value larger than a predetermined frictional resistance value is detected by the means, the rotation ratio of the rubbing roller to the photoconductor is changed, and the polishing performance of the rubbing roller on the surface of the photoconductor is improved, so that the surface of the photoconductor is There has been proposed one that removes the attached discharge products and the like.

  However, in the technique disclosed in Patent Document 1, in order to remove discharge products and the like attached to the surface of the photoconductor, a friction roller for polishing the surface of the photoconductor and a frictional resistance value on the surface of the photoconductor are detected. It is necessary to provide a frictional resistance value detecting means, and the cost is high, and the rubbing roller is disposed around the photoconductor in order to rotate the rubbing roller in contact with the photoconductor. As a result, it is necessary to secure a sufficient space, and there is a problem that the apparatus becomes larger.

  In addition, in the device disclosed in Patent Document 1, as described above, residues such as toner remaining on the surface of the intermediate transfer member are gradually accumulated and prevented from being filmed on the surface of the intermediate transfer member. However, there is no indication of removing discharge products and the like adhering to the surface of the photoreceptor, and these problems cannot be solved at the same time.

JP 2010-60679 A

  In the present invention, as described above, the moving speed of the photosensitive member and the moving speed of the intermediate transfer member are made different, and the surface of the intermediate transfer member is filmed by the photosensitive member that is rotationally driven in contact with the intermediate transfer member. In addition to removing residual toner and the like, the surface hardness of the photosensitive member is made lower than the surface hardness of the intermediate transfer member, and discharge products adhering to the surface of the photosensitive member are removed by a cleaning device or the like. In such a case, it is an object to prevent image noise such as white spots from occurring in the formed image.

  Here, as a result of examining the cause of image noise such as white spots in the formed image when the surface hardness of the photoreceptor is lower than the surface hardness of the intermediate transfer body as described above, the surface of the photoreceptor is Since the hardness is lower than the surface hardness of the intermediate transfer member, the residual material such as toner filmed on the surface of the intermediate transfer member is rubbed by the photosensitive member rotated and driven in contact with the intermediate transfer member as described above. This is probably because part of the surface of the photoconductor was scraped by the intermediate transfer member to generate powder, and this powder adhered to the surface of the intermediate transfer member.

  In the present invention, the moving speed of the photosensitive member and the moving speed of the intermediate transfer member are made different, and filming is performed on the surface of the intermediate transfer member by the photosensitive member that is driven to rotate in contact with the intermediate transfer member. Even when the surface hardness of the photoconductor is lower than the surface hardness of the intermediate transfer member, the film on the surface of the intermediate transfer member is rotated by the photoconductor rotated as described above. When removing residual toner such as toner by rubbing, the surface of the photoreceptor is prevented from being scraped by the intermediate transfer member to generate powder, and white spots and the like are formed on the formed image. The object is to prevent the occurrence of image noise.

  In the image forming apparatus according to the present invention, in order to solve the above-described problem, the toner image formed on the surface of the photosensitive member that is rotationally driven is applied to the surface of the intermediate transfer member that is rotationally driven in contact with the photosensitive member. In the image forming apparatus to be transferred, a photosensitive member whose surface hardness is lower than the surface hardness of the intermediate transfer member is used, and a moving speed control means for controlling the moving speed of the photosensitive member and / or the intermediate transfer member is provided. Based on the endurance information on the depleted state of the photosensitive member and / or the filming state of the intermediate transfer member, the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member is increased by the moving speed control means.

  Here, in the initial state of the photoconductor and the intermediate transfer body, the surface of the photoconductor and the intermediate transfer body are less worn, and the adhesion of the residue such as toner on the surface of the intermediate transfer body is also small. Even if the speed difference is small, no residue such as toner is filmed on the surface of the intermediate transfer member, and if the speed difference in the moving speed of the photosensitive member and the intermediate transfer member is small, the intermediate transfer as described above. Even when a photoconductor having a surface hardness lower than the surface hardness of the transfer body is used, a part of the surface of the photoconductor is hardly scraped by the intermediate transfer body to generate powder. Then, based on the endurance information on the depleted state of the photoconductor and / or the filming state in the intermediate transfer body, if the speed difference between the photoconductor and the intermediate transfer body is increased by the above moving speed control means, Even if toner or other residue is accumulated on the surface of the intermediate transfer member, the toner or other residue adhering to the surface of the intermediate transfer member is caused by the difference in moving speed between the photosensitive member and the intermediate transfer member. Since the surface of the photoconductor is worn due to durability while being appropriately rubbed and removed by the photoconductor driven to rotate in contact with the surface, the contact between the photoconductor and the intermediate transfer body Even if the pressure is decreased and the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member is increased, the surface of the photosensitive member is prevented from being scraped by the intermediate transfer member to generate powder.

  Further, on the basis of the durability information regarding the depletion state of the photosensitive member and / or the filming state of the intermediate transfer member as described above, the moving speed control means increases the difference in moving speed between the photosensitive member and the intermediate transfer member. The moving speed control means preferably controls the timing for increasing the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member and the rate of increasing the speed difference.

  The durability information on the depleted state of the photosensitive member includes charging conditions such as a charging voltage and a charging voltage frequency in a charging device for charging the photosensitive member, which are considered to affect the wear of the photosensitive member, and the photosensitive member. It is possible to refer to the moving distance of the surface. When a charging roller that contacts the surface of the photosensitive member and charges the photosensitive member is used as the charging device, the influence of the charging voltage and the frequency of the charging voltage is increased.

  Further, the durability information regarding the filming state in the intermediate transfer member includes the area ratio of the toner image to the intermediate transfer member, the environmental conditions such as temperature and humidity, and the intermediate transfer, which are considered to affect the filming in the intermediate transfer member. The moving distance of the body surface can be referred to.

  In the image forming apparatus, an endless intermediate transfer belt that is rotationally driven is used as the intermediate transfer member, and the intermediate transfer belt is pressed against the surfaces of a plurality of photoconductors by primary transfer rollers. A toner image formed on the surface of each photoreceptor can be transferred onto the surface of the intermediate transfer belt. In this case, it is troublesome to change the moving speed of each photoconductor to control the speed difference between the moving speed of the photoconductor and the intermediate transfer body. It is preferable to control the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member by changing the moving speed.

  In the image forming apparatus of the present invention, as described above, based on the durability information on the depleted state of the photosensitive member and the filming state of the intermediate transfer member, the moving speed control means causes the moving speed of the photosensitive member and the intermediate transfer member. Since the difference is increased, even if toner residue is accumulated on the surface of the intermediate transfer member due to durability, the toner residue remaining on the surface of the intermediate transfer member contacts the surface of the intermediate transfer member. Then, the toner is properly rubbed and removed by the rotationally driven photoconductor, and the residue such as toner adhering to the surface of the intermediate transfer member is filmed, and the image such as white streaks is formed on the formed image. Generation of noise is prevented.

  Even when a photoconductor having a lower surface hardness than that of the intermediate transfer member is used as described above, there is little difference in the moving speed between the photoconductor and the intermediate transfer member in the initial stage. The surface of the photoconductor is less likely to be scraped off by the intermediate transfer member and powder is generated, and the surface of the photoconductor is worn at the stage where printing durability has advanced. Even if the contact pressure between the photosensitive member decreases and the speed difference between the photosensitive member and the intermediate transfer member increases, the surface of the photosensitive member is prevented from being scraped by the intermediate transfer member and generating powder. Generation of image noise such as white spots on the formed image is prevented.

1 is a schematic explanatory diagram illustrating a state in which image formation is performed using an image forming apparatus according to an embodiment of the present invention. In the image forming apparatus according to the above-described embodiment, a state in which an intermediate transfer member composed of an intermediate transfer belt is brought into contact with the surface of the photosensitive member with a predetermined contact pressure by a primary transfer roller is shown, (A) is viewed from the front side. Schematic explanatory drawing, (B) is a schematic explanatory drawing seen from the side. In the image forming apparatus according to the above-described embodiment, the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member is controlled by the moving speed control unit based on the durability information regarding the depleted state of the photosensitive member and the filming state of the intermediate transfer member. It is the schematic explanatory drawing which showed the state to do. In the image forming apparatus according to the above-described embodiment, the speed at which white spots occur in relation to the speed difference | va−vb | between the moving speed va of the photosensitive member and the moving speed vb of the intermediate transfer member, and the number of images formed. It is the graph which showed that the appropriate area | region exists between the white spot limit line of difference | va-vb |, and the white stripe limit line of speed difference | va-vb | which a white stripe generate | occur | produces.

  Next, an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Based on experimental examples, the image forming apparatus according to the present invention has white streaks or the like even during durability. It is clarified that generation of image noise and image noise such as white spots are prevented. Note that the image forming apparatus according to the present invention is not limited to those shown in the following embodiments, and can be implemented with appropriate modifications within a range not changing the gist thereof.

  In the image forming apparatus 1 in this embodiment, as shown in FIG. 1, four photoconductors 10 are provided therein, and charging rollers 11 are used as charging devices 11 for charging the surface of each photoconductor 10. The four developing devices 13 that are provided so as to be in contact with the surface of the image sensor 10 and that contain a developer containing toner and a carrier are provided corresponding to the respective photoconductors 10. The color of the toner in the agent is made different so that black, yellow, magenta, and cyan toners are used.

  Then, each of the photoconductors 10 is rotated, and a predetermined charging bias voltage is applied to the charging roller 11 from a charging power source (not shown). The surface of each photoconductor 10 charged in this way is exposed according to the image formation information by the latent image forming device 12, and the surface of each photoconductor 10 according to the image formation information. An electrostatic latent image is formed.

  Next, for each photoconductor 10 on which the electrostatic latent image is formed in this manner, a toner of a predetermined color is supplied from the corresponding developing device 13 to the electrostatic latent image on each photoconductor 10 and development is performed. A toner image of each color is formed on the surface of each photoconductor 10.

  Then, an intermediate transfer composed of an endless intermediate transfer belt 15 that is driven to rotate around a driving roller 14a and a rotating roller 14b on the surface of each photoconductor 10 on which a toner image of each color is formed as described above. The body 15 is brought into contact with the primary transfer roller 16 at a predetermined contact pressure, and each color toner image formed on the surface of each photoconductor 10 is transferred onto the surface of the intermediate transfer body 15 that is rotationally driven. The toner image is sequentially transferred by the transfer roller 16 in order to form a toner image in which the toner images of the respective colors are combined on the surface of the intermediate transfer body 15. Further, residual toner such as toner remaining on the surface of each photoconductor 10 without being transferred to the intermediate transfer body 15 is removed from each photoconductor 10 by a cleaning blade 17 a provided in the first cleaning device 17. It is removed from the surface.

  The toner image formed on the intermediate transfer member 15 as described above is guided to a position facing the secondary transfer roller 18 by the intermediate transfer member 15.

  On the other hand, the recording sheet S accommodated in the lower part of the image forming apparatus 1 is fed by a sheet feeding roller 19 and sent to a timing roller 20, and the recording sheet S is fed to the intermediate transfer body 15 and a secondary transfer roller by the timing roller 20. 18, the toner image formed on the surface of the intermediate transfer member 15 is transferred to the recording sheet S by the secondary transfer roller 18. Further, a toner or other residue that is not transferred to the recording sheet S and remains on the surface of the intermediate transfer member 15 is removed from the surface of the intermediate transfer member 15 by the cleaning blade 21 a provided in the second cleaning device 21. I am doing so.

  Then, the recording sheet S on which the toner image is transferred as described above is guided to the fixing device 22, and the toner image thus transferred is fixed on the recording sheet S by the fixing device 22. The recording sheet S on which is fixed is discharged by a discharge roller 23.

  Here, in the image forming apparatus 1, the photoconductor 10 having a surface hardness lower than the surface hardness of the intermediate transfer body 15 is used.

  In this embodiment, as shown in FIGS. 2A and 2B, when the intermediate transfer member 15 is brought into contact with the surface of the photoconductor 10 with the primary transfer roller 16 at a predetermined contact pressure as described above. Further, the positioning rollers 16b provided at both ends of the shaft 16a of the primary transfer roller 16 are brought into contact with the upper surface of the housing 24 such as the photoconductor 10 and the first cleaning device 17, so that the primary transfer roller 16 is moved to the photoconductor. The intermediate transfer member 15 is set at a position shifted from the top of the intermediate member 15 so that the intermediate transfer member 15 has an appropriate biting amount x with respect to the photosensitive member 10, and the intermediate transfer member 15 brought into contact with the surface of the photosensitive member 10 by the biting amount x. The contact pressure is adjusted.

  In this embodiment, the speed difference between the moving speed va of the photoconductor 10 and the moving speed vb of the intermediate transfer body 15 is controlled by controlling the moving speed va of the photoconductor 10 and the moving speed vb of the intermediate transfer body 15. In adjusting va−vb |, as shown in FIG. 3, the moving speed control means 30 changes the rotational speed of the driving roller 14 a to change the moving speed vb of the intermediate transfer member 15. Yes.

  Here, the moving speed control means 30 changes the moving speed of the intermediate transfer member 15 to adjust the speed difference | va−vb | between the moving speed va of the photosensitive member 10 and the moving speed vb of the intermediate transfer member 15. In performing the charging, the first durability information storage unit 31 that stores the durability information regarding the depletion state of the photoconductor 10 is used to set the charging condition such as the voltage value and the frequency of the charging bias voltage applied to the charging roller 11. Information on the charging condition is output from the condition setting unit 31a, and information on the movement distance of the surface of the photoconductor 10 is output from the photoconductor surface movement distance calculation unit 31b that calculates the movement distance of the surface of the photoconductor 10.

  In addition, the second endurance information storage unit 32 that stores endurance information regarding the filming state in the intermediate transfer body 15 is changed from the area ratio calculation unit 32a that calculates the area ratio of the toner image to the intermediate transfer body 15 to the intermediate transfer body 15. Information on the toner image area ratio, information on the environmental condition consisting of temperature and humidity from the environmental condition detection means 32b for detecting the environmental condition consisting of temperature and humidity, and intermediate transfer for calculating the moving distance of the surface of the intermediate transfer body 15 Information on the movement distance of the surface of the intermediate transfer body 15 is output from the body surface movement distance calculation means 32c.

  Then, endurance information on the depletion state of the photoconductor 10 is output from the first endurance information storage unit 31 to the moving speed control unit 30, and the intermediate transfer member is output from the second endurance information storage unit 32. 15 is output, and the rotation speed of the driving roller 14a is changed by the moving speed control means 30 as described above based on the durability information, and the moving speed vb of the intermediate transfer body 15 is changed. As the endurance progresses, the speed difference | va−vb | between the moving speed va of the photosensitive member 10 and the moving speed vb of the intermediate transfer member 15 is increased at an appropriate rate at an appropriate timing. Residues such as toner adhering to the surface of the body 15 are removed by the photoconductor 10 that is driven to rotate in contact with the surface of the intermediate transfer body 15 and attached to the surface of the intermediate transfer body 15. In addition to preventing the residual toner and the like from being filmed, a part of the surface of the photoconductor 10 having a surface hardness lower than the surface hardness of the intermediate transfer member 15 is scraped by the intermediate transfer member 15 to generate powder. It prevents it from occurring.

  Here, as described above, the photosensitive member 10 having a surface hardness lower than the surface hardness of the intermediate transfer member 15 is used, and the initial biting amount x of the intermediate transfer member 15 with respect to the photosensitive member 10 is set to a predetermined value. When the surface 10 and the surface of the intermediate transfer member 15 are brought into contact with each other at a predetermined contact pressure, as shown in FIG. 4, at the initial stage of image formation, the moving speed va of the photosensitive member 10 and the intermediate transfer member When the speed difference | va-vb | with respect to the moving speed vb of 15 becomes larger than a predetermined value, a part of the surface of the photoconductor 10 is scraped by the intermediate transfer body 15 to generate powder on the intermediate transfer body 15. Although white spots occur in an image formed by adhering to the surface, if the number of images formed increases and the surface of the photoconductor 10 is worn, the amount x of the intermediate transfer member 15 biting into the photoconductor 10 becomes small. The surface of the photoreceptor 10 and the intermediate transfer member 5, even if the speed difference | va−vb | is increased within a predetermined range, the surface of the photoconductor 10 is prevented from being scraped and white spots are generated. The white spot limit line of the speed difference | va−vb | at which the dots are generated increases as the number of images formed increases.

  On the other hand, in the initial stage of image formation, since no residue such as toner adheres to the surface of the intermediate transfer member 15, the speed difference between the moving speed va of the photosensitive member 10 and the moving speed vb of the intermediate transfer member 15. Even if | va−vb | is small, a residue such as toner adhering to the surface of the intermediate transfer member 15 is not filmed and white streaks are not generated in the formed image. In the case where the residue such as toner adheres and accumulates on the surface of the intermediate transfer body 15 by increasing, the speed difference | va−vb | is increased to adhere to the surface of the intermediate transfer body 15. If residuals such as toner are not removed by the rotationally driven photoconductor 10, white stripes are generated in the formed image. Therefore, the white stripe limit line of the speed difference | va−vb | It increases as the number of sheets increases. Further, when the number of image formations is further increased, a residue such as toner adheres to the surface of the intermediate transfer member 15 to some extent, and the amount of residual toner such as toner newly attached to the surface of the intermediate transfer member 15 When the amount of residual toner such as toner removed from the surface of the intermediate transfer member 15 by the cleaning device 21 of FIG. 2 is balanced, the white stripe limit line of the speed difference | va−vb | The speed difference | va−vb | is maintained.

  In this embodiment, the white spot generation area defined by the white spot limit line shown in FIG. 4 and the white stripe generation area defined by the white stripe limit line are appropriate areas. The speed difference | va−vb | between the moving speed va of the photoconductor 10 and the moving speed vb of the intermediate transfer body 15 is increased at an appropriate rate at an appropriate timing. .

  As a result, toner or other residue adhering to the surface of the intermediate transfer member 15 is filmed, and image noise such as white streaks is generated in the formed image, or powder scraped from the surface of the photosensitive member. Is prevented from adhering to the intermediate transfer member 15 and generating image noise such as white spots on the formed image.

  Next, based on a specific experimental example, when the surface hardness of the photoconductor 10 is lower than the surface hardness of the intermediate transfer body 15, the movement speed va of the photoconductor 10 and the movement speed vb of the intermediate transfer body 15 are calculated. When the speed difference | va−vb | is increased at an appropriate timing, it is possible to prevent the residue such as toner adhering to the surface of the intermediate transfer member 15 from being filmed and It will be clarified that it is possible to prevent a part from being scraped by the intermediate transfer member 15 and generating powder. In the following experimental examples, the moving speed vb of the intermediate transfer body 15 is changed as described above, and the speed difference | va−vb between the moving speed va of the photoconductor 10 and the moving speed vb of the intermediate transfer body 15. The speed difference | va−vb | between the two is expressed by a speed ratio θ (vb / va) of the moving speed vb of the intermediate transfer member 15 to the moving speed va of the photosensitive member.

The surface hardness of the photosensitive member 10 and the intermediate transfer member 15 is an ultra-small hardness meter H-100V (manufactured by Fischer Instruments), a Vickers indenter is used as a measurement indenter, and environmental conditions are 20 ° C. and 60%. Universal hardness [N / mm ² ] is measured under the measurement conditions of RH, maximum test load of 2 mN, load speed of 2 mN / 10 seconds, maximum load creep time of 5 seconds, and unloading speed of 2 mN / 10 seconds. Measurement was performed at 5 points and 5 points randomly in the circumferential direction, for a total of 25 points, and the average value was shown as the surface hardness of the photosensitive member 10 and the intermediate transfer member 15.

(Experiment 1)
In Experiment 1, the amount x of the intermediate transfer member with respect to the photosensitive member is set to 0.15 mm, and the speed ratio θ (= vb / va) of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member is set to 1. .06, a plurality of photoconductors having different surface hardness and an intermediate transfer member are combined as shown in Table 1 to form images, and in the formed image, white spots based on the photoconductor shavings are formed. The points were evaluated and the results are shown in Table 1. Regarding the evaluation of white spots, the case where no white spots occurred was indicated by ◯, the case where white spots were generated was indicated by ×, and the case where white spots were markedly generated was indicated by XX.

  As a result, under the conditions of the biting amount x and the speed ratio θ, when the surface hardness of the intermediate transfer member is higher than the surface hardness of the photosensitive member, the photosensitive member is scraped to the intermediate transfer member and white spots are generated. I understand that.

(Experiment 2)
In Experiment 2, a plurality of intermediate transfer members each having a surface hardness of the intermediate transfer member higher than that of the photosensitive member and a photosensitive member are used in combination as shown in Tables 2 to 4 below. Is set to 0.10 mm, 0.15 mm, and 0.20 mm, the speed ratio θ (= vb / va) of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member, respectively. In the same manner as described above, the white spots in the formed image are evaluated, and the results when the bite amount x is 0.10 mm are shown in Table 2, and the bite amount x Table 3 shows the results when 0.15 mm is set to 0.15 mm, and Table 4 shows the results when bite amount x is 0.20 mm.

  As a result, even when the surface hardness of the intermediate transfer member is higher than the surface hardness of the photosensitive member, the intermediate transfer member with respect to the moving speed va of the photosensitive member or when the biting amount x of the intermediate transfer member with respect to the photosensitive member is reduced. It can be seen that when the speed ratio θ of the moving speed vb is reduced, the occurrence of white spots is suppressed.

(Experiment 3)
In Experiment 3, an intermediate transfer member having a surface hardness of 200 N / mm ^{2 and} a photosensitive member having a surface hardness of 180 N / mm ² lower than the surface hardness of the intermediate transfer member were used. The initial biting amount x is set to 0.15 mm, and the speed ratio θ (= vb / va) of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member is set as shown in Tables 5 and 6 below. In each image, a printing durability test was performed, and in the image when a predetermined number of images were formed, the occurrence of white streaks due to filming on the intermediate transfer member and the occurrence of white spots due to photoconductor scraping were examined. It was.

  Table 5 shows the results of examining the occurrence state of white streaks in the image when the predetermined number of images were formed, and Table 6 shows the result of examining the occurrence state of white spots. In Table 5, when white streaks did not occur, ○, when white streaks occurred, indicated by ×, and in Table 6, when white spots did not occur, ○, white spots occurred The case where it did is shown by x.

  As a result, with respect to white streaks based on filming on the intermediate transfer member, no white streak occurs when the speed ratio θ of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member is 1.06 or more. However, when the speed ratio θ was 1.03 or less, white streaks occurred due to an increase in the number of printing sheets. This is because when the speed ratio θ is 1.03 or less and the speed difference | va−vb | between the moving speed va of the photosensitive member and the moving speed vb of the intermediate transfer member is small, it adheres to the surface of the intermediate transfer member. Residue such as toner that cannot be removed by appropriately rubbing with a photoreceptor that is driven to rotate in contact with the surface of the intermediate transfer member, and remains on the surface of the intermediate transfer member. This is probably because the film was accumulated and filmed.

  Further, with respect to white spots based on the photoconductor shaving, white spots did not occur when the speed ratio θ of the moving speed vb of the intermediate transfer member to the moving speed va of the photoconductor was 1.03 or less. When the ratio θ is 1.06 or more and the speed difference | va−vb | between the moving speed va of the photosensitive member and the moving speed vb of the intermediate transfer member becomes large, white spots are generated as described above. Even when the speed ratio θ is 1.06 or more, the occurrence of white spots is suppressed as the number of printing durability increases. This is because the surface of the photosensitive member is gradually worn with the increase in the number of printing durability, and the amount x of the intermediate transfer member with respect to the photosensitive member is gradually reduced, so that the contact of the intermediate transfer member that is in contact with the surface of the photosensitive member. This is probably because the pressure decreased.

(Experiment 4)
Also in Experiment 4, the durability of the intermediate transfer member in terms of the filming state using an intermediate transfer member having a surface hardness of 200 N / mm ^{2 and} a photosensitive member having a surface hardness of 180 N / mm ² lower than the surface hardness of the intermediate transfer member. As information, the area ratio of the toner image to the intermediate transfer body, which is considered to affect the filming on the intermediate transfer body, the temperature, the humidity, and the movement distance of the surface of the intermediate transfer body are referred to.

Here, in this experiment, the filming value was obtained by the following equation.
Filming value = area ratio of toner image to intermediate transfer member (%) × temperature (° C.) × humidity (%) × movement distance of intermediate transfer member surface (m) ÷ 10000

  Then, the filming integrated value obtained by calculating and integrating the filming value for each image formation is used as the durability information regarding the filming state in the intermediate transfer member.

  The initial biting amount x of the intermediate transfer member with respect to the photosensitive member is set to 0.15 mm, and the speed ratio θ (= vb / va) of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member is shown in the following table. 7 and Table 8 are set, and a printing durability test is performed. In the image at the time when the integrated filming value reaches a predetermined value, white streaks are generated due to filming on the intermediate transfer member. The state of occurrence of white spots based on the state and shaving of the photoreceptor was examined.

  Table 7 shows the results of examining the occurrence state of white streaks and Table 7 shows the result of occurrence of white spots in the image when the filming integrated value reaches a predetermined value. In Table 7, the case where white streaks did not occur was indicated by ○, and the case where white streaks occurred was indicated by ×, and in Table 8, when white spots did not occur, ○, white spots were generated. Cases are indicated by x.

  Here, from the results shown in Table 7 and Table 8, the speed ratio θ between the initial filming integrated value up to 3000 is set to 1.03, and the filming integrated value exceeds 3000 to 4000 speed ratio. When θ is increased to 1.06, and the speed ratio θ when the integrated filming value exceeds 4000 is increased to 1.09, white streaks based on filming of the residue on the intermediate transfer member are increased. It can be seen that a good image can be obtained without the occurrence of white spots due to the occurrence and the shaving of the photoreceptor.

(Experiment 5)
Also in Experiment 5, as an endurance information on the depletion state of the photoreceptor, an intermediate transfer body having a surface hardness of 200 N / mm ² and a photoreceptor having a surface hardness of 180 N / mm ² lower than the surface hardness of the intermediate transfer body are used. The peak-to-peak value (Vpp) of the charging bias voltage applied to the charging roller, which is considered to affect the wear of the photosensitive member, the frequency thereof, and the moving distance of the photosensitive member surface are referred to.

Here, in this experiment, the photoreceptor depletion value was determined by the following equation.
Photoconductor depletion value = peak-peak value (V) of charging bias voltage × frequency of charging bias voltage (kHz) × movement distance of photosensitive member surface (m) ÷ 10

  Then, the photoconductor depletion integrated value obtained by calculating and integrating the photoconductor depletion value for each image formation is used as durability information regarding the photoconductor depletion state.

  The initial biting amount x of the intermediate transfer member with respect to the photosensitive member is set to 0.15 mm, and the speed ratio θ (= vb / va) of the moving speed vb of the intermediate transfer member to the moving speed va of the photosensitive member is shown in the following table. No. 9 and Table 10 were set, and a printing durability test was performed. In the image at the time when the photosensitive member depletion integrated value reached a predetermined value, white streaks based on filming on the intermediate transfer member were detected. The state of occurrence of white spots based on the state of occurrence and shaving of the photoreceptor was examined.

  Table 9 shows the results of examining the occurrence state of white spots and Table 10 shows the result of examining the occurrence state of white stripes in the image when the photosensitive member depletion integrated value reaches a predetermined value. In Table 9, when white spots did not occur, ◯, when white spots occurred, x, and in Table 10, when white streaks did not, white, white streaks occurred Cases are indicated by x.

  Here, from the results shown in Tables 9 and 10, the speed ratio θ between the initial value and the accumulated photoconductor wear value of 700 is set to 1.03, and the accumulated photoconductor wear value exceeds 700 to 2100. When the speed ratio θ is increased to 1.06, and the speed ratio θ when the photosensitive member depletion integrated value exceeds 2100 is increased to 1.09, generation of white spots due to the shaving of the photosensitive member and intermediate It can be seen that a good image without white streaks due to filming of the residue on the transfer body can be obtained.

  In the experiments 4 and 5, the durability information regarding the filming state of the intermediate transfer member and the durability information regarding the depletion state of the photosensitive member are individually determined, and the intermediate transfer member is detected with respect to the moving speed va of the photosensitive member. Although the speed ratio θ of the moving speed vb is controlled, both the durability information related to the filming state in the intermediate transfer member and the durability information related to the depleted state of the photosensitive member are determined, and the photosensitive member moving speed va is determined. It is also possible to control the speed ratio θ of the moving speed vb of the intermediate transfer member.

DESCRIPTION OF SYMBOLS 1 Device main body 10 Photoconductor 11 Charging roller (charging device)
12 Latent image forming device 13 Developing device 14a Driving roller, 14b Rotating roller 15 Intermediate transfer member (intermediate transfer belt)
16 Primary transfer roller, 16a shaft, 16b Positioning roller 17 First cleaning device, 17a Cleaning blade 18 Secondary transfer roller 19 Feed roller 20 Timing roller 21 Second cleaning device, 21a Cleaning blade 22 Fixing device 23 Paper discharge roller 24 Housing 30 Movement speed control means 31 First durability information storage means, 31a Charging condition setting means, 31b Photoconductor surface movement distance calculation means 32 Second durability information storage means, 32a Area ratio calculation means, 32b Environmental condition detection means, 32c Intermediate transfer member surface moving distance calculating means S Recording sheet va Photoconductor moving speed, vb Intermediate transfer member moving speed x Biting amount

Claims (6)

  In an image forming apparatus for transferring a toner image formed on the surface of a rotationally driven photoreceptor to a surface of an intermediate transfer body that is rotationally driven in contact with the photoreceptor, the surface is more than the surface hardness of the intermediate transfer body. In addition to using a photoconductor with low hardness, a moving speed control means for controlling the moving speed of the photoconductor and / or the intermediate transfer member is provided, and durability information on the depleted state of the photoconductor and / or the filming state on the intermediate transfer member is provided. On the basis of the above, the moving speed control means increases the speed difference between the moving speeds of the photosensitive member and the intermediate transfer member.   2. The image forming apparatus according to claim 1, wherein the moving speed control unit controls a timing for increasing a speed difference between moving speeds of the photosensitive member and the intermediate transfer member and a rate of increasing the speed difference. Image forming apparatus.   3. The image forming apparatus according to claim 1, wherein the durability information relating to the depleted state of the photosensitive member refers to a charging condition in the charging device for charging the photosensitive member and a moving distance of the surface of the photosensitive member. An image forming apparatus.   4. The image forming apparatus according to claim 3, wherein a charging roller is used as the charging device.   5. The image forming apparatus according to claim 1, wherein the area ratio of the toner image to the intermediate transfer member, the environmental condition, and the surface of the intermediate transfer member are used as the durability information regarding the filming state in the intermediate transfer member. An image forming apparatus characterized by referring to a moving distance of the image forming apparatus.   6. The image forming apparatus according to claim 1, wherein an endless intermediate transfer belt that is rotationally driven is used as the intermediate transfer member, and the intermediate transfer belt is used as a plurality of photosensitive members. An image forming apparatus characterized in that the toner image formed on the surface of each photoconductor is transferred onto the surface of the intermediate transfer belt by being pressed against the surface of the toner by a primary transfer roller.

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