JP6672723B2 - Image forming apparatus, control method, and control program - Google Patents

Description

  The present disclosure relates to control of an image forming apparatus, and particularly to control of an electrophotographic image forming apparatus.

  Electrophotographic image forming apparatuses have become widespread. An electrophotographic image forming apparatus includes, as a printing process, a process of uniformly charging a photoconductor, a process of exposing the photoconductor to form an electrostatic latent image, and a process of forming an electrostatic latent image on the photoconductor into toner. A step of developing as an image, a step of transferring the toner image on the photoconductor to the intermediate transfer body, and a step of transferring the toner image on the intermediate transfer body to paper are executed.

  In the transferring step, the photoconductor and the intermediate transfer member rotate while being in contact with each other, and the image forming apparatus applies a voltage having a polarity opposite to that of the toner image to the intermediate transfer member, so that the toner is transferred from the photoconductor to the intermediate transfer member. Transfer the image.

  Japanese Patent Application Laid-Open No. 2015-087400 (Patent Document 1) discloses a technique for controlling the rotation of a photoconductor and an intermediate transfer member. To prevent the powder shaved from the surface from adhering to the surface of the intermediate transfer member. " Japanese Patent Application Laid-Open No. 2012-173650 (Patent Literature 2) discloses an image forming apparatus that “understands the remaining life of a photoconductor and appropriately controls the relative speed difference between the peripheral speeds of the photoconductor and the intermediate transfer body in accordance with the remaining life”. Has been disclosed.

JP-A-2015-087400 JP 2012-173650 A

  The photoreceptor wears out as it is used. When the photoreceptor wears, the diameter of the photoreceptor becomes shorter, and a peripheral speed difference occurs between the photoreceptor and the intermediate transfer member. If there is a peripheral speed difference between the photosensitive member and the intermediate transfer member, the photosensitive member is damaged by friction with an external additive of the toner. Therefore, an image forming apparatus capable of suppressing an increase in the peripheral speed difference between the photoconductor and the intermediate transfer body is desired.

  The image forming apparatus disclosed in Patent Literature 1 removes a residue such as toner by increasing a speed difference between a photoconductor and an intermediate transfer body. In the image forming apparatus disclosed in Patent Document 2, when the life of the photoconductor is shortened, the relative speed difference between the photoconductor and the intermediate transfer body is increased, and the toner image is easily peeled off from the photoconductor. When the speed difference between the photosensitive member and the intermediate transfer member increases, as in the image forming apparatuses disclosed in Patent Documents 1 and 2, the pace at which the photosensitive member and the intermediate transfer member are worn increases.

  The present disclosure has been made in order to solve the above-described problems, and an object in one aspect is to provide an image forming apparatus capable of delaying the pace at which a photoreceptor is worn down compared to the related art. is there. It is another object of the present invention to provide a control method capable of delaying a wear rate of a photoreceptor as compared with the related art. It is still another object of the present invention to provide a control program capable of delaying a wear rate of a photoreceptor as compared with the related art.

According to a certain aspect, the image forming apparatus includes a plurality of image carriers each having an electrostatic latent image formed on a surface according to an input image, and the plurality of image carriers having the electrostatic latent image as a toner image. A plurality of developing devices for developing on the surface, respectively, a transfer member which rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred; A transfer unit for transferring the toner image transferred to the transfer body to the transfer medium, a detection unit for detecting a value correlated with the wear amount of the surface of each image carrier, and a detection unit for each of the image carriers. In accordance with a value correlated with the amount of wear of the surface, the peripheral speed difference between each of the image carriers and the transfer body is set to be smaller than the current peripheral speed difference. A control unit for individually controlling the speed. Wherein the control unit, you increase the degree of increasing the peripheral speed as said image bearing member is provided on the downstream side of the transfer member.

Preferably, the control unit maintains the peripheral speed of the transfer body, and increases the peripheral speed of each of the image carriers as the current peripheral speed increases as the value correlated with the amount of wear of the surface of each of the image carriers increases. you faster than.
Good Mashiku, said control unit, the peripheral speed difference between the said image bearing member and the transfer member, the smaller than the current peripheral speed difference first predetermined value or less and the first predetermined The peripheral speed of each of the image carriers is individually controlled so as to be equal to or more than a second predetermined value smaller than the value.

Preferably, the control unit obtains, from the peripheral speed information, a control value corresponding to a value correlated with the wear amount of the surface of each of the image carriers detected by the detection unit, based on the control value. individually controlling the peripheral speed of each said image bearing member, the peripheral speed information, the control values for the peripheral speed of each said image bearing member to be smaller than the current the peripheral speed difference, the the image carrier Is specified for each value correlated with the above-mentioned abrasion amount of the surface .

Preferably, the control of the rotation of each of the image carriers by the control unit is performed at a predetermined timing.

Preferably, the value correlated with the amount of wear of the surface of each image carrier is the number of rotations from the start of rotation of the image carrier to the present. The predetermined timing includes a timing at which the rotation speed reaches a predetermined rotation speed.

Preferably, the control of the rotation of each of the image carriers by the control unit is executed when a predetermined condition indicating that each of the image carriers is worn is satisfied.

According to another aspect, a method for controlling an image forming apparatus is provided. The image forming apparatus includes: a plurality of image carriers each having an electrostatic latent image formed on a surface according to an input image; and developing the electrostatic latent images as toner images on the surfaces of the plurality of image carriers. A plurality of developing devices, a transfer body that rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred; A transfer unit for transferring the obtained toner image to a transfer-receiving medium, wherein the control method includes a step of detecting a value correlated with a wear amount of a surface of each of the image carriers, and a step of detecting the value of each of the image carriers. The peripheral speed of each of the image carriers is set so that the peripheral speed difference between each of the image carriers and the transfer member is smaller than a first predetermined value in accordance with a value correlated with the surface wear amount. And individually controlling. In the step of individually controlling the peripheral speed of each said image bearing member, you increase the degree of increasing the peripheral speed as said image bearing member is provided on the downstream side of the transfer member.

According to yet another aspect, a control program for an image forming apparatus is provided. The image forming apparatus includes: a plurality of image carriers each having an electrostatic latent image formed on a surface according to an input image; and developing the electrostatic latent images as toner images on the surfaces of the plurality of image carriers. A plurality of developing devices, a transfer body that rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred; A transfer unit for transferring the toner image to the transfer medium, the control program, the image forming apparatus, the step of detecting a value correlated with the amount of wear of the surface of each of the image carrier, According to the value correlated with the amount of wear of the surface of each image carrier, the peripheral speed difference between each image carrier and the transfer body is smaller than a first predetermined value. Individually controlling the peripheral speed of the image carrier. In the step of individually controlling the peripheral speed of each said image bearing member, you increase the degree of increasing the peripheral speed as said image bearing member is provided on the downstream side of the transfer member.

In one aspect, the pace at which the photoreceptor wears can be slower than before.
The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention that is understood in connection with the accompanying drawings.

FIG. 1 is a diagram showing an example of a device configuration of an image forming apparatus according to an embodiment. FIG. 4 is a diagram illustrating a state where a toner image is transferred from a photoconductor to an intermediate transfer belt. FIG. 3 is an enlarged view of a contact portion between a photoconductor and an intermediate transfer belt. FIG. 4 is a diagram illustrating an example in which white streaks are generated in an image due to wear of a photoconductor. FIG. 1 is a diagram showing an example of a configuration of an image forming apparatus according to an embodiment. 5 is a flowchart illustrating a part of a process executed by the image forming apparatus according to the embodiment. It is a figure which shows the content of peripheral speed information. FIG. 3 is a block diagram showing an example of a hardware configuration of the image forming apparatus according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed description thereof will not be repeated. In addition, each embodiment and each modification described below may be appropriately and selectively combined.

[Internal Structure of Image Forming Apparatus 100]
Referring to FIG. 1, image forming apparatus 100 according to the embodiment will be described. FIG. 1 is a diagram illustrating an example of an apparatus configuration of the image forming apparatus 100.

  FIG. 1 shows an image forming apparatus 100 as a color printer. Hereinafter, the image forming apparatus 100 as a color printer will be described, but the image forming apparatus 100 is not limited to a color printer. For example, image forming apparatus 100 may be a monochrome printer, a facsimile, or a multi-function peripheral (MFP: Multi-Functional Peripheral) of a monochrome printer, a color printer, and a facsimile.

  The image forming apparatus 100 includes an image forming unit 1Y, 1M, 1C, 1K, an intermediate transfer belt 30 (transfer member), a primary transfer roller 31, a secondary transfer roller 33 (transfer section), a cassette 37, and a fixing device. The apparatus includes a device 40, a cleaning unit 53, and a control device 101.

  The image forming apparatus 100 includes a toner bottle 15Y for supplying yellow (Y) toner, a toner bottle 15M for supplying magenta (M) toner, a toner bottle 15C for supplying cyan (C) toner, and a black toner bottle 15C. (BK) and a toner bottle 15B that supplies the toner. The image forming unit 1Y receives the supply of toner from the toner bottle 15Y and forms a yellow (Y) toner image. The image forming unit 1M receives a supply of toner from the toner bottle 15M and forms a magenta (M) toner image. The image forming unit 1C receives a supply of toner from the toner bottle 15C and forms a cyan (C) toner image. The image forming unit 1K receives a supply of toner from the toner bottle 15K and forms a black (BK) toner image. The image forming units 1Y, 1M, 1C, and 1K are sequentially arranged along the rotation direction of the intermediate transfer belt 30.

  Each of the image forming units 1Y, 1M, 1C, and 1K includes a photoconductor 10, a charging roller 11, an exposing unit 12, a developing unit 13, and a cleaning unit 17.

  The photoconductor 10 is an image carrier that carries a toner image. As an example, a photosensitive drum having a photosensitive layer formed on its surface is used as the photosensitive member 10.

  The charging roller 11 uniformly charges the surface of the photoconductor 10. The exposure unit 12 irradiates the photoconductor 10 with a laser in response to a control signal from the control device 101, and exposes the surface of the photoconductor 10 according to a designated image pattern. As a result, an electrostatic latent image corresponding to the input image is formed on the photoconductor 10.

  The developing device 13 develops the electrostatic latent image using a developer including a toner, a carrier, and an external additive. The developer is supplied from a toner bottle. The developing device 13 includes a developing roller 14. The developing device 13 applies a developing bias to the developing roller 14 to cause the toner to adhere to the surface of the developing roller 14. The developing device 13 rotates the developing roller 14 to transfer toner from the developing roller 14 to the photoconductor 10. Thereby, a toner image corresponding to the electrostatic latent image is developed on the surface of the photoconductor 10.

  The photoconductor 10 and the intermediate transfer belt 30 are in contact with each other at a portion where the primary transfer roller 31 is provided. A predetermined transfer bias is applied to the contact portion, and the toner image developed on the photoconductor 10 is transferred to the intermediate transfer belt 30 by the transfer bias. At this time, the yellow (Y) toner image, the magenta (M) toner image, the cyan (C), and the black (BK) toner images are sequentially superimposed and transferred to the intermediate transfer belt 30. As a result, a color toner image is formed on the intermediate transfer belt 30.

  The cleaning unit 17 includes a cleaning blade. The cleaning blade is pressed against the photoconductor 10 and collects toner remaining on the surface of the photoconductor 10 after the transfer to the intermediate transfer belt 30.

  The cassette 37 is provided, for example, below the image forming apparatus 100. Paper S (transfer medium) is set in the cassette 37. The sheets S are sent one by one from the cassette 37 to the secondary transfer roller 33. The secondary transfer roller 33 transfers the toner image transferred to the intermediate transfer belt 30 to the sheet S. By synchronizing the timing of feeding and transporting the sheet S with the position of the toner image on the intermediate transfer belt 30, the toner image is transferred to an appropriate position on the sheet S. Thereafter, the sheet S is sent to the fixing device 40.

  The fixing device 40 includes a heating roller 41 and a pressure roller 42 pressed against the heating roller 41. The fixing device 40 melts the toner image on the sheet S passing between the heating roller 41 and the pressure roller 42 by heating the heating roller 41, and fixes the toner image on the sheet S. Thereafter, the sheet S is discharged to the tray 48.

  The cleaning unit 53 includes a cleaning blade. The cleaning blade is pressed against the intermediate transfer belt 30 and collects the toner remaining on the intermediate transfer belt 30 after the transfer of the toner image. The toner is transported by a transport screw (not shown) and collected in a waste toner container (not shown).

  The control device 101 controls, for example, a motor 105 (see FIG. 5) for controlling the rotation of the photoconductor 10, a motor 106 (see FIG. 5) for controlling the rotation of the primary transfer roller 31, and the like. The motors 105 and 106 are driven by, for example, PWM (Pulse Width Modulation) control.

[Overview of Image Forming Apparatus 100]
The outline of the rotation control of the photoconductor 10 and the intermediate transfer belt 30 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a state in which a toner image is transferred from the photoconductor 10 to the intermediate transfer belt 30.

  In FIG. 2, a space is provided between the photoconductor 10 and the intermediate transfer belt 30 for convenience of description, but the photoconductor 10 and the intermediate transfer belt 30 are actually in contact with each other. The photoconductor 10 and the intermediate transfer belt 30 rotate while contacting each other in the direction of the arrow shown in FIG.

  As shown in FIG. 2, first, a yellow (Y) toner image 51Y is transferred from the photoreceptor 10Y to the intermediate transfer belt 30. Next, the magenta (M) toner image 51M is transferred from the photoconductor 10M to the intermediate transfer belt 30. Next, the cyan (C) toner image 51C is transferred from the photoconductor 10C to the intermediate transfer belt 30. Next, a black (BK) toner image 51K is transferred from the photoconductor 10K to the intermediate transfer belt 30. Thereafter, the toner images 51Y, 51M, 51C, and 51K transferred to the intermediate transfer belt 30 are transferred to the sheet S at a contact portion between the intermediate transfer belt 30 and the secondary transfer roller 33. Hereinafter, the photoconductors 10Y, 10M, 10C, and 10K are also collectively referred to as the photoconductor 10.

  FIG. 3 is an enlarged view of a contact portion between the photoconductor 10 and the intermediate transfer belt 30. As shown in FIG. 3, a toner 51 and an external additive 52 exist between the photoconductor 10 and the intermediate transfer belt 30. The external additive 52 is for improving the chargeability, fluidity, and durability of the toner 51. The external additive 52 is made of, for example, silicon (Si) or titanium (Ti).

  As shown in the example (A) of FIG. 3, in the initial stage, the photoconductor 10 and the intermediate transfer belt 30 are rotating at the same peripheral speed. However, as the photoreceptor 10 continues to be used, its surface is worn. Therefore, the diameter of the photoconductor 10 becomes shorter, and the peripheral speed of the photoconductor 10 becomes slower than the peripheral speed of the intermediate transfer belt 30, as shown in an example (B) of FIG. As a result, a peripheral speed difference occurs between the photoconductor 10 and the intermediate transfer belt 30, and the photoconductor 10 is damaged in the rotation direction by the external additive 52.

  As the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 increases, the pace at which the surface of the photoconductor 10 is worn increases. This is particularly noticeable when the photosensitive layer formed on the surface of the photoconductor 10 is formed of a thick film. For example, when the thickness of the photosensitive layer is 27.5 μm, 3 to 4 μm is worn by the use of the photoconductor 10. When the thickness of the photosensitive layer is 38.5 μm, 20 to 23 μm is worn by use of the photoconductor 10. As the thickness of the photosensitive layer increases, the amount of wear of the photosensitive layer increases. When an AC (Alternating Current) roller charging method is used as the charging method for the photoconductor 10, the amount of wear particularly increases.

  Various phenomena occur when the photosensitive layer of the photoconductor 10 is worn. One example of the phenomenon is an increase in the wear pace of the photoconductor 10. As the photoconductor 10 wears, the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 increases, and the pace at which the photoconductor 10 wears further increases.

  Another example of the phenomenon caused by the wear of the photoconductor 10 is shown in FIG. FIG. 4 is a diagram illustrating an example in which white streaks are generated in the image 71 due to wear of the photoconductor 10.

  When the photoreceptor 10 is damaged by the external additive 52, the surface thereof becomes uneven. FIG. 4 shows irregularities 70 on the surface of the photoconductor 10K. In the example of FIG. 4, irregularities of about 4 μm occur between the convex portions and the concave portions on the surface of the photoconductor 10K. Due to the unevenness 70, white streaks 72A to 72C are generated in the generated image 71. The white stripes 72 </ b> A to 72 </ b> C are formed at the convex portions of the unevenness 70.

  The cause of the white streaks 72A to 72C will be described. As shown in FIG. 2, when a toner image (for example, a toner image 51 </ b> C) provided on the upstream side of the photoconductor 10 </ b> K passes through the photoconductor 10 </ b> K, the transfer between the photoconductor 10 </ b> K and the intermediate transfer belt 30 is performed. Pressure is applied at the nip. At that time, the pressure increases in the convex portion of the photoconductor 10K, and decreases in the concave portion of the photoconductor 10K. That is, the toner image is condensed on the convex portion of the photoconductor 10K. Therefore, the transferability to the sheet S is reduced at the convex portion of the photoconductor 10K. As a result, the density of the toner image in the convex portion of the photoconductor 10K is lower than that in the other portions, and white stripes 72A to 72C appear in the image 71.

  In order to suppress the above-described event caused by the wear of photoconductor 10, image forming apparatus 100 according to the present embodiment detects a value representing the amount of wear of photoconductor 10, and determines the value of photoconductor 10 in accordance with the detected value. The peripheral speed of at least one of the photoconductor 10 and the intermediate transfer belt 30 is controlled so that the peripheral speed difference between the intermediate transfer belt 30 and the intermediate speed belt is smaller than the current peripheral speed difference. Since the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 is reduced, the image forming apparatus 100 can delay the pace at which the photoconductor 10 is worn. Further, the image forming apparatus 100 can suppress white stripes caused by unevenness of the surface of the photoconductor 10.

  Note that the value representing the wear amount of the photoconductor 10 is not limited to the wear amount itself of the photoconductor 10, but is a numerical value correlated with the wear amount of the photoconductor 10 (for example, the number of rotations of the photoconductor 10 up to the present). There may be. In the following, for convenience of description, a value representing the amount of wear of the photoconductor 10 is also simply referred to as “amount of wear”.

[Relationship between configurations]
With reference to FIG. 5, a configuration for controlling the peripheral speed of the photoconductor 10 and the intermediate transfer belt 30 will be described. FIG. 5 is a diagram illustrating an example of the configuration of the image forming apparatus 100.

  As shown in FIG. 5, the image forming apparatus 100 includes a photoconductor 10, a primary transfer roller 31, a detection unit 90, and a control device 101.

  The detecting unit 90 detects the amount of wear of the photoconductor 10. Details of the method of detecting the wear amount will be described later. The detection unit 90 outputs the detected amount of wear to the control device 101.

  The control device 101 controls at least one of the photoconductor 10 and the intermediate transfer belt 30 so that the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 becomes smaller than a predetermined value according to the wear amount of the photoconductor 10. Control. As an example, the control device 101 controls the peripheral speed of the photoconductor 10 by performing PWM control on the motor 105 for driving the photoconductor 10, and performs PWM control on the motor 106 for driving the intermediate transfer belt 30. Controls the peripheral speed of the intermediate transfer belt 30. The details of the control method of the photoconductor 10 and the intermediate transfer belt 30 will be described later.

  The control device 101 may be configured to control only the rotation of the photoconductor 10, may be configured to control only the rotation of the intermediate transfer belt 30, or may be configured to control the rotation of the intermediate transfer belt 30. It may be configured to control both of the belts 30.

[Method of detecting wear amount]
Hereinafter, a method of detecting the wear amount of the photoconductor 10 by the detection unit 90 (see FIG. 3) will be described. Various methods can be adopted as a method for detecting the wear amount of the photoconductor 10. Hereinafter, detection methods 1 to 4 which are examples of a method of detecting the wear amount of the photoconductor 10 by the detection unit 90 will be described in order.

(Abrasion detection method 1)
As described in FIG. 1, the photoconductor 10 is uniformly charged by the charging roller 11. The magnitude of the current flowing through the charging roller 11 changes depending on the degree of contact between the photoconductor 10 and the charging roller 11. Focusing on this point, the image forming apparatus 100 detects the value of the current flowing through the charging roller 11 and estimates the wear amount of the photoconductor 10 according to the current value. As an example, the current value is detected by a current detection sensor (not shown).

  The correlation between the value of the current flowing through the charging roller 11 and the wear amount of the photoconductor 10 is obtained in advance by, for example, an experiment. The correlation may be held as a table in which the amount of wear of the photoconductor 10 is associated with each current value, or a function of using the current value flowing through the charging roller 11 as an explanatory variable and the amount of wear of the photoconductor 10 as an objective variable. May be retained.

  In another aspect, the image forming apparatus 100 detects a current value flowing through the primary transfer roller 31 (see FIG. 1), and estimates a wear amount of the photoconductor 10 according to the current value. The magnitude of the current flowing through the primary transfer roller 31 changes depending on the degree of contact with the photoconductor 10.

  The correlation between the current value flowing through the primary transfer roller 31 and the wear amount of the photoconductor 10 is obtained in advance by, for example, an experiment. The correlation may be held as a table in which the wear amount of the photoconductor 10 is associated with each current value, or the current value flowing through the primary transfer roller 31 is used as an explanatory variable, and the wear amount of the photoconductor 10 is used as a target variable. It may be stored as a function.

  Note that the image forming apparatus 100 does not detect the wear amount of the photoconductor 10 from the magnitude of the current flowing through the primary transfer roller 31, but instead detects the amount of current flowing between the primary transfer roller 31 and the photoconductor 10. The wear amount of the photoconductor 10 may be detected.

(Abrasion detection method 2)
Next, a method 2 for detecting the wear amount of the photoconductor 10 will be described.

  When the photoreceptor 10 is worn, the diameter of the photoreceptor 10 becomes shorter and the peripheral speed of the photoreceptor 10 becomes slower. Therefore, the interval between the toner images on the intermediate transfer belt 30 changes according to the abrasion amount of the photoreceptor 10. Focusing on this point, the image forming apparatus 100 estimates the wear amount of the photoconductor 10 according to the interval between the toner images on the intermediate transfer belt 30.

  More specifically, the image forming apparatus 100 is provided with an optical sensor (not shown) for photographing the intermediate transfer belt 30. The image forming apparatus 100 transfers a toner image having a predetermined shape (for example, a patch image or a line image) to the intermediate transfer belt 30 at a constant time interval. The toner images transferred at regular time intervals are captured by an optical sensor. The optical sensor is arranged to include at least two toner images in its field of view. The image forming apparatus 100 detects an interval between each toner image from the obtained image. The interval between the toner images becomes longer as the photoconductor 10 wears. Focusing on this point, the image forming apparatus 100 calculates the change amount of the current toner image interval based on the toner image interval of the photoconductor 10 in the initial state. The image forming apparatus 100 determines that the wear of the photoconductor 10 is more advanced as the amount of change becomes larger.

(Wear amount detection method 3)
Next, a method 3 for detecting the wear amount of the photoconductor 10 will be described.

  The photoconductor 10 wears as it is used. In view of this, the image forming apparatus 100 estimates the wear amount of the photoconductor 10 from the usage amount of the photoconductor 10.

  In one aspect, image forming apparatus 100 estimates the wear amount of photoconductor 10 according to the number of rotations (rotation history) from the start of rotation of photoconductor 10 to the present. The amount of wear increases as the number of rotations of the photoconductor 10 increases, and decreases as the number of rotations of the photoconductor 10 decreases.

  In another aspect, the image forming apparatus 100 estimates the wear amount of the photoconductor 10 according to the sliding distance of the photoconductor 10 with respect to the intermediate transfer belt 30. The wear amount of the photoconductor 10 increases as the sliding distance increases, and decreases as the sliding distance decreases.

  In still another aspect, image forming apparatus 100 estimates the wear amount of photoconductor 10 according to the number of prints of image forming apparatus 100 up to the present. The number of prints is counted up, for example, every time printing is performed. The wear amount of the photoconductor 10 increases as the number of prints increases, and decreases as the number of prints decreases.

(Abrasion detection method 4)
Next, a method 4 for detecting the wear amount of the photoconductor 10 will be described.

  The wear amount of the photoconductor 10 may be detected by a distance sensor (not shown). The distance sensor is provided around the photoconductor 10 and detects a distance between the distance sensor and the photoconductor 10. The image forming apparatus 100 calculates the wear amount of the photoconductor 10 according to the distance obtained from the distance sensor. The wear amount of the photoconductor 10 increases as the distance obtained from the distance sensor increases, and decreases as the distance decreases.

[Circuit speed control method]
As described above, the control device 101 (see FIG. 5) controls the photosensitive drum 10 so that the peripheral speed difference between the photosensitive drum 10 and the intermediate transfer belt 30 becomes smaller than a predetermined value in accordance with the wear amount of the photosensitive drum 10. The peripheral speed of at least one of the body 10 and the intermediate transfer belt 30 is controlled. Various methods can be employed for controlling the peripheral speed of the photoconductor 10 and the intermediate transfer belt 30. Hereinafter, control methods 1 to 4, which are examples of a method of controlling the peripheral speed of the photoconductor 10 and the intermediate transfer belt 30, will be sequentially described.

(Control method 1)
If the wear amount of the photoconductor 10 increases, the peripheral speed of the photoconductor 10 decreases. Therefore, the control device 101 increases the peripheral speed of the photoconductor 10 as compared with the current peripheral speed as the wear amount of the photoconductor 10 increases. Thereby, the control device 101 can make the peripheral speed of the photoconductor 10 approach the peripheral speed of the intermediate transfer belt 30.

  Preferably, control device 101 increases only the peripheral speed of photoconductor 10. That is, the control device 101 maintains the peripheral speed of the intermediate transfer belt 30. The controller 101 makes the peripheral speed of the photoconductor 10 faster than the current peripheral speed as the wear amount of the photoconductor 10 increases. By controlling only the peripheral speed of the photoconductor 10, the configuration and processing for changing the peripheral speed of the intermediate transfer belt 30 are omitted.

  When a plurality of photoconductors 10Y, 10M, 10C, and 10K (see FIG. 2) are provided in the image forming apparatus 100, the control device 101 determines the peripheral speeds of the photoconductors 10Y, 10M, 10C, and 10K individually. Control. Since the photoconductor provided on the downstream side of the intermediate transfer belt 30 wears faster, the controller 101 increases the peripheral speed of the photoconductor provided on the downstream side of the intermediate transfer belt 30 to a greater degree. . The downstream side refers to a side where the toner image is conveyed on the intermediate transfer belt 30.

  In the example of FIG. 2, the control device 101 sets the degree of increasing the peripheral speed of the photoconductor 10K larger than the degree of increasing the peripheral speed of the photoconductor 10C, and sets the degree of increasing the peripheral speed of the photoconductor 10C to the circumference of the photoconductor 10M. The peripheral speed of the photoconductor 10M is made larger than the peripheral speed of the photoconductor 10Y.

(Control method 2)
The control method 2 of the peripheral speed by the control device 101 will be described.

  In the control method 1, the control device 101 increases the peripheral speed of the photoconductor 10 as the wear amount of the photoconductor 10 increases. On the other hand, in the control method 2, the control device 101 makes the peripheral speed of the intermediate transfer belt 30 lower than the current peripheral speed as the wear amount of the photoconductor 10 increases. Thereby, the control device 101 can make the peripheral speed of the intermediate transfer belt 30 approach the peripheral speed of the photoconductor 10.

  Preferably, the peripheral speed of the intermediate transfer belt 30 is reduced while maintaining the peripheral speed of the photoconductor 10. By controlling only the peripheral speed of the intermediate transfer belt 30, the configuration and processing for changing the peripheral speed of the photoconductor 10 are omitted.

(Control method 3)
The control method 3 of the peripheral speed by the control device 101 will be described.

  In the above control methods 1 and 2, the control device 101 approaches the peripheral speed of one of the photoconductor 10 and the intermediate transfer belt 30 to the other peripheral speed. On the other hand, in the control method 3, the control device 101 adjusts the peripheral speed of one of the photoconductor 10 and the intermediate transfer belt 30 to the other. That is, the control device 101 sets the peripheral speed ratio between the photoconductor 10 and the intermediate transfer belt 30 to 1.0. Thereby, the peripheral speed of the photoconductor 10 and the peripheral speed of the intermediate transfer belt 30 become equal to each other.

  At this time, the control device 101 may control only the peripheral speed of the photoconductor 10 to make the peripheral speeds of the photoconductor 10 and the intermediate transfer belt 30 equal, or may control only the peripheral speed of the intermediate transfer belt 30. The peripheral speeds of the photoconductor 10 and the intermediate transfer belt 30 may be made equal, or the peripheral speeds of both the photoconductor 10 and the intermediate transfer belt 30 may be controlled to make the peripheral speeds of the photoconductor 10 and the intermediate transfer belt 30 equal. Is also good.

  Note that the control device 101 does not need to strictly make the peripheral speeds of the photoconductor 10 and the intermediate transfer belt 30 equal, and may have a certain difference. For example, the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 may be within a predetermined range (for example, within ± 3%).

(Control method 4)
The control method 4 of the peripheral speed by the control device 101 will be described.

  In the control method 3 described above, the example in which the control device 101 equalizes the peripheral speed of the photoconductor 10 and the peripheral speed of the intermediate transfer belt 30 has been described. On the other hand, in the control method 4, the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 becomes smaller than a first predetermined value equal to or less than the current peripheral speed difference, and the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 is changed. The control device 101 controls at least one of the photoconductor 10 and the intermediate transfer belt 30 so that the speed difference is equal to or greater than a second predetermined value smaller than the first predetermined value. That is, the control device 101 reduces the peripheral speed difference in a state where a certain peripheral speed difference is provided between the photoconductor 10 and the intermediate transfer belt 30. By providing a certain peripheral speed difference in this manner, the transferability from the photoconductor 10 to the intermediate transfer belt 30 is improved, and transfer failure is improved.

  As an example, the control device 101 stores the peripheral speed ratio (for example, 1.003) between the photoconductor 10 and the intermediate transfer belt 30 in the initial state, and sets the photoconductor 10 to the peripheral speed ratio in the initial state. Further, the peripheral speed of the intermediate transfer belt 30 is controlled.

[Timing to change peripheral speed]
Hereinafter, the timing at which the control device 101 changes the peripheral speed of the photoconductor 10 and the intermediate transfer belt 30 will be described.

  The control device 101 executes the peripheral speed changing process of any of the control methods 1 to 4 at a timing at which a predetermined peripheral speed changing condition is satisfied. Whether or not the peripheral speed changing condition is satisfied is determined, for example, based on the detected wear amount of the photoconductor 10.

  In one aspect, the wear amount of the photoconductor 10 is represented by the number of rotations of the photoconductor 10 up to the present. The peripheral speed change condition is satisfied when the rotation speed exceeds a predetermined rotation speed. For example, when the life of the photoconductor 10 in the initial state is 600 krot (= 600 × 1000 rotations), the control device 101 determines that the peripheral speed change condition is satisfied every 100 krots (= 100 × 1000 rotations). Then, a peripheral speed changing process is executed. As described above, the peripheral speed changing process is executed at the timing when the rotation speed of the photoconductor 10 reaches the predetermined rotation speed. Preferably, control device 101 increases the peripheral speed of the photoconductor by a constant peripheral speed difference (for example, 0.05 m / sec) every 100 krot.

  In another aspect, the wear amount of the photoconductor 10 is represented by the number of prints of the image forming apparatus 100 up to the present. The peripheral speed change condition is satisfied when the number of prints exceeds a predetermined number. For example, when the life of the photoconductor 10 expires when 120k sheets (= 120 × 1000 sheets) of A4 size paper are printed, the control device 101 changes the peripheral speed every time 20k sheets (20 × 1000 sheets) are printed. It is determined that the condition has been satisfied, and the peripheral speed changing process is executed.

  In still another aspect, the peripheral speed changing condition includes a predetermined timing in the early morning, a timing when the power of the image forming apparatus 100 is turned on, a timing when printing is started, a timing when printing is completed, and a timing when the print job is executed. Is satisfied at the timing. As described above, the peripheral speed changing process is executed at every predetermined timing.

  In yet another aspect, the peripheral speed change condition is satisfied when the temperature around the image forming apparatus 100 has changed by a predetermined value (for example, 5 ° C. to 10 ° C.) or more from the previous change of the peripheral speed. Alternatively, the peripheral speed change condition is satisfied when the humidity around the image forming apparatus 100 has changed by a predetermined value or more from the previous change of the peripheral speed.

  In still another aspect, the peripheral speed change condition is satisfied when a print image quality stabilizing function mounted in advance in image forming apparatus 100 is executed. The stabilizing function is executed, for example, every time 1000 prints are executed. The stabilizing function includes a color resist correcting function.

  In still another aspect, whether or not the peripheral speed change condition is satisfied is determined based on the wear amount of the photoconductor 10 detected by any of the detection methods 1 to 4. As an example, the peripheral speed change condition is satisfied when the wear amount of the photoconductor 10 becomes larger than a predetermined amount.

  In another aspect, the peripheral speed change condition is satisfied when the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 becomes larger than a predetermined value (for example, 0.1 mm / sec). The peripheral speed of the photoconductor 10 is calculated according to the amount of wear of the photoconductor 10. The peripheral speed of the intermediate transfer belt 30 is predetermined and constant. The image forming apparatus 100 calculates the peripheral speed difference by calculating the difference between the peripheral speed of the photoconductor 10 and the peripheral speed of the intermediate transfer belt 30.

[Control Structure of Image Forming Apparatus 100]
The control structure of the image forming apparatus 100 will be described with reference to FIGS. FIG. 6 is a flowchart illustrating a part of a process executed by image forming apparatus 100. 6 is realized by the control device 101 (see FIG. 5) of the image forming apparatus 100 executing a control program 122 (see FIG. 8) described later.

  In step S10, the control device 101 determines whether or not it is time to change the peripheral speed of the photoconductor 10. The method of determining the timing is as described above, and thus the description will not be repeated. If the control device 101 determines that it is time to change the peripheral speed of the photoconductor 10 (YES in step S10), the control device 101 switches the control to step S12. Otherwise (NO in step S10), control device 101 executes the process of step S10 again.

  In step S12, the control device 101 detects the wear amount of the photoconductor 10 as the above-described detection unit 90 (see FIG. 5). As an example, the control device 101 detects the wear amount of the photoconductor 10 by any one of the detection methods 1 to 4.

  In step S20, the control device 101 determines whether to change the peripheral speed of the photoconductor 10 or not. As an example, whether to change the peripheral speed of the photoconductor 10 is determined based on the peripheral speed information 124. FIG. 7 is a diagram illustrating the contents of the peripheral speed information 124.

  In the example of FIG. 7, the peripheral speed information 124 includes the rotational speed of the photoconductor 10 up to the present, the diameter of the photoconductor 10, the circumference of the photoconductor 10, and the motor 105 before the peripheral speed is changed (see FIG. 5). , The peripheral speed of the photoconductor 10, the peripheral speed of the intermediate transfer belt 30, the peripheral speed difference ΔV between the photoconductor 10 and the intermediate transfer belt 30 before the peripheral speed is changed, and the peripheral speed difference ΔV are set to zero. For this purpose, the number of rotations of the motor 105 of the photoconductor 10 necessary for this is associated with each other.

  The control device 101 acquires the rotational speed up to the present time from history information (not shown) or the like, and acquires the peripheral speed difference ΔV associated with the rotational speed from the peripheral speed information 124. The control device 101 determines that the peripheral speed of the photoconductor 10 is changed when the acquired peripheral speed difference ΔV is equal to or larger than a predetermined value. When determining that the peripheral speed of photoconductor 10 is to be changed (YES in step S20), control device 101 switches the control to step S22. Otherwise (NO in step S20), control device 101 returns the control to step S10.

  In step S22, the control device 101 changes the peripheral speed of at least one of the photoconductor 10 and the intermediate transfer belt 30 by any one of the control methods 1 to 4. For example, it is assumed that the above-described control method 1 is employed as a method of controlling the peripheral speed. In this case, the rotation speed of the motor 105 of the photoconductor 10 necessary for setting the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 to zero is defined in advance in the peripheral speed information 124. The control device 101 acquires the rotation speed of the motor 105 corresponding to the rotation speed of the photoconductor 10 up to the present time from the peripheral speed information 124. The control device 101 drives the motor 105 at the acquired rotation speed. As a result, the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 becomes zero.

  The diameter, circumference, and the like of the photoconductor 10 do not necessarily need to be specified in the peripheral speed information 124. Preferably, in the peripheral speed information 124, a control value of the photoconductor 10 for reducing the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 is specified for each wear amount of the photoconductor 10. The wear amount of the photoconductor 10 includes “the number of rotations of the photoconductor 10 until now” in the peripheral speed information 124 in FIG. The control value of the photoconductor 10 includes “the number of rotations of the motor 105 of the photoconductor 10 necessary for reducing the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 to zero” in the peripheral speed information 124 in FIG. The control device 101 acquires a control value corresponding to the amount of wear detected in step S12 from the peripheral speed information 124, and controls the peripheral speed of the photoconductor 10 based on the control value.

[Hardware Configuration of Image Forming Apparatus 100]
An example of a hardware configuration of the image forming apparatus 100 will be described with reference to FIG. FIG. 8 is a block diagram illustrating an example of a hardware configuration of the image forming apparatus 100.

  As shown in FIG. 8, the image forming apparatus 100 includes a control device 101, a read only memory (ROM) 102, a random access memory (RAM) 103, a network interface 104, and a motor 105 for driving the photoconductor 10. And a motor 106 for driving the intermediate transfer belt 30, an operation panel 107, and a storage device 120.

  The control device 101 is composed of, for example, at least one integrated circuit. The integrated circuit includes, for example, at least one CPU (Central Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

  Control device 101 controls the operation of image forming apparatus 100 by executing various programs such as control program 122 according to the present embodiment. The control device 101 reads the control program 122 from the storage device 120 to the ROM 102 based on the reception of the execution instruction of the control program 122. The RAM 103 functions as a working memory, and temporarily stores various data necessary for executing the control program 122.

  An antenna (not shown) and the like are connected to the network interface 104. The image forming apparatus 100 exchanges data with an external communication device via the antenna. The external communication device includes, for example, a mobile communication terminal such as a smartphone, a server, and the like. Image forming apparatus 100 may be configured to be able to download control program 122 according to the present embodiment from a server via an antenna.

  The operation panel 107 includes a display unit and a touch panel. The display unit and the touch panel are overlapped with each other, and the operation panel 107 receives a touch operation on the display unit. Operation panel 107 receives, for example, a printing operation, a scanning operation, and the like for image forming apparatus 100.

  The storage device 120 is, for example, a storage medium such as a hard disk or an external storage device. Storage device 120 stores control program 122, peripheral speed information 124, and the like according to the present embodiment. The storage location of the peripheral speed information 124 is not limited to the storage device 120, and the peripheral speed information 124 is stored in a storage area (for example, a cache) of the control device 101, the ROM 102, the RAM 103, an external device (for example, a server), or the like. May be.

  Control program 122 according to the present embodiment may be provided as a part of an arbitrary program, not as a single program. In this case, the process according to the present embodiment is realized in cooperation with an arbitrary program. Even a program that does not include such some modules does not depart from the gist of the control program 122 according to the present embodiment. Further, some or all of the functions provided by the control program 122 may be realized by dedicated hardware. Further, the image forming apparatus 100 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 122.

[Brief Summary]
As described above, the image forming apparatus 100 reduces the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 when the photoconductor 10 is worn. Preferably, image forming apparatus 100 reduces the peripheral speed difference with intermediate transfer belt 30 by increasing the peripheral speed of photoconductor 10. The image forming apparatus 100 can reduce the peripheral speed difference between the photoconductor 10 and the intermediate transfer belt 30 to reduce the wear rate of the photoconductor 10.

  The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1C, 1K, 1M, 1Y Image forming unit, 10, 10C, 10K, 10M, 10Y Photoconductor, 11 charging roller, 12 exposure unit, 13 developing device, 14 developing roller, 15B, 15C, 15K, 15M, 15Y Toner bottle , 17, 53 cleaning unit, 30 intermediate transfer belt, 31 primary transfer roller, 33 secondary transfer roller, 37 cassette, 40 fixing device, 41 heating roller, 42 pressure roller, 48 tray, 51 toner, 51C, 51K, 51M , 51Y toner image, 52 external additives, 70 irregularities, 71 images, 72A, 72C white stripes, 90 detector, 100 image forming apparatus, 101 controller, 102 ROM, 103 RAM, 104 network interface, 105, 106 motor, 107 operation panel, 120 storage device 122 control program, 124 laps speed information.

Claims (9)

A plurality of image carriers on which an electrostatic latent image is formed on the surface according to the input image,
A plurality of developing devices for developing the electrostatic latent image as a toner image on the surfaces of the plurality of image carriers, respectively.
A transfer member that rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred;
A transfer unit for transferring the toner image transferred to the transfer body to a transfer medium,
A detection unit for detecting a value correlated with the amount of wear of the surface of each of the image carriers,
Depending on the value correlated with the amount of wear of the surface of each image carrier, the peripheral speed difference between each image carrier and the transfer member is smaller than the current peripheral speed difference. A control unit for individually controlling the peripheral speed of the image carrier,
Wherein the control unit, you increase the degree of increasing the image bearing member as the peripheral speed is provided on the downstream side of the transfer member, the image forming apparatus. The control unit maintains the peripheral speed of the transfer member, and increases the peripheral speed of each image carrier faster than the current peripheral speed as the value correlated with the amount of wear of the surface of each image carrier increases. to that, the image forming apparatus according to claim 1.   The control unit is configured such that a peripheral speed difference between each of the image carriers and the transfer body is smaller than a first predetermined value equal to or less than the current peripheral speed difference, and smaller than the first predetermined value. The image forming apparatus according to claim 1, wherein the peripheral speed of each of the image carriers is individually controlled so as to be equal to or greater than a second predetermined value larger than 0. 4. The control unit acquires, from the peripheral speed information, a control value corresponding to the amount of wear of the surface of each of the image carriers detected by the detection unit, and obtains each of the images based on the control value. The peripheral speed of the carrier is individually controlled, and the peripheral speed information is a control value relating to the peripheral speed of each of the image carriers to make the peripheral speed difference smaller than the current value. defines for each value correlated with the amount of wear, the image forming apparatus according to any one of claims 1-3. The rotation control of each of the image carrier by the control unit is performed for each predetermined timing, an image forming apparatus according to any one of claims 1-4. The value correlated with the wear amount of the surface of each image carrier is the number of rotations from the start of rotation of the image carrier to the present,
The image forming apparatus according to claim 5 , wherein the predetermined timing includes a timing at which the rotation speed reaches a predetermined rotation speed. Rotation control of each of the image carrier by the control unit, the predetermined condition indicating that each of said image bearing member is worn is executed when filled, to any one of claims 1-4 The image forming apparatus as described in the above. A method for controlling an image forming apparatus, comprising:
The image forming apparatus includes:
A plurality of image carriers on which an electrostatic latent image is formed on the surface according to the input image,
A plurality of developing devices for developing the electrostatic latent image as a toner image on the surfaces of the plurality of image carriers, respectively.
A transfer member that rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred;
A transfer unit for transferring the toner image transferred to the transfer body to a transfer medium,
The control method includes:
Detecting a value correlated with the amount of wear on the surface of each of the image carriers;
According to the value correlated with the amount of wear of the surface of each image carrier, the peripheral speed difference between each image carrier and the transfer body is smaller than a first predetermined value, so that each said Individually controlling the peripheral speed of the image carrier,
In the step of individually controlling the peripheral speed of each of said image bearing member, it increases the degree of increasing the image bearing member as the peripheral speed is provided on the downstream side of the transfer member, the control method. A control program for an image forming apparatus,
The image forming apparatus includes:
A plurality of image carriers on which an electrostatic latent image is formed on the surface according to the input image,
A plurality of developing devices for developing the electrostatic latent image as a toner image on the surfaces of the plurality of image carriers, respectively.
A transfer member that rotates while being in contact with the plurality of image carriers, and onto which the toner images respectively developed on the plurality of image carriers are transferred;
A transfer unit for transferring the toner image transferred to the transfer body to a transfer medium,
The control program includes:
Detecting a value correlated with the amount of wear on the surface of each of the image carriers;
In accordance with a value correlated with the amount of wear of the surface of each image carrier, the peripheral speed difference between each image carrier and the transfer body is smaller than a first predetermined value, Controlling the peripheral speed of the image carrier individually, and
In the step of individually controlling the peripheral speed of each of said image bearing member, it increases the degree of increasing the image bearing member as the peripheral speed is provided on the downstream side of the transfer member, the control program.

Images