JP6657997B2 - Image forming apparatus and method for controlling amount of lubricant on image carrier - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet based on a print job, and a method for controlling a lubricant amount on an image carrier.

  2. Description of the Related Art An image forming apparatus that forms an image on a sheet by an electrophotographic method is known. In the electrophotographic method, a toner image is formed on an outer peripheral surface (hereinafter, referred to as a “front surface”) of a photoconductor using static electricity, and the toner image is transferred to a sheet or an intermediate transfer body. The surface of the photoconductor is worn according to the number of prints, that is, the photoconductor travel distance (number of rotations). Abrasion on the surface of the photoreceptor causes not only the sliding of the cleaning member (for example, a cleaning blade) used for toner collection and the photoreceptor but also the complicated friction phenomenon due to the influence of intervening particles such as toner and external additives such as a lubricant. Accompany.

  FIG. 1 is a graph showing the relationship between the amount of wear on the surface of the photoconductor and the travel distance of the photoconductor. The horizontal axis represents the travel distance of the photoconductor, and the vertical axis represents the amount of wear on the surface of the photoconductor. As shown in FIG. 1, as the traveling distance of the photoconductor increases, the shaving property (wear rate) of the photoconductor decreases non-linearly as compared with the initial stage of travel (initial operation). At the beginning of traveling, the photoreceptor has a high shaving property (high wear rate), and the shaving property of the photoreceptor decreases according to the traveling distance of the photoreceptor. It shows the behavior that the shaving property is reduced. The main factor of such behavior is a decrease in the pressing force due to wear of the cleaning blade (hereinafter sometimes referred to as “CL blade”).

  The mainstream of the electrophotographic cleaning process is blade cleaning. This is a system in which the residual toner (transfer residual toner) on the photoconductor is scraped off by sliding the edge of a rubber blade called a cleaning blade into contact with the surface of the photoconductor and sliding. In the initial stage of the travel of the photoconductor, the pressure (pressing force) of the cleaning blade against the photoconductor is highest.

  FIG. 2 is a graph showing the relationship between the amount of lubricant collected by a cleaning blade (denoted as “CL blade” in the figure) and the distance traveled by the photoconductor. The horizontal axis represents the distance traveled by the photoconductor, and the vertical axis represents the amount recovered by the cleaning blade. Represents The lubricant is added for the purpose of reducing the frictional resistance acting between the photoreceptor and the cleaning blade, and eliminating problems such as friction between the photoreceptor and the cleaning blade. As shown in FIG. 2, there is a relationship between the photoreceptor abrasion (wear rate) and the lubricant retrievability (lubricant recovery amount) by the cleaning blade, and when the photoreceptor is easily abraded, the lubricant is removed together with the photoreceptor. Are also easily collected. Therefore, when the shaving property of the photoconductor changes as shown in FIG. 1, the lubricant collecting ability of the cleaning blade changes as shown in FIG. In this case, if the lubricant supply amount is constant, the lubricant amount on the photoconductor varies depending on the travel distance of the photoconductor as shown in FIG.

  FIG. 3 is a graph showing the relationship between the amount of lubricant on the photoreceptor and the travel distance of the photoreceptor. The horizontal axis represents the travel distance of the photoreceptor, and the vertical axis represents the amount of lubricant on the photoreceptor. As shown in FIG. 3, since the amount of lubricant collected by the cleaning blade is large in the initial stage of travel, the amount of lubricant on the photoconductor is small as a result, and the amount of lubricant collected by the cleaning blade decreases as the travel distance of the photoconductor increases. As a result, the amount of lubricant on the photoreceptor increases.

  Even if the amount of lubricant on the photoreceptor is set to an appropriate value at the beginning of traveling, if the amount of lubricant on the photoreceptor fluctuates due to the lapse of time from the beginning of traveling of the photoreceptor, specifically, When the amount of the lubricant increases, the wear rate of the cleaning blade increases due to the increase in the amount of the photoconductor lubricant, and the life of the cleaning blade is shortened. This is because the amount of lubricant on the photoreceptor increases, the releasability of the photoreceptor surface increases, and the amount of toner external additive that slips between the photoreceptor surface and the cleaning blade decreases, and the contact area between the cleaning blade and the photoreceptor surface decreases. This is considered to be caused by an increase in the cleaning blade wear rate. Also, when the amount of the lubricant on the photoconductor changes, the surface potential of the photoconductor changes. As a result, there is a problem that the amount of toner to be developed fluctuates and the image density fluctuates.

  Japanese Patent Application Laid-Open No. H11-163,873 aims to suppress the reduction in cleaning performance of small particle size toner due to abrasion of the cleaning blade in accordance with the progress of the degree of wear of the cleaning blade based on the number of images formed or the travel distance of the image carrier. An image forming apparatus that increases the amount of a lubricant applied to an image carrier is disclosed.

  Patent Literature 2 discloses that the first part has two parts, a first part having a high density and a second part having a low density. As the depth from the surface in contact with the brush roller increases, the first part decreases, and There is disclosed an image forming apparatus including a lubricant applying device provided with a lubricant molded product that is compression-molded so that the second portion is increased, and a brush roller. The lubricant molded product described in Patent Literature 2 has a case in which a decrease in pressure for pressing the lubricant molded particles against the brush roller due to aging or a decrease in the scraping force of the lubricant molded product of the brush roller due to wear of the brush roller occurs. Even in this case, the lubricant molded product has a two-layer structure for the purpose of not reducing the amount of the lubricant applied to the image carrier.

JP-A-2003-330320 JP 2012-63493 A

  Patent Literatures 1 and 2 do not mention the relationship between the shaving property (wear rate) of the photoconductor and the amount of lubricant on the photoconductor. In other words, those disclosed in Patent Literatures 1 and 2 do not have a concept of controlling the amount of lubricant on the photoreceptor in consideration of the variation in the abrasion (wear rate) of the photoreceptor.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to secure the stability of the amount of lubricant on an image carrier on which development is performed even when the shaving property (wear rate) of a photoconductor varies. And

  An image forming apparatus according to one embodiment of the present invention includes a rotatable first image carrier that carries a toner image, a charging unit that charges the first image carrier, and irradiates light to the first image carrier. An exposure section for writing an electrostatic latent image by the exposure section, a developing section for developing a toner image from the electrostatic latent image written on the first image carrier by the exposure section, and a developing section for developing the toner image from the first image carrier. And a transfer unit for performing electrostatic transfer to the second image carrier. The image forming apparatus may further include a cleaning member that contacts the first image carrier and collects a transfer residual toner that is a toner remaining on the first image carrier after transferring the toner image to the transfer unit. A wear amount measuring unit for measuring the wear amount of the surface of the image carrier. Further, the image forming apparatus is configured to perform the non-linearly fluctuating scraping of the first image carrier based on the wear amount of the first image carrier measured by the wear amount measuring unit. A control unit is provided for controlling the amount of lubricant on the first image carrier.

According to the present invention, the amount of the lubricant on the first image carrier is controlled in accordance with the sharpness of the first image carrier based on the measurement result. Therefore, the stability of the amount of the lubricant on the first image carrier can be ensured.
Problems, configurations, and effects other than those described above will be apparent from the following description of the embodiments.

5 is a graph showing a relationship between a wear amount of a photoconductor and a travel distance of the photoconductor. 6 is a graph showing a relationship between a lubricant collection amount of a cleaning blade and a photoconductor traveling distance. 5 is a graph showing the relationship between the amount of lubricant on the photoreceptor and the travel distance of the photoreceptor. FIG. 2 is a diagram illustrating an example of a main part of the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a control system of the image forming apparatus according to the first embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a main part of an image forming apparatus according to a second embodiment of the present invention. FIG. 9 is a block diagram illustrating an example of a control system of an image forming apparatus according to a second embodiment of the present disclosure. 6 is a graph showing a relationship between a converted value of a lubricant amount on a photoconductor and a toner supply amount to a cleaning blade. 6 is a graph showing a relationship between a converted value of a lubricant amount on a photoreceptor and a toner charge amount. 6 is a flowchart illustrating processing of an image forming method according to the first and second embodiments of the present invention. 6 is a table showing evaluation results of experiments performed by the image forming apparatuses according to the first and second embodiments of the present invention. 9 is an example of a control parameter table showing a correspondence relationship between a photoconductor wear speed and a cleaning auxiliary brush θ. 7 is an example of a control parameter table showing a correspondence relationship between a photoconductor wear speed and a recovery roller pushing amount. 9 is an example of a control parameter table showing a correspondence relationship between a photoconductor wear speed and a collection roller θ. 5 is an example of a control parameter table showing a correspondence relationship between a photosensitive member wear rate and an AC component applied to a charge amount adjusting device. FIG. 5 is a diagram illustrating an evaluation device for controlling a lubricant amount in a transfer unit. 5 is a graph showing the relationship between the amount of lubricant on the photoreceptor and the transfer voltage. 5 is an example of a control parameter table showing a correspondence relationship between a photosensitive member wear rate and a transfer voltage. FIG. 4 is an explanatory diagram illustrating a relationship between potentials in development. 9 is an example of a control parameter table showing a correspondence relationship between a photosensitive member wear rate and a charging potential. 9 is an example of a control parameter table showing a correspondence relationship between a photosensitive member wear rate and a coating brush θ.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the following description and the drawings, the same elements or elements having the same functions are denoted by the same reference numerals, and overlapping description will be omitted.

<1. First Embodiment>
[Outline of Configuration of Image Forming Apparatus]
FIG. 4 is a diagram illustrating an example of a main part of the image forming apparatus according to the first embodiment of the present invention.
The image forming apparatus 1 shown in FIG. 4 includes a photoconductor 10, a charging device 20, an exposure device 30, a developing device 40, a transfer device 50, a charge amount adjusting device 60, and a cleaning auxiliary device 75. The image forming apparatus 1 is an example of a “lubricant toner external addition system” using toner particles obtained by adding an external additive including a lubricant to colored particles.

  The photoconductor 10 (an example of a first image carrier) is a drum that is driven to rotate in the direction a (clockwise in the figure) and carries an electrostatic latent image. The photoconductor 10 has an organic photoconductor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal base. Examples of the resin constituting the photosensitive layer include polycarbonate resin, silicone resin, polystyrene resin, acrylic resin, methacrylic resin, epoxy resin, polyurethane resin, vinyl chloride resin, and melamine resin.

  The charging device 20 (an example of a charging unit) uniformly charges the surface (outer peripheral surface) of the photoconductor 10. For example, a charging device (charging grid voltage applying unit) is used as the charging device 20, and the photoconductor 10 is charged to a constant potential via a charging grid or the like (not shown).

  The exposure device 30 (an example of an exposure unit) exposes the surface of the photoconductor 10 charged by the charging device 20 to form an electrostatic latent image. A laser or the like is used as a light source of the exposure device 30.

  The developing device 40 (an example of a developing unit) visualizes (develops) the electrostatic latent image formed on the surface of the photoconductor 10 by the exposure device 30 using a developer containing toner. The developing device 40 includes a developing sleeve 41 arranged so as to face the photoconductor 10 via a development area of the photoconductor 10. For example, a DC voltage having the same polarity as the charging polarity of the charging device 20 or a DC voltage having the same polarity as the charging polarity of the charging device 20 is superimposed on the AC voltage by a developing voltage applying unit (not shown). A development bias is applied. As a result, reversal development for attaching toner to the electrostatic latent image formed by the exposure device 30 is performed. The toner image formed on the photoconductor 10 by the developing device 40 is conveyed to a transfer area (transfer nip portion) formed between the transfer device 50 and the toner image. In FIG. 4, the developing sleeve 41 rotates in the direction a and performs counter rotation with respect to the photoconductor 10, but the rotating direction is not limited to this example.

  The transfer device 50 (an example of a transfer unit) forms a transfer region (transfer nip portion) with the photoconductor 10. The transfer device 50 transfers the toner image formed on the photoconductor 10 to the intermediate transfer body 51 (an example of a second image carrier) in a transfer area. The intermediate transfer body 51 is, for example, an endless belt. In the transfer area, a voltage having a polarity opposite to the toner charging polarity is normally applied to the transfer device 50 by a transfer voltage application unit (not shown), and the toner image on the photoconductor 10 conveyed to the transfer area is transferred onto the intermediate transfer body 51. Is transferred to

  The charge amount adjustment device 60 (an example of a charge amount adjustment unit) adjusts the charge amount of the transfer residual toner that is the toner remaining on the photoconductor 10 without being transferred onto the intermediate transfer member 51 at the transfer nip portion of the transfer device 50. I do. When the transfer residual toner on the photoconductor 10 passes near the charge amount adjusting device 60, the charge is adjusted by being charged or removed.

  The charge amount adjusting device 60 includes a corotron charger using corona discharge, a scorotron charger, a static elimination needle, a static elimination cloth using a nonwoven fabric, or an electrode or roller provided with a minute gap and opposed to the photoconductor 10. Alternatively, any material such as a contact-type roller that can adjust the charge amount of the toner before and after the passage may be used. The voltage applied to the toner may be any one of a DC voltage (DC voltage), an AC voltage (AC voltage), and a DC voltage with an AC voltage superimposed thereon. Further, since the charge amount adjusting device 60 is a unit for adjusting the charge amount of the toner reaching the cleaning blade 70, the charge amount adjusting device 60 may be disposed at any position as long as it is disposed between the developing device 40 and the cleaning blade 70. Good.

  The cleaning blade 70 (an example of a cleaning member) and the cleaning auxiliary device 75 scrape and remove (transfer) the transfer residual toner remaining on the photoconductor 10 after the transfer. The cleaning auxiliary device 75 is disposed upstream of the cleaning blade 70 in the photoconductor rotation direction (between the transfer device 50 and the cleaning blade 70). As the cleaning auxiliary brush 76, for example, a brush roller (conductive fur brush) in which conductive fibers are provided as bristle members on the outer peripheral surface of a rotating roller is used. The toner whose charge amount has been adjusted by the charge amount adjusting device 60 is conveyed to the cleaning auxiliary device 75, and a part of the toner is collected by the cleaning auxiliary brush 76 abutting on the photoconductor 10. The toner collected by the cleaning auxiliary brush 76 is further collected by a collection roller 77 which is in contact with the cleaning auxiliary brush 76. After that, the remaining toner on the photoconductor 10 is transported to the cleaning blade 70 and collected by the cleaning blade 70.

  The toner image transferred to the intermediate transfer body 51 is transferred to a recording material (for example, paper) at a secondary transfer position (not shown), and then is conveyed to a fixing device (not shown) to be fixed on the recording material. You.

  On the other hand, the photoreceptor 10 whose surface toner has been collected by the cleaning blade 70 is charged again by the charging device 20, the next electrostatic latent image is formed by the exposure device 30, and the toner image is formed by the developing device 40. repeat.

  For example, a flat cleaning blade made of an elastic material such as rubber is used as the cleaning blade 70. Generally, a blade cleaning method in which an edge portion of the cleaning blade is brought into contact with the surface of the photoconductor 10 is used as a cleaning method.

  As physical properties of the cleaning blade, rebound resilience and hardness are important. The rebound resilience is preferably from 10 to 80% at a temperature of 25 ° C, more preferably from 30 to 70%. The JIS-A hardness is preferably from 20 to 90 degrees, and particularly preferably from 60 to 80 degrees. When the JIS-A hardness is less than 20 degrees, the cleaning blade is too soft, and the blade is easily turned. On the other hand, when the JIS-A hardness is greater than 90 degrees, it is difficult to follow slight irregularities and foreign matters on the photoconductor 10, and "slip-through" of toner particles is likely to occur.

  The contact load of the cleaning blade 70 on the photoconductor 10 is preferably 0.1 to 40.0 N / m, and more preferably 1 to 25 N / m. If the contact load is smaller than 0.1 N / m, the cleaning power is insufficient, and the image is easily stained. On the other hand, when the contact load is larger than 40 N / m, the abrasion of the photoreceptor 10 becomes large, and the image is easily blurred. The contact load can be measured by pressing the leading edge (edge portion) of the cleaning blade 70 against the balance, or by arranging a sensor such as a load cell at the contact position of the leading edge of the cleaning blade 70 with respect to the photoconductor 10. For example, a method of electrically measuring the temperature is used.

[About behavior of lubricant]
Here, the behavior of the lubricant will be described.
In the case of the image forming apparatus 1 of the lubricant toner external addition type shown in FIG. 4, the lubricant is supplied to the image portion together with the toner on the photoreceptor 10 in the developing process, and the lubricant released from the toner alone is supplied to the non-image portion. To the photoreceptor 10. Thereafter, the image forming process shifts to a transfer process. In the transfer process, a part of the lubricant moves to the intermediate transfer body 51 together with the toner, and another part of the lubricant stays on the photoreceptor 10 together with the untransferred toner or with the lubricant alone. Then, the toner reaches the cleaning auxiliary brush 76 and is collected by the cleaning auxiliary brush 76 together with some toner.

  After that, the residual toner not collected by the cleaning auxiliary brush 76 reaches the cleaning blade 70. A part of the lubricant adhering to the toner is scraped off by the cleaning blade 70 together with the residual toner, and another part of the lubricant is separated from the residual toner and the edge of the cleaning blade 70 together with the lubricant originally existing alone. While staying in the portion, it passes through between the photoconductor 10 and the cleaning blade 70 and is fixed on the photoconductor 10. The lubricant adhering to the toner staying at the edge of the cleaning blade 70 continues to be sequentially removed.

  Further, the lubricant originally fixed on the photoreceptor 10 is also scraped off by the toner staying at the edge of the cleaning blade 70 or the toner carried to the cleaning blade 70 acting as an abrasive. .

  Regarding the cleaning auxiliary brush 76, since the pressing force (pressure in contact with the photoconductor 10) is low and the contact area is rough due to the brush, the cleaning blade 70 originally scrapes the lubricant fixed on the photoconductor 10. Very little compared to.

[Control system of image forming apparatus]
FIG. 5 is a block diagram illustrating an example of a control system of the image forming apparatus 1.
FIG. 5 illustrates elements considered necessary for the description of the present invention or related elements, and the control system of the image forming apparatus 1 is not limited to this example.

  The image forming apparatus 1 includes a control device 100 (an example of a control unit) that performs a series of controls for feeding a sheet, forming an image on the sheet, and discharging the sheet, and a storage device 101. The control device 100 includes an arithmetic processing device including a CPU (Central Processing Unit) (not shown) and a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ROM stores a program executed by the CPU of the control device 100, data used when the program is executed, and the like. An MPU (Micro-Processing Unit) may be used instead of the CPU.

  The control device 100 includes a photoconductor 10, a charging device 20, an exposure device 30, a developing device 40, a transfer device 50, a charge amount adjusting device 60, a cleaning auxiliary device 75, a wear amount measuring unit 80, It is connected to the storage device 101 and the communication I / F 102 so that data communication is possible. The control device 100 controls the operation of the entire image forming apparatus 1, that is, the operation of each unit in the image forming apparatus 1.

  The storage device 101 is an example of a storage unit, and stores parameters used when the CPU of the control device 100 controls the image forming apparatus 1, data obtained by executing a program, and the like. For example, the storage device 101 stores information such as control parameters (for example, control parameter tables 31 to 37 described later) for controlling the amount of the lubricant present on the photoconductor 10 according to the sharpness of the photoconductor 10. You. The control parameters may be stored in the ROM. Further, the storage device 101 may store a program executed by the CPU of the control device 100.

  The communication I / F 102 is an interface for transmitting and receiving data to and from a personal computer (PC) 120 as an operation terminal via a network or a dedicated line. As the communication I / F 102, for example, an NIC (Network Interface Card) is used.

  The wear amount measuring unit 80 measures a direct or indirect parameter (wear amount parameter) representing the amount of wear on the surface of the photoconductor 10, and transmits the measurement result to the control device 100. There are three methods for measuring the wear amount parameter, which will be described in detail later.

  The control device 100 receives a job via an operation display unit or a network (not shown), and performs control according to the job. The control device 100 outputs a display signal to the operation display unit, and the operation display unit displays an operation screen for displaying various setting screens for inputting various operation instructions and setting information, various processing results, and the like (not shown). Display on the display panel.

  The control device 100 directly detects or predicts a change in the abrasion of the photoconductor 10 and controls the lubricity recovery (lubricant recovery amount) of the cleaning blade 70 or the lubricity supply (lubricant supply amount) to the photoconductor 10. The lubricant collecting ability of the cleaning blade 70 is controlled by adjusting the amount of toner supplied to the cleaning blade 70 or the amount of charged toner. The lubricant supply property to the photoreceptor 10 is controlled by adjusting a transfer voltage or a charging potential in a lubricant toner external addition system. In the lubricant application system described later, the lubricant is controlled by the rotation speed of an application brush for applying the lubricant to the photoreceptor 10.

<2. Second Embodiment>
The present invention is not limited to an image forming apparatus using a lubricant toner externally added system, but is also effective in a lubricant application system for applying a lubricant to a photoreceptor.

[Outline of Configuration of Image Forming Apparatus]
FIG. 6 is a diagram illustrating an example of a main part of an image forming apparatus according to a second embodiment of the present invention.
The image forming apparatus 1A shown in FIG. 6 includes a lubricant applying device 90 downstream of the cleaning blade 70 in the rotation direction of the photoconductor. The lubricant application device 90 includes an application brush 91 in contact with the photoreceptor 10, a solidified lubricant (hereinafter, referred to as “solid lubricant”) 92 pressed against the application brush 91 by an elastic member such as a spring (not shown). And a fixing blade 93 in contact with the photoconductor 10. As the solid lubricant 92, for example, zinc stearate is used.

  The lubricant scraped from the solid lubricant 92 by the application brush 91 in a granular form is applied to the surface of the photoconductor 10 and is fixed on the photoconductor 10 by the fixing blade 93. Thereafter, the lubricant fixed on the photoreceptor 10 is scraped off by the toner staying at the edge of the cleaning blade 70 or the toner conveyed to the cleaning blade 70 acting as an abrasive.

[Control system of image forming apparatus]
FIG. 7 is a block diagram illustrating an example of a control system of the image forming apparatus 1A.
In the control system of the image forming apparatus 1 </ b> A shown in FIG. 7, a lubricant application device 90 is connected to the control device 100 so that data communication is possible. Although the cleaning auxiliary device 75 (see FIG. 4) is omitted in FIG. 7, the cleaning auxiliary device 75 may be arranged in the image forming apparatus 1A.

  The control device 100 controls the rotation operation and the like of the application brush 91 of the lubricant application device 90 according to the program.

[Effect of cleaning blade on amount of lubricant on photoconductor]
The effect of the cleaning blade on the amount of lubricant on the photoreceptor was tested using a lubricant application type image forming apparatus 1A shown in FIG.
The amount of toner (0.1 to 0.6 g / m ² ) that reaches the cleaning blade 70 is changed from the state in which the lubricant is applied to the photoconductor 10 by the lubricant application device 90, and the photoconductor 10 is rotated 30 times. The amount of the lubricant on the photoreceptor 10 after the measurement was measured. The amount of toner supplied to the cleaning blade 70 was adjusted by changing the transfer bias condition. As for the amount of the lubricant, after the lubricant after the application of the lubricant passes through the vicinity of the cleaning blade 70, the surface layer of the photoreceptor 10 is cut out and substituted by the ratio of zinc in zinc stearate determined by FT-IR (Fourier transform infrared spectrophotometer). did.

FIG. 8 is a graph showing the relationship between the amount of the lubricant on the photoconductor 10 and the amount of toner supplied to the cleaning blade 70. The horizontal axis indicates the amount of toner supplied to the cleaning blade 70, and the vertical axis indicates the amount of toner supplied to the cleaning blade 70. In terms of lubricant amount.
From FIG. 8, it can be confirmed that the lubricant collection amount varies depending on the toner amount supplied to the cleaning blade 70, and that the lubricant collection amount increases as the toner amount supplied to the cleaning blade 70 increases.

  Next, with respect to a state in which the lubricant is applied on the photoconductor 10, the toner charge amount (+5 to -31 [mu] C / g) of the toner reaching the cleaning blade 70 is changed, and the photoconductor after the photoconductor is rotated 30 times is changed. The amount of lubricant on body 10 was measured. The amount of the lubricant was determined by FT-IR (Fourier transform infrared spectrophotometer) as in the case of FIG.

FIG. 9 is a graph showing the relationship between the amount of lubricant on the photoreceptor 10 and the amount of toner charged to the cleaning blade 70. The abscissa indicates the amount of toner charged to the cleaning blade 70, and the ordinate indicates the amount of toner charged. The upper lubricant value is shown.
From FIG. 9, it can be confirmed that the lubricant collection amount varies depending on the toner charge amount supplied to the cleaning blade 70, and the lubricant collection amount increases as the toner charge amount (negative polarity in this example) supplied to the cleaning blade 70 increases.

[Operation of Image Forming Apparatus]
FIG. 10 is a flowchart illustrating a process of an image forming method in the image forming apparatus 1 (1A) according to the first and second embodiments of the present invention.
The CPU included in the control device 100 realizes the processing illustrated in FIG. 10 by executing a program recorded in the ROM or the storage device 101. When the control device 100 detects that a job has been input, it starts the processing of this flowchart.

  First, the control device 100 controls the wear amount measuring unit 80 to directly or indirectly measure a parameter indicating directly or indirectly the amount of wear on the surface of the photoconductor 10 (S1).

  Next, the control device 100 calculates the wear speed of the photoconductor 10 from the travel distance (the number of rotations) of the photoconductor 10 and the measured value of the wear amount parameter (S2).

  Next, the control device 100 reads a control parameter from the control parameter table of the corresponding control target in the image forming apparatus 1 (1A) based on the wear speed of the photoconductor 10 (S3).

  Next, the control device 100 controls the lubricant collecting property of the cleaning blade 70 or the lubricant supplying property to the photoconductor 10 based on the read control parameters (S4). The control device 100 periodically executes the processing of steps S1 to S4 according to the traveling distance of the photoconductor 10. For example, the above-described series of processing is performed at the time of creating a patch image (inter-image patch) between images or at the time of normal image formation.

<3. Experimental example>
Experiments of Experimental Examples 1 to 7 described below were performed using the image forming apparatus 1 (FIG. 4). According to the configuration of the image forming apparatus 1, the photoconductor 10, the developing device 40, the transfer device 50, the toner, the cleaning blade 70, the cleaning auxiliary device 75, and the like were set as follows.

[Experiment conditions]
Photoreceptor 10 The photoreceptor 10 is a drum-shaped organic photoreceptor in which a 25 μm-thick photosensitive layer made of a polycarbonate resin is formed on the outer peripheral surface of a drum-shaped metal base made of aluminum, for example, having a width of about 350 mm. Was used. The rotation speed of the photoconductor 10 during the measurement was 400 mm / sec.

-About the developing device 40 As the developing device 40, the one provided with the developing sleeve 41 rotated and driven at a linear velocity of 600 mm / min was used. A bias voltage having the same polarity as the surface potential of the photoconductor 10 is applied to the developing sleeve 41, and reversal development is performed by a two-component developer.

Regarding Transfer Device 50 An endless belt made of a polyimide resin having conductivity was used as the intermediate transfer member 51. The transfer device 50 is in pressure contact with the photoconductor 10 via the intermediate transfer body 51. As the transfer device 50, a transfer roller to which a voltage having a polarity opposite to the charging polarity of the toner is normally applied is used.

-Charge control device 60 A corotron charger was used, and the applied voltage was obtained by superimposing an AC voltage on a DC voltage.

Regarding the cleaning blade 70 The cleaning blade 70 is made of urethane rubber having a rebound resilience of 50% (25 ° C.), a JIS-A hardness of 70 °, a thickness of 2.00 mm, a free length of 10 mm, and a width of 324 mm. Was used. The cleaning blade 70 is configured to be able to press and separate from the surface of the photoconductor 10. The contact force of the cleaning blade 70 against the photoreceptor 10 during the pressure contact was set to 20 N / m and the contact angle to 15 °.

Regarding the cleaning auxiliary brush 76 The cleaning auxiliary brush 76 is made of conductive polyester and has a fineness of 10 d, a density of 45 KF / inch ² , a hair length of 3 mm, an outer diameter of 13.4 mm and a width of 348 mm. Using. The cleaning auxiliary brush 76 has a pressing amount of 1 mm into the photoreceptor 10 and has a with rotation (b direction) relatively moving with respect to the rotation direction (a direction) of the photoreceptor 10. As the collection roller 77 that comes into contact with the cleaning auxiliary brush 76, a collection roller made of stainless steel and having an outer diameter of 10 mm and a width of 351 mm was used. The amount of the recovery roller 77 pushed into the cleaning auxiliary brush 76 was set to 1 mm, and counter rotation (b direction) was performed to oppose the rotation direction (b direction) of the cleaning auxiliary brush 76. In order to scrape the collected toner, a stainless metal blade having a thickness of 0.05 mm is brought into counter contact with the collection roller 77 (so-called leading method).

Regarding Toner The toner constituting the two-component developer is composed of toner particles having a volume average particle diameter of 6.5 μm manufactured by an emulsion polymerization method and has negative chargeability. A toner obtained by adding 0.2 parts by weight of zinc stearate to toner particles 1 as a lubricating external additive (lubricating agent) to the toner particles was used. The toner particles used in the experiment are negatively charged, and the lubricant is positively charged.

In the above, the surface potential Vo of the photoconductor 10 in the non-exposed area is set to −750 [V], the surface potential Vi of the photoconductor 10 in the exposed area is set to −100 [V], and the frequency of 6000 [Hz] is applied to the developing sleeve 41. A developing bias having an amplitude of 800 [V] and a DC component of Vdc-550 [V] was applied. The primary transfer voltage (transfer device 50) was set to +700 [V], and the transfer efficiency was set to 90% or more. In this case, the amount of toner remaining after transfer on the photoconductor 10 is 0.5 g / m ² .

  Using the image forming apparatus 1 described above, the toner in the developing device 40 was refilled in advance for each experiment, and experiments and evaluations were performed in a state where the amount of the lubricant in the initial stage of the movement of the photoconductor 10 was uniformed.

  FIG. 11 is a table showing evaluation results of experiments performed using the image forming apparatus 1. In FIG. 11, the evaluation results are shown for each of the traveling distance (number of rotations) of the photoconductor 10 for the comparative example and the experimental examples 1 and 4 to 7, and the traveling distance of the photoconductor is represented by the number of rotations [krot]. Experimental Examples 2 and 3 were omitted because they had the same results as Experimental Example 1. One [krot] is 1000 rotations. The evaluation results are indicated by “○” for good and “x” for poor.

[Comparative example]
The comparative example is an example in which none of the controls of Experimental Examples 1 to 7 is performed. In the comparative example, no problem occurs with respect to the wear of the cleaning blade 70 and the difference in density variation from the initial image (the image at the initial stage of photoconductor travel) in the halftone (intermediate gradation) up to 200 krot in the photoconductor travel distance. However, at 300 krot, both qualities had problems. Note that in FIG. 11, the difference in density variation from the initial image in the halftone is described as “Δ image density from the beginning”.

[Experimental example 1]
As described above, the sharpness of the photoconductor 10 decreases non-linearly according to the travel distance of the photoconductor, and the amount of lubricant collected by the cleaning blade 70 varies depending on the sharpness of the photoconductor 10 (photoconductor 10). If the scraping property of the powder decreases, the recoverability of the lubricant also decreases.) Therefore, when the amount of the lubricant supplied is constant, the behavior in which the amount of the lubricant on the photoconductor 10 increases non-linearly is shown (FIG. 3).

  Therefore, in Experimental Example 1, the amount of the lubricant collected by the cleaning blade 70 was controlled according to the shaving property of the photoconductor 10. The direction of the control is a direction in which the amount of the collected lubricant is increased in accordance with a decrease in the shaving property of the photoconductor 10. Regarding the shaving property of the photoreceptor 10, a reflection spectroscopic interferometer is used for the wear amount measuring unit 80, and the amount of wear on the surface of the photoreceptor 10 is measured by the reflection spectroscopic interferometer. The wear rate was determined. In Experimental Example 1, the wear rate was determined every 20 krot.

  FIG. 12 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the cleaning auxiliary brush θ. Is the ratio of the rotation speed of the cleaning auxiliary brush 76 to the rotation speed of the photoconductor 10.

  As shown in FIG. 6, the amount of lubricant collected by the cleaning blade 70 can be controlled by the amount of toner supplied to the cleaning blade 70. Therefore, in Experimental Example 1, the amount of toner supplied to the cleaning blade 70 was controlled by adjusting the rotation speed of the cleaning auxiliary brush 76. When the rotation speed of the cleaning auxiliary brush 76 is reduced, the amount of toner collected by the cleaning auxiliary brush 76 decreases. As a result, the amount of toner supplied to the cleaning blade 70 increases, and the amount of lubricant collected by the cleaning blade 70 increases. In Experimental Example 1, the rotation speed of the cleaning auxiliary brush 76 was set by θ, which is a ratio to the rotation speed of the photoconductor 10. The cleaning auxiliary brush θ was controlled in accordance with the wear rate of the photoconductor 10 as shown in FIG.

As shown in the control parameter table 31 of FIG. 12, the setting is made so that θ of the cleaning auxiliary brush 76 with respect to the photoconductor 10 decreases as the shaving property of the photoconductor 10 decreases.
In FIG. 12, when the photoconductor wear speed per 20,000 rotations (20 krots) of the photoconductor 10 is less than 0.05 μm, the cleaning auxiliary brush θ is 0.3.
When the wear rate of the photoconductor is 0.05 or more and less than 0.1 [μm / 20 krot], the cleaning auxiliary brush θ is 0.6.
When the photosensitive member wear rate is 0.1 or more and less than 0.15 [μm / 20 krot], the cleaning auxiliary brush θ is 1.
When the photosensitive member wear rate is 0.15 or more and less than 0.2 [μm / 20 krot], the cleaning auxiliary brush θ is 1.5.
Further, when the photosensitive member wear rate is 0.2 or more [μm / 20 krot], the cleaning auxiliary brush θ is 2.

  In the experimental example 1, as in the comparative example, no problem occurred in both the quality of the cleaning blade abrasion and the difference in density variation from the initial image in the halftone up to the photoconductor travel distance of 200 krot. Furthermore, in Experimental Example 1, no problem occurred in both qualities even at a photoconductor traveling distance of 300 krot.

  As described above, Experimental Example 1 has a configuration in which θ of the cleaning auxiliary brush 76 with respect to the photoconductor 10 is reduced in accordance with a decrease in the shaving property of the photoconductor 10 based on the measurement result of the wear amount of the photoconductor 10. As a result, the amount of toner supplied to the cleaning blade 70 increases, and the amount of lubricant collected by the cleaning blade 70 is stabilized, and the stability of the amount of lubricant on the photoconductor can be ensured. Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the life of the cleaning blade 70 and to suppress the fluctuation of the image density.

  In Experimental Example 1, the θ control of the cleaning auxiliary brush 76 (the lubricant collection by the cleaning blade 70) is performed not only at the time of creating a patch image (inter-image patch) between images but also at the time of normal image formation. Volume control).

  In recent years, a photoconductor having a high hardness overcoat layer is sometimes used for the purpose of extending the life of the photoconductor. Even in a photoreceptor having a high hardness overcoat layer, the abrasion fluctuation according to the traveling distance of the photoreceptor shows a non-linear behavior as shown in FIG. This is a technique that is applicable and effective for stabilizing the amount of lubricant on the photoreceptor.

(Detection method of photoreceptor abrasion)
Here, measurement of the shaving property of the photoconductor 10 will be described. As described above, the reflection spectroscopic interferometer is used for the wear amount measuring unit 80, but the measuring method may be selected from the following three methods. These measurement methods are applicable not only to Experimental Example 1 but also to Experimental Examples 2 to 7.

−Direct detection−
The wear amount measuring unit 80 directly measures the thickness of the surface of the photoconductor 10 from the downstream side of the cleaning blade 70 in the circumferential direction of the photoconductor 10 to the developing device 40. As a measuring method, a spectroscopic method or an eddy current method may be used.

−Indirect detection−
The fact that the surface potential after charging of the photoconductor 10 fluctuates due to wear of the photoconductor 10 is used. First, the wear amount measuring unit 80 measures the surface potential between the charging device 20 and the exposure device 30 in the circumferential direction of the photoconductor 10 for each predetermined traveling distance of the photoconductor 10. The amount of wear and the surface potential according to the traveling distance of the photoconductor 10 are obtained in advance by an experiment, and a corresponding table is created and stored in the storage device 101 or the like. The wear amount measuring unit 80 measures the surface potential of the photoconductor 10, calculates the wear amount of the photoconductor 10 from the measured value and the correspondence table, and calculates the wear amount per unit travel distance of the photoconductor 10, that is, the wear speed. Is calculated.

−Prediction detection−
The wear characteristics of the photoconductor 10 at an average coverage (also referred to as a printing rate) assumed in actual use are obtained in advance by experiments. Then, the photoconductor wear speed with respect to the photoconductor travel distance in the corresponding coverage is calculated, and based on the calculated wear parameter, a lubricant amount control parameter (for example, the cleaning auxiliary brush θ in Experimental Example 1) is stored in the control parameter table 31. It is good.

  More specifically, the wear characteristics of the photoreceptor 10 for each average coverage with respect to the photoconductor travel distance are determined in advance by experiments, and the photoreceptor wear speed for each average coverage is calculated. The lubricant amount control parameter (the cleaning auxiliary brush θ in Experimental Example 1) is stored in the control parameter table 31. Under the control of the control device 100, the wear amount measuring unit 80 calculates, as the average coverage, the average value of the cumulative coverage from the beginning of traveling of the photoconductor 10 to the present, and from the control parameter table corresponding to the calculated average coverage. Then, the lubricant amount control parameter is read based on the photoconductor travel distance.

  As described above, a plurality of control parameter tables may be created for each average coverage, or a plurality of records may be prepared for each average coverage in one control parameter table. Each record includes a field of “average coverage”, a field of “photoconductor travel distance”, and a field of “control parameters (eg, cleaning auxiliary brush θ)”.

(Relation between inflection point P of photoconductor wear characteristic and detection period of wear amount)
Since the wear speed is large in the initial stage of the photoreceptor and gradually decreases after the inflection point P (see FIG. 1), the detection period of the wear amount by the wear amount measuring unit 80 is set to be equal to the initial period of the travel of the photoreceptor. May be set finely, and the running distance after the inflection point P of the wear characteristic with respect to the running distance may be set roughly after running (or after a lapse of time). In the direct detection and the indirect detection, the inflection point P can be grasped by calculating the wear speed of the photoconductor 10 (amount of wear per unit running distance of the photoconductor) for each detection cycle. For prediction detection, information on the inflection point P is stored on the control parameter table 31.

[Experimental example 2]
FIG. 13 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the amount of pushing in the recovery roller.

  In Experimental Example 2, the amount of toner supplied to the cleaning blade 70 was controlled by adjusting the amount of pushing of the recovery roller 77 in contact with the cleaning auxiliary brush 76 with respect to the cleaning auxiliary brush 76. By reducing the pushing amount of the collecting roller 77 to the cleaning auxiliary brush 76, the pressing force of the collecting roller 77 to the cleaning auxiliary brush 76 is reduced, and the amount of toner collected from the cleaning auxiliary brush 76 to the collecting roller 77 is reduced. As a result, the amount of toner held by the cleaning auxiliary brush 76 increases, and the amount of toner collected by the cleaning auxiliary brush 76 decreases. As a result, the amount of toner supplied to the cleaning blade 70 increases, and the amount of lubricant collected by the cleaning blade 70 increases.

  The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. The pushing amount control of the collecting roller 77 can be performed by using, for example, an eccentric cam or the like disposed on the opposite side of the collecting roller 77 from the cleaning auxiliary brush 76. In Experimental Example 2, by performing the control of the amount of pushing of the collecting roller shown in FIG. 13, the same evaluation result as in the case of θ control of the cleaning auxiliary brush of Experimental Example 1 was obtained.

As shown in the control parameter table 32 of FIG. 13, the setting is made so that the pushing amount of the collection roller 77 into the cleaning auxiliary brush 76 decreases as the sharpness of the photoconductor 10 decreases.
In FIG. 13, when the wear speed of the photoconductor per 20,000 rotations (20 krot) of the photoconductor 10 is less than 0.05 μm, the pushing amount of the collecting roller is 0.5 [mm].
Further, when the photoreceptor wear rate is 0.05 or more and less than 0.1 [μm / 20 krot], the pushing amount of the collection roller 77 is 0.8 [mm].
Further, when the photoconductor wear speed is 0.1 or more and less than 0.15 [μm / 20 krot], the pushing amount of the collection roller 77 is 1.1 [mm].
When the photosensitive member wear rate is 0.15 or more and less than 0.2 [μm / 20 krot], the pushing amount of the collection roller 77 is 1.4 [mm].
When the photosensitive member wear rate is 0.2 or more [μm / 20 krot], the pushing amount of the collection roller 77 is 1.8 [mm].

  As described above, the experimental example 2 has a configuration in which the pushing amount of the collection roller 77 into the cleaning auxiliary brush 76 is reduced in accordance with the reduction in the shaving property of the photoconductor 10. As a result, similarly to Experimental Example 1, the amount of toner supplied to the cleaning blade 70 increases, the amount of lubricant collected by the cleaning blade 70 is stabilized, and the stability of the amount of lubricant on the photoconductor can be ensured. . Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the life of the cleaning blade 70 and to suppress the fluctuation of the image density.

  In Experimental Example 2, similarly to Experimental Example 1, the pushing amount control of the collecting roller 77 was performed not only at the time of creating the inter-image patch but also at the time of normal image formation.

[Experimental example 3]
FIG. 14 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the collection roller θ.

  In Experimental Example 3, the amount of toner supplied to the cleaning blade 70 was controlled by adjusting the rotation speed of the collection roller 77 abutting on the cleaning auxiliary brush 76. By reducing the rotation speed of the collection roller 77, the amount of toner collected by the collection roller 77 from the cleaning auxiliary brush 76 decreases. The reason for this is that the probability of contact of the cleaning auxiliary brush 76 with the hairy member is reduced by reducing the nip passage length at which the collection roller 77 contacts the cleaning auxiliary brush 76. As a result, the amount of toner held by the cleaning auxiliary brush 76 increases, and the amount of toner collected by the cleaning auxiliary brush 76 decreases. As a result, the amount of toner supplied to the cleaning blade 70 increases, and the amount of lubricant collected by the cleaning blade 70 increases.

  The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. In Experimental Example 3, the rotation speed of the collection roller 77 was set based on the ratio θ to the rotation speed of the cleaning auxiliary brush 76. In Experimental Example 2, by performing the θ control of the collection roller 77 shown in FIG. 14, an evaluation result equivalent to that in the case of the θ control of the cleaning auxiliary brush of Experimental Example 1 was obtained.

As shown in the control parameter table 33 of FIG. 14, the setting is made such that the θ of the collection roller 77 with respect to the cleaning auxiliary brush 76 decreases as the sharpness of the photoconductor 10 decreases.
In FIG. 14, when the photoconductor abrasion speed per 20,000 rotations (20 krot) of the photoconductor 10 is less than 0.05 μm, the collection roller θ is 0.1.
When the photoconductor wear rate is 0.05 or more and less than 0.1 [μm / 20 krot], the collection roller θ is 0.3.
When the photoconductor wear speed is 0.1 or more and less than 0.15 [μm / 20 krot], the collection roller θ is 0.6.
When the wear rate of the photoconductor is 0.15 or more and less than 0.2 [μm / 20 krot], the collection roller θ is 0.8.
When the photosensitive member wear rate is 0.2 or more [μm / 20 krot], the collection roller θ is 1.1.

  As described above, Experimental Example 3 has a configuration in which θ of the recovery roller 77 with respect to the cleaning auxiliary brush 76 is reduced in accordance with a reduction in the shaving property of the photoconductor 10. As a result, similarly to Experimental Example 1, the amount of toner supplied to the cleaning blade 70 increases, the amount of lubricant collected by the cleaning blade 70 is stabilized, and the stability of the amount of lubricant on the photoconductor can be ensured. . Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the life of the cleaning blade 70 and to suppress the fluctuation of the image density.

  In Experimental Example 3, similarly to Experimental Example 1, the θ control of the collecting roller 77 was performed not only at the time of creating an inter-image patch but also at the time of normal image formation.

[Experimental example 4]
FIG. 15 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the AC component applied to the charge amount adjusting device.

  As shown in FIG. 9, the amount of lubricant collected by the cleaning blade 70 can be controlled by the amount of toner charge that reaches the cleaning blade 70. Therefore, in Experimental Example 4, the charge amount of the toner reaching the cleaning blade 70 was controlled by the charge amount adjusting device 60. Increasing the amount of toner charge (for example, negative polarity) that reaches the cleaning blade 70 increases the amount of lubricant collected by the cleaning blade 70.

  The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. The voltage applied to the charge amount adjusting device 60 is such that the DC component is 2 [kV], the AC frequency is 11 [kHz], and the peak-to-peak value Vpp of the AC component is changed as shown in FIG. Controlled.

As shown in the control parameter table 34 of FIG. 15, the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is set to increase as the sharpness of the photoconductor 10 decreases.
In FIG. 13, when the photoconductor wear speed per 20,000 rotations (20 krot) of the photoconductor 10 is less than 0.05 μm, the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is 8 [kV].
When the photoconductor wear rate is 0.05 or more and less than 0.1 [μm / 20 krot], the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is 7 [kV].
When the photoconductor abrasion speed is 0.1 or more and less than 0.15 [μm / 20 krot], the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is 6 [kV].
When the photoconductor wear rate is 0.15 or more and less than 0.2 [μm / 20 krot], the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is 5 [kV].
When the photosensitive member wear rate is 0.2 or more [μm / 20 krot], the peak-to-peak value Vpp of the AC component of the charge amount adjusting device 60 is 3 [kV].

  In Experimental Example 4, as in Experimental Example 1, there was no problem with both the abrasion of the cleaning blade and the difference in density variation from the initial image in the halftone even at the photosensitive member travel distance of 300 krot.

  As described above, Experimental Example 4 has a configuration in which the applied voltage of the charge amount adjusting device 60 is increased in accordance with the reduction in the shaving property of the photoconductor 10. As a result, the amount of lubricant collected by the cleaning blade 70 is stabilized, and the stability of the amount of lubricant on the photoconductor can be ensured, as in Experimental Example 1. Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the life of the cleaning blade 70 and to suppress the fluctuation of the image density.

  Note that the voltage applied to the charge amount adjusting device 60 is not limited to a voltage obtained by superimposing an AC voltage on a DC voltage, and may be a DC voltage or an AC voltage as long as the voltage increases the toner charge reaching the cleaning blade 70. .

  In Experimental Example 4, similarly to Experimental Example 1, the applied voltage control of the charge amount adjusting device 60 was performed not only at the time of creating an inter-image patch but also at the time of normal image formation.

[Experimental example 5]
In Experimental Examples 1 to 4, the stability of the amount of lubricant on the photoconductor is ensured by controlling the amount of lubricant collected by the cleaning blade 70 in accordance with the abrasion (wear rate) of the photoconductor 10. On the other hand, the stability of the amount of lubricant on the photoconductor is controlled by controlling the amount of lubricant supplied to the photoconductor 10 with respect to the fluctuation of the amount of lubricant on the photoconductor (FIG. 3) due to the fluctuation of the abrasion of the photoconductor 10. It is also possible to secure In other words, the amount of lubricant collected by the cleaning blade 70 is reduced and the amount of lubricant on the photosensitive member is increased as the abrasion of the photosensitive member 10 is reduced. By reducing the amount, the amount of the lubricant on the photoreceptor is stabilized. FIG. 16 shows an evaluation device for evaluating the control of the amount of lubricant in the transfer area in the transfer area in the image forming apparatus 1 of the lubricant toner external addition system.

FIG. 16 is a diagram illustrating an evaluation device for controlling the amount of lubricant in the transfer device.
The photoconductor 10 is, for example, a cylindrical member made of aluminum having an outer diameter of 100 mm and a length of 100 mm. A photoconductive layer having a thickness of 25 μm made of a polycarbonate resin is provided on the surface thereof. ing. The developing roller 13 is, for example, a cylindrical member made of aluminum having an outer diameter of 30 mm, and holds a developer of 250 g / m ^{2 on} a circumferential surface thereof. The photoconductor 11 and the developing roller 13 face each other with a distance of 250 μm. An AC voltage having a frequency of 6000 Hz, an amplitude of 800 V, and an offset of -450 V is applied to the developing roller 13. In this state, the developing roller 13 is rotated in the direction a at 600 mm / sec, and then the photoconductor 11 is rotated once in the direction a at 400 mm / sec. Thus, a toner layer of 5 g / m ² is formed on the photoconductor 11.

  Next, the developing roller 13 is largely separated from the photoconductor 11, and the rubber roller 12 provided with a conductive rubber layer on the surface thereof is brought into contact with the photoconductor 11. Then, an arbitrary voltage is applied to the metal core of the rubber roller 12, and in this state, the photoconductor 11 is rotated once in the direction a at 400 mm / sec. Since the rubber roller 12 is in contact with the photoconductor 11, the rubber roller 12 rotates in the direction b following the photoconductor 11. After one rotation, the toner image on the photoconductor 11 has transferred onto the rubber roller 12. An experiment was conducted by changing the voltage applied to the rubber roller 12, and the weight of the toner remaining on the photoconductor 11 and the amount of the lubricant at that time were measured. The transfer efficiency was determined from the weight of the toner formed on the photoconductor 11 and the amount of the toner remaining on the photoconductor 11 after the transfer. The transfer efficiency was obtained from the following equation.

Transfer efficiency =
(1−weight of transfer residual toner on photoconductor 11 / weight of toner on photoconductor 11 after development) × 100 (%)

  The amount of the lubricant was substituted by the ratio of zinc in zinc stearate determined by an X-ray photoelectron spectrometer. FIG. 17 shows the results of the experiment.

  FIG. 17 is a graph showing the relationship between the amount of the lubricant on the photoconductor and the transfer voltage. The horizontal axis represents the transfer voltage [V], and the vertical axis represents the amount of the lubricant on the photoconductor 10 [at%] (percent of atomic composition). And transfer efficiency [%].

  In FIG. 17, a solid line 111 indicates data of the amount of lubricant on the photoconductor 11, and a broken line 112 indicates data of transfer efficiency. As is clear from FIG. 17, when the transfer voltage exceeds a certain value (for example, 700 V), the amount of the lubricant remaining on the photoconductor 11 increases. On the other hand, when the transfer voltage is too high (for example, 900 V or more), it can be seen that the transfer efficiency decreases. From this, the following can be said.

-When the transfer voltage is increased, the amount of the lubricant supplied on the photoreceptor can be increased.
-If the transfer voltage is too high, the transfer efficiency will decrease.

  Therefore, in Experimental Example 5, the amount of lubricant supplied was controlled using the relationship between the transfer voltage and the amount of lubricant on the photoreceptor. That is, the supply amount of the lubricant was controlled by adjusting the transfer voltage within a range in which the transfer efficiency was not deteriorated in accordance with the scraping property (wear rate) of the photoconductor.

FIG. 18 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the transfer voltage.
The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. Then, transfer voltage control was performed based on the control parameter table 35 shown in FIG.

As shown in FIG. 18, the transfer voltage is set so as to decrease in accordance with the decrease in the sharpness of the photoconductor 10.
In FIG. 18, when the photoconductor wear speed per 20,000 rotations (20 krots) of the photoconductor 10 is less than 0.05 μm, the transfer voltage is 500 [V].
When the photosensitive member wear rate is 0.05 or more and less than 0.1 [μm / 20 krot], the transfer voltage is 720 [V].
When the wear rate of the photoconductor is 0.1 or more and less than 0.15 [μm / 20 krot], the transfer voltage is 780 [V].
When the photosensitive member wear rate is 0.15 or more and less than 0.2 [μm / 20 krot], the transfer voltage is 840 [V].
When the photosensitive member wear rate is 0.2 or more [μm / 20 krot], the transfer voltage is 900 [V].

  In Experimental Example 5, as in Experimental Example 1, no problem occurred in both the quality of the cleaning blade wear and the difference in density variation from the initial image in the halftone even at the photoconductor travel distance of 300 krot.

  As described above, Experimental Example 5 has a configuration in which the transfer voltage of the transfer device 50 is reduced in accordance with the reduction in the shaving property of the photoconductor 10. Thereby, the amount of lubricant supplied to the photoconductor 10 can be controlled, and the stability of the amount of lubricant on the photoconductor can be ensured. Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the service life of the cleaning blade 70 and to suppress the fluctuation of the image density, as in Experimental Example 1.

  In Experimental Example 5, similarly to Experimental Example 1, the above-described transfer voltage control was performed in a range where transfer efficiency could be ensured not only at the time of creating an inter-image patch but also at the time of normal image formation. Not limited to For example, only the inter-image patches may be controlled, and the control range of the transfer voltage may be expanded to a range where the effect on the image quality can be ignored.

[Experimental example 6]
As another method of controlling the lubricant supply amount in the lubricant toner external addition system, there is charge potential control. FIG. 19 shows the relationship between the potentials in the development. The image part in FIG. 20 is an exposure area, and the background part is a non-exposure area. As shown in FIG. 20, the difference between the exposure region potential Vi and the developing bias Vdc becomes the image portion potential difference, and the difference between the charging potential ≒ the non-exposure region potential Vo and the developing bias Vdc becomes the background portion potential difference.

  Since the lubricant is supplied from the developing device 40 to the background portion of the photoconductor 10 due to the background portion potential difference, the amount of the lubricant supplied to the background portion of the photoconductor 10 can be controlled by adjusting the background portion potential difference. . Since the lubricant in Experimental Example 6 is positively charged, the supply amount of the lubricant can be increased by increasing the background potential difference. In Experimental Example 6, the control of the background portion potential difference was controlled by the non-exposure region potential Vo, that is, the charging potential. However, when the background portion potential difference is reduced, the fogging margin is reduced, and when the background portion potential difference is increased, concern about carrier adhesion increases, so control must be performed during that time.

FIG. 20 is an example of a control parameter table showing the correspondence between the photosensitive member wear rate and the charging potential.
The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. Then, the developing bias Vdc was fixed at -550 V, and the charging potential was controlled based on the control parameter table 36 shown in FIG.

  In Experimental Example 6, as in Experimental Example 1, no problem occurred in both the quality of the cleaning blade and the density fluctuation difference from the initial image in the halftone even at the photoconductor traveling distance of 300 krot.

  As described above, Experimental Example 6 has a configuration in which the charging potential of the charging device 20 is reduced in accordance with the reduction in the shaving property of the photoconductor 10. Thereby, the amount of lubricant supplied to the photoconductor 10 can be controlled, and the stability of the amount of lubricant on the photoconductor can be ensured. Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the service life of the cleaning blade 70 and to suppress the fluctuation of the image density, as in Experimental Example 1.

  In Experimental Example 6, similarly to Experimental Example 1, the above-described charging potential control was performed in a range where transfer efficiency could be ensured not only at the time of forming an inter-image patch but also at the time of normal image formation. Not limited to For example, only the inter-image patch may be controlled, and the control range of the charging potential may be expanded to a range where the influence on the image quality can be ignored.

[Experimental example 7]
As described above, as a form of the lubricant supply, in addition to the image forming apparatus 1 (FIG. 4) of the external additive system of the lubricant toner, a lubricant application system as shown in the image forming apparatus 1A (FIG. 6) including the lubricant application apparatus 90. There is. In Experimental Example 7, a method of controlling a lubricant supply amount using the lubricant application device 90 will be described.

As the application brush 91 of the lubricant application device 90, a conductive polyester having a fineness of 3d, a density of 150 KF / inch ² , a bristle length of 3 mm, an outer diameter of 13.4 mm, and a width of 348 mm was used. The pushing amount of the application brush 91 into the photoreceptor 10 was set to 0.8 mm, and counter rotation (rotation direction a) was performed with respect to the rotation direction a of the photoreceptor 10. As the solid lubricant 92, solidified zinc stearate was used, and the initial pressing load was set to 3N. The fixing blade 93 is made of urethane rubber having a rebound resilience of 50% (25 ° C.), a JIS-A hardness of 65 degrees, a thickness of 1.5 mm, a free length of 7 mm, and a width of 350 mm. The contact force was set to 15 N / m, and the contact angle was set to 70 °.

  The lubricant supply amount can be controlled by the rotation speed ratio θ between the photoconductor 10 and the application brush 91, and the lubricant supply amount increases as the rotation speed ratio θ increases. In Experimental Example 7, the supply amount of the lubricant was controlled by the rotation speed ratio θ between the photoconductor 10 and the application brush 91. Specifically, the application brush θ was reduced in accordance with the reduction in the shaving property of the photoreceptor 10, and the lubricant supply amount was reduced.

FIG. 21 is an example of a control parameter table showing the correspondence between the photoconductor wear speed and the application brush θ.
The photoreceptor abrasion speed was directly detected in the same manner as in Experimental Example 1, and was determined every 20 krot. Then, θ control of the application brush 91 was performed based on the control parameter table 37 shown in FIG.

  In Experimental Example 7, similar to Experimental Example 1, no problem occurred in both the quality of the cleaning blade wear and the difference in density variation from the initial image in the halftone even at the photoconductor travel distance of 300 krot.

  Here, a brief description will be given of the control of the lubricant supply amount conventionally performed in the lubricant application system. Since the thickness of the solid lubricant is reduced with the consumption of the lubricant due to durability (running of the photoreceptor), when the solid lubricant is pushed in by a spring load, the pressing force of the solid lubricant on the application brush is increased with the consumption of the solid lubricant. And the amount of lubricant applied decreases. Therefore, in the conventional lubricant supply amount control, in order to keep the lubricant application amount constant, the application brush θ is increased in accordance with the durability (the traveling distance of the photoconductor). On the other hand, in Experimental Example 7, in order to keep the amount of lubricant on the photoreceptor constant, the application brush θ is reduced in order to reduce the amount of lubricant applied in accordance with the variation in the abrasion of the photoreceptor 10. . Therefore, in the conventional lubricant supply amount control and the experimental example 7, the directionality of the lubricant application amount control using the application brush θ is different and conceptually completely different.

  In addition, the invention described in Patent Literature 1 is to increase the amount of a lubricant to be applied in accordance with the progress of the degree of wear of the cleaning blade in order to suppress a decrease in cleaning performance caused by wear of the cleaning blade due to durability. is there. Therefore, the invention described in Patent Document 1 is an experimental example in which the amount of the lubricant applied is reduced in order to keep the amount of the lubricant on the photoreceptor constant in accordance with the change in the sharpness of the photoreceptor due to the wear of the cleaning blade. No. 7 is different from the concept of controlling the amount of applied lubricant, and is conceptually completely different.

  As described above, Experimental Example 7 has a configuration in which θ of the application brush 91 of the lubricant application device 90 is reduced according to the reduction in the shaving property of the photoconductor 10. Thus, the amount of the lubricant supplied to the photoconductor 10 can be controlled, and the stability of the lubricant on the photoconductor can be ensured. Further, since the amount of the lubricant on the photosensitive member is stabilized, it is possible to prolong the service life of the cleaning blade 70 and to suppress the fluctuation of the image density, as in Experimental Example 1.

  The embodiment to which the invention made by the inventor is applied has been described above. However, the present invention is not limited by the description and the drawings that constitute a part of the disclosure of the invention according to the above-described embodiment, and various modifications can be made without departing from the gist of the invention described in the claims. It is.

  For example, although the case where the shaving property of the photoconductor 10 (an example of the first image carrier) fluctuates nonlinearly has been described, the present invention can be applied to the case where the shaving property of the photoconductor 10 is linear. is there.

  In the above-described embodiment, the example of the image forming apparatus including the intermediate transfer body 51 as the second image carrier has been described. However, the present invention is applicable to an image forming apparatus in which the intermediate transfer body 51 does not exist. is there. For example, the second image carrier may be a recording material such as a sheet on which an image is formed.

1, 1A: Image forming apparatus, 10: Photoconductor, 20: Charging device, 30: Exposure device, 31 to 37: Control parameter table, 40: Developing device, 41: Developing sleeve, 50: Transfer device, 51: Intermediate transfer Body: 60: Charge adjusting device, 70: Cleaning blade, 75: Cleaning auxiliary device, 76: Cleaning auxiliary brush, 77: Collection roller, 80: Abrasion amount measuring section, 90: Lubricant application device, 91: Application brush, 92 ... solid lubricant, 100 ... control device, 101 ... memory device, P ... inflection point

Claims (11)

A rotatable first image carrier for carrying a toner image;
A charging unit for charging the first image carrier;
An exposure unit for irradiating the first image carrier with light to write an electrostatic latent image;
A developing unit that develops the toner image from the electrostatic latent image written by the exposure unit on the first image carrier;
A transfer unit that transfers the toner image developed on the first image carrier to a second image carrier;
A cleaning member that contacts the first image carrier and collects transfer residual toner that is toner remaining on the first image carrier after transferring the toner image;
A cleaning auxiliary device provided between the transfer unit and the cleaning member, the cleaning auxiliary device including a cleaning auxiliary brush for collecting the transfer residual toner while rotating in contact with the first image carrier;
A wear amount measuring unit for measuring the wear amount of the surface of the first image carrier;
The first image of the supplied lubricant according to the non-linearly fluctuating abrasion of the first image carrier based on the abrasion amount of the first image carrier measured by the abrasion amount measurement unit. A controller for controlling the amount of lubricant on the first image carrier by adjusting the amount of lubricant collected from the carrier by the cleaning member and the cleaning assist device ;
The controller decreases the amount of the transfer residual toner collected by the cleaning auxiliary brush and increases the amount of the transfer residual toner reaching the cleaning member as the abrasion of the first image carrier decreases. image forming apparatus causes. Wherein, in response to the abrasion of the first image bearing member, an image forming apparatus according to claim 1 for controlling the rotational speed of the auxiliary cleaning brush. The cleaning auxiliary device further includes a rotatable collection roller for collecting the toner from the cleaning auxiliary brush,
Wherein, the first in accordance with the abrasion of the image bearing member, an image forming apparatus according to claim 1 for controlling the push-in amount of the collection roller with respect to the auxiliary cleaning brush. The cleaning auxiliary device further includes a rotatable collection roller for collecting the toner from the cleaning auxiliary brush,
Wherein, in response to the abrasion of the first image bearing member, an image forming apparatus according to claim 1 for controlling the rotation speed of the collecting roller. Wherein, in response to the abrasion of the first image bearing member, an image forming apparatus according to claim 1 for controlling the charge amount of the toner that reaches into the cleaning unit. A charge amount adjusting unit disposed on an upstream side in the rotation direction of the first image carrier with respect to the cleaning member, for adjusting a charge amount of the transfer residual toner on the first image carrier; ,
The image forming apparatus according to claim 5 , wherein the control unit controls an output of the charge amount adjustment unit in accordance with a sharpness of the first image carrier. The measurement period of the amount of wear of the first image carrier by the abrasion amount measurement unit is finely set in the initial stage of traveling of the image carrier, and the inflection of the wear characteristic with respect to the traveling distance of the first image carrier. The image forming apparatus according to claim 1, wherein the setting is made roughly after the point. The image forming apparatus according to claim 1, wherein the wear amount measuring unit directly measures the wear amount of the first image carrier by a spectroscopic method or an eddy current method. The wear amount measuring unit measures a surface potential of the first image carrier charged by the charging unit, and measures a measured value of a surface potential of the first image carrier and the first image carrier. The image forming apparatus according to claim 1, wherein the wear amount of the first image carrier is calculated from a table in which a relationship between the surface potential and the wear amount is registered. The wear amount measurement unit uses a table in which the relationship between the travel distance of the first image carrier and the wear amount of the first image carrier is registered for each of the average printing rates determined in advance. The image forming apparatus according to claim 1, wherein the wear amount of the first image carrier is calculated. A rotatable first image carrier for carrying a toner image, a charging unit for charging the first image carrier, and an exposure for irradiating the first image carrier with light to write an electrostatic latent image A developing unit that develops the toner image from the electrostatic latent image written on the first image carrier by the exposure unit; and a developing unit that develops the toner image on the first image carrier. A transfer unit that transfers the toner image to the second image carrier, and a cleaning unit that contacts the first image carrier and scrapes off the transfer residual toner that is the toner remaining on the first image carrier after transferring the toner image. A cleaning auxiliary device provided with a member, a cleaning auxiliary brush disposed between the transfer unit and the cleaning member and configured to collect the transfer residual toner while rotating in contact with the first image carrier; Carrier in image forming apparatus provided with image forming apparatus A lubricant amount control method,
The image forming apparatus is configured to control the amount of the supplied lubricant in accordance with the non-linearly fluctuating abrasion of the first image carrier based on the wear amount of the first image carrier measured by the wear amount measurement unit. A control unit that controls an amount of the lubricant on the first image carrier by adjusting an amount of the lubricant collected from the first image carrier by the cleaning member and the cleaning auxiliary device. ,
The controller decreases the amount of the transfer residual toner collected by the cleaning auxiliary brush and increases the amount of the transfer residual toner reaching the cleaning member as the abrasion of the first image carrier decreases. A method for controlling the amount of lubricant on the image carrier to be performed .

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